Breast Cancer & the Environment: Using a Novel Surrogate to Investigate Risk

Abstract

Establishing dose-response between environmental contaminants and long latency diseases has proven elusive as the opportunity to measure relevant contamination has evaporated with time. This necessitates using surrogates to evaluate relationships between past environmental exposures and cancer. Generally, epidemiologists evaluate existing exposures directly or use surrogate or contemporaneous records of past exposure. But without measures of past environmental exposures, establishing causation of environmental diseases has been wanting. This study illustrates tools and knowledge available to environmental lawyers, who are primarily concerned with investigating sources of environmental releases and familiar with materials documenting the extent and magnitude of a past release which are generally unknown to the medical epidemiologist. Using these data highlights the contribution lawyers can make to the health field, and suggests collaboration among environmental, legal and health practices. I postulate that exposures to drinking water contaminated by chemicals leaching off hazardous wastes sites is associated with breast cancer. In a previous study the proportion of contaminated surface area of a water district, as delineated by governmental agencies via Hazardous Waste Site status, was validated as a reliable marker of past environmental exposures. The current ecologic study examined the relationship between exposures to the four most prevalent contaminants in Nassau County, New York, and breast cancer between 1991 and 1995 using the novel exposure surrogate. This study demonstrated a dose-response relationship between drinking water exposures during the 1970s and 1980s to Perchloroethylene, (PCE) Trichloroethylene (TCE) and Dichloroethylene, (DCE) and breast cancer in Nassau County. A causal relationship appeared for Trichloroethane (TCA) which was not associated with drinking water. Each per square mile in a water district contaminated with PCE, TCE and DCE carried an increased risk of breast cancer of 14%, 12% and 8%, averaging 4, 4.4 and 4 acres per square mile, respectively.