ABSENCE OF MUTAGENICITY IN PERIPHERAL LYMPHOCYTES OF WORKERS OCCUPATIONALLY EXPOSED TO METHYL-METHACRYLATE

Chromosome aberration rates and sister chromatid exchange frequency we re examined in the peripheral lymphocytes of 38 male workers who were engaged in organic glass production and exposed to methyl methacrylate (MMA) vapors at the concentrations of 0.9 ppm to 71.9 ppm. The result s were compared with the findings in the concurrent nonexposed male su bjects. Comparison of the exposed group with the nonexposed controls s howed that there were no exposure-related changes in chromosome aberra tion rate. SCE frequency was higher in the exposed group than in the c ontrols, but this was considered to be due to higher ages of the forme r group than that of the latter. In fact, selection of nonsmokers and further classification of the exposed nonsmokers into two groups of th ose with exposure below and above a median MMA concentration (ca. 4 pp m) failed to show any difference among the three nonsmoking groups in cytogenetic parameters, or any dose-dependency, The present results, a lthough in a limited number of subjects, indicate that occupational me thyl methacrylate exposure under the conditions studied is not associa ted with mutagenicity. This conclusion confirms the absence of mutagen icity of methyl methacrylate in humans, and is in general agreement wi th a majority of the results of studies on mutagenicity in vitro, anim al carcinogenicity and occupational cancer epidemiology of methyl meth acrylate.