A model for assessing and managing the risks of environmental lead emissions

In response to recent activity and legislation concerning lead and its role in electric vehicle development, a model has been developed to assess the health risks to residents from environmental lead emissions. This model may be used to predict the risks to residents in the vicinity of facilities discharging lead into the air. This model is also important for risk management, allowing for risk-based regulations regarding limits on lead emissions. The model is comprehensive, linking together a source term, air dispersion model, household exposure model, physiologically-based pharmakokinetic blood-lead model, and a determination of reference dose. Parameters are treated as distributions, and are considered either uncertain or variable. A range of physiological and behavioral parameters are used to distinguish between various age and gender groups, to reflect the variability in risk of adverse effect to these subsets of the exposed population. A sensitivity study is performed, including a case considering the uncertainty in reference dose which is compared to the case of a deterministic reference dose. Different types of variability are investigated, the variability across sensitive sub-populations of age and gender, and the individual variability within these populations. We found that the differentiation between uncertainty and variability in predicting non-cancer risk human health risk was important, and that methods that combined uncertainty and variability were not expected to be protective to sensitive individuals within a sub-population.