Use of the dominant-lethal test to detect genetic activity of environmental chemicals.

Potential genetic hazards due to drugs and chemical pollutants are now generally recognized. Such recognition has been paralleled by the recent development of appropriate sensitive, and practical in vivo mammalian methods for detecting and measuring mutagenic effects due to chemicals (1,2). These methods have a high degree of presumptive human relevance and include in vivo cytogenetics, the host-mediated assay, and the dominant-lethal assay; submammalian systems are generally considered' to yield -data of ancillary value (3). An expert HEW committee has recently recommended that drugs, pesticides, food additives and other synthetic chemicals be tested for mutagenicity in mammalian systems prior to their use or registration (1). Dominant-lethal mutations have been used as convenient indicators of major genetic damage for measuring the effects of x-ray and of mutagenic chemicals in mammals. Such data may be appropriately extrapolated to man, especially as many recognizable human autosomal traits are due to dominant mutations (4). The genetic basis for dominant lethality