Prevalence of arsenic exposure and skin lesions. A population based survey in Matlab, Bangladesh

Study objective: To assess prevalence of arsenic exposure through drinking water and skin lesions, and their variation by geographical area, age, sex, and socioeconomic conditions. Design, setting, and participants: Skin lesion cases were identified by screening the entire population above 4 years of age (n = 166 934) living in Matlab, a rural area in Bangladesh, during January 2002 and August 2003. The process of case identification involved initial skin examinations in the field, followed by verification by physicians in a clinic, and final confirmation by two independent experts reviewing photographs. The tubewell water arsenic concentrations (n = 13 286) were analysed by atomic absorption spectrometry. Drinking water history since 1970 was obtained for each person. Exposure information was constructed using drinking water histories and data on water arsenic concentrations. Main results: The arsenic concentrations ranged from < 1 to 3644 mg/l, and more than 70% of functioning tubewells exceeded the World Health Organisation guideline of 10 mg/l. Arsenic exposure had increased steadily from 1970s to the late 1990s, afterwards a decrease could be noted. In total, 504 skin lesions cases were identified, and the overall crude prevalence was 3/1000. Women had significantly higher cumulative exposure to arsenic, while men had significantly higher prevalence of skin lesions (SMR 158, 95% CI 133 to 188). The highest prevalence occurred in 35-44 age groups for both sexes. Arsenic exposure and skin lesions had a positive association with socioeconomic groups and achieved educational level. Conclusions: The result showed sex, age, and socioeconomic differentials in both exposure and skin lesions. Findings clearly showed the urgency of effective arsenic mitigation activities.