Manganese in scalp hair: problems of exogenous manganese and implications for manganese monitoring in Groote Eylandt Aborigines.

The use of scalp hair to monitor manganese was studied as part of an investigation of manganese intoxication amongst a group of Aborigines living on manganese-rich soil on Groote Eylandt, in the Northern Territory of Australia. High scalp-hair manganese values were due largely to manganese from exogenous sources. Manganese (IV) dioxide in dust, trapped in hair, was reduced by the components of sweat, leading to the diffusion of manganese (II) into the hair shaft. At least 15 micrograms Mn g-1 hair could be incorporated into hair via this exogenous route. To overcome the problems of manganese contamination, the ability of a number of leaching agents to remove exogenous manganese selectively from hair was tested. Measurements of manganese along the length of hair strands were extrapolated back to zero length to estimate the amount of manganese in the hair as it emerged from the scalp. Using this extrapolation technique, Aborigines on Groote Eylandt had a mean scalp-hair manganese of 16 ppm. Aborigines in non-manganese areas had 2 ppm manganese in hair. Caucasians living in the same manganese-rich area had 2.5 ppm manganese in hair, compared to 0.5 ppm manganese in non-manganese areas. Measurements of manganese in hair and blood of Groote Eylandt Aborigines showed that the population had a high exposure to manganese, but did not distinguish between those individuals affected/unaffected by the neurological condition, Groote Eylandt Syndrome.