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, Calif.
Many of the human body’s processes, 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 manmade 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 more than 100 foreign chemicals in his or her body. In one study of pregnant women, the average woman had 286 such 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 they were 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 as a result of 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, co-authored by Dr. Theo Colborn of the World Wildlife Fund, former Boston Globe reporter Dianne Dumanoski, and Dr. John Peterson Myers, now senior advisor to the United Nations Foundation, numerous human health problems also owe their origins to hormone-disrupting chemicals (see www.ourstolenfuture.org). They include low sperm counts and increased rates of testicular and prostate cancer among men and increased rates of breast cancer, endometriosis and tubal pregnancies in women.
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.