Mercury Exposure Facts

Common Exposures to Mercury

The main way that people are exposed to mercury is by eating fish and shellfish that have high levels of methylmercury, a highly toxic form of mercury, in their tissues. A less common way people are exposed to mercury is breathing mercury vapor. This can happen when mercury is released from a mercury-containing product or device that breaks. Mercury-containing Amalgam fillings, especially when older and brittle, are also a cause of mercury exposure. Through chewing or grinding teeth, the less toxic elemental mercury can be released. When entering the digestive tract, the action of putrefactive bacteria can change elemental mercury to the highly toxic methylmercury.

Health Effects Associated with Mercury Exposure

Mercury exposure at high levels can harm the brain, heart, kidneys, lungs, and immune system of people of all ages. High levels of methylmercury in the bloodstream of babies developing in the womb and young children may harm their developing nervous systems, affecting their ability to think and learn.

Mercury is a known neurotoxin. Exposure symptoms depend on a variety of factors, including:

  • The form of mercury (for example, methylmercury or ;elemental (metallic) mercury);
  • The amount of mercury in the exposure;
  • The age of the person exposed (unborn infants are the most vulnerable);
  • How long the exposure lasts;
  • How the person is exposed - breathing, eating, skin contact, etc.;

The effects of mercury exposure can be very severe, subtle, or may not occur at all, depending on the factors above.

Possible symptoms of methylmercury poisoning may include:
  • Loss of peripheral vision;
  • "Pins and needles" feelings, usually in the hands, feet, and around the mouth;
  • Lack of coordination of movements;
  • Impairment of speech, hearing, walking; and/or
  • Muscle weakness

Elemental mercury: People may be exposed when they breathe air containing elemental mercury vapors. Vapors may be present in such workplaces as dental offices, smelting operations, and locations where mercury has been spilled or released. 

Mercury vapors cause health effects when inhaled. Symptoms of prolonged and/or acute exposures to mercury vapor include:
  • Tremors;
  • Emotional changes (such as mood swings, irritability, nervousness, excessive shyness);
  • Insomnia;
  • Neuromuscular changes (such as weakness, muscle atrophy, twitching);
  • Headaches;
  • Disturbances in sensations;
  • Changes in nerve responses; and/or
  • Poor performance on tests of mental function.
  • Higher exposures may also cause kidney effects, respiratory failure and death.

Effects on Infants and Children

Infants in the womb can be exposed to methylmercury when their mothers eat fish and shellfish that contain methylmercury or are exposed to mercury fumes through dental work. This exposure can adversely affect unborn infants' growing brains and nervous systems, affecting cognitive development, memory, attention, language, fine motor skills, and visual spatial skills.

Diagnosis of mercury exposure:

Today's focus on the health impact of exposure to mercury is more on chronic, low or moderate grade exposure - albeit a topic of great controversy -, not high concentration exposure by methylmercury, which caused Minamata disease.

  • Blood mercury tests will determine if a recent exposure happened, and a morning urine or 24h-urine test will further support the diagnosis. According to CDC scientists, both blood and urine mercury levels tend to increase with age.
  • A Provocation test with a chelating agent such as DMPS will release mercury from bodily deposits such as the kidneys and other organ systems.
  • Hair analysis determines if chronic exposure or exposure that happened some time ago resulted in tissue storage.
  • Saliva testing can indicate if mercury is released from dental amalgam. Saliva testing does not reveal a systemic exposure
  • Fecal testing will indicate if mercury ingested from food or released through amalgam has passed through the gastrointestinal tract. Fecal testing does not indicate a systemic exposure.


  • CDC. Mercury Factsheet. Mercury Factsheet | National Biomonitoring Program | CDC
  • Ye BJ, Kim BG, Jeon MJ, Kim SY, Kim HC, Jang TW, Chae HJ, Choi WJ, Ha MN, Hong YS. Evaluation of mercury exposure level, clinical diagnosis and treatment for mercury intoxication. Ann Occup Environ Med. 2016 Jan 22;28:5. doi: 10.1186/s40557-015-0086-8. PMID: 26807265; PMCID: PMC4724159.