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Q's and A's

Questions and Answers:

These Q's and A's apply only to NIH facilities unless otherwise indicated.

Thermometers or Sphygmomanometers Mercury Waste and Disposal Mercury Contamination
  • I suspect there might have been a past spill of mercury from a broken thermometer in my lab. I don't see any mercury in the area. What should I do?
  • How can I recognize items that might contain mercury or other hazardous materials in lab facilities that are undergoing renovation or demolition?
  • What about mercury in plumbing systems? How does it get there and are there recommended procedures for removing it?
  • Where can I find information on mercury contamination levels in commercial products? I don't want to buy those that might be a problem.
Mercury Sources

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I broke a mercury thermometer. What should I do?
DO NOT ATTEMPT TO CLEAN UP MERCURY SPILLS REGARDLESS OF THEIR SIZE. Elemental mercury (metallic) has a significant vapor pressure and can therefore easily vaporize and become a potentially serious inhalation hazard. It can also be absorbed through intact skin. When a glass mercury thermometer breaks and the droplets are not cleaned up quickly, personnel working in the area can be exposed to the vapor from the metallic mercury.
  • Prevent the spread of mercury. The droplets can roll around and adhere to the sides of the laboratory casework. The area should be secured and normal activities stopped until the area has been decontaminated. This will keep the mercury from being tracked around.
  • Do not move any of the broken pieces of the thermometer. The hazardous material (HAZMAT) emergency responder who responds to the spill will use the location of the broken glass to determine the extent of the mercury spill.
  • Immediately notify the hazardous material (HAZMAT) emergency responder for your facility. On the main NIH Campus in Bethesda, call the NIH Fire Department (dial 911), on other facilities in Maryland dial 9-911. At the NIEHS campus at Research Triangle Park, call the Health and Safety Branch at 1-5010. After hours, please notify Security at 1-2800.
  • Give the responder the location of the mercury spill, your name and telephone number. HAZMAT emergency responders have the cleanup material and personal protective equipment that are specifically suited for cleaning up the mercury. Additionally, they have an analytical instrument that can detect minute quantities of mercury vapor and determine the effectiveness of the cleanup.

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Why do we have to keep mercury wastes separate from all other chemical wastes?
With appropriate precautions, pure mercury is easy and economical to recycle. On the other hand, solid and liquid wastes contaminated with mercury are difficult to treat and very expensive to dispose of. The presence of even trace amounts of mercury - as little as 0.2 milligrams per kilogram (parts per million) requires the entire quantity of waste to have to be managed as hazardous waste. Technology to completely separate mercury from certain common types of waste such as organic solvents is not available.

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What happens to mercury waste after you pick it up?
Liquid mercury collected from thermometers, sphygmomanometers and laboratory uses is shipped to off-site recycling facilities for distillation and reuse. Mercury-contaminated debris is shipped to commercial treatment and disposal facilities. They separate the mercury from the waste for reuse, or dispose of the waste in specially designed/operated incinerators. All facilities used by the NIH are permitted and inspected by the EPA and/or State pollution control agencies. 

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Where can I find replacements for mercury thermometers?
Alternative, non-mercury thermometers are found in the NIH Supply Catalog.


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Are there accuracy standards for non-mercury thermometers?
Yes. Mercury thermometers and alternative non-mercury liquid-in-glass thermometers used in laboratories should be calibrated using an approved method such those issued by the American Society for Testing and Materials (ASTM) or the International Standards Organization (ISO), and traceable to the National Institute of Standards and Technology (NIST) or other recognized standard setting organization. The reference cited below provides guidance on how to choose, use, calibrate and maintain calibration and traceability records for both glass standard thermometers and working liquid-in-glass thermometers and a listing of applicable ASTM, ISO and NIST publications.
Emory DN. Liquid-in-glass thermometers in the ISO-certified laboratory. American Laboratory News Edition 30(25):9-14 (1998).
Information on thermometers for clinical applications is available in this NIST publication:
Mangum BW, Wise JA. Standard Reference Materials: Description and use of a precision thermometer for the clinical laboratory. SRM934, NIST Special Publication 260-113, Washington DC: National Institute of Standards and Technology.  
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I suspect there might have been a past spill of mercury from a broken thermometer in my lab. I don't see any mercury in the area. What should I do?
Call the Occupational Safety and Health Branch (301) 496-1646 to have your lab checked for mercury vapors. When mercury is spilled it usually splatters into small droplets, many too small to see. These can cling to objects - even vertical surfaces. Liquid mercury often collects in cracks, crevices and other areas that are hard to observe. Even small amounts of mercury can contaminate indoor air to unsafe levels.


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I have mercury thermometers in my lab. How should I dispose of them?
Place them in a break resistant, leak proof container such as a plastic bottle. Fill out and attach a NIH Chemical Waste tag and call the NIH Chemical Waste Disposal Service at 301-496-4710 for pick-up and recycling. Please do not package mercury wastes in water; this increases the total quantity of material that must be treated as hazardous waste.


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I have mercury-containing equipment that I will be turning in as surplus property. What should I do about the mercury?
Do not move the equipment or attempt to remove the mercury yourself. Call the NIH Chemical Waste Disposal Service (CWDS) at 301-497-4710 for assistance. A chemist will remove the mercury and recycle it. After the equipment has been drained, complete and attach a Certification that the Property is Free from Hazards tag (NIH Form 2683) . On the line for chemical hazards, indicate that the item previously contained mercury. Then dispose of the item in accordance with NIH procedures for surplus property. NIH Policy Manual. 26101-25-2 - PERSONAL PROPERTY MANAGEMENT GUIDE


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I have some mercury containing items at home to dispose of. What should I do with them?
These should be disposed of as hazardous wastes - never in the trash or down the drain. Most counties operate "amnesty days" or other programs for disposal of hazardous wastes generated by households. Contact your county health department or environmental agency for assistance. Until you are able to dispose of the waste make sure it is in a leak-proof and break-resistant container. Label it "Mercury Waste-Toxic" and keep it away from children and pets.


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Where can I get more information on the pros and cons of mercury thermometers and blood pressure monitoring equipment in clinical applications?
A list of articles on the subject is provided in the Hatter's Library section of this site.

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The literature indicates that mercury thermometers or sphygmomanometers are the most accurate/reliable method in my clinical/research application. Do I have to switch to non-mercury units?

No. This is a voluntary program. If the needs of patient diagnosis, treatment or research are better served, continue to use the mercury-based unit with appropriate precautions. We recommend that you check with the safety specialist of your IC. Some ICs may have policies requiring use of non-mercury units or administrative approval to procure or continue use of mercury devices.

In most cases the health, safety and environmental hazards outweigh the potential benefits of continuing use of mercury devices. Generally, non-mercury units provide satisfactory results if the equipment is appropriate for the application, calibrated properly, and the users have been trained on its use. Major healthcare and research facilities are now mercury free. Legislative actions are pending in some areas that may ban mercury thermometers.

If you must continue using mercury thermometers, consider using Teflon coated or armored thermometers. These resist breakage and contain the mercury if they are broken.


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Where can I find information on mercury contamination levels in commercial products? I don't want to buy those that might be a problem.
The Mercury Work Group of Medical Academic and Scientific Community Organization, Inc (MASCO) has developed the Mercury Products Database, a relational database containing information on the mercury content of hundreds of products used in various facilities, including clinical and research laboratories. It can be accessed at the website below and allows for both the review and input of information. You can use this document to get critical mercury content information on products by name or type of use and find out if there are known mercury-free alternatives. External Site


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What about mercury in lighting systems? Can it be eliminated?

Many types of light bulbs contain mercury. Common examples include fluorescent light tubes, germicidal (UV) lights, and high-pressure sodium vapor lights. Generally, manufacturers are attempting to lower the amounts of mercury and lead used in lighting. For some types of bulbs, mercury has been totally eliminated. Mercury-free fluorescent lighting is not yet available; however, light tubes are now manufactured with levels of mercury low enough to pass EPA's Toxicity Characteristic Leaching Procedure (TCLP) test and do not have to be managed as hazardous waste. A composite sample of used fluorescent light tubes collected on the NIH Bethesda campus passed the TCLP test.

Some uses of mercury vapor lamps are essential in health care facilities and plans for eliminating mercury do not include phasing out fluorescent lamps. It's often more energy efficient to use such lamps, and from a total life cycle perspective, the use of energy efficient mercury lamps actually reduces mercury pollution. By requiring less energy to run, there will be less mercury released into the atmosphere from coal used to power generators to produce electricity.

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How can I recognize items that might contain mercury or other hazardous materials in lab facilities that are undergoing renovation or demolition?
The Florida Center for Solid and Hazardous Waste Management and the Florida Department of Environmental Protection have teamed to develop a website titled Recommended Management Practices for Removing Hazardous Building Components Prior to Demolition. It contains several fact sheets designed for contractors, facility operators, building officials and clients; a detailed guidebook; and a virtual tour of common hazardous building components encountered in demolition projects. All of the guidance documents include photographs of items that may contain hazardous materials assist in their recognition. External Site

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What about mercury in plumbing systems? How does it get there and are there recommended procedures for removing it?

Because mercury metal is insoluble and much heavier than water, it may collect in traps and reside there for very long periods without being flushed out. If you suspect that metallic mercury has been discharged or spilled in sinks, you should report this to your facility's HAZMAT emergency responder. The traps and their contents may need to be removed and disposed as hazardous waste. The use of "mercury sniffers" (air analysis instrumentation) to check drains for such contamination may not be effective since mercury vapors may not be present in detectable concentrations in the air when the metal is submerged under water in the trap.

The more common source of mercury in plumbing systems is from biological processes that slowly concentrate trace levels of mercury that are often present in the wastewater.



This page was last updated on Jul 12, 2018