NEUROBEHAVIORAL FUNCTIONS AMONG WORKERS EXPOSED TO MANGANESE ORE

The Neurobehavioral Core Test Battery of the World Health Organization was performed on 17 baggers (mean age 36.6 years) in a manganese ore milling plant and 17 referents (mean age 35.7 years). The baggers had a mean exposure period of 7.4 (range 1-14) years with a mean blood man ganese concentration of 25.3 (range 15-92.5) mug . l-1 [0.46 (0.27-1.6 8) mumol . l-1]. Of the 37 symptoms related to the nervous system, 20 were more frequently reported by the exposed workers. No significant d ifferences were noted between the nerve conduction of the median and u lnar nerves of the dominant forearm of the two groups. The exposed-wor kers had significantly poorer motor speed, visual scanning, visuomotor coordination, visuomotor and response speed, and visuomotor coordinat ion and steadiness. A clinical examination did not reveal any abnormal ity among the two groups. Hence a neurobehavioral test battery may be a more sensitive method than a clinical examination in detecting early changes in motor function among manganese-exposed workers.