Formaldehyde: evidence of carcinogenicity.

The National Institute for Occupational Safety and Health (NIOSH) recommends that formaldehyde be considered a potential occupational carcinogen and that appropriate measures be taken to reduce worker exposure. It is a colorless, flammable gas with a strong pungent odor. It is an important industrial chemical of major commercial use and is found throughout the environment. Formaldehyde is usually manufactured by reacting methanol vapor and air over a catalyst, and is sold mainly as an aqueous solution. 1/2 of the formaldehyde produced is in turn used to produce synthetic resins which are primarily used as adhesives. Its widespread use is due to its high reactivity, colorlessness, purity in commercial form, and low cost. Various products made with or containing formaldehyde are listed in a table. NIOSH estimated that 1.6 million workers were exposed to formaldehyde in a 2-year period (1972-74), and of these workers, 57,000 workers were exposed for 4 or more hours/day. The occupational groups exposed to formaldehyde are listed in Appendix 1. It was recommended by NIOSH in 1976 that employee exposure to formaldehyde in the work environment be no greater than 1.2 mg/cubic meter of air (1 ppm) for any 30-minute sampling period. This was prior to knowledge about the carcinogenic potential which was first reported in October 8, 1979, based on laboratory animal studies. Formaldehyde was carcinogenic in rats exposed to 15 ppm for 6 hours/day, 5 days/week, for 16 months. Formaldehyde caused nasal cancer in these rats. Epidemiologic studies conducted to date do not permit a definitive evaluation of the carcinogenic risk to humans. However, a panel of scientists concluded that it would be wise to consider formaldehyde as posing a carcinogenic risk to humans. In addition, it has been known to be mutagenic. Other health effects include burning of the eyes, irritation to upper respiratory passages, pneumonitis, wheezing, productive cough, and dermatitis. NIOSH recommends that formaldehyde be handled in the workplace as a potential occupational carcinogen. Exposure to it should be decreased to reduce the probability of developing cancer. Appendices contain guidelines for minimizing worker exposure to formaldehyde, formaldehyde concentrations by industry, and a list of major formaldehyde manufacturers.