Superfund Research Program
Early Life Exposure to Tetrachloroethylene (PCE)-Contaminated Drinking Water and Social Stressors may Interact to Increase the Risk of Substance Use Later in Life
Dr. Ann Aschengrau’s group is conducting a population-based retrospective cohort study to test the hypothesis that tetrachloroethylene (PCE) found in the public drinking water supplies in Cape Cod, Massachusetts is associated with an increased risk of nervous system abnormalities among men and women exposed during gestation and childhood. The source of the water contamination was a vinyl liner that was applied to hundreds of miles of asbestos cement water distribution pipes in eight towns in the Cape Cod area from the late 1960s through 1980. The study population is composed of individuals who were exposed to PCE contaminated drinking water during 1969-1983 and a comparable group of unexposed subjects. Exposed subjects include individuals with both prenatal and childhood exposure and their older siblings with only childhood exposure. Hypothesized effects include an increased prevalence of indicators and diagnoses related to vision disorders and developmental disabilities of learning and attention; impaired performance on neuropsychological and vision tests; and increased prevalence of cerebral pathology and dysfunction as seen in neuroimaging studies. Nervous system effects are anticipated to be time-dependent with greater effects among individuals who have both prenatal and childhood exposure compared with those with only childhood exposure.
Over the past year, Dr. Aschengrau and her team have made progress in the areas of tracing the study population; collecting, computerizing and cleaning questionnaire data; conducting a pilot study and finalizing preparations for the clinical data collection (e.g., neuroimaging); geocoding addresses; conducting an exposure validation study; conducting epidemiological and statistical analyses; and drafting manuscripts for publication.
To date, the researchers have identified 4,392 eligible subjects, and successfully traced approximately 94%. A self-administered questionnaire was sent to all living subjects in order to gather information on indicators and diagnoses of learning, attention, and vision disorders, confounding and effect modifying variables, and residential histories. To date, responses have been received from approximately 33%. A final mailing to non-responders is currently underway. The questionnaires have also been screened to identify subjects who are appropriate for follow-up neuropsychological and vision testing and neuroimaging studies. These activities will begin in January 2008.
Project researchers have also used EPANET, an EPA software package, to model the complex interconnected geometries of each town’s entire water distribution system, and hence assess more accurately a subject’s exposure to PCE. In addition, an exposure validation study has been completed that compares the EPANET assessments with historical records of PCE concentrations in drinking water samples. The study shows that there is a very good level of correlation between the measured and estimated PCE levels.
Dr. Aschengrau and her team have also completed epidemiological analyses and manuscripts that examine the relationship between (EPANET-assessed) PCE exposure and low birth weight, prematurity, intrauterine growth retardation, learning disabilities, spontaneous abortion, and breast cancer. A statistical methods paper has also been drafted to illustrate the failure of commonly held assumptions in generalized estimating equations (GEE) analyses. In addition, a manuscript has been prepared describing the results of the validation study. Lastly, the team and their collaborators have written manuscripts using data from their prior SBRP-funded research to describe: (1) spatio-temporal characteristics of breast cancer on Cape Cod, and (2) groundwater contamination in relation to breast cancer risk. The team expects to publish these manuscripts over the coming year.