Biochemical Approaches to Monitoring Human Populations for Germinal Mutation Rates: II. Enzyme Deficiency Variants as a Component of the Estimated Genetic Risk

Abstract

The ultimate function of toxicology screening systems is to provide an accurate estimate of the human health risk associated with exposure to potentially hazardous agents. A number of test systems, with varying capabilities, have been developed and it has been proposed that combinations of several of these systems be utilized in a tier approach to estimating risk. The shortcomings of the various components of the tier system, including differences in metabolic pathways, target tissue specificity, cell replication, etc., have been discussed [1]. An additional problem is the lack of relevant data from human populations which may be used as a reference for extrapolation. That is, it is difficult to estimate human health risk utilizing data obtained in test systems in the absence of at least some data from a limited number of studies relating the nature and extent of exposure, the frequency of events induced and the associated increase in health costs in a human population. The absence of a data base is most apparent for germinal mutations, where except for genetic damage involving structural or numerical chromosomal abberations [2–4], the data on the frequency of possible mutagenic events, either spontaneous or induced, are very limited. Most previous estimates of the frequency of mutational events in human populations have utilized either the population characteristic or sentinel phenotype approach [5–7]. Recently, electrophoretic techniques have been developed which can be used to obtain data relevant to the estimation of both the background and induced mutation rate in human populations [8–10]. The current status of these electrophoretic methodologies is described by Neel et al., in a companion paper in this symposium [11].