Risk Index for Mixtures of Substances That Cause Stochastic Effects Carcinogens

1 Risk index for mixtures of substances that cause stochastic effects (carcinogens). The risk index for mixtures of substances that cause stochastic effects (radionuclides and chemical carcinogens) takes into account the risk in all organs or tissues, and it assumes that the risk in any organ is independent of the risk in all other organs. The risk index for mixtures of substances causing stochastic effects can be represented as  

3 Use of the composite risk index in classifying waste. Given the risk indexes for mixtures of substances causing stochastic or deterministic effects calculated using Equations 1.5 and 1.6, respectively, the composite risk index for all hazardous substances is calculated using Equation 1.4. This procedure assumes that induction of stochastic effects is independent of exposures to substances causing deterministic effects, and vice versa. 

As emphasized in Section 1.1, the recommended approach to classifying waste does not provide a basis for establishing waste acceptance criteria at specific disposal sites. NCRP expects, however, that waste classified as exempt or low-hazard in accordance with its recommendations should be acceptable for disposal in the associated type of disposal facility at well-chosen sites. 

The recommended risk-based waste classification system has important implications in three areas (1) the resulting classification of existing radioactive and hazardous chemical wastes, (2) subclassification of the basic waste classes, and (3) changes in existing laws and regulations that would be required to implement such a classification system. 

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