The main causes of mercury exposure in humans are the consumption of fish and shellfish followed by inhalation of mercury vapor, according to the Environmental Protection Agency. The agency notes that outbreaks of mercury poisoning are linked more closely to ingestion than inhalation of mercury.
Every year, the Environmental Protection Agency works with the Food and Drug Administration to release guidelines on the safe eating of fish and shellfish as well as fish advisories for people of all ages, according to the EPA. To reduce exposure to mercury vapor, in 2010 the EPA began developing emissions standards with power plants. Other less-common situations that can result in exposure to mercury include the release of mercury from medical or dental procedures, improper disposal of outdated medications containing mercury, or through skin contact during workplace procedures or rituals that include the metal, according to Agency for Toxic Substances and Disease Registry.
Fetuses, infants and very young children are most-susceptible to the toxic effects of mercury, states the Agency for Toxic Substances and Disease Registry. This group can experience brain damage, blindness, seizures, delayed mental development and incoordination. Other possible effects include an inability to speak, kidney damage, and disorders of the digestive or nervous systems. Short-term exposure to mercury vapors can result in lung damage, eye irritation, gastrointestinal issues, skin rashes, and elevations of heart rate and blood pressure in people of all age groups.