of National Affairs, Daily Environment Report (ISSN 1521-9402) 4/27/10The Environmental Protection Agency is studying the herbicide atrazine in
the light of recent studies showing toxic effects on reproductive, immune, and other systems
of laboratory animals, agency officials told an advisory panel April 26.It is time “to take a look at the new science” to determine whether stricter regulation of atrazine is warranted, said Steven Bradbury, acting director of EPA’s Office of Pesticide Programs (OPP).
Bradbury made his remarks to the Federal Insecticide, Fungicide, and Rodenticide Act Scientific
Advisory Panel as the panel began its review of new and old studies of the chemical.
In a background paper presented to the advisory panel April 26, EPA said that in recent years, numerous toxicological and epidemiologic studies have become available evaluating the toxicity profile or mode of action of atrazine.
The agency cited studies such as “Gestational Exposure to Atrazine: Effects on the Postnatal Development of Male Offspring,” published in the Journal of Andrology in 2008, and “Atrazine-Induced Alterations in Rat Erythrocyte Membranes: Ameliorating Effect of Vitamin E,” published in Molecular Toxicology, also in 2008.
EPA Re-evaluating Atrazine As a result of this new information, OPP, EPA’s Office of Research and Development, and the Office of Water are re-evaluating atrazine and its metabolites deethyl-atrazine (DEA), deisopropyl-atrazine (DIA), and diamino-s-chlorotriazine (DACT), the agency said in the background paper, Re-Evaluation of Human Health Effects of Atrazine: Review of Experimental Animal and in vitro Studies and Drinking Water Monitoring Frequency.
EPA announced the re-evaluation effort Oct. 7 (193 DEN A-7, 10/8/09).
The panel of science advisers on April 26 began a week-long process of reviewing studies used to support the 2003 reregistration eligibility decision on atrazine and new studies available up to Jan. 30, 2010.
EPA is soliciting comment from the advisory panel on the toxicological importance and human relevance of findings on the effects of atrazine on the hypothalamic-pituitary-adrenal axis, immune system, prostate, brain, and the enzyme known as aromatase.
Complex Interactions
The toxic effects seen after atrazine exposure are the result of multilevel interactions of a variety of systems, such as the neuroendocrine, reproductive, nervous, and immune systems, Elizabeth Mendez, senior scientist in the OPP’s Health Effects Division, said at the meeting. The body’s response to exposure from chemicals such as atrazine may vary through various stages of life, she added.
“There may be some effect of atrazine on the pituitary gland,” Ralph Cooper, a scientist in the EPA’s National Health and Environmental Effects Research Laboratory, said in his presentation to the panel. The pituitary gland controls the functions of the other endocrine glands.
EPA Working on Assessments
EPA said it is still in the problem-formulation stage on hazard and exposure assessments for atrazine. Problem formulation involves considering the available information regarding pesticide use, toxicological effects of concern, and exposure pathways and duration of exposure along with key gaps in data or scientific information, it said.
Atrazine is one of the most widely used agricultural herbicides in the United States, with approximately 70 million pounds of active ingredient applied per year, primarily on corn crops, according to the EPA paper. As a condition for declaring atrazine eligible for reregisteration in 2003, EPA required the registrant, Syngenta Crop Protection, to monitor drinking water in certain areas, generally the corn and sorghum growing area of the Midwest (217 DEN A-5, 11/10/03).
EPA said in its paper that in addition to the potential risks to human immune and other systems, the agency seeks feedback from the advisory panel on whether to require more frequent drinking water monitoring. It currently requires Syngenta to sample drinking water weekly during the growing season and biweekly for the remainder of the year.
“It is prudent for the agency to evaluate the hazard potential of atrazine and the drinking water monitoring strategy together,” the agency said.
