Long-term carcinogenicity bioassays on styrene administered by inhalation, ingestion and injection and styrene oxide administered by ingestion in Sprague-Dawley rats, and para-methylstyrene administered by ingestion in Sprague-Dawley rats and Swiss mice.
Styrene was administered to Sprague-Dawley rats by inhalation (300, 100, 50, 25, 10 and 0 ppm, 4 hours daily, 5 days weekly, for 52 weeks); by gavage (250, 50 and 0 mg/kg b.w. in olive oil, once daily, 4-5 days weekly, for 52 weeks), by intraperitoneal injection (50 and 0 mg in olive oil, four times at 2-month intervals), by subcutaneous injection (50 and 0 mg in olive oil, once). Styrene oxide was administered to Sprague-Dawley rats by gavage as styrene (250, 50 and 0 mg/kg b.w. in olive oil, once daily, 4-5 days weekly, for 52 weeks). The animals were kept under observation until spontaneous death. Para-methylstyrene was also administered by gavage to Sprague-Dawley rats at 500, 250, 50, 10 and 0 mg/kg b.w., and to Swiss mice at 250, 50, 10 and 0 mg/kg b.w., in olive oil, once daily, 5 days weekly, for 108 weeks and 78 weeks, respectively. The study was terminated when the survival rate reached 50% in at least one experimental group. Styrene, when given by inhalation, was found to cause an increase in total (benign and malignant) and malignant mammary tumors. Styrene oxide produced a high incidence of tumors in the forestomach (papillomas, acanthomas, and in situ and invasive squamous cell carcinomas). Para-methylstyrene was not shown to be carcinogenic.
Conti
B
B
Institute of Oncology F. Addarii, Bologna, Italy.
Maltoni
C
C
Perino
G
G
Ciliberti
A
A
D000280:Administration, Inhalation; D000284:Administration, Oral; D000818:Animals; D001681:Biological Assay; D004852:Epoxy Compounds / Q000008:administration & dosage / Q000633:toxicity*; D004988:Ethers, Cyclic / Q000633:toxicity*; D007275:Injections, Intravenous; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced; D051379:Mice; D051381:Rats; D011919:Rats, Inbred Strains; D013274:Stomach Neoplasms / Q000139:chemically induced; D020058:Styrene; D013343:Styrenes / Q000008:administration & dosage / Q000032:analysis / Q000633:toxicity*
D004852:Epoxy Compounds; D004988:Ethers, Cyclic; D013343:Styrenes; C027142:vinyltoluene; D020058:Styrene; C013690:styrene oxide