Mercury is a neurotoxicant. Outbreaks of methylmercury poisonings have made it clear that adults, children, and developing fetuses are at risk from ingestion exposure to mercury. When mothers with no symptoms of nervous system damage gave birth to infants with severe disabilities, it became clear that the developing fetal nervous system is more vulnerable to methylmercury than is an adult's nervous system.
The most common way people are exposed to any form of mercury is by eating fish containing methylmercury. Other exposures include breaking products containing elemental mercury and using compounds that contain mercury.
The factors that determine how severe the health effects are from mercury exposure include:
- the chemical form of mercury;
- the dose;
- the age of the person exposed (the fetus is the most susceptible);
- the duration of exposure;
- the route of exposure -- inhalation, ingestion, dermal contact, etc.; and
- the health of the person exposed.