Question

Why toxicity of dimethyl mercury increases in presence of cobalt?

Answer 1

Note: I could not find any reaction of dimethyl mercury and cobalt or enhancement of toxicity of dimethyl mercury. This is the information I was able to collect.

Dimethyl mercury is a volatile, sweet smelling compound. Even a 0.1 mL of dimethyl mercury can cause the death of human. This happened with Dr.Karen Wetterhahn, a world renowned chemist working on heavy metal effect on biological system. She had few drops of dimethyl mercury in backside of latex gloves. Dimethyl mercury being able to penetrate skin wen into her biological system. Dimethyl is one of the worst known neurotoxin. It is probably due to the complexation of Hg with cysteine in the brain cells which disrupts the biological process which ultimately leads to death.

Now, though the mercury metal is not toxic to our body. it passes through without being absorbed. But methyl mercury can get absorbed easily and effect the central nervous system.

In 1950, Minamata a city Japan had strange observation. Animals like cats and dogs behaved strangely, birds dropped while flying. After sometime the fish was banned in the city. It was found that a company dumped lot of heavy metal waste in to the sea. The water was contaminated mostly with mercury. Now when mercury enters the human body it gets converted to methylmercury hydroxide. There is cobalt complex called methylcobalamin which is also a derivative of vitamin B12. methyl mercury is soluble in water, and

$CH_3Hg^+$ actually responsible for toxicity of dimethyl mercury also. it is one the which gets coordinated with important biological component and disrupts the system.

Methylcobalamin can methylate the mercury which means it can convert the mercury to $CH_3Hg^+$. So any organism which can produce methylcobalamin will cause accumulation of mercury in body by forming $CH_3Hg^+$. This is called bioaccumulation. This causes mercury poisoning and that is why mercury poisoning is also minamata disease. Because it was like a epidemic in MInamata,Japan