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BIRTH DEFECTS IN FOUR U.S. WHEAT-PRODUCING STATES
Citation:
Schreinemachers, D M. BIRTH DEFECTS IN FOUR U.S. WHEAT-PRODUCING STATES. Presented at 14th Conference of the Intl Society for Environmental Epidemiology, Vancouver, BC, Canada, August 11-15, 2002.
Description:
Birth Defects in Four U.S. Wheat - Producing States
Dina M. Schreinemachers, National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711
Wheat agriculture in Minnesota, Montana, North Dakota, and South Dakota relies heavily on chlorophenoxy herbicides for control of broadleaf weeds. Results from a previous study showed increased mortality for several cancer sites in rural counties in these four states with a high wheat acreage. The current ecologic study investigates whether an association exists between birth defects rates and wheat acreage in those same counties. Perinatal information by county was obtained for 1995 through 1997 births from linked birth / infant death files from the National Center for Health Statistics. Agricultural information by county was obtained from the U.S.Department of Agriculture web site. Agricultural counties with a mostly rural population were selected, and subdivided into a low-wheat and a high-wheat group based on the percentage land dedicated to wheat agriculture with respect to the median of all agricultural counties. In addition, a group of urban counties with a low level of agriculture was selected. Rates of birth defects were compared between urban and agricultural counties, and between high-wheat and low-wheat counties. Logistic regression was used for the analyses, and odds ratios with 95% confidence intervals were obtained for the comparison of categories of congenital anomalies for combined male and female births with adjustment for covariates. Odds ratios comparing agricultural counties to urban counties were as follows: births with any anomaly 1.95 (1.73-2.19); central nervous system 1.68 (1.12-2.54); circulatory / respiratory 2.12 (1.54-2.93); gastrointestinal 1.12 (0.75-1.67); urogenital 2.73 (2.04-3.64); musculoskeletal / integumental 1.94 (1.58-2.40); chromosomal 2.37 (1.63-3.45); other anomalies 1.67 (1.36-2.05). Odds ratios comparing high-wheat to low-wheat counties were: births with any anomaly 1.16 (0.99-1.36); central nervous system 0.77 (0.41-1.45); circulatory / respiratory 1.85 (1.21-2.84); urogenital 1.17 (0.83-1.66); musculoskeletal / integumental 1.46 (1.12-1.89); chromosomal 0.90 (0.53-1.54); other anomalies 0.72 (0.51-1.00). Births conceived during the months of herbicide application (April, May, or June) were at an additional risk for circulatory / respiratory anomalies in comparison to births conceived during other months of the year (OR 1.56, 95% CI 1.01-2.39). These results indicate that rates of birth defects are increased in agricultural counties of Minnesota, Montana, North Dakota, and South Dakota, in comparison to urban counties. In addition, in counties where wheat is one of the main crops and environmental exposure to chlorophenoxy herbicides and/or their contaminants is likely, rates of circulatory /respiratory and musculoskeletal / integumental anomalies are increased. This information is highly relevant considering the widespread use of these herbicides in the U.S. for weed control in the maintenance of home lawns, road sides, parks, golf courses, national forests, and rangeland. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.