Effect of chronic exposure to acrylonitrile on subjective symptoms.

A cross-sectional study was performed to clarify the relationship between exposure to acrylonitrile (AN) and its effect on subjective symptoms by using a modified Cornell Medical Index (CMI) health questionnaire. The 7 acrylic fiber manufacturing factories surveyed were classified into 3 groups, namely, group L with a mean environmental acrylonitrile concentration of 1.8 ppm, group M with 7.4 ppm, and group H with 14.1 ppm. The total number of workers engaged in acrylic fiber manufacturing processes (acrylonitrile workers) and reference workers analyzed were 504 and 249, respectively. These consisted of 92 acrylonitrile workers and 108 reference workers in group L, 304 and 102 respectively in group M, and 108 and 39 respectively in group H. The mean values for length of exposure to acrylonitrile were 5.6 years in group L, 7.0 years in group M, and 8.6 years in group H. Neurotic status as determined by Fukamachi's criteria and Cornell Medical Index profiles did not show any AN-related differences between AN workers and reference workers in any of the groups. The subjective symptoms with significantly high prevalences in AN workers were "headache", "tongue trouble", "choking lump in throat", "fatigability", "general malaise", "heavy arms", and "heavy sweating". Except for "choking lump in throat" there was no relationship between the prevalence of symptoms and the length or level of exposure to acrylonitrile. These results suggested that long-term exposure to acrylonitrile at levels up to 14.1 ppm did not induce neurotic effects in acrylonitrile workers, but might cause some reversible subjective symptoms.