Elemental mercury is a silvery, liquid metal often found in older household items like thermometers and thermostats. When this substance spills, it is dangerous. The primary hazard comes not from touching the liquid metal, but from the invisible, toxic vapor it continuously releases into the air at normal room temperatures. This inhalation risk means even small household spills require immediate and careful attention.
The Specific Danger of Spilled Elemental Mercury
Spilled elemental mercury, also known as metallic mercury, begins to evaporate immediately, even without a heat source. This process releases a colorless and odorless vapor that quickly builds up in enclosed spaces. Since the vapor is impossible to detect without specialized equipment, people can breathe it in unknowingly.
The liquid metal is not absorbed well through the skin or the digestive tract; therefore, the real threat is the gas it produces. When mercury breaks apart into tiny beads upon impact, the total surface area increases significantly. This scattering accelerates the rate of vaporization, spreading the toxic vapor throughout the environment.
Health Effects of Mercury Vapor Exposure
Once inhaled, approximately 80% of the elemental mercury vapor is absorbed through the lungs and enters the bloodstream. It is then transported throughout the body, including across the blood-brain barrier, which protects the central nervous system. This ability to penetrate the brain is why elemental mercury is classified as a neurotoxin.
Acute, or short-term, exposure to high concentrations of the vapor can cause immediate symptoms affecting the respiratory and gastrointestinal systems. These effects may include a metallic taste, nausea, vomiting, chest tightness, and difficulty breathing. In severe cases, exposure can lead to lung inflammation and respiratory distress.
Chronic exposure results from breathing lower levels of vapor over weeks or months, primarily affecting the nervous system and the kidneys. Neurological symptoms often begin subtly, presenting as insomnia, tremors, and emotional changes like irritability or excessive shyness. As the metal accumulates, it can cause long-term issues such as memory loss, reduced motor skills, and permanent kidney damage.
Immediate Steps for Safe Cleanup and Containment
The first step following any spill is to immediately evacuate all people and pets from the affected room. Close doors to isolate the area, but simultaneously open exterior windows for ventilation. Crucially, turn off central air conditioning or heating systems, as these can spread the mercury vapor throughout the building.
Never use a vacuum cleaner, mop, or broom to collect the spilled liquid. A vacuum will heat the mercury and aerosolize the droplets, dramatically increasing the vapor concentration in the air. Brooms and mops break the liquid metal into smaller beads, which makes cleanup nearly impossible and increases the surface area for vaporization.
Cleanup should only be attempted for very small spills, such as from a single thermometer. The person conducting the cleanup must remove all metal jewelry and wear non-porous gloves. Use a flashlight held at an angle to locate the tiny, reflective beads of mercury, which often scatter into crevices. Carefully use a stiff piece of paper or cardboard to push the droplets together, then use an eyedropper to collect them.
All collected mercury beads and cleanup materials must be placed into an airtight plastic container or a heavy-duty, sealable plastic bag. After collection, sticky tape, such as duct tape, can be used to pick up any remaining minute particles from hard surfaces. The final step is to contact the local household hazardous waste facility or health department for proper disposal information. Mercury should never be poured down a drain or thrown into the regular trash.
Distinguishing Elemental Mercury from Other Forms
Mercury exists in three main forms, and a spill of elemental mercury presents a different risk profile than the other types. Elemental mercury, the liquid metal, is dangerous when its vapor is inhaled, targeting the brain and nervous system. This is the form typically encountered in spills from household devices.
Inorganic mercury compounds, such as mercury salts, are often found in industrial products. They are corrosive to tissues if ingested, causing damage primarily to the kidneys and gastrointestinal tract. These salts are not volatile and do not easily cross the blood-brain barrier.
Organic mercury, primarily methylmercury, is formed in the environment and bioaccumulates in the tissues of fish and shellfish. When consumed, methylmercury is a neurotoxin, posing a severe risk to the developing nervous system of fetuses and young children. While a spill is an immediate inhalation hazard, organic mercury is the more common dietary concern for the general population.