During the past eight to ten years, in vitro test systems have evolved into the first line of attack in determining the toxic effects of environmental mutagens and carcinogens. One of the more significant of the toxic effects evaluated by these tests is geno-toxicity, or adverse effects on chromosomal DNA. Using information obtained from mammalian in vitro test systems, we have developed several toxicity tests which measure geno-toxicity for fish cells in vitro. The first of these tests to be developed was the inhibition of cell division or blockade of mitosis. This test shows that cells can survive exposure to mutagens/carcinogens, but that cell division is blocked. The second test measures perturbations of the DNA replication process and is expressed as exchanges of nucleic acid between chromatids during mitosis. This test, known as sister chromatid exchange (SCE), is frequently used in human and mammalian systems to detect exposure to genotoxic agents. The third procedure adapted to in vitro fish cell testing is the anaphase aberration test. This procedure shows overt abnormalities which develop during mitosis and appears to be relatively sensitive to low doses of toxic compounds.

Each of these test procedures is relatively easy to perform, require only one to four days for results, and each appears quite sensitive to the effects of known noxious chemicals. At this time, every class of genotoxic chemical tested has produced a positive response in these systems and was shown to be capable of producing overt forward mutations in some of the fish cells employed.

*Research supported by a grant (NA80RAD00053) from the Office of Marine Pollution Assessment, National Oceanic and Atmospheric Administration, U. S. Department of Commerce.