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A preliminary bacterial study of Egyptian paper money

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Abstract

The objective of this study was to investigate the extent of contamination of some of the most used paper denominations of the Egyptian currency (25 PT). Sixty-nine bills in circulation were collected from November 2003 through January 2004. A swab from each bill was cultured on nutrient agar and incubated at 37 degrees C for 48 h. Results showed that over 65% of these bills had a bacterial count above 5.0 cm2. A preliminary identification of organisms present on these paper notes was done using selected Petri dishes with well-defined colonies.
TECHINICAL NOTE
A preliminary bacterial study of Egyptian paper money
FARIDA M. S. EL-DIN EL-DARS & WAEL M. H. HASSAN
Chemistry Department, Faculty of Science, Helwan University, Ain Helwan, Cairo, Egypt
Abstract
The objective of this study was to investigate the extent of contamination of some of the most used paper
denominations of the Egyptian currency (25 PT). Sixty-nine bills in circulation were collected from
November 2003 through January 2004. A swab from each bill was cultured on nutrient agar and
incubated at 378C for 48 h. Results showed that over 65% of these bills had a bacterial count above
5.0 cm
2
. A preliminary identification of organisms present on these paper notes was done using selected
Petri dishes with well-defined colonies.
Keywords: Egyptian paper money, bacterial contamination, Staphylococcus aureus,Staphylococcus
albus,Klebsiella pneumoniae
Introduction
Paper currency is exchanged for goods and services worldwide (Pope et al. 2002). Even
though these bills are made of a rugged mix of 75% cotton and 25% linen (Gadsby 1998),
they offer more surface area for bacteria and microorganisms to reside on both sides. Coins,
on the other hand, offer less residing time for microorganisms and bacteria on their faces
(estimated at 9 11 days) (Bonifazi 2002; Craig 2002). Moreover, the presence of an
appreciable amount of Cu coined metal alloys seems to be the limiting factor for bacterial
survival on coins in general (Bonifazi 2002). On the other hand, the older the paper notes
become, the more space they offer for germs and microorganisms (pathogenic and non-
pathogenic) to accumulate (Brown 2003). Accordingly, this increases the amount of bacteria
circulated and distributed among its handlers.
In a recent study, 94% of 68 US one-dollar bills were found to be contaminated with
potentially pathogenic or pathogenic microorganisms (Pope et al. 2002). Studies on Chinese
currency (China) after the outbreak of SARS in Asia found some banknotes carried over one
hundred thousand types of bacteria and 9500 E. coli-like organisms (Brown 2003). Newer
banknotes from the Hong Kong area carried a lower count than in those in China; however,
banknotes from Northern Korea were almost bacteria free. Older notes studied in China,
Hong Kong, India, Pakistan, Cambodia and the Philippines carried overwhelming amount of
bacteria on both surfaces. Some of these organisms found were considered potentially
Correspondence: Farida M. S. El-Din El-Dars, 3 Kabool Street, Madinet Nasr, Cairo 11371, Egypt. E-mail: fkeldars@hotmail.com
or fkeldars@aucegypt.edu
International Journal of Environmental Health Research
June 2005; 15(3): 235 – 239
ISSN 0960-3123 print/ISSN 1369-1619 online ª2005 Taylor & Francis Group Ltd
DOI: 10.1080/09603120500105976
dangerous to healthy humans and may infect the body through scratches on the hands or
when the hand touches the mouth or nose (Siddique 2003).
In Egypt, certain paper bill denominations have become more used than others in recent
years. One of these denominations is the quarter of a pound or the 25-piaster (PT) paper bill.
This bill represents the minimal change handled for services such as in public transportation,
phone calls and buying newspapers or bread. Also, it may be given to street handlers and
beggars. Therefore, it has precedence in circulation over the 5 and 10 PT coins or bills, two
denominations that significantly lost their true value after the global surge in prices. Thus, the
objective of this study is to investigate the status of contamination of some of the circulated 25
PT paper denominations during the early part of 2004.
Materials and methods
Materials
An equivalent of 17.5 LE worth of twenty-five PT paper bills were collected randomly from a
number of services during the period November 2003 January 2004. The bills were sorted
according to date of mint, grouped and each bill was preserved in sterile plastic file-bags in
order to avoid further contamination. Bacterial examination was carried out at the Biology
Department at the American University in Cairo during April 2004. Other denomination
notes (100, 50, 10, 5 and 1 LE) were also collected during the examination date from
university students and staff and were examined.
Methods
In a sterile chamber, individual paper bills were first introduced. The surface of each bill was
wiped using a sterile cotton swab pre-dipped in sterile distilled water. The swab was cultured
on a sterile nutrient agar in a 5-cm
2
petri dish; one petri dish was used for each individual
paper bill. Each dish was coded according to the order of work and a photo was taken of both
dish and paper bill before incubation at 378C for 48 h. After 48 h, the dishes were transferred
to a fridge for 72 h. A bacterial count was conducted thereafter and newer photos were
recorded for each dish accordingly. For the general identification of microorganisms
contaminating these 25 paper bills, 12 cultured dishes with well-defined colonies covering the
three-mint years span were selected for this undertaking.
Results
Table I provides the bacterial count obtained during examination of the coded petri dishes
according to mint date (2001, 2002 and 2003, respectively). Bills dated in 2001 represented
58% of the collected sample in circulation followed by those from 2002 (33%) and then by
those from 2003 (9%). For the year 2001, 65% of the paper bills had bacterial colony counts
ranging between 5.0 – 11.1 cm
2
. This percentage increased for the 2002 and 2003 bills to
69% and 100%, respectively. There was one case where no infection detected on a sample
dating from 2001. Bacterial count for other denominations is shown in Table II. The data
reveals that the 1, 5 and 50 LE banknotes (all minted in 2002) had a bacterial count of
10 cm
2
, which was equivalent to the 25 PT bills. The 10 and 100 LE bills had average counts
of 5.5 and 4.3 cm
2
, respectively. Table III shows the types of organisms isolated from the
selected 12 cultured petri dishes and the number of isolates. From these results, three types of
microorganisms were identified, namely: Staphylococcus aureus, Staphylococcus albus and
236 F. M. S. El-Din El-Dars & W. M. H. Hassan
Klebsiella pneumoniae. The more virulent aureus was isolated from 8 dishes; the relatively
harmless albus (S. epidermidis albus) was isolated from 5 dishes and K. pneumoniae was isolated
in 6 of the selected cultured dishes. In addition to the bacteria identified, observations
concerning the cultured petri dishes showed that 38 dishes (55%) developed significant fungal
growth.
Table I. Bacterial colony count on 25 PT paper bills after incubation at 378C for 48 h.
No of bills
Date of mint (mm/yy)
Colony count /cm
2
08/01 & 12/01 01/02 01/03
10.0 – 11.1 4 1 2
9.0 – 9.9 3 4 1
8.0 – 8.9 6 4 0
7.0 – 7.9 1 1 2
6.0 – 6.9 7 3 0
5.0 – 5.9 5 3 1
4.0 – 4.9 3 0 0
3.0 – 3.9 5 3 0
2.0 – 2.9 1 3 0
1.0 – 1.9 3 1 0
0.1 – 0.9 1 0 0
No infection 1 0 0
Total number sampled 26 + 14 = 40 23 6
Table II. Bacterial colony count on a variety of paper bill denominations collected randomly from university students
and staff during April 2004.
Currency denomination Date of mint Colony count/cm
2
100 LE January 2000 4.3
50 LE June 2002 10
10 LE No date 5.5
5 LE December 2002 10
1 LE March 2002 10
Table III. Organisms isolated from 12 cultured Petri dishes.
Organisms Number of isolates
Pathogenic
Staphylococcus aureus 8
Klebsiella pneumoniae 6
Feebly or non-pathogenic
Staphylococcus albus 5
Total isolates 19
Bacterial study of Egyptian paper money 237
Discussion
Until recently, the studies concerning the contamination of paper banknotes and coins have
been few and rather limited (Bonifazi 2002; Pope et al. 2002). However, after the outbreak of
some transmissible diseases such as SARS in Asia, these studies have gained some serious
consideration (Siddique 2003; Brown 2003; Podhajny 2004). The reason behind this is that
money is thought to play a role (direct or indirect) in spreading disease. Both paper banknotes
and coins offer ample surface areas to harbor bacteria and microorganisms. However, due to
the difference between the textures of these paper notes compared to the metal alloys used for
coins, paper notes can accommodate a variety of contaminants and for longer periods
(Gadsby 1998; Brown 2003).
The more the paper bill stays in circulation, the more opportunity there is for it to become
contaminated (Gadsby 1998; Brown 2003). In effect, the wear and tear on these older notes
offers more hiding space for germs to reside. Studies in some Asian countries revealed that
these older notes carry an overwhelming number of bacteria (Brown 2003). The rugged
texture of these paper notes was found to accommodate chemicals as well as germs within
(Gadsby 1998). A study concerning the one US dollar found that drug particles accumulate
by being easily squeezed into the fiber matrix (Gadsby 1998).
In this study, most of the 25 PT paper notes provided positive indications of bacterial
contamination. On the 2001 notes (58% of the total sample), the maximum bacterial count
obtained was 11.1 cm
2
and the minimal was 0.64 cm
2
. Only one note from this year group
showed no signs of infection. Results for the 2002 notes revealed a bacterial count range
between 1.6 cm
2
and 10 cm
2
. However, the crisper notes from 2003 had a comparatively
higher range from 5.0 to 10 cm
2
. The higher bacterial count for the 2001 notes may be
attributed to the fact that they have been in circulation for almost two and a half years and by
appearance, they were already worn out. The 1, 5 and 50 LE notes had similar maximum
bacterial counts of 10 cm
2
followed by the 10 LE (5.5 cm
2
) and the 100 LE (4.3 cm
2
). This
may be an indication that the first group of currency denominations may be more frequently
used as they represent the other common paper denominations exchanged when using a 100
LE bill. It could mean that smaller change may be required to render or receive more services.
The Egyptian currency denominations showed similar bacterial counts comparable to those
reported for some US currency denominations. In 2000, it was reported that the one-dollar
bill had an 8.2 cm
2
bacterial count, the five dollar 7.9 cm
2
, the ten dollar 5.8 cm
2
and, finally,
the twenty-dollar bill 5.4 cm
2
(Chase 2000).
Concerning the general identification of microorganisms contaminating these 25 paper
bills, the three types of microorganisms identified (namely: Staphylococcus aureus,
Staphylococcus albus and Klebsiella pneumoniae), were similar with those identified on US
one-dollar bills (Gadsby 1998; Leutwyler 2001; Bonifazi 2002; Pope et al. 2002). The more
virulent aureus is a potential pathogen present on hands, normal skin, nasal cavities and
suppurative lesions of man (Wilson & Miles 1957) as well as on the skin of people suffering
from eczema (Gadsby 1998). This organism can survive outside a living host for prolonged
periods (Pope et al. 2002). The relatively harmless albus (Staphylococcus epidermidis albus)is
feebly pathogenic or non-pathogenic organism present on skin, in the hair and in abscesses
after suturing of operation wounds as well as in the air, water and dust (Wilson & Miles 1957).
Pneumoniae is another virulent organism that is isolated from the respiratory tract of man and
animal (Wilson & Miles 1957). It causes both community and hospital acquired infections
(Pope et al. 2002).
In conclusion, this study helped to quantify the extent of contamination of one of the most
circulated banknote denominations used in Egypt. At this point, the only recommendation to
238 F. M. S. El-Din El-Dars & W. M. H. Hassan
be set forth is for individuals to improve upon their personal hygiene by always washing hands
to limit infection. Also, before recommending any regulatory measures, further work is
required to provide a complete picture about the extent of contamination of other
denominations in circulation as well as coins used.
Acknowledgments
The authors would like to acknowledge the valuable assistance received from Prof. Andrew J.
Main, Chairman of the Biology Department, the American University in Cairo as well as that
of Mrs. Hanan El-Kassas, for facilitating the undertaking of the experimental part of this work
at the student research laboratory.The authors would also like to acknowledge the valuable
assistance received from Dr Laila M. Asker, MD, during the process of write-up as well as her
enlightening discussions and explanations on bacteria and other microorganisms.
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Bacterial study of Egyptian paper money 239
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... For instance, food vendors often times handle money while they serve food at the same time to their customers. Previous works by FSA [24] and El-Dars and Hassan[22] suggests that simultaneous handling of food and money contributes and may as well cause sporadic food borne-diseases. ...
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Money's dirty, but health risks overstated'. Natural Foods Merchandiser XXIII(3):36. Available
  • Wl Bonifazi
Bonifazi WL. 2002. 'Money's dirty, but health risks overstated'. Natural Foods Merchandiser XXIII(3):36. Available: http://www.naturalfoodsmerchandiser.com.
How dirty is your money? CNN International
  • A Brown
Brown A. 2003. 'How dirty is your money?' CNN International. Available: http://edition.cnn.com/2003/WORLD/ asiapcf/
Dirty money: Amount of bacteria on different
  • R Chase
Chase R. 2000. 'Dirty money: Amount of bacteria on different denominations of money'. Available: http:// www.ga.k12.pa.us/academics/ms.
How dirty is your money? Dave Summer International
  • S Craig
Craig S. 2002. 'How dirty is your money?' Dave Summer International. Available: http://www.summers1.freeseve.-co.uk
Filthy lucre - money is contaminated with bacteria - including related article on money taken from magazine editors
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Gadsby P. 1998. 'Filthy lucre -money is contaminated with bacteria -including related article on money taken from magazine editors'. Available: http://www.findarticels.com.
Estimating the dollar's bacterial exchange rate
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How dirty is your money?' Paper Film & Foil Converters (PFFC) Available
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Podhajny RM. 2004. 'How dirty is your money?' Paper Film & Foil Converters (PFFC). Available: http://pffconline.com/
Dirty money: You're carrying more than cash in your wallet Philippine Headline News Online
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Siddique S. 2003. 'Dirty money: You're carrying more than cash in your wallet'. Philippine Headline News Online. Available: http://www.newsflash.org/2003/.