Risk assessment general principles

Lovell, D.P., Risk assessment — general principles , in Toxic Hazard Assessment of Chemicals, Richardson, M.L. (Ed.), The Royal Society of Chemistry, London, 1988, pp. 92-113. 

The statutory guidance describes how, in general terms, the assessment of land under the new regime should be based on the principles of risk assessment. These principles have been applied in areas such as chemical safety testing for many years and they include a recognition that risk is a function of hazard and exposure. In simple terms, this means that the mere presence of a hazardous substance on a site is not indicative of a need for clean-up. Instead, it is a trigger for further examination of the likelihood of harm occurring, or that such harm has already occurred, prior to a decision on whether or not clean-up is warranted. 

Recognised test methods include methods developed by internationally recognised agencies such as DIN, ISO, CEN or OECD. As a general principle, the lowest test result for the most sensitive species has to be used as the starting point for the risk assessment and for the derivation of the water and biota quality norms. The toxicity data used for the risk assessment have to be examined critically with respect to validity and relevance. 

While the basic principle of inherently safer design is generally accepted, it is not always easy to put it into practice. Inherently safer design has been advocated since the explosion at Flixborough in 1974. Progress has been real but nevertheless the concept has not been adopted nearly as rapidly as quantitative risk assessment, introduced into the chemical industry only a few years earlier (Kletz, 1996). 

A CSR is a risk assessment, following the general provisions of Annex I of the proposed REACH Regulation, with extra guidance in Annex IB for substances that are components of preparations. These general principles correspond with the current EU practice for notified new substances and priority existing substances, as described more fully in Section 14. The ECA will develop software to help registrants prepare the CSR. It is essential to have input from downstream users to prepare the risk assessment for the CSR, which... 

There are occasional outbursts of skepticism about the value of the risk assessment approach. Some argue its full use is overly burdensome, that the only real need is to identify toxic chemicals and then eliminate them or reduce their presence. Perhaps this approach is appropriate for a few chemicals that exhibit extremely high toxicity or that are excessively persistent and bioaccumulate in an environment, and for which there are reasonably good substitutes available. But as a general approach, it ignores the elementary principle that all chemicals will... 

Figure 4. General principle of risk assessment for new substances, existing substances and biocides...

The US-EPA staff paper from 2004 titled An Examination of EPA Risk Assessment Principles and Practices (US-EPA 2004) is a product of a US-EPA staff review of how risk assessment is conducted at the Agency. US-EPA assembled a group of risk assessment professionals from across US-EPA to examine US-EPA s risk assessment principles and practices and to prepare the paper. The staff paper presents an analysis of US-EPA s general risk assessment practices and provides comprehensive and detailed information on the practices employed. 

The series of Risk Assessment Guidelines includes a guideline for neurotoxicity risk assessment (US-EPA 1998). This Guideline sets forth principles and procedures to guide US-EPA scientists in evaluating environmental contaminants that may pose neurotoxic risks, and inform US-EPA decision-makers and the public about these procedures. The Guideline includes a discussion of general dehnitions and issues, an overview of test methods, and the interpretation of data within the U.S. framework for risk assessment. 

Uncertainty analysis is increasingly used in ecological risk assessment and was the subject of an earlier Pellston workshop (Warren-Hicks and Moore 1998). The US Environmental Protection Agency (USEPA) has developed general principles for the use of Monte Carlo methods (USEPA 1997), which provide one of several approaches to incorporating variability and uncertainty in risk assessment. 

Guidance to date supports the risk assessment principles for general chemical substances already published by the Commission (1996). Consequently, the risk characterisation simply involves a quantitative comparison of the outcome of the hazard/effects assessment with the exposure assessment. For human risk this involves the calculation of the TER (Toxicity Exposure Ratio) and comparing it with the MOS (Margin Of Safety). For environmental risk the PEC/PNEC ratio (Predicted Environmental Concentration versus the Predicted No-Effect Concentration) for the various environmental compartments. 

The partition coefficient (K ) was used for the conversion of TBT concentrations in sediment and SPM to TBT concentrations in water. This Kp for TBT was calculated by multiplying the organic carbon partition coefficient (K ) with the measured fraction organic carbon (f ). Consequently, the K value has a strong impact on the final results of the risk prognosis. Generally, in risk predictions the lowest K value is applied to calculate concentrations in water (EC, 2003). This results in a worst-case water concentration, in accordance with the precautionary principle. However, with literature values for the K of TBT ranging from 3.0 - 6.2 (Lepper, 2002), it is more appropriate to base an assessment on local measured values. In this study the... 

Walsh, C.T. 1990. Anatomical, Physiological, Biochemical Characteristics of the Gastrointestinal Tract. Iln T.R. Gerrity and C.J. Henry, Eds., Principles of Route-to-Route Extrapolation for Risk Assessment, pp 33-50. Elsevier New York, N.Y.Wester, R.C., and H.I. Maibach. 1997. Toxicokinetics Dermal Exposure and Absorption of Toxicants. In I.G. Sipes, C.A. McQueen, and A.J. Gandolfi, Eds., Comprehensive Toxicology Volume General Principles (J. Bond, volume editor), pp. 99-114. Pergamon Press, New York, N.Y. 

USEPA (2000). General Principles for Performing Aggregate Exposure and Risk Assessments, Report No. 6040, Office of Pesticide Programs and Office of Prevention, Pesticides and Toxic Substances, (http //www.epa.gov/pesticides/trac/science/) Washington, DC, November 21. 

This chapter has outlined the general principles of the use of extrapolation in criteria setting and risk assessment. Extrapolation is used in the setting of criteria, where only effects are considered, as well as in risk assessments, where both effects and exposures are considered. In formulating approaches to criteria setting and risk assessment, tiers are often used to simplify the process. In keeping with the... 

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). 

Kacew S (1992) General principles in pharmacology and toxicology applicable to children. In Guzelian PS, Henry CJ, Olin SS eds. Similarities and differences between children and adults Implication for risk assessment. Washington, DC, ILSI Press. 

This chapter is subdivided into 4 main parts. The first part introduces the fundamental principles of toxicokinetics and toxicodynamics, and their importance for risk assessment, with particular emphasis on mixtures. The second part describes the state of the art in toxicokinetics, and the third part in toxicodynamics. Both later sections focus on how each aspect is dealt with in human toxicology and ecotoxicology. The differences and limitations in each field are addressed. Finally, a general discussion, conclusions, and recommendations for future research explore the application potentials of these approaches, with particular attention to cross-fertilization between human toxicology and ecotoxicology, and where they may hold some promises. 

Several steps have been taken towards a more harmonised methodology within the more general area of risk assessment of chemicals. The EU has proposed a number of principles for assessment of risks to man and the environment in directive 93/67/EEC (EC 1993) as well in the Technical guidance documents in support of directive 96/67/EEC on risk assessment (EC 2003), to further common practices in risk assessment. A harmonisation of national exposure limits is to be expected, since the EU sets both binding and indicative OELs for each member state to consider in its national regulations. However as noted by Vincent (1998) a full international harmonisation of OELs is unlikely and may not even be the most... 

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