Introduction
Ethidium bromide is a nucleic acid stain. It fluoresces under ultraviolet light, especially when bound to double-stranded DNA.
Ethidium bromide is a strong mutagen and a possible carcinogen, so must be handled and disposed of correctly.
EH&S has a program to help you treat your ethidium bromide solutions with activated carbon filters, which strongly adsorb ethidium bromide. There are also chemical treatments, but filtering is easier and safer. The remaining solution is safe enough to be poured into the sanitary sewer.
Any ethidium bromide solutions if concentrations greater than 10 ug/ml (>10 ppm) must be filtered or collected as hazardous waste. EH&S strongly recommends that ethidium bromide waste at lower concentrations be filtered as well to protect the Puget Sound.
Please let us know that you are doing ethidium bromide filtration by calling us at 206.685.3759 or emailing us at chmwaste@u.washington.edu; by law we are required to keep track of all hazardous waste treatment on campus.
Disposal of dilute solutions of ethidium bromide
Ethidium bromide is available as a powder, a concentrated solution (10 mg/ml), and as a dilute solution.
EH&S recommends "GreenBags" for treating dilute solutions of ethidium bromide. We will give five free tea bags to each new laboratory. Call 206.685.3759 or email chmwaste@u.washington.edu to request them.
Disposal of concentrated solutions of ethidium bromide and powders
Concentrated solutions (10 mg/ml) of ethidium bromide must be handled as hazardous chemical waste. They will quickly saturate the activated carbon filters described above, which are designed for working or dilute solutions.
Ethidium bromide contaminated items
Items contaminated with concentrated ethidium bromide should be managed as hazardous waste.
Items contaminated with dilute ethidium bromide may be double-bagged, labeled "non-hazardous", and placed in the trash. Please double-bag to exposure to ethidium bromide of waste handlers.
Pipet tips contaminated with dilute ethidium bromide should be dried and placed into a lab glass bin.
Gels that contain ethidium bromide may be doubled-bagged, labeled "non-hazardous" and placed in the trash if they contain less than 0.1% ethidium bromide. If the gel is pink or red, the ethidium concentration is higher than 0.1%. In this case, the gel should be handled as hazardous waste.
Ethidium bromide spills
Wear protective clothing. Clean spills of ethidium bromide carefully with soap and water. Collect the soap, water and ethidium bromide mixture onto absorbent material. If concentrated or powdered ethidium bromide was spilled, place it in a sturdy screwtop container and dispose of as hazardous waste. All other materials may go in the trash after you double bag it and label it "non-hazardous".
Other dyes
Other nucleic acid dyes and stains, such as SYBR Green, are also mutagens and possible carcinogens. They should be treated like ethidium bromide with the methods above.
Less toxic alternatives to ethidium bromide
Less mutagenic alternatives to ethidium bromide are available. One alternative is SYBER-Safe. It works as well as ethidium bromide in many situations. However, although it is less mutagenic than ethidium bromide, it still is mutagenic enough that UW EH&S recommends (as do other universities) that it be handled and treated like ethidium bromide. However, EH&S still encourages you to consider this or other alternatives that might reduce the risk to your health while you are using them.
Other recommendations
To minimize your exposure to ethidium bromide, EH&S recommends that you purchase pre-mixed dilute solutions of ethidium bromide. You avoid exposure to concentrated ethidium bromide during mixing. Powdered ethidium bromide can be difficult to clean up safely if spilled. And, concentrated forms of ethidium bromide may NOT be filtered with the methods above. It will quickly saturate the filter and render it useless.
|
