Standard operating procedures 8/2009
Judelson lab SOP: Working with Ethidium Bromide
Ethidium bromide (EtBr) is routinely used in gel electrophoresis for visualizing nucleic acids.
You should be aware of the risks of handing EtBr, and of procedures to reduce risk.
The hazards
As overexposure to EtBr usually does not result in immediate symptoms, a false sense of
security can result. However, it is also a potent mutagen, a suspected carcinogen, and is
moderately toxic. EtBr may be absorbed through the skin.
Personal protective equipment (PPE)
Wear gloves whenever handling bottles or solutions containing EtBr. If handling dry EtBr (as a
powder, for example), also wear a mask and lab coat.
Weighing out dry EtBr
This is extremely hazardous, and must be done in a chemical hood.
Pipetting EtBr solutions when making gels
The EtBr stock bottle is kept in a special tray, which also contains a pipettor dedicated to
aliquoting small amounts of EtBr. To prevent the spread of EtBr spills:
1. All pipetting of EtBr should be done in or over the tray.
2. Do not move the pipette tip beyond the tray area, to ensure that any drips will be contained.
3. Do not put the stock bottle on the counter top; keep it in the tray.
4. Be careful when handling the stock bottle. Don't tip it to the side, to help keep all of the EtBr
at the bottom of the bottle and not on the lid.
5. Dispose of the used pipette tip in the waste container.
6. After pipetting, check to make sure that the stock bottle, the pipettor, the countertop, and your
fingers are not contaminated. If anything is red, that means you have contamination!
7. Clean up spills as directed below.
Decontaminating EtBr spills on surfaces
1. Absorb liquid with dry paper towels and place into the large EtBr waste container.
2. Wash area with soapy water.
3. Rinse five times with wet paper towels, using a fresh towel each time.
4. Use a handheld UV lamp to check on the completeness of the cleanup.
(alternative decontamination solution, for large spills: 4.2 grams of sodium nitrite and 20 ml of
50% hypophosphorous acid in 300 ml of water, freshly made).
Decontaminating EtBr spills on skin
Rinse affected skin with water, then wash gently with soap, then rinse for 15 minutes.
Disposing of gels containing EtBr
1. Open the white container used for gel waste using the foot pedal.
2. Insert your gel.
3. When the container is full, notify Howard Judelson.
Disposing of gel staining solutions containing EtBr
1. Open the white container used for liquid waste using the foot pedal.
2. After checking to ensure that the container is not full, carefully pour in your solution.
(the container contains an absorbent for the EtBr; when the container is full, after letting it sit for
12 hr, the liquid can be poured down the sink. Keep the absorbent in the container.)