Mercury has been known since ancient times and is commonly called quick silver or azogue. It is toxic in all three of its environmental forms: 1) elemental (liquid) mercury, 2) mercury salts and 3) organic mercury. This fact sheet will address the health issues related to elemental (liquid) mercury exposures.
What is elemental mercury and how is it used?
Elemental mercury is a shiny, silver-gray metal that is a liquid at room temperature. It can be found in thermometers, barometers, sphygmomanometers, dental amalgams, batteries, fluorescent lights and electrical switches. It also was commonly found in household latex paint prior to the early 1990s.
In some cultures, elemental mercury is used in rituals, love potions and folk medicines. Some of these activities may include swallowing mercury capsules, sprinkling it in homes around baby cribs, sprinkling it in vehicles, burning it in candles, wearing it in amulets and directly rubbing it on the skin.
How can people be exposed to elemental mercury?
Inhalation of elemental mercury vapor is the most common route of exposure. When liquid mercury is spilled or allowed to come in contact with air, it evaporates. Heating mercury by burning it or spilling it on a hot surface causes evaporation to occur at a much faster rate, making exposure much greater.
When a mercury-containing product breaks or when mercury is used in a cultural practice, it can lead to elevated levels of mercury vapor in the home. These levels can persist in the home for many months, especially if no one has properly removed the mercury.
Exposure also can occur through ingestion or dermal contact, but these routes have a much smaller degree of absorption and are rarely the cause of elemental mercury toxicity.
How is elemental mercury absorbed and metabolized?
When inhaled, about 80 percent of elemental mercury is absorbed into the blood stream through the alveoli. Because it is fat soluble, mercury readily crosses the blood-brain barrier and placenta. When ingested, only a small amount (0.01%) is absorbed through the gastrointestinal tract, making toxicity from this route rare. Dermal absorption also is negligible.
Once in the body, mercury is oxidized and eventually eliminated in the urine and feces. The half-life of elemental mercury in the body is approximately 60 days. Mercury accumulates in the kidneys, erythrocytes, bone marrow, liver, spleen, lungs, skin and hair. The most common effects of mercury exposure are manifested in the central nervous system.
What are the symptoms and health effects of elemental mercury exposure?
Acute exposure to mercury vapor leads to pulmonary and central nervous system effects. Inhalation of high levels of mercury vapor can cause the onset of symptoms such as cough, dyspnea, chest pain, nausea, vomiting, diarrhea, fever and a metallic taste in the mouth. These symptoms can progress to interstitial pneumonitis and pulmonary edema. Young children are at the greatest risk of developing pulmonary toxicity.
Chronic exposure to lower levels of mercury vapor causes effects to the central nervous system. Symptoms of chronic poisoning vary, but may include tremors, psychological changes, insomnia, loss of appetite, irritability, headache and short-term memory loss.
Direct contact with the skin can lead to dermatitis. A rare syndrome called acrodynia, or "pink's disease," can occur in children exposed to mercury vapor. Its symptoms include severe leg cramps, irritability and painful pink fingers with peeling hands. Few children exposed to mercury develop acrodynia.
What tests are available for elemental mercury exposure?
If elemental mercury exposure is suspected, several tests will show the amount of mercury in the body. If an acute exposure to mercury has occurred, a blood analysis will show mercury levels if performed within three days after the exposure. In adults, the background concentration of mercury is normally less than 1.5 micrograms per deciliter (µg/dL) of blood. A level greater than 5 µg/dL exceeds the threshold for symptoms of toxicity.
If a chronic, low-level exposure is suspected, a 24- hour urine specimen is the best measure of mercury. If a 24-hour specimen is not possible, the first morning void is the best substitute. For adults, the normal background concentration of mercury in urine is less than 20 micrograms per liter (µg/L).
What are some possible treatments?
For acute inhalation of mercury vapor, supportive care should be given to relieve and monitor pulmonary symptoms such as edema and pneumonitis. Chelation therapy may be necessary, with British anti-Lewisite (BAL), to decrease effects of mercury toxicity.
Ingestion of small amounts of mercury, such as the amount found in a thermometer, does not typically require treatment. In very rare cases, mercury can become trapped in the appendix or intestine and require surgical removal.
What if I am contacted about how to clean up a mercury spill?
The Illinois Department of Public Health (IDPH) assists in responding to mercury spills in homes. The amount of mercury from a typical broken thermometer would be considered a small spill. If more mercury than this is spilled, it would be considered a large spill. Some people save mercury from various sources and store the product in containers. This is dangerous because mercury may escape from broken or improperly sealed containers. Individuals may often be exposed without their knowledge.
Sampling conducted by IDPH in homes where small mercury spills have taken place has not shown large amounts of mercury in the air. High levels would not be expected unless the spill took place on a hot surface or into a device like a humidifier that blows liquids into the air. Spills from the breaking of a blood pressure device or larger sources can produce airborne levels high enough to cause serious poisoning and even death.
Persons involved in a large mercury spill should leave the area immediately. Contact your physician for possible treatment and testing. Contact IDPH for information concerning air testing and cleanup.
The following precautions should be taken if a small mercury spill occurs:
People not involved in the cleanup should leave the area.
Minimize tracking by removing shoes and clothing. Assume that the clothes of a child who played with mercury are contaminated. Place clothes in a sealed plastic bag and put them outside in a safe place until the household trash can be picked up. Plastic can be placed on the floors to minimize tracking.
Do NOT use a vacuum cleaner to clean up the spill. A vacuum cleaner will spread the mercury vapors and tiny droplets will settle throughout the area, increasing the spread of contamination and the chance of exposure.
Windows and doors in the area of the spill should be opened to ventilate the area.
Small amounts of mercury can be collected with adhesive tape or an eye dropper and stored in a sealed plastic container until disposal.
After all visible mercury has been collected, use a mercury cleanup kit to clean the spill area and work it into the cracks with a broom or brush. Do not add water. Materials in the mercury spill kit will rapidly bind to the remaining mercury and can be swept up with a broom and dustpan. Wash the area with trisodium phosphate detergent solution and rinse with water.
Contaminated carpeting should be removed and discarded, starting with the spill room.