Gaseous butadiene (BUT) was mutagenic towards S. typhimurium strain TA 1530 when the incubation mixture was supplemented with a NADPH-fortified rat liver microsomal preparation; mutagenicity increased with the dose. A significant mutagenic effect was similarly observed when the petri dishes, containing the bacteria but no metabolic activation system, were incubated in the presence of butadiene, in a desiccator in which plates containing the S-9 rat liver fraction had been placed. This indirect mutagenic effect was attributed to the formation, by the S-9 mix, of volatile intermediate(s) that migrated and induced mutations in neighbouring bacteria.
De Meester, C., Poncelet, F., Roberfroid, M., & Mercier, M. (1980). The mutagenicity of butadiene towards Salmonella typhimurium. Toxicology Letters, 6(3), 125-130. https://hdl.handle.net/2078.5/70789 (Original work published 1980)