GENDER AND SPECIES-DIFFERENCES IN THE METABOLISM OF 1,3-BUTADIENE TO BUTADIENE MONOEPOXIDE AND BUTADIENE DIEPOXIDE IN RODENTS FOLLOWING LOW-LEVEL INHALATION EXPOSURES

Levels of butadiene monoepoxide (BDO) and butadiene diepoxide (BDO2) w ere compared in tissues of male Sprague-Dawley rats and male B6C3F(1) mice and in tissues of male and female Sprague-Dawley rats following i nhalation exposures to 62.5 ppm 1,3-butadiene (ED). In male rats, BDO2 levels were highest in blood and were present at a concentration of o nly 5 +/- 1 pmol/g. Following a 6-h exposure, the concentration of BDO 2 in the blood, femurs, lung and fat of female rats was 3 to 7-fold th at of male rats. Levels of BDO were similar in tissues of female and m ale rats. Generally, levels of BDO were approximately 3 to 8-fold grea ter in mouse tissues as compared with rat tissues following 4-h exposu res to ED. In blood, 204 +/- 15 pmol/g BDO2 was detected in male mice, while in rats, blood BDO2 levels were 5 +/- 1 pmol/g. This study show s marked species differences in tissue levels of BD epoxides, particul arly BDO2, in rats and mice, and is the first to show gender differenc es in ED metabolism.