Scientists, consumer advocates, government officials, and industry representatives gathered Sept. 18-20 in Bethesda, Maryland, to reflect on 25 years of research on chemicals in the environment that may interfere with hormones in the body, known as endocrine disruptors.
“25 Years of Endocrine Disruption Research: Past Lessons and Future Directions,” featured research about health effects from endocrine disruptors and the complex mechanisms that are involved. Attendees also discussed the influence of scientific evidence on the development of new consumer products and safer chemicals. The event was organized by NIEHS as part of its year-long 50th Anniversary celebration.
“We know that endocrine disruptors are implicated in many different health conditions. They are also found in nearly every person tested and often at higher levels in children,” said NIEHS and National Toxicology Program (NTP) Director Linda Birnbaum, Ph.D., in the opening remarks.
Pivotal conference launches new field of research
In 1991, scientists met at the Wingspread Conference Center in Racine, Wisconsin, to discuss growing evidence that exposure to hormone-like chemicals was harming animal and human health. Studies in the 1970s and 1980s found that chemicals such as dichlorodiphenyltrichloroethane (DDT) were interfering with animal reproduction. Researchers also reported that some pregnant women who took diethylstilbestrol (DES), a synthetic estrogen that prevented miscarriage, had daughters with unusual cancers and reproductive system malformations.
“From Silent Spring to Wingspread, these compounds in the environment were understood as poisons,” said Scott Belcher, Ph.D., from North Carolina State University. “After Wingspread, we shifted to the term endocrine disrupting chemicals [EDCs] to acknowledge their complex interactions in the body and the potential for profound consequences because of the crucial role of hormones in development.”
EDCs affect reproductive health and more
Scientists have now linked EDCs, including organochlorine pesticides, polychlorinated biphenyls (PCBs), certain flame retardants, and other substances, to a range of health effects. Niels Skakkebaek, M.D, D.M.Sc., from the University of Copenhagen, discussed links with testicular cancer, reduction of semen quality, and reduced male fertility.
Tracey Woodruff, Ph.D., from the University of California, San Francisco, spoke about the effects on female reproduction, including uterine fibroids, endometriosis, and abnormal development of the ovaries.
“The influence of age at exposure is clear,” said Woodruff, referring to the potentially powerful effects of early life exposures. One study she cited showed that girls exposed to high levels of DDT before age 14 had a five-fold increase in breast cancer risk compared with girls without DDT exposure.
Some endocrine disruptors, called obesogens, may play a role in the obesity epidemic (see sidebar). According to Bruce Blumberg, Ph.D., from the University of California, Irvine, a variety of hormones control appetite, metabolism, fat cell development, and fat storage. He said studies have shown that animals exposed to obesogens in the womb are more likely to be fat, and these effects may be heritable.
Researchers were careful to account for calorie consumption and exercise. “Energy balance by itself is insufficient to explain the rise in obesity,” said Blumberg.
Removing EDCs from consumer products
Industry representatives and advocates described new changes underway, based on these findings. Bill Walsh, J.D., founder of the Healthy Building Network , discussed efforts to remove harmful chemicals from building products. He expressed concern that chemicals no longer used in new materials, like PCBs, may be returned to homes in recycled products.
Katherine Neebe, director of sustainability for Walmart, said that the company implemented a sustainable chemistry policy in 2013 to encourage safer product formulations and transparency about ingredients. Neebe listed eight priority chemicals that Walmart is encouraging its suppliers to reduce or eliminate, and six of them are considered EDCs.
Neebe said that Walmart is also concerned about the possibility of regrettable substitutions, or the replacement of harmful chemicals with chemicals of unknown safety, which may also turn out to be harmful. “We’ve found that you can get customer attention once, and industry can respond and innovate around the concern. But if you don’t fix it correctly, you have a really hard time getting public attention again,” she said.
(Virginia Guidry, Ph.D., is a technical writer and public information specialist in the NIEHS Office of Communications and Public Liaison and a regular contributor to the Environmental Factor.)