Integrating site-specific dispersion modeling into life cycle assessment, with a focus on inhalation risks in...

It has become increasingly important for environmental managers to evaluate the human health (HH) impact of chemicals in their supply chain. Current life cycle assessment (LCA) methods are limited because they often only address the HH impact at large geographical scales. This paper aims to develop a method that derives a regionalized life cycle inventory data set and site-specific air dispersion modeling to evaluate the HH impact of chemicals along the life cycle phases at finer geographical scales to improve decision-making, with focus on inhalation pathway. More specifically, cancer risk and noncancer hazard index (HI) are quantified at the county level to identify high-risk regions and at the census tract level to reveal the geographical pattern of health impacts. The results showed that along the cradle-to-gate life cycle stages of a widely used chemical, methylene diphenyl diisocyanate (MDI), the accumulative inhalation risk was 3 orders of magnitude below the U.S. Environmental Protection Agency (EPA) risk management thresholds for both cancer risk (2.16 × 10^-9) and noncancer HI (1.53 × 10^-3). However, the absolute value of inhalation risks caused by the case study chemicals varied significantly in different geographical areas, up to 4 orders of magnitude. This paper demonstrates a feasible approach to improve human health impact assessment (HHIA) by combining site-specific air dispersion modeling and LCA using publicly available inventory data. This proposed method complements existing life cycle impact assessment (LCIA) models to improve HHIA by employing both HH risk assessment and LCA techniques. One potential outcome is to prioritize pollution prevention and risk reduction measures based on the risk maps derived from this method. Implications: It has become increasingly important for environmental managers to evaluate the human health impacts of chemicals in their supply chain. Regionalized life cycle inventory data sets should be developed using publically available databases such as EPA's toxic release inventory. The combination of site-specific dispersion modeling and life cycle assessment modeling can improve human health impact assessment of chemicals by providing more regionalized results along their supply chain.