The risk assessment process

The passage of SARA in 1986 resulted in the development of applicable or relevant and appropriate requirements (ARARs), which are used as de facto values for cleanup end points. The ARARs are usually based on other environmental laws, such as the SDWA or the RCRA. 

Universal across-the-board cleanup criteria are not commonly used as end points for soil and groundwater cleanup, because of the wide range of risks found at these sites. However, two classes of contaminants have been subject to universal action levels for cleanup petroleum and polychlorinated biphenyls (PCBs). Most petroleum hydrocarbon action levels are regulated by state and local agencies the parameters used and their corresponding action levels vary widely from state to state. The specific petroleum parameters that are regulated include total petroleum hydrocarbon— gasoline fraction (TPH-G) total petroleum hydrocarbon—diesel component (TPH-D)  

In the United States, PCBs are regulated under the TSCA. The universal standard for total PCBs (i.e., the total of all 209 congeners) in commercial 

Hazardous waste problems are frequently generated by mixtures of complex wastes that have been disposed of on land and that have migrated through the subsurface. One approach to assessing the risks of contaminated sites has been to divide the problem into three elements sources, pathways, and receptors (Watts, 1998) as noted in Table 2. The first step in assessing the risk at a hazardous waste site is to identify the waste components at the source, including their concentrations and physical properties such as density, water solubility, and flash point. After the source has been characterized, the pathways of the hazardous chemicals are analyzed by quantifying the rates at which the 

Time since environmental release Contaminants potentially present Sampling 

The HSE approach to risk assessment (5 steps) will be used to discuss the process of risk assessment. It is, however, easier to divide the process into six elements  

Hazard identification is the crucial first step of risk assessment. Only significant hazards, which could result in serious harm to people, should be identified. Trivial hazards should be ignored. 

A tour of the area under consideration by the risk assessment team is an essential part of hazard identification as is consultation with the relevant section of the workforce. 

A review of accident, incident and ill-health records will also help with the identification. Other sources of information include safety inspection, survey and audit reports, job or task analysis reports, manufacturers handbooks or data sheets and approved codes of practice and other forms of guidance. 

Hazards will vary from workplace to workplace but the checklist in Appendix 5.1 shows the common hazards that are significant in many workplaces. 

There are a number of different methodologies that are currently used throughout industry and commerce to achieve a systematic approach to risk assessment. In 

In its own fire safety guidance documents HM Government has adopted a very similar approach in its guidance on how an assessment of fire risks can be achieved (Chapter 14). 

The above steps identify the basic process of risk assessment and are discussed in more detail later in this chapter. 

In order for organisations to conduct suitable and sufficient risk assessment and ensure that all risks arising from work activities are identified, evaluated and effectively controlled it is necessary to adopt a systematic approach to conducting risk assessments. It is likely that any such approach which require organisations to perform the following stages  

Evaluating the levels of residual risk taking into account the risk control measures that are already in place 

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Risk Assessment (RA) is routinely used in setting air standards. Give the sequence of steps in the risk assessment process. 

Andersen ME, Clewell HJ 3rd, Gargas ME, et al. 1987. Physiologically based pharmacokinetics and the risk assessment process for methylene chloride. Toxicol Appl Pharmacol 87 185-205. 

The sheer complexity of environmental mixtnres of EDCs, possible interactive effects, and capacity of some EDCs to bioaccumulate (e.g., in fish, steroidal estrogens and alkylphenolic chemicals have been shown to be concentrated up to 40,000-fold in the bile [Larsson et al. 1999 Gibson et al. 2005]) raises questions about the adequacy of the risk assessment process and safety margins established for EDCs. There is little question that considerable further work is needed to generate a realistic pictnre of the mixture effects and exposure threats of EDCs to wildlife populations than has been derived from studies on individual EDCs. Further discussion of the toxicity of mixtures will be found in Chapter 2, Section 2.6. 

Professor Martel s book addresses specifically some of the more technical eispects of the risk assessment process, mainly in the areas of hazard identification, and of the consequence/effect analysis elements, of the overall analysis whilst where appropriate setting these aspects in the wider context. The book brings together a substantial corpus of information, drawn from a number of sources, about the toxic, flammable and explosive properties and effect (ie harm) characteristics of a wide range of chemical substances likely to be found in industry eind in the laboratory, and also addresses a spectrum of dangerous reactions of, or between, such substances which may be encountered. This approach follows the classical methodology and procedures of hazard identification, analysing material properties eind... 

The risk assessment process has the capacity to dimension, to rank, to focus and to test the sensitivities, the interdependence and the interactive responses of all these component elements. 

Ecotoxicological data based on Organization for Economic Cooperation and Development (OECD) guidelines are also required, and the endpoints for aquatic organisms, such as fish, daphnia, algae and aquatic plants, are needed for utilization as part of the risk assessment process. 

Before deciding to develop a system in-house, the following points must be factored into the risk assessment process ... 

The risk assessment process begins by identifying specific accident scenarios that apply to the facility under review. Steps include ... 

When any decisions regarding process plant buildings are to be made, it is important that the uncertainties in the risk assessment process be clearly understood and that these uncertainties be a consideration in the decision making. 

In recognition of the increased vulnerability of the developing organism, both the U.S. EPA Food Quality Protection Act [77] and the U.S. EPA Safe Drinking Water Act [78] mandate that infants and children warrant special consideration in the risk assessment process. Immune system ontogeny and the sensitivity of the developing immune system to xenobiotics are discussed in detail in chapter 20 of this volume. 

From those techniques given in Table 1 my personal preference is for failure mode, effects, and criticality analysis (FMECA). This technique can be applied to both equipment and facilities and can be used to methodically break down the analysis of a complex process into a series of manageable steps. It is a powerful tool for summarizing the important modes of failure, the factors that may cause these failures, and their likely effects. It also incorporates the degree of severity of the consequences, their respective probabilities of occurrence, and their detectability. It must be stressed, however, that the outcome of the risk assessment process should be independent of the tool used and must be able to address all of the risks associated with the instrument that is being assessed. 

The determination of the estimated levels of exposure is obviously a critical component of the risk assessment process. Both pesticide residue levels and food consumption estimates must be considered. Methods for determining exposure are frequently classified as deterministic and probabilistic methods (Winter, 2003). 

The subjects of NOAELs and LOAELs are critical to the risk assessment process, and we shall he referring to them throughout the hook. 

The remaining sections of this chapter are concerned with the scientific difficulties encountered in the practice of risk assessment - in fact, it will be seen that there are critical aspects of the risk assessment process that cannot be adequately dealt with because of limitations in scientific understanding. Following this chapter is another on risk assessment, devoted to its practical applications, and then comes a third chapter providing examples of some new risk assessment challenges and approaches. After a final brief chapter on risk assessment in the courtroom, risk management returns in Chapter 11. 

This use of animal evidence is based, in part, upon its scientific standing, but it is also based upon a science policy decision - it is one of the defaults present in the risk assessment process. Even in the absence of specific knowledge that the response detected in a toxicology study is relevant to humans, it will be assumed to be so -unless other data arrive to demonstrate that it is not relevant to humans (see below what is meant by other data ). Regulators and public health policies generally call for action even when the evidence regarding adverse health effects does not rise to the level necessary to establish causation in humans. 

These three commonly encountered problems in dealing with the dose-response step of the risk assessment process (and there are others as well) are respectively referred to as the problems of (1) high-to-low dose extrapolation (2) extrapolation across exposure durations ... 

Most scientists would hold that these unknowns and uncertainties in the regulatory risk-assessment model would tend to favor risk overestimation rather than underestimation or accurate prediction. While this view seems correct, it must be admitted that there is no epidemiological method available to test the hypothesis of an extra lifetime cancer risk of about 10 per 1000 000 from methylene chloride in drinking water. The same conclusion holds for most environmental carcinogens. It is also the case that more uncertainties attend the risk assessment process than we have indicated above. 

If it is possible to acquire an adequate understanding of pharmacokinetics, it may be possible in specific cases to document (1) changing pharmacokinetic patterns with changing dose or (2) pharmacokinetic patterns in the animal species used to develop toxicity data that are substantially different from those seen or expected in humans. Such differences would document that the usual defaults do not hold in those specific cases. The effects of using pharmacokinetic data in the risk assessment process instead of the usual defaults would depend upon what those data actually revealed. 

Calabrese, E. J. and Cook, R. R. (2005) Hormesis how it could affect the risk assessment process. Human and Experimental Toxicology. 24, 365-270. 

PBPK models improve the pharmacokinetic extrapolation aspects of the risk assessment process, which seeks to identify the maximal (i.e., safe) levels for human exposure to chemical substances (Andersen and Krishnan 1994). PBPK models provide a scientifically sound means to predict the target tissue dose of chemicals in humans who are exposed to environmental levels (for example, levels that might occur at hazardous waste sites) based upon the results of studies where doses were higher or were administered in different species. Figure 2-4 shows a conceptualized representation of a PBPK model. 

FIGURE 1.2 The risk assessment process from data collection to risk characterization. 

The Risk Assessment process includes four steps hazard identification, hazard characterization (related term dose-response assessment), exposure assessment, and risk characterization. It is the first component in a risk analysis process. 

Risk Characterization is the fourth step in the Risk Assessment process. 

For both human health and the environment, the risk assessment process includes (i) an exposure assessment, (ii) an effect assessment (hazard assessment and hazard characterization -addressed in detail in Chapter 4), and (iii) a risk characterization (addressed in detail in Chapter 8). As a part of the effect assessment, classification and labeling of the substance according to the criteria laid down in Directive 67/548/EEC (EEC 1967) is also addressed (Section 2.4.1.8). 

The first draft of the risk assessment reports are written by the Member States, which act as rapporteurs . Generally, one Member State acts as rapporteur for a prioritized substance or group of substances however, for some prioritized substances, more than one Member State can act as rapporteurs. The risk assessment process is coordinated by the ECB. Stakeholders are involved in the process through the Technical Committee for New and Existing Substances (TC NES). The Commission mediates the meetings, which attempt to reach consensus on the conclusions of the risk assessments. During the risk assessment process, the Scientific Committee on Health and Environmental Risks (SCHER) is requested to provide an opinion. 

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