Loading...
Please wait, while we are loading the content...
Similar Documents
Principles and Approaches for Human Health Risk Assessment of Environmental Contaminants
| Content Provider | Scilit |
|---|---|
| Author | Fan, Anna M. Alexeeff, George Khan, Elaine |
| Copyright Year | 2015 |
| Description | Book Name: Toxicology and Risk Assessment |
| Abstract | The views expressed are those of the author and do not necessarily represent those of the New Jersey Department of Environmental Protection. 1.1 IntroductionSince its introduction more than 30 years ago, human health risk assessment continues to be an essential component of evaluation and decision making about environmental contaminants to which humans are exposed. This chapter provides an overview of the general risk assessment process, including recent refinements and advances, as well as future directions as currently envisioned. The information presented here is intended to provide a useful starting point for understanding of the subsequent chapters which discuss specific aspects relating to chemical toxicity and risk assessment. Human health risk assessment is defined by the United States Environmental Protection Agency (USEPA) as “the process to estimate the nature and probability of adverse health effects in humans who may be exposed to chemicals in contaminated environmental media, now or in the future” [1]. Risk assessment, along with other types of information, is used in the evaluation and regulation of en-vironmental contaminants. This chapter provides a brief introduc-tion to the principles and approaches used for human health risk assessment of environmental contaminants, focusing primarily on approaches used by the USEPA. Specific aspects of risk assessment and case studies are discussed in detail in subsequent chapters, as well as in the references cited herein. Approaches used by states (e.g., California [2] and New Jersey [3]), and other US federal agen-cies (such as the Agency for Toxics Substances and Disease Registry [ATSDR] [4]), are generally based on those of the USEPA. Discussion of a related process, ecological risk assessment [5], which address-es ecological impacts of environmental contaminants, is beyond the scope of this chapter. Stern [6] provides useful perspectives on many of the human health risk assessment issues mentioned in this chapter. Human health risk assessment methodologies used in other nations are largely similar in concept to those of the USEPA, although they may differ in specific details [7]. An alternative approach to decision making about human exposure to environmental contaminants is based on the precautionary principle, generally meaning that protective measures should be taken if there is uncertainty about potential risks of serious or permanent effects even when these risks have not been definitively demonstrated. The precautionary principle has been considered in the development of some policies related to human exposure to potentially harmful substances, particularly by the European Union [7]. Human health risk assessment seeks to address issues about environmental contaminants such as the nature of the health effects that they may cause, the levels of human exposure from various environmental media, the impacts of human activity patterns on exposures, the doses and exposure durations at which health effects may occur, the probability of health effects from different levels of exposure, and factors that may result in greater exposures and/or greater susceptibility to health effects in specific subpopulations. The results of human health risk assessments are used, along with other information, in many different types of decision making related to environmental contamination. Some examples include ad-vice for action in emergency situations such as industrial accidents or spills of transported materials, the human health basis of chemical-specific regulatory standards and guidance levels, decisions about manufacture and use of pesticides and other toxic substances, and assessment of potential health risks at contaminated sites. The duration of exposure of interest for a risk assessment (acute, intermediate, or chronic) depends on the situation to which the results will be applied. For example, many regulatory standards are based on the assumption of lifetime exposure, cleanup of residential sites is often based on the assumption of 30 years of residence, and shorter-term exposures (e.g., a few days) may be the relevant time period for exposure to water or air contaminants from an accident or other nonrecurring release that will quickly dissipate. Definitive information on health effects in human populations exposed to contaminants at the levels that are found in the environment is the most directly relevant for risk assessment, but such data are rarely available. To be protective of public health, exposures to environmental contamination must be addressed within a reasonable time frame. Therefore risk assessments must often be developed on the basis of the information that is available even if it is incomplete. Data from animal toxicology studies, or less commonly, epidemiology studies of workers with exposures far above environmental levels, are most often used as the primary basis for risk assessment. Uncertainties are involved in the interspecies extrapolation of data from experimental animals to potential effects in humans, as well as the extrapolations from the higher doses usually used in the animal studies or typically present in the workplace to environmental exposures that are generally much lower. In the absence of chemical-specific data, default assumptions are used to address these uncertainties and data gaps. Since the risk assessment process is intended to be protective of public health, the assumptions used to address these uncertainties are intended to be reasonable but conservative so that risk is not likely to be underestimated [8]. If data becomes available to address sources of uncertainty, the risk assessment can be revised to replace the assumption with chemicalspecific information based on this data. The level of uncertainty that is considered to be acceptable may vary depending on the purpose of the risk assessment. When a risk assessment is urgently needed to provide advice in an emergency... |
| Related Links | https://content.taylorfrancis.com/books/download?dac=C2015-0-59528-9&isbn=9780429183720&doi=10.1201/b18228-4&format=pdf |
| Ending Page | 76 |
| Page Count | 32 |
| Starting Page | 45 |
| DOI | 10.1201/b18228-4 |
| Language | English |
| Publisher | Informa UK Limited |
| Publisher Date | 2015-03-04 |
| Access Restriction | Open |
| Subject Keyword | Book Name: Toxicology and Risk Assessment Decision Making Toxic Substances Environmental Contaminants Intended Risk Assessment Process Exposed Effects in Humans |
| Content Type | Text |
| Resource Type | Chapter |
