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

A large-scale study was conducted by multiple laboratories affiliated with the Japanese Environmental Mutagen Society and the Bacterial Mutagenicity Study Group to investigate possible proficiency indicators for the bacterial reverse mutation test with a preincubation procedure. Approximately 30 laboratories generated negative and positive control count data and dose-response curves of the positive control articles for the bacterial reverse mutation test, with assays conducted annually from 2013 to 2016. Overall, the majority of the negative and positive control counts for Typhimurium strains TA100, TA1535, TA98, and TA1537, and strain WP2, with and without S9 mix, were within the range of the means ±2× standard deviation.