7.19.1 Dry Ethidium Bromide Wastes, Including Gloves and Papers

• All materials contaminated with ethidium bromide (EtBr)—including wipes, paper towels, gloves, and bench pads—must be managed as hazardous chemical waste, regardless of whether they fluoresce under UV light.
• Submit through askEHS for Chemical Waste Collection. Clearly identify the contents as “Ethidium Bromide Contaminated Waste.”

Ethidium Bromide Gels

• EtBr-containing gels (agarose or polyacrylamide) must be collected in a sealed container or bag and labeled as hazardous waste.
• Do not place gels in the regular trash, even if they do not fluoresce under UV light. New York State DEC hazardous waste regulations require that all mutagenic dye waste be handled through EHS.
• Submit via askEHS using the blue Contaminated Waste Label.

Liquids (Aqueous, Non-Flammable)

• Aqueous EtBr solutions must not be poured down the drain. Drain disposal is prohibited under NYSDEC regulations unless explicitly authorized by Cornell EHS.
• Dilute solutions can be treated with activated carbon adsorption (e.g., carbon “tea bags” or BondEX Detoxification Cartridges). The treated filtrate may only be drain-disposed if no fluorescence is observed under UV light.
• All used carbon filters, tea bags, or cartridges must be collected and submitted as hazardous waste through askEHS with a Contaminated Waste Label.

Liquids (Containing Flammable Solvents)

• Any EtBr waste mixed with flammable solvents (e.g., butanol, ethanol, isopropanol) is considered hazardous waste and must be submitted to EHS for pickup. Drain disposal is prohibited.

Concentrated Mutagenic Dyes

• Concentrated EtBr powders, stock solutions, and any unusable dye preparations are regulated as hazardous chemical waste in New York State.
• Dyes absorbed onto filter media for concentration or cleanup must also be submitted through askEHS as hazardous waste with the Contaminated Waste Label.

7.19.2 Deactivation Procedures

Safe management of ethidium bromide (EtBr) involves both prevention of exposure and proper handling of waste. Because EtBr is a potent mutagen, waste solutions, gels, and contaminated surfaces must be treated as hazardous chemical waste. Modern best practice focuses on adsorption and controlled collection rather than bleach oxidation, which is no longer recommended due to incomplete destruction and formation of chlorinated byproducts.

Activated Charcoal Adsorption

Aqueous EtBr solutions can be treated using activated charcoal filters, columns, or commercial "tea bag" kits. These methods remove EtBr by adsorption. After treatment, the filtrate may be checked under UV light to confirm the absence of orange fluorescence. If no fluorescence is observed, and if permitted by institutional policy, the filtrate may be disposed of via the sanitary drain. The spent charcoal, filters, or bags must be collected and disposed of as hazardous waste.

Resin-Based Removal

For dilute EtBr solutions (≤100 µg/mL), Amberlite XAD-16 resin or equivalent adsorption media can be used. The resin captures EtBr and is then disposed of as hazardous chemical waste. This method is sometimes used with filtration cartridges designed for nucleic acid dyes.

Surface Decontamination

For benchtops or equipment contaminated with EtBr, the preferred method is detergent cleaning and waste capture. Wipe the area thoroughly with a laboratory detergent solution (e.g., Alconox) or activated-charcoal wipes. After cleaning, inspect the surface with a handheld UV lamp (302–312 nm) to confirm no orange fluorescence remains.

All wipes, paper towels, gloves, and other cleaning materials used during decontamination must be collected in a labeled container and disposed of as hazardous waste.

Gels and Solid Waste

EtBr-containing gels (agarose or polyacrylamide) and contaminated solids must be collected as solid hazardous waste. Do not attempt to neutralize gels with bleach or dispose of them in the regular trash.

Liquids from Cleaning

Any rinse water or liquid generated during surface cleaning should be collected in a sealed, labeled container (e.g., “Aqueous Ethidium Bromide Waste”) and submitted our hazardous waste program. Even if fluorescence is absent, these liquids should not be poured down the drain without explicit approval from EHS.

Preferred Alternatives

Where possible, substitute EtBr with less hazardous nucleic acid stains such as SYBR Safe, GelRed, or GelGreen. These dyes have significantly lower mutagenic potential and can reduce the regulatory burden of disposal.