Masazumi Harada

Mercury and methylmercury in fish and human hair from the Tapajós river basin, Brazil

Mercury is being released in the Amazon in an abusive way due to goldmining activities. The Tapajós river basin was the first to be intensively exploited in the modern Amazon gold rush. Fish and hair samples as the best indicators of human methylmercury contamination were investigated in the main cities and villages along the Tapajós river basin. The upper basin has typical fish fauna with much larger carnivorous fish with higher mercury levels reaching an average value of 0.69 microgram.g-1 wet wt. in 43 fish. This was accompanied by high levels in hair of the human population living in the same area. The maximum hair value reach 151 micrograms.g-1 dry wt. with two villages presenting an average value close to 25 micrograms.g-1 dry wt. An analytical laboratory intercalibration exercise was performed between Japanese and Brazilian laboratories for total mercury analysis. Critical fish, areas, and more exposed human groups are identified.

Methylmercury pollution in the Amazon, Brazil

In order to evaluate the extent of environmental mercury pollution due to goldmining activities in the Amazon, concentrations of total mercury and methylmercury were determined for human hair and fish samples from five fishing villages located mainly in the Tapajos river basin. Abnormally high levels of mercury were found in human hair from Jacareacanga and Brasilia Legal located near the main goldmining area as well as from Tres Bocas facing the lake in Amapa state, whereas the levels were much lower in Ponta de Pedras, a long way downstream. The values of male samples were about twice as high as females even in the same family. The predominant form of mercury in hair samples was methylmercury (average 90%), while high hair mercury observed in goldminers and workers in goldshops was mostly in the inorganic form. Longitudinal analyses of long hairs from people in fishing villages showed fairly constant and continuous exposure to methylmercury at least over the last few years with seasonal variations. Fish contained relatively high levels of mercury (up to 3.82 ppm) mostly in the form of methylmercury and most of the fish from upstream and some from downstream exceeded the allowable level of 0.5 ppm in Brazil.

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.

Methylmercury level in umbilical cords from patients with congenital Minamata disease

A total of 151 umbilical cords during the period from 1950 to 1969 were collected from the residents of the Minamata area (including 25 patients with congenital Minamata disease) for methylmercury (MeHg) analysis. When the MeHg discharge from the Chisso Companys Minamata factory into the Minamata Bay is compared with the incidence of congenital Minamata disease, the abrupt increase of the former in 1952 [Nishimura H. Chem. Today 1998;323:60-66] was found to precede that of the latter by approximately 2 years, thereby indicating that MeHg is the cause of the disaster. This was confirmed by the elevated levels of MeHg in the umbilical cords from residents of the Minamata area [from 0.35 +/- 0.30 (S.D.) ppm in 1952 to 0.96 +/- 0.75 ppm in 1955], the MeHg levels (1.60 +/- 1.00 ppm) in the cords from patients with congenital Minamata disease showing the highest values [P < 0.01 vs. acquired Minamata disease (0.72 +/- 0.65 ppm), mental retardation (0.74 +/- 0.64 ppm), other diseases (0.22 +/- 0.15 ppm), and no symptoms (0.28 +/- 0.20 ppm), respectively]. Thus, in order to fill a gap, which extends over a long period of time, in studies on environmental Hg pollution, umbilical cord samples were considered to be a useful tool.

Mercury in feathers of wild birds from the mercury - polluted area along the shore of the Shiranui Sea, Japan

Total mercury content in the feathers of 95 stuffed, wild birds collected all over the shore of the Shiranui Sea (where Minamata disease occurred in many towns and villages in the 1960s) was measured. They were collected over 25 years, from 1955 to 1980. They showed relatively high mercury levels till the late 1970s, although drainage of waste water containing methylmercury from the Chisso Corporations Minamata Factory was stopped in 1968. In addition, a strong correlation between feeding habits and mercury content was observed; thus the five groups in order of diminishing mercury content were: fish-eating sea birds (mean +/- SD = 7.1 +/- 3.7 ppm, n = 14), omnivorous water fowl (5.5 +/- 5.6 ppm, n = 17), predatory birds (3.6 +/- 2.9 ppm, n = 16), omnivorous terrestrial birds (1.5 +/- 1.2 ppm, n = 31), and herbivorous water fowl (0.9 +/- 0.4 ppm, n = 17). Mercury content of the feathers of omnivorous terrestrial birds in the Shiranui Sea was exceedingly high compared with those in China and Korea. The findings in the present study suggest that stuffed, wild birds may be a good index of past environmental pollution.

Methods of removing external metal contamination from hair samples for environmental monitoring

Human exposure to trace elements has become a major environmental issue with the growing industrialization and urbanization around the world. Hair samples are the most conveniently obtainable biopsy material and they have been identified as good indicators of the metal pollution in an environment. For their effective use, however, it is necessary to exclude the effect of external contamination of the hair surface by metals. The present investigation compares the different methods of washing hair samples prior to further treatment for elemental analysis. Deionized water, solvents (acetone, ether and carbon tetrachloride), non-ionic detergent, ionic detergent (sodium lauryl sulfate), chelating agent (EDTA-2Na), ultrasonics and combinations of these agents were used in the experiments. EDTA was found to be the most suitable of these washing agents for removing external contaminant metals. Further elucidation, however, is needed before a standard method of hair washing can be established.

Determination of carbonic anhydrase C and β2-microglobulin by radioimmunoassay in urine of heavy-metal-exposed subjects and patients with renal tubular acidosis

Abstract Carbonic anhydrase C (CA-C) was measured by the radioimmunoassay in urine specimens from normal individuals, residents in mercury-polluted area, cadmium-exposed workers, lead-exposed workers, and patients with primary or secondary renal tubular acidosis. None of the urine in the normal subjects demonstrated CA-C levels above 40 μg/g creatinine. Some of the cadmium-exposed workers, residents in mercury-polluted area, and patients with renal tubular acidosis excreted large amounts of CA-C that were 10–250 times higher than the normal. Urinary β2-microglobulin (BMG) was also determined in relation to the CA-C levels. Most of the subjects exposed to heavy metals had high levels of urine CA-C or BMG or both. Some individuals had high levels of urine CA-C although BMG levels were within normal values. These findings seem to suggest that the mechanisms of urinary excretion of these two proteins were different and the quantitative determination of urinary CA-C by radioimmunoassay appears to be also a useful and sensitive test for detecting the renal tubular disorders in environmental exposure of heavy metals or those in renal tubular acidosis.

A study of the sources of external metal contamination of hair

Sources of external metal contamination of hair were examined experimentally by exposing hair samples to soil, hot water from a water boiler for domestic use and household dust and fumes in a kitchen. Copper concentration in the hair increased markedly only when the hair was exposed to hot water from the boiler. Iron concentration in the hair increased markedly after exposure to wet soil, and increased slightly after exposure to hot water from the boiler. There was a slight decrease in zinc in the hair after exposure to wet or moist soil, and a significant increase after exposure to hot water from the boiler. When the hair was exposed to household dust and fumes, zinc showed a slight increase but copper and iron showed no change at all. The experiments with soil demonstrated the importance of water in the movement of iron from soil to hair and the role played in this process by biological factors such as soil bacteria.

Mercury content of head hair from residents on the coast of Jakarta Bay.

An indication of mercury accumulation in some regions of Jakarta Bay was recently reported. The average mercury concentrations greatly exceed the normal level of mercury in sea water. The present paper describes the mercury content of hair from residents on the coast of Jakarta Bay in order to examine whether or not the environmental pollution has already exerted a deleterious effect on the human body.

Epidemiological and Clinical Study of Mercury Pollution on Indian Reservations in Northwestern Ontario, Canada

Two Indian reservations, Grassy Narrows and White Dog in Ontario, Canada, are polluted by mercury discharged from a caustic soda plant in Dryden. Mercury concentration in fish is high, and cats eating such fish are poisoned by methyl mercury. Among inhabitants who eat fish, high mercury concentrations are detected in the blood as well as the hair, and apparently such inhabitants are contaminated by mercury. These facts were elucidated from data made public by our own research. The situation is clearly a reenactment of what happened in Minamata and Niigata, Japan.