Academic journal article Environmental Health Perspectives

Developmental Toxicity of a Commercial Herbicide Mixture in Mice: I. Effects on Embryo Implantation and Litter Size. (Articles)

Academic journal article Environmental Health Perspectives

Developmental Toxicity of a Commercial Herbicide Mixture in Mice: I. Effects on Embryo Implantation and Litter Size. (Articles)

Article excerpt

We investigated the developmental toxicity in mice of a common commercial formulation of herbicide containing a mixture of 2,4-dichlorophenoxyacetic acid (2,4-D), mecoprop, dicamba, and inactive ingredients. Pregnant mice were exposed to one of four different doses of the herbicide mixture diluted in their drinking water, either during preimplantation and organogenesis or only during organogenesis. Litter size, birth weight, and crown-rump length were determined at birth, and pups were allowed to lactate and grow without additional herbicide exposure so that they could be subjected to additional immune, endocrine, and behavioral, studies, the results of which will be reported in a separate article. At weaning dams were sacrificed, and the number of implantation sites was determined. The data, although apparently by season, showed an inverted or U-shaped dose-response pattern for reduced fitter size, with the low end of the dose range producting 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. Fetotoxicity, as evidenced by a decrease in weight and crown-rump length of the newborn pups or embryo resorption, was not significantly different in the herbicide-treated litters. Key words: 2,4-D, developmental toxicity, dicamba, embryo implantation, fetal loss, herbicide mixtures, mecoprop. Environ Health Perspect 110:1081-1085 (2002). [Online 17 September 2002] http://ehpnet1.niehs.nih.gov/docs/2002/110p1081-1085cavierse/abstract.html

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Although they are not conclusive, a number of epidemiologic studies have linked pesticide exposure to reproductive and developmental toxicity in humans. Pastore et al. (1997) showed a clear positive association between occupational exposure to pesticides, especially during early pregnancy, and the risk of stillbirths in California, and Kristensen et al. (1997), associated central nervous system and limb defects with parental use of pesticide spraying equipment in Norway. In contrast, a case-control study in Holland determined little effect of pesticide exposure on the incidence of central nervous system defects in children of mothers involved in agricultural activities (Blatter et al. 1996); environmental pollution with pesticides, regardless of the occupation of the mother, could have explained the increased risk of spina bifida found in this study. Similarly, Shaw et al. (1999) did not find a clear pattern of association between specific pesticide exposures and risk for birth defects.

More recently, Bell et al. (2001) conducted a case-control study in California, where they linked a statewide database of restricted pesticide applications to residence of the mother to estimate daily pesticide exposure status. The data showed that risk of fetal death from congenital anomalies was increased with maternal pesticide exposure occurring during weeks 3-8 of pregnancy. Additionally, they showed that the odds ratio for pesticide exposure causing fetal death increased when the exposure occurred within the same square mile of maternal residence.

Wives of Dutch fruit growers exposed to pesticides showed an increase in time to pregnancy, defined as the number of noncontraceptive menstrual cycles or months required for a couple to conceive, although no specific pesticide or group of pesticides could be singled out as responsible for the effect (de Cock et al. 1994). Time to pregnancy was also used by Curtis et al. (1999), but they did not find a consistent pattern of association between pesticide exposure and time to pregnancy among Canadian farm couples. However, Curtis et al. did show that some specific pesticides such as organophosphate insecticides and phenoxyacid herbicides were associated with a decrease in fecundity when women engaged in pesticide-related activities. …

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