ARSENIC LEVELS IN DRINKING-WATER AND THE PREVALENCE OF SKIN-LESIONS IN WEST-BENGAL, INDIA

Background A cross-sectional survey was conducted between April 1995 a nd March 1996 to investigate arsenic-associated skin lesions of kerato sis and hyperpigmentation in West Bengal, India, and to determine thei r relationship to arsenic water levels. Methods In all, 7683 participa nts were examined and interviewed, and the arsenic levels in their dri nking water measured. Results Although water concentrations ranged up to 3400 mu g/l of arsenic, over 80% of participants were consuming wat er containing <500 mu g/l. The age-adjusted prevalence of keratosis wa s strongly related to water arsenic levels, rising from zero in the lo west exposure level (<50 mu g/l) to 8.3 per 100 for females drinking w ater containing >800 mu g/l, and increasing from 0.2 per 100 in the lo west exposure category to 10.7 per 100 for males in the highest exposu re level (greater than or equal to 800 mu g/l) However, 12 cases with keratosis (2 females and 10 males) were drinking water containing < 10 0 mu g/l of arsenic. Findings were similar for hyperpigmentation, with strong dose-response relationships. Among those with hyperpigmentatio n, 29 cases were exposed to drinking water containing <100 mu g/l. Cal culation by dose per body weight showed that men had roughly two to th ree times the prevalence of both keratosis and hyperpigmentation compa red to women apparently ingesting the same dose of arsenic from drinki ng water. Subjects who were below 80% of the standard body weight for their age and sex had a 1.6 fold increase in the prevalence of keratos es, suggesting that malnutrition may play a small role in increasing s usceptibility. Conclusion The surprising finding of cases who had arse nic-associated skin lesions with apparently low exposure to arsenic in drinking water needs to be confirmed in studies with more detailed ex posure assessment. Further research is also needed concerning suscepti bility factors which might be present in the exposed population.