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EPA Acknowledges Low Dose Effects, Defends Its Current Testing Protocol

(Beyond Pesticides, June 28, 2013) The U.S. Environmental Protection Agency (EPA) released a draft “State of the Science” report last week acknowledging that low dose responses “do occur in biological systems” while defending its current risk assessment procedures as adequate for evaluating low dose effects. This report comes after EPA’s long running failure to fully implement a 1996 Congressionally mandated program to evaluate endocrine disruptors, and heavy criticism last year from prominent scientists who said EPA’s testing procedures are outdated.

In 1999 the Natural Resources Defense Council (NRDC) filed a lawsuit against the EPA for failing to meet a statutory deadline for implementation of the Endocrine Disruptor Screening Program (EDSP) required under the 1996 Food Quality Protection Act, forcing the EPA to make a settlement agreement. As a result of NRDC et al. v. EPA (No. C-99-03701 CAL) filed in the Northern District of California, EPA agreed to start requiring screening and testing of certain chemicals varying by date, using a tiered system.

EPA’s two-tiered screening and testing system, requires that EPA will identify which chemicals are able to interact with the endocrine system in Tier 1. Tier 2 screening process was designed to go one step further, requiring EPA to determine endocrine effects at various doses. EPA is currently developing Tier 2 tests as well as selecting chemicals for screening. Despite the statutory mandate to screen chemicals for potential endocrine disrupting effects, EPA has yet to regulate endocrine disruptors through a finalized Endocrine Disruptor Screening Program (EDSP) and testing procedures.

In its draft report, EPA acknowledges for the first time that low dose responses to hormone altering chemicals “do occur in biological system but are generally not common.” The report states that low dose responses observed in endocrine endpoints may be biologically relevant and should be evaluated in contest with the totality of the available scientific data, including epidemiologic and human studies. While this is a great step forward for advancing science at the agency, especially when it comes to evaluating endocrine disrupting effects, the agency defended its current risk assessment procedures saying: “There currently is no reproducible evidence [that low dose responses] are predictive of outcomes that may be seen in humans or wildlife populations for estrogen, androgen or thyroid endpoints.”

The report is written by EPA, with input from the Food and Drug Administration (FDA), as well as input from the National Institute of Environmental Health Sciences, and the National Institute of Child Health and Development, both of which review the science on endocrine-disruptors. The report will also be peer reviewed by the National Academy of Sciences.

Last year, a team of 12 scientists who study hormone-altering chemicals, led by Laura Vandenberg, PhD,  Tufts University’s Levin Lab Center for Regenerative and Developmental Biology, criticized EPA ‘s outdated testing methodologies . The scientists focused on the importance of “non-monotonic dose response” which demonstrates that some chemicals can act irregularly with greater health impacts at low doses. Generally, EPA tests the impact of high doses on humans and the environment and then extrapolates the results for exposure at lower doses. Currently, EPA uses high dose testing to predict low dose safety despite the research that shows many hormone altering chemicals do not act according to normal dose curves.

EPA’s report was praised by the American Chemistry Council, an industry-led group representing 135 chemical companies that has periodically launched campaigns to delay the release of EPA’s chemical risk assessment.Meanwhile many scientists have given EPA faint praise and much criticism. Dr. Vandenberg acknowledged that EPA’s admission that non-monotonic responses exist was a step in the right direction. However, the conclusion that high dose responses can predict for safety standards at low doses, “flies in the face of our knowledge of how hormones work,” said Dr. Vandenberg to Environmental Health News. Endocrine disruptors “are overtly toxic but act like hormones with completely different actions at low doses.”

Dr. Vandenburg also criticized EPA for using outdated science on atrazine, rather than using the multitude of current and new publications that show the, “consistent, low-dose effects of this chemical on amphibians, reptiles, fish, birds and mammals.” Similarly, the reports’ discussion of low-dose effects of bisphenol A—a common additive to plastic containers, toys, and receipts—on prostate, “are also about a decade out of date, and give credence to industry funded studies that had flawed experimental designs and failed positive controls,” she added.

Putting these chemicals through more rigorous testing that include low dose responses is in the interest of protecting human health and the environment.  “Accepting these phenomena should lead to paradigm shifts in toxicological studies, and will likely also have lasting effects on regulatory science,” wrote Dr. Vandenberg’s team.

On June 14, 2013, EPA made available the list of commercial chemicals identified for endocrine screening, which include 109 chemicals, 41 of which are pesticide active ingredients.  However, it remains unclear whether low dose effects of hormone altering drugs has been or will be integrated into the screening process. On June 25, 2013 they made that list open to a 30 day public comment period after which the OMB will initiate a review.  The review is the final step before EPA can actually begin issuing orders to chemical and pesticide manufacturers. See EPA’s EDSP webpage.

The annoucnment follows a May 2011 Inspector General report, EPA’s Endocrine Disruptor Screening Program Should Establish Management Controls to Ensure More Timely Results, that found that EPA had missed all its deadlines to implement the law. The report found that, “Fourteen years after passage of the FQPA [Food Quality Protection Act] and Safe Drinking Water Act amendments, EPA’s EDSP has not determined whether any chemical is a potential endocrine disruptor.

For more information on the effects of pesticides on human health, including endocrine disruption, see Beyond Pesticides’ Pesticide Induced Diseases Database.

Source: Environmental Health News

All unattributed positions and opinions in this piece are those of Beyond Pesticides.


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