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.