Contaminant Transport Through Initially Dry Soil

We combined dose-response analyses with a probabilistic exposure assessment to estimate the risks to native Canadians who ingest methylmercury via fish consumption from natural lakes and a reservoir in British Columbia. Available dose-response data included multivariate measurements of central nervous system functioning in Iraqi children exposed to methylmercury prenatally. We applied the method of principal components to simplify the data structure. The first principal component described close to 80% of the variability in the data, making it a reasonable choice as an index. The relationship between mercury in maternal hair and the probability of an abnormal neurological effects index was modeled with the logistic and Weibull functions. The goodness-of-fit of the two models is discussed and the results compared to other published dose-response analyses. Exposure distributions were developed to represent methylmercury dose by using observed data on methylmercury contamination in the lakes and reservoir and reasonable assumptions about other key parameters such as fish consumption. We estimated risks to the target population using Monte Carlo simulation. Consumption of reasonable quantities of fish from these bodies of water does not pose a significant risk to the aboriginal population.