Why do some fish have mercury?
On land, the substance comes from rock erosion and volcanic activity. But human interventions, such as the burning of coal, are the biggest forms of contamination. Once released into the oceans, mercury is transformed into methylmercury by some bacteria.
The amount of the substance in certain fish varies according to size, diet, age and habitat. Predatory fish have the highest levels of the substance, as they absorb elements present in the body of their prey.
Fish with the highest mercury content
The UK Natural Resources Defense Council has produced two lists of the most mercury-contaminated fish and seafood. Divided into three parts, they list the most contaminated and those with the least amount. Find out what they are:
Fish with more mercury
• Shark
• Swordfish
• Needlefish
Fish with moderate indices
• Striped bass
• Large tent
• Lobster
• Monkfish
• Buffalo Fish
Fish, molluscs and crustaceans low in mercury
• Fish: chaputa, anchovies, catfish, salmon, sardines, tilapia, cod, abadejo and trout.
• Molluscs: oysters, squid and scallops.
• Crustaceans: shrimp.
Risks of mercury contamination
In excess, the substance causes complications in the eyes, kidneys, lungs and immune, digestive and nervous systems. However, moderate consumption does not cause health problems. The only reservations are in relation to pregnant women, women who are breastfeeding and children under 3 years old, according to Francisco Miguel Celdrán, nutritionist at the Catholic University of San Antonio de Murcia (Spain).
How to consume?
According to the UK National Health Service, the serving should not exceed 140 grams. The consumption of fish with mercury should be limited to a maximum of twice a month, explains Andrei Tchernitchin, president of the Department of the Environment at the Chilean School of Medicine.
Consumed correctly, fish are great allies. Find out how they help improve brain health!
Text written by Sumaia de Santana Salgado from the Eu Sem Fronteiras Team.
