MUTAGENS OF POTENTIAL SIGNIFICANCE 173 



of the stomach, where the pH is about 1 in normal individuals, it is 

 obvious that nitrous acid will be formed. How much of that nitrous 

 acid has access to the gonads, we do not know.* But one could easily 

 argue, on the basis of general knowledge already at hand, that nitrites 

 should be forbidden, since other preservatives are presumably available. 



As drugs, nitrites are employed to improve the circulation in certain 

 organs, particularly the heart, and sodium nitrite itself finds use as a 

 long-acting dilator of the blood vessels. At the pH of the blood, 7.4, 

 we may consider that the amount of nitrous acid will be negligible, but 

 again, we must ask what is a negligible amount from the standpoint 

 of mutagenic action. 



Freese: Is it known how nitrite exerts its preservative effect? 



Goldstein: I am not aware of it. It may be known. 



Freese: I mean, could it be the very fact that it is mutagenic? 



Lederberg: 1 think it's a heme poison. 



Goldstein: It is a heme poison in the sense that it produces methemo- 

 globinemia in man, in toxic amounts. It takes quite a bit to do this. 



Magni: Is it for preserving the color of the meat? 



Lederberg: I think it is primarily used as an antibacterial agent. 



Magni: No, it is not bactericidal. E. coli can grow in the presence of 

 1 mol/liter of sodium nitrite in neutral media. 



Goldstein: I think there is no convincing evidence that it is muta- 

 genic. To continue with examples of different types, some drugs have 

 been shown to be mutagenic or to produce chromosome damage with- 

 out any specific functional groups being clearly involved. Atropine, for 

 example, may be cited as representative of a class of complex mole- 

 cules which finds wide use in medicine, which has been shown to have 

 this effect, and in which one has no idea what the mechanisms of 

 mutagenic action may be. 



Motulsky: What are the systems in which they have been shown 

 to be mutagenic? 



Goldstein: It is generally in plant systems, where the criterion is 

 the observation of chromosomes (18). 



Zamenhoj: Wasn't ethylene oxide recently suggested as an agent to 

 sterilize canned food? That would also be a possible mutagen. 



Goldstein: If there is a residual, yes, but that is unlikely. 



Glass: Did you intend to suggest beta-propiolactone, which has been 

 suggested for medical use recently? 



Goldstein: No. Would you like to? 



* Nor, again, whether the higher concentration in contact with the gastric 

 mucosa might be carcinogenic through induction of somatic mutation. 



