Initial National Cancer Institute studies on mutagenesis as a prescreen for chemical carcinogens: an appraisal.

The efficacy of several in vitro and in vivo assays to detect carcinogens from a list of compounds was evaluated. Salmonella and polymerase A-deficient Escherichia coli in vitro were the most effective systems studied. Together they detected 82% of the organic carcinogens tested. Potential prescreening systems, which were thought to be currently insufficiently sensitive for the routine screening of potential carcinogens, included a) the development of resistance to thymidine overloading, methotrexate, and cytosine arabinoside by L5178y cells, b) Saccharomyces cerevisiae D3, c) the intraperitoneal host-mediated assay, and d) thymidine uptake as a reflection of DNA repair.