Understanding Mercury Poisoning (2024)

Small amounts of mercury present in everyday foods and products may not affect your health. Too much mercury, however, can be poisonous.

Mercury poisoning refers to toxicity from mercury consumption. Mercury is a type of toxic metal that we can come into contact with in a variety of ways. This may include consuming certain types of seafood and wearing certain types of jewelry.

The most common cause of mercury poisoning is from consuming too much methylmercury or organic mercury, which is linked to eating seafood.

Mercury itself is naturally occurring, but the amounts in the environment have been on the rise due to industrialization. The metal can make its way into soil and water, and eventually into animals like fish.

Consuming foods with mercury is a common cause of this type of poisoning. Children and pregnant people are the more vulnerable to the effects of mercury poisoning. You can help prevent toxicity by limiting your exposure to this potentially dangerous metal.

Mercury is most notable for its neurological effects. In general, the Food and Drug Administration (FDA) says that too much mercury may cause:

• anxiety
• depression
• irritability
• memory problems
• numbness of the hands, feet, or mouth
• pathologic shyness
• tremors

More often, mercury poisoning builds up over time, along with its effects.

But, a sudden onset of any of these symptoms could be a sign of acute toxicity. Call a healthcare professional right away if you suspect mercury poisoning.

Mercury poisoning symptoms in adults

Adults with advanced mercury poisoning might experience:

• hearing and speech difficulties
• lack of coordination
• muscle weakness
• nerve loss in hands and face
• trouble walking
• vision changes

Mercury poisoning symptoms in children and infants

Mercury poisoning can also disrupt fetal and early childhood development. Infants and young children who’ve been exposed to high levels of mercury may have delays in:

• cognition
• fine motor skills
• speech and language development
• visual-spatial awareness

People who are pregnant or nursing should avoid eating fish with high levels of mercury. Mercury can be passed to a developing fetus in the womb or to a child through breast milk.

High amounts of mercury can lead to long-term and sometimes permanent neurological changes. The dangers are especially notable in young children who are still developing.

Mercury exposure can lead to developmental problems in the brain, which can also affect physical functions such as motor skills. Some children who are exposed to mercury at a young age may develop learning disabilities, according to the Environmental Defense Fund.

Adults with mercury poisoning may have:

• permanent brain damage
• permanent kidney damage
• circulatory failure

Mercury poisoning from fish and seafood

Methylmercury (organic mercury) poisoning is largely linked to eating seafood, mainly fish. Toxicity from fish has two causes:

• eating certain types of mercury-containing fish
• eating too much fish

Fish get mercury from the water they live in. All types of fish contain some amount of mercury. Larger types of fish can have higher amounts of mercury because they prey on other fish that contain mercury too. The concentration of mercury concentrations in fish and seafood may be 1 to 10 million times that of the concentration in the surrounding water.

Fish with the highest levels of mercury can include:

• sharks
• swordfish
• bigeye tuna
• marlin
• tilefish
• king mackerel
• orange roughy

It’s also possible to develop mercury poisoning from eating too much seafood, even if the varieties have lower levels of mercury.

The FDA states that in small amounts, certain types of fish with lower mercury levels may be okay for adults to eat once or twice per week.

Fish and seafood with the lowest mercury levels can include:

Fish and seafood with moderate levels of mercury can include:

Though these options contain less mercury, you’ll want to take care in how much you eat.

According to the FDA, if you’re pregnant or breastfeeding, you should restrict your consumption to 2 to 3 servings of 4 ounces of fish and seafood with the lowest mercury levels per week, or one 4-ounce serving of fish and seafood with moderate mercury levels per week.

A 2020 study found that, for study participants, eating fish less than one time a week had little effect. However, participants who ate fish two or more times a week had dangerously high levels of fetal mercury exposure.

The FDA also recommends that children ages 11 and under eat 2 servings or less per week of fish or seafood with the lowest mercury levels. Serving sizes by age can vary. These serving sizes include:

• Ages 1 to 3: 1 ounce
• Ages 4 to 7: 2 ounces
• Ages 8 to 10: 3 ounces
• Age 11: 4 ounces

Certain states, territories, and tribes in the US may also have specific advisories about water sources where fish are caught that may be contaminated with mercury. It’s best to be aware of these advisories before consuming fish caught by yourself, your family, or your friends.

Other causes of mercury poisoning can be environmental or from exposure to other forms of this metal. These can include:

• broken thermometers that contain mercury
• dental fillings with amalgam
• certain types of jewelry
• mining for gold and household gold extraction
• certain skin care products that may have been purchased abroad or marketed illegally in the U.S., according to the FDA
• exposure to toxic air in industrialized communities

Mercury poisoning is diagnosed with a physical exam and other tests. These tests may include:

• chest radiograph
• urinalysis
• blood tests, such as serum mercury levels, a complete blood count (CBC) and a metabolic panel

A healthcare professional may ask about your symptoms and when they started. They may also ask you about your dietary choices and other lifestyle habits.

If mercury poisoning is suspected, doctors may request additional blood and urine tests to measure the mercury levels in your body.

Depending on the level of mercury poisoning, treatment may involve decontamination.

You may be placed on an IV or given oxygen.

If your mercury levels reach a certain point, a healthcare professional may have you do chelation therapy. Chelating agents are drugs that remove the metal from your organs and help your body dispose of them.

Other attempts to reduce the amount of mercury in your body and gastrointestinal (GI) tract may be performed. These may involve:

• charcoal
• whole bowel irrigation
• dialysis
• transfusions

Long term, you may need continuing treatment to manage the effects of mercury poisoning, such as neurological effects.

There’s no cure for mercury poisoning. The best way to treat mercury poisoning is to limit your exposure to the metal. If you eat a lot of mercury-containing seafood, a doctor may caution you to stop immediately.

If toxicity is linked to your environment or workplace, you might need to take steps to remove yourself from the area to prevent further effects of poisoning.

When detected early, mercury poisoning can be halted. However, neurological effects from mercury toxicity are often permanent.

The best way to prevent dietary mercury poisoning is to take care with the amount and types of seafood that you eat. You can also:

• Limit your intake of larger fish.
• Avoid fish containing high levels of mercury if you’re pregnant or nursing.
• Follow fish and seafood serving guidelines for children.
• Be choosy with your sushi choices. Many popular sushi rolls are made with mercury-containing fish.
• Be on the lookout for fish advisories in your area. This is especially useful if you fish for your own seafood.
• Take a blood or urine mercury test before trying to conceive.
• Wash your hands right away if you think you’ve been exposed to other forms of mercury.
• Manage household spills of mercury.
• Avoid activities with known mercury exposure risk, such as home gold extraction.

Mercury poisoning can occur if too much mercury enters the body.

You can potentially get mercury poisoning by eating certain types of seafood and wearing certain types of jewelry.

To help prevent ingesting toxic amounts of mercury, follow the FDA guidelines for seafood consumption. Some types of seafood are higher in mercury than others.