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An interlaboratory study of an EPA/Ames/Salmonella test protocol.
Mutation Research
|June 1, 1987
Summary
This Ames test study found significant variability in results between labs and within labs. High variation means chemicals must be much more mutagenic to show a significant difference.
Area of Science:
- Environmental toxicology
- Genotoxicity testing
Background:
- The Ames test is a standard method for assessing chemical mutagenicity.
- Interlaboratory studies are crucial for validating toxicological protocols.
Purpose of the Study:
- To evaluate the reproducibility of an EPA standard protocol for the Ames test.
- To assess intralaboratory and interlaboratory variability in mutagenicity testing.
Main Methods:
- Seven laboratories participated, using Salmonella typhimurium strains TA98 and TA100.
- Three metabolic activation levels (0%, 2%, 10% S9) were employed.
- Six pure chemicals and two complex mixtures were tested as coded unknowns.
Main Results:
- Qualitative agreement with published data was lower than in a previous study using individual lab protocols.
- Substantial intralaboratory and interlaboratory variations were observed in quantitative data.
- Variations of an order of magnitude or more (CV of 115%) were seen in mutagenic response measurements.
Conclusions:
- Significant variability necessitates large differences (over 10-fold) in mutagenicity for statistically significant detection.
- These variations must be considered when interpreting Ames/Salmonella test data.
- The EPA standard protocol's reproducibility requires further investigation.