ethidium bromide contact - (Aug/19/2016 )

Hello, I was attending a high school course at a university a couple of days ago where we were doing lab work and running a couple electrophoresis. We had just got back from lunch and I absently minded grabbed one of the gel out of the solution for a second without gloves. I immediately washed my hands with soap and talked to my lab instructor who said one time contact is alright. However I looked up ethidium bromide and it seems really scary and I was wondering if I should see a doctor or do anything. Thanks for the help!

You will be fine. Yes, the MSDS and mis-information spread around the internet is scary, but there is some reason for this. EtBr binds to DNA (technically it is called intercalates, as it fits into the minor groove on the double helix) and as a result of this binding could potentially cause either DNA damage (maybe by preventing melting of the DNA during replication) or mutation. There is some evidence that it is both mutagenic and teratogenic, but the evidence is limited and confined to the usual Ames test and the like, which are performed on bacteria. 

It should be noted that EtBr has been used extensively in labs for well over 40 years now, with no reported cases of associated cancer or sickness. It is also used as a prophylactic against sleeping sickness (in cattle admittedly), in parts of Africa at a rate of about 1 mg per kg of animal mass, with no evidence (that I can find) of reports of cancers or damage to the cattle, including calves born of the cattle being dosed with the EtBr.

Your skin is mostly waterproof and has a number of layers of dead skin cells above the actively dividing cells in the basement layer. The dead cells would be more likely to absorb any dose of EtBr that you came into contact with. Also note that the concentrations used in electrophoresis are usually in the microgram/litre range.