Effects of long-term exposure to solvents in the paint industry. A cross-sectional epidemiologic study with clinical and laboratory methods.

The effects of organic solvents on 50 male workers exposed 5-46 (mean 18) years were studied with a cross-sectional design. Referents were matched pairwise according to age and education. An analysis of confounders confirmed good comparability between the two groups. As indicators of organic brain dysfunction regional cerebral blood flow was measured and the power spectrum of the subjects' electroencephalograms was analyzed, the former being reduced 4% and the latter showing increased power in the delta and beta bands in the exposed group. Symptoms of brain dysfunction were significantly more frequent among the exposed subjects and showed an exposure-effect relationship. Neuropsychological tests revealed definite indication of brain dysfunction in 14% of the exposed subjects in comparison to none in the reference group. The exposed subjects performed significantly worse than the referents in tests measuring focused attention abilities. A neurophysiological examination of the peripheral nervous system showed no difference between the groups. Clinical chemistry demonstrated no differences that could be explained by solvent exposure.

Regional cerebral blood flow and verbal memory after chronic exposure to organic solvents.

Regional cerebral blood flow (rCBF; 133Xe-inhalation method) was investigated in 32 industrial workers (age: 51 +/- 9 years) who had been exposed to organic solvents during an average of 24.5 years. The measurements were made at rest and during learning of associated word pairs. The resting flow level was 17% lower than expected for normal subjects of similar age and the activation-induced changes of rCBF during the test lacked the frontal activation normally seen. Significant correlations between age, length of exposure, and rCBF level were found. In order to control for the age factor, results were also calculated from two subgroups of similar age but with very different levels of exposure (13 and 31 years of average exposure). The two groups differed only slightly in resting rCBF. A marked difference was, however, seen during activation, with significant post-central flow increases recorded in the lower-exposed group only. The results indicate the potential of the rCBF method for elucidating functional cortical changes related to neurotoxic effects of organic solvents.

Neurophysiological observations after chronic styrene exposure.

Thirty-three styrene exposed workers from three different industrial sites were examined with electroencephalography and motor and sensory neurography. The three groups had respective styrene exposures of clearly above the threshold limit value (50 ppm), at about this level, and clearly below it. The neurophysiological results were compared with those of a group of normal controls and a group of 17 patients judged to suffer from sequelae after long-term heavy exposure to organic solvents (mainly painters). Ten subjects in the styrene group presented signs of a mild sensory neuropathy with polyphasic sensory responses of a low amplitude. The same pattern was commonly found among the reference group heavily exposed to solvents. The ten subjects in the styrene group with mild polyneuropathy had a significantly higher age and significantly heavier styrene exposure than the rest of the group. Age difference could not explain the difference in the neurophysiological parameters, and therefore the contributing role of styrene exposure has to be considered. The electroencephalographic analysis showed no changes of the dominant alpha frequency. An increased amount of diffuse slow activity was seen in many of the heavily exposed mixed-solvent cases and was seen in some of the styrene-exposed cases without a clear relation to degree of exposure. An increased occurrence of fast activity in central and precentral areas of the brain was found in the styrene group, as well as in the mixed-solvent group. This pilot study indicates that the same type of neurophysiological changes from the strictly normal are seen among workers exposed to styrene as those found among a group of patients judged to suffer from sequelae after chronic exposure to various organic solvents. The neurophysiological "profile" is (a) sensory nerve responses with low amplitude and long duration, (b) somewhat low sensory conduction velocities, (c) close to normal motor neurographic findings, and (d) an increased amount of fast activity in central and precentral regions in the electroencephalogram in combination with normal occipital alpha activity.

Chronic hepatic encephalopathy. A psychometrical study.

Psychometric tests were performed in 41 patients with cirrhosis of the liver and suspected hepatic encephalopathy and compared with EEG-examinations and clinical investigations. Marked intellectual impairment was noted frequently even when the clinical investigation was normal. This difference was mainly due to the preserved verbal ability of the patient. The etiology of the cirrhosis did not influence the test results. Male cirrhotic patients with and without alcoholism showed significantly more intellectual impairment then alcoholics without cirrhosis. Patients Patients with constructed porto-systemic shunts showed only slightly reduced intellectual ability compared to those without shunts.