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Frequently Asked Questions

How would I be exposed to mercury?

How does mercury go from a mother to an unborn baby?

How does mercury affect children?

How can mercury affect my health?

How does mercury get into fish?

Should I eat fish when I'm pregnant?

Should I breastfeed my baby if I eat fish?

Should my children eat fish?

Does it make a difference what kind of canned tuna I eat?

Can I be tested for mercury exposure?

Does mercury cause cancer?

What is the difference between mercury and methylmercury?

By cooking fish longer, can you get rid of the mercury?

What about contaminants other than mercury?

What about salmon: Is it safe to eat?

What about fish sticks?

Should I eat meat instead of fish?

What can be done to keep mercury from getting into fish?

How would I be exposed to mercury?
The Centers for Disease Control and Prevention (CDC) published data indicating that most of the exposure in young children and women of childbearing age in the United States happens as a result of eating fish contaminated with methylmercury. Other sources of possible mercury exposure include:

  • Breathing mercury vapors in air from spills, incinerators, and industries that burn mercury-containing fuels.

  • Skin contact with mercury or breathing contaminated air in workplaces that use mercury (such as dental, medical, chemical or other industries). Practicing rituals that include the use of mercury.
  • Release of mercury from dental work and medical treatments.
  • Consuming fish.
  • Find mercury in your home.

How does mercury go from a mother to an unborn baby?
During pregnancy, mercury can be passed from a mother to her unborn child through the placenta. It can also pass to a nursing infant through breast milk.

How does mercury affect children?
Small doses can impair the brain and the developing nervous system.  Babies born to mothers who have a lot of mercury in their bodies may develop more slowly and have problems learning.  The effects of in utero exposure to mercury can take months or years to appear.  Health experts believe infants and children are more susceptible to the effects of methylmercury because their nervous systems continue developing until adolescence. 

How can mercury affect health?
Health problems caused by mercury are most severe for a developing fetus and for young children. Babies whose mothers, during pregnancy, eat fish contaminated with large amounts of mercury are at greater risk for changes in their nervous systems, and possibly in their heart or blood vessels. Nervous system changes can affect their baby's ability to learn.  In adults, methylmercury can lead to problems of the central nervous system and possible adverse effects on the cardiovascular system.

Based on human and animal data, the International Agency for Research on Cancer (IARC) and the Environmental Protection Agency (EPA) have classified methylmercury as a "possible" human carcinogen. This means that mercury has been found to produce cancer in two animal species, but that evidence is not adequate to say that it causes cancer in humans.

How does mercury get into fish?
Mercury contamination is a worldwide problem. It can come from many sources. It occurs naturally in the environment in rocks, soils, water and air. Products containing mercury which are thrown in the garbage or washed down sinks and drains end up in landfills, incinerators, or sewage treatment facilities. Mercury from these products can leach into the ground and groundwater. Mercury may be directly released into the environment, or through combustion (burning) activities, from coal-fired power plants, where it is released in fine particles in the air that fall to the earth in rain or snow. Once released into the environment, mercury eventually ends up in water and settles into sediments. Bacteria in the water converts the inorganic mercury into methylmercury, an organic mercury compound. These bacteria are eaten by plankton and other small creatures, which in turn are eaten by small fish, then larger fish. Mercury does not easily leave the body of an organism, so the amount of mercury builds up in species as they go up the food chain in a process called bioaccumulation. Predatory fish, which sit higher up on the food chain and are long-lived, can accumulate hundreds of thousands to millions of times the concentration of mercury that originally entered the water. As people eat fish with mercury, the mercury is transferred to humans and builds up in the body.   

Should I eat fish when I'm pregnant?
Yes
, in fact this is a very important time to eat fish as recommended in our Healthy Fish Eating Guide and Checklist. Remember to avoid any fish high in mercury. Fish are full of Omega-3 fatty acids, vitamins, and minerals that are very important to your child's development. Health Benefits of Fish

Should I breastfeed my baby if I eat fish?
Yes,
breastfeeding provides your baby with many health benefits that will last a lifetime. The benefits of breastfeeding outweigh any risks that your baby may receive through breast milk. The key is to choose fish low in mercury and other contaminants so you and your child gain the benefits of the Omega-3 fatty acids that only fish can provide.

Should my children eat fish?
Yes
, serve children a variety of fish that are low in mercury and other contaminants as recommend in our Healthy Fish Eating Guide. Fish sticks and fast food fish sandwiches are usually made from fish low in contaminants.

Does it make a difference what kind of canned tuna I eat?
Yes.
A recent study conducted by Washington Department of Health, showed that mercury levels in canned light tuna were three times lower than those in canned white (albacore) tuna. Albacore tuna is also called white tuna. Read the label on canned tuna and choose “light tuna”. There does not appear to be much difference in mercury levels between solid and chunk tuna, or between tuna packed in water versus oil. Statewide Advisory for Mercury.

Can I be tested for mercury exposure?
Yes. There are reliable and accurate ways to measure mercury in your body. These tests involve taking blood, urine, or hair samples, and must be performed in a doctor's office or in a health clinic. Most tests do not determine the form of mercury to which you were exposed. Hair analysis is considered useful for exposures to methylmercury, and may yield results for exposures having occurred within the past year. Consult your health care provider if you would like to learn more about testing for mercury exposure.

Does mercury cause cancer?
Based on human and animal data, the International Agency for Research on Cancer (IARC) and the Environmental Protection Agency (EPA) have classified methylmercury as a "possible" human carcinogen. This means that mercury has been found to produce cancer in two animal species, but that evidence is not adequate to say that it causes cancer in humans.

What is the difference between mercury and methylmercury?
Mercury is a metal that has several forms. Most commonly, people recognize mercury as the shiny, silver-white fluid in thermometers. Methylmercury is the kind of mercury that gets into fish. In water, the inorganic form of mercury is converted to methylmercury by bacteria or chemical reactions. Methylmercury is produced when a carbon with three hydrogen molecules attached to it (called a methyl group) is united with the element mercury.

By cooking fish longer, can you get rid of the mercury?
Mercury is tightly bound to proteins in all fish tissue including muscle. There is no method of cooking or cleaning fish that will reduce the amount of mercury in a meal. 

What about contaminants other than mercury?
Unlike mercury, the amounts of contaminants like PCBs and many pesticides are stored mostly in the fat of fish. Preparing fish in ways that reduce the fat can also reduce these other contaminants. Cut off the skin and most available fat before cooking fish. Then broil, grill, or bake it on a rack so the fat drips off the fish. Do not use the drippings for sauces or gravies.

What about salmon: Is it safe to eat?
Most species of salmon tend to have very low levels of mercury and are safe to eat. See our Healthy Fish Eating Guide for smart salmon choices.

What about fish sticks?
Yes, you and your children can eat fish sticks. Most fish sticks are made from pollock caught off the coast of Alaska. Pollock is very low in contaminants.

Should I eat meat instead of fish?
There are contaminants in all foods, avoiding fish and replacing it with other protein sources like meat or poultry will not eliminate your exposure to contaminants. By choosing fish wisely, you and your family can greatly reduce your exposure to contaminants while at the same time gaining the health benefits from fish.  DOH recommends that you follow the guidelines recommended, which include eating a variety of fish and shellfish as a part of a healthy, balanced diet.

What can be done to keep mercury from getting into fish?
Choosing to eat fish low in mercury is an important strategy to protect health. The long-term strategy for reducing exposure to mercury is to lower concentrations of methylmercury in fish by limiting mercury releases into the atmosphere from burning mercury-containing fuel and waste and from other industrial processes. Contaminants, like mercury, released into the atmosphere today, may end up on our dinner table tomorrow. There are many actions you can take to reduce mercury in the environment. 

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Last Update: 02/12/2008