Point of Departure Index

A scientifically more appropriate method of addition is summing the exposures of each compound expressed as a fraction of their respective POD instead of the ADIs or RfDs. These POD fractions (PODF) are reciprocals of the individual MOEs (see Section 10.5.1.5) of each compound. This approach sums the exposures to the compounds in terms of their relative potencies. In this example, the BMDio (Table 10.2) was used as POD  

The PODI can be converted into a risk cup unit by multiplying by an appropriate group AF. For example, a group AF of 100 would result in a combined risk of 0.84 risk units. 

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The approaches discussed are the hazard index (HI) (Section 10.5.1.1) and the weight-of-evidence (WOE) modification to the HI (Section 10.5.1.2), the point of departure index (PODl) (Section 10.5.1.3), toxicity equivalency factors (TEFs) (Section 10.5.1.4), the margin of exposure (MOE) procedures (Section 10.5.1.5), and the cumulative risk index (CRl) method (Section 10.5.1.6). 

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