Measures of Response from Exposure to Hazardous Substances

1 Measures of Response from Exposure to Hazardous Substances 

Development of a comprehensive and risk-based hazardous waste classification system requires assumptions about the measure or measures of response (adverse health effects) from exposure to radionuclides and hazardous chemicals that should be used in classifying waste. Possible measures of response discussed in Section 3.2.3 include fatalities, incidence, or some combination of the two, such as total detriment (ICRP, 1991). The following sections discuss the measures of response from exposure to hazardous subtances that 

1 Measures of Response for Substances Causing Deterministic Responses. For purposes of health protection in routine exposure situations, incidence has been the primary measure of deterministic response for both radionuclides and hazardous chemicals. Fatalities also are of concern for substances that cause deterministic responses, but only at doses substantially above the thresholds for nonfatal responses. Given that the objective of standards for health protection is to prevent the occurrence of deterministic responses, incidence is not modified by any subjective factors that take into account, for example, the relative severity of different nonfatal responses with respect to a diminished quality of life. Judgments about the importance of deterministic responses are applied only in deciding which responses are sufficiently adverse to warrant consideration in setting protection standards. 

For the purpose of developing a risk-based hazardous waste classification system, prevention of deterministic responses should be of concern only for hazardous chemicals, but not for radionuclides. Deterministic responses from exposure to radionuclides can be ignored because radiation dose limits for the public intended to limit the occurrence of stochastic responses are sufficiently low that the doses in any organ or tissue would be well below the thresholds for deterministic responses (see Section 3.2.2.1). 

1 Incidence. In the first option, the common measure of stochastic response from exposure to radionuclides and hazardous chemicals would be incidence, without any modifications to account for such factors as differences in lethality fractions for responses in different organs or tissues or expected years of life lost per fatality. Such modifications are intended to represent differences in the severity of different stochastic responses. 

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