Neurophysiological effects of long-term exposure to a mixture of organic solvents.

Abstract

Neurophysiological effects of long-term exposure to a mixture of organic solvents was studied among 102 car painters from 27 car repair garages in Helsinki [Finland]. The reference group consisted of 102 age-matched railroad engineers from the Finnish State Railways. The mean age was 35 yr and the exposure time ranged from 1-40 yr (mean 14.8, SD 8.5). According to measurements the mean concentration of the solvent mixture was relatively low in the garages, namely, 31.8% of the Finnish threshold limit value (TLV), the range of separate components varying from 4-212% of the respective TLV. The main components of about 20 organic solvents of the mixture were toluene, xylene, butyl acetate and white spirit. EEG of all the 102 exposed and 102 nonexposed subjects were studied, but electroneuromyographic measurements were made of only 59 car painters and 53 referents with a similar age distribution. Maximal motor conduction velocity (MCV), conduction velocity of slower motor fibers (CVSF), maximal sensory conduction velocity (SCV) and motor distal latencies velocity, were recorded from nerves in the upper and lowr extremities. Abnormal EEG were encountered in 32 car painters and 37 referents. The frequency of abnormal EEG was higher in both groups than expected on the basis of EEG literature (about 10%). Car painters (26) had a complex of 4 common symptoms of disturbances in the CNS; the same symptom complex was found in 12 engineers. Forty-six percent of the car painters with this symptom complex had an abnormal EEG, while only 26% of those without this symptom complex had an abnormal EEG. Railroad engineers did not show such a tendency. Abnormally slow MCV or SCV and/or prolonged motor distal latencies were found in 12 of the 59 car painters but in none of the 53 engineers studied. Many solvents primarily cause neuropathy, while objective signs of central nervous involvement are minor, if any. Slight positive signs of slowed nerve conduction velocities among the car painters and no increase in EEG abnormalities in comparison to the reference group of railroad engineers were shown.