Hazard Alert - Ethidium Bromide Disposal

Ethidium Bromide is classed as a mutagen and possible carcinogen and teratogen. Ethidium Bromide must not be disposed of without deactivation. Following a recent explosion due to unsafe handling of Ethidium Bromide during deactivation for disposal, this Hazard Alert is supplied for your awareness and safety.

The explosion occurred, even though the correct 'recipe' for deactivation was being used, due to the following:

• The deactivation was carried out in a winchester containing acid residue, which reacted with the bleach to form chlorine gas.
• The winchester was then sealed causing a build up of chlorine gas to an explosive pressure.

Safe Deactivation Methods

Ethidium Bromide is normally used in small quantities and can be converted to the physically inactive product 2-carboxybenzophenone with chlorine bleach. The product solution (see deactivation method below) does not show excess mutagenicity over standards in the Ames test (Armour Et al, University & Colleges Hazardous Waste Conference, 1992, Columbia, Missouri).

• Accumulated liquid waste should be stored safely before deactivation
• Store in a large pre-cleaned winchester /flask
• Store in an uncluttered fume cupboard
• Label the flask appropriately.

Deactivation (liquid waste)

• Wear protective gloves, lab coat and goggles
• Work in a fume hood
• Use a 5 litre beaker on a magnetic stirrer
• To a solution of 34mg of Ethidium Bromide in 100ml water, add 300ml of household chlorine bleach and stir overnight at room temperature.
• Flush down the sink with copious water

Gels should be incinerated with biohazard waste
Solid waste should be dissolved in water in a fume cupboard before deactivation as liquid waste following the method above.

Handling of chemicals must be carried out with great care and according to the UWA policy for Handling and Storage of Chemicals. Obtain and read the manufacturer's material safety data sheet (MSDS) for every chemical used

• Find out beforehand the correct treatment, in the case of an accident, for the harmful effects of hazardous materials
• Use the minimum amount of any chemical and if there is a choice, use the least toxic or least flammable substances [consider 4',6-diamidino-2-phenylindole dihydrochloride:hydrate (DAPI)]
• Use correct handling methods, protective devices and clothing required for the particular substance (gloves, lab coat, eye protection)
• Clearly label all containers and include a 'mutagen' warning label. Always carry out correct storage and disposal procedures
• Lock scheduled drugs and poisons in a cupboard
• Wash hands after handling chemicals.