(55o) Quantitative Consequence Analysis on Human Health Due to Accidental Toxic Release Using a Framework of Life Cycle Impact Assessment

A massive accident in chemical plants and storage tanks such as explosions, fires and toxic releases can have significant impacts on employees, facilities, the environment, and nearby people. Generally, a quantitative risk assessment (QRA) is conducted to prevent and mitigate losses from accidents, which is a conventional method to understand, control and reduce individual and societal risk. In terms of toxic chemicals, consequence analysis in QRA mainly focuses on the impact of acute toxicity on humans and calculates the fatality rate by using probit functions or referencing concentration standards such as Acute Exposure Guideline Level. Although the consequence analysis takes into account the short-term impacts caused by the accident, it does not analyze the medium to long-term exposure to hazardous chemicals at non-acute toxic levels on humans and the environment.

The framework of life cycle impact assessment (LCIA) and its index, which is a method of life cycle assessment, can analyze and evaluate potential impacts on humans and the environment such as greenhouse emissions and resource uses throughout product life cycle and business operations. The life cycle impact assessment method based on endpoint modeling (LIME), which is one of LCIA methodologies, can analyze the potential impacts on human health. The framework of LIME consists of four steps: fate analysis, exposure analysis, effect analysis, and damage analysis. These analyses allow for quantitative calculation of potential impacts on human health using Disability-Adjusted Life Years (DALY). DALY is a comprehensive index that represents the disease burden considering not only premature deaths due to diseases or disabilities but also the loss of healthy life years. It becomes possible to analyze potential impacts on delayed human health by integrating the framework of LIME into consequence analysis in QRA for toxic release risks.

The purpose of this study was to conduct a quantitative consequence analysis of the potential impacts on human health by using DALY. First, an event tree analysis was carried out to identify accidental scenarios of a liquified ammonia storage tank. Subsequently, we conducted fate analysis using atmospheric dispersion simulations based on these identified scenarios. Then, we conducted exposure analysis to calculate the increase in the exposure-dose due from the dispersed ammonia. Additionally, we conducted effect analysis to calculate the increase in human health effects based on the results of exposure analysis. Finally, a damage analysis was carried out to calculate the quantitative potential impacts on human health by aggregating each effect such as disabilities and fatalities. This study can contribute to the development of a method for delayed consequence analysis in QRA.