Mutation Research, 116 (1983) 417-422 417 Elsevier Biomedical Press Formaldehyde is mutagenic for cultured human cells Victor S. Goldmacher and William G. Thilly Department of Nutrition and Food Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (U.S.A.) (Received26 January 1982) (Revisionreceived24 May 1982) (Accepted 16 July 1982) Summary We have found formaldehyde to be mutagenic for human cells in culture. At concentrations above 130 #M or 4 parts per million by weight (2 h exposure at 37°C), formaldehyde induces the appearance of F3TdR-resistant mutants in the diploid human lymphoblastoid TK6 line. This finding suggests but does not prove that formaldehyde is a mutagenic hazard for humans. Because formaldehyde is produced at a level of several billion pounds per year in the United States (USITC, 1979) and is widely used in industry and medicine, it is important to determine its mutagenic and carcinogenic potential to humans who are exposed to this compound. More than 60 categories of industrial and laboratory workers are exposed to formaldehyde in air and solutions (Fishbein, 1978; Blackwell et al., 198 l; Sax, 1981). In addition, formaldehyde has been found as an urban and industrial air pollutant (Hoffman and Wynder, 1976; Blackwell et al., 1981), in tobacco smoke (Osborne et al., 1956; Mold and McRae, 1957; Newsome et al., 1965), in products of the thermal degradation of polymeric materials (Stuart and Smith, 1965), in automobile and diesel exhaust fumes (Wilson, 1960; Altshuller et al., 1961) and in incinerator effluents (Stenburg et al., 1961). Formaldehyde is suspected to be a human carcinogen for several reasons. Exposure of rats and mice to formaldehyde vapor in laboratory studies caused carcinogenic effects (Swenberg et al., 1980; Blackwell et al., 1981). The compound has been found to be mutagenic for some bacteria, insects, flowering plants, and fungi (see Auerbach et al., 1977, for a review). Formaldehyde induced sister-chro- matid exchanges in Chinese hamster ovary cells and in human lymphocytes (Obe and Ristow, 1979), and also induced unscheduled DNA synthesis in HeLa cells (Martin et al., 1978). It is not yet clear, however, whether formaldehyde presents a hazard for humans, since other investigations have produced conflicting results. For 0165-1218/83/0000-0000/$03.00 © ElsevierBiomedical Press