Mercury Contamination in Fish

The cycle of mercury contamination in fish

        Generally, there are 2 types of mercury, the organic and inorganic. When the inorganic mercury from soils or rock, burning of coals, waste and other hazardous human activity enters a waterway, naturally occuring bacteria absorb it and convert it to organic mercury (methyl mercury). 

       This mercury then works its way up the food chain as large fish consume contaminated smaller fish that feed on bacteria and algae that take up methyl mercury as part of their food. Instead of dissolving or braking down, mercury accumulates at ever-increasing levels. Thus, predatory fish such as large tuna, swordfish, shark and mackarel can have mercury concentrations 10,000 times higher than those of their surrounding habitat.  Therefore, we need to be careful when choosing the fish that we are consuming.

A cartoon to lighten the day

The mercury level in different fishes

How Does Mercury harm your body??

     Once in the human body, mercury acts as a neurotoxin that will interfere with the brain and nervous system. Mercury pollution can be hazardous especially for pregnant women and young children.  Prenatal and infant mercury exposure may cause mental retardation, deafness and blindness.

       

Some Health hazards due to mercury pollution

       In Malaysia, the National Pharmaceutical Control Bureau (NPCB) requires the fish oil's mercury to be less than 0.5 ppm and  there is a centre ( SIRIM QAS International Sdn Bhd located in Shah Alam) that use Flameless Atomis Absorption Spectroscopy Technique to test for presence of mercury in the sample of fish oil : 

Some articles that you can read :
1)  Mercury level in commercial fish and shell fish
2) Mercury contamination in fish - http://www.nrdc.org/health/effects/mercury/effects.asp
3) What you need to know about mercury in Fish and Shellfish