Health risk assessment components

Figure 8.1 Overview of Human Health Risk Assessment Components and Process...

List tire four main components of health risk assessment and explain them briefly. 

The exposure assessment characterizes the pathways, magnitude, frequency, and duration of human exposures from various sources. Chapter 5 provides an overview of these components and addresses the principles of exposure assessment in children. General principles of exposure assessment have been reviewed in a number of publications (USEPA, 1992a, 2005a IPCS, 1999a, 2000 Needham et al., 2005). This chapter will focus on the considerations that are important when applying the exposure data to a children s health risk assessment (see Box 2). 

Risk assessment is a process where the magnitude of a specific risk is characterized so that decision-makers can conclude whether the potential hazard is sufficiently great that it needs to be managed or regulated, reduced or removed. The National Research Council (NRC, 1983) of the National Academy of Sciences (NAS) first described the process of human health risk assessment, with an update in 1994 and 1996, as a four-component paradigm (i.e., hazard identification, dose-response assessment, exposure assessment, and risk characterization), with risk communication as a fifth area of study. The first four components are described briefly below. 

Some reviewers of earlier drafts of this interim framework proposed that the term "exposure" — which, as used in human health risk assessment, generally refers to chemical stressors — not be used for the nonchemical stressors that can affect a variety of ecological components. Other terms, including "characterization of stress," have been suggested. At this time, EPA prefers exposure, partly because characterization of stress does not convey the important concept of the co-occurrence and interaction of the stressor with an ecological component as well as exposure does. 

Many fundamental concepts of human health risk assessment from chemical and biological hazards have been described in Risk Assessment in the Federal Government Managing the Process (NRC, 1983). The basic paradigm developed in that report is shown in Figure 6-1, and it captures the two key components—risk assessment and risk management—that apply equally well to building protection situations. 

Health risk assessment has 4 major components hazard identiHcation dose-response assessment exposure assessment and, risk characterization. 

Part 4 continues with lead-specific discussions of the four components of a human health risk assessment as structurally articulated in 1983 by the NAS/NRC (1983) Chapter 21, human health hazard characterization for lead and diverse human populations Chapter 22, dose—toxic response relationships for lead in humans Chapter 23, illustrative uses of case- or setting-specific lead exposure characterizations and. Chapter 24, the last part of health risk assessment, the overall final and most quantitative step in actualizing (in a relative sense) the estimates of risk outcomes. 

TABLE 20.1 Components of Human Health Risk Assessment for Pb and Their Databases in This Book ... 

THE COMPONENTS OF CONVENTIONAL HUMAN HEALTH RISK ASSESSMENT... 

Lead would appear to be a particularly valuable, even unique, model for assessing human health risk assessments for toxic environmental contaminants. There are several factors establishing that status. The first is the amount of available data and the nature of that data. Second, we can identify subsets of human populations at particular risk for both exposure to and toxic effects of lead. Third, the available data for Pb and public health readily partition into the typical components of risk assessment. Finally, all data components present with acceptable quality in the nature and extent of the information. 

The organization of this portion of the book broadly follows the sequence of risk assessment components recommended in the 1983 NAS/NRC report on risk assessment in the Federal government. That report s generic organization is often relied on by public agencies such as the U.S. EPA in its protocols and documents dealing with various mandated environmental health activities for contaminants such as lead. 

The time-dependent human health hazard characterization for lead is best summarized by chronological blocks of time and those adverse health effects that were considered of medical or scientific importance. Associated with the various levels of adverse health effect severity are body lead burdens or dose. The combination of these dose ranges, whether measured at the time or retroactively imputed as likely lead doses given current knowledge, defines the dose—response relationship, also called the dose—effect severity relationship. This topic as the third component of health risk assessment is addressed in Chapter 22. 

Figure 1.1 depicts the three components of an overall interactive feedback-loop relationship that is tripartite in nature, involving scientific research, health risk assessment, and the regulation of lead in the human environment. Scientific research informs both risk assessment and regulatory initiatives. Subsequent needs for adequate risk assessment and stronger, more effective regulation then dictate that there be more research. Adequate regulation is also informed by adequate human health risk assessments, subsequent... 

The standardized human health risk assessment methodology generally includes the following four components ... 

The objective of the data evaduation component of a human health risk assessment is to define the nature and extent of chemical contamination at a site. This could include taking soil and/or groundwater samples to identify what chemicals are present, where they are present, and at what concentrations. This information provides the foundation for the risk assessment. 

There are two components to the analysis phase characterization of exposure and characterization of effects. Overall, this phase is similar to the exposure and toxicity assessment components of a human health risk assessment. The primary differences relate to the variety of ways in which exposure and toxicity can be measured in an ecological risk assessment. 

The component of a human health risk assessment in which a conceptual site model and chemical-specific dose estimates are made. 

Table 16.9 lists five remedial alternatives and their primary components. The nonaction alternative (Alternative 1) provides a baseline for comparison of other alternatives. Because no remedial activities will be implemented with the nonaction alternative, long-term human health and environmental risks for the site essentially will be the same as those identified in the baseline risk assessment. All other action alternatives with action have four common components ... 

There is a growing need to better characterize the health risk related to occupational and environmental exposure to pesticides. Risk characterization is a basic step in the assessment and management of the health risks related to chemicals (Tordoir and Maroni, 1994). Evaluation of exposure, which may be performed through environmental and biological monitoring, is a fundamental component of risk assessment. Biomarkers are useful tools that may be used in risk assessment to confirm exposure or to quantify it by estimating the internal dose. Besides their use in risk assessment, biomarkers also represent a fundamental tool to improve the effectiveness of medical and epidemiological surveillance. 

An alternative to identifying organic chemicals in water and then determining their biological activity is the direct bioassay of mixtures accumulated from drinking water. This approach can provide part of the data for the preliminary assessment of health risks. The data can also be used to select those water sources on which the most strenuous identification efforts should be directed. Mixtures exhibiting considerable activity can be separated into chemical classes and bioassays can then be used to identify the active fractions. Ultimately the individual culprit chemicals would be identified. In this manner, efforts are directed towards the more detrimental components. 

Article l(28)a of Directive 2004/27/EC defines the risk-benefit balance as an evaluation of the positive therapeutic effects of the product in relation to the risks to patients or public health. The environmental component of the definition of risks is excluded from the risk-benefit balance. Under the new legislation, the risk-benefit balance is considered as part of Article 23 (which enables the competent authority to continuously assess the risk-benefit balance by requesting relevant data from MAH), and Article 104 (relating to the submission by MAH of PSURs). 

---