Fish contain mercury primarily because they absorb it from their surrounding environment and the food they eat.
How Fish Accumulate Mercury
Fish are exposed to mercury present in streams and oceans. As they feed on smaller organisms or absorb substances from the water, they take up mercury from streams and oceans as they feed. This process is how the element enters their bodies.
The Form of Mercury in Fish
The mercury found in fish is predominantly in a specific form called methylmercury. This is an organic compound of mercury and is considered the more toxic, methylmercury form. It's particularly concerning because it can build up in the tissues of living organisms, including fish.
Where Mercury Is Stored in Fish
Once absorbed, methylmercury doesn't easily pass out of the fish's body. Instead, it binds to proteins in the body (such as proteins found in muscle tissue). This is significant because the muscle tissue is the part of the fish most commonly consumed by humans. As fish grow older and larger, they can accumulate higher levels of mercury in their muscles.
What Doesn't Remove Mercury from Fish
It's important to understand that removing mercury from fish is difficult. The reference states that food processing, preparation and cooking techniques don't significantly reduce the amount of mercury in fish. This means methods like baking, frying, or boiling will not remove the mercury that has already bound to the fish's tissues.
In summary:
- Fish absorb mercury from water and food.
- The mercury is mainly in the toxic methylmercury form.
- Methylmercury binds to proteins, concentrating in muscle tissue.
- Cooking and processing methods do not significantly reduce mercury levels.
