7.4 Risk assessment methodology for conventional and alternative

Learning objectives

After reading this module, students should be able to

• understand the content and the goals of four-step of risk assessment process
• know how to estimate dose received via each exposure pathway
• know how to integrate exposure and toxicity information to characterize health risks
• understand how to quantitatively estimate cumulative cancer and noncancer risks
• understand how to identify/evaluate uncertainties in risk assessment

Introduction

Risk assessment is a scientific process used by federal agencies and risk management decision-makers to make informed decisions about actions that may be taken to protect human health by ascertaining potential human health risks or health hazard associated with exposure to chemicals in the environment.

Some of the real-world examples of risk assessment includes: establishment of national ambient air quality and drinking water standards for protection of public health (e.g. ozone, particulate matter in outdoor air; chromium, chloroform or benzene in water); establishment of clean-up levels for hazardous waste site remediation; development of fish consumption advisories for pregnant women and general population (e.g. PCBs, mercury); assessment of risks and benefits of different alternative fuels for sound energy policy development (e.g. oxygenated gasoline, biodiesel); and estimation of health risks associated with pesticide residues in food. The estimated risk is a function of exposure and toxicity, as described in detail in NAS ( 1983 ) and EPA ( 1989 ). The regulatory risk assessment follows a four-step paradigm using qualitative and/or quantitative approaches. In quantitative risk assessment using either deterministic or probabilistic approaches, the risk estimates pertaining to an exposure scenario is particularly useful when comparing a number of exposure or risk reduction measures among one another as an optimization protocol to determine the best economically viable option for protection of public health and the environment. With environmental sustainability and life-cycle analysis in the forefront of green technological innovation, energy, and economic savings in the 21 ^st Century, risk assessment will pay a pivotal role in discerning the option(s) with the most benefit in health protection and, thus, will be an integral part of any environmentally sustainability analysis. Such comparative risk assessment can be performed for traditional approaches vs. environmentally sustainable approaches. They can also be performed among different environmentally sustainable options for an environmental pollution problem such hazardous waste site remediation and redevelopment, air quality management in urban areas, pest management practices, agricultural health and safety, alternative energy sources for transportation sources and among others.