US EPA

3064613 

Technical Report 

Inhibition of testicular DNA synthesis by chemical mutagens and carcinogens. Preliminary results in the validation of a noval short term test 

Seiler, JP 

1977 

PESTAB/77/2432 

Res 

4 

PESTAB. Measurement of the inhibition of testicular DNA synthesis by chemical carcinogens and mutagens in male mice has been proposed as a screening test (Friedman-Staub assay). A series of experiments was initiated to validate this test system; results obtained with 100 chemicals tested are presented. A first group of chemicals comprised known mutagens and carcinogens, a second group comprised compounds (especially pesticides) which had previously been tested and had failed to display such activity, and a third group comprised some anilines of unknown properties. At least 86% of the compounds previously known as carcinogens and/or mutagens gave positive results in the test, whereas only 10% of the compounds previously determined to be non-carcinogenic and non-mutagenic significantly depressed DNA synthetic activity. Most of the carcinogens and mutagens detected in this test gave negative results in the Ames test. Positive results in this test were obtained with dichlofluanid, which had been previously reported to be free from carcinogenic activity. The explanation and significance of this finding remain to be determined. Large amounts of the chemicals tested must be given to the animals to elicit a response. The test will not detect mutagenic or carcinogenic activity of an impurity within an otherwise inactive compound.