A RECOMMENDED OCCUPATIONAL EXPOSURE LIMIT FOR FORMALDEHYDE BASED ON IRRITATION

In recent years, several regulatory agencies and professional societie s have recommended an occupational exposure limit (GEL) for formaldehy de. This article presents the findings of a panel of experts, the Indu strial Health Foundation panel, who were charged to identify an OEL th at would prevent irritation. To accomplish this task, they critiqued a pproximately 150 scientific articles. Unlike many other chemicals, a l arge amount of data is available upon which to base a concentration-re sponse relationship for human irritation. A mathematical model develop ed by Kane et al. (1979) for predicting safe levels of exposure to irr itants based on animal data was also evaluated. The panel concluded th at for most persons, eye irritation clearly due to formaldehyde does n ot occur until at least 1.0 ppm. information from controlled studies i nvolving volunteers indicated that moderate to severe eye, nose, and t hroat irritation does not occur for most persons until airborne concen trations exceed 2.0-3.0 ppm. The data indicated that below 1.0 ppm, if irritation occurs in some persons, the effects rapidly subside due to ''accommodation.'' Based on the weight of evidence from published stu dies, the panel found that persons exposed to 0.3 ppm for 4-6 h in cha mber studies generally reported eye irritation at a rate no different than that observed when persons were exposed to clean air. It was note d that at a concentration of 0.5 ppm (8-h TWA) eye irritation was not observed in the majority of workers (about 80%). Consequently, the pan el recommended an OEL of 0.3 ppm as an 8-h time-weighted average (TWA) with a ceiling value (CV) of 1.0 ppm (a concentration not tb be excee ded) to avoid irritation. The panel believes that the ACGIH TLV of 0.3 ppm as a ceiling value was unnecessarily restrictive and that this va lue may have been based on the TLV committee's interpretation of the s ignificance of studies involving self-reported responses at concentrat ions less than 0.5 ppm. The panel concluded that any occupational or e nvironmental guideline for formaldehyde should be based primarily on c ontrolled studies in humans, since nearly all other studies are compro mised by the presence of other contaminants. The panel also concluded that ii concentrations of formaldehyde are kept below 0.1 ppm in the i ndoor environment (where exposures might occur 24 h/d) this should pre vent irritation in virtually all persons. The panel could not identify a group of persons who were hypersensitive, nor was there evidence th at anyone could be sensitized (develop an allergy) following inhalatio n exposure to formaldehyde. The panel concluded that there was suffici ent evidence to show that persons with asthma respond no differently t han healthy individuals following exposure to concentrations up to 3.0 ppm. Although cancer risk was not a topic that received exhaustive ev aluation, the panel agreed with other scientific groups who have concl uded that the cancer risk of formaldehyde is negligible at airborne co ncentrations that do not produce chronic irritation.