By Pat Rizzuto
May 2 --A draft Environmental Protection Agency report failed to prove the agency's chemical testing strategy would detect health or ecological harms that may result from exposure to chemicals that mimic, block or alter how hormones work in animals and people, a National Academies critique said.
EPA's draft report did not provide sufficient evidence to support its conclusion that its chemical testing strategies are adequate, the academies' National Research Council said in the critique published May 2.
The EPA issued a statement that the draft report the academies critiqued was not evaluating whether the agency's chemical testing strategy would detect harm from exposure to chemicals that mimic how hormones work in the human body. The agency said the academies' critique commended the EPA for undertaking the challenge of examining nontraditional ways some scientists say endocrine disruptors are affecting the body. The academies recommendations will help make the agency's science stronger, EPA said.
The National Research Council report said the EPA should develop a plan to analyze the adequacy of its testing strategies, explain what its strategies are, and clearly describe how it reaches its conclusions when it eventually does.
The critique did not evaluate whether endocrine disrupting chemicals cause harm. Instead, the academies focused on the procedures the EPA used and the scientific rationale it provided in its draft report.
The academies critique may play a role in the debate over regulatory strategies for endocrine disruptors. The American Chemistry Council and other trade associations have flagged potential differences between the United States and European Union regulatory approaches as an issue the governments should tackle in the ongoing Transatlantic Trade and Investment Partnership negotiations.
European Union regulations on endocrine disruptors could affect up to $4.8 billion in agricultural exports from the U.S., according to a November 2013 report funded by CropLife America, which represents pesticide makers .
Decisions about the doses at which alleged endocrine disruptors cause harm and the resulting regulatory approaches the governments take to prevent such harms could affect trade worldwide, not just U.S.-European transactions, Herbert Estreicher, an attorney with Keller and Heckman LLP, has told Bloomberg BNA .
In addition to trade concerns, the issue of regulating endocrine disruptors has broad health implications. For example, a medical and scientific organization called the Endocrine Society issued a statement in 2009 that said:
“The evidence for adverse reproductive outcomes (infertility, cancers, malformations) from exposure to endocrine disrupting chemicals is strong, and there is mounting evidence for effects on other endocrine systems, including thyroid, neuroendocrine, obesity and metabolism, and insulin and glucose homeostasis.”
The EPA asked the National Academies to convene a panel to critique the agency's draft 2013 report, State of the Science Evaluation: Nonmonotonic Dose Responses as They Apply to Estrogen, Androgen, and Thyroid Pathways and EPA Testing and Assessment Procedures.
In that draft report, the EPA concluded its testing strategy for endocrine disruptors is highly unlikely to miss problems people or wildlife would experience following their exposure to such chemicals .
EPA's report did not define a specific testing strategy, but referred generally to the testing and risk assessment approaches used, for example, in its Endocrine Disruptor Screening Program.
Among its recommendations, the academies said the EPA should specify the toxicity-testing strategies it considered and evaluate them clearly to determine whether they would pick up the doses at which endocrine disruptors may cause their effects.
The concept of nonmonotonic dose responses (NMDR) is that some chemicals, such as endocrine disruptors, may cause harm at doses that traditional toxicity tests and risk assessment approaches would fail to detect.
The reason is that toxicologists using the internationally approved toxicity tests that regulators require typically use only a few doses to ascertain whether a chemical is causing harm. Based on the data from those tests, risk assessors draw straight lines, which presume there is no safe dose, or they conclude that high doses might cause harm, but that there is a dose at which point the line flattens, because below that point an organism would not be harmed (threshold assumption).
The implication of a curved, V-shaped, U-shaped or other nontraditional nonmonotonic dose response curve is that the traditional testing and risk assessment approaches could conclude a chemical is safe when it is not.
“If current testing strategies are inadequate to account for nonmonotonic dose response relationships, changes in risk-assessment practices might be necessary,” the academies said.
However, “the existence of nonmonotonic dose responses has been controversial for decades,” the academies report said.
The academies commended the EPA for taking on the challenge of examining nonmonotonic dose responses and determining whether the agency's testing strategy would detect two different issues: 1) whether nonmonotonic dose response relationships occur and, if so, 2) whether traditional tests and risk assessment approaches would miss harms that could occur.
“This is one of the few attempts to evaluate specifically the implications of the evidence on NMDR curves for testing strategies and risk-assessment practices, and the agency is to be commended for undertaking such a challenging task,” the academies said.
The academies advised the EPA to develop a clearly described plan to analyze NMDR curves and the adequacy of detecting them with current tests.
The agency should include evidence from human studies as it conducts its analysis, the academies said. The EPA's draft report did not include human studies among the scientific research it examined.
Laura Vandenberg, an assistant environmental health professor at the University of Massachusetts, Amherst, said the academies' critique echoed many concerns the Endocrine Society raised when it evaluated the EPA's draft report
The academies critique underscores a challenging issue that regulatory, academic, industry and other scientists must address, she said.
Internationally approved “guideline studies,” have value because they can be replicated by laboratories all around the world, Vandenberg said.
But the data generated through non-guideline studies also warrant consideration, she said. Such non-guideline studies are among the sources of toxicity tests that showed nonmonotonic dose responses.
Richard Becker, the American Chemistry Council's senior toxicologist for regulatory and technical affairs, and Ellen Mihaich, scientific coordinator for the Endocrine Policy Forum, which is managed by CropLife America, said the academies report doesn't address the adequacy of EPA's approach to testing chemicals.
The academies' critique urges the EPA to do a better job evaluating the science on nonmonotonic dose response and to better explain what tests it uses to determine whether such nontraditional responses cause harm.
Those recommendations back concerns previously raised by the academies about the agency's failure to examine scientific studies consistently, and to transparently explain how it reaches its conclusions, Becker said.
EPA's approach to identifying harm caused because a chemical affects the endocrine system is fundamentally sound, provided the agency continues to improve its methods as additional science and better testing methodologies are developed, Becker said.
Mihaich said the agency's risk-based strategy is essential.
She agreed with the chemistry council's recommendation that governments, including the U.S. and European Union, develop harmonized approaches to assessing the risks of endocrine disruptors.
While policy discussions continue, some companies already are providing the agency with toxicity information in the first, or screening, phase of the EPA's Endocrine Disruptor Screening Program, which is designed to detect possible endocrine disruptors.
Bayer Cropscience LP, Dow Agrosciences LLC, Dupont and Tide International USA Inc. are among those companies.
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The academies will post its critique, Review of the Environmental Protection Agency's State-of-the-Science Evaluation of Nonmonotonic Dose-Response Relationships as They Apply to Endocrine Disruptors, at http://www.nap.edu/catalog.php?record_id=18608.
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