CHAPTER IV

MINERAL OR ORGANIC POISONS ADDED TO FOOD

Well-known mineral or organic poisons--"chemical poisons"--sometimes find their way into food, being either introduced accidentally in the process of manufacture or preparation, or being added deliberately with intent to improve the appearance or keeping qualities of the food.

ARSENIC

So powerful a poison as arsenic has been occasionally introduced into food by stupidity or carelessness. Arsenic has been found by English authorities to be generally present in food materials dried or roasted with gases arising from the combustion of coal, and in materials treated with sulphuric acid during the process of preparation. In both cases the source is the same: the iron pyrites, practically always arsenical, contained in the coal or used in making the sulphuric acid.

A celebrated epidemic of "peripheral neuritis" in the English Midlands in 1900 was traced to the presence of dangerous quantities of arsenic in beer. About six thousand persons were affected in this outbreak and there were some seventy deaths. The beer coming from the suspected breweries had all been manufactured with the use of brewing sugars obtained from a single source, and these sugars were found to have been impregnated with arsenic by the sulphuric acid used in their preparation, some specimens of the acid containing as much as 2.6 per cent of arsenic.[32]

The use of glucose, not only in beer, but as an admixture or adulterant in jams, syrups, candies, and the like, is open to serious objection unless the glucose is known to have been prepared with sulphuric acid freed from arsenical impurity. In fact, the use of any food material prepared by the aid of sulphuric acid is permissible only in case arsenic-free acid is employed.[33]

ANTIMONY

The cheaper grades of enameled cooking utensils in use in this country contain antimony, and this is dissolved out in noteworthy amounts in cooking various foods.[34] The rubber nipples used for infants' milk bottles also sometimes contain antimony.[35] Although the poisonous qualities of antimony are well known, there is little information about the toxic effect of repeated very minute doses. Recognized instances of chronic antimony poisoning are very rare. Further investigation is needed.

LEAD

The well-known poisonousness of lead and its compounds prevents, as a rule, the deliberate addition of lead salts to food substances, although it is true that lead chromate is sometimes used for imparting a yellow color to candy and decorating sugars.[36] Foods that are wrapped in foil, however, such as chocolate and soft cheese, contain traces of lead, as do the contents of preserve jars with metallic caps and the "soft drinks" vended in bottles with patent metal stoppers. Occasional ingestion of minute quantities of lead is probably a matter of little physiological importance, but since lead is a cumulative poison, frequent taking into the body of even very small amounts entails danger. Severe lead poisoning has been known to result from the habitual use of acid beverages contained in bottles with lead stoppers. Investigations made to determine the possible danger of poisoning from lead taken up from glazed and earthenware cooking utensils indicate that injury from this source is unlikely. The enameled ware in common use in this country is lead-free.

Objection on the ground of possible contamination has been raised to the use of solder for sealing food cans. Such objections have less weight than formerly owing to changes in the construction of the container, so that any contact of solder with the food is now minimized and to a large extent done away with altogether.

In consequence of the fact that many natural waters attack lead, the use of lead service pipes for wells, cisterns, and public water supplies has given rise to numerous outbreaks of lead poisoning. It is now generally recognized that water intended for drinking purposes should not be drawn through lead pipes.

A special liability to take lead into the stomach exists in persons working at the painters' trade and other occupations involving contact with lead and its salts. It has been shown that the eating of food handled with paint-smeared hands brings about the ingestion of considerable quantities of lead and, when long continued, results in lead poisoning. The risk of contaminating food with lead in this way can be greatly lessened by thorough cleansing of the hands with soap and hot water before eating.[37]

TIN

Special interest has attached to the possibility of tin poisoning on account of the widespread use of canned foods.[38] It is established chemically that tin is attacked, not only by acid fruits and berries, but by some vegetables having only a slightly acid reaction. More tin is found in the drained solids than in the liquor, and the metal is largely in an insoluble form.[39] It has been the general opinion based on experiments by Lehmann[40] and others that the amounts of tin ordinarily present in canned foods "are undeserving of serious notice," and this view has found expression in the leading textbooks on hygiene.[41] Certainly there has not been any noticeable amount of tin poisoning observed coincident with the enormous increase in the use of canned foods. An instance of poisoning by canned asparagus observed by Friedmann,[42] however, is attributed by him to the tin content, and this view is rendered probable by the negative result of his bacteriological and serological examinations. Canned asparagus apparently contains an unusually large amount of soluble tin compounds.[43] There seems some ground for the assumption that certain individuals are especially susceptible to small quantities of tin and that the relative infrequency of such cases as that cited by Friedmann can be best explained in this way. Lacquered or "enamel-lined" cans are being used to an increasing extent for fruits and vegetables that are especially likely to attack tin.[44]

Intentional addition of tin salts to food substances does not appear to be common, although protochloride of tin is said sometimes to be added to molasses for the purpose of reducing the color. The chlorides are regarded as more definitely poisonous than other compounds of tin, and for this and other reasons the practice is undesirable. Sanitarians insist that chemical substances likely to be irritating to the human tissues in assimilation or elimination should not be employed in food. Each new irritant, even in small quantity, may add to the burden of organs already weakened by age or previous harsh treatment.

COPPER

Danger is popularly supposed to attend the cooking and especially the long standing of certain foods in copper vessels on account of the verdigris or copper acetate that is sometimes formed, but Professor Long, of the Referee Board of Consulting Scientific Experts,[45] points out that this substance is far less toxic than it was once imagined to be, and he considers it likely that the cases of illness attributed to "verdigris poisoning" reported in the older literature should have been explained in some other way.

The use of copper sulphate for imparting a green color to certain vegetables, such as peas, beans, and asparagus, is a relatively modern practice, having been started in France about 1850. Since the natural green of vegetables is in part destroyed or altered by heat, restoration of the color has appealed to the color sense of some consumers. It must be admitted that this aesthetic gratification is fraught with some degree of danger to health. The experiments by Long show that copper is absorbed and retained in certain tissues, and that even small amounts ingested at brief intervals may have a deleterious action. He concludes that the use of copper salts for coloring foods must be considered as highly objectionable. The United States Government now prohibits the importation of foods colored with copper and also the interstate trade in these substances.

VARIOUS COLORING SUBSTANCES

Copper sulphate is but one of a host of chemical substances applied to various foods for the purpose of altering the color which the foods would otherwise possess. In some cases perhaps it may be the general opinion that by special treatment the attractiveness of a food product is increased, as when dark-colored flour is bleached white with nitrogen peroxide, but in many instances the modification of color is based on preposterously artificial standards. The use of poisonous aniline dyes for staining candies all the colors of the rainbow must be defended, if at all, on aesthetic rather than on sanitary grounds. Some coloring matters in common use, such as the annatto, universally employed in coloring butter, are believed to be without harmful effect, but others are to be viewed with suspicion, and still others, like copper sulphate, are unquestionably dangerous. The whole practice of food coloration at its best involves waste and may entail serious danger to health. Broadly speaking, all modification of the natural color of foodstuffs is based on an idle convention and should be prohibited in the interest of the public welfare. Bleached flour, stained butter, dyed jelly and ice-cream are no whit more desirable as foods than the natural untreated substances; in fact, they are essentially less desirable. If the whole process of food coloration were known to the public, artificially colored foods would not be especially appetizing. Economically the practice is singularly futile. The artificial whitening of flour with the highly poisonous nitrogen peroxide seems hardly worth the extra tax of fifty cents to a dollar a barrel. Such bleaching with a poisonous gas certainly does not improve the nutritive or digestive qualities of flour; it may be insidiously injurious. The solution of the problem of food coloration seems to lie in a policy of educational enlightenment which shall make natural foods appear more desirable than those sold under false colors. Custom, however, buttressed by skilful advertising, offers a difficult barrier to reform in this field.

FOOD PRESERVATIVES

It is not only legitimate, but in every way most desirable, to keep food over from a season of superabundance to a season of scarcity. From time immemorial food has been preserved by drying, smoking, or salting, and, in modern times, by refrigeration and by heat (canning). These latter methods have come to play a large part in the food habits of civilized communities. Since food spoils because of microbic action, all methods of preservation are based upon the destruction of the microbes or the restraint of their growth by various physical and chemical agencies. The use of certain chemical preservatives such as strong sugar and salt solutions, saltpeter brines, and acid pickles has long been known and countenanced. In recent times the employment of chemical preservatives has acquired a new aspect through the increasing tendency of manufacturers to add to food products antiseptic chemicals in wide variety and of dubious physiological effect.

It is not so easy and simple as it might appear to declare that no substance that is poisonous shall be added to food. The scientific conception of a poison is one involving the amount as well as the kind of substance. Common salt itself is poisonous in large doses, but, as everyone knows, small amounts are not only not injurious, but absolutely necessary to health. Well-known and very powerful protoplasmic poisons such as strychnine and quinine are frequently administered in minute doses for medicinal purposes, without causing serious results.

How complicated the question of using food preservatives really is appears in the case of smoked meats and fish, which owe their keeping qualities to the creosote and other substances with which they are impregnated by the smoke. Although these substances are much more highly poisonous than chemical preservatives like benzoic acid, over which much concern has been expressed, but little if any objection has been made to the use of smoked foods.

The use of benzoic acid (benzoate of soda) as a food preservative illustrates several phases of the controversy. Observations by Wiley in 1908 upon so-called "poison squads" were thought by him to indicate that benzoate of soda administered with food led to "a very serious disturbance of the metabolic functions, attended with injury to digestion and health." On the other hand, the experiments of the Referee Board of Scientific Experts (1909), conducted with at least equal care and thoroughness, were considered to warrant the conclusions that:

(1) Sodium benzoate in small doses (under five-tenths of a gram per day) mixed with the food is without deleterious or poisonous action and is not injurious to health. (2) Sodium benzoate in large doses (up to four grams per day) mixed with the food has not been found to exert any deleterious effect on the general health, nor to act as a poison in the general acceptance of the term. In some directions there were slight modifications in certain physiological processes, the exact significance of which modification is not known. (3) The admixture of sodium benzoate with food in small or large doses has not been found to injuriously affect or impair the quality or nutritive value of such food.

Still later experiments under the auspices of the German government (1913) showed that in the case of dogs and rabbits relatively large doses of benzoic acid (corresponding to sixty to one hundred grams per day for a man weighing one hundred and fifty pounds) were necessary in order to produce demonstrable effects of any kind. This finding may be considered to confirm in a general way the finding of the Referee Board that four grams per day is harmless.

Probably the evidence respecting the effect of benzoic acids and the benzoates when used as food preservatives constitutes as favorable a case as can be made out at the present time for the employment of any chemical substance. Benzoic acid is present in noteworthy amounts in many fruits and berries, especially cranberries, and its presence in these natural foods has never been connected with any injurious action. In point of fact, substances present in many ordinary foodstuffs are converted within the human body first into benzoic acid and then into hippuric acid. Folin's masterly summing up is worth quoting:

We know that the human organism is prepared to take care of and render harmless those small quantities of benzoic acid and benzoic acid compounds which occur in food products or which are formed within the body; we know how this is accomplished and are reasonably sure as to the particular organ which does it. We also know that the mechanism by means of which the poisonous benzoic acid is converted into the harmless hippuric acid is an extremely efficient one, and that it is capable of taking care of relatively enormous quantities of benzoic acid. In this case, as in a great many others, the normal animal organism is abundantly capable of performing the function which it must regularly perform in order to survive. From this point of view it can be argued, and it has been argued with considerable force, that the human organism is abundantly capable of rendering harmless reasonable amounts of benzoic acid or benzoate which are added for purposes of preservation to certain articles of our food. In my opinion this point of view is going to prevail, and the strife will resolve itself into a controversy over how much benzoic acid shall be permitted to go into our daily food.

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.

FOOD SUBSTITUTES

On grounds of economy or convenience familiar and natural articles of food are sometimes replaced or supplemented by artificial chemical products, or by substances whose food value is not so definitely established. I need refer only briefly to those notorious instances of adulteration in which chicory is added to coffee, or ground olive stones to pepper, or glucose to candy. On hygienic grounds alone some such practices are not open to criticism, however fraudulent they may be from the standpoint of public morals. It might be argued with some plausibility that chicory is not so likely to harm the human organism as caffeine and that sprinklings of ground cocoanut shell are more wholesome than pepper. But there is another group of cases in which the artificial substitute is strictly objectionable. The use of the coal-tar product saccharin for sweetening purposes is an example. This substance, whose sweetening power is five hundred times as great as that of cane sugar, has no nutritive value in the quantities in which it would be consumed, and in not very large quantities (over 0.3 gram per day) is likely to induce disturbance of digestion. As a substitute for sugar in ordinary foodstuffs it is undesirable.[48]

The use of cheap chemically prepared flavors such as "fruit ethers" in "soft drinks," fruit syrups, and the like in place of the more expensive natural fruit extracts affords another well-known instance of substitution. Probably more important hygienically is the production of "foam" in "soda water" by saponin, a substance known to be injurious for red blood corpuscles.

Among the many other familiar examples of food substitution, sophistication, and adulteration there are some of demonstrable hygienic disadvantage and others whose chief demerit lies in simple deception. Of practically all it may be said that they are indefensible from the standpoint of public policy since they are based on the intent to make foodstuffs appear other than what they really are.

It is the opinion of some who have closely followed the course of food adulteration that, while the amount of general sophistication--legally permissible and otherwise--has greatly increased in recent years, the proportion of really injurious adulteration has fallen off. Be that as it may, it is plain that the opportunity for wholesale experimentation with new substances should not be allowed to rest without control in the hands of manufacturers and dealers largely impelled by commercial motives. So long as the motive of gain is allowed free scope, so long will a small minority of unscrupulous persons add cheap, inferior, and sometimes dangerous ingredients to foodstuffs. The net of restriction must be drawn tighter and tighter. The motives leading to the tampering with food fall mainly under three heads: (1) a desire to preserve food from spoiling or deterioration; (2) a puerile fancy--often skilfully fostered for mercenary reasons--for a conventional appearance, as for polished rice, bleached flour, and grass-green peas; and (3) intent to make the less valuable appear more valuable--deliberate fraud. Only the first-named motive can claim any legitimate justification, and its gratification by the use of chemical preservatives is surrounded with hygienic difficulties and uncertainty, as already set forth. From the unbiased view of human physiology the dangers of slow poisoning from chemically treated foods must be regarded as no less real because they are insidious and not easily traced.

FOOTNOTES:

[32] E. S. Reynolds, _Lancet_, I (1901), 166.

[33] The sulphuric acid used in making glucose in the United States is authoritatively declared to be absolutely free from arsenic (report of hearing before Illinois State Food Standard Commission, June 21-23, 1916; see _Amer. Food Jour._, July, 1916, p. 315).

[34] E. W. Miller, _Jour. Home Economics_, VIII (1916), 361.

[35] Phelps and Stevenson, _Hyg. Lab., U.S. Public Health Service, Bull. 96_, 1914, p. 55.

[36] Harrington and Richardson, _Manual of Practical Hygiene_, 5th ed., p. 224.

[37] See Alice Hamilton, "Hygiene of the Painters' Trade," _U.S. Bureau of Labor Statistics, Bull. 120_, 1913.

[38] In 1909 the value of foods canned in the United States amounted to about $300,000,000 (_U.S. Dept. of Agric., Bull. 196_, 1915).

[39] W. D. Bigelow, _Amer. Food Jour._, XI (1916), 461.

[40] _Arch. f. Hyg._, XLV (1902), 88; _ibid._, LXIII (1907), 67.

[41] See, e.g., Harrington and Richardson, _Practical Hygiene_, 5th ed., p. 274.

[42] _Ztschr. f. Hyg._, LXXV-LXXVI (1913-14), 55.

[43] Bigelow, _loc. cit._

[44] A. W. Bitting, _U.S. Dept. of Agric., Bull. 196_, 1915.

[45] _U.S. Dept. of Agric., Report 97_, 1913.

[46] Folin, _Preservatives and Other Chemicals in Foods_ (Harvard University Press, 1914), p. 32.

[47] Folin, _op. cit._, p. 42.

[48] See _U.S. Dept. of Agric., Report 94_, 1911.