Case Report of Occupational Asthma Induced by Polyvinyl Chloride and Nickel
A 34-yr-old male had been employed for 7 months at a wallpaper manufacturing factory immediately after moving from the roller processing industry. He had suffered from a cough and chest tightness after engaging in mixing PVC dust into plasticizers and pulverized stone powder for 4 months. When he visited the emergency room with dyspnea in October 2011, he was diagnosed with an acute asthma attack based on wheezing, a forced expiratory volume in one second (FEV1) value that was 74% of the predicted value and 90% sputum eosinophils. He had no relevant medical history or family history of allergic diseases. Chest X-ray showed no abnormalities. Blood tests revealed a WBC count of 8,200/µL (neutrophils 61.1%, lymphocytes 27.6%, eosinophils 4.4%) and a hemoglobin level of 14.2 g/dL. The serum total IgE level was increased to 246 IU/L (reference range 0-114 IU/L), but skin prick tests with 55 common inhalant allergens were negative. Intradermal tests with 0.1 mg/mL PVC elicited a positive reaction, with a wheal size of 13×10 mm and surrounding erythema of dimensions 24×23 mm. A prick test using PVC gave a negative response. Patch tests with PVC, zinc oxide, Ni and chromium showed a positive result for only Ni at 48 hr.\nThe patient achieved well-controlled asthma with an inhaled corticosteroid and a long-acting beta agonist and was then hospitalized for a specific inhalation challenge test. The methacholine challenge test was positive, with a PC20 value of 2.5 mg/mL. A bronchial challenge test with saline was negative. On the second day, a specific bronchial challenge test in which the patient transferred PVC dust (about 200 mL) between two trays for 2 hr was performed. He complained of coughing and mild itching on his hands, but no significant change in lung function was detected, even the fractional concentration of exhaled nitric oxide (FeNO) was increased. On the third day, a 3-hr bronchoprovocation test with PVC dust was performed using the same procedure. The FEV1 value started to fall about 10 min after exposure and reached a maximum decrease of 19.5% from baseline at 1 hr after exposure (). Several wheals developed on the patient's extremities and abdomen and resolved spontaneously on the day after the exposure. An approximate twofold increase in FeNO (from 29 ppb at baseline to 55 ppb 4 hr after challenge) occurred after a bronchial provocation test with PVC. However, the patient did not expectorate sputum at that time. On the fifth day, a bronchial provocation test with Ni was performed by nebulizing 10-3, 10-2, 10-1, 1, and 10 mg/mL Ni sulfate. A maximum reduction in FEV1 (23.2%) was noted about 17 hr after exposure (). The sputum eosinophil count increased from 2% at baseline to 79% 15 hr after the provocation test.\nBased on these findings, the patient was diagnosed with OA caused by both PVC and Ni. After the patient terminated his employment, he had no asthma symptoms and achieved normal pulmonary function through continued inhaled corticosteroid treatment.