PRODUCTION OF HAIR INTERCOMPARISON MATERIALS FOR USE IN POPULATION MONITORING PROGRAMS FOR MERCURY AND METHYLMERCURY EXPOSURE

Ten kilograms of hair obtained from India were used as the basis for t wo intercomparison materials, one with natural low levels of mercury a nd methylmercury, and one with an elevated level of methylmercury. The latter was produced by labeling the hair with a solution containing m ethylmercury. To convert the hair into homogeneous powders, cryogenic milling was utilized. 70% of the final material passed through a 0.075 mm sieve. Subsequent studies were carried out to establish the homoge neity of the materials and the stability of the methylmercury label. T he materials will be distributed in an international intercomparison, the results from which will be used to obtain recommended values for t otal mercury and methylmercury.