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Hazard identification of environmental pollutants by combining results from ecological and biomarker studies: an example
Citation:
SCHREINEMACHERS, D. M. Hazard identification of environmental pollutants by combining results from ecological and biomarker studies: an example. Presented at International Society of Environmental Epidemiology Annual Conference, Pasadena, CA, October 12 - 16, 2008.
Impact/Purpose:
research results
Description:
Objective: Linking exposures from environmental pollutants with adverse health effects is difficult because these exposures are usually low-dose and ill-defined. According to several investigators, a series of multidisciplinary, multilevel studies is needed to address this problem. Ecological studies are a first step in the identification of a public health problem associated with a suspected environmental exposure. Based on their results hypotheses for more targeted studies are created in order to confirm the association. Materials and Methods: Publicly available, national databases were used for the ecological and targeted studies in this example. Spring wheat, grown in Minnesota, Montana, North Dakota, and South Dakota, is treated for at least 85% of its acreage with chlorophenoxy herbicides. Ecological studies investigated rates of birth malformations and mortality from cancer, ischemic heart disease, and diabetes during the 1980’s and 1990’s in rural, agricultural counties of these four states. Wheat acreage per county was used as a surrogate for exposure to chlorophenoxy herbicides. In a subsequent more targeted study based on NHANES III data, recent exposure to the chlorophenoxy herbicide 2,4-D, as indicated by presence in the urine, was investigated in association with changes in lipid profile and glucose metabolism. Results: Results from the ecological studies showed that in counties with a high level of wheat agriculture, levels of adverse effects were increased in comparison to low-wheat counties. Examples of statistically significant increases for cancer mortality among men, age 65 and over, were: pancreas 33%, prostate 23%, larynx 58%. Increased birth malformations for combined boys and girls were observed for circulatory/respiratory (65%) and musculoskeletal/integumental (50%) malformations. Infant death from congenital malformations among boys in high wheat counties was more than double the rate in low-wheat counties. Significantly increased mortality from acute myocardial infarction was observed for ages 25-85+ among men (30%) and women (25%), and from type 2 diabetes for ages 45-85+ among men (24%) and women (17%). Analyses of NHANES III data are ongoing. The results are expected to increase our understanding of the causal path between environmental exposures to chlorophenoxy herbicides and disease. Conclusions: The low resource-intensive methods developed in these studies can be used to link observed increases of many diseases with environmental pollutants. Disclaimer: This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.