Dealing with mercury spills

Mercury is extremely toxic. When spilled, vapor accumulates and is absorbed by inhalation, causing long-term neurological and kidney damage.
The information below was scanned by computer from an article in American Laboratory.

Here's the situation:

Thermometer breaks in glassware oven.
Oven shut off, unplugged, taped shut, and cooled.
Big plumes of Hg vapor observed leaking out of oven door cracks and thermometer hole via its absorption of UV between a TLC lamp and a fluorescent plate. (Highly instructive for persons from all walks of life, and a fun afternoon family activity)

Management and control of Hg exposure

American Laboratory July, 1988
David N Easton
[Scanned! And you know what that means!!]

Because mercury will disperse into fine droplets throughout the area where it is spilled, an effective cleanup procedure requires two steps. Always wear rubber gloves and take care to avoid spreading the spill through inadvertent contact. Wear appropriate respiratory protection if testing shows that levels of airborne mercury are high.


  1. Notify the Institute's Safety Officer or one of the secretaries.
  2. Thoroughly ventilate the area.
  3. Remove any contaminated clothing. Be sure not to step in the spill, or you will track it around.
  4. Do not allow the mercury to go down the sink drain. Once there, it has the potential to contaminate the water system
  5. If you are wearing gold jewelry, either remove the jewelry or wear good protective gloves. If the liquid mercury contacts the gold jewelry, the mercury bonds permanently to the gold and ruins it.
  6. While wearing rubber or plastic gloves, carefully pick up any broken glass and debris, Take care not to spread the mercury. Dispose of the glass in a zip-lock plastic bag or other proper disposal container.
  7. NEVER use a ShopVac or vacuum cleaner to clean up.
  8. Consolidate the spill as much as possible by using a thin piece of cardboard or plastic. Cordon off the area to avoid traffic and dispersal of the material.
  9. Build a trap consisting of a filter flask connected to a vacuum source at the side-arm and a length of Tygon tubing at the inlet. Collect all visible droplets. A Pasteur pipet at the inlet end of the tube (A) facilitates the pickup. Make sure the flask contains charcoal so mercury does not get sucked into the vacuum.
    Suction flask
  10. Alternatively, use an eyedropper or Pasteur pipet. A good flashlight is essential for finding fugitive droplets.
  11. After the gross contamination has been removed, sprinkle the entire area of the spill with a liberal application of elemental zinc powder.
  12. Dampen the zinc powder with dilute (5-10%) sulfuric acid solution to create a paste-like consistency. Work the paste into the contaminated surface with a sponge or a brush.
  13. After the paste dries to a light gray color, it may be swept up for routine disposal. The residual material is removed with soap and water.
  14. Wrap all materials, including the the sponge and brush in a plastic bag and dispose of as chemically hazardous waste.

    This procedure results in an amalgam of mercury and zinc (the acidic solution shifts the equilibrium toward the bound product). The more conventional treatment with calcium polysulfide or flowers of sulfur merely reduces the vapor pressure by coating the droplets. Subsequent frictional forces can disrupt this coating and result in additional vapor release.

    Copper, gold or almost any other metal except iron or platinum may be substituted for zinc.

When a 5-lb bottle of elemental mercury was dropped by an employee of the University of Virginia's Hospital Supply Storeroom, broken glass and larger mercury pools were hastily swept up. The Office of Environmental Health and Safety was called to pick up the waste and survey the damage.

The severity of the problem was realized as soon as the cleanup crew arrived. In just 30 min, storeroom personnel had tracked mercury throughout the area. Fugitive mercury droplets had rolled everywhere.

The storeroom was immediately shut down and the State Department of Emergency Services was called in, as a spill of this magnitude exceeded the hospital's cleanup capabilities.

The problem with any mercury spill is that mercury easily vaporizes at room temperature, where it can be breathed or absorbed through the skin. Prolonged exposure to mercury vapor adversely affects the nervous system. Symptoms may include irritability, depression, vivid dreams, inflammation of the gums, insomnia, loss of memory, and/or concentration and constricted visual fields.

The OSHA (Occupational Safety and Health Administration) permissible exposure limit (PEL) for Hg is 0. 10 mg/m 3 and the ACGIH threshold limit value (TLV) for Hg is 0.05 mg/m 3 . Both of these standards are based on an exposure for an 8-hr day.

It takes very little mercury to create an unsafe environment. Quantities as low as I mL can evaporate over a period of time and contaminate millions of cubic feet of air to levels in excess of allowable limits.

The airborne concentration of mercury vapor was measured in the storeroom, and found to be above 0.3 mg/m3. Improper spill cleanup techniques had broken the droplets into smaller particles that collected in porous surfaces and floor cracks. Mercury had been tracked all over the room on shoes and the wheels of medical carts.

The following day, the Department of Emergency Services helped clean up the remaining mercury with a special mercury vacuum cleaner. Results were tested with a direct-reading mercury analyzer. Testing showed that levels were then below 0. 1 mg/m 3 . The Department left the analyzer with the hospital for con tinued testing.

By the following morning, mercury vapor levels had dropped to 0.05--0.06 Mg/M3. Pans of the storeroom were reopened for essential supplies and orders. Unfortunately, by afternoon, the analyzer showed that mercury vapor levels were starting to rise again. 'Me area was cleaned using a paste of zinc powder, a technique that has become an integral part of the cleanup procedure (Figure 1).

By that time, 22 employees were identified as having been potentially exposed to excessive mercury levels. They received a medical evaluation consisting of medical history, physical exam, laboratory tests, and computerized neurobehavioral testing. Laboratory tests included spot urine tests, 14-hr urine follow-ups, and blood mercury determinations. All the test results were negative.

While the state's mercury detector was still on loan, some adjacent hospital areas were surveyed for excessive mercury vapor concentrations.

The first location was the medical repair room where employees of the Clinical Engineering Department repair such mercury-filled instrumentation as incubator thermometers, sphygmomanometers, and other differential pressure devices. (Wall mounted units are frequently knocked over in patient rooms when beds are adjusted; and tripod units are overturned on a regular basis. The mercury-filled tubes shatter upon the slightest impact.

Equipment in need of repair or recalibration is sent to the Medical Repair Room. Although some mercury from broken equipment can contaminate patient rooms, most of it is usually found on the repair room floor and work counters. Employees have reported that they scooped up larger mercury puddles and threw them into open trash cans and vacuumed up the rest with a regular household vacuum cleaner. They also stomped on tiny droplets until they were no longer visible. The mercury detector confirmed the suspected high levels in the repair room. Air samples in the room showed average mercury vapor levels of 0.3 mg/m 3 ; an analysis of the vacuum cleaner's interior levels pushed the instrument's gauge off scale.

Twenty-eight employees of the Clinical Engineering Department were identified as either chronically or potentially exposed to elevated mercury levels, including those who repaired manometers, those who worked in the contaminated repair room, and others who worked in adjacent offices.

After testing, none of the employees were found to exhibit signs of mercury poisoning, although four employees were considered to have elevated blood mercury levels. Four others claimed eyelid fasciculations and depression. Two admitted increased irritability and insomnia; two others excitability, forgetfulness, anorexia, and occasional nausea.

It was obvious from the testing that mercury-contaminated areas needed to be cleaned immediately and kept mercury-free. Employees obviously needed education about the dangers of mercury vapor and instruction on proper cleanup procedures.

First, steps were taken to control access to all mercury-based materials by running all mercury acquisitions through the University Office of Environmental Health and Safety. The mercury is now stored there and not in satellite facilities like the supply storeroom.

Next, a portable mercury vapor analyzer was purchased so that mercury spills could immediately be analyzed for elevated mercury vapor levels. The analyzer selected (Figure 2) provides fast, accurate, and specific mercury-only readings through the use of gold film technology. Instruments that respond to interference?s such as organic materials are confusing to read when the mercury content of cart wheels or shoes is being analyzed.

Complete mercury spill cleanup kits were assembled. A spill response procedure was published that defined everyone's responsibilities.

Most importantly, a large employee population was made aware of the potential hazards of mercury (Figure 3). Mercury Is highly toxic-however benign or fascinating it looks. The special handling of mercury necessary for mercury cleanup was stressed because of the compound's easy vaporization and fast absorption into porous surfaces and materials.

The new procedures caused the phones in the Office of Environmental Health and Safety to ring almost immediately. It became evident that mercury was being spilled round the clock.

A skeleton mercury cleanup crew was put on duty at all hours. The hospital housekeeping staff was selected as the surrogate spill-response team.

Although a few problems were encountered initially communicating safe cleanup procedures, the staff soon took great pride in their new role. Frequent training and hands-on experience is currently provided for new personnel. With this assistance, we know when, where, and by whom mercury is spilled. It has also been very effective to devote a few minutes of Right-to-Know lectures to inform all university employees about the use and abuse of mercury.

The mercury vapor analyzer is used routinely to test patient rooms, repair areas, dental clinics, and neonatal incubators, and to test deletion after mercury spills. Problems are still encountered. In the first survey of 24 incubators, one showed a low level mercury vapor contamination (0.003 Mg/M3); another significant levels (0.020 mg/m 3). Fortunately the badly contaminated unit was used exclusively as a transport unit and any particular infant's exposure was brief. The units had to be completely dismantled and decontaminated.

The procedures that were developed for mercury spill cleanup follow. If you spill mercury (any amount):

  1. While wearing rubber or plastic gloves, carefully pick up any broken glass and debris, Take care not to spread the mercury. Dispose of the glass in a zip-lock plastic bag or other proper disposal container.
  2. Consolidate the spill as much as possible by using a thin piece of cardboard or plastic. Cordon off the area to avoid traffic and dispersal of the material.
  3. Notify your supervisor and call the University Housekeeping Office. A representative will respond to pick up spill wastes for proper disposal and to clean up the rest of the spill with proper equipment. Mercury does not evaporate rapidly, so a delay of an hour or two should not result in the accumulation of hazardous concentrations; however, the spill must be cleaned up during the work shift in which it occurred unless specific notification is provided to the supervisor of the next shift.
  4. Call the Environmental Health and Safety Office as soon as the spill is cleaned up or if there is a delay of more than two hours from the time the spill was reported. During regular work hours, a representative of the Environmental Health and Safety Office will respond to monitor the area where the spill has been cleaned.

If you call to report a spill and cleanup after regular working hours, leave a message according to the recorded instructions. The recording device will list home telephone numbers of our staff members in the case of a significant emergency.

Mr. Easton is a Certified Industrial Hygienist at the University of Virginia, Environmental Health and Safety Office. Charlottesville, Virginia. This paper was excerpted from a lecture by the author at the American Industrial Hygiene Conference in Montreal, Canada, June 1987.



After a large, one-time inhalation exposure of mercury vapor, the lungs are the main target of mercury poisoning, although other symptoms develop as well. Symptoms may develop within a few hours and include chills, metallic taste, mouth sores, swollen gums, nausea, vomiting, abdominal pain, diarrhea, headache, weakness, confusion, shortness of breath, cough, chest tightness, bronchitis, pneumonia and kidney damage.


Long-term exposure (usually work-related) of inhaled vapors is generally more dangerous than a one-time short exposure. After long-term inhalation exposure, the nervous system is the main target of toxicity. Symptoms may occur within weeks but usually develop insidiously over a period of years. Neurologic symptoms include tremors, headaches, short-term memory loss, incoordination, weakness, loss of appetite, altered sense of taste and smell, numbness and tingling in the hands and feet, insomnia, and excessive sweating. Psychiatric effects are also seen after long-term exposure. Acrodynia can result from repeated exposures to mercury-containing latex paint fumes. Acrodynia is usually seen in younger children. The symptoms include chills, sweating, body rash, irritability, sleeplessness, leg cramps, swelling of the cheeks, nose, hands and feet, light-sensitivity to the eyes and peeling skin layers on the palms of the hands and soles of the feet.

Non-inhalational exposure

Elemental metallic mercury is less toxic when ingested instead of inhaled. One patient attempted suicide with metallic mercury by injecting it intravenously, and lived to illustrate the differences in toxicity among different routes of administration:

N Engl J Med. 2000 Jun 15;342(24):1791. Images in clinical medicine.
Elemental mercury embolism to the lung. Gutierrez F, Leon L. Hospital Sotero Del Rio, Santiago, Chile.

A 21-year-old dental assistant attempted suicide by injecting 10 ml (135 g) of elemental mercury (quicksilver) intravenously. She presented to the emergency room with tachypnea, a dry cough, and bloody sputum. While breathing room air, she had a partial pressure of oxygen of 86 mm Hg. A chest radiograph showed that the mercury was distributed in the lungs in a vascular pattern that was more pronounced at the bases. The patient was discharged after one week, with improvement in her pulmonary symptoms. Oral chelation therapy with dimercaprol was given for nine months, until the patient stopped the treatment; the urinary mercury level did not change during this period. At follow-up at 10 months, she was healthy, with none of the renal, gastrointestinal, or neurologic effects that can result from the oxidation of mercury in the blood and consequent exposure of these organ systems. The abnormalities on the chest radiograph were still apparent. Although these abnormalities are striking, the absence of clinical toxicity in this patient illustrates the differences in the acute and chronic effects of exposure to elemental mercury, inorganic mercury (e.g., mercuric chloride), and organic mercury (e.g., dimethylmercury). Inorganic and organic mercury are much more toxic than elemental mercury; for example, a dose of 400 mg of mercury in the form of dimethylmercury is usually lethal.

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