ETHIDIUM BROMIDE DISPOSAL PROCEDURES

(from EH&S memo revised Jan. 4, 2013 [pdf])

Ethidium bromide is a highly toxic chemical, and probable mutagen, frequently used to identify DNA. The following are procedures that should be followed for the proper disposal of ethidium bromide waste to protect public health and the environment.

1. Solid ethidium bromide waste (for example gels) should be collected in closed, labeled containers and turned in to EH&S for disposal by incineration via our hazardous waste contractor.
2. Liquid ethidium bromide waste with a concentration less than 1.0 μg/ml should be filtered via AMRESCO Destaining Bags (which look like standard tea bags). The destaining bags are VERY SIMPLE and CHEAP to use. Simply drop a destaining bag into your solution, periodically swirl it around a few times, and let it stand overnight. In the morning, remove the bag and collect it as solid ethidium bromide waste. Then perform a spot check of the solution using a UV transilluminator to see if it fluoresces. If it does not, approximately 99% of the ethidium bromide has been removed and the solution is now safe to pour down the drain- provided no other hazardous chemicals are present.  Attached with Jan. 4, 2013 memo (also linked above) is a one page Technical Bulletin by AMRESCO outlining the destaining bags capabilities and limitations. AMRESCO’s phone number and web address are also provided.
3. Liquid ethidium bromide waste with a concentration equal to or above 1.0 μg/ml should be collected in closed, labeled containers and turned in to Environmental Health and Safety for disposal by incineration via our hazardous waste contractor. This is due to the fact that the destaining bags have a more limited effectiveness at higher concentrations of ethidium bromide and this waste poses a larger hazard to health and the environment.
4. If it is possible to use a less hazardous chemical for the identification of DNA, please do so. Some experiments may allow the use of “Sybr Safe” or “EZ-Vision” produced by AMRESCO and other chemical supply companies. Overall, other disposal procedures for the removal/neutralization of ethidium bromide should not be performed. A common past practice of oxidizing ethidium bromide with household bleach has shown to produce compounds that are even more hazardous.
5. If you have any questions concerning this memo or waste disposal in general, please do not hesitate to contact the Environmental Health and Safety Office at 575-646-3327, e-mail: Kaczmare @ nmsu.edu, or visit our web site at https://safety.nmsu.edu.