Effects of the water-soluble carcinogen 4-nitroquinoline N-oxide on hamster lingual mucosa

The water-soluble carcinogen 4-nitroquinoline N-oxide (4NQO) was painted onto hamster ventral lingual mucosa twice weekly for up to 20 weeks. No neoplasms developed during this period. The promoting agent croton oil was applied to the treated areas in an attempt to determine whether initiation had occurred. During the following 6 months, one animal developed a papilloma and three animals showed areas of epithelial atypia in the treated mucosa. No malignant neoplasms were seen. Despite its efficiency in producing intraoral neoplasms in the rat, 4NQO would appear to be a poor choice in the hamster.