Two types of fish contain a lot of mercury you need to know

Fish and seafood are familiar and nutritious dishes for humans. However, you should be aware when using some types containing high levels of mercury.

A study by Dartmouth scientists, USA, found that people who ate fish and seafood on a regular basis were twice as likely to have motor neuron disease (Motor Neurone Disease - MND). eat or eat less.

Scientists surveyed 518 people about the number of seafood they consumed in a year, resulting in 294 people suffering from MND. They also measured mercury levels by taking pedicure samples from the survey participants.

Long-term exposure to mercury is calculated based on how often different types of seafood are eaten, including those with low mercury content such as sardines and salmon.

Sharks and swordfish are two species of seafood that contain high mercury.(Photo: Getty Images).

Swordfish and sharks contain very high levels of mercury, which can increase the risk of MND and amyotrophic lateral sclerosis (Amyotrophic Lateral Sclerosis - ALS) . Serious damage to the brain and can lead to death.

Lead researcher Dr Elijah Stommel said: "For many people, fish is part of a healthy diet. But in the long run, the amount of mercury in fish that accumulates gradually will cause seriously affects our health ".

Mercury is harmful to humans when exposed to air and inhaled. They exist in organic form (methyl mercury) that can enter the body when people eat some fish, especially large fish such as sharks, swordfish, and tuna. Swordfish and sharks are thought to have the most mercury , because they are at the top of the food chain. They eat smaller fish, so the amount of mercury accumulated is increasing.

Mercury is a rare metal that occurs naturally in the earth's crust. They are dispersed into the environment mainly due to human activities, such as coal-fired thermal power plants, waste incinerators, mining, coal burning for heating and cooking.

Experts recommend adults should only eat shark meat or swordfish once a week. Children and pregnant women should not eat these fish.