In a study of more than 11,000 people in Bangladesh, research conducted by Columbia University's Mailman School of Public Health has provided evidence that a population exposed to well water with arsenic concentrations of as little as 50 ug/l is at risk for skin lesions.
The report has also concluded that older, male, and thinner participants were more likely to be affected by arsenic exposure.

The team of researchers evaluated the relationship between arsenic exposure from drinking water and premalignant skin lesions over the course of three years. Participants were evaluated for arsenic exposure based on well-water arsenic concentration and usage. " Because of the wide range of arsenic exposure in the study population and the relatively large sample size, we were able to estimate and report dose-response relations even at the very low end of the arsenic exposure range. In particular, arsenic exposure seems to increase the risk of skin lesions at the low end of exposure in this population," said Habibul Ahsan, at the Mailman School of Public Health and principal investigator.

The researchers have indicated that a unique opportunity exists in Bangladesh to study chronic arsenic exposure measured at the individual level, because the majority of the population uses a single well as their primary source of drinking water, while, for example, in the United States, people usually drink water from multiple sources. However, up until now even assessments at the individual level were extremely difficult because exposures measurements were from years past or the Bangladeshi population drank water from multiple sources.

Another obvious difference between the rural population of Bangladesh and other studied populations is that this population consumes a large amount of water, as much as 2.5–3 liters per day on average vs. 1 liter in the United States. Moreover, almost 100 percent of the drinking water for this population comes from one or two wells with relatively stable concentrations of arsenic.

The team of researchers note that skin lesions were less of a factor in the study for females in the study, and this may be due to the tendency of women in rural Bangladesh tend to cover their bodies more extensively than men. " It also is possible that hormonal and other biologic differences between men and women also could be responsible for part of the gender differences in the skin lesion risks," observed Joseph Graziano, at Mailman School.

The study also found some evidence that participants with a higher body mass index ( BMI ) were at lower risk of skin lesions than participants with a lower body mass index. " Lower body mass index reflects poorer nutritional status in rural Bangladesh, which could directly or indirectly influence the effect of arsenic. In particular, poor nutritional status may be associated with lower intake of the antioxidants, folates, and/or dietary proteins necessary for metabolism and detoxification of arsenic in the body, said Ahsan." The influence by gender, age and body mass should be considered in future research and policy decisions."

Skin cancer is the most common arsenic-related cancer. Nearly 100 million people in the world are chronically exposed to arsenic and, therefore, are at increased risk of skin and other arsenic-induced cancers.

The most common route of human exposure to arsenic is through ingesting drinking water that is naturally enriched with arsenic.

Source: Columbia University's Mailman School of Public Health, 2006
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