The Hela DNA-synthesis inhibition test as a rapid screen for mutagenic carcinogens

90 agents have been tested in the HeLa DNA-synthesis inhibition test. This test detects strong mutagens and carcinogens except when difficulties with metabolic activation are encountered. Weaker DNA-damaging agents are generally positive in the test but require relatively high concentrations (greater than 1 mM). Very weak agents, such as saccharin, are not positive. Only 1 false positive has been encountered and the dose response for it (cytochalasin B) is atypical. The test does not seem suitable for complex mixtures, probably because ingredients that do not damage DNA but inhibit DNA synthesis by another mechanism can mask the action of a DNA-damaging agent. Inhibition of DNA synthesis in HeLa and other mammalian cells is best used as a rapid and inexpensive screening procedure to detect relatively strong mutagenic carcinogens.