Molecular activity Subject index

PbB has long been used as the standard index of dose in estimating dose-effect and dose-response relationships. Some would argue that it is perhaps less valid than certain other measurements which reflect in quantitative fashion the bioavailable fraction of PbB, much as erythrocyte cholinesterase inhibition reflects the toxic impact of exposure to organophosphate insecticides. Indeed, it has been reported that inhibition of erythrocyte membrane Na, K-ATPase activity is better correlated with lead toxicity than erythrocyte lead concentration (Raghavan ei al, 1981). This was attributed to the fact that the subjects had variable concentrations of a low molecular weight lead binding protein which influenced the bioavailable fraction of PbB. It is possible that EP reflects bioavailable lead in a similar fashion. 

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