One of our protein sources is fish, especially tuna. It contains high quality protein and all necessary amino acids essential for our health, and unlike most protein sources, fish contain only a tiny amount of fat. As protein source, fish do not cause deforestation and water guzzling like do beef and soybean their competitors. Fish would be an ideal protein diet, if only they are not contaminated with mercury.
Yes, sadly, almost all fish and shellfish contain residue of methylmercury that 44 states in the U.S. issued fish consumption advisories and warning on the fish consumption, especially tuna fish. Mercury pollution is reported to have contaminated 12 million acres of lakes, estuaries and 30% wetlands and 473,000 miles of streams, rivers and coasts across the United States. Contaminated fish has become a serious problem today.
How fish get contaminated with mercury:
Mercury occurs naturally in the environment and can also be tossed into the air through power generation plant and industrial pollution. Once released into the air, mercury residue can travel hundreds of miles or falls from the air to the land or water bodies such as ocean, rivers, streams and lakes. Once it enters waterway, it will be absorbed by naturally occurring bacteria which converted it to a form known as methylmercury. Fish that live on this contaminated water will be mercury-laden as they absorb the methylmercury.
Mercury Content in Fish:
Methylmercury builds up more in some types of fish than others, depending on what the fish consume and the life time of the fish. The longer (normally the larger) the fish live, the more mercury accumulated. Another reason why larger fish are more mercury-laden is because when they eat smaller contaminated fish, the mercury accumulates at ever-increasing levels. Among these large fish that have the greatest mercury content are swordfish, large tuna, shark, tilefish and king mackerel. Those fish are considered to be the most contaminated fish. The level of water contamination also affect to the level of mercury content on fish.
The effects from consuming contaminated fish and shellfish.
For most adults, mercury’s risk from consuming contaminated fish and shellfish will not cause a serious problem as it is to an unborn babies or young children. Therefore those with the most vulnerable to mercury’s harmful effects are fetus, infant, young children under seven year, pregnant women, women planning to become pregnant and nursing mothers. Harvard School of Public Health warned in a study published in the Journal of Pediatrics, fetuses and young children exposed to methylmercury can suffer permanent damage to the heart as well as impaired brain growth. Once mercury enters a small child’s body, it acts as a neurotoxin, interfering with the brain and nervous system. . In low doses mercury can affect a child’s development, delaying talking and walking, learning disabilities and shortening attention span. A child’s brain is still developing within the first seven years and it will rapidly absorbing nutrients. Prenatal and infant mercury exposure can result metal retardation, deafness, blindness and cerebral palsy. According to a study issued by Environmental Health Perspectives in the April 2004, in 1999-2000, more than 300,000 newborns in the U.S. may have been exposed to “unacceptable levels” of mercury through their mothers’ toxic fish consumption.
Although reported not to affect seriously in adults, mercury poisoning can adversely affect fertility and blood pressure regulation and can cause memory loss, tremors, vision loss and numbness of the fingers and toes. Exposure to mercury may also lead to heart disease.
The effects from consuming contaminated fish and shellfish depend on the amount of fish and shellfish consumed and the levels of mercury in the fish and shellfish. It is advised that those who are most vulnerable to mercury’s effects restrict certain fish from their diet, especially large fish as it is the most contaminated fish.
Fish is an eco alternative of protein diet. It also contains important nutritions needed for our health care. There is no serious effect of mercury content for adults; and women and children should consume fish too in proper portion. Choose your selection here.