# Popular Science Monthly/Volume 73/August 1908/A Bacteriological Study of Soiled Paper Money

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* A BACTERIOLOGICAL STUDY OF SOILED PAPER MONEY
By WARREN W. HILDITCH
THE SHEFFIELD LABORATORY OF BACTERIOLOGY AND HYGIENE, YALE UNIVERSITY
IT is generally acknowledged to-day that little progress can be made in sanitation or hygiene without the general cooperation of the public. To obtain this cooperation, it is essential that the people be correctly informed upon all sanitary or hygienic subjects; for should it be found that the demands for this or that improvement are not based upon true scientific facts, how can success be hoped for, when a really essential reform is brought forth?
All will agree that soiled paper money is at least not a thing of beauty, and the unpleasant odors and filth accompanying some bills offend every esthetic sense, and give good foundation for the demand for a more frequent issue or redemption of our currency by the government. Everybody who has traveled abroad will admit that our paper currency is a disgrace when compared to the clean, crisp money to be found in many of the foreign countries, where soiled or worn bills are almost unknown.
In our arguments for clean money, should we include the one which claims that soiled paper money is a frequent medium for the transmission of infectious diseases? The popular opinion to-day is that paper money is very filthy and extremely dangerous to handle, as on it may be found any and all kinds of disease germs known to science. Many people, especially women, have a dread and horror of dirty money and often insist on clean bills when getting change; yet cashiers and bank tellers very seldom think of the filth on the money, and they have no aversion for it. Physicians often seem eager to blame our currency for the spread of disease or the cause of death, especially when it is difficult to find out the true source of infection.
The frequent occurrence of diphtheria and tuberculosis led me to be especially interested in attempts to find Bacillus diphtheriæ and the tubercle bacillus on money, and thus prove it to be one medium for the transmission of these diseases. The soiled money used for this study was the dirtiest I could obtain from various sources, such as railroad, trolley and theatre ticket offices, banks, drug stores and individuals in different parts of the state. Some of the bills were much more worn than others, being very soft, cracked and soiled, with frayed edges.
Each bill was thoroughly brushed in twenty-five cubic centimeters of sterile physiological salt solution, the work being carried on under ​a glass jar to avoid contamination from the air. In order to estimate the number of bacteria present, 0.5 c.c. of this wash water were diluted with 10 c.c. of physiological salt solution and three series of agar plates were poured, using 0.2, 0.3 and 0.5 c.c. of this dilution. The wash fluid was then measured and centrifugated, the coarse particles of dirt and paper thus thrown down were filtered off and the fluid again centrifugated. With the sediment of bacteria and fine dirt obtained in this manner, I inoculated three bouillon tubes in order to look for streptococci and other forms that might develop. Ten tubes of serum were smeared for the detection of Bacillus diphtheriœ, while the rest of the sediment was then carefully injected subcutaneously into a guinea pig. The animals were closely observed for several days so that in case of a fatality an autopsy could be performed immediately after death and the lesions thus more correctly observed. All media used for this experiment were prepared according to the standard method of the American Public Health Association, with a final reaction of +0.8 (0.8 per cent. acid).
At first I intended to make a study of only twelve bills, since it required a full week to complete the study of each bill; but the appearance in the daily press of accounts of the present agitation for clean money led me to make a total of twenty-four examinations. In twenty of these all the sediment was injected into guinea pigs, in order to allow the development of tuberculosis or septicæmias that might be caused by the bacteria in the sediment; in the other four, the sediment was used for smearing serum plates to detect Bacillus diphtheria.
It was surprising to find the flora so constant, Staphylococcus pyogenes alius being by far the most common form present, with various members of the subtilis group next; Staphylococcus pyogenes aureus was found on all bills, but not in large numbers. The following were found on some bills, but always few in number; Staphylococcus cereus albus, a streptothrix, Sarcina lutea, streptococci and in one instance, Bacillus xerosis. Other chromogenic bacteria were frequently found but not identified.
The numbers of bacteria present on the bills ranged from 14,000 up to 586,000, with an average for twenty-one bills of 142,000. There seemed to be no connection between the amount of dirt and the number of bacteria present; the cleanest-looking bill that I used had next to the highest count (405,000), while the bill that looked the dirtiest had but 38,000. When a bill has been in circulation for a short time and has become somewhat cracked, and its peculiar glaze worn off, the bacteria very easily cling to it without the presence of dirt and grease.
All inoculations gave negative results, the time limit being placed at from six to seven weeks. All of the guinea pigs showed more or less local reaction, with swelling of the lymph glands of the groin, but ​none gave any indication of even temporary illness. Inoculations of pure cultures of staphylococci, as well as of Bacillus verosis (which was at first suspected of being Bacillus diphtheria;) also gave negative results.
From the observations that I have made, it would seem that the bacteria present on paper money are non-virulent and the forms most common are the air forms. Could the loss of virulence be due to drying, the bills having a peculiar dry feeling, no matter how moist the air; or is there some antiseptic action in the ink used for the printing of the bills? I have not taken up the question as to why the bacteria found on money are without virulence, but have confined this study to a careful search for pathogenic forms that might be present on the bills.
The literature on this subject is exceedingly scanty. I have been unable to find any report upon any good scientific work done along this line. Inquiry at the Congressional Library at Washington revealed only four articles—one in Spanish, one in German and two in English, while inquiry among a number of scientific men failed to give me any further assistance with the literature upon the subject of the transmission of infectious diseases through paper money.
That the interest in dirty money, or desire for clean money, is not of recent origin is shown in an article by Dr. Otto Müller, which appeared in 1879. He suggests that money is one means of transmitting the infectious diseases, and although it is extremely difficult to prove an actual case, it certainly offers possibilities. He lays particular emphasis upon the pernicious habit of giving coins to children to play with, especially when they are sick; and also the habit of keeping money under bed pillows, or in commodes or closets where linen or food is kept.
Drs. Acosta and Rossi reported in a Havana journal the results of bacteriological examinations of bank notes made by them. They examined two bills that had been in circulation for some time and found them loaded with germs of various kinds and degrees of malignancy. Cultures were made from the scrapings of the notes and these were injected into the peritoneal cavity of rats and guinea-pigs, most of which died within twenty-four hours, the post-mortem examinations showing signs of peritonitis and congestion of the liver and kidneys. They did not identify any of those germs having "various degrees of malignancy." The fact that the animals died within twenty-four hours indicates that death was not due to the action of any one or more pathogenic forms that might have been present, but rather to the great numbers of bacteria suddenly thrown into the peritoneal cavity.
​Fifteen years ago Dr. J. C. Graham, of Columbus, Ohio, carried on a study of soiled paper money, to furnish data to be used as the basis of a bill placed before Congress for a more frequent redemption of damaged paper currency. He examined fourteen bills, simply shaking them in 50 c.c. of distilled water and adding portions (0.1 c.c.) of this wash fluid to gelatin, for plating.
Agar was used twice, with resulting growth only once; but the author presumes that not all microbes present developed, since many pathogenic forms, especially Bacillus diphtheriæ? and the tubercle bacillus, will not grow at a temperature much below that of the body, or on the media used. He was able to recognize only Bacillus subtilis. To determine the pathogenic characteristics, only two inoculations were made; a twenty-four hour bouillon culture of an unknown bacillus was injected subcutaneously, into a full-grown rabbit, with negative results, excepting a slight rise of temperature. For the second inoculation, the wash fluid from a bill was placed in the incubator for forty-eight hours, and fifteen minims of this were injected into the peritoneal cavity of a rabbit, with negative results. He usually found only two or three species, but in one case claimed to have found five; three bacilli, one of them a spore form, an ordinary micrococcus and a diplococcus. One bill he estimated to have the enormous number of 901,320,000 bacteria upon it. He sums up his article by saying that "Money may be a source of danger by transmitting diseases."
Personally, I can not see that the object of Graham's study was accomplished, for no data were given which could support a bill for a more frequent redemption of our paper currency. The author himself saw the faults of his experiments when he presumed that not all bacteria present developed, especially since the ones in which he was most interested, the pathogenic forms, particularly, Bacillus diphtheria and the tubercle bacillus, would not grow at a temperature much below that of the body or on the media used; yet he did not attempt to overcome these faults.
In Revista Medica de Bogota of July, 1904, there is an article on "The Spread of Infectious Diseases by Paper Money." The author (his name was not given) suggests that the rapid increase of leprosy, in a certain locality during the past three years, may be due to the money in circulation, and he suggests a special currency for lepers. A bacteriological study was made by macerating some bills (twenty) in sterile, distilled water and allowing the wash to stand two or three days in a cylinder. The sediment was pipetted off and smears of it examined. The only germ identified was Bacillus subtilis, though ​three or four other species were observed. No animal inoculations were made.
Writing on "Money as a Carrier of Infection," in 1895, C. I. Wendt says: "A thoughtful man and careful student will want some positive information on this subject." He reports upon the experiments of Professor Bolton, on coins, showing that when a coin is placed in the center of a sterile Petri dish, and agar which has been inoculated with pathogenic organisms is poured over it, the medium immediately surrounding the coin reveals no growth, but remains sterile, due to the slight solution of copper, as shown by the potassium ferro-cyanide reaction. These experiments should prove of some interest and value by setting at rest any fears which might have been entertained as to the power of coins to act as carriers of disease germs, and by reason of grease and dirt on them, to allow of bacterial growth.
Thus we see that this subject has received no truly scientific study, and those investigations that have been made show little or no merit. Of the various forms of bacteria found upon the dirty bills only Bacillus subtilis was identified, and no trace of any pathogenic forms could be found, through either cultures or animal experiments. Inoculations were made in only a few cases, and these all proved negative. In the study upon coins no attempt was made to find what forms of bacteria are common on them, and the results given above do not show coins to be incapable of carrying disease germs, but merely indicate that coins placed in certain media yield enough copper for solution to prevent the growth of bacteria. Coins, as we handle them, do not usually have moisture upon them, and the dry alloy has no antiseptic action; so we should expect to^ find some bacteria upon coins, as on the bills.
My attention was first called to the present agitation for clean money by articles appearing in the New Haven Register and other papers, some weeks after the beginning of this study. Reference was made to "Clean Money Morrison," whom I found on inquiry to be A. Cressy Morrison, of New York, and the origin of all the articles in the daily press and magazines of the country, to be his pamphlet "Clean Money—Can We Have It? If Not, Why?" Inquiring of Mr. Morrison for reference to any work that he might have done along this line, I was referred to an enclosed copy of his pamphlet and circular letter. This pamphlet was "offered to a carefully selected list of 1,000 of the leading newspapers and magazines of the country, . . . and, with a view to the great value of simultaneous publication, a date of release was placed upon the article, . . . it being presented for editorial comment, judgment and criticism, with the hope that all or part of it be printed."
​Further quotation from this circular letter aptly describes this recent agitation: "There has been much talk on the subject, but no 'do,'" for Mr. Morrison gives no experimental evidence as a basis for this agitation, but says "the statistics regarding germs and microbes found on coins and bills are from one of the most eminent chemists of New York/' who, at the instance of Mr. Morrison, made an especial investigation and found that money is one of the most effective ways by which contagious diseases are disseminated, especially loathsome diseases and "the white man's plague."
The statistics, as given, are from the Research Laboratory of the Board of Health of New York; pennies averaged 26 living bacteria each; dimes, 40; moderately clean bills, 2,250, and dirty bills, 73,000 living bacteria each. In order to have these statistics at first hand, I wrote to Dr. Park, of the Research Laboratory, who informed me that the only study made upon bacteria on money, in his laboratory, was completed some years ago. He also said: "We found paper money to be similar to other paper and rags and capable of carrying living tubercle and diphtheria bacilli for some days or longer. We have never found any evidence whatever of the actual transfer of disease through money."
Mr. Morrison outlines clearly his plan for clean sanitary bills and coins: (1) a much larger issue by the government of bills of small denominations, so that there shall be plenty of new money to redeem the old; (2) free registry of all bills sent to the treasurer of the United States for redemption; (3) the establishment in all states of central government stations to which money may be sent by all banks to be cleansed and polished; (4) the antiseptic cleansing by all banks, stores and corporations, of all coins and bills passing through them; and last, that every individual cleanse and disinfect all money which he receives.
I certainly agree with Mr. Morrison that the government should issue enough new bills of small denominations to replace the old, and that it would be a good plan to allow the people to cooperate in the redeeming of the old bills by making the registry of all bills sent to the treasurer for redemption, free. As for the establishment in all states of government stations for cleansing money, would the expense involved be justified, when we consider that not a single case is on record where an infectious disease has been transmitted through soiled money? Is there any method known whereby we can sterilize a stack of tightly bound bills; or will each bill be sterilized separately, perhaps by being spread on a continuous belt passing through a disinfecting solution? And would not the process of sterilization greatly diminish the (non-bacterial) "life" of a bill?
When one bank official of New Haven was informed about the suggestion that banks, stores and corporations should sterilize all money ​that passed through them, he asked, "What good would it accomplish to sterilize the same bill two or three times a week? It is surprising how frequently a bill returns to the bank. It is given to one depositor, who uses it for change; soon another depositor obtains it through trade, and when the next deposit is made the bill may again find itself within the same bank."
With a more frequent redemption of soiled money, all these suggestions for such cleanliness and the formation of clean money-clubs may be avoided, and particularly if we learn to keep our fingers away from our mouths both while and after counting money.
Very few people realize the expense and work involved in the redemption of soiled money. Many banks to-day go to great expense and trouble in redeeming soiled and worn bills in order to have crisp, new ones on hand when the demand is made for them. Bankers and business men do not prefer these crisp, new bills, for they can not be counted with as much speed and accuracy as those that have been in circulation for some time. Some banks deposit all their soiled and worn bills with another bank, and thus avoid the expense involved in redeeming them.
All money for redemption must be sorted, so that all bills of one denomination are together; and each denomination must have the various species sorted, such as gold and silver certificates, United States and "coin" notes, etc., while national bank notes must be kept separately. Each package must be labeled with its face value and the words "currency for redemption." National banks pay the express charges on their notes one way, while on all other currency the sender pays the charges both ways. The expense involved is not merely the time taken for sorting the bills or the express rate of forty cents per $1,000, but also the loss of interest and use of the bills while in transit.
During the past six months a series of diseases and deaths have been recorded as being caused by the handling of filthy money. The stimulus for such an increase in the reports of these diseases can easily be traced to abstracts of Morrison's pamphlet appearing in the newspapers and magazines. In the New York Evening World, November 8, 1907, there was a report of the death of Edward H. Hall, from "myxœdema," caused by moistening his thumbs on his lips when counting money. Since myxœdema is not considered an infectious disease, this case has no value. The Bridgeport Standard was quoted in a local paper on February 25, 1908, concerning the death of John M. Hopkirk, manager of the Mills Hotel No. 2, in New York, who died from scarlatina, contracted, his physicians believe, through the handling of the dirty bills coming from the slums of the city. Personal contact with these poor people who have little or no medical attention and among whom disease often appears in mild and unrecognized forms, ​seems to have been overlooked as the most probable means of transmission in this case.
"Germs on Money, Harmless—Dr. Doty rejects a popular theory as to source of infection" says the New York Times of February 23, 1908. Dr. A. H. Doty is the health officer of the port, New York. I inquired of him whether he had been correctly quoted in that article and he replied that it practically expressed his views; in fact, he gave me a detailed account of his views which were given in his original article appearing in the New York Tribune on November 11, 1907, under the headlines, "No Disease on Money—Foolish to Consider It as a Medium of Transmission." Dr. Doty writes: "This heading may be a little misleading as I do not say that it is impossible for money to act as a medium of infection, but that if it does occur, it is only in rare instances, and this question must be settled principally by practical experience."
The United States treasurer, who has given this subject long and careful consideration, is emphatic in his statement that there is not the slightest evidence to show that the employees in his department contract infectious diseases any oftener than others who are not in this line of work. This also applies to bank tellers and clerks. Peculiarly enough, those who claim that they have made a careful study of this question do not seem to understand that persons whose vocation involves the constant handling of money are susceptible to the same outside influences or exposure that others are, and are therefore equally liable to contract infectious diseases in the ordinary way, and that the handling of money does not render them immune to disease.
Dr. Park's statement that he found "paper money to be similar to other paper and rags, and capable of carrying living tubercle and diphtheria bacilli for some days or longer," does not mean that money is a frequent medium for the transmission of infectious diseases.
Dr. Doty has for years made a study of infectious diseases, and especially the medium of their transmission. He has collected reliable statistics from paper manufacturers in this country, and has made a personal investigation of the rag depots of Alexandria, Egypt; yet no evidence has ever been found to show that these rag pickers are more subject to infectious diseases than those not connected with the work. "It is fortunate," he says, "that money constitutes such an unimportant factor in the transmission of disease, as nothing could be more farcical, from a sanitary point of view, than an attempt to disinfect it, although this has been seriously proposed. It is important that those who have given this subject careful investigation should aid in the education of the public, in order that they may have a proper understanding of the matter and not be alarmed by sensational literature on the subject."
I do not claim that my study of twenty-four bills proves ​conclusively that money is not a means for the transmission of infectious diseases, but I do think that the absence of virulent disease germs shows that soiled money is at least not a common means of transmission of disease. In order to obtain any conclusive evidence on this point it would be necessary to make a careful study of hundreds or even a thousand bills from hospitals and private sick rooms, drug stores and various other sources.
Emphasis must be given to the animal inoculations carried out in connection with this study, for in a study of this kind they are much more important than the culture experiments, when we consider the susceptibility of guinea pigs to many of the infectious diseases, especially tuberculosis and diphtheria. There may develop within the animal body other forms which would not be detected in a study of the cultures or smears.
It is no surprise that the theoretical does not agree with the practical side of the subject under discussion. This is often the case, especially when the subject is one which concerns the general public, the majority of whom readily agrees with any one who says that dirty money is a certain means of transmission of infectious diseases. Why shouldn't this be so, when we think of the dirt and odors that accompany some of our paper currency? The bills have been in contact with many hands, not necessarily infected ones, but some that have at least been in contact with sores or sputum. Certainly a black picture could be painted and the possibilities made to appear enormous; yet another view is clearly set forth by a bank teller who said: "If one stops to think, money can't be a very common means of transmission, for if it were there wouldn't be so many of us alive to-day; the escape from sure death of those whose duty calls for the constant handling of money, is certainly not merely due to chance."
One conclusion that may be drawn, after a careful study of the subject, is that "money constitutes an unimportant factor in the transmission of disease." We want and certainly need a more frequent redemption of our soiled and worn bills, yet the facts and evidences at hand do not justify us in alarming the public needlessly by rash statements concerning our currency. Admitting the possibility that money may act as a medium of transmission, certainly the failure of any virulent disease germs to manifest themselves in the foregoing experiments will allow us to feel a bit easier in regard to dirty money.
* ↑ Das Geld, ein Krankheitsvermittler," Monatsblatt f. Offentliche Gesundheitspflege, 1879, No. 2, p. 173.
* ↑ Medical Record, August 27, 1892.
* ↑ "A Bacteriological Study of Soiled Paper Money," Columbus (O.) Medical Journal, Vol. XI., 1892–93, p. 391.
* ↑ "Del Contagio par el papel moneda," Revista Medica de Bogota, Julis, 1904, No. 291, p. 355.
* ↑ Hahnemannian Institute, Philadelphia, Vol. II., No. 4, p. 4, February, 1895.