The Endocrine Disrupter Controversy

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The theory that chemicals in the environment may be disrupting hormones and causing health problems in wildlife and humans was first published in 1992. Since that time, the general concept of endocrine disruption has gone from a radical theory to an accepted fact. Scientists agree that some chemicals mimic or block hormonal effects, that wildlife populations in some contaminated areas have been affected by the endocrine-disrupting effects of chemicals in the environment, and that some humans have been affected in unusual circumstances.

Scientific debates focus on whether there is a risk to the general population of humans and animals from the low levels of endocrine disrupting

THE ENDOCRINE SYSTEM

THE ENDOCRINE SYSTEM

Emberi Szervek

Adrenaline, cortisol, aldosterone (control heart rate, blood pressure, stress response, alertness)

Insulin, glucagon (control blood sugar)

Ovary

(females)

Melatonin (controls sleep, cancer protection, cell repair)

Stimulating and regulating hormones for thyroid, adrenal, testis, ovary; prolactin (milk production), growth hormone, antidiuretic hormone (signals kidneys to concentrate urine)

Thyroid hormones (control metabolism, heart rate, fetal brain development)

Adrenaline, cortisol, aldosterone (control heart rate, blood pressure, stress response, alertness)

Insulin, glucagon (control blood sugar)

Estrogen, progesterone (control fetal development, puberty, menstration, keep bones strong, promote blood clotting)

Testosterone (control fetal development of the male, puberty, sperm production)

source: Adapted from John W. Kimball, Biology Pages. Available from http://www.ultranet.com/~jkimball.

Ovary

(females)

Testis

(males)

chemicals they are exposed to on a daily basis. Some scientists point out that even low levels of endocrine disruptors may have subtle effects on development of the fetus. These scientists point to trends such as apparent increases in rates of birth defects of the penis in infant boys, declining sperm counts in adult men (see the graph), and increasing rates of hormone-associated cancers such as breast, testicular, and prostate cancer. Other scientists point out that most endocrine disruptors are far weaker than our natural hormones, and that most people and animals are exposed to such low levels of the chemicals that they are unlikely to have any health effects. This debate is likely to rage for many years, because the research to prove or disprove health effects from low-dose exposures to common chemicals will be difficult, complicated, and time-consuming.

Because chemicals that are known or suspected endocrine disruptors are used for a wide variety of purposes, it is difficult for people to know how to avoid exposure. Some endocrine disruptors are used as pesticides on food and others are used in certain types of plastics such as polyvinyl chloride (PVC or vinyl). These chemicals are not just found industrial and agricultural products, but also in the runoff of pesticides from treated fields and in the discharge of waste from industrial operations. Certain endocrine disruptors are not used anymore, but their residues linger in the food chain and are consumed by humans in the form of fatty foods. Because it is difficult for people to make decisions as to how to avoid exposure to endocrine disruptors, many environmental health advocates urge the government to regulate these chemicals more strictly.

In 1996 Congress passed the Food Quality Protection Act, changing how the U.S. Environmental Protection Agency (EPA) regulates pesticides and requiring the EPA to develop an endocrine disruptor screening program. The EPA estimates that there are some 87,000 chemicals used in commerce, and admits there is not enough scientific data available to evaluate all potential risks. see also Health, Human; Pesticides; Risk.

Bibliography

Colborn, Theo; Dumanoski, Diane; and Myers, John Peterson. (1996). Our Stolen Future. New York: Dutton.

Schettler, Ted; Solomon, Gina; Valenti, Maria; and Huddle, Annette. (1999). Generations at Risk: Reproductive Health and the Environment. Cambridge, MA: MIT Press.

Internet Resources

Colborn, Theo; Dumanoski, Dianne; and Myers, Jonathan Peterson. Our Stolen Future Web site. Available from http://www.ourstolenfuture.org.

Environmental Concepts Made Easy Web site. Center for Bioenvironmental Research, Tulane and Xavier Universities. Available from http://www.som.tulane.edu/ecme.

Solomon, Gina M., and Schettler, Ted. (2000). "Environment and Health: 6. Endocrine Disruption and Potential Human Health Implications." Canadian Medical Association Journal 163(11):1471-1476. Also available from http://www.cma.ca/cmaj.

Swan, S.H.; Elkin, E.P.; and Fenster, L. (1997). "Have Sperm Densities Declined? A Reanalysis of Global Trend Data." Environmental Health Perspectives 105(11): 1228-1232.

Gina M. Solomon and Annette Huddle

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