Breaking hearts with toxics

for the first time, a conclusive link between heart ailments and long-term exposure to arsenic has been established by a study. Carried out by researchers from Taipei-based National Taiwan University, the study strongly points to arsenic as one of the risk factors for diseases related to blood vessels. It indicates that there is a strong dose-dependent relationship between arsenic exposure and accelerated development of atherosclerosis disease in arteries that lead to the brain. "Chronic arsenic poisoning called arseniasis is an emerging epidemic in Asia. Our results indicate that long-term arsenic exposure may lead to the progression or acceleration of diseases in carotid arteries that are located in the neck," said Chih-Hao Wang, the lead author of the study ( www.who.int, March 27, 2002).

During their study, the researchers studied 199 men and 264 women from an area of southwestern Taiwan. The area has high prevalence rate of arseniasis and high rates of blackfoot disease (bfd) -- an unique form of peripheral vascular disease that begins with coldness or numbness in the lower extremities and progresses to block small blood vessels. The researchers also measured the amount of arsenic in well water in the region since the early 1960s. Based on those measurements and detailed questionnaires given to each subject, the researchers calculated the duration and amount of arsenic exposure for each individual. They found that three indices of long-term exposure to arsenic -- how long someone consumed artesian well water, the average arsenic concentration in that water and the cumulative arsenic exposure -- were significantly associated with prevalence of carotid atherosclerosis in a dose-dependent relationship. In other words, the spread of the disease increased with rising levels of arsenic accumulated in the body.

Furthermore, the researchers divided the subjects into three groups based on arsenic exposure levels and found that those with highest exposure had three times the risk of atherosclerosis as people who were not exposed to arsenic. Those in the mid-range of exposure had double the risk than someone who was not exposed. "From the strong dose-dependent relationship, we conclude that long-term arsenic exposure is an independent risk factor for atherosclerosis and that carotid atherosclerosis is a novel marker for arseniasis," said Wang.

However, some experts are not convinced by the findings of the study. "I would view this research with caution. This is an area which should be studied comprehensively before drawing such conclusions, as cardiovascular diseases are a very important cause of mortality," said Antero Aitio, a toxicologist with the World Health Organisation (who).

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