Chronic exposure to small amounts of arsenic in drinking water increases a person's risk of cancer and other diseases.
Researchers believe they're now onto an explanation for the process.
Arsenic acts as an endocrine disrupter, upsetting the action of hormones by blocking or mimicking them, say Joshua W. Hamilton of Dartmouth College in Hanover, N.H., and his colleagues. Previously identified endocrine disrupters have included many pesticides, industrial chemicals, and pollutants including dioxin. This is the first time that a metal has joined the list, says Hamilton. The researchers suggest that arsenic interferes with the action of glucocorticoids, hormones never known before to be vulnerable to endocrine disruption by pollution. Glucocorticoids belong to the same family of steroid hormones as estrogen and testosterone.