Daily News Archive

New Study Links Trace Amounts of Top Selling Weed Killer and Miscarriages
(from September 18, 2002)

The Environmental Working Group reports, a new peer-reviewed animal study suggests a surprising link between trace amounts of the nation's top home and lawn herbicide compounds and miscarriages in humans. Researchers at the University of Wisconsin tested the combination of ingredients as they are purchased by consumers off store shelves and at levels far below those at which the government requires the companies to safety test their products.

Herbicides containing 2,4-D, mecoprop and dicamba are currently used in more than 1,500 different commercial formulations, including those that are commonly used at home. Therefore, these researchers believed there was an urgent need to explore in detail the potential reproductive and developmental toxicity of these products. No reports on the reproductive or developmental toxicity of mecoprop or dicamba have been published in the recent literature. However, earlier studies have assessed the teratogenic potential of individual compounds at high doses; these are the only doses we now consider to be toxicologically relevant. Researchers at the University of Wisconsin modified a U.S. Environmental Protection Agency (EPA) Segment II developmental toxicity study (U.S. EPA 2000) protocol to include a low, environmentally relevant dose to test whether in utero exposure to a herbicide mixture containing the phenoxyacid derivatives 2,4-D and mecoprop, the benzoic acid derivative dicamba, and other inactive ingredients leads to developmental toxicity and/or developmental immune and endocrine defects in juvenile mice.

The data, although apparently influenced by season, showed the low end of the dose range producing the greatest decrease in the number of live pups born. The decrease in litter size was associated with a decrease in the number of implantation sites, but only at very low and low environmentally relevant doses.

Among other findings, a higher than normal frequency of human births with central nervous system, urogenital, circulatory/respiratory, or musculoskeletal anomalies in western Minnesota has been linked to the use of 2,4-D and other phenoxy-acetic acid-derived herbicides. Despite these links, 2,4-D and dicamba have previously been reported as not producing reproductive toxicity. However, the epidemiologic evidence just discussed and the results presented here imply that further studies are necessary to determine the safety of these herbicides.

Click here to view this report in full. http://www.ewg.org/pdf/porter_study.pdf