Occupational exposures to
1,3-butadiene or
isoprene occur through their use in the manufacture of rubber and other related
polymer products. The purpose of this study was to determine if
butadiene or
isoprene administration would result in the formation of adducts with blood
hemoglobin (Hb), and if such adducts can be used as a measure of previous exposure(s). Male B6C3F1 mice and male Sprague-Dawley rats were injected intraperitoneally with 1, 10, 100, or 1000 mumol [14C]
butadiene or 0.3, 3.0, 300, 1000, or 3000 mumol [14C]
isoprene per kilogram
body weight. Animals were killed 24 hr later.
Globin was isolated from blood samples and was analyzed for 14C by liquid scintillation spectroscopy. Hb adduct formation was linearly related to administered doses up to 100 mumol [14C]
butadiene or 500 mumol [14C]
isoprene per kilogram
body weight for mice and rats, respectively. For [14C]
butadiene, the efficiency of Hb adduct formation in mice and rats within the linear response range was 0.177 +/- 0.003 and 0.407 +/- 0.019 (pmol of 14C-adducts/mg
globin)/(mumol of retained [14C]
butadiene/kg body wt), respectively (mean +/- SE; n = 18). For [14C]
isoprene, these values for mice and rats were 0.158 +/- 0.035 and 0.079 +/- 0.016 (pmol of 14C-adducts/mg
globin)/(mumol of retained [14C]
isoprene/kg body wt), respectively (mean +/- SE; n = 12). Hb adducts also accumulated linearly after repeated daily administration of 100 mumol [14C]
butadiene or 500 mumol [14C]
isoprene per kilogram body wt to mice and rats, respectively, for 3 days. [14C]
Butadiene-derived Hb adducts in blood showed lifetimes of approximately 24 and approximately 65 days for mice and rats, respectively, which correlate with the reported lifetimes for red blood cells in these rodent species. Thus, levels of
butadiene- or
isoprene-derived adducts on Hb in circulating blood may be a useful measure of prior repeated exposures to these compounds.