Dear Earth Talk: Can you explain what "hormone disrupting" chemicals are, how they affect our health and what they have to do with environmental problems?
— Tom Rose, Oakland, CA
Many of the human body's process, including reproduction, mental processing and metabolism, are controlled and regulated by hormones, chemical "messengers" produced by the endocrine glands. In the embryo and fetus, hormones guide the development of the brain, the nervous and immune systems, the sexual organs, and the liver, blood and kidneys, among other organs and tissue. Hormones work by attaching to "receptors," molecules on cell surfaces that carry information into the cells, triggering certain actions. In recent years, scientists have found that certain man-made chemicals disrupt this process by blocking it altogether, throwing off the timing — or by actually mimicking natural hormones and binding with the cells themselves. Such chemicals have been dubbed "hormone disruptors."
Since the 1940s thousands of chemicals have been released into our air, water and food. Chemicals now contaminate virtually every corner of the globe, and the average person has over 100 chemicals in his or her body. In one study of pregnant women, the average woman had 286 chemicals in her fetal blood.
Many of the worst chemicals have been banned or phased out, but they continue to linger in the environment and will no doubt do so for centuries to come. Among the worst culprits in hormone disruption are: PCBs, used heavily in the electrical industries until banned in 1978; phthalates, still widely used in the plastics industry; and dioxin, one of the most hazardous of all chemicals, a byproduct of paper-bleaching, waste incineration and coal-burning, among other industrial activities.
The effects of this growing "chemical soup" were first noticed in wildlife. Alligators in Florida's Lake Apopka, for example, have been unable to reproduce in recent years due to underdevelopment in young males. North Sea seals exposed to synthetic chemicals have also developed reproductive problems as well as suppressed immune systems. And gull colonies in California and elsewhere suffered significant population losses after exposure to chemicals interfered with their reproductive capabilities.
According to Our Stolen Future, coauthored by Dr. Theo Colburn of the World Wildlife Fund, former Boston Globe reporter Dianne Dumanoski and Dr. J.P. Myers, now Senior Advisor to the United Nations Foundation, numerous human health problems also owe their origin to hormone disrupting chemicals. They include low sperm count and increased testicular and prostate cancers among men, and increased rates of breast cancer, endometriosis and tubal pregnancies in women. "What we're talking about is an overall low-dose exposure and a cumulative effect," says Holly Lucille, author of Creating and Maintaining Balance: A Woman's Guide to Safe, Natural Hormone Health.
With so many chemicals permeating our environment, it is almost impossible to attribute specific health problems to specific substances. Individuals can hedge their bets by eating organic and choosing personal care and household products that avoid chemicals. They can also pressure their elected representatives as well as business leaders to work to reduce the amount of pervasive chemicals in the environment.