Five cysteinyl adducts (including one with multiple isomeric forms) of hemoglobin (Hb) and albumin (Alb) have been characterized in the blood of Sprague-Dawley rats following administration of pentachlorophenol (PCP). Three of these adducts were formed by multiple substitution reactions of tetrachloro-1, 4-benzoquinone (Cl4-1, 4-BQ) and its products, and two arose from reactions of tetrachloro-1, 4-benzosemiquinone (Cl4-1, 4-SQ) and ...