Spurred by mounting scientific evidence, the U.S. Environmental Protection Agency is initiating a new effort to examine whether low doses of hormone-mimicking chemicals are harming human health and whether chemical testing should be overhauled.
The EPA, responding to a report by a group of 12 scientists published in March, is collaborating with other federal agencies to assess whether the traces of chemicals found in food, cosmetics, pesticides and plastics affect human development and reproduction. As part of that review, they will evaluate whether current testing is capturing effects linked to hormone mimics, and if the agency should alter its risk assessments.
The federal officials will complete a “state of the science” paper by the end of 2013, which then reportedly will be reviewed by a national panel of scientists.
“The state of the science paper findings will provide information to help inform how the safety of chemicals [is] assessed,” according to the EPA website.
“While EPA is interested in all aspects of low dose extrapolation, this short term effort is designed to meet immediate science-policy needs.”
There is longstanding disagreement in the scientific community whether exposure to substances that mimic or block estrogen, testosterone and other hormones leads to human health impacts.
However, a report released in March concluded that small doses can have big effects. For three years, researchers led by Tufts University’s Laura Vandenberg examined hundreds of studies on the effects of endocrine-disrupting chemicals and their report found that the evidence “clearly indicates that low doses cannot be ignored.”
The scientists in that report criticized the federal government’s decades-old strategy for testing most chemicals – exposing lab rodents to high doses then extrapolating down for real-life human exposures. They said it is inadequate to protect people and urged reforms because hormone-like chemicals can have health effects at low doses that do not occur at high doses.
The EPA, in its new effort, will evaluate this phenomenon, which is called "non-monotonic dose response."
“Current testing paradigms are missing important, sensitive endpoints” for human health, the scientists said in their report, published in the journal Endocrine Reviews. “The effects of low doses cannot be predicted by the effects observed at high doses. Thus, fundamental changes in chemical testing and safety determination are needed to protect human health.”
Pete Myers, founder of Environmental Health News and chief scientist at Environmental Health Sciences, was the senior author of the report.
University of Missouri professor Frederick vom Saal, a co-author of the report, said it is about time the government takes low doses seriously.
“I’m thrilled they’re doing this and it’s desperately needed,” said vom Saal, who studies effects of low doses of bisphenol A (BPA) in rodents. “Hopefully it won’t take long and we can stop asking whether there are low-dose effects and then deal with the fact that there are.”
Vom Saal said the EPA and U.S. Food and Drug Administration (FDA) currently makes “very frightening assumptions” about exposures to these chemicals, such as BPA, which is found in canned food liners, polycarbonate plastic and some paper receipts.
“You cannot test a hormone like you would a toxicant,” he said. “A chemical that adds or subtracts to hormones already in your body is going to have effects at low levels.”
Vom Saal said federal agencies have for years determined the safety of endocrine-disrupting compounds without testing them at low levels. “There are no such thing as safe levels when you’re talking endocrine disruptors,” he said.
The American Chemistry Council, which represents chemical companies, did not have time to fully review the new research program on Wednesday so it had no comment, according to a spokesperson.
However, the chemical association in March cited Michigan State University toxicologist Michael Kamrin, who said in a 2007 paper that low-dose effects have not been proven and should not be applied to real-world conditions and human exposures.
The EPA’s newly announced effort was in part spurred by the March report and a failed congressional bill in 2009 that would have bolstered endocrine disruption research.
Vandenberg, lead author of the March report, said the new federal effort is a step in the right direction, but she said she was worried about the conflation of two concepts: low dose and “non-monotonic dose responses.” The EPA’s website includes both.
“Non-monotonic” dose response occurs when humans’ or animals’ responses to chemicals do not necessarily go up or down with the dose – effects can occur at any level. Low dose effect means you see an effect below a certain cutoff.
“They’re two very different things,” Vandenberg said. “I hope they will address both issues – but address them separately. It’s unclear from the website if they will.”
University of California, Berkeley’s Tyrone Hayes, also a co-author on the report, said testing of chemicals “should look at a range of doses. Something may have an effect at a low dose, but you could go even lower, or higher, and find more of an effect, or a different effect altogether.”
In tackling the research, the EPA will work with scientists from the FDA, the National Institute of Environmental Health Sciences’ National Toxicology Program and the National Institute of Child and Human Development.
The EPA has requested that a panel of the National Research Council review its "state of the science" report, which is expected in late spring.
“Results from epidemiological studies suggest an association between environmental (‘low dose’) concentrations of endocrine active chemicals and reproductive or developmental health outcomes,” EPA officials said on its website. “These effects have been examined and reported with mixed results in a wide range of animal studies.”
“EPA is committed to basing its decisions on sound science and to developing this state of the science paper in an open, public participatory and transparent process,” the EPA said.
The EPA also announced this week it would tackle another controversial issue: nanotechnology, specifically whether nanomaterials are harming human health or the environment.
Nanomaterials are tiny materials – about 100,000 times smaller than the width of a human hair – that are increasingly used in clothing, cosmetics, electronics and building materials. The EPA will work with the U.S. Consumer Product Safety Commission to examine if nanomaterials are released from products and how they interact with people and the environment.
“These tiny nanomaterials are widely used in products ranging from clothing to sunscreen, but the need for additional research and knowledge on how they affect consumers is great,” said Dr. Treye Thomas, a program manager for the Consumer Product and Safety Commission, in a prepared statement.
This article originally ran at Environmental Health News, a news source published by Environmental Health Sciences, a nonprofit media company.