An international team of experts reported today that evidence linking hormone-mimicking chemicals to human health problems has grown stronger over the past decade, becoming a "global threat" that should be addressed.
The report is a joint effort by the World Health Organization and the United Nations Environment Programme to give policymakers the latest information on chemicals that alter the hormones of people and wildlife.
Much has changed since 2002 when WHO and the UN released a report that called the evidence linking endocrine-disrupting chemicals to human health impacts “weak.”
The panel of 16 scientists from 10 nations in North America, Europe, Africa and Asia found that endocrine-related diseases and disorders are on the rise. There is now “emerging evidence for adverse reproductive outcomes” and “mounting evidence" for effects on thyroids, brains and metabolism, according to the report summary.
“Over the past decade, we know much better that chronic diseases, ones related to the endocrine system, are increasing globally,” said Thomas Zoeller, a professor at the University of Massachusetts, Amherst and a co-author of the report.
Such diseases include male reproductive problems, pregnancy complications, certain cancers, obesity and brain development. Many factors can cause such diseases, but the report concludes that given how fast some of these are rising, environmental chemicals are likely playing a role.
Fetuses, babies and young children “are not just little adults” and are the most vulnerable to hormone-altering chemicals since their bodies are still developing, the authors wrote.
Zoeller said the goal of the report is to update world leaders on a topic that is complex and, at times, controversial.
A decade ago the biggest threat was thought to be persistent organic pollutant chemicals – such as DDT and polychlorinated biphenyls (PCBs). These chemicals – now banned in the United States -- traveled the globe, persisted in the environment and caused severe population declines in some wildlife species.
Such contaminants still pose a threat. However, less persistent but more ubiquitous chemicals found in everyday products – such as bisphenol A (BPA) and phthalates – now are increasingly linked to human health problems.
“These chemicals are what we call ‘pseudo persistent,” said Tracey Woodruff, a professor at the University of California, San Francisco, and a report co-author. “They don’t stay in the environment long but people are exposed to them all the time so it’s the same effect as if they were persistent.”
The report points to previous regulations, such as the 2000 U.S. restrictions on chloropyrifos, as an option to protect people. After the pesticide was banned from residential use, children’s blood levels in New York were cut in half within two years. Also, lead bans greatly reduced children’s exposure.
To avoid prolonged exposures in the future, the panel reported that perhaps countries should “ban or restrict chemicals in order to reduce exposure early, even when there are significant but incomplete data.”
“Frankly, for BPA, the science is done. Flame retardants, phthalates … the science is done,” Zoeller said. “We have more than enough information on these chemicals to make the reasonable decision to ban, or at least take steps to limit exposure.”
But government agencies and industry groups remain unconvinced.