alt=E-cigarette emissions machine with heat-not-burn<unk>  products. The emissions of four heat-not-burn<unk>  products can be generated in parallel in an emissions experiment. The emissions generated are analyzed using appropriate analytical techniques, which allows a comparison of different applications and products. A 2016 Cochrane review found it unclear if the use of<unk> s (HTPs) would "substantially alter the risk of harm" over traditional cigarettes. , it is impossible to quantify the health risk from using these products, as there is very limited information available on health effects. It is unclear as to what the short- and long-term adverse effects are. , a limited number of independent studies have been conducted on HTPs, and further research will likely increase understanding of health effects. The different types of available HTPs vary in effect, creating a challenge for researchers. It is unknown how users evaluate product safety—one study found that about half of people believed they are safer than traditional cigarettes. A 2016 World Health Organization report stated that claims of lowered risk or health benefits for HTPs compared with traditional cigarettes were based on industry-funded research, and compelling independent research was unavailable to support these claims. It also noted evidence that HTPs may be as dangerous as traditional cigarettes. Action on Smoking and Health in the UK stated in 2016 that due to "the<unk>  industry's long record of deceit" regarding the health risks involving smoking, it is important to conduct independent studies into the health effects of<unk>  products. With an assorted range of electronic cigarettes devices available in the UK, it is unclear if HTPs offer any favorable benefit as a plausible harm reduction product. A 2018 Public Health England report states that HTPs may be much safer than traditional cigarettes but less safe than e-cigarettes. In a 2017 non-technical summary written by the Committee on Toxicity, it recommends that smokers completely stop, even though it found HTPs to be less harmful than smoking. Emissions<unk> s expose the user and bystanders to an aerosol. The aerosol contains levels of nicotine, volatile organic compounds, and carcinogens comparable to regular cigarettes; they have also been found to contain more acenaphthene than regular cigarettes. Other traditional cigarette emission substances such as tar, nicotine, carbonyl compounds (including acetaldehyde, acrolein, and formaldehyde), and nitrosamines are also found in HTPs. A 2017 study found a 10% rise in carbon monoxide and formaldehyde air levels when HTPs were used indoors. Another 2017 study discovered HTPs generated emissions of metal particulates, organic compounds, and aldehydes, and suggests that HTPs generate less concentrations of airborne contaminants in indoor places in comparison to a traditional cigarette, though their use still reduces indoor air quality. A 2018 Public Health England report found that "compared with cigarettes,<unk> s are likely to expose users and bystanders to lower levels of particulate matter and harmful and potentially harmful compounds (HPHC). The extent of the reduction found varies between studies." It also noted that the evidence indicates that less nicotine was inhaled from HTPs than cigarette smoke, and exposure to mutagenic and other harmful substances is lower than with traditional cigarettes, though reduced exposure to harmful substances does not correlate with health risk severity. Even low exposure can increase the risks for cancers, stroke, and other cardiovascular diseases compared to non-smokers. Lower levels of harmful emissions have been shown, but lowering the risk to the smoker who transitions to using them has not been shown, as of 2018. In 2017, the Committee on Toxicity found that HTPs do not reduce exposure or potential addiction to nicotine; some of the substances inhaled from using these products are carcinogens. Physiological changes in response to<unk><unk>  emissions, such as multiple organ system inflammation, energy metabolism, and carcinogenesis, have not been well characterised due to limited research in this area, especially in animal models. A 2018 in vitro study suggested a less harmful pathophysiological response in human organotypic oral epithelial cultures when exposed to such emissions. A 2016 animal study showed that<unk><unk>  emissions did not increase surfactant lipids and proteins, inflammatory eicosanoids and their metabolic enzymes, and several ceramide classes in HTP-exposed mice when compared with their counterparts that were exposed to cigarette smoke. It also discovered that even with reduced toxicants in HTP emissions, overuse (40<unk>  sticks per day) can still lead to eosinophilic pneumonia in humans. The impact on the overall population is unclear. Studies on second-hand HTP emissions as of 2018 were diverse and largely affiliated with manufacturers. There is disagreement over the extent to which HTPs generate air emissions, and the emissions' composition. There is anticipated to be a reduced risk to bystanders where smokers were using<unk> s instead of smoking. Limited evidence on air emissions suggests that toxic exposure from HTPs is greater than from e-cigarettes. There is no safe level of exposure to harm carcinogens, making it difficult to assess how much HTPs reduce health risks. Addiction and quitting HTPs contain the highly addictive chemical nicotine. The nicotine content between HTP and traditional cigarette emissions are in similar ranges, which suggests a similar addictiveness and dependence potential. There is insufficient evidence on the efficacy of<unk> s on quitting smoking. A 2018 World Health Organization report states that "conclusions cannot yet be drawn about their ability to assist with quitting smoking (cessation), their potential to attract new youth<unk>  users (gateway effect), or the interaction in dual use with other conventional<unk>  products and e-cigarettes." In 2017, the Ministry of Health in New Zealand stated that "there is limited information on product use, including whether smokers are likely to switch completely from<unk>  smoking or use both types of product, as well as initiation by non-smokers (including young people)." In 2017, the Committee on Toxicity stated "the Committees were concerned over the potential for non-smokers including children and young people, who would not otherwise start to smoke cigarettes, to take up using these products as they are not without risk." The availability of flavours in HTP products may appeal to non-smokers, and evidence suggests that individuals who have never used<unk>  products, especially children and adolescents, could be susceptible to new products that could lead to the use of traditional cigarettes. In 2017, the Committee on Toxicity noted that "committees were particularly concerned for young people, who do not smoke, starting to use these products, due to the potential for longer exposure over the remainder of their lives compared to adults and to possible differences in sensitivity." The dual use of HTPs and combustible products is common. Trying an HTP was more frequent among adults below the age of 30 and regular traditional cigarette users. A 2015 online survey found that 6.6% of 8240 respondents had tried an HTP at least once. Research demonstrated that there is a high overlap between HTP users and female smokers. According to four epidemiological papers, 10–45 per cent of non-smokers use these products, and show the effectiveness of the marketing of the<unk>  industry; for example, the HTP known as IQOS acts more as a gateway to traditional cigarette use (20% of users) than as a means of quitting (11% of users), and is not anticipated to have a lowered risk among dual users who make up the remaining 69%. In 2016 Philip Morris International (PMI) acknowledged that IQOS is probably as addictive as<unk>  smoking. IQOS is sold with a warning that states the best option is to avoid<unk>  use altogether. IQOS can record the user's smoking habits. While Philip Morris International stated it only retrieves the data when the product is not working properly, Gregory Connolly, a professor at Northeastern University who has studied IQOS, said that<unk>  companies like PMI would have a "mega database" of Americans' smoking habits, and possibly "reprogram the current puffing delivery pattern of the IQOS to one that may be more reinforcing and with a higher addiction potential". As of July 2017, not many US adults had tried using an HTP; approximately one in twenty US adults (including one in ten traditional cigarette users) have heard of HTPs. In Italy, HTP use was 1.4% among the people and 3.1% among regular<unk>  users. A 2018 survey in Italy found that 45 per cent of people who experimented with the IQOS and 51 per cent who were interested in the product had never smoked before. Therefore, such a product may represent, at least in Italy, a gateway for nicotine addiction among never-smokers rather than a harm reduction substitution for current smokers. In Germany, HTP use is not common and is generally more frequent among richer and educated smokers. Since its sale in Japan in 2014, HTP use has been high; A 2017 survey in Japan found that of those who used the IQOS within the last month, 20 per cent had never smoked before. The products did not satisfy 86 per cent of users, and they did not quit using traditional cigarettes; they used both. HTP
Heated tobacco product
Modified risk tobacco product
Smokeless tobacco
Tobacco smoke
Dissolvable tobacco
Ultra-processed food
Herbal smokeless tobacco
Chewing tobacco