Mercury Poisoning

Definition

Demographics

• were minimal or nontoxic
• occurred in homes or schools
• involved broken thermometers

Description

• Elemental or metallic mercury, also called quicksilver, is a shiny, silvery metal that is a liquid at room temperature, but is easily vaporized to a colorless, odorless gas that can be inhaled. Elemental mercury is released into the air by natural processes such as volcanic activity and by various industrial processes, especially coal-burning power plants. It is extremely poisonous and 79%–80% of inhaled mercury vapor is absorbed by the lungs. In the past, mercury vapors poisoned hat makers—hence the Mad Hatter of Alice in Wonderland. Elemental mercury is used in thermometers, compact fluorescent light bulbs (CFLs), electrical switches, and older-type dental fillings.
• Inorganic mercury compounds include mercuric oxide (HgO) and mercuric salts, such as mercuric chloride (HgCl₂). These compounds are usually white powders or crystals. Inorganic mercury is used in many industries and can be found in some skin ointments and creams, disinfectants, fungicides, folk medicines, red cinnabar pigment, and button batteries that power small electronics.
• Organic mercury compounds are carbon-containing substances, such as methylmercury, ethylmercury, and phenylmercury. Bacteria in soil and water convert inorganic mercury in the environment into methylmercury, which accumulates in fish. Larger and older fish generally have the highest levels of methylmercury. In some parts of the world, organic mercury is used as an antifungal agent in seed grain fed to animals. It is also found in older antiseptics and in some medical preservatives, including trace amounts of thimerosal in some childhood vaccines.

Causes and symptoms

• inhalation of vapors from spills, breakage of mercury-containing devices, off-gassing from polyurethane flooring containing a mercury catalyst, or mercury accumulation in poorly ventilated buildings
• breathing contaminated air from incinerators or industry
• inadequate remediation of toxic sites
• mercury used in cultural rituals or ceremonies
• mercury tracked home from workplaces
• mercury-based amalgams in dental fillings
• swallowing or inhaling mercury-containing batteries or their components
• direct skin contact with the element or its compounds

• form of mercury
• dose
• route of exposure—inhaled, ingested, or skin contact
• child's age, with fetuses and very young children being most susceptible
• child's health

• a metallic taste
• swollen, bleeding gums
• skin rashes
• eye irritation
• respiratory symptoms, especially in children, including severe coughing, shortness of breath, or difficulty breathing
• gastrointestinal symptoms, including nausea, vomiting, and diarrhea
• fever and chills
• high blood pressure or heart rate
• headaches
• neuromuscular symptoms, such as weakness, twitching, tremors, muscle atrophy, and impaired nerve responses
• emotional effects, such as mood swings, irritability, nervousness, or excessive shyness
• insomnia
• disturbed sensations
• cognitive impairment
• with high exposure, kidney impairment, respiratory failure, and death

• skin rashes and dermatitis
• metallic taste
• drooling
• mouth lesions, severe mouth pain, and throat swelling
• severe abdominal pain
• vomiting
• bloody diarrhea
• decreased or absent urination
• severe breathing difficulty
• muscle weakness
• mood swings
• memory loss
• mental disturbances
• shock
• kidney failure
• death

• “pins and needles” in the hands and feet and around the mouth
• numbness or pain on the skin
• poor coordination
• tremors
• muscle weakness
• impaired vision or blindness
• impaired speech and hearing
• impaired memory
• seizures and death with high-level exposure

Diagnosis

• the type and amount of exposure
• the time and duration of exposure
• the name of the product and its ingredients and strength

• For swallowed inorganic mercury, an endoscope—a flexible instrument with a camera—may be inserted through the throat to look for burns in the esophagus or stomach.
• X-rays are taken immediately to locate swallowed batteries and monitor their passing through the gastrointestinal tract.
• X-rays may be taken to diagnose lung or kidney damage.

Treatment

• humidified oxygen or air
• a breathing tube inserted in the lungs
• suctioning mercury out of the lungs

• Swallowed mercuric oxide may be treated by gastric lavage, in which a tube is inserted through the mouth to wash out the stomach.
• Swallowed mercuric chloride may be treated by making the child vomit.
• Endoscopy may be used to remove a swallowed battery from the esophagus or stomach.
• An inhaled battery is removed immediately from the larynx with a laryngoscope or from the lungs with a bronchoscope or by surgery.

• activated charcoal to absorb swallowed mercury in the stomach
• drugs to induce vomiting for mercuric chloride poisoning
• laxatives for mercuric oxide or mercuric chloride poisoning
• medications to treat symptoms

Prognosis

• A single low-level exposure to elemental mercury does not usually require treatment and is unlikely to have long-term effects.
• Untreated mercury poisoning can eventually cause pain, muscle weakness, vision loss, paralysis, or death.
• Severe elemental mercury poisoning can cause long-term damage to the lungs, kidneys, and central nervous system, including brain damage. Very large exposures are usually fatal.
• Swallowed batteries usually pass through the gastrointestinal tract without causing serious damage; however, the prognosis depends on the type of battery and how quickly the condition is treated.
• Severe inorganic mercury poisoning can cause massive blood and fluid loss, kidney failure, and probable death.
• Mercuric chloride is very toxic and even small swallowed doses can cause kidney failure and death. The prognosis depends on the amount of mercury, the symptoms within the first 10–15 minutes, and how quickly the poisoning is treated. Poisoning that occurs slowly over time may result in permanent brain damage.
• Mercuric oxide poisoning also can lead to organ failure and death.
• Damage from methylmercury is irreversible, although the symptoms do not usually worsen without additional exposure. Chronic brain damage from organic mercury poisoning is hard to treat and some children never recover. Methylmercury poisoning may also increase the risk for heart attacks.
• Both mercuric chloride and methylmercury are considered possible carcinogens.

Prevention

• not eat swordfish, shark, king mackerel, or tilefish, all of which have high mercury levels
• eat up to 12 ounces (340 g or two average portions) per week of a variety of low-mercury fish and shellfish, such as shrimp, canned light tuna, salmon, pollock, catfish, fish sticks, or fast-food fish
• eat no more than six ounces (170 grams) per week of albacore (“white”) tuna steak, which has higher levels of mercury
• check local advisories for fish caught by family and friends in local waters
• eat no more than six ounces (170 grams) per week of noncommercially caught fish from local waters if no advisories are available, and eat no other fish during the week
• feed young children smaller portions of fish