Mean dichotic digits scores  were only different in the left ear (p = 0.054). The comparison of pre and postacoustic reflex testing indicated mean differences (p = 0.032) between the exposed (4.58 ± 6.8) and controls (0 ± 4.62) groups. This study provides evidence of a possible temporary effect (hearing fatigue) at the level of the acoustic reflex of the stapedius muscle. The permanent effects were identified mainly at the level of the high brainstem and in the auditory ability of binaural integration.This study aimed to assess temporary and permanent auditory effects associated with occupational coexposure to low levels of noise and solvents. Cross-sectional study with 25 printing industry workers simultaneously exposed to low noise (<80 dBA TWA) and low levels of solvents. The control group consisted of 29 industry workers without the selected exposures. Participants answered a questionnaire and underwent auditory tests. Auditory fatigue was measured by comparing the acoustic reflex threshold before and after the workday. Workers coexposed to solvents and noise showed significantly worse results in auditory tests in comparison with the participants in the control group. Auditory brainstem response results showed differences in III–V interpeak intervals ( Workers in the printing industry are commonly exposed to solvents and noise . EpidemiAlthough pure tone audiometry is an important test for the annual monitoring of workers, it may not be sufficient to detect early signs of hearing loss in workers exposed to chemicals ,17,18,19Before occupational hearing loss occurs, early signs and symptoms can be identified, such as hearing fatigue, difficulty understanding in environments with competitive noise, and tinnitus . HearingAuthoritative documents which reviewed the evidence available to facilitate the proposal of guidance to the occupational health community have concluded that the effects of workplace chemicals on the auditory system can be diverse ,18,19. TThe preponderance of the evidence indicates that some chemicals affect not only the sensory organ of the auditory system (the cochlea), but also lead to adverse effects on the central auditory structures . ClinicaBecause of the ubiquity of their use in the workplace, solvents are one of the most studied class of chemicals for their toxicity. Millions of workers around the world are exposed to organic solvents such as toluene and xylene in several industrial sectors ,12,17. SThe Echoscan device  was desiThere is no consensus on clinical audiology protocols to identify early cases of solvent-induced hearing dysfunction and provide hearing care for those with normal audiometry who experience listening difficulties following combined noise and solvent exposure. Studies have suggested the use of a peripheral and central test battery to identify early cases of occupational hearing impairment ,27,28.Th present study sought to answer the three questions: Are low levels of noise and solvent coexposure harmful to hearing? If so, are these temporary or permanent effects? Which audiological tests are the most sensitive to detect the early signs of these effects? The aim of this study was to assess the temporary or permanent auditory effects associated with occupational coexposures to low levels of noise and solvents in printing facilities using an auditory test battery to identify early signs of hearing dysfunction.The present study used a cross-sectional design. It was approved by the Research Ethics Committee of the Universidade Tuiuti do Paraná under number 3.401.602 and CAEE: 10758719.5.0000.8040. All procedures complied with the ethical principles of Resolution 466/2012 of the National Health Council of Brazil. Data produced in this study were analyzed in accordance with a prespecified analysis plan detailed in the documentation for the University’s review board. Workers from two printing companies located in southern Brazil were selected to participate in the study. Both companies manufacture and assemble high-quality calendars, catalogs, packaging, folders, stationery products, files, and magazines . Both coData collection took place in two phases. Phase I was carried out on the companies’ facilities to measure auditory fatigue. Phase II was carried out at the audiology clinic of IELUSC University to diagnose permanent effects on hearing. The studied printing industries had similar physical facilities, production processes, and exposure scenarios, which were demonstrated by the document analysis performed in Phase I. This enabled us to combine the data for the analysis. The protocol and aims of the study were explained to representatives of the two companies. Agreement letters were signed, and participant selection followed.3) for ethylbenzene, 78 ppm (340 mg/m3) for xylenes, 78 ppm (290 mg/m3) for toluene, and 50 ppm (176.24 mg/m3) for n-hexane [The study groups were selected using a convenience sampling , with pan-hexane  for a 48n-hexane . The onlFifty-four workers participated in the study; twenty-five of them were exposed to low levels of noise and solvents  and twenty-nine were not exposed . Out of the 25 exposed workers, 10 participated in phase I, 8 in phase II, and 7 participated in both phases see . ParticiThe companies’ audiometric records were examined to identify those who presented average hearing thresholds  below 25 dB HL. Those who met that criterion were asked to answer a questionnaire that gathered information on previous occupational and nonoccupational exposure, hearing symptoms, family history of hearing loss, use of individual hearing protectors, general health, and drug use, among other health information. As a follow-up, workers underwent an inspection of the external auditory canal to check for any impediments to the performance of an audiological assessment , acoustic immittance testing, and the assessment of auditory fatigue (Phase 1). Data collection took place in a quiet room on the companies’ facilities, which included a portable audiometric booth. Hearing examinations were performed at least 14 h after the last exposure to noise to minimize the detection of temporary threshold shifts. On the same day, after an average of six hours after the beginning of their work shift Echoscan measurements were repeated to diagnose the auditory fatigue. With one exception, all participants from the exposed group reported using hearing protectors (earplugs with an approximate noise attenuation rating of 16 dB) throughout the work shift.Phase 2 consisted of completing the test battery at the Audiology Clinic School, with the following procedures: acoustic immittance, auditory brainstem response (ABR), and the dichotic digits test (DD), as described in The volunteers whose responses were not in the normal range on some tests were referred for hearing monitoring or consultation with a specialist. A documentary analysis of the chemical risk assessment conducted by the companies’ environmental risk prevention program was carried out. The reports described measurements conducted by an external contractor through individual sampling of representative subgroups of exposed workers in each of the participating companies. For the study participants who did not participate in the sampling, the mean value of the solvent concentrations evaluated for the same job and same work task was used to evaluate exposures. This analysis guided the selection of study participants from the printing, finishing, shipping, continuous improvement, and processing sectors. The results of the report indicated much lower time-weighted average exposure levels to solvents than the Brazilian exposure limits for each of the detected solvents. Passive samplers were also used to collect full-shift air samples in a subsample of each of the groups of workers who had the same overall exposure profile for the agent(s) under study. The sampling device was positioned as close as possible to the breathing zone of the worker (carried by the worker). The adsorption tube samples were sealed and mailed to the U.S. for gas chromatography. These measurements were carried out on the day of the hearing tests. levels were actually higher than 85 dB(A).The information on noise dose, according to each participant’s sector and function, was obtained from the companies’ 2018 risk assessment reports. Noise levels ranged from 57 dB(A) to 83 dB(A). These levels were confirmed by a walk-through survey by the investigator team using the NIOSH Sound Level Meter app. All workers were exposed to noise levels below the limits established by NR15 of ≤85 dB(A) . Despite® Version 9.4 . PROC MIXED was used for the linear models. PROC GENMOD was used for the logistic regression models.The results of the hearing tests as continuous variables were analyzed with linear models assuming normality. An arcsine transformation was used for the measurements from the dichotic digits test. Dichotomous outcomes were analyzed with a logistic regression using exact tests and confidence intervals. Linear and logistic models were performed to estimate and test the effects on the exposure group. In addition to the exposure group, the models included variables for study, age, sex, previous noise exposure, and previous chemical exposure. A second set of models was performed with two exposure variables, noise level and current chemical exposure, replacing the exposure group. The same covariates were included. Adjustments were made for age and gender within the models, not just matching between groups. The adjustments were made even if there was no statistical significance. All calculations were performed using SASInformation on previous occupational and nonoccupational exposure, hearing symptoms, family history of hearing loss, use of individual hearing protectors, general health, and drug use was not significantly different among groups. Despite not being different between groups, we kept these variables in the model when testing for correlations. Significant (or quasi-significant) correlations were only observed between PTA results of the exposed group and the reported use of hearing protectors. The solvent concentration assessment results obtained from the measurements taken on the day of the hearing tests were in accordance with the results described in the risk assessment reports obtained from the participating companies. The levels of ethylbenzene ranged from 3.6 ng to 61 ng, n-hexane from 4.0 ng to 850 ng, xylenes from 3.5 ng to 53 ng, and toluene from 4.4 ng to 77 ng. The results were well below both the Brazilian exposure limits  and the n = 15) had at least one auditory and/or extra-auditory complaint, out of which 36% (n = 9) had itching, 24% (n = 6) reported discomfort with intense sound, 16% (n = 4) complained of otalgia, 12% (n = 3) had a feeling of ear fullness, 12% (n = 3) had difficulty in understanding speech in a noisy environment, 12% (n = 3) had tinnitus, and 8% (n = 2) had vertigo. It is important to note that all participants had average thresholds < 25 dB HL.No significant differences were observed in the rates of hearing complaints between the groups. The overall rates among the 54 participants were as follows: 60% (p = 0.022) and 4000 Hz for the left ear .p = 0.0523), PTA left 2000 Hz , PTA left 3000 Hz , PTA left 4000 , and PTA left 6000 Hz . The results of the linear and logistic models created to estimate and test for the effect of the two exposure variables, noise level and current chemical exposure (replacing exposure group), indicated a significant difference was observed in the results at the frequency of 4000 Hz for the left ear and the frequency of 6000 Hz for the right ear. When we tested for correlations among the variables included in the model, hearing protector use in the exposed group was inversely related to some pure tone audiometry thresholds, PTA right 3000 Hz , when the exposure group was in the model. The results of the linear and logistic models developed with two exposure variables, noise level and current chemical exposure levels, showed a statistically significant difference for noise at the frequencies of 500 Hz (p = 0.024) and 1000 Hz (p = 0.043) for the ipsilateral stimulation of the right ear and at 500 Hz for the ipsilateral stimulation of the left ear (p = 0.049). A between-group comparison of the intensities needed to trigger the acoustic reflex (dB HL) obtained through immittance audiometry only detected a significantly lower level at the contralateral stimulation at the right ear at 2000 Hz for the exposed group (p = 0.031). The risk estimate adjusted for noise and chemical exposure as variables revealed a significant difference (p = 0.010) between the exposed versus nonexposed group.The assessment of auditory fatigue using the Echoscan equipment was calculated through the difference of acoustic reflex measurement before and after their work shift see . The meap = 0.054). In the estimation of risk in the adjusted models with noise level and chemical exposure as exposure variables, a trend was observed for the difference between groups (p = 0.064).p = 0.046) and in the left ear   .This study aimed to assess temporary and permanent auditory effects associated with occupational coexposure to low levels of solvents and noise, using an auditory test battery, and the results showed it can be harmful to hearing, causing temporary and permanent effects. The temporary effect was identified at the level of the acoustic reflex of the stapedius muscle, which may be an early sign of hearing impairment. The permanent effects were identified mainly at the level of the high brainstem and in the auditory ability of binaural integration. The results of the Echoscan, auditory brainstem response (ABR), and dichotic digit tests (DD) indicated that these were the most sensitive tests in the early identification of auditory effects, both temporary and permanent.The studied population was young , had short tenures at the studied companies (5–7 years), and the volunteers were predominantly female. Neither of these variables was associated with the studied outcomes. An association with age was not expected, as our control group was matched by age to the exposed group and the logistic regression model adjusted for that. Regarding gender, the findings of this study do not fully agree with prevailing evidence. Female workers have been considered less vulnerable to the effects of noise , or it hAlthough auditory symptoms such as itching (likely to be explained by the earplug use), discomfort caused by loud sounds, otalgia, sensation of ear fullness, difficulty in understanding speech in a noisy environment, tinnitus, and vertigo were reported, no significant differences were observed between groups. Many of these specific complaints related to hearing dysfunction can be considered as preclinical, occurring prior to test results that would make the dysfunction explicit ,20.Although the hearing threshold means were within normal levels and the exposed group was exposed to low levels of noise and solvents, significant differences were observed at 6000 Hz in the right ear and 4000 Hz in left ear in the group comparisons , with poA significant difference between groups (with worse results from the exposed group) was only observed for the acoustic reflex at 2000 Hz in the right ear, by contralateral stimulation. Roggia et al.  also obsIn the analysis of auditory fatigue, the group coexposed to noise and solvents presented a difference in response between post- and pre-exposure acoustic reflexes thresholds (4.58 dB ± 6.8), indicating possible auditory fatigue . The EchEarlier animal experiments have shown that when low concentrations of solvents were present, noise exposure had to reach levels above 80–85 dB for the detection of an increase in reflex thresholds ,51. ExpoIn the present study, workers coexposed to noise and solvents within regulatory exposure limits displayed auditory fatigue at the end of their workday, which did not occur in the control group. Venet et al.  used thep = 0.064) was observed in the analysis of the exposure effect. This finding is in agreement with those from Fuente et al. [In the dichotic digits test, worse results were observed in the exposure group , with a e et al. , Fuente e et al. , Fuente e et al. ,13, Lande et al. . Fuente e et al.  suggestee et al. .A significant difference was only observed in the result of the ABR interpeak interval of waves III-V for both ears . When asFuente et al.  studied Roggia et al.  and TunsIn our analysis a significant difference was observed between exposure groups for the III–V interpeak interval for both ears. These findings are more likely associated with exposure to chemicals, which have neurotoxic properties, than with noise exposure. The III–V interpeak interval is related to signals generated in the brainstem, demonstrating the conduction between the cochlear nuclei and the superior olive . Thus, tEvaluating temporary effects of occupational exposures to noise on hearing presents significant challenges . Noise eThe tests used in this study were sensitive to the early detection of temporary as well as permanent changes in the auditory system of printing workers coexposed to low noise and low concentrations of solvents. Some authors have emphasized that performing pure tone audiometry alone is not enough to monitor the negative effects on the auditory system in workers exposed to chemical agents ,8,18,27.A temporary impairment of hearing capacity after exposure to factors that injure the ears is defined as auditory fatigue. Temporary dysfunction was detected in the exposed group through the Echoscan. Regarding permanent effects, previous studies had suggested that the dichotic digits test ,12,52, tThese tests were developed for clinical use and can identify functional alterations in the auditory pathway of workers coexposed to low noise and low concentrations of solvents. The motivation for including the assessment of hearing fatigue in this study was to examine the occurrence of temporary changes in hearing, from exposure scenarios that are considered safe. We also aimed to evaluate this new tool that could enable early detection and the recognition of workers susceptible to the development of hearing disorders. The result of auditory fatigue identified using the Echoscan followed the same trend observed in the response of other auditory tests, that is, poorer results among workers exposed to low noise and low concentrations of solvents in comparison with the unexposed group. The present study detected signs of auditory dysfunction that did not seem to be apparent to the individual, as well as to professionals who do not run statistical analyses of group results. Given that exposure scenarios in both companies were considered safe, that workers were young, and had a relative short exposure duration, our findings represent a challenge to prevention programs. Auditory monitoring of these workers seems to be needed, as well as referrals for clinical examinations that assess the peripheral and central auditory pathways.Investigations which examined the effects of solvents over time indicated that hearing loss was observable two to three years earlier than was usually seen with noise exposure ,17,18,19Pure-tone audiometry only informs us of the lowest sound that can be perceived in a quiet environment. It only describes some characteristics of the problem but not its potential cause. Information on word recognition difficulties or other hearing problems obtained through a questionnaire can indicate the need for referral to an audiological evaluation when they are inconsistent with pure-tone audiometric results. Moreover, it is important to examine if other hearing testing can complement the pure-tone audiometric assessment conducted with workers. The assessment of auditory fatigue by the Echoscan is an objective and quick test, since it does not depend on the worker’s active response, and it can be performed in a quiet room without the need for a soundproof booth. Thus, it has the possibility of being applied in numerous places, such as in companies of different fields, clinics, and hospitals. The Echoscan could facilitate the recognition of the most susceptible groups of workers and the early identification of temporary hearing effects in workers with normal hearing. Ideally, one would be able to monitor exposures to hearing hazards throughout the day, to be able to understand possible causes of the fatigue. This is likely to be hard to implement, and this is not the only potential barrier. The Echoscan evaluation requires workers to be tested before and after their shift. Time away from work is a concern for employers. After-shift testing would most likely require workers staying beyond their workday and could prove difficult to achieve. In addition, many workers already have hearing losses, which would preclude them from being tested with the Echoscan. Even some workers with normal hearing thresholds can have an absence of evoked distortion-product otoacoustic emissions and acoustic reflexes. These need to be present for the completion of the test. An important limitation of this study is the lack of detailed current and previous exposure information of the participants, including data on the individual uptake of solvents. Given its cross-sectional design, we were not able to establish causation, but rather, association between outcome and studied variables. In addition, we used a convenience sample, as a random sample was not possible due to the limited access we had to study populations. Statistical inferences based on a convenience sample only pertain to the sample and not the population it was drawn from, which limits the generalizability of the results to other samples and populations.While our results indicated that workers in the printing industry have significantly higher rates of peripheral and central auditory dysfunctions than nonexposed persons, it was not possible to identify with precision the contribution that their exposures represented to their hearing status. Many factors can impair the auditory system, several of which were controlled for in this study . Studies with larger groups and better exposure information could help shed light on the contribution of different risk factors. In the investigation of temporary auditory effects, it would be ideal to conduct full shift noise and solvents exposure measurements on the day of the testing, identifying possible peaks of exposure, not only their time-weighted averages. Another important limitation of this study is that some participants, even with hearing thresholds within normal limits, did not present acoustic reflex responses or distortion-product otoacoustic emissions. Thus, it was not possible to include these participants in the study. Finally, the results of hearing fatigue were based on the standards of the equipment, and it would be informative to functionally verify hearing fatigue using an alternative test.Occupational coexposure to low noise and low concentrations of solvents can be harmful to hearing, causing temporary and permanent effects. This study provided evidence for a possible temporary effect, which may be an early sign of hearing dysfunction. The permanent effects were identified mainly at the level of the high brainstem and in the auditory ability of binaural integration. Workers exposed to low concentrations of solvents and noise had significantly poorer performance than nonexposed subjects in pure-tone audiometry, middle ear reflex, dichotic digits, auditory fatigue test, and auditory brainstem response. The results suggest the studied workers had both peripheral and central auditory dysfunctions that could be attributed to their exposures. These results can guide audiologists in the selection of tests to include in a battery for evaluating this population. Finally, the traditional approaches for assessing occupational hearing loss need to be re-examined to allow the early assessment of hearing functions in workers exposed to chemical agents.


TAS1R2 has been associated with dental caries at a high risk in permanent teeth among school children and adults. To date, little is known about the association of this SNP with sweet intake and caries risk in the primary school children.Dental caries is one of the most prevalent chronic diseases worldwide among children. The rs35874116 single nucleotide polymorphism (SNP) in the sweet receptor gene TAS1R2 was sequenced to analyse rs35874116 polymorphism. A questionnaire was used to collect information about socio-demographic information, frequency of sweet intake and oral hygiene habits. Multiple logistic regression models were applied to assess the relationship of rs35874116 polymorphism with frequency of sweet intake and S-ECC among the five-year-old children.Total of 236 children were included, namely 118 subjects in the non-caries (NC) group and severe early childhood caries (S-ECC) group, respectively. Oral mucosa cells were collected from all the selected children, and the full length of exon 3 in x2 = 5.436, p = 0.020), and S-ECC individuals were more likely to be TT genotype carriers than NC individuals . Multiple logistic regression analyses showed that the TT genotype of rs35874116 was not only significantly related to the frequency of sweet intake  but also significantly associated with S-ECC .Children with the TT genotype of rs35874116 had a higher frequency of sweet intake than CT/CC carriers (51.3% vs. 32.7%; The rs35874116 polymorphism might increase sweet intake and the risk of S-ECC among five-year-old children in Nanning, China. Dental caries is one of the most prevalent chronic diseases worldwide among children. It is reported that 70.9% of five-year-old Chinese children suffer from dental caries . It has Sweet preferences are shaped by a high number of environmental, cultural, and nutritional factors, including genetic. Genetic variation plays a crucial role in individual differences in sweet preferences, which ultimately influence selection of dietary intake and health . The relTAS1R2 is related to interindividual differences in sugar sensitivity. To demonstrate the relationship between the TAS1R2 gene and sweet intake as well as sugar-dependent caries disease, studies have focused on the relationship between rs35874116 polymorphism in the TAS1R2 gene with sweet consumption and dental caries over the past few years [Taste receptor family 1 members (T1Rs) lead to the perception of sweet and umami taste , 7. The ew years .The rs35874116 polymorphism was classified into three genotypes based on the mutational alleles: 1) homozygous polymorphic genotype TT, 2) homozygous wild-type CC, and 3) heterozygous type CT. The polymorphism rs35874116 is the substitution of an isoleucine for valine at position 191. TT indicates those that are homozygous valine/valine at position 191, and CT and CC indicates who are isoleucine carriers  at position 191. It was shown that people who are TT type carrier have greater sugar consumption . HoweverIn this study, we targeted rs35874116 polymorphism and explored the association of rs35874116 polymorphism with sweet intake and caries risk in five-year-old Chinese children. Our hypothesis was that rs35874116 polymorphism might be associated with the child’s frequency of sweet intake and severe childhood caries (S-ECC).A case-control group–design was applied in this study. The control group was the non-caries (NC) group, and the case group was S-ECC group. The criteria for the S-ECC group were those children with decayed, missing, and filled teeth (dmft) value equal to or more than six , and theC was 1.0. The value of α and β were set at 0.05 and 015, respectively. Zα = 1.282 and Zβ = 1.96. The values of π1 and π2 referred to the predicted mutation rates of rs35874116 in the control and case groups. The largest sample size was required when π1 = 0.8 and π2 = 0.6, respectively. Therefore, the calculated sample size should be 118 children for each group. All statistical tests were two-sided.The number of children was set to be equal in both groups. Thus, the value of The subjects were recruited from our previous study . In totaBefore the investigation, this study was approved by the Medical Ethics Committee of Guangxi Medical University (No.2015-2-12-1) and written informed consent for participation was obtained from the caregivers. All methods were performed in accordance with the Declaration of Helsinki.A questionnaire designed based on our previous study  was usedThe questionnaire was pilot tested among the caregivers of the 5-year-old children prior to the study. In the study, the questionnaires were distributed by the kindergartens to the caregivers, who completed the questionnaire at home and returned it to the kindergartens.Clinical examinations were performed in the classroom under natural light with the children lying on a desk and the examiner seated on a chair behind the subject. The examiner was trained and calibrated for dental caries diagnosis based on the World Health Organization (WHO) Health Survey Methods for field studies . Caries Fasting was requested 30 minutes before oral mucosa cell collection for all the children. A disposable oral mucosa swab was used to non-invasively scrape the buccal mucosa back and forth approximately 30 times to get enough oral mucosa cells, which required full contact with oral mucosa, taking care to not touch the degreased cotton part. The wiped swab was put into the collection tube, which was sealed and kept in a foam box with dry ice and then sent to the lab within 4 h. All the swabs were marked and stored at − 20 °C and sent for genotyping within a week.Tas-exon3-F1: 5′- GGTGGCTTGCACTAGGTG-3′;Tas-exon3-R1:5 ‘- GTGTCTGGAAGAATGGGATA-3’.Extraction of DNA from mucosal cells was carried out using a DNA Extraction Kit (Tsingke). DNA was successfully extracted and identified as purity by 1% agarose gel electrophoresis and stored at − 20 °C. Exon 3 is located at 4676 bp–5449 bp, with a length of 774 bp. A pair of primers was designed according to the corresponding intron to amplify the full length of exon 3 (product full length 990 bp):2O 17 μl. The reaction conditions were as follows: initial denaturation at 96 °C for 5 min; 35 cycles of denaturation at 96 °C for 30 s, primer annealing at 54 °C for 30 s, and extension at 72 °C for 1 min; and a final extension at 72 °C for 5 min. Amplification products were stored at 4 °C. A DNA gel magnetic beads recovery kit (Tsingke) was used to purify the target fragments. The purified target products were used for full-length bidirectional gene sequencing by the Guangzhou Tsingke Biotechnology Company . Variant Reporter software was used to analyse the sequencing results, and rs35874116 sequence was selected as a reference sequence. The rs35874116 polymorphism was classified into three genotypes .PCR amplification products were detected by 2% agarose gel electrophoresis. Reaction system (50 μl): 2 x TSINGKE Master Mix (blue) 25 μl, TAS-EXON3-F1 (10p) 2 μl, Tas-exon3-R1 (10p) 2 μl, genomic DNA template 4 μl, dd Hp value of less than 0.05 for all two-sided statistical tests was considered significant.SPSS 22.0 was used for statistical analysis. A chi-square test was used to compare the distributions of rs35874116 polymorphism (TT type vs. CT / CC type) between different groups of sweet intake frequency ((LS group and HS group) and between different groups caries statuses (NC group and S-ECC group). Multiple logistic regression analyses  were conducted to analyse potential relationship between rs35874116 polymorphism and the frequency of sweet intake or caries risk, controlling demographic and other potential confounding variables. A The distribution of social demographic factors between the LS and HS groups, and, between the NC and S-ECC groups are shown in Tables In total, 187 (79.2%) children were TT genotype carriers, 46 (19.5%) were CT genotype carriers, and the remaining three (1.3%) were CC carriers. In subsequent analysis, the CT and CC genotype carriers were combined into one group (CT/CC carrier), as in a previous study .x2 = 0.0863，p = 0.769). Children of the TT genotype carrier consumed a higher frequency of sweets than CT and CC carriers . There were more TT genotype carriers in the S-ECC group than in the NC group . Distribution of the rs35874116 SNP between different genders, frequencies of sweet intake and caries status Table The distribution of genotypes between sexes was not statistically significant (with sweet intake frequency in the full model by multiple logistic regression analysis was showed in Table The result of the relationship between rs35874116 polymorphism The result of the relationship between rs35874116 polymorphism with S-ECC in the full model by multiple logistic regression analysis was showed in Table The development of caries is affected by a combination of environmental and genetic factors, bacterial factors, dietary factors, fluoride exposure, oral hygiene, saliva composition and flow rate, and tooth structure . Sweet iTAS1R2 vary across ethnic groups, and the proportion of TT-type carriers was higher among Asian individuals than among Caucasian individuals. However, further investigation is required to establish the pattern of distribution of rs35874116 polymorphism in other ethnic groups. In addition, the distribution was not significantly different between sexes, which is similar to previous studies [In most studies, the frequency of the TT type was 38.5–60.7% among Caucasians –15. Howe studies , 13, indTAS1R2, which is related to both sweet consumption frequency and dental caries. One plausible explanation may be that the rs35874116 polymorphism resides in the predicted first large extracellular domain of the T1R2 receptor, which hypothetically contains the ligand-binding site for carbohydrates and dipeptide sweeteners, and consequently impacts sugar-dependent disease [The present study provides evidence for gene variation of rs35874116 within  disease . We foun disease . However disease , 14, in  disease  or more  disease , 16, whi disease , 16. The disease , 11, 17. disease . The resTAS1R2 and didn’t consider other SNPs which might be connected with sweet intake or caries. Second, sweet intake was measured with a single, dichotomized question, and our future work should include other measures of sweet preference and/or do more to measure actual consumption of carbohydrates. Finally, the subjects included only Chinese preschool children. Thus, as sweet intake changes with age, the potential relevance of the findings to an older Chinese population will require future study.The strength of the present study includes a relatively large sample size, which comprised 118 caries-free and 118 S-ECC children, whereas most other studies only examined a small group , 15, 17.TAS1R2 on sweet intake and caries risk in Chinese preschool children. However, these findings require further confirmation in older Chinese populations. Understanding sweet intake and dental caries at the molecular level has the potential to facilitate new, more targeted approaches to the prevention and treatment of caries.In conclusion, our study implies a possible influence rs35874116 polymorphism in


Despite of the heightened risks and burdens of physical comorbidities across the entire schizophrenia spectrum disorders (SSD), relatively little is known about physical multimorbidity (CPM) in this population. The study’s main objective was to explore the differences in the CPM prevalence between SSD patients and the general population (GEP).The primary outcome was to explore the difference in CPM prevalence in the younger SSD and GEP groups (<35 years).The secondary outcome was the number of psychiatric readmissions.This nested cross-sectional study enrolled 343 SSD patients and 620 GEP participants.Younger SSD patients had more than three-fold higher odds for CPM than GEP. We also demonstrated an association between the presence of CPM and the number of psychiatric admissions in the SSD population independently of possible confounders. We did not observe significant interaction of CPM and age in the prediction of clozapine use. Younger women with SSD had statistically significant, almost four-fold higher odds of CPM than women from GEP.This study suggests that women with SSD are at increased physical comorbidity risk compared to men, particularly early in the course of psychiatric illness. Our results highlight the importance of addressing physical health from the first contact with a mental health service to preserve general health, and provide the best possible treatment outcome. Treatment of SSD must be customized to meet the needs of patients with different physical multimorbidity patterns.No significant relationships.


We report a case of spine infection with mucormycosis that manifested signs of paraplegia in a patient suffering from disseminated mucormycosis. Timely and effective surgery was performed. A review of the literature is included.A patient with diabetic ketoacidosis complained of back pain and fatigue for one month, and his right lower extremity activity had been limited for 10 days. T4–T6 vertebral and paravertebral soft tissue-involved infections were identified by MRI, which were derived from right lung pneumonia. He underwent abscess debridement, spinal canal decompression, pedicle screw fixation and amphotericin B liposome injection. Histopathological examination revealed broad aseptate hyphae suggestive of invasive mucormycosis. There was improvement in neurological function after surgical and medical treatment. Three months after the surgery, the patient died of uncontrollable massive bleeding of the urinary system. Mucormycosis is characterized by rapid development and a high mortality rate. This case shows the significance of a multidisciplinary team in the diagnosis and treatment of patients with mucormycosis. In addition, orthopedic surgeons should design appropriate surgery plans for spine-involved mucormycosis patients.This case present a patient with paraplegia caused by the spread of pulmonary mucormycosis to the vertebral and paravertebral soft tissue of levels T4–T6. After medical treatment, surgical debridement and internal fixation, the patient recovered well but later patient died of possible disease dissemination to the renal or urinary tract which resulted in massive haemorrhage. Rhizopus, Lichtheimia, Mucor and Cunninghamella [Mucormycosis, previously known as zygomycosis or phycomycosis, is a rare and opportunistic fungal infection characterized by rapid development and a high mortality rate . The caughamella , 3. Mucoghamella . The porghamella .According to the region of infection, mucormycosis is divided into six types: rhinocerebral (most common), pulmonary, cutaneous, gastrointestinal, disseminated and other rare forms, such as osteomyelitis, peritonitis, endocarditis and renal infection . Spinal 9/L , and NEU = 83.84% . After application of moxifloxacin, rehydration, insulin and the correction of his ketosis and electrolyte disorder for 2 days, his body temperature was 38.5 °C. Cefoperazone  was given for 10 days, during which his body temperature was between 36.4 and 37.6 °C, PCT was 0.104 ng/mL, HR-CRP was 57.03 mg/L, WBC was 7.38 × 109/L , and NEU was 83.21%. The second CT examination , albumin was 36.6 g/L , serum potassium was 3.43 mmol/L L , ferritin was normal, and procalcitonin was 0.062 ng/mL. Microbiological and pathological examinations of the bronchoalveolar lavage fluid were negative. His blood glucose was13.8 mmol/L.A 48-year-old Asian male who had a history of diabetes was diagnosed with diabetic ketoacidosis and admitted to another hospital. He complained of upper back pain seven days before admission, accompanied by fatigue, nausea and a dripping feeling when urinating for four days. The blood glucose was 19.8 mmol/L , and the pH was 6.823 (7.35–7.45). The body temperature was 36 °C. Patient presented with altered mental status. The first chest CT  was given empirically, and posterior thoracic abscess debridement, spinal canal decompression and pedicle screw fixation were performed the next day . Disorders of these cells are key factors in vascular invasion . Our patMost mucormycosis spondylitis cases are not treated with surgery. Buruma et al.  reportedOnly 3 patients received surgical debridement of infected vertebral and paravertebral soft tissue. Chen et al.  reportedMucormycosis spondylitis and paraspinal abscess have different clinical manifestations. As described in Table, the general symptoms of mucormycosis spondylitis include malaise, weight loss, fever, local symptoms of pain (most common), nerve damage , paralysis, etc. . It is dTherapeutic measures to treat mucormycosis include early diagnosis, systemic antifungal therapy, basic disease control and aggressive surgical debridement . To dateInternal fixation has a positive effect on maintaining spinal stability and facilitating the clearing of infections in spinal infectious diseases . To our Spinal or paraspinal tissue-involved mucormycosis is seldom seen in the clinic and has a high mortality rate. Doctors must remain alert and aware of scarce spinal infectious diseases and do comprehensive clinical evaluations and pathological biopsies to diagnose them early. Multidisciplinary team diagnosis and treatment is particularly valuable for such diseases. It mainly involves surgery, internal medicine to adjust blood glucose, infection department to anti-infection treatment. Orthopedic surgeons should design appropriate and individualized surgery plans for spine-involved mucormycosis patients.


Vertigo is a debilitating disease affecting 15–20% of adults worldwide. Vestibular peripheral vertigo is the most common cause of vertigo, often due to Meniere's disease and benign paroxysmal positional vertigo. Although some vertigo symptoms can be controlled by conservative treatment and/or vestibular rehabilitation therapy, these treatments do not work for some patients. Semicircular canal occlusion surgery has proven to be very effective for these patients with intractable vertigo. However, its application is limited due to concern that the procedure will disrupt normal hearing. In this study, we investigated if occlusion of two semicircular canals would jeopardize auditory function by comparing auditory function and hair cell morphology between the surgical and contralateral ears before and after the surgery in a mouse model. By measuring the auditory brainstem response and distortion product otoacoustic emission 4 weeks post-surgery, we show that auditory function does not significantly change between the surgical and contralateral ears. In addition, confocal imaging has shown no hair cell loss in the cochlear and vestibular sensory epithelia, and scanning electron microscopy also indicates normal stereocilia morphology in the surgical ear. More importantly, the endocochlear potential measured from the surgical ear is not significantly different than that seen in the contralateral ear. Our study suggests that occlusion of two semicircular canals does not disrupt normal hearing in the mouse model, providing a basis to extend the procedure to patients, even those with normal hearing, benefitting more patients with intractable vertigo attacks. Vertigo has a high incidence rate worldwide, affecting between 15 and 20% of adults each year. Its prevalence rises with age, especially in adults over the age of 60. Long-term vertigo causes mood changes and leads to other serious consequences, such as falls, varying degrees of disability, and accidental deaths  is considered to be an effective treatment of vertigo in patients who are not responsive to conservative treatments. SCO is a surgical operation in which the endolymphatic flow is blocked by bone wax, bone shavings, fascia, biological glue or a laser after drilling in the bony wall of the semicircular canal , 8. At pThe goal of our study is to investigate if SCO would disrupt the auditory function. We examined auditory function, hair cell morphology, and endocochlear potential (EP) in a mouse model to determine if normal hearing is still retained after a surgical procedure that blocks the two semicircular canals . If the SCO surgery is observed to have a minimal impact on the auditory function of animal models, our experiments will provide a stronger basis for extending the treatment to patients with normal hearing, benefitting a wider range of patients suffering from intractable vertigo attacks.C57BL/6 mice with both sexes at 4 weeks of age were used for experiments. The care and usage of mice were approved by the Animal Ethics Review Committee of Beijing Capital Medical University.Animals were anesthetized through an intraperitoneal injection of ketamine HCl (120 mg/kg) and xylazine HCl (7 mg/kg). After anesthesia administration, the animal was placed on a preheated pad with a preset temperature of 37°C. The canalostomy procedure, including locating and exposing the posterior semicircular canal (PSC) and lateral semicircular canal (LSC) in neonatal and adult mice, has been previously described in detail . The surABRs were used to determine hearing threshold. ABRs were recorded using a Tucker-Davis Technologies workstation with SigGen32 software  in a sound-isolated chamber as previously described . Mice we1 and f2, with f2/f1 = 1.2 and the f2 level 10 dB lower than the f1 level) were delivered to the ear canal from the speakers through a coupler. The sound pressure obtained from the microphone in the ear-canal was amplified and computed from averaged waveforms of ear-canal sound pressure using the Fast-Fourier transforms. The DPOAE component at the frequency of 2f1-f2 was measured in response to the two-tone bursts. The DPOAE threshold is defined as the f1 sound pressure level (measured in decibels) required to produce a repeatable response above the noise level at the frequency of 2f1-f2 (Two EC1 electrostatic speakers (Tucker-Davis Technologies) were used for the measurement of DPOAE threshold. Two tone bursts with different frequencies  was used for imaging analysis.After measuring auditory function, mice were euthanized through CO2 inhalation, and then decapitated to remove the temporal bones. Under a dissecting microscope, a hole was poked at the apex of the cochlea. The round and oval windows were opened with a needle. The temporal bones were fixed in 4% paraformaldehyde in PBS for 2h. After rinsing three times with PBS, the inner ear, containing both the cochlea and vestibular end organs , was decalcified in 10% EDTA solution for 1.5 h. The bony wall was then removed and the organ of Corti and vestibular end organs were all dissected out. The auditory and vestibular sensory epithelia were treated with 0.3% Triton X-100  and 5% normal goat serum  in PBS for 2h at room temperature. The samples were then incubated at 4°C over-night with the anti-MYO7A antibody . After rinsing in PBS, the samples were incubated with secondary antibody tagged with Alexa Fluor 488  for 2h at room temperature. Alexa Fluor 594-conjugated phalloidin  was used for labeling F-actin. After rinsing with PBS, samples were mounted on glass slides with Fluoromount-G  and examined using a Leica scanning confocal microscope . ImageJ  were captured, and IHCs and OHCs were counted separately from confocal images off-line, as described previously . For couThe temporal bone tissues were placed in cold 4% paraformaldehyde solution for 24 h, and then in 10% EDTA solution for 3 days. After dehydration in graded concentrations of ethanol, the sample was embedded in graded concentrations of celloidin. Serial sections of the temporal bones were individually cut along the long axis of the two semicircular canals (PSC and LSC) at a thickness of 20 μm. The sections were transferred from an 80% ethanol storage solution and then stained with H and E.2. The cochlear wall was removed upon decalcification in 10% EDTA solution for 24 h. The cochleae were then post-fixed for 1 h with 1% OsO4 in 0.1 M sodium cacodylate buffer and washed. The cochleae were dehydrated via an ethanol series, critical point dried from CO2 and sputter-coated with gold. The morphology of the HCs was examined in a FEI Quanta 200 scanning electron microscope  and photographed.The cochleae from the surgical ear were fixed for 24 h in a solution of 2.5% glutaraldehyde and 0.1 M sodium cacodylate buffer (pH 7.4) containing 2 mM CaClt-test was used to determine statistical significance between two conditions  in hair cell counts or EP change. Two-way ANOVA with multiple t-tests using the Holm–Sidak correction for multiple comparisons was also used to determine statistical significance. P ≤ 0.05 was regarded as significant.Data are expressed as means ± standard errors. Student's Due to the inaccessibility to the superior semicircular canal during surgery in mice, LSC and PSC were chosen to be blocked in our study . Tone-evTo determine if the surgery successfully blocked the LSC and PSC, we examined LSC and PSC morphology in celloidin-embedded serial sections. For comparison, morphology of the control ear was also examined. n = 3, P > 0.05). We also used scanning electron microscopy to examine stereocilia morphology of hair cells in the surgical ear. Confocal microscopy was used to examine hair cell status in the cochlea 4 weeks after surgery. Vestibular hair cell morphology was examined in the surgical ear to determine if blockage of the lateral and posterior canals causes degeneration of hair cells in utricle, saccule and crista. Confocal microscopy was used to examine hair cell morphology. P > 0.05 for ABR and DPOAE, n = 6). P > 0.05 for ABR and DPOAE, respectively, n = 6). We also compared ABR and DPOAE thresholds between the surgical and contralateral ears after surgery, in order to minimize the possible effect of age-related hearing loss on our measurement. As shown in p > 0.05 for ABR and DPOAE, respectively, n = 6).To determine if SCO leads to hearing loss, we measured ABR and DPOAE thresholds. p = 0.71, n = 6) was found between the two ears after the surgery.The endolymph within the scala media exhibits a constant ~80-mV positive polarization with respect to the perilymph . This poIt has been known for a long time that surgically obstructing posterior semicircular canal is an effect way to treat benign positional vertigo , 13, 23.In the present study we show that ABR and DPOAE thresholds measured from the ear with occlusion of lateral and posterior semicircular canals were not significantly elevated when compared to the pre-operative thresholds and thresholds of the contralateral ear. Although previous studies also examined auditory function after SCO, our study differs from previous studies. First, we examined auditory function after two canals (PSC and LSC) were plugged. In most previous studies, only one canal, often PSC, was plugged. Second, we measured EP to determine if occlusion of two canals would affect EP. Although one study also measured EP after three canals were blocked in a guinea pig model, the EP was only monitored for a short period of time right after the surgery . No longTransient loss of hearing and vestibular function has been seen in patients and animal models after SCO procedures , 10, 32.There are two limitations to our study. The first limitation is that our conclusion that SCO exhibited no obvious effect on auditory function was only based on observations made in a period of 4 weeks after the surgery. Therefore, it is unclear if the procedure would have any negative impact on long-term auditory function. As obstruction of the canals is certain to lead to change in endolymph flow, it is yet to be determined if such change could eventually lead to endolymphatic hydrops . The secIn summary, our results revealed that the plugging two semicircular canals does not lead to detectable hearing loss. Hair cell morphology in the cochlea and vestibule appears to be normal with no signs of hair cell degeneration and loss. EP also shows no significant change despite change in the endolymph fluid movement in the canal. The fact that normal hearing is preserved in the mouse model with obstruction of two canals suggest that SCO procedure does not disrupt auditory function. The procedure can be extended to human patients with normal hearing to treat benign positional vertigo after vestibular function and balance of the patient are also considered in decision making about SCO surgery.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The animal study was reviewed and approved by Animal Care Committee of Beijing Tongren Hospital.TW performed the experiments, analyzed the data, and wrote the manuscript. HL and DH performed some experiments. YL and DH designed the experiments, analyzed the data, and revised and finalized the manuscript. All authors contributed to the article and approved the submitted version.This work was supported by National Natural Science Foundation of China grants #81870718 and #81770996 to YL.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Cognition was measured using the Repeatable Battery for the Assessment of Neuropsychological Status for Hearing impaired individuals (RBANS-H); subjective benefit was measured using the Nijmegen Cochlear Implant Questionnaire (NCIQ); the Glasgow Benefit Inventory (GBI); the Hearing Implant Sound Quality Index (HISQUIp = 0.038) and in the ≥ 60y group (p < 0.001); speech perception and subjective outcomes also improved; RBANS-H total score positively correlated with “Self-esteem” domain in NCp = 0.026).Prior to surgery: the RBANS-H total score positively correlated with the domains “Advanced sound”, “Self-esteem”, and “Social functioning” of NCIQ, and negatively with HADS scores. 12 months post-implantation: the RBANS-H total score increased in the < 60y (After implantation, both age groups demonstrated improved cognition, speech perception and quality of life. Their depression scores decreased. Age was inversely associated with cognition. Hearing loss is one of the leading contributors to years lived with a disability: over 5% of the world’s population–or 466 million people–have a disabling hearing loss. This number will increase as the population ages .Besides, about 47 million people were living with dementia in 2015, and this number is expected to triple by 2050 . Taking It was first stated in 1989 that hearing loss in elderly was strongly related to the risk of developing dementia . Several. It was established that hearing loss accounted for 8% of dementia cases occurring during midlife.A recent report by the Lancet Commission on “dementia prevention, intervention and care” emphasizes strongly on prevention . The aut1A.Cognitive load hypothesis: The high cognitive load of speech processing in people with hearing loss may accelerate neurodegeneration and brain atrophy. If cognitive resources are redirected to sensory processing, the resources available for cognitive processing are decreased, leading to cognitive decline.B.Common cause hypothesis: Both hearing loss and cognitive decline may result from a common genetic or environmental cause.C.Cascade hypothesis: Processing capacities may be lost when they are no longer used. Social isolation, depression, loneliness, reduced physical activity, and diminished quality of life may increase the vulnerability of people with a hearing loss and accelerate cognitive decline.D.Overdiagnosis or harbinger hypothesis: Hearing loss might be misdiagnosed as cognitive decline because some cognitive tests rely on verbal abilities . On the other hand, hearing loss might be an early symptom of cognitive decline.There are various hypotheses linking deafness with cognitive decline and dementia. Despite being addressed individually, these hypotheses cannot be independent; it is assumed that several mechanisms, or all of them, may act in combination .A.CognitThe last hypothesis leads to the assumption that correcting hearing loss with hearing aids or cochlear implants (CIs) could delay or even stop cognitive decline. Unfortunately, the results of the studies that measured the effect of hearing aids on cognition are inconclusive . There aThe tests used to evaluate cognition are diverse and usually designed for people with normal hearing. The Repeatable Battery for the Assessment of Neuropsychological Status was first adapted for people with a hearing loss (RBANS-H) in 2016 . In the To measure the change in cognition after implantation in two groups of CI users (< 60 y and ≥ 60 y) using the RBANS-H.To measure speech perception and subjective benefit of CI use  in the same groups.To assess the relationship between cognition and demographic data, audiometric outcomes, and subjective benefit.Based on these premises, the objectives of this study were:A prospective study of consecutive CI candidates was conducted in the Departments of Otorhinolaryngology at La Paz University Hospital and Ramón y Cajal University Hospital, Madrid, Spain. The study procedures were approved by the Ethics Committees .Participants were enrolled in the study if they met the following inclusion criteria: (1) they were post-lingually deaf adults scheduled for their first cochlear implantation, (2) they had no neurological disease or cognitive impairment, and (3) they were willing to undergo an evaluation for approx. 1–1.5 h. Written informed consent was obtained from all of them. The procedure involved cognitive evaluation, audiological evaluation, and a series of questionnaires about the perceived benefit of CI use and quality of life. All evaluations except one were conducted twice: just before implantation and 12 months after first CI fitting. All participants were implanted with a MED-EL device (Concerto Mi1000 or Syncrony 1210) .Patients were divided into two age groups: < 60 years and ≥ 60 years. This cut-off was previously established in other studies that evaluated age-related hearing loss , 16.Cognitive abilities were measured using the Repeatable Battery for the Assessment of Neuropsychological Status for Hearing impaired individuals (RBANS-H) . The meaThe total raw scores of the subtests were used to calculate the index score of each domain. These index scores were calculated using age-corrected tables with the following age categories: 12–13, 14–15, 16–19, 20–39, 40–49, 50–59, 60–69, 70–79, and 80–89 years. The final RBANS-H total score was calculated by the sum of these five index scores. This single total score was converted through a table to an age-corrected standard score with a mean of 100 and a standard deviation (SD) of 15 . If a participant had better hearing in the non-implanted ear, this ear was masked during testing.Audiological assessment was performed in a double-walled, soundproof booth using a two-channel Madsen AsteraPure-tone thresholds at 500, 1000, 2000, and 4000 Hz (PTA4) and the maximum Speech Discrimination Score (SDS) were measured before implantation under unaided conditions. After implantation, warble-tone thresholds in free field at 500, 1000, 2000, and 4000 Hz were measured using the CI. Speech perception was assessed with monosyllables, disyllables, and sentences in free field in quiet and noise. Participants were seated 1 m away from the loudspeakers at 0º azimuth. The tests were done without lip reading, at 65 dB SPL, and with a signal-to-noise ratio of 10 dB SPL speech-noise below the signal. The disyllable words are phonetically balanced words from the everyday vocabulary. The test was developed by Cárdenas de and Marrero . The mon19); Speech, Spatial and Qualities of Hearing Scale (SSQ12); and the Hospital Anxiety and Depression Scale (HADS). Except GBI that was only completed after implantation, all questionnaires were completed twice: before implantation and 1 year after first fitting.Subjective benefit of CI use was assessed using the Spanish versions of the following questionnaires: the Nijmegen Cochlear Implant Questionnaire (NCIQ); the Glasgow Benefit Inventory (GBI); the Hearing Implant Sound Quality Index  is the average of the individual item scores.The SSQalidated  12-item The HADS is a validated tool for measuring depression and anxiety . It cons19, SSQ12, HADS) between the age groups (< 60y and ≥ 60y) at two time points (before and after implantation), the t-test  or the Mann–Whitney U test were used. To measure the difference within the groups, the t-test  or the Wilcoxon test were used. Normality was assessed by the Kolmogorov–Smirnov test and Q-Q plots.To compare cognition (RBANS-H), audiometric data and self-reported outcomes . Analysis of variance (ANOVA) was used to measure the association between gender and cognition.Pearson’s correlation coefficient was independently calculated for the < 60y and the ≥ 60y group to evaluate the relationship between cognition (RBANS-H), age, audiometric data (PTA4 and speech perception test results), and the questionnaire scores  was considered significant. Statistical analyses were done in the SPSS software package v24.0 .Missing data and the response option “Not applicable” were treated as missing values. A level of Demographic characteristics and outcome measures are presented as absolute values, percentages and, where appropriate, the mean and ± SD are provided.n = 28, mean age = 48.7 ± 8.3 years) and ≥ 60 years . The demographic data of both groups are presented in Table 63 participants were enrolled in the study: < 60 years . No difference between the groups was found in the total RBANS-H or domain scores post-implantation (t-test) . In the ≥ 60y group, the Wilcoxon signed rank test revealed a significant increase in the “Visuospatial/constructional” (p = 0.036), “Language” (p = 0.005), and “Delayed memory” scores (p = 0.002).Pre-implantation, the total RBANS-H score and the “Visuospatial/constructional” domain score were significantly higher in the < 60y group than in the ≥ 60y group  .In both age groups, all NCIQ subdomain scores increased significantly after 12 months of CI use Fig. A and B. On average, the overall GBI score and the general subscale score were highly positive above 30) in both age groups  . An improvement in perceived hearing disability was reported by 89% of participants in the < 60y group and by 87% in the ≥ 60y group.The pre-implantation SSQ.3) Fig. B. After Before implantation, the mean anxiety scores indicated a “borderline abnormal” anxiety level in both groups  Fig. C. After After 1 year of CI use, the mean depression scores decreased significantly in both age groups: from 5.8 ± 4.3 to 4.4 ± 4.2 in the < 60y group and from 7.3 ± 5.3 to 6.3 ± 4.4 in the ≥ 60y group . Men in the ≥ 60y group had higher scores than women in the “Visuospatial/constructional” domain  and in the “Attention” domain .Pre-implantation, men in the < 60y group had higher scores than women in the “Attention” domain . Post-implantation, the age in the same group negatively correlated with the total RBANS-H score (p = 0.023), the “Visuospatial/constructional” (p = 0.010), “Attention” (p = 0.041), and “Delayed Memory” (p = 0.019) domain scores. In this group, age had a significant negative correlation with the improvement in the total RBANS-H score (p = 0.026).Pre-implantation, the age in the ≥ 60y group had a significant negative correlation with the “Delayed Memory” domain (p = 0.032). Post-implantation, the “Visuospatial/constructional” domain score correlated with the monosyllable test in silence (p = 0.029) and noise (p = 0.033), the disyllable test in silence (p = 0.007), and the sentence test in noise (p = 0.021).Some positive correlations between cognition and the audiometric outcomes were found in the ≥ 60y group. Pre-implantation, the “Immediate memory” domain score correlated with the outcomes of the sentence test in noise .19, SSQ12, and HADS questionnaires. These subjective outcomes along with gender, and age were associated with the RBANS-H cognition scores.We also demonstrated an improvement in speech perception, besides perceived sound quality, and quality of life using the NCIQ, GBI, HISQUIIn recent years, there has been a growing interest in the evaluation of cognitive abilities. The most widely used tools to measure cognition in research and clinical trials are the Mini-Mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA), the Mini-Cog test, the Addenbrooke's Cognitive Examination-Revised (ACE-R) , and theThe first objective of our study was to measure the changes in cognitive performance 1 year after CI surgery in two age groups of people with severe-to-profound hearing loss. Some authors have previously used the RBANS-H to measure cognitive performance in people with hearing loss: age ≥ 55y , age ranIn the present study, both “Memory” domains (“Immediate memory” and “Delayed memory”) significantly improved in the < 60y group, while the “Delayed memory”, “Visuospatial/ constructional” and “Language” domains improved in the ≥ 60y group. Our results are similar to those reported by Claes et al. , and Mer19, SSQ12, and HADS questionnaires.The second objective of our study was to measure the changes in speech perception and assess the subjective benefit of CI use in two age groups 1 year post-implantation. We demonstrated that cochlear implantation led to better speech perception and increased quality of life as measured by the NCIQ, GBI, HISQUIAccording to previous research, cochlear implantation leads to better speech discrimination in a wide range of ages. Unlike Völter et al. , who fou19, and SSQ12 questionnaires in both age groups after implantation. This perceived increase in quality of life has been demonstrated by our team [Although hearing restoration is the main aim of cochlear implantation, CI use has a wider impact on the user’s quality of life. In this study, higher scores were found in the NCIQ, GBI, HISQUIour team , and by our team  in peoplMore specifically, Völter et al.  found thPeople with hearing loss are more likely to have multiple psychological challenges such as anxiety and social isolation. In addition, hearing loss increases the risk of depression . The preThe third objective of this study was to analyse the relationship between cognition and the demographic variables , the audiological outcomes, and the subjective benefit of CI use.In this study, men had better cognition scores than women in some RBANS-H domains before implantation.Gender has been associated with cognitive abilities. There is some evidence that women might be more likely than men to develop dementia . Sarant Cognitive declines and the associated neuropathological changes are clearly age-related . In our We found an association between audiological outcomes and two cognitive domains in the ≥ 60y group. In this age group, better results in the sentence test in noise corresponded to better scores in the “Immediate memory” domain pre-implantation. Post-implantation, several speech tests correlated with the “Visuospatial/constructional” domain scores.Some authors have tried to determine whether better cognitive abilities could predict better post-implantation hearing outcomes, since cognitive skills are thought to contribute to speech performance. This is even more important in challenging hearing conditions like listening with a CI, as there are less spectrum-temporal issues. However, to date the results have been inconclusive , 32, 42.Recently, Vasil et al.  reportedWe found several interesting interactions between cognition and the subjective benefit of CI use, mainly in the ≥ 60y group.In the ≥ 60y group, the total RBANS-H score correlated with the “Advanced sound”, “Self-esteem”, and “Social” NCIQ domains pre-implantation, and with the “Self-esteem” domain post-implantation. In the study by Völter et al. , advanceSocial isolation may lead to anxiety and depression as well as to a decrease in cognitive abilities in CI candidates, and mental health problems could be the link between hearing loss and cognition. Therefore, depression might add cognitive problems in people with hearing loss . This coA potential limitation of this study might be the learning effect on the RBANS-H scores, because the same version was used pre- and post-implantation. Individuals might have improved their cognition scores because they had already done the same exercises before. This limitation may be addressed using two different RBANS-H versions, although Claes et al.  stated tDespite that all patients had bilateral hearing impairment and similar duration of deafness, the precise benefit obtained from the use of one or two hearing aids prior to cochlear implantation could have been somehow different between both age groups. Although unlikely, this difference could have impacted the different baseline cognitive status.Due to the nature of cognitive decline, it should be monitored over a long period of time. So, a longer follow-up interval after implantation would potentially be more informative, because the effects of CI use are not always observed in studies with short follow-up periods.Future studies would benefit from taking other modifiable risk factors of cognitive decline defined by Livingston et al.   12 months after cochlear implantation.Speech perception and quality of life improved after cochlear implantation, the results being similar in both age groups. Depression scores significantly decreased in both age groups.Age was strongly associated with the post-implantation cognitive outcomes. In the ≥ 60y subjects, the improvement in quality of life was positively correlated with cognition.Further long-term studies are imperative to understand the long-term effects of cochlear implantation and other possible variables on cognition.


With the universal hearing screening we can prevent auditory disorders in children.To characterize the program of neonatal auditory screening into a population of neonates.longitudinal cohort study. We surveyed the clinic's database on neonatal auditory screening in the city of Porto Velho, Rondônia.Among the 6,889 newborns in the database, 5,700 (82.7%) passed and 1,189 (17.3%) failed the first screening. Of the group which failed 900 (75.7 %) returned for retesting. Among these, 15 (0.22 %) newborns had hearing loss confirmed. The most prevalent was neural hearing loss with 46.7% confirmed cases; they had hyperbilirubinemia as the most prevalent risk factor.hyperbilirubinemia was the most prevalent risk factor found in the group of hearing impaired children. The prevalence of hearing loss was of 2 in 1,000 newborns. It is important to highlight the relevant association between neural hearing loss caused by hyperbilirubinemia and sensorineural hearing loss of unknown causes. Hearing may be the main means of contact men has with the environment, at least as far as basic interaction goes, which allows for the development of language and the intellect. For this reason, nature provided men with a noteworthy system to capture, amplify, perceive, discriminate and interpret sounds. It is in this order that the entire sound energy processing happens from the time it gets to the ear pinna, until it reaches the cerebral cortexOne of the main disorders which may impact language and speech development is hearing impairment. The American Speech-Language-Hearing Association considers that hearing impairment represents 60% of communication disordersHearing impairment can be classified as to the time when it occurs. Whether the hearing loss happens before or during birth - called congenital hearing loss; and when it happens after birth it is called acquired hearing lossAccording to the Brazilian Committee of Hearing Loss in Children5, the incidence of significant bilateral hearing loss in healthy neonates is estimated to be between one and three neonates for every 1,000 births and in about 2 to 4 for every 1,000 babies coming from the Intensive Care Unit (ICU).In 1994, the Joint Committee on Infant Hearing (JCIH)6 established the goal of universal detection of hearing loss in children through Universal Neonatal Hearing Screening (UNHS), and the development of studies to detect them, so as to make early intervention possible.In 1998 the Universal Neonatal Hearing Screening Support Group (UNHSSG) was created, under the coordination of audiologist Mônica Jubran Chapchap, with the goal of making UNHS operational in Brazil. Since then, negotiations are under way in order to create a committee to draw UNHS resolutionsThe first resolution of the Brazilian Committee on Hearing Loss in Children (BCHLC)Routine Neonatal Hearing Screening (NHS) is the only strategy capable of early detection of hearing changes which can impact the individual's quality of life. Hearing changes detection process must start with neonatal hearing screening, being followed by diagnosis, hearing aid device fitting and early interventions. The first six months of life are decisive concerning the future development of children with hearing impairmentThe American Academy of Pediatrics recommends the use of electrophysiological methods in NHS programs such as the Brainstem Auditory Evoked Potentials (BAEP) and Evoked Otoacoustic Emissions (EOAE) The most employed and recommended technique for Neonatal Hearing Screening has been Transient Evoked Otoacoustic Emissions, since it uses low intensity acoustic stimuli, involving a broad range of frequencies and for being fast - taking about one minute per earBAEP aims at detecting mild to profound, conductive or sensorineural, uni or bilateral hearing losses. It is a non-invasive procedure, with proper specificity and sensitivity to examine newborns, reporting not only on the electrophysiological thresholds, but also the neurologic maturity as an important indicator, thus considering the growing number of preterm newborns found in the neonatal unitsDiagnosis with early intervention can effectively contribute to improve the child's development when followed by a proper rehabilitation programIn order to achieve a quality monitoring of the neonatal hearing screening, it is necessary to have qualified professionals, control and calibration of the procedures, a database system, planning and evaluation of the proceduresConsidering the lack of a neonatal auditory screening program in the city of Porto Velho, Limiar Clinic implemented the first NHS program in August of 2002, at the Dr. Ary Pinheiro Base Hospital. Limiar is a clinic certified and partner to the Public Health Care System (SUS), specialized in hearing diagnosis and rehabilitation, providing speech and hearing therapy for the state since August of 2001.The NHS program team in Porto Velho was initially made up of two speech and hearing therapists and two secretaries, and there was no database implemented in order to manage the NHS data. Currently, the team counts on four secretaries, ten speech and hearing therapists, two ENT physicians, one social worker, one pediatrician, one neurologist and one psychologist. After many years we noticed the need to implement a database which would provide effective access to data and the follow up of those children who failed NHS.The protocol used in the program has been suggested by the Universal Neonatal Hearing Screening Support Group (UNHSSG)The care for the newborn babies coming from the neonatal ICU and joint quarters happens before hospital discharge everyday of the week.Given the aforementioned and the lack of epidemiological data on hearing impairment during childhood in the city of Porto Velho, the present study aimed at characterizing the neonatal hearing screening program developed at the Clínica Limiar in Porto Velho-RO.This study was approved by the Ethics in Research Committee of the School under protocol # 322/08.Study design: longitudinal historical cohort.The data used in this study was collected from the Hearing Evaluation and Rehabilitation Clinic - LIMIAR, since this institution is responsible for neonatal hearing screening in the city of Porto Velho, state of Rondônia - Brazil. The data was collected from February of 2004 to October of 2006. Our sample involved 6,889 registered patients seen in the Dr. Ary Pinheiro Base Hospital.We used the HITRACK 3.5 database software to manage NHS data. From this software we can obtain the number of newborns (NB) screened in joint quarters and those coming from the neonatal ICU, the number of NB who passed and failed the screening, number of newborns referred for diagnosis, risk indicators belonging to the registered newborns, number of NBs who were diagnosed with hearing impairment, their type and level of impairment.The data collected was then submitted to statistical analysis, for which we used the Two-Proportions Equality Test, the Chi-Squared and the Fisher tests. We established 0.05 (5%) as significance level . All confidence intervals used throughout the study had 95% of statistical confidence.In our database we have 6,889 RNs registered, concerning the period from February of 2004 to October of 2006; 5,271 RN (76.5%) from joint quarters and 1,618 RN (23.5%) from the neonatal ICU. Of the 6,889 (100%) registered RNs, 5,700 (82.7%) passed the Transient Evoked Otoacoustic Emissions test and 1,189 (17.3%) were referred for retesting .Table 1DAmong the 1,189 (100%) RNs who failed screening with OAEs, 900 (75.7%) came for retesting and 289 NBs (24.3%) did not .Table 2DOf all 6,889 registered NBs (100%), 15 (0.22%) had their hearing loss confirmed, 2 (0.03%) coming from joint quarters and 13 (0.19%) from the neonatal ICU . In our Of the 15 NB (100%) who had hearing loss confirmed, 7 (46.7%) had neural hearing loss, 2 (13.3%) had conductive hearing loss and 6 NB (40%) had sensorineural hearing loss . AccordiThe implementation of a HITRACK 3.5 database started in 2008 and, therefore, we are just starting to process the data from these six years of neonatal hearing screening.According to the National Center for Hearing Assessment and Management Utah State University (NCHAM) an effective processing of the information is vital for the early detection and intervention on hearing impairment. Detection, diagnosis and intervention depend on the quick access to information, which is guaranteed by the HITRACK databaseWe noticed that the NHS program in Porto Velho/ RO followed the recommendations present in the literature, and the assessment and care for children with hearing loss are done by a multidisciplinary teamAccording to the Brazilian Committee on Hearing Loss in Children (BCHLC) 5, failure rates can vary between 5 and 20% when the screening is carried out with EOAEs on the first 24 hours of life, dropping to 3% when done between 24 and 48 hours of life. In the present study, 1,189 (17.3%) of the registered NB failed screening in the first stage of the NHS program , matching literature dataA study carried out with 50 newborns during their first days of life and 80 during the second showed that on the second day of life there are significant improvements in the test and lower incidence of artifacts, concluding that the second day of life is a better time to perform the hearing screening in neonates with EOAEIn another study carried out in 2000 there was a significant improvement in the “pass” index of NHS after cleaning the external auditory meatus, and removing vernix. They also detected a reduction in tympanic membrane mobility in 22.7% of the ears tested, showing a significant effect on the “failure” index in hearing screeningIn the present investigation, of the 1,189 NB (100%) who failed the first stage, 900 (75.7%) returned for retesting, showing a rate superior to those obtained in another study, which was of approximately 70%The incidence of significant bilateral hearing loss in healthy neonates is estimated to be between 1 and 3 neonates for every 1,000 birthsIn our study we noticed that of the 15 NB (100%) with confirmed hearing loss, the most prevalent type of HL was neural HL in seven NB (46.7%); however, according to the statistical analysis , it cannWe found that the most prevalent indicator was hyperbilirubinemia, accounting for 33.3% of the cases, representing 0.09% of all registered NB. Newborns with high bilirubin levels who require blood transfusion have a higher risk of developing sensorineural hearing lossA retrospective study involving 1,032 pediatric patients with hearing loss reported 67 cases (6.5%) of severe hyperbilirubinemia in the neonatal period, 30 of these patients had overt neonatal hyperbilirubinemia as the only risk indicator for hearing loss. In 26 of the 30 cases (87%) the otoacoustic emissions (OAE) were not present, while in the four remaining cases (13%) the emissions were detected, despite the absence of BAEP responseOften times, the cause of the auditory neuropathy is unknown, nonetheless, the following conditions may be associated with pediatric hearing neuropathy: hyperbilirubinemia, neurodegenerative disorders, hydrocephaly, and other diseasesMany authors report that the children with the highest likelihood of having hearing loss upon screening are those with family history of congenital hearing loss, craniofacial malformation, low birth weight, anoxia, syndromes, ICU stay for more than 24 hours, hyperbilirubinemia and unknown etiologyIn the joint quarters we identified two NBs with HL of unknown etiology, and such data was statistically significant, justifying the need for universal NHSIn the neonatal ICU we found a higher number of HL (13 NB) since it is a population with risk indicators for hearing loss. This information is statistically significant when compared to the results found from the joint quarters .Table 7HThe rate of newborns who passed the first screening stage was of 82.7%  and 17.3%  failed it. We noticed that among the 1,189 NBs (100%) who were referred for retesting, 24.3% (289) did not come.The hearing loss prevalence seen was of two NBs for every 1,000 births.Hyperbilirubinemia has a higher prevalence among the risk indicators found among NB with confirmed hearing loss. We also noticed a statistically significant correlation between the neural hearing loss and the bilirubinemia risk indicator and sensorineural hearing loss with unknown etiology.The risk indicators for hearing loss in cases diagnosed with hearing impairment were hyperbilirubinemia, unknown etiology, anoxia, craniofacial malformation, inheritance, prematurity/low birth weight, syndrome and congenital infection.Based in the present study, we stress the need for using BAEP in the NHS of NBs with hearing loss risk and to follow these children with confirmed diagnosis of HL up. Health care professionals involved in NHS programs must use a database which may, in the future here in Brazil, help develop a multicentric study on pediatric hearing loss.


Noise-induced hearing loss is a permanent sensorineural deficiency, which is caused by exposure to excessive noise sound. Although noise-induced hearing loss due to industrialization is a main public health problem in Ethiopia, studies on the prevalence and associated factors of hearing loss are scarce.This study aimed to assess the prevalence and associated factors of hearing loss among workers at a metal workshop in Gondar city, Northwest Ethiopia.p < 0.05 were computed to determine the level of significance.A cross-sectional study was employed among 300 participants using a stratified sampling technique. Data were collected using an interviewer-administered questionnaire. Bivariable and multivariable logistic regressions were conducted. In the multivariable logistic regression model, adjusted odds ratios (AOR) with a 95% confidence interval (CI) and a The prevalence of hearing loss among metal workshop workers was 30.7% [95% CI: ]. Age between 30 and 44 years , age between 45 and 65 years , cigarette smoking , working area noise level >85 dB , working experience of 6–10 years , working experience >10 years , and using ear protection devices  were significantly associated with hearing loss.The prevalence of hearing loss was considerably high. This study revealed that advanced age, cigarette smoking, increased working area noise level, and working experiences were found to increase the odds of having hearing loss. Therefore, it is important to emphasize metal workshop workers that are at high risk of hearing loss and develop preventive strategies to reduce the burden of this problem. Besides, minimizing working area noise levels, proper utilization of ear protection devices, and creating awareness about the impact of hearing loss are recommended. Hearing loss is defined as if an individual has a threshold level of ≥25 dBA at the frequencies 250, 500, 1,000, 2,000, 4,000, and 8,000 Hz , 4. IndePrevious studies have confirmed that exposure to a noise level of more than 85 dB can lead to an increased risk of hearing loss . InteresGlobally, about 16% of disabling hearing loss in adults is due to occupational-related noise . StudiesWorkplace noise exposure shows a significant financial and health impact on individuals and society levels , 19. It Based on previous studies, factors that are associated with hearing loss include occupational noise in the workplace , duratioNowadays, hearing loss due to industrialization is a main public health problem in Sub-Saharan Africa, particularly in Ethiopia . AlthougA cross-sectional study was conducted among workers at a metal workshop in Gondar city from March to May 2021. Gondar is one of the historical cities in the country and is located in the Central Gondar Zone of the Amhara National Regional State. It is far around 750 km from Addis Ababa, the capital city of Ethiopia. Based on the Gondar city trade and industry office report, a total of 409 employees are found in 46 metal workshops.All metal factory workers at Gondar city were the source of population. All metal workshop workers who are presented in the study area during the study period were included in the study population.All adult metal workshop workers whose age is ≥18 years and working in the metal factory at least for 6 months were eligible to participate in the study.The sample size of the study was determined using a single population proportion formula by considering: the confidence level (95%), the margin of error = 5%, and the prevalence of hearing loss = 28.2% taken from the previous study done in Nigeria (for this study was hearing loss (yes/no). Socio-demographic factors such as sex, age, educational status, marital status, and monthly income were assessed. Behavioral and working area-related behaviors like cigarette smoking, alcohol intake, utilization of hearing protection devices , work experience, duration of exposure, the intensity of exposure, leisure-time noise exposure, and working area noise level were also assessed.The dependent variable Those workers who were making metal welding, cutting, and reshaping to create useful objects.It was diagnosed if an individual has a threshold level of ≥25 dBA at the frequencies 250, 500, 1,000, 2,000, 4,000, and 8,000 Hz as measured by an audiometer test , and then translated back into English by experts who are fluent in both languages. Participants were interviewed by four Bsc nurses under the supervision of a principal investigator. Two types of instruments used for measuring sound levels were the sound level meter   and the pure-tone audiometer .The environment noise (working area noise level) was measured in work stations using the sound level meter  with a measurement range between 25 and 130 dB. In this study, the sound level meter was calibrated before and after each use and workplace noise level measurements were taken on slow response. The device was placed at an approximate distance of at least 1 m from the noise source. The audiologist holds the device by facing the microphone toward the noise source and observed the measurement on the liquid crystal display. The working area noise level was measured as an average value of 5 measurements hourly throughout working times for 8 h since the production process was inconsistent, and 8-h time-weighted average was taken. Lastly, the mean working area noise level of 8-h time-weighted average on five different days was taken for each working area .Pure-tone audiometer calibration was done daily using supposedly normal people with normal hearing prior to any audiological evaluation of the participants. All audiometric tests were done in a quiet room with a background noise level of 36–40 dB before the workers entered their work stations to avoid the effects of temporary threshold shifts, due to continuous noise exposure inside the working area. Participants were advised of a planned audiometric test, therefore, they can have a “quiet time” or “acoustic rest” of ideally 16 h before the audiometric test . The par2), normal (18.5–24.99 kg/m2), overweight (25–29.99 kg/m2), and obese (≥30 kg/m2).The height of metal workshop workers was measured with calibrated height measuring steel attached to the beam balance in a standing upright position with bare feet. Participants' weight was also measured using a calibrated weight scale and recorded accurately to 100 g. Body mass index was calculated based on the result of anthropometric measurements and it was categorized as underweight . The Hosmer–Lemeshow test was done to assess model goodness-of-fit (p ≥ 0.05). Independent variables having a p ≤ 0.2 in bi-variable analyses were included in the multivariable analysis to control confounders in binary logistic regression models. An odds ratio (OR) at a 95% confidence interval (CI) was determined to see the strength of association between the independent variables and outcome variables. Factors with a p ≤ 0.05 in the multi-variable regression model were considered statistically significant.After data collection, data were entered into Epi data 4.6 and then exported into Statistical Package for Social Sciences (SPSS) version 25 software for analysis. Descriptive statistics  were used to summarize the characteristics of the study population through tables and charts. The normality of continuous data was checked by the Shapiro-Wilk test  of study participants were males. The median age of the participants was 35 years with an interquartile range of 16. Nearly 47% of study participants were unmarried. Regarding educational status, about one-third (35.3%) of participants were diplomas and above. A majority (92.4%) of the participants had a normal body mass index .About one-third (34.7%) of the participants were smokers. One-third (34%) of the participants had more than 10 years of working experience. Among the total metal workers, about 57.3% of participants have not used ear protection devices and nearly half (52%) of the participants were exposed to noise levels >85 dB .In this study, the prevalence of hearing loss among metalworkers was found to be 30.7% . In addition, 23.7% of participants had bilateral hearing loss, whereas 7% had unilateral hearing loss  . RegardiIn the bivariable analysis: work experience, working area noise level, age, cigarette smoking, alcohol intake, listening to music, and use of ear protection devices were significantly associated with hearing loss. However, in multivariable binary logistic regression analysis: only age, working experience, use of ear protection devices, smoking, and working area noise level were identified as statistically significant risk factors for hearing loss .Metal workshop workers in the age group between 45 and 65 years were 3.8 times more likely to develop hearing loss when compared to those in the age group between 18 and 29 years . Similarly, the likelihood of hearing loss among metal workshop workers in the age group between 30 and 44 years was 2.9 times higher compared to those in the age group between 18 and 29 years . Participants who had more than 10 years of working experience were 3.5 times more likely to have a hearing loss than those participants who had 1–5 years . Participants with working experience of between 6 and 10 years were 1.8 times higher to have hearing loss as compared to those participants between 1 and 5 years . Participants who used ear protection devices were 70% less likely to develop hearing loss as compared to those who did not use ear protection devices . Metalworkers who were exposed to a working area noise level of more than 85 dB had 2.2-fold higher odds of hearing loss than those who were exposed to <85 dB . A smoker had a 2.3 times higher chance of developing hearing loss as compared to non-smokers  .The purpose of the present study was to assess the prevalence of hearing loss among metal workshop workers and its associated factors in Gondar city. In this study, the overall prevalence of hearing loss was 30.7% . This finding is similar to previous studies done in Nepal (30.4%) , Rwanda The present study showed that 23.7% of participants had bilateral hearing loss, whereas 7% had unilateral hearing loss (3.7% right ear and 3.3% left ear). The prevalence of bilateral hearing loss in the current finding is lower than the similar findings of a study done in Sudan (62.5%) . In bothIn this study, factors such as age, working experience, cigarette smoking, and working area noise level were positively associated with hearing loss. However, the use of ear protection devices was negatively associated with hearing loss. The current study revealed that metal workshop workers in the age group between 30 and 44 years and 45 and 65 years were more likely to develop hearing loss when compared to those in the age group between 18 and 29 years. This finding is consistent with the previous studies , 42–44. The finding of this study indicated that participants with a working experience of 6–10 years and above 10 years had a higher chance of developing hearing loss than those participants between 1 and 5 years. This is supported by previous literature done elsewhere , 32, 37.via excessive sound  allowing us to generalize the findings to all metal workshop workers in Gondar city. This study has some limitations: First, the study did not show the cause and effect relationship since it is a cross-sectional study design. Second, the study did not address extra working significant exposure. Furthermore, the study will be a base for future investigators to perform better study designs like prospective cohort and experimental studies in this setting to bring findings with better validity.The prevalence of hearing loss among metal workshop workers in Gondar city was relatively high. The study indicated that advanced age, cigarette smoking, high working area noise level, and prolonged working experience were found to increase the odds of having hearing loss among metalworkers. Therefore, it is important to emphasize metal workshop workers that are at high risk of hearing loss and develop preventive strategies to reduce the burden of this problem. This study recommends the proper utilization of ear protection devices. Besides minimizing working area noise levels, proper utilization of ear protection devices and creating awareness about the impact of hearing loss are also recommended.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The studies involving human participants were reviewed and approved by School of Medicine Ethical Review Committee, College of Medicine and Health Sciences, University of Gondar. The patients/participants provided their written informed consent to participate in this study.DA and MM conceived and designed the study, participated in the data collection process, analyzed data, and wrote the manuscript. BM and AA participated in data analysis, drafting of the manuscript, and advising the whole research paper and also were involved in the interpretation of the data and contributed to manuscript preparation. All authors read and approved the final manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer BF declared a shared affiliation with the authors DA, MM, AA, and BM to the handling editor at the time of review.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. 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