Academic journal article Environmental Health Perspectives

The University of Michigan Dioxin Exposure Study: Population Survey Results and Serum Concentrations for Polychlorinated Dioxins, Furans, and Biphenyls

Academic journal article Environmental Health Perspectives

The University of Michigan Dioxin Exposure Study: Population Survey Results and Serum Concentrations for Polychlorinated Dioxins, Furans, and Biphenyls

Article excerpt

BACKGROUND: The University of Michigan Dioxin Exposure Study was undertaken to address concerns that the discharge of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) from the Dow Chemical Company in the Midland, Michigan, area had resulted in contamination of soils in the Tittabawassee River floodplain and the city of Midland, leading to an increase in residents' body burdens of these compounds.

OBJECTIVE: In this article we present descriptive statistics from the resident survey and sampling of human serum, household dust, and soil and compare them with other published values.

METHODS: From a multistage random sample of populations in four areas of Midland and Saginaw counties and from a distant referent population, we interviewed 946 adults, who also donated blood for analysis of PCDDs, PCDFs, and polychlorinated biphenyls (PCBs). Samples of household dust and house perimeter soil were collected from consenting subjects who owned their property.

RESULTS: All five study populations were comparable in age, race, sex, and length of residence in their current home. Regional differences existed in employment history, personal contact with contaminated soils, and consumption of fish and game from contaminated areas. Median soil concentrations were significantly increased around homes in the Tittabawassee River floodplain (11.4 ppt) and within the city of Midland (58.2 ppt) compared with the referent population (3.6 ppt). Median serum toxic equivalencies were significantly increased in people who lived in the floodplain (23.2 ppt) compared with the referent population (18.5 ppt).

CONCLUSIONS: Differences in serum dioxin concentrations among the populations were small but statistically significant. Regression modeling is needed to identify whether the serum concentrations of PCDDs, PCDFs, and PCBs are associated with contaminated soils, household dust, and other factors.

KEYWORDS: biomonitoring, dioxins, dust, environmental exposure, furans, polychlorinated biphenyls, serum, soil, survey. Environ Health Perspect 117:811-817 (2009). doi:10.1289/ehp.11780 available via http://dx.doi.org/ [Online 22 December 2008]

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The University of Michigan Dioxin Exposure Study (UMDES) was undertaken in response to concerns from residents that the discharge of dioxin-like compounds (DLCs) from the Dow Chemical Company facilities in Midland, Michigan, resulted in contamination of soils in the Tittabawassee River floodplain and in the city of Midland, leading to an increase in residents' body burdens of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs).

PCDDs, PCDFs, and polychlorinated biphenyls (PCBs) are ubiquitous in soils, sediments, air, and animal tissues in industrialized nations [Alcock and Jones 1996; U.S. Environmental Protection Agency (EPA) 2003]. They are often the unintentional byproducts of burning and waste incineration, primary and secondary metal smelting, and chlorine-based chemical processes (U.S. EPA 2006). Within the lower peninsula of Michigan, background soil concentrations of the 17 PCDDs and PCDFs recognized by the World Health Organization (WHO) as having dioxin-like activity (Van den Berg et al. 1998) range from 0.4 to 34.7 ppt toxic equivalency (TEQDF-1998, where D is PCDDs, F is PCDFs, and 1998 indicates the WHO 1998 toxic equivalency factors, respectively), with a median level of 4.6 ppt TEQDF-1998 [Michigan Department of Environmental Quality (MDEQ) 1999]. In contrast, soils and sediments sampled from along the Tittabawassee River, downstream of the Dow Chemical Company, ranged from 4 to 1,980 ppt TEQDF-1998 (Hilscherova et al. 2003). Previous sampling of the top 1 in. of soils from along the Tittabawassee River (Demond et al. 2008) ranged from 1.1 to 9,351 ppt TEQDFP-1998 (or from 1.1 to 7,258 ppt TEQDFP-2005; where D is PCDDs, F is PCDFs, P is PCBs, and 1998 or 2005 indicates the WHO 1998 or 2005 toxic equivalency factors, respectively). …

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