Prevalence of abnormal neurobehavioral scores in populations exposed to different industrial chemicals.

The aim of the study is to establish the prevalence of neurobehavioral scores of occupationally exposed subjects below the 10th percentile rank of normalized curves obtained on a referent population. The Milan Automated Neurobehavioral System (MANS) was administered to 400 drivers from public and private firms; their data were distributed on the basis of age and years of school attendance and were normalized by determining percentile rank equivalence. The exposed population is made up of 20 lead- and zinc-exposed subjects, 18 welders exposed to aluminum for less than 1 year, 150 exposed to different metals in the ferromanganese production, 73 lithographic operators exposed to gasoline and petroleum, 197 exposed to solvents mixtures in the paint manufacture, and 23 dropouts of the same firm. The percentages of scores below 10th percentile rank were calculated in the different exposure groups and in the different age-school attendance ranges. The prevalence of results below the 10th percentile rank was found to be related to the intensity of the exposures and to the low levels of school attendance. In the 20-29 and the 30-39 age ranges, there was a prevalence of POMS scale scores below 10th percentile rank, in the 50-59 age range, the percentages were high for the Digit Symbol, the mean value of Simple Reaction Time, Serial Digit Learning, and Benton Visual Recognition.