Mutagenic potential of binary mixtures of nitro-polychlorinated dibenzo-p-dioxins and related compounds.
The mutagenic potential of binary mixtures of nitro-polychlorinated dibenzo-p-dioxins and other environmentally related compounds was determined using Salmonella typhimurium strain TA98 in the standard plate incorporation assay. Samples tested included binary mixtures of 4-nitro-4'-chlorobiphenyl with 6-nitro-4,2',3',4',5'-pentachlorobiphenyl, 4-nitrobenzo-p-dioxin with 4-nitro-2,3,8-trichlorodibenzo-p-dioxin, and benzo[a]pyrene with either nitropentachlorobiphenyl or nitrotrichlorodibenzo-p-dioxin. Inhibition was the primary interaction observed for the mixtures of polyhalogenated dioxins or biphenyls with the direct-acting mutagens nitrodibenzo-p-dioxin or nitrochlorobiphenyl. At the highest dose tested, nitrotrichlorodibenzo-p-dioxin inhibited the bacterial mutagenicity of nitrodibenzo-p-dioxin by almost 50%, while pentachlorobiphenyl inhibited the mutagenicity of nitrobiphenyl by 34%. Conversely, synergism was the primary interaction observed for mixtures of halogenated aromatics with the promutagen benzo[a]pyrene. The addition of nitrotrichlorodioxin to benzo[a]pyrene enhanced the mutagenicity of the latter compound by as much as 70%, while the mutagenic potential of a mixture of benzo[a]pyrene and nitropentachlorobiphenyl was approximately 50% greater than the mutagenicity of benzo[a]pyrene alone. In summary, mixtures of nonmutagenic nitropolyhalogenated biphenyls or dibenzo-p-dioxins appear to inhibit the mutagenicity of direct-acting mutagens, while these same compounds seem to enhance the mutagenic potential of the promutagen benzo[a]pyrene.
Donnelly
K C
KC
Department of Soil and Crop Sciences, Texas A&M University, College Station 77843.
Brown
K W
KW
Estiri
M
M
Jones
D H
DH
Safe
S
S
D000818:Animals; D001564:Benzo(a)pyrene; D004147:Dioxins / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004785:Environmental Pollutants / Q000633:toxicity*; D009153:Mutagens; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives / Q000633:toxicity*; D051381:Rats
D004147:Dioxins; D004785:Environmental Pollutants; D009153:Mutagens; D000072317:Polychlorinated Dibenzodioxins; D001564:Benzo(a)pyrene