Dartmouth team studies arsenic effect

Sunday News Staff
February 18, 2001

Arsenic has been known to spoil even the most unselfish efforts to better the human condition.

Over the past 20 years health authorities campaigned to get the people of Bangladesh to stop drinking untreated, waste-contaminated surface water. They drilled deep wells to tap the bedrock for clean drinking water for millions who live in one of the world's poorest nations.

By the mid-1990s, however, scientists began finding evidence that high levels of arsenic, released to groundwater under naturally occurring aquifer conditions, is poisoning thousands of people in Bangladesh and West Bengal.

Natural arsenic contamination of drinking water supplies also is a problem in New Hampshire, which was known as the "arsenic state" in the 1800s when its mines met the nation's need for a chemical used in products as diverse as paint, pesticide and lead shot, in which it was a hardening agent.

A study by the U.S. Geological Survey has identified southeastern New Hampshire as an arsenic hotspot, with more than 20 percent of the public bedrock wells in that region showing concentrations of arsenic above the Environmental Protection Agency's new drinking water standard of 10 parts per billion (ppb).

The state Department of Environmental Services has estimated the arsenic in 15 percent of the deep artesian wells in New Hampshire exceeds the 10 ppb action level. Of the New Hampshire wells that have been tested, the majority with elevated readings are in the 10 ppb to 100 ppb range, but some have been found to have arsenic concentrations as high as 500 ppb.

The sinister value of a relatively large amount of arsenic — a lump the size of a pea is deadly — has been known since ancient times when some unscrupulous types rose to power and fortune by adding a dash of the colorless, odorless, tasteless substance to the food they fed their rivals.

In lesser amounts — there are documented accounts of mass poisonings in Taiwan, India and South America that involved continual ingestion of as little as 50 ppb — arsenic has been linked to an increased risk of cancer, diabetes and heart disease.

Dartmouth College scientists, backed by a $15 million federal grant, will take a comprehensive look at arsenic and other toxic metals over the next five years. The Toxic Metals Research Program involves more than 60 Dartmouth faculty, physicians and staff from 14 departments. Their work is expected to help shape national policy on the relationship between health and exposure to toxic metals.

They are comparing how natural and man-made sources of arsenic contribute to human exposure; plotting how arsenic moves through ecosystems, and studying whether arsenic at levels found in drinking water raises the risk of diseases in humans, and precisely how arsenic affects the cellular processes that are known to contribute to cancer and heart disease.

Program Director Joshua W. Hamilton heads a team examining whether arsenic and chromium act as "endocrine disrupters" that indirectly modify the way cells behave and increase their probability of becoming cancerous.

Among the other projects:

-- Pharmacologist Aaron Barchowsky is focusing on how the arsenic in drinking water narrows blood vessels, causing disease.

-- Geologist C. Page Chamberlain is measuring the amount of arsenic in New Hampshire's bedrock and investigating how it got there. The project evolved from a graduate seminar Chamberlain led in which students analyzed samples of rock from more than 300 of the state's old arsenic mine sites. Some samples were found to contain arsenic at concentrations 100 times higher than is normally found in the Earth's crust.

-- Earth scientists Joel D. Blum and Carl E. Renshaw are concentrating on the hydrogeological conditions that cause arsenic to flow from bedrock to groundwater and through groundwater to well water. They are also assessing how much of the arsenic found in well water leached from polluted dump sites.

-- Epidemiologist Margaret R. Karagas is searching for a link between arsenic in New Hampshire well water and the state's cancer rates. Karagas and her colleagues will measure individual exposures to arsenic and determine whether those exposures correlate with confirmed cases of skin cancer.

It is the first-ever study of the effects of arsenic at levels between 5 ppb and 50 ppb and is viewed as important for establishing a scientifically-sound safe drinking water standard for arsenic.

copyright 2001, Union Leader