An investigation of solvent-induced neuro-psychiatric disorders in spray painters

An index case of chronic toxic encephalopathy is described in a 28 year old male spray painter with eleven years of exposure to solvents at work. The patient had progressive affective symptoms following repeated past episodes suggestive of acute solvent intoxication. He also showed impaired performance on tests of auditory memory, perceptual speed, visual scanning, and manual dexterity, as well as electromyographic evidence of prolongation of distal terminal latency and slowing of conduction velocities. The case investigation was followed up with an epidemiological study of the factory where he worked, to determine if other spray painters might have similar excessive complaints of neuropsychiatric symptoms and/or objective neurobehavioural deficits. This involved 15 other male spray painters employed for at least five years, and a sex- and age-matched group of 15 control workers not exposed to solvents. The spray painters reported significantly more numbers of neurobehavioural symptoms than the controls. There were little differences in neurobehavioural test results, except for aiming test (psychomotor co-ordination) and Benton visual retention test (visual memory). Spray painters with four or more neurobehavioural symptoms also performed more poorly on Digit Symbol (perceptual speed) compared with those with less number of symptoms. The epidemiological results provide strong circumstantial basis for the diagnosis of chronic toxic encephalopathy in the patient, and also indicates a need for vigilance of the hazards of central nervous system disorders in workers with chronic exposure to solvents in Singapore.