ESTIMATING CONCENTRATIONS OF TCE AND PCE DELIVERED TO THE PLAINTIFF’S HOMES IN THE FAMOUS WOBURN TOXIC TRIAL USING LINKED CONTAMINANT TRANSPORT AND WATER DISTRIBUTION MODELS

In the 1986 federal trial described in “A Civil Action”, the plaintiffs’ allege that groundwater contamination from two properties flowed to Woburn, Massachusetts municipal wells G and H and the ingestion of the toxic chemicals caused severe health effects including childhood leukemia. A recent epidemiologic study showed a statistically positive association between gestational exposure to water from wells G and H and the occurrence of childhood leukemia in Woburn. That study used a water distribution model to estimate the contribution of water from wells G and H to residences across the city. The statistical association is based solely on the calculated exposure of water from wells G and H, without consideration of contaminant concentrations.

To provide insight into the possible amounts of TCE and PCE exposure in each plaintiff’s residence between 1964 and 1979, when wells G and H operated, we linked the results of our contaminant transport model to the water distribution model. The water distribution model, which divided the city into 54 hydraulic neighborhoods and accounted for water contributed from six uncontaminated wells in other parts of town, calculated the monthly fraction of water from wells G and H that each hydraulic neighborhood received, which varied spatially and temporally due to management of pumping rates and schedules in all eight city wells. The concentrations of TCE and PCE in wells G and H predicted by the contaminant transport model are multiplied by the fraction of wells G and H water predicted by the water distribution model to estimate the range of concentrations that were likely delivered to the residents in Woburn. From these results, we can extract the range of concentrations delivered to seven of the plaintiffs’ residences from the week of conception to their date of diagnosis. Our results show that exposure varied greatly depending on date of birth and hydraulic neighborhood. We hope these results can be used by epidemiologists and toxiocologists to further explore possible causes of the Woburn childhood leukemia cluster.