Risk Assessment in Practice

Risk assessments in a quantitative fashion can be carried out, but assumptions that must be made to do so may overestimate or underestimate the actual risk, even by orders of magnitude. Regulators therefore often convert an acceptable dose such as a NOEL into a realistic conservative estimate by dividing the calculated value by a factor as great as 1,000. It is tempting to simply equate risk with hazard or toxicity (precautionary principle), thus eliminating the need to consider exposure and make conservative assumptions. 

It is beyond the scope of this publication to delve completely into the nuances of detailed quantitative risk assessments, but a few typical considerations can be presented. As an example, we will consider the risk assessment for ethylene glycol recently carried out by Health Canada (HC) in its second Priority Substance Listing (PSL2) assessment for the chemical, as required under the Canadian Environmental Protection Act (CEPA) of 1999. Ethylene glycol represents an interesting example because humans and the environment can potentially be exposed due to its common use as the active component of anti-freeze and as a component of house paints. 

In its discussion of human health effects, HC used data obtained in animal studies and uncertainty factors to calculate a tolerable dose over a lifetime of exposure. Short-term exposure was evaluated separately. As stated in its report, HC concluded that long-term or chronic exposure to ethylene glycol is not likely to present a human health problem, but that short-term (acute) exposures to indoor air concentrations from certain consumer products may exceed a tolerable concentration using necessary conservative assumptions. The language that HC used to explain its findings and conclusions are as follows  

HC also characterises potential risk to the environment using an aircraft deicing operation as an example. Note in the summary below that considerations such as partition coefficients, bioaccumulation, and biodegradation are included in the analysis. The conclusion reached in this study is that ethylene glycol reaches the environment in quantities that would result in potential harm to it or its biodiversity. Note also the concluding statement that ethylene glycol is not toxic to the environment, the term toxic including exposure consideration for which we have used the term risk in this book. 

The direct comparison of exposure concentrations measured in the aquatic environment with the ENEV suggests that adverse effects are unlikely when consideration is given to the seasonal nature of releases, ambient temperatures, metabolic rates and duration 

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The European system for regulating synthetic chemicals, described in Chapter 5, is predominantly risk-based . This means that restrictions on the manufacture or use of chemicals must be justified by reference to evidence that there is a risk of the chemical causing a specified type of harm. REACH (Registration, Evaluation, Authorization and restriction of Chemicals) does not define the term risk , but the directive on risk assessment of new substances defined it as the incidence and severity of the adverse effects likely to occur [...] due to actual or predicted exposure to a substance (Article 2 of Directive 93/67/EEC). In the first part of this chapter I look at how risks from chemicals are assessed. What does chemicals risk assessment in practice aim to achieve Can it provide the reliable evidence needed for agreement by all parties on whether or not a chemical poses a risk My answer to this second question is no there are multiple uncertainties in chemicals risk assessment which lead to protracted debates as to whether a chemical poses a risk or not. 

Tough Leadership in ERM — Risk Assessment in Practice COSCO Enterprise Risk Management Integrated Frame Work, 2004. 

Henderson, R.F. 1992. Short-term exposure guidelines for emergency response The approach of the Committee on Toxicology. Pp. 89—92 in Conference on Chemical Risk Assessment in the Department of Defense (DoD) Science, Policy, and Practice, H.J.Clewell, III, ed. American Conference of Governmental Hygienists, Cincinnati, OH. 

The risk asses sment may include an evaluation of what the risks mean in practice to those effected. This will depend heavily on how the risk is perceived. Risk perception involves peoples beliefs, attitudes, judgements and feelings, as well as the wider social or cultural values that people adopt towards hazards and their benefits. The way in which people perceive risk is vital in the process of assessing and managing risk. Risk perception will be a major determinant in whether a risk is deemed to be acceptable and whether the risk management measures imposed are seen to resolve the problem. 

Practical Attempt Science-Based Framework of POPs Risk Assessment in China (ZHANG Aiqian, China)... 

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. 

The attempt to carry out risk assessment on a scientific basis has resulted in the systematic separation of risk assessment and practical risk management. An undesirable effect of this strict separation is the fact that the present practice of risk assessment does not produce the information that is required for formulation of risk management measures in a goal-oriented way. 

These four stages are identical to the four steps of the risk assessment process set out in a key 1983 US publication on risk assessment (NRC, 1983), demonstrating the influence of the US approach on Europe. It is recognized, however, that this model is not always appropriate, with ozone depletion being quoted as an effect for which stages 2 and 3 do not apply. In these cases regulators have to assess risks on a case-by-case basis and give a full description and justification of their assessments in their report to the Commission. In Chapter 7 I discuss how risk from chemicals are assessed in practice. 

S. M., Sanderson, H., Sibley, P.K. and van den Brink, P.J. (2008) Extrapolation for criteria setting and risk assessment, in Extrapolation Practice for Ecotoxicological Effect Characterization of Chemicals, (eds... 

Ratte, H.T., Baird, D.J., Nahholz, J.V. and Sanderson, H. (2008) Extrapolation of effects measures across levels of biological organization in ecological risk assessment, in Extrapolation Practice for Ecotoxicological Effect Characterization of Chemicals, (eds K.R. Solomon, T.C.M. Brock, D. de Zwart, S.D. Dyer, L. Posfhuma, S.M. Richards, H. Sanderson, P.K. Sibley and P.J. van den Brink), CRC Press/Taylor and Francis/SETAC, Pensacola, FL,... 

Like homologs, TEQs bury a lot of useful information. If TEQs are reported exclusively, it is very difficult to use the information for any purposes other than the intended one. The tendency in recent years to report TEQs in air and sediment using mammal-based WHO TEFs to satisfy human risk assessments (Sects. 2.1 and 2.3) obviates using these data for risk assessment in fish and birds. It is understandably not feasible to present all the AHR congener-specific data in these reports, however, it would not be all that difficult to generate a complete set of TEQs for fish and birds as well as mammals, and wherever possible, authors should make congener concentrations available. I strongly recommend that this become standard practice. 

PAUSTENBACH, D.J. (1995). The practice of health risk assessment in the United States (1975-1995) How the United States and other countries can benefit from that experience, Hum. Ecol. Risk Assess. 1, 29—79. 

In March 1982 the American Chemical Society sponsored a symposium on risk assessments of hazardous chemical waste sites, and the chapters of this volume are the final versions of the papers that were presented and discussed at this symposium. The first chapters present the problem the history of the development of Superfund legislation and the arguments about the most appropriate approaches to risk assessments, specific cases of hazardous waste problems in Louisiana, the problems of Love Canal and their bearing on risk assessment, and the impacts on human health that can result from hazardous waste sites. The next broad topic of the symposium was the central problem of methodology of risk assessment. The practical problems that confront the field teams who examine specific chemical waste sites are what to monitor, how to monitor, and how to have reasonable assurance of the reliability of the results of monitoring. A final chapter considers a problem of central importance to the Superfund effort how to incorporate risk assessment into the regulatory process. 

This brief review has shown that there are some differences in the way dietary risk assessment is practiced between the US and the EU. Many of the differences have to do in the types of input data that are available, or in some of the methods used to collect the data. Regarding the food consun tion data, the US surveys use a dietary recall method, whereas the UK approach is a diary method that weighs and measures the amount of food consumed. In the US, data are collected for two non-consecutive days, whereas in the UK surveys, data are collected for either 4 or 7 consecutive days. The US survey is conducted as an integrated whole and includes all segments of the population. In contrast, the UK surveys are conducted for specific population groups. Finally, the US survey collects data at the household level, whereas the UK survey targets demographic characteristics, based upon census information. 

In general CFD models show a good applicability for risk assessments in urban areas however, their results can differ depending on turbulent closure models and other assumptions (Schatzmann, 2005 [562]). For practical applications these models contain a substantial amount of empirical knowledge, not only in the turbulent closure schemes but also in the use of wall functions and in other parameterisation schemes. To cast doubt on the results is perfectly justified, as it was shown by systematic studies in which applications of the same model by different modellers to a given problem (Hall, 1997 [244]) and applications of different models by either the same or different modellers to the same problem (Ketzel et al., 2002 [332]) revealed significant differences. 

While risk assessment in the context of protecting public health has been performed for many years, it is the 1983 U.S. National Academy of Sciences Report (Committee on the Institutional Means for Assessment of Risks to Public Health Commission on Life Sciences National Research Council 1983) that has served as the tenet for practicing risk assessors (see Chapter 1). Risk assessment was defined as the characterization of the potential adverse health effects of human exposures to environmental hazards. The predictive aspect of risk assessment was set by the use of the word potential. A fundamental expectation of the risk assessment process was that it should attempt to accm-ately predict adverse effects before there is evidence of disease in the population. Thus, risk assessment goes beyond the mere description of epidemiological and clinical case-control studies. In that report, the committee defined logical components of a risk assessment which still serve as guiding principles today. They were and are (a) hazard assessment or the qualitative determination that a stressor poses a hazard as evidence by causal evidence of an ill effect,... 

Ecological risk assessment differs importantly from human health risk assessment in that the latter attempts to extrapolate effects of chemicals on a handful of model species to 1 target species (humans), whereas the former attempts to extrapolate effects on a handful of model species to all species in potentially exposed ecosystems. Even if it were possible to test all species in all ecosystems (which it is not), there would be both moral and economic reasons for not wishing to do so. Ecological models are the only practical way to cover the range of situations for which we wish to estimate risk. 

For risk assessment in the case of vanadium uptake urine is the matrix of choice. The collection of urine is non-invasive and is practical under routine conditions. Moreover this parameter is more sensitive for diagnostic purposes than the vanadium concentration in blood. A tentative biological threshold limit value of 50 mg/kg creatinine has been proposed for urinary vanadium (Lauwerys, 1983). 

It is important to remember that all these tests should be preceded by an appropriate risk assessment in order to implement all the reasonable health and. safely measures. For instance the use of such toxic chemicals as dichloromethane is the subject of COSHH (Control of Substances Hazardous to Health) regulation. Other activities where latent energy is involved, as in the application of hydrostatic pressure, and scattering of specimen debris from a fracture test, also pose a degree of hazard. Obviously the full circumstances are best known to the actual people engaged in any specific work, and therefore they are best placed to conduct a risk assessment and establish appropriate health and safety measures practices. 

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