Strong contamination with ethidium bromide - (Jun/04/2007 )
hallo undergrad67,
don´t be too scared. In my early days in the lab i also accidentaly immersioned my whole ellbow in electrophoresis buffer containing EtdBr. I think, in far future we all will suffer from something strange. There could be many chemicals with cumulative dangerous effects (not known until now). But I try to work as safe as possible to not endanger me or some of my colleagues.
Thank you!
It'll very helpfull for my manual!
The mutagen data comes from bacteria (Ames test), I don't think it's ever been shown to have a carcinogenic effect in animals. I'm with Perneseblue, I really don't think it's that bad... I'm more concerned for T. Reesei! Injected with a needle! 
Ethidium is certainly mutagenic, and my well also be carcinogenic. However, it does not enter live cells with any efficiency. Also, the cells on the surface of your hand are dead and form a protective barrier. Even if you exposed live cells in your hand (i.e. through a would) the ethidium would not get into the live cells effectively. The mutagenesis data that most people refer to was done using the Ames test with bacteria. I would not worry.
Having said that, though, it is always better to be safe than sorry. I'm not saying you should not wear gloves or not take adequate protection against ethidium and most other chemicals in the lab.
I just spoke with the guy which have wrote the french safety data about etbr. He told me that etbr is much more reactif than what we expected and consequently by ingestion or contact (he was less sure about inhalation) it arise in the cell in a less dangerous form. He was very sure of him when he told me that the quantity that I ingested could not lead to a cancer. Hope he is true, but it one of the most inform researcher about this chemistry.
As you know ethidium (aka homidium) is also used as trypanocide in cattle, sheep, goat ect... No ADI (admitted daily intake) are available for ethidium however there is one for isometamidium which is a closely related to homidium. Also it was found that isometamidium is transform in homidium in the body (less thant 1%)(http://www.inchem.org/documents/jecfa/jecmono/v31je10.htm).
The ADI of isometamidium is 0-100 microgramme/kg (http://66.102.9.104/search?q=cache:7ct_Z9QkXWwJ:www.ipfsaph.org/cds_static/en/jecfa_veterinary_drug_residue_isometamidium_en_cthttpwwwfaoorgaosipfsaphinformat
ionsourcejecfa_JECFAEVAL57.html+isometamidium+who+adi&hl=en&ct=clnk&cd=1&gl=uk).
isometamidium based on the non-toxic dose level of 50 mg/kg bw/day
in the 13-week rat study and a safety factor of 500. The Committee
chose this safety factor because of the marginal pharmacological
effects seen at the lowest dose in the rat study and the limited
extent of the data available, although it recognized that neither
the drug nor its metabolites were bioavailable when given by the
oral route.
So if isomethidium give rise to 0.1% of homidium, the proportionnal ADI of homidium could be : 0.1 microgramme par kg so 6 microgramme for a 60 kg person.
In this study, it is shown that isometamidium have a strongest toxic effect than homidium: http://www.inchem.org/documents/jecfa/jecmono/v25je10.htm
I usually wouldnt be skeptical if I got a drop of EtBr contaminated buffer on me.
My reasoning. First, it is already been diluted. Second EtBr is sensitive towards light and easily degraded once it is exposed to light.
I didnt know ethidium is also known as homidium. I guess homidium is just some commercial name for ethidium. Thanks for the info though. 
Drink coffee if you ingested Etbr?
De-intercalation of ethidium bromide and acridine orange by xanthine derivatives and their modulatory effect on anticancer agents: a study of DNA-directed toxicity enlightened by time correlated single photon counting:
http://www.ncbi.nlm.nih.gov/sites/entrez?c...p;dopt=Citation