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Negative and positive control ranges in the bacterial reverse mutation test: JEMS/BMS collaborative study.

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This study established proficiency indicators for the bacterial reverse mutation test by analyzing control data from 30 laboratories over four years. Results show consistent and predictable control counts, aiding in test validation.

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Area of Science:

  • Genotoxicology
  • Microbiology
  • Environmental Science

Background:

  • The bacterial reverse mutation test (Ames test) is a standard method for assessing mutagenicity.
  • Standardized proficiency indicators are crucial for reliable genotoxicity testing across laboratories.

Purpose of the Study:

  • To identify and validate proficiency indicators for the bacterial reverse mutation test using a preincubation procedure.
  • To establish acceptance criteria for laboratory performance in mutagenicity assays.

Main Methods:

  • A multi-laboratory study involving approximately 30 labs from 2013-2016.
  • Collection and statistical analysis of negative and positive control data for standard bacterial strains (Salmonella and E. coli) with and without S9 mix.
  • Evaluation of dose-response curves for positive control articles.

Main Results:

  • The majority of control counts fell within the mean ±2 standard deviation range.
  • Negative control counts followed normal or Poisson distributions, while positive control counts were approximately normal.
  • Control count distributions remained stable over the four-year study period.
  • Dose-response relationships were consistently linear or exponential up to recommended doses.

Conclusions:

  • The study provides valuable data for defining acceptance criteria for the bacterial reverse mutation test.
  • The findings support the estimation of laboratory proficiency in conducting mutagenicity assays.
  • Consistent control data suggests the reliability of the bacterial reverse mutation test when performed under standardized conditions.