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Handling of ethidium bromide - Regarding material that is constantly used for EtBr (Mar/27/2008 )


In the only lab I've worked before they had a special area for EtBr stuff (Electrophoresis apparatus, flasks for agarose gel preparation, micropipettes, etc) that was in constant contact with EtBr and was not used for anything else, they wouldn't touch any of that with bare hands.

In the lab I'm working now they seem to be more relaxed about it. They do have a special bin to dispose agarose gels but that's about it. They wash the electrophoresis equipment and then it seems to be ok for them to handle it with bare hands.

So I'm confused, am I paranoid about EtBR? Is it really ok to touch the equipment once it has been washed (rinsed with tap water)?



Below are the instructions that I found on a University's intranet.
My personal opinion is: never handle EtBr with bare hands or without labcoat, avoid using it in the form of powder, don't pour used running buffer down the sink, and contaminate as fewer labware (flasks etc) as possible. EtBr is not a proven carcinogen, but it is a strong mutagen. And, as far as my experience goes, new studies have always proven that nasty chemicals are even nastier than we first thought, rather than the other way round. So, better safe than sorry!

Ethidium Bromide Use and Disposal (EtBr; 2,7-diamino-10-ethyl-phenylphenanthridium bromide)

Risk Phrases 23, 40 Safety Phrases 24/25, 26, 28
Widely used for the visualization of nucleic acids in electrophoretic gels. Though not a carcinogen, it behaves as a mutagen in the Ames Salmonella bioassay.
It is strongly recommended that EtBr is purchased as a ready prepared aqueous solution to avoid weighing solids. Solutions are available from Fisher, VWR
(Merck) and Sigma, 10ml volumes are recommended.
Always wear suitable protective clothing (lab coat), chemical resistant gloves, face/eye protection when handling Ethidium Bromide solutions, gels, or waste.
Alternative Methods for the use of Ethidium Bromide
Ethidium Bromide is incorporated evenly throughout the gel. Ethidium Bromide should only be added to molten agarose solutions when the latter has cooled to
below 50 0C. This prevents the possible release of Ethidium Bromide in the vapour. This method effectively traps the compound within the gel although under
running conditions some Ethidium Bromide will leach from the gel into the buffer, but with this method over 90% of the Ethidium Bromide will be disposed of as
solid waste with the gels.
Staining the DNA after the gel has been run. If this is the protocol adopted the running buffer solution is not contaminated with Ethidium Bromide so may be
discharged to drains without treatment. The gel is stained in a dish containing a small volume of Ethidium Bromide solution. The solution may be re-used so the
volume of aqueous waste contaminated with Ethidium Bromide is much lower.
In the School of Biological Sciences the first method is the recommended protocol.
All gels must be transported in a robust leak-proof container and the following precautions taken to avoid contamination of non-laboratory areas and door handles.
Staff carrying gels must keep one hand un-gloved, to open doors without contamination. The other hand should be gloved to carry the container with the gel.
A second clean glove should be taken for handling the gel in a room suitable for viewing gels. The room must have adequate ventilation for working with ultraviolet
radiation and appropriate safety visor (see separate procedure).
The second glove must be removed before handling items to be touched by those not wearing gloves (e.g. door handles, light switches and computer keyboards).
Disposal of Ethidium bromide
Anglian Water's Trade Effluent Consents prohibit the disposal to drain of virtually any toxic or mutagenic substance under blanket restrictions covering the risk to
effective sewage treatment & health of sewerage workers. If in doubt, seek advice before washing ANY waste chemical down the drain. Small bottles of stock
solutions can be sent for disposal as special waste
Aqueous solutions of Ethidium bromide (>1.0μg/ml) may be disposed of in one of two ways:
The Ethidium bromide can be adsorbed onto an ion exchange column specifically for this purpose, available from Merck (catalogue number 437212Y). These
columns will adsorb at least 300mg of Ethidium bromide; the waste liquid may then be discarded to drain. The resultant bound material should be packaged up &
labelled for collection as special waste. You will need to make an estimate on the label of the quantity of EtBr. Such treatment is the responsibility of the user
under CoSHH and must form part of your risk assessment.
The Ethidium bromide may be adsorbed onto activated charcoal at a rate of 100mg charcoal to 50mg Ethidium bromide. This mixture should be left overnight
before filtering off the solid, which should, then be disposed of as for special waste (see above). The waste liquid can be discarded to drain
All gels containing Ethidium bromide should be dried down in plastic bags inside leak proof trays, all of which must be in a fume cupboard. The dried gels can then
be packaged labelled and disposed of as special waste.


I know that some people think that EtBr is not dangerous at all (I heard a tale about one of our Prof even drinking it by accident...but I donot know if this is a LabMyth)...But I would agree with f2dU! Be as careful as you can when handling chemicals with warnings on them....not only but esp. EtBr!

In every lab there is somebody who seems not to like his/her health (and is a danger to the health of all the others angry.gif ohmy.gif sad.gif ), as they use to play around with hazardous material and toxic chemicals: one of our students who was complaining about the bad smell in the lab...she was working with a buffer containing mercaptoethanol.....whe she was told that she should try to work in a fume hood the smell was a miracle to her....she did not even think of ME to be toxic....didn't looked at the bottle when she made the buffer!

The following text is from the warning posted on the door of our EtBr work room:

Hazards Identification
Emergency Overview

SAF-T-DATA™ Ratings (Provided here for your convenience)
Health Rating: 4 - Extreme (Poison)
Flammability Rating: 1 - Slight
Reactivity Rating: 1 - Slight
Contact Rating: 3 - Severe (Life)
Storage Color Code: Blue (Health)

Potential Health Effects

The dust is very toxic by inhalation. Inhalation of dust irritates the respiratory tract.
No information found, but compound should be handled as a potential health hazard.
Skin Contact:
Inflammation and discoloration of the skin may occur after contact. Contact will stain the skin purple.
Eye Contact:
Causes irritation, redness, and pain.
Chronic Exposure:
May cause heritable genetic damage.
Aggravation of Pre-existing Conditions:
No information found.


Thanks for your replies, I'll keep my distance from EtBr even if they give me weird looks.


QUOTE (gebirgsziege @ Mar 27 2008, 08:12 AM)
No information found, but compound should be handled as a potential health hazard.

even though some people said it is safe to handle EtBr with bare hand as long as you don't have any cuts, opening or wound on your skin....
but you'll never know what people will find out in the future. maybe the consequences will happen after few decades...

always be careful with EtBr.

Just to be safe then sorry.