Technical Report
Nasal Tumours in Rats after Severe Injury to the Nasal Mucosa and Exposure to Formaldehyde Vapour: Preliminary Results
Feron, VJ; Immel, HR; Wilmer, JWGM; Woutersen, RA; Zwart, A
Feron, VJ; Immel, HR; Wilmer, JWGM; Woutersen, RA; Zwart, A
NIOSH/00176121
A 28 month study was conducted during which 720 male albino-Wistar-rats inhaled formaldehyde (50000) at 0.1, 1.0 or 10 parts per million (ppm). Bilateral intranasal electrocoagulation was used to damage the nasal mucosa in 480 of the rats before exposure. A high incidence, 28 percent, of nasal tumors occurred in rats with a damaged nasal mucosa exposed to 10ppm formaldehyde for 28 months. In the 29 rats with an intact nasal mucosa exposed to 10ppm formaldehyde for 28 months, only 1 developed a nasal tumor. In the other groups, exposed at lower concentrations, the incidence of nasal tumors was low and varied from 0 to 7 percent. Of the 32 rats with nasal tumors originating, or probably originating, from the internal nose, 28 cases were squamous cell carcinomas, of which 19 clearly originated from the nasal respiratory epithelium. The other nine squamous cell carcinomas derived from the epithelium lining the nasolachrymal duct and were seen in connection with severe odontodystrophy and periodontitis, or may have originated from the skin or salivary glands. The nasal tumors in the four other rats consisted of a polyploid adenoma, an adenocarcinoma, an adenosquamous carcinoma of the nasal respiratory epithelium, and a carcinoma in-situ of the nasolachrymal duct epithelium. The authors conclude that severe damage to the nasal mucosa can be an important factor in the induction of nasal tumors by formaldehyde.
DCN-163862; Textiles industry; Resins; Plastics industry; Vapors; Smoke inhalation; Paper manufacturing industry; Photochemical reactions; Carcinogenesis; Laboratory animals; Nasal cancer; Inhalants; Formaldehydes