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IMPROVING EXPOSURE ASSESSMENT IN DISINFECTION BYPRODUCTS (DBP) EPIDEMIOLOGIC STUDIES
Impact/Purpose:
This cooperative agreement is designed to conduct a series of epidemiologic analyses to estimate the strength of the associations between several disinfection by-products (DBPs) in drinking water and a range of parameters of reproductive function. Future revisions of the DBP Stage 2 rule may use epidemiology studies to assist in determining the magnitude of the risk from disinfected drinking water. Improved exposure assessment is essential to proper evaluation and interepretation of epidemiological findings of associations of DBP exposure and adverse health effects. Greater confidence in the basis for these correlations will facilitate development of risk assessments and regulatory descisions for DBPs.
Description:
In 1997, an EPA expert panel was convened to evaluate epidemiologic studies of adverse reproductive or developmental outcomes that may be associated with drinking water DBPs. The panel recommended that further efforts be made in an existing cohort study, headed by Dr. Waller and Dr. Shanna Swan, to evaluate personal exposures to various DBPs in relation to reproductive outcomes. Initial analyses of data from this cohort had demonstrated an association between spontaneous abortion and drinking water DBP exposure, specifically with bromodichloromethane. Supplementation and further analyses of the cohort data was recommended. Replication of the study in another geographic area was also recommended.There are four research objectives for this project: 1.) To further characterize exposure to individual trihalomethanes (THMs) in the California Pregnancy Outcome Study (POS); 2.) To use distribution system modeling to estimate THM levels at or near homes of a subsample of POS subjects; 3.) To examine the association between THMs and several male and female reproductive endpoints in the California Reproductive Health Study; and 4.) To conduct a new prospective pregnancy study of pregnancy outcomes and DBP exposure in collaboration with Kaiser Permanente in San Francisco, California.