The EPA tested the active and inactive ingredients of 52 pesticide chemicals evaluated under the Endocrine Disruptor Screening Program (EDSP). The results of the tests are in direct conflict with a large body of scientific evidence that has specified that herbicides including 2,4-D and atrazine, act as endocrine disruptors.
The testing system by the EPA was designed to require that the EPA identify which chemicals interact with the hormone (endorcrine) system; specifically with three hormonal pathways, estrogen, androgen and thyroid. The purpose of the tier 1 screening data is to evaluate whether a chemical has the potential to interact with the endocrine system and requires additional testing.
The EPA results specified that there was no evidence for the potential interaction with any of the endocrine chemicals for 20 chemicals that were evaluated. Fourteen chemicals did reveal potential interaction. Of the remaining 18 chemicals, EPA found that all showed potential interaction with the thyroid pathway, 17 of them with the androgen (male hormones) pathway, and 14 also potentially interacted with the estrogen (female hormones) pathway. While most of the chemicals were not recommended for additional testing, some, such as captan, cypermethrin, dimethoate, and linuron, were recommended for specific Tier 2 tests. A comparative thyroid assay was recommended by the agency for four chemicals that showed interaction with the thyroid pathway in mammals, a medaka one-generation reproductive test was recommended for 13 chemicals that showed interaction with the estrogen or androgen pathways in wildlife, and a larval amphibian growth and development assay was recommended for five chemicals that showed interaction with the thyroid pathway in wildlife.
Even when the agency did determine that there was interaction with both the estrogen and androgen pathway, as was found with atrazine, the agency did not recommend it for further testing stating that it is not expected to impact on human or environmental health. The EPA’s conclusions are in direct conflict with environmental studies which have documented that the development of frogs is impaired by atrazine. The European Union has classifieds atrazine as a category 1 endocrine disruptor (evidence of disruption in a living organism). A research study by the University of California has found that frogs exposed to atrazine – in concentrations within federal stadards – can become so completely feminized that they can mate and lay viable eggs. In addition to causing severe harm to endangered species, atrazine has been linked to a myriad of health problems in humans including both the congenital disorder gastroschisis and choanal atresia in areas where the chemical is more widely used. Along with atrazine, propazine and simazine, also in the traizine class of chemicals, have also been linked to developmental and reproductive toxicity.
The EPA dismissed the impact of 2,4-D as not relevant although it found a number of thyroid and developmental effects in animals treated with 2,4-D. Scientific studies have determined that a high concentration of 2,4-D in the urine is associated with elevated levels of the luteinizing hormone (LH) – responsible for stimulating the production of testosterone in males and regulating the menstrual cycle and ovulation in females. Other studies have documented abnormal sperm and higher rates of birth defects in farmers with long-time exposure to 2,4-D, as well as effects on the thyroid and gonads.
The International Agency for Research on Cancer (IARC) has classified the popular herbicide, 2,4-D, as a Group 2B, “possibly carcinogenic to humans.” Twenty six experts from 13 countries met at the World Health Organization’s (WHO) IARC in Lyon, France to assess the carcinogenicity of the insecticide lindane, the herbicide 2,4-D, and insecticide DDT. Glyphosate, the ingredient in the popular Roundup weed killer, has been previously classified as a Group 2A “probable” carcinogen, by the IARC based on sufficient evidence of carcinogenicity.
“Exposures to herbicides in early life can lead to disease in childhood or disease later on in adult life or even old age,” said Dr. Landrigan, dean for global health at Mount Sinai School of Medicine. “Herbicide chemicals can also cross from mother to child during pregnancy and prenatal exposures that occur during the nine months of pregnancy are especially dangerous.”
“Physicians are very concerned about exposure to the combination of 2,4-D and glyphosate because of the potential lifelong and irreversible effects on the health of vulnerable populations, including children, pregnant women and farm workers,” said Dr. Thomasson, executive director of Physicians for Social Responsibility. “Policy decisions should take into account the costs that can result from failure to act on the available data on toxic herbicides.”
“2,4-D already is permitted by EPA to remain as residues on over 300 different forms of food,” said John P. Wargo, Ph.D., professor of environmental health and politics at Yale University. “Spraying millions of additional acres with these chemicals will increase their contamination of soils, surface and groundwater and foods bearing their residues. If applied by aircraft, sprays will drift to adjacent lands, potentially endangering those who reside, go to school or work nearby.”
“There is strong evidence that 2,4-D induces oxidative stress, a mechanism that can operate in humans, and moderate evidence that 2,4-D causes immunosuppression, based on in vivo and in vitro studies. However, epidemiological studies did not find strong or consistent increases in risk of NHL or other cancers in relation to 2,4-D exposure.”
In the review conducted by IARC experts, population-based case-control studies of 2,4-D exposure in relation to lymphoma and leukemia were found to provide mixed results. The working group conducted a meta-analysis of 11 studies that shows no association of non-Hodgkin lymphoma with over-exposure to 2,4-D, although the results appeared to be sensitive to whether the studies adjusted for other pesticides. The consensus of the working group was that there is inadequate evidence in humans for the carcinogenicity of 2,4-D, although a substantial minority considered that the evidence was limited. But in animal studies, the group finds that there was limited evidence in experimental animals for the carcinogenicity of 2,4-D, due to methodological concerns regarding the positive studies. Many of the studies under review observed increased incidence of reticulum-cell sarcoma in laboratory mice. In male rats, 2,4-D in the diet induced a positive trend in the incidence of rare brain cancer tumors (astrocytomas). However, other studies provided strong evidence that 2,4-D induces oxidative stress that can operate in humans and moderate evidence that 2,4-D causes immunosuppression, based on in-vivo and in-vitro studies.
2,4-D, one half of chemical makeup of Agent Orange, is highly toxic as it is linked to numerous adverse health effects, including increased risk of birth defects, reduced sperm counts, Parkinson’s disease, and endocrine disruption. Unfortunately, its use is predicted to increase due to the deregulation and expected proliferation of 2,4-D tolerant genetically engineered (GE) crops. Concerns around increased 2,4-D use on GE crops revolves around increasing the onset of 2,4-D-resistant weeds, direct and indirect adverse impacts on human health, increased in drift to non-target sites, and the contamination of food and water. Earlier this year, several conservation, food safety, and public health groups filed a motion challenging the EPA’s decision to expand the use of a new 2,4-D product to be used on GE crops citing serious impacts the powerful new herbicide cocktail will have on farmworkers, neighboring farms, and ground and surface water, as well as endangered species.