People are fond of seafood. The many variants of seafood prepared in exclusive spices and presented in delectable sauces are enticing dishes in many parts of the world. However, recently there have been suggestions to limit the consumption of certain fish. Have you ever wondered why some fishes are to be avoided? It is because certain small fishes accumulate greater quantities of mercury which is detrimental to human health. But how does mercury enter the ocean? The sources of toxic mercury entering the ocean are still a mystery but it is understood that a phenomenon called the mercury cycle could be the answer. Mercury cycle is a process by which mercury is transferred from earth to the atmosphere, from where it is transferred to the oceans which once again reaches earth. When in the ocean, mercury is converted to monomethyl mercury which enters the food chain via small fishes like tuna and swordfish which are consumed by people in large quantities.

Mercury that enters the water bodies from sources on land or air is in its element form which is not harmful because it can be gotten rid of easily. But the toxic form of mercury that enters fish is a methyl group which means that CH3 is attached to the mercury atom. How and from where does this dangerous compound of mercury enters the ocean is still perplexing scientists all over the world. The blighting effects of methyl mercury have long-standing repercussions in humans. Continued exposure of pregnant women may cause neonatal deformities in future generations. Minamata Bay in Japan is the worst affected area because of large quantities of methyl mercury. In Minamata Bay, the source of the lethal compound was clear, a chemical plant in the vicinity, but what about the source of the fatal methyl mercury globally? Studies should be dedicated to find out the sources and eradicate this harmful phenomenon at the earliest before it is too late.