Methylmercury teratogen

Most cases of mercury poisoning led to handicap, chronic disease, or death. The most frequent symptoms include numbness of limbs, lips and tongue, speech abnormalities, limb function disorders, visual acuity disorders, deafness, and muscular atrophy. Insomnia, hyperactivity, and coma have also been reported. Methylmercury penetrates the blood-brain barrier and causes central nervous system injuries. Mercury also has a teratogenic effect, leading to congenital abnormalities or congenital Minamata disease. 

A common example of neurobehavioral teratogenic effects caused by polluted food is the Minamata disease. In a number of areas in Japan methylmercury from industrial waste accumulated in fish which was one of the main sources of the food of the local population. Another case of poisoning with methylmercury occurred in Iraq, where people consumed grain seed treated with a methylmercury fungicide. Women with only minimal poisoning symptoms gave birth to children that showed many neurological and behavioral abnormalities, such as mental retardation, coordination deficits and seizures (refs. 12, 13). 

Methylmercury causes neurotoxicological effects in cats and dogs. Cats ingesting contaminated fish around Minamata Bay, Japan, died after paroxysmal fits (i.e., cat-dancing disease ). Mink are particularly sensitive to the toxicity of methylmercury. Methylmercury is also fetotoxic and teratogenic in laboratory mammals. 

Nobunaga T, Satoh H, Suzuki T. 1979. Effects of sodium selenite on methylmercury embryotoxicity and teratogenicity in mice. Toxicol Appl Pharmacol 47 79-88. 

Nolen GA, Buchler EV, Geil RG, et al. 1972. Effects of trisodium nitrotriacetate on cadmium and methylmercury toxicity and teratogenicity in rats. Toxicol Appl Pharmacol 23 222-237. 

Su M, Okita GT. 1976. Embryocidal and teratogenic effects of methylmercury in mice. Toxicol Appl Pharmacol 38 207-216. 

Khera, K.S. 1973b. Teratogenic effects of methylmercury in the cat Note on the use of this species as a model for teratogenicity studies. Teratology 8(3) 293-303. 

Minamata disease was first discovered in 1956 around Minamata Bay, Japan. A similar epidemic occurred in 1965 along the Agano river, Japan. Minamata disease is methyl mercury poisoning that occurred in humans who ingested fish contaminated with methylmercury discharged in waste water from a chemical plant. Methylmercury is also teratogenic (Ui 1992, Harada 1995, Eto 1997, Schardein 2000 see also Part III, Chapter 17). 

Teratogenicity of methylmercury has been confirmed in mice, hamsters, and rats. 

Studies with mice indicated teratogenic effects in subsequent generations, i.e., surviving males from methylmercury-intoxicated dams mated with untreated females produced... 

Hoffman, D. J. and Moore, J. M. (1979) Teratogenic effects of external egg applications of methylmercury in the Mallard, Anas platyrhynchos. Teratology 20, 453-462. 

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