Low arsenic levels in drinking water linked to skin lesions

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Even low levels of arsenic in drinking water can increase the risk of premalignant skin lesions, according to the results of study based in Bangladesh.

Exposure to low levels of arsenic in drinking water is a problem for millions of people around the world. The health consequences of this, however, were unclear as most studies investigating the effects of low-dose exposure have simply extrapolated the data from high-dose studies.

Dr. Habibul Ahsan, from Columbia University Medical Center in New York, and colleagues selected Bangladesh as the study site because most individuals there have been exposed to a wide range of arsenic levels in drinking water over a long period of time. Nearly 12,000 subjects were recruited from 2000 to 2002 for the present analysis, the Health Effects of Arsenic Longitudinal Study (HEALS).

Well-water arsenic concentrations, well usage patterns, and urinary arsenic levels were used to estimate arsenic exposure from drinking water.

The researchers' findings appear in the American Journal of Epidemiology for June 15.

The greatest risk of a premalignant skin lesion, either melanosis or hyperkeratosis, occurred with the highest arsenic levels (175.1 to 864.0 micrograms of arsenic per liter of drinking water). Such levels increased the risk of skin lesions by 5.39-fold relative to levels < 8.1 micrograms/liter.

However, the risk of skin lesions also increased with much lower arsenic levels. For example, people exposed to drinking water with arsenic levels of 8.1 to 40.0 micrograms/liter were 91% more likely to have skin lesions than those exposed to lower levels.

Male gender, older age, and lower BMI all seemed to increase the effect of arsenic exposure on skin lesion risk, the report indicates.

The authors note that arsenic levels of up to 50 micrograms/liter of water are permitted in Bangladesh and, until very recently, in the US as well. The present findings suggest, however, that these levels of arsenic may still give rise to premalignant lesions.