A Mutagen Assessment Program

One of the two major tasks of the Committee is to determine how data from diverse test systems can best be used to assess mutagenic damage to human germ cells. 

Chapter 9 details a program for this purpose, but it is summarized here. The proposed program has five levels  

Screening of many chemicals with short-term tests. 

To the extent feasible, this should include all chemicals to which humans are routinely exposed. New chemicals should be tested before they are put into large-scale production. In most cases, the outcomes of such tests will be sufficient to support industrial or governmental control. 

Classification of chemicals by mutagenic potency in individual test systems. It is not feasible to be fully quantitative, because there are inconsistencies among tests, but a rough classification based on relative potency is useful for decision-making when a simple, all-or-none classification (i.e., mutagenic or nonmutagenic) is insufficient. 

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The success of a mutagen assessment program depends strongly on the efficacy of the screening system, for most of the decisions regarding individual chemicals must be made on the basis of short-term screening tests. The criteria for choosing test systems are discussed in Chapter 6. On the basis of these criteria, the Committee has selected a set of tests, listed as "principal shortterm tests" in Table 9-1. Confirmatory rodent tests and supplementary tests are also listed. 

An example of one of the output screens from APEX, from the analysis of a set of mutagens, is shown in Fig. 9.25. Biophores found to be associated with the active set, shown in the box at centre top, are listed in the top right-hand comer of the screen. One of these biophores has been selected for display in the bottom window, and three members of the active set (indicated by highlighting in the active list) are shown superimposed on the biophore. Various information about the biophores, including an assessment of their significance by cross-validation, is easily extracted from the program. 

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