Exposure to Arsenic in urban and rural areas and effects on thyroid hormones

Context: Arsenic is a ubiquitous element present in urban air as a pollutant, and it may interfere with thyroid hormones. Objective: To evaluate the association between the personal exposure to arsenic and levels of TSH, fT4, fT3, and Tg in urban and rural workers. Materials and methods: Total urinary arsenic and thyroid markers were obtained from 108 non-smoking traffic policemen and 77 subjects working as roadmen in a rural area. Fifty subjects were monitored to evaluate airborne exposure to arsenic. Results: The mean value of exposure to arsenic was 2.9 mu g/m(3) in traffic policemen, while the mean value was less than 0.1 mu g/m3 in roadmen. The mean values of urinary arsenic (10.4 mu g/g creatinine vs. 5.2 mu g/g creatinine; p = 0.000), TSH (1.6 mu lU/ml vs. 1.3 mu lU/ml; p = 0.006), fT3 (3.5 pg/ml vs. 3.7 pg/ml; p = 0.000), fT4 (1.2 ng/dl vs. 1.3 ng/dl; p = 0.000) and Tg (42.8 ng/ml vs. 36.1 ng/ml; p = 0.04) were significantly different between traffic policemen and roadmen. In traffic policemen, urinary arsenic and arsenic in the air were correlated to the airborne arsenic and TSH values, respectively. Urinary arsenic was correlated to TSH, Tg, fT3, and fT4 values. The multiple linear regression models showed the following associations: i) among urinary arsenic, arsenic in the air and job title; ii) among TSH, fT3, Tg and urinary arsenic; and iii) between fT4 and both urinary arsenic and alcohol intake. Conclusion: These results provide information about the relationship between exposure to arsenic and thyroid markers and may be useful for other categories of outdoor workers who are similarly exposed.