Multi-Continental Multimedia Model of Pollutant Intake and Application to Impacts of Global Emissions and Globally Traded Goods.

Abstract

Decision-makers seeking to more comprehensively assess and mitigate the environmental health impacts of products and chemicals require a tool to quantify the impacts associated with global emissions, global supply chains, and global food trade. To be effective, this tool needs to include pollutant fate in multiple environmental media, cover multiple exposure pathways accounting for trade of pollutant through food, and account for high exposure intensity areas and transboundary transport, all while minimizing computational needs. This thesis thus develops IMPACTWorld, the adaptation of a multimedia model to a global scale that accounts for trans-boundary transport and urban exposure. I use IMPACTWorld to calculate the regional intakes of ingestion-dominant polychlorinated biphenyl-118 (PCB-118) and inhalation-dominant fine particulate matter (PM2.5). I then analyze spatial differences in the intake fraction (iF), which is the fractional population intake of each regional emission. PM2.5 iFs are dominated by local urban exposure, whereas transboundary transport of the more persistent PCB-118 leads to substantial portions of the pollutant ingested outside the region of emission. This model helps to further bridge the fields of life cycle assessment and risk assessment by calculating impacts from both the emitter and receiver perspectives. I then add a component to IMPACTWorld that accounts for pollutant economic fate through trade of food and feed. By applying the expanded model to two pollutants that bioconcentrate differently in food and have different global emissions patterns, I find that food exports can substantially alter the absolute pollutant regional intake Finally, IMPACTWorld is combined with an economic model of global trade to yield the first spatially-explicit integrated model describing the full causal chain from consumption to impacts. The results for PM2.5 suggest that the majority of the PM-related health impacts induced by consumption in developed countries occur outside their borders, mainly in Asia. In summary, this thesis reveals new insights into impacts associated with environmental pollutant transport, pollutant transport through food, and “virtual” export of pollution through global trade. It thus provides a motivation and foundation for further exploration of the significance and contribution of these impact mechanisms in the assessment of a product or emission.