Mercury and Women's Health Fact Sheet

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What is mercury?
Is mercury harmful?
How does mercury get into the environment?
Is there a risk from mercury by eating fish and shellfish?

What is mercury?

Mercury is a naturally occurring element that can be found in air, water, soil, and rocks. Mercury has historically served many useful purposes. It is used in some types of dental amalgams, some blood pressure monitoring devices, some batteries, fluorescent lamps, thermostats, barometers and thermometers.

Is mercury harmful?

Mercury can be harmful to humans if they are exposed to significant amounts over a long enough period of time. The age of the individual, the health of the individual, the type of exposure (eating breathing, injecting, or touching) are also factors that can impact the effect of mercury on one's health. Because mercury is so widespread in the environment, most people have at least trace amounts in their bodies. The mercury in dental amalgams poses no harm.

How does mercury get into the environment?

Mercury vapors are released into the atmosphere by coal burning power plants, during the burning of medical waste, and during chlorine production. Mercury also enters the atmosphere as a result of volcanic eruptions. When mercury falls from the air or runs off the ground into the water, certain microorganisms in soils and sediments convert it into methylmercury, a toxic from of mercury that is readily absorbed through the small intestines. Small organisms take up methylmercury as they feed. When animals higher up the food chain eat the smaller ones they also take in the methylmercury. As a result nearly all fish and shellfish contain traces of methylmercury. However, larger predator fish that have lived longer have the highest levels of methylmercury because they've had more time to accumulate it. These fish include swordfish, sharks, tilefish, and king mackerel.

Is there a risk from mercury by eating fish and shellfish?

For most people, the risk from mercury by eating fish and shellfish is not a health concern. In fact, the many nutritional benefits of fish and shellfish make them an important part of a healthy diet for all individuals, especially expecting and new mothers and young children. Still, some fish and shellfish contain higher levels of mercury that may harm an unborn baby or young child's developing nervous system.

In 2004 FDA and EPA jointly published an advisory on mercury in seafood, that, if followed, should keep an individual's mercury consumption below levels that have been shown to cause harm. By adhering to this advisory, parents can be confident of reducing their unborn or young child's exposure to the harmful effects of mercury, while at the same time maintaining a healthy diet that includes the nutritional benefits of fish and shellfish. This advisory is intended for women who may become pregnant, pregnant mothers, nursing mothers, and young children.