Our Scientific Goals
A close look at arsenic
The primary focus of Dartmouth's Toxic Metals Research Program is arsenic, and all of our research projects are examining arsenic in detail. Individual projects are also investigating several other toxic metals in the environment, including chromium, nickel, cadmium, mercury, cobalt and lead.
In particular, we want to know:
- The natural and man-made sources of arsenic in the environment and their relative contributions to human exposure;
- how arsenic and other metals move through ecosystems;
- whether arsenic at levels found in drinking water in the U.S. raises the risk of cancer and other diseases in humans; and
- precisely how arsenic affects the cellular processes that are known to contribute to cancer and heart disease.
As a collective goal, we hope to identify sensitive biomarkers for arsenic - molecular changes that act as warning flags indicating that cells have been exposed, affected or are particularly susceptible to damage by arsenic or other harmful metals. Developing biomarkers will contribute to a better understanding of the way arsenic affects living systems and will be useful in monitoring exposure in people and the environment.
Why arsenic?
Exposure to arsenic in drinking water represents a significant health problem for people around the world. In 1997, the World Health Organization recommended that arsenic in drinking water be recognized as a major public health issue that should be addressed on an emergency basis. The United States Environmental Protection Agency (EPA) has proposed lowering the maximum acceptable level of arsenic in drinking water, which is now 50 parts per billion.
Arsenic is ranked first by the U. S. Centers for Disease Control and Prevention on a list of 50 chemicals of most concern for human health. Arsenic also tops the U.S. Environmental Protection Agency's list of chemicals of concern at toxic waste sites.
In humans, exposure to arsenic has been linked to increased risk of cancer, heart disease, diabetes and reproductive disorders. However, most studies linking arsenic with human disease have involved people exposed to very high levels - in the workplace, for example, or in parts of Taiwan, Pakistan and other areas of the world where levels of arsenic in drinking water are unusually elevated. In Bangladesh, India, an estimated 70 million people have been slowly poisoned by well water tainted by arsenic from natural sources deep within the ground.
Scientists have very little direct information about the effects of arsenic exposures at levels found commonly in the United States. In addition, the way arsenic interacts with other substances in biological systems - such as the cells in human bodies - is poorly understood. These questions are important in guiding public policy on setting acceptable levels of exposure to arsenic from public sources, such as tap water.
Arsenic in New Hampshire
Soils and waters in New Hampshire have been found to contain levels of arsenic that are substantially higher than those found in other regions of the United States. We have focused our geological, environmental and human health studies principally on New Hampshire. Other states in which there are areas unusually high in arsenic include Maine, Massachusetts, Michigan, California, New Mexico, Arizona, Colorado and Nevada.