Toxicology and carcinogenesis studies of cresols (CAS No. 1319-77-3) in male F344/N rats and female B6C3F1 mice (feed studies).

Background: Cresols are petroleum byproducts that are used to make resins, solvents, disinfectants, fragrances, and wood preservatives. We performed tests to determine if cresols caused cancer in rats or mice.

Methods: We fed groups of 50 male rats and female mice cresols mixed into their feed. Male rats were given concentrations of 1,500, 5,000, or 15,000 parts per million (ppm) of cresols in their feed, and female mice were given concentrations of 1,000, 3,000, or 10,000 ppm. Similar groups of 50 animals were given undosed feed as the control groups. Tissues from more than 40 sites were examined for every animal.

Results: The groups fed the highest concentration of cresols weighed less than their control groups. A few rare tumors of the kidney were seen in exposed male rats, and the rate of tumors of the forestomach was increased in exposed female mice. Male rats and female mice given cresols had hyperplasia of the epithelium of the nose. Exposed male rats also had hyperplasia of the kidney, and female mice had hyperplasia of the lung and degeneration of the thyroid gland.

Conclusions: We conclude that the occurrence of forestomach papillomas in female mice was caused by exposure to cresols. The occurrence of a few kidney tumors in male rats may have been related to exposure to cresols.