Introduction
For
many years philatelists the world over have ‘felt’ that foxed
stamps should be kept away from the rest of their collections. Many
suspected that foxing and toning could spread just like an
infectious disease, from one stamp to another.
Almost
all stamp dealers and a lot of collectors regularly find themselves
sorting and coming into close contact with old collections, which may
be riddled with foxed/toned stamps and albums. The mouldy smell that
these emanate is a sure sign that a fungal infection is rife. But is
it just a bad smell or is it something much more sinister?
A preliminary investigation using a Scanning Electron
Microscope by Dr. Patrick Trimby (SEM
section manager at the Australian Centre for Microscopy &
Microanalysis (ACMM) at the University of Sydney)
on two samples provided by the author has confirmed previous studies,
carried out on foxing of archived paper, that one of the main
culprits of foxing in paper and paper-like items, like stamps, is a
fungal infection.
SEM
results
The
Australian Centre for Microscopy & Microanalysis (ACMM) at the
University of Sydney is the largest and most comprehensive facility
of its type in Australia and is the headquarters of the Australian
Microscopy & Microanalysis Research Facility (AMMRF), a national
grid of equipment, instrumentation and expertise in microscopy,
microanalysis, electron and X-ray diffraction. Researchers at the
ACMM have access to an outstanding array of imaging and analysis
equipment, supported by over 40 dedicated research, administrative
and technical staff.
Dr
Trimby performed a preliminary analysis of the two samples supplied
by the author. Sections
were taken from the edges of the 2 stamps (red arrows), away from
the printed region, so as to ensure that like was being compared with
like. (see fig. 1)
Each
sectioned sample was coated with a thin layer of metallic gold (this
is a necessary step for the reflection/refraction of the electron
beam) and then were imaged, using a standard SEM.
Dr
Trimby reported that the results showed 2 clear differences between
the foxed and not-foxed areas on the stamps (see fig. 2).
1.
The foxed areas have a relatively high abundance of fungi. In the
attached images the fungal hyphae (thin tendrils) are clearly
visible, as well as a number of conidiospores (fungal spores).
However, he did not find any evidence for fungi in the not-foxed
sample, just some small crystalline fragments on the surface.
2.
The foxed sample had a much more porous paper structure with the
cellulose fibres clearly exposed much more so than in the not-toned
sample. This would suggest that either the stamps have been
manufactured from different paper batches with different quality
(unlikely for this issue), or more likely, that a filler or some
fibres have been etched away
over time (maybe as a result of paper acidity or as a result of
fungal activity or both), leaving lower fibres exposed to continued
attack.
Brief
History
The
first instance of foxing was reported 1848, it is believed that it
was named after the rusty colour of ‘Reynard the Fox’.
Surprisingly, research into the causes and the prevention of foxing
has been scarce, especially in relation to philatelic material. This
is surprising for two reasons: first; stamp collecting
has for many years been the most popular of hobbies and second;
stamps are among the most valuable (in terms of prices at auctions)
items on the planet.
The
problem of foxing in archived paper has been investigated off and on
for about sixty years, most researches seem to agree that, although
the onset of foxing maybe caused by a number of factors, either
acting singly or in concert, all will eventually involve some form of
fungal infection.
Fungi
It
has been estimated that there are around 1.5 million species of
fungi, with about 5% of these having been formally classified. About
100 species have been recognised as having the ability and/or the
inclination to ‘digest’ cellulose and cellulose containing
materials like paper.
A
number of researches have been successful in producing fungal
cultures from swabs of foxed areas and have identified a number of
species of the fungi involved, some of these are shown in Table 1
Aflatoxins
Aflatoxins
are among the most carcinogenic substances known. Aflatoxins belong
to a class of compounds known as mycotoxins. Over
300 mycotoxins are known and all they are produced by several species
of fungi. Most of the mycotoxins of concern are produced by three
genera: Aspergillus,
Penicillium,
and Fusarium.
Aspergillus
flavus
and Aspergillus
parasiticus
have received most of the attention as they infect our main food
sources: cereal grains, potatoes, fruits and nuts.
The term aflatoxin is actually derived from the abbreviation for
Aspergillus
flavus: A. flav.
In
the 1960 more than 100,000 young turkeys on poultry farms in England
died in the course of a few months from an apparently new disease
that was termed "Turkey
X disease"
Research showed that the disease was associated with the animals’
feed: a mouldy peanut meal imported from Brazil.
At
the time, little was known about Aflatoxins, but some scientists
suspected that they would be linked to liver cancer in humans. Soon
after the U.K. outbreak, a young MIT toxicologist named Gerald Wogan
launched a thorough, decades-long investigation into the toxins,
eventually exposing them as the most potent carcinogens humans can
encounter.
Epidemiological
studies carried out in Thailand in the late 1960’s during a period
of 5 years showed that there is a high correlation between the
ingestion of mouldy food and the occurrence of lever cancers.
Burg
et. al. after an extensive study of airborne Aflatoxins produced
during the handling of contaminated corn, concluded that the
concentration of Aflatoxins in the lungs may actually be higher and
more potentially dangerous when breathing contaminated air than the
concentration of the same toxins in the stomach after eating mouldy
food e.g. peanuts.
Researches
at Cornwell University’s Dept of Animal Science have warned that:
“Safety is a key issue for scientists working in the aflatoxin
area. Steps must be taken to minimize exposure to the toxins as well
as to the producing microorganisms, Aspergillus
flavus
and Aspergillus
parasiticus.”
Chronic, or continued
exposure may lead to a high risk of developing liver cancer, as
aflatoxin metabolites can cause mutations known to cause liver
tumors.
Children, are particularly affected by aflatoxin exposure
which leads to stunted growth and delayed development. The
International Agency for Research on Cancer (IARC) has designated
aflatoxin as a human liver carcinogen.
Conclusion
You
will have no doubt noticed from Table 1 that Aspergillus
flavus, the
organism that produces the most toxic aflatoxin known, Aflatoxin B1,
was identified in connection with foxing of paper.
The
SEM pictures shown above are not sufficient evidence to identify the
actual species of the fungus, but an expert mycologist wrote, after viewing the SEM photos above, in an email to Dr Trimby that from
the appearance of the spores the fungus in the electron micrographs
could possibly be an Aspergillus.
Are
these organisms associated with foxing in stamps? Do they pose a
threat to the long term health of collectors and dealers? Can toning
be prevented, cured, stopped? Should toned stamps and other toned
philatelic items be permanently sealed or even burned?
All
these are important question to our hobby and further work is not
only vital to the health of our little printed friends but also to
our own health.
Consider
how many collectors and dealers are world-wide and how many of these
live in tropical and semitropical environments – conditions ideal
for fungal growth. Consider how many times you have de-papered stamps
that may have been infected (just like in food stuffs, browning
occurs in the later stages of fungal attack, perfect- looking items
may in fact be riddled with the fungus). Consider how many times you
have handled and inhaled the fetid air from old collections. Consider
the two major up-and-coming stamp regions: China and India; both
densely populated; both with tropical and sub-tropical regions and
both with increasing numbers of enthusiastic collectors.
This
preliminary study, described at the beginning of this article, was
done with no funding and was completely due to the author’s
interest and the generosity of Dr. Trimby and of his Department.
Essential further work will require funding from interested
parties…and that could include you, if you are reading this
article.
End
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