A Risk Assessment Framework for Evaluating Health Risks from New and Emerging Waste Management Technologies

Until recently, landfills and waste-to-energy (WTE) facilities were the two basic technologies available to process residual (post-recycled) municipal solid waste. These technologies have both advantages and drawbacks, and their relative merits have been debated many different ways. Risk assessments of both technologies have been used to examine their potential threats to human health and the environment, and have found both landfills and WTE facilities can be operated in an environmentally acceptable manner. Neither alternative, however, has gained general public acceptance, and planned projects are often controversial. There remains considerable skepticism, for example, that landfill liners will be effective over long periods of time, and a general uneasiness over the safety of waste combustion. The interest in emerging conversion technologies, such as gasification and anaerobic digestion, as an alternative to conventional landfills and WTE facilities is thus understandable. However, there is some concern that the environmental impacts of conversion technologies are not well understood, as no commercial facilities exist in the United States. Development of a risk assessment framework for evaluating conversion technologies will serve two purposes. First, it will ultimately facilitate objective evaluation of potential risks to health and the environment as well as comparative evaluation with respect to traditional landfill and WTE technologies. Second, it will initiate a conceptual model of environmental impacts that will be useful in identifying key emissions and data gaps. Our presentation will set forth an initial risk assessment framework, focusing on the emissions and residuals of conversion technologies, and using available data to characterize and project health risk impacts. NOMENCLATURE EC – European Commission HAP – Hazardous Air Pollutant MPRA – Multi-pathway risk assessment MSW – Municipal solid waste NAAQS – National Ambient Air Quality Standard PCDD/PCDFs – Polychlorinated dibenzo(p)dioxins and furans Syngas – Synthesis (combustible) gas WTE – Waste-to-energy INTRODUCTION New waste conversion technologies are being proposed with growing frequency as an alternative means of disposing of residual (post recycling) municipal solid waste. In part, the emergence of novel waste conversion technologies has resulted from a desire to move away from the conventional landfill and waste-to-energy approaches, which are perceived to have negative environmental consequences. One area of concern and means of comparison among solid waste management technologies centers on the release of air pollutants. So-called “criteria” pollutants, which include particulate matter, sulfur dioxide, nitrogen oxides, and carbon monoxide, are typically emitted in the largest quantities and are subject to well-defined regulations designed to meet and maintain National Ambient Air Quality Standards (NAAQSs). Greenhouse gas emissions, often based on life cycle analyses, are another relevant concern. However, it is the so called “air toxics,” a category of