Effectiveness of a medical surveillance program for the prevention of occupational asthma caused by platinum salts: a nested case-control study.

BACKGROUND: Exposure reduction has proven to be effective in the prevention of occupational asthma. Few data are available on the effectiveness of secondary prevention programs, including medical examinations and removal of workers from exposure sources after detecting symptoms or signs indicative of a beginning disease. OBJECTIVE: We sought to assess the effectiveness of a medical surveillance program in workers with exposure to platinum salts. METHODS: A nested case-control study was performed in 14 workers of a catalyst production plant whose skin prick test (SPT) responses to platinum salt converted from negative to positive during a 5-year prospective cohort study with yearly medical examinations and 42 matched control subjects from the plant who did not experience SPT response conversion. With the exception of 2 subjects, the workers showing SPT response conversion were removed completely from exposure sources and followed for up to 42 months. RESULTS: Work-related new symptoms were reported by 9 of the 14 subjects, and new symptoms without relation to work were reported by 3 subjects at the time of SPT response conversion. Symptoms were not accompanied by a change in FEV(1) or bronchial responsiveness to histamine. Symptoms resolved after transferral, but occasional shortness of breath or wheeze persisted in 4 subjects. SPT reactions decreased or became negative in all workers after complete removal but remained unchanged in a craftsman with ongoing occasional exposure to contaminated materials. CONCLUSION: Although no randomized intervention was performed, this study proves the effectiveness of a medical surveillance program for the prevention of occupational asthma caused by platinum salts.

Exposure-effect relationship of platinum salt allergy in a catalyst production plant: conclusions from a 5-year prospective cohort study.

BACKGROUND: There is a high incidence of occupational asthma and rhinitis caused by platinum (Pt) salts in precious-metal refineries. OBJECTIVE: We sought to assess exposure to Pt salts and the incidence of Pt salt allergy in a catalyst production plant. METHODS: A 5-year prospective cohort study was performed in 159 catalyst production workers (94.6% of recruited), 50 craftsmen (92. 6% of recruited), and 66 control subjects (76.7% of recruited) at yearly intervals. Subjects were assigned to exposure categories of high levels of Pt (n = 115), persistently low levels of Pt (n = 51), intermittently low levels of Pt (n = 61), or no Pt (n = 48) after the initial survey according to job title and job location. Skin prick test conversion from a negative response to a 4 mm or larger wheal response with a 10(-2) mol/L hexachloroplatinic acid solution was chosen as the outcome variable. RESULTS: Exposure assessment of airborne Pt and Pt in the serum of workers demonstrated clear differences between exposure categories. The threshold limit value of 2 microg/m(3) for soluble Pt was exceeded in 3 (4%) of 78 measurements. Thirteen subjects assigned to high exposure showed skin test conversion, and new allergic symptoms were associated with exposure. Among the high-exposure category, the incidence rate of skin prick test conversion was 5.9 per 100 person-years for newly employed subjects (n = 79) and 2.1 per 100 person-years for those who had already been employed at the time of the initial survey (n = 36). A predicting factor for skin test conversion in highly exposed subjects was smoking status (relative risk, 3.9; 95% confidence interval, 1.6-9.7) but not atopy or bronchial hyperresponsiveness. CONCLUSION: Sensitization to Pt salts may develop in workers of catalyst production plants. Both the exposure to Pt salts and the incidence of Pt salt allergy were lower compared with reported data from precious-metal refineries.

A cross sectional study of chemical industry workers with occupational exposure to persulphates.

OBJECTIVES: Hair bleaches containing persulphates have been identified as the cause of occupational asthma in hairdressers. Also employees in persulphate production with occupational asthma have been described. It was the aim of this study to give an estimate of the prevalence of asthma due to persulphates in chemical workers with exposure to ammonium and sodium persulphate. METHODS: A cross sectional study was performed in 32 of 33 employees of a persulphate producing chemical plant. Eighteen of 23 workmen from the same plant with no exposure to persulphates were taken as controls. Also, information was collected from medical records of the seven subjects who had left the persulphate production for medical reasons since 1971. Data were recalled by a questionnaire, skin prick tests were performed with five environmental allergens, and ammonium and sodium persulphate (80 mg/ml). Specific immunoglobulin E (IgE) to the same environmental allergens as in the skin test, and total IgE were measured. Lung function and bronchial responsiveness to histamine were assessed by standard procedures. Workplace concentrations of ammonium and sodium persulphate were estimated by area and personal monitoring. The amount of persulphate was analysed as sulphur by inductively coupled plasma emission spectrometry. RESULTS: Work related rhinitis was reported by one subject with exposure to persulphates, conjunctivitis and bronchitis were reportedly related to work by two controls. There were no cutaneous reactions to persulphates in either group. Four non-atopic subjects exposed to persulphates, and two controls, one atopic and one non-atopic, were considered to be hyperresponsive to histamine. Three subjects exposed to persulphates with bronchial hyperresponsiveness (provocation dose of histamine causing a 15% fall in forced expiratory volume in one second (PD15 FEV1) < or = 1 mg) did not show variability in peak expiratory flow of > or = 20%, the rest refused peak flow measurements. None of the variables showed significant differences between the groups (P > 0.05). Six of the exworkers left because of work related contact dermatitis. Mean values for workplace concentrations of ammonium and sodium persulphate within the bagging plant were below 1 mg/m3, and the maximal concentrations were 1.4 mg/m3 and 3.6 mg/m3, respectively. CONCLUSION: Exposure to workplace concentrations of ammonium and sodium persulphate of about 1 mg/m3 in this chemical plant was not associated with a risk of occupational asthma.