Minamata Disease: Methylmercury Poisoning in Japan Caused by Environmental Pollution

Abstract

Minamata disease (M. d.) is methylmercury (MeHg) poisoning that occurred in humans who ingested fish and shellfish contaminated by MeHg discharged in waste water from a chemical plant (Chisso Co. Ltd.). It was in May 1956, that M. d. was first officially "discovered" in Minamata City, south-west region of Japan's Kyushu Island. The marine products in Minamata Bay displayed high levels of Hg contamination (5.61 to 35.7 ppm). The Hg content in hair of patients, their family and inhabitants of the Shiranui Sea coastline were also detected at high levels of Hg (max. 705 ppm). Typical symptoms of M. d. are as follows: sensory disturbances (glove and stocking type), ataxia, dysarthria, constriction of the visual field, auditory disturbances and tremor were also seen. Further, the fetus was poisoned by MeHg when their mothers ingested contaminated marine life (named congenital M. d.). The symptom of patients were serious, and extensive lesions of the brain were observed. While the number of grave cases with acute M. d. in the initial stage was decreasing, the numbers of chronic M. d. patients who manifested symptoms gradually over an extended period of time was on the increase. For the past 36 years, of the 2252 patients who have been officially recognized as having M. d., 1043 have died. This paper also discusses the recent remaining problems.

Exposure analysis of five fish-consuming populations for overexposure to methylmercury

“…The sensitive endpoints are impaired neurological development and long -term and/or delayed sequelae. The studies used to derive a TDI best address the former with long -term and /or delayed sequelae being effects that have only been observed and/ or studied in primates and in the catastrophic exposure to communities in Japan (Rice, 1992(Rice, , 1996Harada, 1995 ). There is uncertainty associated with toxicodynamic variations across the populations, although given the cohort sizes and types, this variation may be small ( Renwick, 1993;Dourson et al, 1996;ATSDR, 1997 ).…”

“…Exposure through diet has resulted in increased body burdens of methylmercury in human populations ( ATSDR, 1997;USEPA, 1997 ). Catastrophic exposure to communities in Japan and Iraq resulted in severe toxic and teratogenic effects ( Harada, 1995 ). Prenatal exposure to the fetus can lead to central nervous system damage, which can produce neurotoxic effects in children (ATSDR, 1997;USEPA, 1997 ).…”

Patterns and source analysis for atmospheric mercury at Auchencorth Moss, Scotland

“…19, 32, [34][35][36] Atmospheric mercury has become a more prominent interest with concerns about the effects of mercury on the health of both humans 37 and wildlife 38,39 ever since the diagnosis of Minamata disease in 1960 40 . The highest risk to human health is thought to be through the consumption of fish with high levels of bioaccumulated methylmercury by higher 60 predators.…”

Influences on and patterns in total gaseous mercury (TGM) at Harwell, England

“…Through improvements in industrial processes and emission controls, atmospheric mercury levels have been gradually declining since then 36,37 , and currently the average northern hemispherical background concentration is between 1.4 and 1.7 ng m -3 . 22,36,[38][39][40] Ever since the diagnosis of Minamata disease in 1960 41 , the effects of mercury on the health of both humans 42 and wildlife 43,44 has made the interest in atmospheric mercury more prominent, with the highest risk to human health thought to be through the consumption of fish with elevated levels of mercury, which have bioaccumulated through the food chain into higher predators [45][46][47] . Health policy reflects this risk, with several industrialised countries issuing fish consumption guidelines.…”