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Sunday, 16 January 2011 19:01

Toxicology in Health and Safety Regulation

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Toxicology plays a major role in the development of regulations and other occupational health policies. In order to prevent occupational injury and illness, decisions are increasingly based upon information obtainable prior to or in the absence of the types of human exposures that would yield definitive information on risk such as epidemiology studies. In addition, toxicological studies, as described in this chapter, can provide precise information on dose and response under the controlled conditions of laboratory research; this information is often difficult to obtain in the uncontrolled setting of occupational exposures. However, this information must be carefully evaluated in order to estimate the likelihood of adverse effects in humans, the nature of these adverse effects, and the quantitative relationship between exposures and effects.

Considerable attention has been given in many countries, since the 1980s, to developing objective methods for utilizing toxicological information in regulatory decision-making. Formal methods, frequently referred to as risk assessment, have been proposed and utilized in these countries by both governmental and non-governmental entities. Risk assessment has been varyingly defined; fundamentally it is an evaluative process that incorporates toxicology, epidemiology and exposure information to identify and estimate the probability of adverse effects associated with exposures to hazardous substances or conditions. Risk assessment may be qualitative in nature, indicating the nature of an adverse effect and a general estimate of likelihood, or it may be quantitative, with estimates of numbers of affected persons at specific levels of exposure. In many regulatory systems, risk assessment is undertaken in four stages: hazard identification, the description of the nature of the toxic effect; dose-response evaluation, a semi-quantitative or quantitative analysis of the relationship between exposure (or dose) and severity or likelihood of toxic effect; exposure assessment, the evaluation of information on the range of exposures likely to occur for populations in general or for subgroups within populations; risk characterization, the compilation of all the above information into an expression of the magnitude of risk expected to occur under specified exposure conditions (see NRC 1983 for a statement of these principles).

In this section, three approaches to risk assessment are presented as illustrative. It is impossible to provide a comprehensive compendium of risk assessment methods used throughout the world, and these selections should not be taken as prescriptive. It should be noted that there are trends towards harmonization of risk assessment methods, partly in response to provisions in the recent GATT accords. Two processes of international harmonization of risk assessment methods are currently underway, through the International Programme on Chemical Safety (IPCS) and the Organization for Economic Cooperation and Development (OECD). These organizations also maintain current information on national approaches to risk assessment.



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