Expert Views :: The Search to Understand Endocrine Disrupting Chemicals
Wendy Hessler

The search to understand endocrine disrupting chemicals (EDCs); unravel their mysteries; and find a fast, affordable way to screen and test for them continues at breakneck speed. Every year researchers delve into everything from molecular mechanisms to ecosystem dynamics to learn how these complex and widespread compounds function. EDCs, so named for their ability to interfere with hormone signals, include a wide variety of substances found in common products like pesticides, plastics, and detergents. Many new discoveries that may lead to better understanding were put forth at e.hormone 2001 and other recent conferences.

One of the most intriguing e.hormone presentations suggested that ecosystem disruption might be occurring in a plant community. Jennifer Fox and colleagues found that certain pesticides and estrogenic chemicals blocked about 90 percent of chemical signals between special nitrogen-fixing bacteria and plant root cells that use converted atmospheric nitrogen to build proteins. Cutting off this essential plant function slows or can stop plant growth. In short, applying pesticides to crops may severely impact fixation and require nitrogen fertilizers to promote plant growth, setting up a cycle of pesticide/fertilizer applications. The bottom line: plants, too, are vulnerable to endocrine disrupting effects that not only affect organisms but can broadly interfere with chemical communications essential to healthy, functioning ecosystems.

Another suite of talks at e.hormone focused on the increasingly understood and very important role of genes and hormones (especially estrogen) in male sexual development. Researchers discovered estrogen in the adult male reproductive tract in the late 1970s but did not start understanding its function until just 10 years ago. Now, researchers know that estrogen is essential for normal development of male sex organs and reproductive health. Many abnormalities ranging from cancer to intersex individuals (a combination of male and female external organs/internal anatomy) to infertility result from too little or too much estrogen during development. In short, environmental estrogens, such as diethylstilbestrol (DES), may contribute extra boosts of hormone-like signals that can derail normal genetic control of prenatal sex determination (male or female) and differentiation (cells divide and become certain organs).

Presentations at other conferences found that drinking water and sewage water contain pharmaceutical drugs and everyday chemicals, some of which are endocrine disrupters. Thirty-eight different chemicals were found in sewage wastewater but only trace amounts of some of them were detected in drinking water, says a Science News article reporting about October’s Conference on Pharmaceuticals and Endocrine Disrupting Chemicals in Water (Science News, 160:285). Of 42 prescription/over-the-counter drugs screened for, 17 made it through the wastewater treatment process while only two were found in trace amounts in drinking water. Presentations at November’s Society for Environmental Toxicology and Chemistry (SETAC) meetings also found many chemicals in sewage treatment effluent sampled from Boston and New York facilities. Full secondary treatment reduced amounts and concentrations of some EDCs compared to plants with only partial secondary treatment. These findings suggest that although many chemicals and drugs contaminate sewage wastewater, correct treatment methods at both sewage and drinking water treatment plants can prevent many of them from getting into the environment.

This is just a sampling of the newest findings in the world of EDC research. The mid-December international EDC conference in Japan and the e.hormone 2002 conference in October of 2002 in New Orleans prove to yield more interesting and perhaps surprising results. For now, look for more detailed reviews of e.hormone and SETAC meeting presentations on the Environmental Estrogens and Other Hormones web site in December.