Neurological Effects of White Spirit: Contribution of Animal Studies during a 30-Year Period*.

Numerous studies have suggested that long-term occupational exposure to white spirit may cause chronic toxic encephalopathy (WHO 1996). This review summarizes the chronic nervous system effects of white spirit in animal studies during a 30-year period. First, routine histopathology was consistently unable to reveal adverse peripheral or central nervous system effects after inhalation of white spirit. Second, neurobehavioural studies in animals showed no adverse effect after inhalation of white spirit with a high content of aromatics in contrast to what was found with products with a low content. Third, white spirit with a high content of aromatics induced adverse neurochemical changes at inhalation of 400 ppm and possibly already at 100 ppm. In the studied parameters, white spirit with a low content of aromatics showed no clear adverse neurochemical effects at inhalation of 400 ppm, but the neurophysiological tests showed adverse effects at this level. Fourth, neurophysiological methods may be more sensitive than histopathological, neurobehavioural and neurochemical methods. Overall, white spirit with a high and a low content of aromatics showed no overt difference in long-term effects in animals, taking all studied end-points into account. The differences in sensitivity of the test methods should be taken into consideration if new toxicological studies are conducted on this type of solvents.