Carcinogens are mutagens: a simple test system combining liver homogenates for activation and bacteria for detection.
Level 5 - mechanism / opinion, no new human data
In vitro bench laboratory study
PubMed 4151811 · doi:10.1073/pnas.70.8.2281
What was done
An in vitro bacterial mutation test system (the Ames test) was developed to detect carcinogens as mutagens. The assay incubated Salmonella histidine mutants, rat or human liver homogenates (to provide mammalian metabolic activation), and a TPNH-generating system together on a single petri plate, evaluating 18 known carcinogens including aflatoxin B1, benzo[a]pyrene, acetylaminofluorene, benzidine, and dimethylamino-trans-stilbene.
What was found
All 18 tested carcinogens were activated by liver homogenates to form potent frameshift mutagens. For the most active compounds, mutagenicity was detectable at quantities as low as a few nanograms. Specific mutation counts or quantitative dose-response values for each individual agent were not provided in the abstract.
Why it matters
This seminal study established a rapid, inexpensive, and sensitive screening assay linking chemical carcinogenesis to somatic mutagenesis by combining mammalian metabolic activation with bacterial detection.
Limits
The study is an in vitro microbial assay and does not directly measure mammalian or human in vivo carcinogenesis, tissue distribution, or complex non-mutagenic carcinogenic pathways. Quantitative mutation rates and performance on non-carcinogenic negative controls are not detailed in the abstract.
Cited by
- supports Bruce Ames developed the Ames test to identify chemical carcinogens.