title: Toxicity and carcinogenicity study in F344 rats following 2 years of whole-body exposure to naphthalene vapors.
abstract: The toxicologic and carcinogenic potential of naphthalene was studied by exposing groups of 49 male and 49 female F344 rats to atmospheres containing 0, 10, 30, or 60 ppm of the chemical for 6 h daily, 5 days/wk for 2 yr. Mean body weights of exposed groups of male rats were less than for the control group throughout most of the study. Mean body weights of exposed female rats were generally similar to those of controls. Survival of exposed and control rats was similar. Under the conditions of this 2-yr inhalation study, naphthalene was carcinogenic to male and female F344/N rats, causing increased incidences of respiratory epithelial adenoma (males: control, 0%; low dose, 12%, mid dose, 17%; high dose, 31%; females: 0%; 0%; 8%; 4%) and olfactory epithelial neuroblastoma (males: control, 0%; low dose, 0%; mid dose, 8%; high dose, 6%; females: 0; 4%; 6%; 24%) of the nose. In both sexes of rats, exposure to naphthalene also caused significant increases in the incidences of nasal lesions including hyperplasia, atrophy, chronic inflammation, and hyaline degeneration of the olfactory epithelium and hyperplasia; squamous metaplasia, hyaline degeneration, and goblet-cell hyperplasia of the respiratory epithelium; and glandular hyperplasia and squamous metaplasia.
authors.affiliation: National Institute of Environmental Health Sciences, National Institutes of Health, PO Box 12233, Research Triangle Park, NC 27709, USA. abdok@niehs.nih.gov
authors.forename: K M
authors.initials: KM
authors.lastname: Abdo
authors.forename: S
authors.initials: S
authors.lastname: Grumbein
authors.forename: B J
authors.initials: BJ
authors.lastname: Chou
authors.forename: R
authors.initials: R
authors.lastname: Herbert
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000502:physiology; D005260:Female; D008168:Lung / Q000187:drug effects / Q000473:pathology; D008297:Male; D009281:Naphthalenes / Q000008:administration & dosage / Q000378:metabolism / Q000633:toxicity*; D009666:Nose / Q000187:drug effects / Q000473:pathology; D009669:Nose Neoplasms / Q000139:chemically induced* / Q000473:pathology; D051381:Rats; D011916:Rats, Inbred F344; D013045:Species Specificity; D014835:Volatilization
chemical_list: D009281:Naphthalenes; C007229:decalin; D003577:Cytochrome P-450 Enzyme System