The Sixteenth Conference of the International Society for Environmental Epidemiology (ISEE): Abstracts
Associations between adverse health effects and environmental exposures are difficult to study, because exposures may be widespread, low-dose in nature, and common throughout the study population. Therefore, individual risk-factor epidemiology may not be the right tool. A better method may be provided by a series of multidisciplinary studies, starting with a hazard identification study, such as an interregion comparison or population study. Existing databases routinely collected by Federal Agencies can be used for the purpose of hazard identification. Previous population studies showed that cancer mortality and birth malformations in rural, agricultural counties of Minnesota, Montana, North Dakota, and South Dakota were associated with wheat acreage per county, a surrogate measure for chlorophenoxy herbicide exposure. Chlorophenoxy herbicides are the predominant herbicides applied to spring and durum wheat in these four states. Environmental factors have been implicated in the current increase of diabetes. There is evidence of an association between diabetes type 2 and exposure to Agent Orange, which contains chlorophenoxy herbicides and the contaminant dioxin. Dioxin may or may not be present as a contaminant in current commercial preparations of chlorophenoxy herbicides. The current study investigates if an association exists between mortality from diabetes mellitus and related diseases (ischemic heart disease, cerebrovascular disease, renal disease) and wheat acreage per county, a surrogate for chlorophenoxy herbicide exposure, in rural, agricultural counties of the same states.
Information on mortality during 1979-1988 (underlying and multiple cause), and during 1989-1998 (underlying cause) was obtained from the NCHS mortality database. Agricultural information was obtained from the USDA website.
Counties were distributed into a low- and a high-wheat group, based on the percentage of a county’s land area devoted to wheat acreage. Preliminary analyses showed increased rates of diabetes mortality (underlying cause of death) among subjects age 45 and over, comparing high-wheat to low-wheat counties: the increases for men and women were respectively 15 and 4% during 1979-1988, and respectively 36 and 28% during 1989-1998.
Chlorophenoxy herbicides are one of the most widely used herbicides in the U.S. Although the sole purpose of this study is hazard identification, results will be relevant, since they may indicate directions for further investigation.
This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.