Neurobehavioral effects of acute exposure to four solvents: meta-analyses

Meta- and reanalyses of the available data for the neurobehavioral effects of acute inhalation exposure to toluene were reported by Benignus et al. The present study was designed to test the generality of the toluene results in as many other solvents as possible by further meta- and reanalyses. Sufficient data for meta-analyses were found for only four solvents; toluene, trichloroethylene, perchloroethylene, and 1,1,1-trichloroethane. The results for these solvents showed that rats were less affected by each of the solvents when they were tested in highly motivating situations, for example, rewarded for rapid or correct responding or escape from electrical shock, compared with less motivating circumstances. The four solvents did not differ significantly in potency on any outcome measure when dose was expressed as molar brain concentration. When tested in tasks with low-motivational contingencies, the dose-effect curves of humans (reaction times) and rats (electrophysiological responses to visual stimuli) were not significantly different. However, on an exploratory follow-up analysis, humans were less sensitive than rats. No human data were found to test whether species differed under strong motivation. Dose-equivalence curves were derived for extrapolating to human effects from rat data.