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Low-Dose Exposures to Pesticides May Threaten Developing Embryos
(Beyond Pesticides, May 18, 2004) Low-dose exposures to agricultural and lawn care pesticides may cause injury to developing embryos before a pregnancy is even noticed, according to a study conducted by researchers at Marshfield Clinic Research Foundation (MCRF), Marshfield, Wis., and being published in the May 2004 issue of Environmental Health Perspectives, the journal of the National Institute of Environmental Health Sciences, National Institutes of Health.

"In research conducted with mouse embryos, injury was observed during laboratory studies with a variety of agrochemicals and lawn care products, such as weed and insect killers and fertilizers, at concentrations previously assumed to be without adverse health consequences for humans," said Anne Greenlee, Ph.D., lead author of the article.

Types of injury observed included slowed embryonic development and reductions in the number of cells comprising the embryo, both of which may contribute to implantation failures and lengthening in time needed to achieve pregnancy.

Since it is impossible to define precisely the amount of chemical(s) dangerous to an individual's reproductive health, a cautious approach seems best, Greenlee said.

Greenlee, a scientist in Marshfield Clinic Research Foundation's National Farm Medicine Center (NFMC), said her lab conducted the study because little is known about residential use of pesticides and their possible effects on embryonic development in the first few days of pregnancy. Her study used mouse embryos to model possible human effects as embryos of different animal species react similarly at this early stage of development.

Greenlee stressed the importance of additional work needed to validate these findings for purposes of human risk assessment and to determine relevance of lab results to pregnancy outcomes.

In this study, researchers examined 13 agrochemicals and lawn care herbicides (weed killers) for their effects on embryo development during the preimplantation period. The preimplantation period corresponds to the first to seventh day of pregnancy, when an embryo is rapidly dividing and before implantation occurs in the mother.
The study, funded by the Wisconsin Department of Agriculture, Trade and Consumer Protection (DATCP) and MCRF disease-specific research funds, examined active ingredients in commercial pesticide formulations. Agricultural chemicals studied are typical of those used in the upper Midwest. Lawn pesticides studied are typical of those used throughout the United States.

Active ingredients tested included six herbicides (atrazine, dicamba, metolachlor, 2,4-D, pendimethalin, MCPP); three insecticides (chlorpyrifos, terbufos, permethrin); two fungicides (chlorothalonil, mancozeb); one drying agent (diquat) and one fertilizer (ammonium nitrate).

Greenlee's manuscript, "Low-dose Agrochemicals and Lawn Care Pesticides Induce Developmental Toxicity in Murine Preimplantation Embryos," is published online at http://ehp.niehs.nih.gov/docs/2004/6774/abstract.html. Additional authors are Tammy Ellis, NFMC; and MCRF Biostatistician Dick Berg, M.S.

Research published by Greenlee in the July 2003 issue of the journal Epidemiology showed that women who mix and apply pesticides or apply fungicides in the two-year period before trying to conceive significantly increase their chances of infertility. In that study, it was shown that infertile women were 27 times more likely to have mixed and applied pesticides than women who had become pregnant.

The Marshfield Clinic system consists of 40 patient care and research and education facilities in Northern, Central, Eastern and Western Wisconsin, making it one of the largest comprehensive medical systems in the United States.

TAKE ACTION: Take a precautionary approach to avoid low-dose exposures to pesticides. Exposure to lawn care chemicals can be avoided by creating a healthy, pest-resistant lawn. Find out how here. Get rid of other pests without hazardous pesticides by going to Beyond Pesticides’ Alternatives Fact Sheets.