Incidents exposure, formaldehyde

Avoid inhalation of vapor and contact with eyes or skin. Primary effects probably are due to fairly rapid formation of hydrochloric acid, formaldehyde, and methanol. A high incidence of lung cancer has been observed after chronic exposure.3 Animal and human carcinogen.5 Exposure by all routes should be carefully controlled to lowest possible levels.6... 

It should be noted that evidence derived largely from animal and cell-based studies indicates that both MTBE and ETBE are oxidatively demethylated to produce t-butyl alcohol (TBA). MTBE is also metabolized to formaldehyde. Both TBA and formaldehyde are potentially carcinogenic. In all the studies with rodents, MTBE and TBA increased tumor incidence only at very high oral or inhalation exposures, levels that would not be encountered by humans for prolonged periods of time. 

In general, observations of increased mortality in the rat bioassays occurred after about one year of exposure and were associated with the development of nasal squamous cell carcinomas. Golden Syrian hamsters exposed to 10 ppm formaldehyde, 5 hours/day, 5 days/week for life showed a small, but statistically significant, increase in mortality compared with controls, but no increased incidence of nasal tumors and only a minimal (5% versus zero in controls) increased incidence of hyperplasia or metaplasia in the nasal epithelium (Dalbey 1982). No exposure-related increased mortality was found in B6C3F1 mice exposed to up to 14.3 ppm for 6 hours/day, 5 days/week for 24 months (Kerns et al. 

Harrington and Oakes (1984) established a population of 2,307 men and 413 women to study the incidence of cancer induction due to formaldehyde exposure in humans. During the study period, 126 of these pathologists died death certificates were obtained for 121 of them. Observed and expected deaths... 

Animal Cancer Studies As discussed previously in Section 2.2.1.2 subsection entitled Chronic Inhalation Animal Studies, chronic exposure to airborne formaldehyde concentrations ranging from about 6 ppm to 15 ppm induced increased incidences of nasal tumors (squamous cell carcinomas, squamous cell papillomas, or polyploid adenomas) in three bioassays with Fisher 344 rats (Kamata et al. 1997 Kems et al. 1983b Monticello et al. 1996 Swenberg et al. 1980). Increased incidences of lower respiratory tract tumors or distant site tumors were not found in these studies, and exposure to concentrations of 2 ppm and lower induced no malignant nasal tumors. 

No studies were located regarding cancer rates in humans predominantly exposed to formaldehyde via the dermal route. Animal cancer studies of dermal exposure are restricted to two studies that found no statistically significant increased incidences of skin tumors in mice exposed twice weekly for 58-60 weeks to solutions containing up to 4% (Iverson 1988) or 10% formaldehyde (Iverson 1986). 

No studies were loeated examining potential relationships between skin eancer in humans and dermal exposure to formaldehyde, but two mouse-skin cancer bioassays found no evidence for increased incidence of skin tumors after 58-60 weeks of twice-weekly exposure to formaldehyde solutions at concentrations of 4% (Iverson 1988) and 10% (Iverson 1986). Additional animal bioassays employing lifetime dermal exposure scenarios would provide more complete assessments of the possible dermal carcinogenicity of formaldehyde. 

Grazuleviciene R, Dulskiene V, Vencloviene J. 1998. Formaldehyde exposure and low birth weight incidence. J Occup Health 40 61-67. 

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