Mammalian cell culture mutagenicity and carcinogenicity testing of dimethyl sulfoxide extracts of flame retardant‐treated cotton fabrics

Abstract

Dimethyl sulfoxide extracts of flame retardant‐treated cotton fabrics were tested for ability to mutate and transform mammalian cells in culture. Fabrics were treated with tetrakis(hydroxymethyl)phosphonium chloride (THPC) and tetrakis(hydroxymethyl)‐phosphonium sulfate (THPS). Extracts were prepared at the precondensate stage of flame retardant processing and after ammonia neutralization (THPOH‐NH ₃ ). Uncon‐centrated or 10‐fold concentrated extracts were tested as 0.5 or 1% solutions in cell culture medium. All extracts were mutagenic to V79 hamster lung cells (conversion to ouabain resistance) with or without addition of rat liver microsomes (S9). Up to 84 mutant colonies per 10 ⁶ surviving cells were found with THPS fabric extracts, whereas up to 113 were obtained with THPC fabric extracts. Extracts were also able to transform mammalian cells, as shown in two different assays. Transformation of BHK cells, as measured by colony formation in soft agar, increased more than 20‐fold with THPC extracts, but less than 2‐fold with THPS extracts. Both the THPC and THPS extracts induced 3T3 cell transformation with linear dose‐response. The number of foci of transformed cells per 10 ⁵ survivors was 10–100 times that in the solvent control. Greater numbers of transformed foci were obtained after treatment at the highest doses tested than after treatment with the positive control compounds, benzo[a] pyrene and N‐methyl‐N‐nitro‐N‐nitrosoguanidine.