Ames test: Ethidium bromide

Celedonio González cglez at
Wed Jul 18 10:48:36 EST 2001

>I had a quick look in:
>McCann J, Choi E, Yamasaki E and Ames B, PNAS (1975), Vol 72, 5153
>"Detection of carcinogens as mutagens in the Salmonella/microsome test:
>Assay of 300 chemicals"
>(that being the only EtBr mutagenicity reference I could get hold of
>easily). [Kudos to Roland Hübner, whose post spurred me to look it up].
>EtBr scores as 1012 revertents/5ug ethidium bromide tested, which is
>high (assayed in presence of liver homogenate, ie after metabolic
>Compare to 18200 revertents/(single cigarette smoke condensate).

Can we trust these numbers?

Assuming these numbers are good indicators of mutagenicity and
carcinogenicity. And assuming a linear relationship between these two factor
and the quantity of carcinogen. Then eating a EtBr-containing 18 x 20 x 0.5
cm gel would be as harmful as smoking a single cigarette, since the gel
would contain 90 micrograms of EtBr (at the usual 0.5 microgram/ml
concentration), the quantity needed to generate as much revertants as the
smoke of a single cigarette.

Celedonio Gonzalez


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