Issues > July 14, 1997 (#42) > Hand-Me-Down Poisons: An Update on Hormone Disruption

Hand-Me-Down Poisons: An Update on Hormone Disruption

When Amanda Sherman's mother took the drug diethylstilbestrol (DES) in the early 1950s, she thought she was doing the best thing for her unborn child. In those days, DES--a synthetic chemical that mimicked the body's natural estrogen--was prescribed widely to prevent miscarriages. But Sherman, when she reached her teens, began to develop severe gynecological problems. FDA issued a DES warning in 1971, too late for women like Amanda Sherman, now president of DES Action. Today, ten million people live with the effects of DES taken by their mothers.

"Many women were rendered infertile as a result of DES exposure," Sherman says. DES daughters also suffer increased rates of miscarriages and vaginal and cervical cancers. DES sons are more likely to have genital abnormalities and low sperm counts. In 1979, a new case of transplacental exposure was observed when women in Taiwan who'd consumed cooking oil contaminated with polychlorinated biphenols (PCBs) later had children with birth defects. In the U.S. in the 1980s, the children of women who'd eaten PCB-contaminated fish were found to suffer from low birth weight and neurological impairment. By age four, the children of women with the highest PCB levels had lower scores than others in verbal and memory tests.

What is going on here? Both DES and PCBs are hormone disruptors, chemicals that alter the body's normal hormonal activity. According to Robert Kavlock, Ph.D., director of the reproductive toxicology division of the EPA, the causes and effects of hormone disruption are "probably the number one environmental issue in toxicology right now."

Potential Health Risks

Because the effects of exposure may not show up for at least a generation, DES, PCBs, and other such chemicals have been called "hand-me-down poisons" by the authors of Our Stolen Future, a landmark book on how hormone disruptors in the environment can undermine the reproductive health of animals and, possibly, of humans. Examples of the damage to wildlife are tragically abundant, including sterility in Florida's bald eagles, abnormally small penises in alligators, and reproductive failure in minks fed PCB-contaminated fish from the Great Lakes.

As for human beings, we know that we are exposed to hormone-disrupting chemicals, which appear in everything from plastic to pesticides. In February 1996, the British Medical Journal reported a 25% decline in sperm counts over a twenty-year period in Scottish men, confirming earlier Danish evidence that men born later in the 20th century have lower sperm counts than their forebears. While exposure to hormone-disrupting chemicals was not looked at in these studies, most of these chemicals have only come into existence post-World War II. In April 1997, toxicologist Devra Lee Davis, Ph.D., M.P.H., of the World Resources Institute told Science News, "even low concentrations of these things could be of great concern." Davis speculated that the combined effects of different environmental hormone disruptors may account for increases in human couples' infertility.

Very recent human studies give more cause for concern. In March 1997, scientists at the University of Iowa found that women working on farms were from two to 20 times as likely to experience infertility as other women. "Those who work in agricultural environments," explained the researchers, "have higher exposure to pesticides, many of which have the potential for causing adverse reproductive outcomes." An April 1997 study of 17,000 girls, with data from over 200 pediatricians, reported that many American girls are reaching puberty earlier. Fifteen percent of the white girls and 48% of the African American girls studied were beginning to develop breasts and/or pubic hair by age eight, and in a few cases, as young as three. The study, published in Pediatrics, recommends that "the use of certain plastics and insecticides that degrade into substances that have estrogen-related physiological effects on living things be investigated." It also cites a previous study that examines the possible hormone-disrupting effect upon African-American girls of "hair products containing estrogen or placenta."

Evidence of human reproductive harm is beginning to accumulate, case by case, just as it had for wildlife when Theo Colborn, co-author of Our Stolen Future, started looking at the data a decade ago. As early as 1991, in the "Wingspread Consensus Statement," a group of top scientists declared that "humans may be at risk to the same environmental hazards as wildlife" from hormone disruptors. A March 1997 EPA interim report identified abnormal sexual development, reduced male fertility, and immune system suppression among possible human health effects of hormone disruption, and urged further research.

How Are We Exposed?

In both humans and wildlife, exposure can occur through several pathways, including diet. "A lot of chemicals dissolve in fat and stay there awhile, and so are transferred from animal to animal along the food web," says Peter de Fur, Ph.D., a comparative biologist at the Center for Environmental Studies in Richmond, Virginia. Residues of DDT and PCBs, both banned in the U.S., still appear in human and animal body fat--even in Arctic polar bears.

How many hormone disruptors are out there? In the absence of an "official list," Dr. de Fur estimates that most scientists can agree on "about seventy chemicals that are known to be or likely to be reproductive or developmental disruptors." Known hormone disruptors include such pesticides as atrazine, chlordane, chlordecone, DDT, DDE, and lindane; and industrial byproducts like dioxins, furans and PCBs. Other probable hormone disruptors include alkylphenol ethoxylates (APEs) and their breakdown products (especially nonylphenol) found in some detergents and shampoos, phthalates (used as a dispersant in some insect repellents and to soften PVC plastic), and bisphenol-A found in dental sealants and the linings of some food cans. A 1997 study at the University of Missouri showed that daily exposure of mice embryos to bisphenol-A produced permanent changes in the endocrine system. In April, the presence of bisphenol-A and nonylphenol in the soil of south Texas was linked to the region's high incidence of neural birth defects.

Despite widespread persistence of hormone-disrupting chemicals in the environment, most knowledge of the impact on humans comes from acute exposures, like DES, or accidental poisonings, as with the Taiwanese cooking oil. "We know that effects can occur if exposures hit a certain level," Dr. Kavlock says. While scientists do not yet know for certain how dangerous low-level environmental exposures might be, Our Stolen Future urges a precautionary approach, maintaining that persistent hormone-disrupting chemicals should be phased out and the burden of proof (of harmlessness) shifted to industry. If human beings and animals may be vulnerable to the same chemicals, how long must we wait for regulation?

Government Action

Both the 1996 Food Quality Protection Act and the amendments to the Safe Drinking Water Act require the EPA to develop a screening and testing strategy for hormone disruptors by August 1998, to implement the strategy the following year, and to submit a progress report to Congress by 2000. To help meet these requirements, the EPA has founded the Endocrine Disruptor Screening and Testing Advisory Committee (EDSTAC), with over forty members from government, science, industry, and environmental groups.

The EPA has also commissioned the National Academy of Sciences to do a thorough review of all scientific knowledge on hormone disruptors--including how they impact wildlife and humans--and to recommend priorities for research and testing. "Before, cancer was the scareword," says Dr. Kavlock. Now, testing that looks at effects on several generations "will do a much better job of describing the potential toxicity of pesticides and other chemicals."

In other words, the government is finally taking a closer look at the ability of hormone-disrupting chemicals in the environment to harm our littlest ones, in keeping with the EPA's newly-announced focus on children's health as the criteria for environmental regulation. In May, an international panel of environmental ministers agreed to a U.S.-sponsored proposal that pledges increased research on hormone disruptors. "These chemicals are distributed globally now," notes Peter de Fur. "If the U.S. decides to act, it needs to be together with other countries," Dr. Kavlock agrees.

Public Campaigns

A few European governments have already acted. Denmark and Switzerland have placed restrictions on APEs. In the U.S., the campaign against hormone disruptors thus far has mostly been waged by citizens and consumer groups.

At the Washington Toxics Coalition (WTC), Phil Dickey compiles information on products that contain APEs and their alternatives, and then alerts manufacturers. Greenpeace and the Citizens Clearinghouse for Hazardous Waste campaign against dioxins released in the production of PVC plastic, chlorine-bleaching of paper, and incineration of medical waste. The Ecology Center of Ann Arbor is pushing Michigan to switch to chlorine-free paper in state government offices. In Washington State, the WTC and other groups are seeking "zero discharge" language for hormone disruptors in clean water laws.

One critical national policy initiative involves the work of scientists like Gina Solomon, M.D., M.P.H., of the Natural Resources Defense Council, to expand the Toxic Release Inventory (TRI). The nation's biggest right-to-know act, the TRI forces companies to provide information on the chemicals they release into the environment. Currently, only a third of known or suspected hormone disruptors are covered by the TRI; dioxin, nonylphenol and bisphenol-A are not. "If there's any suspicion that a chemical is an endocrine disruptor, the public needs to be told when they might be exposed," says Dr. Solomon.

In other words, chemicals should be assumed guilty until proven innocent--by both consumers and regulators. "While it is important to do more research, we shouldn't let that stop us from taking action where we do have alternatives," says Mary Beth Doyle of Ann Arbor's Ecology Center. Some of these alternatives appear below.

- Jennifer Starrels is a freelance writer living in Brooklyn, New York. Lisa Y. Lefferts, M.S.P.H., was research consultant for this article.