Arsenic Exposure and Sensory Neuropathy

Joseph H. Graziano, Ph.D.
Mailman School of Public Health, Columbia University
P42ES10349 and P30ES09089

Background: In the 1960s, the World Health Organization started a campaign to drill wells in Bangladesh to provide fresh drinking water. The impetus for this effort was to prevent high rates of childhood mortality from diarrheal diseases caused by microbial contamination of surface waters. However, this well-meaning public health intervention has had drastic consequences. Many of the inexpensive ”tube” wells are contaminated with the metal arsenic at levels much higher than the current U.S. standard of 10 micrograms per liter. Arsenic is a known carcinogen and also causes diabetes, skin lesions, and a deforming condition known as blackfoot disease. Recent studies indicate that it may cause cognitive deficits in children similar to the effects of lead poisoning.

Advance: NIEHS-supported researchers at Columbia University have been investigating the health effects of arsenic exposure, the geological causes of the well contamination, and methods to prevent the exposure. In the health effects arena, they have recently described the first controlled studies of adverse effects on the peripheral nervous system caused by arsenic. In the experiments, the study subjects were asked to identify which of two metal rods was vibrating, a standard test of sensory perception. Measurements were taken on the right index fingers and left big toes. The researchers found that cumulative arsenic exposure and urinary arsenic levels were both significantly associated with the inability to correctly identify the vibrating rod. Specifically, as arsenic exposure increased, the amount of vibration necessary for the subject to make the correct determination increased.

Implications: These findings add to the body of knowledge that chronic arsenic exposure through contaminated drinking water is associated with sensory peripheral neuropathy. Further research is necessary to elucidate a true dose-response relationship, but this study shows a clear connection between individual arsenic exposure and adverse nervous system effects.

Citation: Hafeman DM, Ahsan H, Louis ED, Siddique AB, Slavkovich V, Cheng Z, van Geen A, Graziano JH. Association between arsenic exposure and a measure of subclinical sensory neuropathy in Bangladesh. J Occup Environ Med. 2005 Aug;47(8):778-84.