Monitoring of mercury pollution in Tanzania: relation between head hair mercury and health.

Through 1996 into 1997, a spot investigation on mercury contamination was conducted three times in Tanzania, especially around the Lake Victoria. A total of 150 goldminers, 103 fishermen and their families, and 19 residents of Mwanza City volunteered for the current study. A high total mercury level of 48.3 ppm (near to 50 ppm, a critical level of Minamata disease) and over in the head hair was observed in six goldminers (highest value, 953 ppm), four fishermen and their families (highest value, 416 ppm), and four Mwanza people (highest value, 474 ppm). With the exception of these 14 subjects, however, each mean total mercury level was well within the normal range (below 10 ppm). Out of the goldminers examined, 14 cases were diagnosed as a mild form of inorganic-mercury poisoning according to their clinical symptoms (such as polyneuropathy mercurialis, neuroasthemia, or tremor mercurialis) and the low ratio of methylmercury to total mercury, whereas neither inorganic-mercury poisoning nor methylmercury poisoning (Minamata disease) was noted in the fishermen and their families or in the Mwanza people. In addition, some subjects who showed a high total mercury level made habitual use of toilet soap containing much mercury. The findings obtained suggest that the mercury pollution in Tanzania is not very serious, however, it should be observed continuously.