Mutagenic and clastogenic properties of 3-chloro-4-(dichloromethyl)-5-hydroxy-2 (5H)-furanone: a potent bacterial mutagen in drinking water.

3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) was found to be a direct-acting mutagen in the Ames test for strains TA1535, TA1538, TA92, TA97, TA98, TA100 and TA102. The highest mutagenic response (approximately 13,000 revertants/nmol) was seen in strain TA100. The TA100 response was six- to tenfold higher than in TA98, TA97, and TA102, and 100- to 500-fold higher than in TA1535, TA92, and TA1538. The addition of a 9,000 x g supernatant fraction (S-9) from livers of polychlorinated biphenyl-treated rats, along with cofactors for NADPH generation, resulted in a 90% reduction in the TA100 mutagenicity. MX induced chromosomal aberrations in Chinese hamster ovary cells after 6-8 hr exposure without S-9 at a dose as low as 4 micrograms/ml, and after 2 hr exposure with S-9 at a dose of 75 micrograms/ml. The oral dose of MX lethal to 50% (LD50) in Swiss-Webster mice was determined to be 128 mg/kg. MX did not induce micronuclei in mouse bone marrow when administered by oral gavage at doses up to 70% of the LD50.