Friday, 20 June 2008

Mould and flooded homes

Image from
There have been several incidents of extensive flooding of homes throughout the world over the last few years (UK), USA & Bangladesh.
In this article Prof. H. James Wedner of Washington State University discusses a major problem that follows flooding - mould.
The consequences of mould growth in homes and other buildings have been controversial for some time now, especially in the US where there are many legal arguements ongoing as residents try to establish that 'toxic mold' growing in damp homes has effected their health.

Prof Wedner asserts facts such as all mold is not toxic and that there has never been a case proven were breathing in fungal material in the home (i.e. spores) has been shown to be harmful to human health. Those cases that have been reported are for farm workers inhaling massive quantities of fungal material after encountering agricultural scale dust clouds.
There is no doubt that fungi can produce highly toxic substances (see the toxic metabolite listings here) and will do so in the home environment, especially after flooding. The contentious issue is whether or not enough fungal material could be breathed in as dust in the home environment to cause health problems due to mycotoxicosis - toxins are cleared from our bodies at a steady rate via our livers.

The assertion that toxicity has never been proved is potentially insufficient as little work has been reported in this area. One neglected area is of the effects of chronic cumulative exposure to low levels of mycotoxins - in a damp home this could well be a realistic scenario.

Johns Hopkins Hospital recently released a set of guidelines based on a well researched review entitled 'The medical effects of mold exposure'. One assertion made was

"It is highly unlikely that you could inhale enough mold in your home or office to receive a toxic dose".

While for most cases that is probably true, the review that that assertion is based on claims that mycotoxins

"are not cumulative toxins, having half-lives ranging from hours to days depending on the specific mycotoxin."

Again this is largely true but there are papers that suggest that some mycotoxins and/or their health effects can accumulate in the body - in humans in Asia and humans in USA and in laboratory animals.

The paper referenced in that review clearly states at the bottom of page 125 that studies on cumulative exposure to toxins at a level that might be reached in human exposure have not been done. Considering that exposure might include exposure to multiple toxins which might interract it is worthwhile underlining that the statement made by Johns Hopkins and the review is that it is 'improbable' that there are no health effects arising from breathing in the air in damp homes - and not 'impossible'.

Some health effects of molds in the air are well known - allergies are well established for example and Prof Wedner talks about these at length. There is therefore plenty of reason to ensure homes are kept free of moulds and no person should be compelled to live in a mouldy environment. The debate continues in the scientific media (2006). Other causes of health problems in damp houses are also investigated.

The Aspergillus Website has several useful resources on indoor air quality here.

NOTE: it has been brought to my attention that the paper mentioned above entitled 'The medical effects of mold exposure' has been the centre of much debate centred partly around the criticisms I made above. Several doctors strongly refute several statements in that paper - I have added links to the debate to the top of the original paper.

Friday, 13 June 2008

Warning for all gardeners - man killed by Aspergillus in his compost

Image from
This is a very unusual case of an apparently completely healthy man with a normal immune system (the system in our bodies that fights infection) who accidentaly inhaled a cloud of fungal spores while opening bags of compost. The case was so unusual it has been recorded in detail in the medical journal The Lancet. The article was reported in the UK press here.

The huge number of spores inhaled penetrated deep into his lungs as he breathed them in while he worked. This seems to have completely overwhelmed his bodies normal defences and many of the fungal spores grew quickly. He died within days from invasive aspergillosis.

It must be emphasised that this is a very rare case - the only other similar case I have heard of were of a farmer inhaling a cloud of spores from mouldy grain poorly stored in a silo. Nontheless it is important to highlight the importance of awareness of this risk as gardening is a hugely popular activity across the world - take care to avoid breathing in clouds of spores when disturbing decomposing plant material!

Thursday, 12 June 2008

New standardised allergy testing across europe shows way forward.

Allergy testing is notoriously unreliable from test to test as there can be large differences in the results given by different versions of the same test on the same person. This can be due to differences in the allergen preparations used to test the allergy - one frequently contains more allergen than another as the quantity of allergen present can be very difficult to control

This summary of a presentation to the 27th European Academy of Allergology and Clinical Immunology Congress (EAACI) describes the use of a standard test panel across Europe:

"Inhalant allergens tested as the GA2LEN standard prick-test core panel included Aspergillus, cat, dog, Dermatophagoides pteronyssinus, Dermatophagoides farinae, blatella, hazel, alder, birch, plane, cypress, olive, grass mix, artemisia, ambrosia, alternaria, cladosporium, and parietaria, with further region-specific antigens added. Histamine 1:100 was used as positive control, diluent as a negative control."

Comparisons could now be made between countries whereas before each country would have used different versions of the same test. Interesting results included widespread sensitisation to pet hairs and mites across Europe and unexpected reactions such as southern European people reacting to tree pollen found only in the north of Europe!

Aspergillus was tested for but the results aren't mentioned - regardless standardisation of allergy testing across the whole of Europe can only be a good thing as a more compete picture of allergy is built up over time. Correlating this data with disease such as asthma & sinusitis could give valuable clues about what is causing the illness.

Tuesday, 10 June 2008

Bird feeders - keep them clean

Freddy the Parrot
People who feed wild birds and those who keep birds are warned in this article to ensure:

1. The feeders are kept clean by regular removal of old food, washing and thorough drying of the feeder
2. Food is kept dry

These two steps will prevent food becoming mouldy and poisoning the birds - damp foods will rapidly grow fungi and some of those can easily produce mycotoxins which can be lethal. We have an extensive article on avian (i.e. bird) aspergillosis here.

The areas under the feeders should also be kept very clean and clear of fallen seed which can quickly go mouldy and cause respiratory problems for the birds and the people involved. In severe cases (e.g. immunocompromised people, fungal asthmatics, ABPA) this is especially important to such an extent that they should avoid going near the bird feeders altogether.

Good attention to these details will minimise the possibilities of making the birds or their human friends ill.

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