Mercury in Canned Fish

Mercury is an element in the periodic table that is very carcinogenic. For many, many years it was the metal used in thermometers. But, when a thermometer broke, the mercury would spill out and could cause illness for those who came in contact with it.

There is a type of mercury that is found in canned fish and some fresh fish. It is called methyl mercury. Fish pick it up from water pollution. Factories and mines have this type of mercury in the smoke that is given off from the processes going on inside. Even volcanic activity can produce this type of mercury.

Over time, this pollution that enters the air eventually makes it into the lakes, rivers and streams. The amount of mercury and methyl mercury in the water itself is minimal and within standards. The problem comes in when that mercury enters the food chain.

Here is how it works. The algae in the water absorb the methyl mercury. Other organisms in the water nibble on this algae or live within it. Small fish eat the smaller organisms and absorb the mercury compound. Can you see where we are going with this?

Each successive level of the food chain consumes a little more of the mercury into their bodies. The mercury is stored in the muscle of the fish, which is what we eat. Unfortunately, fish fall prey to what we term “bioaccumulation.” More mercury is stored in the bodies of the fish higher in the food chain that live longer.

Mercury is excreted slowly from the bodies of fish. If you eat canned tuna for example, you will get more methyl mercury than if you were to eat an oyster or a smaller fish.

While seafood and fish supply plenty of needed vitamins and minerals to the body, they can also present a danger. For this reason, pregnant women are advised not to eat much fish and seafood during their pregnancy. The presence of mercury in the body can be toxic to unborn fetuses and also little children.

It is recommended that a pregnant woman eat less than six ounces of canned fish like tuna per week because of the potential mercury content. Fish that are on the “Do Not Eat” list are larger ones like shark, mahi mahi, swordfish, and king mackerel. Instead try smaller fish and other seafood like shrimp or salmon.