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A Mold Training Course With A Difference

The MBL mold training course was first offered on July 5, 2005. Readers of our newsletter suggested that we provide some training based on the topics we used to discuss in our newsletters. That is how this course was born. Since then we have offered the course at least once every month!

Mold training course manual and CDThe mold training course started as a half-day course covering topics such as:

  • How to recognize indoor mould. This section of the course was initially designed for beginners but even experienced professionals have found it useful. Sometimes, one can’t tell for sure whether they are dealing with mold or not.
  • How to develop effective sampling strategies. Whether to sample for mold or not (like many other issues involving mold) is controversial. However, there are instances where sampling can’t be avoided. Collection of the right kind of samples and at the right place can make results interpretation easier.
  • How to interpret laboratory results. With no standards on permissible exposure levels, opinions on lab results can significantly differ. An understanding of the key limitations of lab results and the principles applied on results interpretation is essential.

A number of participants suggested that we increase the course content to make it a one-day course. We added more material to the original sections and also added a section on mold control.

The mold training course is currently offered by MBL in association with leaders in the industry. It is has been approved by a number of reputable organization for continuous education. These organizations include:

For more details about the course click http://www.moldbacteria.com/training.html

Book today using the booking calendar below.

[booking type=6 form_type=’standard’ nummonths=2]

Penicillium Species As Indoor Air Contaminants

In 1928, Alexander Fleming’s bacterial cultures were contaminated by airborne spores of a green mould. Fleming noticed that bacteria were not growing close to the green mould. He concluded that the mould was producing a compound that was killing or inhibiting the growth of bacteria. That is how Penicillins, the oldest and probably the best known of all the antibiotics were accidentally discovered. The green mould was later identified as Penicillium notatum. Penicillium notatum (now called Penicillium chrysogenum) is one of the most common indoor fungal contaminants.Spores of Penicillium chrysogenum

Penicillium is found worldwide. The spores of this mould are found everywhere in the air and soil. In indoor environment, this mould proliferates in damp conditions. Penicillium is commonly called the blue or green mould because (depending on the species) it produces enormous quantities of greenish, bluish or yellowish spores which give it the characteristic colour. The blue in the blue-cheese, for example, is the colour of the spores of the Penicillium species used in ripening the cheese. About 200 species have been described.

Penicillium species as contaminants of indoor air

In indoor environments, Penicillium is extremely common on damp building materials, walls and wallpaper, floor, carpet mattress and upholstered furniture dust. The spores of this mould are produced in dry chains and are exposed to the air hence their ease to become airborne. Spore sizes range from 3 to 5 micrometres. Because of their small size, they take long to settle and can be inhaled deep into the lungs. The spores are found indoors throughout the year. For air samples analysed by direct microscopy, it is hard to distinguish between spores of Penicillium from those of Aspergillus. Therefore these spores are often reported as Aspergillus/Penicillium. The most common Penicillium species in indoor environment is Penicillium chrysogenum. It produces a number of toxins of moderate toxicity. It is also allergenic and can infect immuno-compromised patients.
Picture of Penicillium chrysogenum on wood

Penicillium species as a health hazard

Many species of Penicillium are common contaminants on various organic materials and are recognized potential mycotoxin producers. The most well known toxin producing species in foods include P. citreonigrum, P. citrinum, P. crustosum, P. islandicum and P. verrucosum. Therefore, when it comes to food contamination, correct identification of Penicillium is important. Although, human pathogenic species are rare, opportunistic infections have been reported in individuals with weakened immune system such as the HIV/AIDS patients. The species commonly associated with opportunistic infections is P. marneffei.

Penicillium species as food spoilage organisms

Penicillium species are common causes of spoilage of fruits, cheese, cold meats, old sandwiches, cereals and cereal products and a host of other agricultural and animal products. For example, Penicillium italicum and Penicillium digitatum are common causes of rot of citrus fruits, while Penicillium expansum is known to spoil apples. As mentioned above, most Penicillium species produce toxins. It is a good practice to discard foods with any visible mould growth. It is important to know some species of Penicillium are beneficial to humans. For example, cheeses such as Roquefort, Camembert and others are ripened with species of Penicillium.Penicillium on food

References

  1. Introduction to food and airborne fungi. Seventh Edition. Samson, Robert A., Hoekstra, Ellen S., Frisvad, Jens C (Editors). Centraalbureau voor Schimmelcultures, 2004.
  2. Microorganisms in home and indoor work environments: Diversity, Health Impacts, Investigation and control. Flanning Brian, Samson, Robert A., and Miller, David J (Ed.), Tayler and Francis, 2001.

For more information on Penicillium species,please visit http://www.moldbacteria.com/learnmore/moldlist.html or call 905-290-101.

Chaetomium species as indoor contaminants

Chaetomium species

Chaetomium globosumChaetomium species are found worldwide in soil, dung, or decaying plants. Most species are prolific producers of the enzyme cellulase that breaks down cellulose. Destruction of paper and other materials containing cellulose (including foods, feeds, paper, textile, bird feathers, seeds and military equipment) by species of this mould is well documented. Due to their strong ability to destroy material, Chaetomium species are often used in testing materials for resistance to mould growth.

Chaetomium is perhaps the third most common indoor fungal contaminant of mouldy damp buildings. It may be found on wet drywall, wall-paper, carpets, window frames, baseboards and plywood. The most widespread and common species is Chaetomium globosum. This species causes many problems of biodeterioration of paper and other cellulose containing material. It is considered a “weed” of mushroom beds, where it inhibits the growth of cultivated mushrooms.

Chaetomium as a contaminant of indoor air

Generally the concentration of airborne Chaetomium spores is very low. This is because the spores (= ascospores) are produced within flask-shaped bodies (= perithecia) and not exposed to air like those of moulds such as Penicillium and Aspergillus. When the spores mature, they are released inside the perithecium and then squeezed out in a column like toothpaste through an opening at the top of the perithecium. The coiled hairs trap the spores such that they are not easily dispersed into the air by wind.Chaetomium globosum spores

The other reason why the concentration of airborne Chaetomium spores is usually low is because the spores are relatively large and hence have relatively high settling rates and therefore do not remain airborne for long. As a result, airborne spore concentration of Chaetomium is usually low even in contaminated buildings. Due to low air concentration, exposure to airborne Chaetomium is insignificant except in situations where the mould has dried out and disturbed.

What does the presence of Chaetomium in a building tell us?
Chaetomium is one of those moulds that require chronic moisture conditions for it to grow. It’s presence is therefore an indication of existing or previous serious moisture problem. A few spores in pre-remediation air samples is an indication of a mould problem in the building. Because of the low airborne concentration, rarely is Chaetomium detected in outdoor samples. Hence any spores detected indoors are highly likely to have a source indoors and not outdoors. One can also sample house dust to determine whether Chaetomium is present or not.

Health Effects

Although Chaetomium species are rarely associated with human infections, there are reports of infections involving individuals with weak immune system. Chaetomium globosum is known to produce 2 toxins in moisture damaged buildings, chaetoglobosins A and C. These toxins have the potential to cause illness to building occupants.

For more information on Chaetomium species,please visit http://www.moldbacteria.com/learnmore/moldlist.html or call 905-290-101.

References

  1. Fogle, Matthew R (2007). Growth and mycotoxin production by Chaetomium globosum. PhD Dissertation, Texas Tech University Health Sciences Center.
  2. Udagawa S, Muroi T, Kurata H, Sekita S, Yoshihira K, Natori S: Chaetomium udagawe: a new producer of sterigmatocystin. Trans Mycol Soc Jap 1979, 20, 475-480.
  3. Domsch KH, Gams W, Anderson T-H: Compendium of Soil Fungi. Academic Press, London 1993.
  4. Arx JA von, Guarro J, Figueras MJ: The Ascomycete Genus Chaetomium. J. Cramer, Berlin 1986.
  5. Barron MA, Sutton DA , Veve R, Guarro J, Rinaldi M, Thompson E, Cagnoni PJ, Moultney K, and Madinger NE, Invasive Mycotic Infections Caused by Chaetomium perlucidum, a New Agent of Cerebral Phaeohyphomycosis. Journal of Clincal Microbiolgy, Nov. 2003, p. 5302–5307 Vol. 41, No. 11
  6. Piecková E: In vitro toxicity of indoor Chaetomium Kunze ex Fr. Ann Agric Environ Med 2003, 10, 9–14.

Non-viable Fungal Air Sampling Alone May Not Be Adequate

Non-viable Air Sampling

 

 

 

VersaTrap air sampling casette Air-O-Cell air sampling casette Allergenco air sampling casette

Indoor air sampling for airborne fungi is frequently conducted to assess the levels of fungal contamination and subsequently the potential risk to building occupants. It is also used to determine if there was hidden mould growth in the building or to determine the effectiveness of remediation procedures. One of the most cited advantages of non-viable air sampling is that detection of fungal structures (spores, hyphal fragments, etc) is not dependent on their viability or the suitability of agar media. Non-viable air samples are collected with samplers such as Air-O-Cell, Allergenco, VersaTrap, Burkard, Cyclex, Cyclex-d and Micro-5 among others. The spores (whether viable or dead) and other particulates are trapped on the sticky surface of the spore trap and can then be directly enumerated and identified under a microscope. Since both viable and nonviable spores can be enumerated, an efficient non-viable air sampler is expected to give a better estimate of the level of airborne fungal contamination than a viable air sampler.

Viable Air Sampling

Picture of Colony Forming Units: CFUViable air samples are often collected on agar media either in strips (if using Reuter Centrifugal Sampler) or in Petri-dishes for Andersen sampler. Unlike non-viable air sampling, detection and subsequent enumeration and identification of airborne fungal particulates collected on growth media depends on whether the spores and hyphal fragments are viable and whether the media used can support their growth into colonies. For this reason, colony counts are usually lower than spore counts. Even if all the fungal structures were viable, colony counts are likely to be lower than the spore/hyphal fragment counts because what is counted as a single colony could have developed from more than a single spore or hyphal fragment. In one study it was found that the ratios between the total fungal spores collected by the Burkard sampler and the viable fungi collected by the Andersen sampler ranged between 0.29 and 7.61.

Non-viable Air Sample

Picture of Chaetomium and Aspergillus/Penicillium sporesIs Non-viable Fungal Air Sampling Alone Adequate? In most cases viable air sampling is only used in situations where identification of the moulds to species level is required. However, our observation in the lab seems to suggest use of spore traps alone may not be adequate for airborne fungal sampling. On many occasions we have recovered moulds in viable samples that were not observed in non-viable samples even when viable and non-viable samples were taken side by side. For example Chaetomium and Stachybotrys spores, which are fairly easy to identify from spore traps have appeared in viable samples, yet, they were not detected from the non-viable samples. We have also observed that although non-viable sampling gives higher counts than viable sampling in most cases, this is not always the case. There are many factors that can contribute to these “unexpected” results.

Conclusion

Picture of Viable Air Samples On RCS Agar StripsSince both non-viable and viable air sampling have limitations, using either method singly is not adequate. To obtain conclusive information on the level of contamination and the diversity of airborne fungi in a building, taking both viable and non-viable air samples is preferable. We recommend the Calgary Health Region’s protocol, “Fungal Air Testing, Investigation and Reporting Requirements for Residential Marihuana Grow Operations (Revised May 2006)”. With few exceptions, the protocol requires that fungal air sampling consist of both viable samples (e.g. RCS or similar) and non-viable samples (e.g., Air-O-Cell) taken side by side.

References

Adhikari A., Sen M.M., Gupta-Bhattacharya S., Chanda S. (2004). Airborne viable, non-viable, and allergenic fungi in a rural agricultural area of India: A 2-year study at five outdoor sampling stations. Science of the Total Environment, 326 (1-3), pp. 123-141.

Calgary Health Region (2006). “Fungal Air Testing, Investigation and Reporting Requirements for Residential Marihuana Grow Operations (Revised May 2006)”.

Canadian Residential Indoor Air Quality Guideline For Moulds

Whenever mould testing is performed people want to know whether the levels of mould detected are harmful or not. While there is enough evidence to suggest exposure to indoor mould result in an increased prevalence of asthma-related symptoms such as chronic wheezing, irritation symptoms, and non-specific symptoms it has proved difficult to set exposure limits for mould. Health Canada has issued a residential indoor air quality guideline for moulds as quoted below:

“Health Canada considers that mould growth in residential buildings may pose a health hazard. Health risks depend on exposure and, for asthma symptoms, on allergic sensitization. However, the large number of mould species and strains growing in buildings and the large inter-individual variability in human response to mould exposure preclude the derivation of exposure limits. Therefore, Health Canada recommends:

  • to control humidity and diligently repair any water damage in residences to prevent mould growth; and
  • to clean thoroughly any visible or concealed mould growing in residential buildings.

These recommendations apply regardless of the mould species found to be growing in the building. “

Any visible mould should be removed safely. There are mould guidelines that outline safe procedures for mould removal. Most of these guidelines are available on the internet.

If you are a homeowner or an occupant of a house and you see visible mould growth, you may want to send samples to a laboratory for testing. The lab report would tell you the types of mould species growing in the house and whether they are known to be of health concern. But remember, regardless of the types of moulds present, the mould has to be cleaned.

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