Ethidium bromide carcinogenicity?

Stacy Ferguson sferguso at
Tue Apr 11 19:38:31 EST 1995

In article <edbeaty-1104951801360001 at>,
Ed Beaty <edbeaty at> wrote:
>The question has come up in my lab again about the possible risk of
>exposure to Ethidium bromide.  I've heard statments to the effect that
>exposure is harmless; that it is used in Australia as a "sheep dip" to
>kill parasites but that the sheep are unharmed; that smoking is a
>hundredfold worse for you than exposure to EtBr.  What's the current
>status of this argument?  Any information would be appreciated.
>Thank you,
>Edward Beaty

Well, it's use as a sheep dip is news to me. However, I have a difficult
time believing that EtBr is harmless. Even if there were no data to indicate
that it is a mutagen, think about it. 

Here's a molecule that intercalates into DNA and will induce a break in 
that DNA if energized (e.g. with UV light). I can't think of a better 
molecule to pick if you wanted to guess which ones are mutagenic. I don't
need to see extensive epidemiological studies to figure out that a chemical 
that disrupts and nicks DNA can't be a good thing.  

Personally, I've never heard anyone say that it's harmless and as long
as that label on the bottle tells me it's a serious hazard and as long 
as the Occupational Health and Safety office requires me to treat it like 
a potent mutagen, I'm not going to rely on sheep farmers for the information.
Skin cancer ain't my idea of a good time and it seems illogical to me that 
a chemical that nicks DNA in the presence of UV light in the lab won't 
do the same damned thing to me if I get it on myself and go outside. 

Oh yeah, remind me not to eat or wear anything imported from Australia :)


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