REPRODUCTIVE TOXICITY STUDY OF CLARIFIED SLURRY OIL IN THE RAT

Clarified slurry oil (CSO, CAS #64741-62-4; also termed carbon black o il), a residual product from the fluidized catalytic cracker in petrol eum refining, has the potential to be absorbed through the skin. The r eproductive toxicity of CSO in male and female rats was evaluated by t he topical route of exposure. CSO was administered dermally to male ra ts at dosages of 0 (vehicle), 0.1, 1, 10, 50, and 250 mg/kg/day for 70 days before a cohabitation period with untreated female rats. CSO was administered also to female rats at the same dosages for 14 days prio r to a 7-day cohabitation period and continuing until Day 0 of gestati on (day spermatozoa was present in a smear of the vaginal contents or a copulatory plug was observed in situ). The dosage volume in both exp eriments was 1 ml/kg, adjusted on each day of dosage based on individu al body weights recorded immediately before application of CSO. Under the conditions of these experiments, the paternal no-observable-advers e-effect-level (NOAEL) for CSO administered dermally was 1 mg/kg/day. The 10, 50, and 250 mg/kg/day dosages of CSO caused body weight losses and/or decreased body weight gains and reduced feed consumption. The 50- and 250-mg/kg/day dosages also caused adverse clinical effects. No mating, fertility, or testicular end points in male rats were affecte d by the highest dosages tested; therefore, the reproductive NOAEL for male rats is >250 mg/kg/day. The maternal NOAEL for CSO administered dermally was 10 mg/kg/day. The 50-and 250-mg/kg/day dosages of CSO red uced body weight gains; 250 mg/kg/day also reduced feed consumption. T here were no adverse effects on gonadal function, estrous cycles, mati ng behavior, conception rates, or reproductive organ weights; therefor e, the reproductive NOAEL for female rats administered CSO dermally is at least 250 mg/kg/day.