Saturday, July 6, 2013

Foxing – is it a health hazard?

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
 

2 comments:

  1. Excellent post, and some interesting results.

    Hope you don't mind me sharing this at the StampCollectingBlog's Google+ page.

    -k-

    ReplyDelete
  2. Thanks for this posting!
    Nice & very informative blog.
    Microscopy and Microanalysis publishes original research papers in the fields of microscopy, imaging, and compositional analysis.

    ReplyDelete