In Bangladesh, skin heals when arsenic exposure declines.

Jan 15, 2013

Seow, WJ, WC Pan, ML Kile, AA Baccarelli, Q Quamruzzaman, M Rahman, G Mahiuddin, G Mostofa, X Lin and DC Christiani. 2012. Arsenic reduction in drinking water and improvement in skin lesions: A follow-up study in Bangladesh. Environmental Health Perspectives

Synopsis by Beth Feingold

Skin lesions become less severe and heal over time if exposure to arsenic in drinking water is reduced, reports a study from Bangladesh. Discolored patches of skin -- a telltale sign of overexposure to this naturally-occurring element -- are thought to be a first step in cancer development. The findings indicate that public health measures to reduce arsenic in drinking water are effective in that country, where more than 55 million people are exposed to unsafe levels.

Even though it can take years, people can partially or fully recover from the skin lesions brought on by long-term exposure to arsenic. A study from Bangladesh has found that reducing exposures from drinking water significantly curbed the severity and prevalence of the lesions, which can lead to more severe diseases.

The study is one of the first to look at the association between reducing exposures through drinking water and the extent of arsenic-related skin lesions. The discolored patches and growths on the skin are an early and lingering sign of toxic arsenic exposure.

Arsenic is a known carcinogen. In some cases, the skin lesions, patches and growths can turn into skin cancer. Arsenic also is associated with lung, bladder and liver cancers.

Before this study, it was not known if the skin lesions would get better if exposures were reduced or removed.

Arsenic is a natural element found in soils and rocks around the world. Higher level hot spots occur in Bangladesh, West Bengal (India), and, to a lesser extent, in parts of South America and the United States. Tainted drinking water and food crops – such as rice – remain the biggest sources of exposure for most people. This is especially true in Southeast Asia and the Indian sub-continent where rice is a staple part of the daily diet.

The researchers from the United States and Bangladesh measured arsenic levels in the participants' drinking water and in their toenails to determine the drop in personal arsenic intake. Arsenic levels in toenails provide a solid measure of a person's exposure through drinking water.

In the 1970s, Bangladesh dug deep wells to provide safe drinking water. In the process, they traded the public health risk of pathogens in the shallow wells for cancer risks from the naturally occurring arsenic that leaches into the deeper tube wells.

As a result of what is considered one of the greatest environmental health disasters of our time, more than 55 million Bangladeshis are exposed to harmful levels of arsenic in their drinking water. About 46 percent of the country’s population has been exposed to concentrations exceeding the World Health Organization’s recommended limit of 10 micrograms per liter.

Globally, physicians, epidemiologists, behavioral scientists and hydrologists have spent decades trying to figure out how to get clean, potable water to households in light of this reality. In an effort to reverse the problem, Bangladesh is testing drinking water, closing unsafe wells, drilling new safer wells and installing filters.

In this study, the researchers revisited 550 people in Pabna, Bangladesh, who were part of an earlier study in 2001 - 2003. The same group was also part of an arsenic awareness program where they learned about health effects and how to reduce exposures. Between 2009 and 2011, researchers assessed current exposure to arsenic in drinking water and toxicity by remeasuring two major indicators: arsenic levels in toenails and the presence and severity of arsenic skin lesions.

The previous and current levels of arsenic in the drinking water were statistically compared with the levels of arsenic in toenails and the persistence or recovery of skin lesions. The researchers accounted for differences in demographics, medical history, water consumption and lifestyle factors that may otherwise have influenced the results.

They found that some of those with arsenic-induced skin lesions recovered within 10 years when they reduced their exposure to the toxic element. Some of the reductions were due to government remediation and safe water education programs.

But recovery rates varied depending on the severity of the initial exposures. Those with less contaminated drinking water in the 2001 - 2003 portion of the study had lower arsenic levels and five times higher skin lesion recovery than those whose water was very heavily contaminated during that first visit, even though those who drank more tainted water had a greater absolute reduction in arsenic during the eight-year period.

The authors suggest that those with higher arsenic exposure initially may see similar reductions in skin lesions over time. They may need a longer time to do so because they experienced greater toxicity.

Future investigations should address the links between exposure and healing times and whether reducing the severity of skin lesions leads to a reduction in skin cancer.

Overall these results indicate that reducing arsenic in drinking water in Bangladesh should remain a top public health concern for the world.

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