Scientists are beginning to study endocrine disrupters in the environment. They are mostly man-made chemicals which can cause a range of defects and diseases by interfering with a body's hormones. Hormones are involved in just about every biological process: immune function, reproduction, growth, even controlling other hormones. Endocrine disrupting chemicals interfere with the signals from the body by sending signals which mimic biological functions at the wrong times. Compounds such as DDT, chlordane, dieldrin and PCBs are known endocrine disrupters. These chemicals are still used extensively in third world countries and are transported long distances in the atmosphere. In industrialized countries, nonylphenols are used as dispersing agents in paper and pulp production, emulsifying agents in paints and pesticides, industrial cleaners, the manufacture of plastics and hundreds of other uses. Of all foods tested, tomatoes and apples have the highest levels of nonylphenols. These levels were attributed to the use of emulsifying agents commonly found in pesticides that are used on the crops (Guenther, et al, 2002, Endocrine Disrupting Nonylphenols are Ubiquitous in Food, Environmental Science and Technology, 36(8), 1676-1680). Large numbers and quantities of endocrine disrupting chemicals have been released into the environment since World War II (Colburn T., Von Saal F., Soto, A. Environmental Health Perspective 101:378-384 1993). Numerous wildlife health problems are associated with exposure to endocrine disrupting chemicals. The physical impairments include abnormal thyroid function, decreased fertility, and decreased hatching success. Recent investigations by U.S. Fish and Wildlife Service contaminant biologists have documented degraded water quality conditions in Las Vegas Wash and Las Vegas Bay of Lake Mead, Clark County, Nevada. The Geological Survey found that water, sediment, and carp tissue there contained elevated concentrations of a variety of known or suspected endocrine disrupters. These include a number of pesticides, industrial compounds, pharmaceuticals and personal care products which have been identified in water, sediment, fish blood plasma and tissues. High concentrations of perchlorate which were found are known to interfere with normal thyroid function in humans. Another Geological Survey researcher reported finding ethynylestradiol, a synthetic chemical typically found in oral contraceptives.

For more information on the U.S. Geological Survey findings for the Las Vegas Wash studies and others go to http://water.usgs.gov/.

Additional information on the topic and a lists of chemicals suspected to be endocrine disrupters can be found at http://www.nihs.go.jp/hse/environ/endocrin.htm.

A National Science Foundation web site http://whyfiles.org/045env_hormone/index.html is a good link for additional reading on the subject of endocrine disrupters.