But we ought to be exceedingly cautious about accepting any definite figure, certainly any large figure, as representing the permissible amount of added benzoic acid in our food. The very fact that we are in possession of an efficient process for converting poisonous benzoic acid into harmless hippuric acid indicates that there is a necessity for doing so. It suggests that even the small quantities of benzoic acid which we get with unadulterated food, or produce within ourselves, might be deleterious to health except for the saving hippuric acid forming process. And because that "factor of safety" is a large one with respect to the normal benzoic acid content of our food it does not follow that we can encroach on it with perfect impunity. What the effect of a general, regular encroachment on it would be cannot be determined by a few relatively short feeding experiments. It is known that while certain chemicals may be taken in substantial quantities for a month or a year without producing demonstrably injurious effects, nevertheless the continued use of the same substances, even in smaller quantities, will eventually undermine the health. Perhaps the final solution of the benzoic acid problem could be best obtained directly from the people at large. If they were to consume benzoic acid as knowingly as they consume, for example, sodic carbonate in soda biscuits, or caffeine and theobromine in coffee and tea, it would not require more than a decade or two before we should have a well-defined and well-founded public opinion on the subject, at least in the medical profession.[46]
With respect to other familiar and more or less poisonous substances used to preserve foods, defense of their harmlessness is far more difficult. Formaldehyde, salicylic acid, sulphurous acid, and sulphite are compounds definitely poisonous in relatively small amounts, their injurious action in minute successive doses in animal experiments is quite marked, and their use in human food products practically without justification. Boric acid and borax are perhaps on a slightly different footing, but are never present in natural foods, and there is no good evidence that their long-continued ingestion in small doses is without injurious effect. It must not be forgotten that all such substances owe their preservative or antiseptic power to the poisonous effect they have upon bacterial protoplasm. It is fair to assume that, in general, bacterial protoplasm is no more easily injured than human protoplasm, and this raises at once the propriety of bringing into repeated contact with human tissues substances likely to produce injury even if such injury is slight and recovery from it is ordinarily easy. In every case the burden of proof should be properly placed on those who advocate the addition of bacterial-restraining substances to food intended for human consumption. It is for them to show that substances powerful enough to hold in check the development of bacteria are yet unable to interfere seriously with the life-processes of the cells of the human body.
When this view of the situation is taken, not only the chemical substances mentioned previously fall under some suspicion, but also certain household preservatives long sanctioned by custom. Spices such as cinnamon, oil of cloves, and the like are, so far as we know, as likely to have an injurious physiological effect when taken in small recurring quantities as are some of the "chemical" preservatives whose use is debarred by law. The chemicals deposited by wood smoke in meat are of a particularly objectionable nature, and their continuous ingestion may quite conceivably lead to serious injury.
One fact persistently comes to the front in any comprehensive study of the food-preservative question, namely, the need of further experiment and observation. We do not at present know what effect is produced in human beings of different ages and varying degrees of strength by the long-continued consumption of food preserved with particular chemicals.
There is, I think, only one way to get at the facts with regard to the various chemicals which have been used for the preservation of foods, and that is by trying them and keeping track of the results. To try them properly, on a sufficiently extensive scale and for a sufficiently long time, is, however, more of a task than can be undertaken by private investigators; for it is only by their continuous use for many years under competent supervision and control that we can hope to attain adequate information for final conclusions. Work of this sort should be done and could very well be done at large government institutions, as, for example, among certain classes of prison inmates. I do not know how many life prisoners or long-term prisoners may be available, but there must be an abundance of them. They would make better subjects than students on whom to try out a substance like boric acid. This, not because they are prisoners whose fate or health is of comparatively little consequence, but because they represent a body of persons whose mode of life is essentially uniform and whose health record could easily be kept for a long period of years. I am well aware that this suggestion will impress many persons as heartless and brutal, but such an experiment would be a mild and humane one when compared with the unrecorded boric acid experiments which have been made by manufacturers on all kinds and conditions of people. Prisoners are unfortunate in not being able to render any useful service to society. Probably not a few would be willing to co-operate in prolonged feeding experiments, similar to the short ones conducted by Dr. Wiley and by the Referee Board. Acceptable reward in the way of well-prepared food of sufficient variety would attract volunteers. If additional inducement were necessary, shortened term of service would probably appeal to many. And in the face of the fact that every civilized country is prepared to sacrifice thousands of its most virile citizens for the honor of its flag (and its foreign trade), the sentiment against endangering the health of a handful of men in the interest of all mankind is not particularly intelligent.[47]
Until such information is forthcoming we do well to err on the side of caution. The desirability of adopting this attitude is especially borne in upon us by the facts already instanced (pp. [2]-[4]) concerning the increased death-rates in the higher-age groups in this country. For aught we now know to the contrary, the relatively high death-rates from degenerative changes in the kidneys, blood vessels, and other organs may be in part caused by the use of irritating chemical substances in food. Although no one chemical by itself and in the quantities in which it is commonly present in food can perhaps be reasonably accused of producing serious and permanent injury, yet when to its effect is superadded the effect of still other poisonous ingredients in spiced, smoked, and preserved foods of all kinds the total burden laid upon the excretory and other organs may be distinctly too great. There can be no escape from the conclusion that the more extensive and widespread the use of preservatives in food the greater the likelihood of injurious consequences to the public health.
The use of spoiled or decomposed food falls under the same head. It cannot be assumed that the irritating substances produced in food by certain kinds of decomposition can be continually consumed with impunity. We do not even know whether these decomposition products may not be more fundamentally injurious than preservatives that might be added to prevent decomposition!
So far as our present knowledge indicates, therefore, effort should be directed (1) to the purveying of food as far as possible in a fresh condition; (2) to the avoidance of chemical preservatives of all kinds except those unequivocally demonstrated to be harmless. The methods of preserving food by drying, by refrigeration, and by heating and sealing are justified by experience as well as on theoretical grounds, and the same statement can be made regarding the use of salt and sugar solutions. But the use of sulphites in sausage and chopped meat, the addition of formaldehyde to milk, and of boric acid or sodium fluoride to butter are practices altogether objectionable from the standpoint of public health.
The remedy is obvious and has been frequently suggested—namely, laws prohibiting the addition of any chemical to food except in certain definitely specified cases. The presumption then would be—as in truth it is—that such chemicals are more or less dangerous, and proof of innocuousness must be brought forward before any one substance can be listed as an exception to the general rule. Such laws would include not only the use of chemicals or preservatives, but the employment of substances to "improve the appearance" of foodstuffs. As already pointed out, the childish practice of artificially coloring foods involves waste and sometimes danger. It rests on no deep-seated human need; food that is natural and untampered with may be made the fashion just as easily as the color and cut of clothing are altered by the fashion-monger. The incorporation of any chemical substance into food for preservative or cosmetic purposes could wisely be subject to a general prohibition, and the necessary list of exceptions (substances such as sugar and salt) should be passed on by a national board of experts or by some authoritative organization like the American Public Health Association.