While we are enjoying the summer, it can be a tough time for allergy sufferers. The concentrations of pollen and mold spores in outdoor environment is highest in summer months. Since mold spores and pollen tend to infiltrate into indoor environment their concentration indoors can also be very high in summer. Molds and pollen capable of causing allergic reactions in sensitive individuals are said to be allergenic. Allergy follows inhalation of large amounts of spores or pollen grains. The amounts capable of triggering allergy depends on the specific allergen and the sensitivity of the individual.


Types Of Mold Allergy
Molds as causative agents of respiratory allergy and asthma have been known since the 18th century. Allergic reactions to molds may be either immediate, developing within minutes of exposure (Type I), or delayed, occurring 4 - 8 h later (Type 111). Two of the most important allergenic molds are Alternaria alternata and Cladosporium herbarum. Concentration of these two molds are usually highest outdoors from June to October.


Fungi produce huge amounts of spores. In his book, "The Fifth Kingdom", Dr. Bryce Kendrick, gives the following examples:

• One specimen of the common bracket fungus discharges 30,000,000,000 spores per day every day from beginning of May to the end of September


• A 2.5 cm diameter colony of the green mold, Penicillium, can produce 400,000,000 spores.

Fortunately, these huge numbers are diluted by air and we inhale far much less spore concentrations.

Allergenic Pollen
Among the well known allergenic pollen is the ragweed pollen. Individuals sensitive to ragweed pollen are also sensitive to other pollen grains such as those of poverty weed and false ragweed. Concentrations of these pollens are highest within the months of June to September depending on the flowering time of the particular weed.

When to call a professional mold removal company

Although it's tempting to remove any mold you see, it's not always practical or safe to remove it yourself. Removing mold before you know whether it's toxic can make your family feel ill. And sometimes there's simply too much mold for you to remove safely yourself.

What mold guidelines say

You may clean small areas of mold (less than 1 square meter or 3 square feet) yourself. If you do choose to clean small areas of mold yourself, please follow mold guidelines for your safety and that of your family.

Mold growth covering an area less than 10 square feet is categorised as level 1 mold growth. Level 1 mold growth can be one single area of mold or it can include several patches of mold which together would be less than 10 square feet. Remember! Cleaning the mold without fixing the moisture problem, doesn't solve the mold problem.

If visible mold growth in your house covers more than 10 square feet or if you are not sure how to clean the mold safely, it is recommended you seek professional advice. Cleaning large areas of mold growth releases high concentrations of mold spores into the air, which could make your family feel sick.

Therefore, extensive areas of mold growth should be cleaned by a professional. Heavy concentrations of mold spores can cause or worsen health problems.

Molds don't have to be toxic to cause health problems. Even a common, usually harmless mold can be a health issue if there is a lot of it. However, always consult a professional if your house mold is a toxigenic mold, or if you even suspect a toxigenic mold.

How Do You Tell If A Mold is Toxigenic?

If you need to know whether your house mold is toxic or not, you may want to send a sample to our lab for testing. To send a sample, download the Order Form, complete it and send it together with your samples.

Remember! - please call a mold remediation professional when:

• You the area covered by mold growth is greater than 10 square feet
• You're not sure of the extent of your mold problem
• Mold comes back after repeated cleaning
• The home is very damp
• A family member suffers from allergies or asthma
• You think the mold may be a toxic mold because a family member is suffering from unexplained symptoms that may be related to exposure to toxic mold

If you need a professional mold removal company, please visit this mold remediation professionals directory for a comprehensive list of mold remediation specialists listed by province. We also work closely with some mold removal companies and we may be able to direct you to the right people. Give us a call at 905-290-9101.

Why selecting the right type of agar media is critical

There are several types of agar media used in a microbiology laboratory for culturing molds. These media may differ in their water activity, pH, nutrient content or composition. Molds differ in their growth requirements. Therefore, no single medium is suitable for each and every mold out there.

How would one select the media to use then?

It is easy to select the media to use if one is looking for a specific type of mold. However, in most mold investigation projects, one is interested in knowing the the kinds of viable molds present in the air and their concentrations. The problem of using a single type of media is that some molds may not grow well (or may not grow at all) in the selected media. Hence, although such molds may be the dominant contaminants in the air, they may end up being missed or underestimated. The solution, therefore, is to use more than one type of media or select one that is known to support a wide range of environmental molds. A good example is Malt Extract Agar (MEA). The problem with this media is that it also supports the growth of bacteria. If the environment sampled is contaminated with bacteria, the bacteria grow faster than molds and interfere with mold growth. This problem can be overcome by incorporating a suitable antibiotic or other suitable compounds (e.g., Rose Bengal) into MEA to suppress bacterial growth. Rose Bengal not only suppresses the growth of bacteria but also restricts the spread of fast growing molds thus making it easy for colony counting.

What about culturing of bulk samples?

The same applies to culturing of bulk samples such as pieces of building material or dust. Direct culturing of such material in a single type of media could give erroneous results. If a single media is to be used to culture these types of samples, it is recommended that a lab performs a direct microscopic examination of the samples before culturing. Direct microscopy allows identification of the dominant contaminant (at least to genus level) regardless of whether the mold is dead or cannot grow on media used.

Demonstrating the effect of media on mold growth

To demonstrate how results from a single media can be misleading, examine the 4 petridishes. Two bulk samples were cultured onto 2 different media (DG18 and MEA) after serial dilution. Sample 1 was cultured in petridishes marked “A”. Direct micrsocopic examination of sample 1, indicated it had Stachybotrys as the dominant mold and some slight growth of Penicillium. After incubation, Stachybotrys did not show up at all in DG18 but both Stachybotrys (cream colonies with dark centres) and Penicillium (blue colonies) appeared on MEA. The second sample had Stachybotrys only. After plating onto DG18 and MEA and incubation (see petridishes marked "B"), Stachybotrys appeared on MEA and but not on DG18. These observations clearly indicate how wrong conclusions can be made if the right type of media is not used either in air sampling or culturing of bulk samples.

References

Microorganisms in home and indoor work environments: diversity, health impacts, investigation and control. Flanning Brian, Samson, Robert A., and Miller, David J (Ed.), Taylor and Francis, 2001.

For more information on sampling media,
please visit http://www.moldbacteria.com/prices.html or
call 905-290-101.

Mold Allergy, Mycotoxins And Mold Infections

How Do Moulds Affect Our Health?

There are three ways in which mold can affect our health. These include allergy, mycotoxin poisoning and infections.

• Allergenic Reactions

  An allergy is an acquired sensitivity to allergenic particles such as mold spores and pollen. Allergy acquired from a single exposure is specific to one or to closely related species. Multiple exposures may result in multiple sensitivities. Alternaria and Cladosporium are the two most common causes of allergy. Some mold allergies are associated with work environment such as:
  
  
  
  • farmer's lung (thermophilic actinomycetes, Aspergillus flavus, Aspergillus versicolor, and Eurotium rubrum),
  • cheesewasher's lung (Penicillium casei),
  • malt-worker's lung (Aspergillus clavatus, Aspergillus fumigatus),
  • maple-bark stripper's lung (Cryptostroma corticale),
  • sawmill worker's lung (Rhizopus rhizopodiformis, Penicillium spp., Aspergillus fumigatus, Trichoderma viride),
  • mushroom picker's lung (Pleurotus ostreatus, Pholiota nameko, Aspergillus fumigatus, Doratomyces stemonitis).
  
  

• Mycotoxins

Mycotoxins are toxic compounds that some molds produce. These can be introduced into our bodies through inhalation of spores or airborne mycotoxins in dust. However, eating food contaminated with mold is the major route of mycotoxin poisoning. The best known mycotoxins are aflatoxins produced by various species of Aspergillus. Aflatoxins have a history of causing death in animals and humans and also trigger cancer development.

• Infections

  Infections by common indoor molds is unlikely. However, individuals with weak immune system are at risk of being infected by species of Aspergillus (e.g., Aspergillus fumigatus), Fusarium (e.g., Fusarium solani) and other opportunistic pathogens.

References

Hawksworth, D L, Kirk, P M, Sutton, B C & Pegler, D N (1995). Ainsworth and Bisby's Dictionary of the Fungi. 8th Edition. International Mycological Institute.

Samson, R A., Reenen-Hoekstra, E S., & Frisvad, J C (2004). Introduction to Food-Borne Fungi. 7th Edition. Centraalbureau voor Schimmelcultures, Baarn.

Mould growth only occurs in moisture-damaged and damp building materials. The main causes of mould growth in buildings, therefore, may include poor maintenance and lifestyles of occupants, defective construction and use of building materials susceptible to mould attack. It is estimated that up to 40% and 30% of buildings in the USA and Canada respectively have mould problems.

Health Effects Associated With Mould Growth And Dampness

Several studies suggest that people living and working in damp or mouldy buildings have a higher risk of respiratory health problems such as asthma and bronchitis. Other symptoms associated with mould growth and dampness include blocked nose, itching eyes, and skin irritation. In agricultural environments, where the concentration of spores is several magnitudes higher than in indoor air, inhalation of spores has been associated with cancer, premature birth and farmers lung disease.

The MBL mold training course was first offered in 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!

The 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 Golder Associates Limited. It is has been approved by a number of reputable organization for continuous education. These organizations include:

• American Board of Industrial Hygiene (ABIH)
• Canadian Registration Board of Occupational Hygienists (CRBOH)
• The Institute of Inspection, Cleaning and Restoration Certification (IICRC)
• The National Association of Certified Home Inspectors (NACHI) and
• The Registered Insurance Brokers of Ontario (RIBO).

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

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.

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.

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.

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.