Clastogenicity of diepoxybutane in bone marrow cells and male germ cells of mice

The bifunctional metabolite of 1,3-butadiene, 1,2:3,4-diepoxybutane(DEB), was tested in the mouse bone marrow micronucleus assayand in male mouse germ cell tests, namely the analysis of firstcleavage divisions and the dominant lethal assay. All experimentswere performed with single intraperitoneal treatment of theanimals. In the micronucleus test, DEB doses of 4.5, 9.0, 18.0and 36.0 mg/ kg body weight were tested at a sampling intervalof 24 h for bone marrow. The dose response for the inductionof micronuclei in polychromatic erythrocytes was linear withthe lowest effective dose of 9.0 mg/kg body weight No sensitivitydifference was observed between male and female mice. The cytogeneticanalysis of first cleavage division chromosomes was performedafter treatment of male mice with 17, 26, 34, 43 and 52 mg/kgbody weight of DEB and mating the males to hormonally stimulatedfemales on days 7, 14, 21 and 28 after treatment The two higherdoses caused general toxicity evidenced by the poor mating behaviorof the males. Only 13 and 20% of the mated females were fertilizedon day 7 after treatment of the males with 43 and 52 mg/kg bodyweight of DEB, respectively. An increased number of unfertilizedoocytes was obtained from fertilized females on day 7 aftertreatment of the males with 34 mg/kg body weight of DEB. Witha dose of 26 mg/kg body weight, it was demonstrated that chromosomalaberrations were only induced in spermatozoa (mating on day7 after treatment) while spermatids (mating on days 14 and 21)and spermatocytes (mating on day 28) were not susceptible tothe clastogenic effect of DEB. The response in spermatozoa inthe dose range 17–34 mg/kg body weight was linear up to26 mg/kg body weight and reached a plateau thereafter. The resultsof the dominant lethal experiments performed in the dose range18–54 mg/kg body weight gave results similar to the cytogeneticstudy. With the highest dose tested, the toxicity and cytotoxicityduring the first 8 mating days after treatment dramaticallyreduced the number of pregnant females and, consequently, thetotal implantations, so that no significant dominant lethaleffect could be assessed. During mating days 9–12 (treatedlate spermatids), a significant dominant lethal effect was observed.With the two lower doses (18 and 36 mg/kg body weight), thedominant lethal effect was restricted to spermatozoa. The goodcorrelation of the chromosomal aberrations with dominant lethalmutations confirms the chromosomal origin of dominant lethaleffects. The clastogenic effect of DEB in somatic cells andin germ cells of mice was of the same order of magnitude. ³To whom correspondence should be addressed