May 9, 2011

Arsenic in Water Linked to Heart Disease

(Ivanhoe Newswire) -- Exposure to even moderate levels of arsenic in drinking water is associated with an increased risk of heart disease, especially among smokers, according to this study.

High levels of arsenic exposure from drinking water have already been related to an elevated risk of heart disease. Given the huge burden of heart disease worldwide, a small increased risk associated with moderate arsenic exposure could be of major public health importance.

Researchers from USA and Bangladesh, led by Dr Yu Chen from New York University School of Medicine and Dr Habibul Ahsan from the University of Chicago, set out to test the association between arsenic exposure and death from cardiovascular disease and to assess whether cigarette smoking influences the association.

The study involved 11,746 men and women living in Araihazar, Bangladesh, where groundwater is contaminated by arsenic.
Participants were interviewed and underwent a physical examination. Urine samples were also taken and tested for levels of arsenic. This procedure was repeated at two year intervals for an average of 6.6 years.

After adjusting for factors such as age, gender, smoking status and education level, the authors found a dose-response relation between arsenic exposure and deaths from heart disease at a lower level of arsenic exposure than previously reported.
The death rate for cardiovascular disease was 271 per 100,000 person years among individuals drinking water containing moderate levels of arsenic (12 - 864 parts per billion, or ppb) compared with 214 per 100,000 person years among individuals drinking water containing low levels of arsenic (less than 12ppb).

They estimate that almost 30% of these deaths in the study population can be attributable, in part, to moderate levels of arsenic concentrations in well water (12-864 ppb).
The risk of dying from heart disease associated with arsenic exposure was consistently higher in current and former smokers compared with never smokers, suggesting that the cardiovascular effects of arsenic exposure, even at moderate levels, are further intensified by smoking.

Arsenic poses far higher health risks than any other known environmental exposure, say Professors Allan Smith and Craig Steinmaus from the University of California, Berkeley, in an accompanying editorial. Yet water contaminated with arsenic is tasteless, looks crystal clear, and boiling the water only concentrates the arsenic in it.

SOURCE: BMJ, published online May 5, 2011