MUTAGENS OF POTENTIAL SIGNIFICANCE 197 



comparison of European and American populations. In Europe, no 

 chlorine is added to the drinking water. 



Goldstein: Not so easy, I am afraid, because there are so many 

 other difficulties in obtaining comparable groups. 



Fluoride is also added to water supplies now, at a level of approxi- 

 mately 1 mg/1. This is a level that already exists in many natural 

 water supplies, so some human populations have been exposed through- 

 out the history of the race. The absorption of fluoride is excellent, but 

 its mutagenicity is unknown. 



In the realm of foods and food additives one could spend all day 

 (and I don't propose to do so) talking about the numerous types of 

 chemical compounds to which we are exposed. An example of a food 

 mutagen is mustard seed, which contains the mutagenic allyl iso- 

 thiocyanate (2) . Garlic extracts produce chromosome changes in onion 

 roots (18) ! It is conceivable, as I mentioned at the start, that food 

 habits in certain parts of the world may involve the ingestion of foods 

 containing mutagens in significant amounts, but no data are available 

 about this. 



The addition of substances to food is another matter. Many types of 

 compounds are added to food for various reasons — for buffering, color- 

 ing, preservation, sweetening or emulsifying, flavoring, antibiotics for 

 preservation of meat and poultry, hormones that have been used to 

 fatten the meat animal, and so on (10) . Among all these one finds some 

 compounds which have been shown to be mutagenic under some con- 

 ditions, or are closely related to others that are mutagenic. But, on the 

 whole, the amounts added are extremely small. In the case of the coal 

 tar dyes, increasing evidence of carcinogenicity has led to their prac- 

 tical outlaw in foods. Nitrite is a distinct hazard already discussed. 



Insecticides are used in the treatment of crops and fruits. The Food 

 and Drug Administration tolerance limit is zero for residual insecticide, 

 so that present intake may be disregarded, at least in this country. 

 On the other hand, an insecticide like DDT is widely absorbed into the 

 fatty tissues of meat animals and is present in the milk of dairy cattle 

 exposed to DDT. As a matter of fact, autopsies on human subjects 

 have shown that we all have measurable amounts of DDT in our 

 depot fat. Thus exposure to this insecticide is quite general. But noth- 

 ing is known about its mutagenicity. 



Aminotriazol, the compound that figured in the 1959 cranberry 

 scare, was shown to have carcinogenic activity, but its mutagenicity is 

 unknown. 



There is a group of industrial air pollutants that should be men- 



