NRDC raises concerns about potential health effects of herbicide

News
Apr 13, 2012
by DTN

The Environmental Protection Agency (EPA) denied a petition last Monday seeking cancellation of all registrations for the popular herbicide ingredient 2,4-dichlorophenoxyacetic acid, or 2,4-D, used on millions of U.S. farm acres to control broadleaf weeds.

The chemical 2,4-D has been used in the U.S. since the 1940s, according to the American Chemical Society. It is found in about 600 products registered for agricultural, residential, industrial and aquatic uses.

In a petition filed on Nov. 6, 2008, the National Resources Defense Council (NRDC) asked EPA to cancel all product registrations and revoke all legal residue limits in food for the herbicide.

“After considering public comment received on the petition and all the available studies, EPA is denying the request to revoke all tolerances and the request to cancel all registrations,” EPA said in a news release last Monday.

The chemical is a broadspectrum herbicide used to control broadleaf or dicot weeds primarily in monocot or grass crops. It primarily is used as an herbicide sold under a variety of brand names used in agriculture on turf, pastures, cereal grains, corn and sorghum crops. Beyond agriculture, the herbicide is popular for use in residential and commercial lawns and also in aquatic environments.

Dow AgroSciences is currently developing a 2,4-Dtolerant trait system to provide farmers an alternative herbicide system for the management of resistant weeds, The components of Dow Agroscience’s Enlist Weed Control System are pending regulatory approval. Anticipated U.S. commercial launch is 2013 crop year for corn, 2015 crop year in soybean and 2016 crop year in cotton. The regulatory approvals for the complementary Enlist Duo herbicide—a proprietary blend of glyphosate and 2,4-D choline—are also under way.

EPA completed a review of the registration and on the safety of the tolerances for 2,4-D, finding that all products containing 2,4-D are eligible for re-registration.

“During the recent review of the petition from NRDC to revoke the tolerances, EPA evaluated all the data cited by NRDC and new studies submitted to EPA in response to the re-registration decision,” EPA said in the news release.

“Included in the new studies is a state-of-thescience extended one-generation reproduction study. That study provides an indepth examination of 2,4-D’s potential for endocrine-disruptor, neurotoxic and immunotoxic effects. “This study and EPA’s comprehensive review confirmed EPA’s previous finding that the 2,4-D tolerances are safe.”

Tyler Wegmeyer, director of congressional relations for the American Farm Bureau Federation, said the decision is important for agriculture.

“This is good news for farmers and ranchers;” he said, “2,4-D is a very common and important systemic herbicide used to control broadleaf weeds for use on a variety of field, fruit and vegetable crops. It is good to see that EPA conducted a thorough evaluation of all the available data, the public comments and various new studies and found there to be no safety concern.”

Gina Solomon, physician and NRDC senior scientist, said EPA didn’t consider numerous studies provided by NRDC.

“The EPA sat on the petition for over three years, and finally reached a decision that fails to give adequate weight to dozens of studies linking 2,4-D exposure to cancer and birth defects,” she said in a statement.

“And with companies now petitioning the USDA to sell genetically modified crops that would dramatically expand the use of this dangerous pesticide, the EPA’s decision could lead to major problems in the near future.”

NRDC made the request based on studies addressing endocrine effects on wildlife species and the inadequacy of personal protective equipment for workers.

“The flaw in NRDC’s petition with regard to its request to cancel all 2,4-D registrations is that it addresses only 2,4-D’s potential harm without addressing whether that harm is likely to occur or whether it would be unreasonable when weighed against 2,4-D’s benefits,” EPA said in a denial letter sent to NRDC April 7.

The NRDC petition claimed 2,4-D has the potential to cause endocrinedisrupting effects and that EPA should have quantified the risks. In addition, NRDC alleged that factors EPA did not consider would enhance workers’ exposure to 2,4-D.

“Again, NRDC’s assertion falls short of addressing other elements necessary for a complete risk assessment process or risk-benefit balancing,” EPA said in the letter to NRDC.

NRDC points to what it said is a variety of health concerns that led to the group’s attempts to decrease the use of 2,4-D.

“Over the past 40 years, dozens of studies have been published on the links between 2,4-D and non-Hodgkin’s lymphoma, as well as soft-tissue sarcoma in humans,” NRDC says on its website.

“In 2010, approximately 65,540 people in the United States were diagnosed with non-Hodgkin’s lymphoma. The rate of this disease in the United States nearly doubled since the 1970s, even when adjusted for population size and age. It is reasonable to conclude that 2,4-D is likely a contributing factor to cases of non-Hodgkin’s lymphoma.”

NRDC also points to studies that found that 2,4-D enters maternal milk and semen.

“Dozens of peer-reviewed studies show that 2,4-D exhibits hormone-disrupting activity, including estrogenic, androgenic, and anti-thyroid effects. The studies show that 2,4-D affects progesterone, which plays a role in the female menstrual cycle, and prolactin, which plays a role in lactation.”

The group says the chemical also affects the function of the neurotransmitters and hormones dopamine and serotonin.

“Interference with these hormones can cause serious and lasting effects during fetal and infant development, including birth defects, neurological damage in offspring, and changes in reproductive function such as suppression of sperm production,” NRDC says on its website. —Todd Neeley, DTN

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