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Final Progress Reports: University of California-Davis: Epidemiology Studies

Superfund Research Program

Epidemiology Studies

Project Leader: Ellen B. Gold
Grant Number: P42ES004699
Funding Period: 2000-2010

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Final Progress Reports

Year:   2009  2004 

This project provides epidemiologic evaluation of human health effects associated with exposure to environmental contaminants in residents adjacent to a Superfund site in Sacramento, California. The researchers accomplish this by evaluating physiologic dysfunction, specifically reproductive and other hormone-related health effects, in female adults (aged 20-50 years during the likely exposure period of 1988-96) residing downwind or in the groundwater plume of the Sacramento Superfund site and comparing the rates of these health effects to a non-exposed but similar population nearby and relating these rates to likelihood of exposure. In addition to interviewing women residing in these areas and in a comparison area, they are using serum and urine biomarkers of exposure and of health effects that have been developed here.

This project identified over 5260 households, screened over 1460 women in the three study areas for eligibility in the study, interviewed 814 women and obtained blood from the first 450 eligible women and daily urine samples for two menstrual cycles from 274 women who were still menstruating in the three areas. Researchers suspended blood collection a few years ago, having found no significant differences in serum parameters they were measuring among the three study sites. Researchers also suspended enrollment and data collection two years ago due to inadequate funds. The three study areas appear comparable on a number of socioeconomic indicators, as well as on general community and women's health concerns (none of the top 4 of which include the Superfund site or endocrine/reproductive concerns, respectively).

Further, researchers have observed no notable differences in thyroid hormone levels among the first 450 women examined among the three study areas, as expected, since the relevant exposure that might have affected thyroid function ended in 1996, and no prolonged adverse effect on the thyroid would be expected. Researchers have detected no evidence of environmental estrogens in any of the first 250 urine samples tested and thus suspended this testing several years ago as well. Largely, no notable differences were seen in reproductive health or endocrine effects, but further analyses with additional data are required from this ongoing project to determine any differences in health effects that might have occurred during the times of likely exposure.

Finally, researchers have established several collaborations. First, they are collaborating with the Fate and Transport Project in assessing likelihood (realizations) of exposure in each of the households using GIS techniques and analyzing the findings in relation to outcomes ascertained in our interviews, which should result in a publication in the next year or so. Second, researchers have been collaborating with the Reproductive Biomarkers Project, in having laboratory assays of the urine samples conducted to assess ovarian function, which they will examine in relation to study area and likelihood of exposure, which should result in a publication in the next year or so. Third, researchers have collaborated with CDC, which provided funds for us to have them assay our urine samples for perchlorate, iodide, nitrate and thiocyanate, and they are using those values to assess the relation of those assay results to the endocrine and reproductive outcomes of interest, which should result in a publication or two in the next year or so. The analyses thus far indicate no differences in urinary perchlorate concentrations or computed perchlorate dose among the three study sites or a relation of current perchlorate dose to current thyroid function or thyroid illness. Fourth, junior faculty have become involved and will analyze the data in relation to fast food consumption, the built environment and opportunities for physical activity, lifetime physical activity and investigating the relation of thyroid hormones to premenstrual and menopausal symptoms. These analyses should result in several publications in the next year or two.

Applications of epidemiologic techniques in this project have not only facilitated applications of the biomarkers in humans in the exposed population and assessment of the relation of exposure to environmental contaminants to human health effects, but will also help to elucidate modification of these effects by host and lifestyle factors. In turn, this project has contributed to the other projects by providing epidemiologic expertise for developing further field applications of techniques developed in the UCD laboratories in the future. In this effort, this project has interacted with the cores mentioned above to evaluate exposures to endocrine disruptors as a result of residing downwind or in the groundwater plume of a Superfund site, to assess the likely routes of exposure, and to assess the relation of such exposures to adverse reproductive and other endocrine health effects.

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