RESUMO
OBJECTIVE: To establish the occupational exposure limit for trimethyltin chloride(TMT) in workplace air. METHODS:According to the GBZ/T 210.1-2008 Guide for Establishing Occupational Health Standards--Part 1: Occupational Exposure Limits for Airborne Chemicals in the Workplace, the relevant literatures on toxicology, population epidemiology and foreign occupational exposure limit of TMT were collected and analyzed. A total of 276 workers with TMT occupational exposure were selected as the exposure group and 25 workers without TMT occupational exposure were selected as the control group.Worksite survey of occupational health and occupational medical examination were carried out. Combined with the literature data, the occupational exposure limit of TMT in the workplace air was calculated by using the 90% medical reference level(internal exposure limit) of the urine TMT level of workers who exposed to TMT without moderate hypokalemia. RESULTS: The time-weighted average of TMT in the workplace air is 0.100 mg/m~3 and the short-term exposure limit is 0.200 mg/m~3 in the United States based on total organic tin. The highest concentration of TMT in the workplace air in Germany is 0.005 mg/m~3. The literature data analysis results showed that the incubation period of TMT poisoning is mostly 3-6 days, and the main symptoms of TMT poisoning are hypokalemia in the early stage, followed by neuropsychiatric symptoms such as headache, memory loss and aggressive behavior. The median(M) and the 0-100 th percentile(P_0-P_(100)) of exposure to TMT were 8.35(< 0.20-91.40) μg/m~3 in the exposure group. The individual TMT exposure level of workers in different positions from high to low were crushing, granulation, withdrawal and assembly positions. The M(P_0-P_(100)) of urinary TMT level in the exposure group was 16.94(<0.50-591.14) μg/L. There was a positive correlation between the individual TMT exposure level and urine TMT level in the exposure group(Spearman correlation coefficient=0.62, P<0.01). The detection rate of hypokalemia in the exposure group was higher than that in the control group(26.1% vs 4.0%, P < 0.05). However, there was no significant difference in the detection rate of moderate hypokalemia between the two groups(3.3% vs 0.0%, P>0.05). The 90% medical reference value of urine TMT was 89.90 μg/L in workers exposed to TMT without moderate hypokalemia. CONCLUSION: In order to prevent acute hypokalemia damage caused by TMT, we recommended that the occupational exposure limit of TMT in the workplace air should be set at 0.025 mg/m~3 in China, and this limit should be the maximum allowable concentration.