Results of NTP-sponsored mouse cytogenetic studies on 1,3-butadiene, isoprene, and chloroprene.
Studies were conducted to determine the cytotoxic and cytogenetic effects of 1,3-butadiene and two structural analogs, chloroprene and isoprene, in the bone marrow cells of B6C3F1 mice exposed to the chemicals by inhalation. In one study, animals were exposed to 1,3-butadiene concentrations of 6.25, 62.5, or 625 ppm 6 hr/day on 10 exposure days and in the second study, to the same concentrations on weekdays for 13 weeks. Chloroprene and isoprene treatments involved 6 hr/day exposures on 12 exposure days at concentrations of 0, 12, 32, 80, and 200 ppm for chloroprene and 0, 438, 1750, and 7000 ppm for isoprene. In the 10-day study, 1,3-butadiene induced significant increases in sister chromatid exchange (SCE) at 6.25 ppm, micronuclei at 62.5 ppm, and chromosomal aberrations at 625 ppm. In the 13-week study, the frequency of micronucleated normochromatic erythrocytes in the peripheral blood was significantly elevated in all exposure groups including the 6.25-ppm group. Isoprene induced both SCE and micronuclei, whereas chloroprene gave negative results for all cytogenetic end points assessed in bone marrow cells.
Cellular and Genetic Toxicology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709.
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D000818:Animals; D001853:Bone Marrow / Q000187:drug effects; D002070:Butadienes / Q000494:pharmacology*; D002737:Chloroprene / Q000494:pharmacology*; D002869:Chromosome Aberrations; D045782:Hemiterpenes; D008297:Male; D051379:Mice; D048629:Micronuclei, Chromosome-Defective / Q000187:drug effects; D009152:Mutagenicity Tests; D009153:Mutagens; D010420:Pentanes; D012854:Sister Chromatid Exchange / Q000187:drug effects
D002070:Butadienes; D045782:Hemiterpenes; D009153:Mutagens; D010420:Pentanes; C005059:isoprene; D002737:Chloroprene; C031763:1,3-butadiene