Faculty and Staff

How to Handle Ethidium Bromide

Last updated September 4, 2009 6:48:53 PM PDT
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Follow these guidelines to protect yourself from injury when work involves ethidium bromide.

Ethidium bromide (C21H20BrN3) is a potent mutagen used as a nucleic acid stain. It fluoresces a red-orange color under ultraviolet light and with increased fluorescence when bound to double-stranded DNA. Ethidium bromide is typically purchased in powder or solution form and is soluble in water. The crystal or powder form is odorless and appears dark red in color.

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Obtain approval before beginning work.

Ethidium bromide requires extra precautions during use and disposal because of its highly toxic and mutagenic properties.

  • Request prior approval from your principal investigator (PI) before beginning any new project involving ethidium bromide.

Evaluate the hazards before beginning work.

  • Consult safety resources available on:
  • Consider these hazards specific to ethidium bromide:
    • In powder form, ethidium bromide is an irritant to the upper respiratory tract, eyes, and skin.
    • Ethidium bromide is strongly mutagenic, causing living cell mutations. Even though there is no evidence at this time of human carcinogenicity or teratogenicity, this material should be considered a possible carcinogen or teratogen.
  • If possible, use a less dangerous product that can perform the same task.
    • New fluorescent dyes have been developed that manufacturers, such as Molecular Probes Inc. and FMC Corporation, claim are less toxic and have greater detection sensitivity than ethidium bromide.

Follow these training guidelines.

A PI or a knowledgeable designee must provide appropriate safety training.

  • Inform employees about handling ethidium bromide, its specific hazards, and health effects.
  • Explain possible routes of exposure, as appropriate:
    • Skin absorption
    • Ingestion
    • Inhalation
  • Provide personal protective equipment and engineering controls, and train employees in their proper use.
  • Post emergency procedures in the lab and make sure everyone who works with ethidium bromide is familiar with them.
  • Keep training records on file, including:
    • Outline of information covered
    • Date
    • Names
    • Employee signatures

Be prepared for accidental spills.

Ethidium bromide spills are very serious and require immediate cleanup.

  • Read How to Handle Chemical Spills in Laboratories.
  • Keep a chemical spill kit easily accessible.
  • Print and keep the Material Safety Data Sheet for ethidium bromide with your emergency supplies.
  • Know the location of safety equipment, including eyewash, shower station, first aid kit, and Emergency Guide.
  • Clean up only very small quantities of ethidium bromide, and only if you have been properly trained. If you decide to clean up a spill, use materials appropriate for ethidium bromide:
    • Wipe up solutions with chemical absorbent pads (as found in chemical spill kits). Then wash the spill area with soap and water.
    • Avoid raising dust when cleaning up solid spills by mixing the spilled material with water and then absorbing the solution.
    • Dispose of all spill containment material as hazardous chemical waste.
  • Use of hand-held ultraviolet (UV) lamps: Some facilities use a hand-held UV lamp to check for residual ethidium bromide contamination following spill cleanup. A reddish-orange fluorescence can be detected under both "long" and "short" UV wavelengths.
    • Be aware of these limitations:
      • The ability of hand-held UV lamps to detect small spills is not guaranteed.
      • Ease of detection depends upon a variety of factors including:
        • Chemical composition of the sample
        • Wavelength of the UV lamp
        • Intensity of the lamp
      • Use of a handheld UV lamp to detect traces of ethidium bromide may serve as an occasional check of laboratory practices, but it cannot substitute for good cleanliness and careful contamination control.

Follow these purchasing and storage guidelines.

  • Buy the least amount of ethidium bromide the work requires. Do not buy in large quantities to save money.
  • Label all containers with this information:
    • Name of the material
    • Concentration
    • Warnings
    • Date, when appropriate
    • Preparer's initials, when appropriate
  • Follow these storage guidelines:
    • Store unused liquid inventory in a polyethylene secondary container, large enough to capture the entire contents should the original container leak or rupture.
    • Store away from strong oxidizing agents. Contact an EH&S Research Assistance Program specialist if you have questions about chemical and container compatibility.

Control the hazards.

  • Engineering controls:
    • Minimize the possibility of inhalation by performing the following activities inside a fume hood:
      • Mixing of ethidium bromide solutions
      • Processes that may generate ethidium bromide dust or mist
  • Wear this personal protective equipment (PPE):
    • Lab coat with sleeves fully extended to the wrists
    • Safety glasses or splash goggles and face shield
    • 2 layers of Nitrile surgical gloves
    • Full-length pants
    • Closed-toe shoes
    Follow these PPE guidelines:
    • Always double-check your PPE before beginning work.
    • Never re-use disposable gloves.
    • Leave all personal protective equipment in the lab when your work is complete.
    • Caution: When an ultraviolet light source is used, follow these extra PPE requirements:
      • Avoid exposing unprotected skin and eyes to intense UV sources.
      • If the UV light is aimed upwards, wear a UV-protective face shield when standing near the source.
      • For prolonged work close to UV light boxes or other intense sources, wrap the cuffs of your lab coat sleeves loosely with masking tape to prevent gaps where your wrists could be exposed.
      • When using ultraviolet light to visualize ethidium bromide, you must wear UV-blocking eyewear or work in a UV cabinet with shielding in place.
  • Restrict access to the work area.
  • Keep container sizes and quantities in the work area as small as possible. Transport ethidium bromide in secondary containers and only in small quantities.
  • If you suspect equipment has been contaminated with ethidium bromide, contact an EH&S Research Assistance Program specialist.

Act quickly if an exposure occurs.

Give first aid treatment, then seek medical attention immediately for any and all ethidium bromide exposures. Treat any exposure seriously, no matter how slight it may seem at the moment.

  • Ingestion: Seek medical attention immediately.
  • Skin exposure: Flush exposed skin with water for at least 15 minutes while removing any contaminated clothing.
  • Eye exposure: Flush eyes with water for at least 15 minutes. Affected individuals may need help holding their eyes open under water. Seek medical attention immediately at an emergency room.
  • For all exposures:
    • Seek medical attention immediately at an emergency room.
    • Call Campus Police at (858) 534-4357 (534-HELP) and request an ambulance if transportation is necessary.
    • Call Poison Control, (800) 222-1222, if additional information is needed.

Dispose of waste properly.

Read about how to:

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For more information, contact the chemical safety officer, (858) 822-1579.

Notice: Disposal of hazardous waste using sinks, intentional evaporation, or as regular trash is against the law. Campus laboratories must abide by strict state and federal waste disposal requirements. You may be held liable for violations of applicable laws.