Health Risks Associated with Mercury
Mercury exists in several forms.  The metallic form is the familiar liquid metal used in thermometers.  The ore cinnabar contains the common inorganic form.  The most common organic form is methylmercury.  A person can be exposed to mercury from breathing in contaminated air, skin contact, or eating contaminated foods.  For most individuals however, the primary exposure pathway to mercury is through eating fish.  Human exposure to methylmercury through the consumption of contaminated fish is a global concern.  Exposure through diet has increased the body burden of methylmercury in animal and human populations.   A spectrum of adverse health effects has been observed following methylmercury exposure.  The severity of effects depends on a number of factors which include: 

• The chemical form of mercury,
• The amount of exposure,
• The duration of exposure,
• The route of exposure – inhalation, ingestion, dermal contact, and
• The age and health of the person exposed
   

Most at Risk

Infant and Children’s Health

Mercury is known to cause irreversible damage to the developing nervous system.  Mercury in a pregnant woman’s body can be passed to her developing fetus.  Fetuses exposed to mercury in utero are susceptible to the health effects from mercury which may lead to difficulties in learning, memory, vision, and hearing.  Because of the potential adverse impacts on the developing brain, our greatest concern is exposure to the fetus, infant, or young child during the period of rapid brain growth. Therefore, most at risk are women who are pregnant, may become pregnant, nursing, and young children.  Key issues influencing the severity of effect include the amount and form of mercury and the age of development.  Mothers who eat fish contaminated with high levels of mercury put their babies at greater risk for damage to their central nervous systems.  EPA has recently estimated that as many as 400,000 babies born each year in the U.S. are at risk for neurodevelopment damage due to consumption of mercury contaminated fish.

Adult Health Risk
Other health effects have been seen with higher exposure to mercury not only in children but adults as well.  Common effects include various neurological dysfunctions such as tremors, changes in vision, loss of hearing, muscle coordination, loss of sensation, and difficulties with memory.  At higher exposures, effects on the kidneys, lungs, and digestive system have been noted.  These effects generally are associated with high level occupational or accidental poisonings and not fish consumption.   Furthermore, concern over possible adverse cardiovascular effects to the general population related to fish consumption has also been raised by recent health studies.  National and international research efforts are currently underway to address this concern.