The most common indoor molds include Cladosporium, Penicillium, and Aspergillus.

The common Aspergillus infections include invasive Aspergillosis, non-invasive Allergic Pulmonary Aspergillosis (ABPA), and Chronic Pulmonary and Aspergilloma (CPA). Depending on the type and severity of aspergillosis, affected individuals suffer from a range of symptoms including wheezing, difficulty in breathing, runny nose, coughing and weight loss. Severe bleeding in lungs and systemic infections are also often seen.

Causes of Aspergillosis

As mentioned earlier, aspergillosis is caused by the fungus Aspergillus. There are about 180 species of Aspergillus but only a few of them are known to cause infections in humans. Aspergillus fumigatus is the most common cause of aspergillosis. Other possible causes of aspergillosis include Aspergillus flavus, Aspergillus terreus, and Aspergillus niger.

Preparing for the holidays can be an exciting time to share with loved ones.

Gathering up old holiday decorations and adding new ones to the collection has been a long standing tradition in many families.

This year however, there are a few precautions we urge people to take when purchasing ornaments and other decorations for mold contamination. The most recent recall of Signature Collection ornaments, picture frames and 43 centimeter red trees were found to contain Aspergillus mold.

Some Aspergillus mold can cause serious disease in humans and animals. Aspergillus fumigatus, Aspergillus flavus and Aspergillus clavatus are the most common to cause either pathogenic or allergenic reactions or both. Pulmonary aspergillosis can also result with symptoms that can range from fever, cough, chest pain or breathlessness. The most at risk group to contract aspergillosis after exposure to Aspergillus mold are those with weakened immune systems or lung disease.

Consumers have been recommended to immediately stop using these products, enclose them in a plastic bag, and return them to the nearest Papyrus or Carlton Cards store, or Schurman Retail Group’s Tennessee Distribution Center for a refund. Fortunately, at present the Schurman Retain Group, the United States Consumer Product Safety Commission (US CPSC) and Health Canada have not received any reports of incidents related to these products.

The recalled products were sold at Papyrus and Carlton stores across Canada and the United States from September 29, 2012 to November 21, 2012; 5,807 items in Canada and 10,450 items in the United States. Manufacturing of the recalled products was done in Pasig City, Philippines by Idianale Inc/Dekokraft. Distribution was through the Schurman Retain Group in Fairfield, California. Quality control during manufacturing, packaging and transportation may need to be assessed to determine where the contamination arose.

For the original article please visit: http://www.thefountainpen.com/s/showstory?id=10364

All laboratory staff at MBL are trained in identifying Aspergillus spp. If you have any concerns that products you have may contain mold, you can send in a sample of it to our lab to gain some peace of mind (either cut a piece of it, take a swab or a tape-lift). We wish you a safe and joyous holiday season. For information about our mold testing or bacteria testing services, please contact Mold & Bacteria Consulting Laboratories. Please call our Ontario, Mississauga Office at 905-290-9101.

Indoor air sampling for mould spores may be conducted to help in evaluating the air quality after occupants’ complaints of ill health, to determine the effectiveness of remediation procedures, to assess health hazards or to proactively monitor indoor air quality.

Mould spores enter a building from outdoors through:

• air intakes for the heating, ventilation, and/or air conditioning system (HVAC),
• doors and windows
• contaminated building materials and contents.

Interpreting Air Sample Results For Mould Spores

Since under normal conditions indoor mould spores originate from outdoors, the common practice in mould investigation is to compare indoor airborne fungal populations and their concentration to those of outdoor samples.

While indoor/outdoor comparison can work fairly well for culturable air samples or non-viable samples with easy to identify fungal spores, it may not work all the time for non-viable air samples when the dominant spore types both indoors and outdoors are Aspergillus/Penicillium, unidentified spores, unidentified basidiospores, or unidentified ascospores.

Comparing Indoor/Outdoor Concentrations of Aspergillus/Penicillium and Unidentified Spores

Spores of Aspergillus and Penicillium are rounded or slightly elongated, and smooth or ornamented depending on the species. Since these spores have no other distinguishing characteristics, laboratories usually lump them together as Aspergillus/Penicillium when they analyze air samples by direct microscopy (total spore counts).

Unfortunately, there are many other fungal genera and species which produce spores that are very similar and difficult to differentiate from those of Aspergillus and Penicillium.

For example, spores of some species belonging to the following groups may easily be misidentified as Aspergillus/Penicillium: Trichoderma, Absidia, Acremonium, Aphanocladium, Beauveria, Chromelosporium, Cladosporium, Phialophora, Gliocladium, Metarrhizium, Monocillium, Mortierella, Mucor, Paecilomyces, Syncephalastrum, Verticillium and many others.

Fortunately most of these are not as common indoors as the Aspergillus and Penicillium species.

Unidentified spores including ascospores and basidiospores also present problems when it comes to indoor/outdoor comparison if these spores are in high concentrations both indoors and outdoors. Trying to compare indoor/outdoor samples for these categories of spores could be erroneous since one could be comparing spores belonging to totally different genera.

The Solution

Presence of significant numbers of Aspergillus/Penicillium and unidentified spores (including ascospores and basidiospores) in the indoor environment is indicative of poor air quality.

However, it’s difficult to tell from these results whether the indoor spores originated from outdoors and whether the spores belong to Aspergillus/Penicillium or other moulds with similar spores. The solution to this problem would be to collect culturable air samples.

Culturable air samples could help in characterizing most of these moulds if they grow and produce spores in culture.

References

1. Brian G. Shelton, Kimberly H. Kirkland, W. Dana Flanders, and George K. Morris (2002). Profiles of Airborne Fungi in Buildings and Outdoor Environments in the United States. Appl Environ Microbiology; 68(4): 1743–1753
2. Smith, E. Grant (2000). Sampling and Identifying Allergenic Pollens and Molds, Blewstone Press, San Antonio, Texas.

The general public thinks that black indoor molds are toxigenic because of the publicity that Stachybotrys chartarum (a.k.a Stachybotrys atra in the old literature), a black mold, received in the recent years. However, the colour of the indoor molds does not determine whether they are toxigenic or not.

Growth of indoor molds on building materials is determined by the water activity (a_w) among other factors. The a_w is a measure of the moistness of the material. Some indoor molds are capable of growing over a wide range of a_w but there is always an optimal range.

Common Indoor Molds

The indoor molds commonly found on building materials are discussed below.

Stachybotrys chartarum

Stachybotrys chartarum is cosmopolitan and grows naturally on straw and other cellulose containing materials in soil. In the indoor environment, this mold is commonly found together with Stachybotrys chlorohalonata on cellulose containing materials including paper, canvas and jute which are wetted to a water activity > 0.98.

In a study on indoor molds conducted in Denmark, Stachybotrys chartarum was found to produce a number of mycotoxins including macrocyclic trichothecenes, satratoxins and roridins when growing on building materials. However, only 35% of the isolates from buildings produced the extremely cytotoxic mycotoxins, the satratoxins.

This led to the conclusion that idiopathic pulmonary hemosiderosis in infants is possibly not caused by satratoxins but by other S. chartarum mycotoxins.The optimum temperature for growth for Stachybotrys chartarum is 23 ^oC with a minimum and maximum temperature of 2 and 37 ^oC respectively.

The optimal water activity is 0.98 with a minimum of 0.89. To read more about Stachybotrys chartarum and S. chlorohalonata click here.

Aspergillus flavus

Aspergillus flavus is widely distributed in soil. It is associated with a wide range of stored products such as maize and nuts. In indoor environment it is commonly found on damp walls, wallpaper, floor and carpet dust, tarred wooden flooring, humidifiers and HVAC fans, bakeries, shoes, leather, and bird droppings. Strains of this mould may produce aflatoxin, a class 1 carcinogen.

The minimum and maximum temperature for growth are 6 and 45 ^oC, with an optimum at 40 ^oC. The minimum water activity is 0.78 and an optimum at 0.98.

Aspergillus fumigatus

Aspergillus fumigatus is common in composting plant material, woodchips and garbage. Also common in dust infiltrating from outdoor air, carpet and mattress dust, wet building and finishing material, HVAC insulations, fans, filters, humidifier water and potted plant soil. A. fumigatus is a producer of various mycotoxins including gliotoxin, verrucologen, fumitremorgin A & B and fumigaclavines among others. A. fumigatus has an optimum growth temperature at 43 ^oC and minimum and maximum at 10 and 57 ^oC respectively. Minimum water activity is 0.82 and an optimum at 0.97.

Aspergillus niger

Aspergillus niger is found worldwide in soil and plant litter. In indoor environment A. niger is common in floor, carpet and mattress dust, acrylic paint, UFFI, leather, HVAC filters and fans, and potted plant soil. A. niger produces malformins and a few strains also produce ochratoxin A. A. niger requires a minimum temperature for growth at 6 and maximum at 47 ^oC with an optimum at 37 ^oC.

Aspergillus versicolor

Aspergillus versicolor is one of the common indoor molds. It is very common on gypsum board, floor, carpet, mattress and upholstered-furniture dust, and damp walls. A. versicolor produces high quantities of the carcinogenic mycotoxin, sterigmatocystin at water activities (a_w) above 0.95. A. versicolor is generally xerophilic- meaning that it can grow at low water activity (<0.80). The minimum and maximum growth temperatures for A. versicolor(/i> are 4 and 40 ^oC with an optimum at 30 ^oC.Its optimal water activity is 0.95 with a minimum of 0.75.

To read more about Aspergillus species click Aspergillus. The university of Manchester, UK has detailed information on Aspergillus at https://www.aspergillus.man.ac.uk/

 Penicillium chrysogenum

Penicillium chrysogenum is one of the most common indoor molds. It is extremely common on damp building materials, walls and wallpaper; floor, carpet mattress and upholstered-furniture dust. P. chrysogenum produces few detectable metabolites and often none when growing on building materials. Lack of observed effects on persons exposed to high quantities of spores and the production of few metabolites suggest this species may not be an important health hazard. However, some strains may cause allergenic reactions to susceptible individuals. P. chrysogenum can grow at a minimum temperature of -4 ^oC, an optimum of 28 ^oC, and a maximum of 38 ^oC. It has minimum water activity of 0.79 and an optimum at 0.98

Penicillium brevicompactum

Penicillium brevicompactum is common on damp walls and building materials e.g., gypsum board; floor, carpet, mattress and upholstered-furniture dust. P. brevicompactum produces mycophenolic acid. P. brevicompactum can grow at -2 and 30 ^oC with an optimum at 25 ^oC. Its water activity requirements are a minimum of 0.75 and an optimum at 0.96.

Chaetomium globosum

Chaetomium globosum is common on cellulose containing building materials that has been very wet such as gypsum board, cellulose board and wood. C. globosum produces high quantities of chaetoglobosins. The water activity requirement for C. globosum are a minimum of

 Trichoderma species

Trichderma species are frequently found on gypsum board and water saturated wood; floor, carpet and mattress dust; paint; domestic water supply, and HVAC system air. In one study, Trichoderma species were not found to produce detectable quantities of trichothecenes when growing on building materials. Less than 1% of the isolates produced trichodermol or esters of it. Compared with other indoor molds such as Cladosporium, Aspergillus and Penicillium, Trichoderma is not very common indoors.

References

Kuhn, D. M. and Ghannoum, M. A. (2003). Indoor Mold, Toxigenic Fungi, and Stachybotrys chartarum: Infectious Disease Perspective. Clinical Microbiology Reviews, 16(1):144–172.

Nielsen, K.F, (2002). Mould growth on building materials: Secondary metabolites, mycotoxins and biomarkers, Dissertation, The Mycology Group, Technical University of Denmark. 116p

Aspergillus clavatus is often associated with allergic diseases in workers of malt-houses. Aspergillus fumigatus is the most important and well known potential pathogen for humans with weak immunity. It is of great concern in hospital environments. Spores of Aspergillus fumigatus are allergenic and have the ability to bind on lung epithelium causing complications in the health status of asthmatic individuals.

Due to their small size (2-3.5 microns), about 70% of Aspergillus fumigatus spores are able to penetrate into the trachea and primary bronchi. Aspergillus niger and Aspergillus fumigatus are often associated with two respiratory disease conditions: allergic and invasive aspergilloses. Aspergillus versicolor is one of the most common Aspergillus species found in damp indoor environments and is a major producer of one of the liver damaging and carcinogenic mycotoxin.

Sampling For Aspergillus Species

It is rare for an indoor air quality investigation to target for Aspergillus species only. However, situations may arise when sampling is specifically targeted to Aspergillus species or a single species such as Aspergillus fumigatus.

Although sampling for non-viable analysis can be used to sample for members of the genus Aspergillus, it is limited in that species of Aspergillus, Penicillium and even some other unrelated genera are difficult to differentiate based on spore characteristics only. Therefore, sampling for viable analysis or for both viable and non-viable analysis is recommended.

Combining sampling for viable and non-viable analysis has one major advantage. Non-viable sampling could give a better estimation of the total spore concentration for Aspergillus/Penicillium and the results could be obtained within the same day of sampling. Sampling for viable analysis on the other hand could give an estimate of the viable portion of the Aspergillus/Penicillium groups detected with the non-viable sampling.

It is however, important to note that results for non-viable and viable samples sometimes show no correlation. This is understandable because apart from the differences in sampling devices, there are other factors that could influence the results obtained with either viable or non-viable samplers.

For example, spores reported as Aspergillus/Penicillium species may belong to species totally unrelated to either Aspergillus or Penicillium species. In this article we will discuss sampling airborne Aspergillus species for viable (culture) analysis.

Sampling Considerations

The important points to consider when sampling air for members of the genus Aspergillus are:

• Efficiency of the air sampler in collecting small size spores.
• Selection of sampling media.
• Selection of sampling time.
• Selection of sampling location.
• Sampling limitations.

Efficiency of the Air sampler

The size of spores of Aspergillus species ranges from 2 to 10 micrometres (microns). A sampling pump that is most efficient at this size range should be selected. Most volumetric samplers are less efficient for spore sizes less than 5 microns.

Selection of Sampling Media

Aspergillus species can grow over a wide range of substrates. However, with the exception of a few species, they generally grow well on low water activity substrates (that is they are xerophilic). One of the media recommended for xerophilic moulds is Dichloran 18% Glycerol Agar. This is a general-purpose low water activity medium that selectively support the growth of xerophilic moulds or moulds that prefer dry environments. A second advantage of DG18 is that it restricts the colony diameter thus preventing colonies from overgrowing each other and hence easy to enumerate. DG18 also inhibits bacterial growth ensuring that bacteria do not interfere with mould growth.

Selection of Sampling Time

Selection of sampling time is based on the environment being sampled (i.e. whether heavily contaminated or not) and the type of sampler (most samplers have manufacturers recommended sampling time). If the sampling time selected is too long in a heavily contaminated environment then the colonies may be too many to be accurately counted.

Sometimes it is hard to know how contaminated the environment being sampled is. In this case, initial non-viable air samples may be taken and analysed immediately to give an idea of the level of contamination.

Selection of Sampling Location

The sampling location and height from where the samples are taken can influence the results obtained. The location should generally correspond broadly with the breathing zone or about a height of 1.2 meters. If one is interested in detecting the source of Aspergillus growth,samples should be taken near the suspected sources of contamination. Multiple samples are recommended since they would highlight variation of airborne mould concentrations with time and also location.

Sampling Limitations

Air sampling on growth media has one major limitation. Only those mould propagules (spores and hyphal fragments) that can grow on media are detected. Although this may not apply to species of Aspergillus, it is estimated that only 10-15% of airborne mould propagules may be viable.

To see guidelines for interpreting non-viable air sample results click Guidelines for Interpreting Non-viable Air Samples.

To see guidelines for interpreting viable air sample results, click Guidelines for Interpreting Viable Air Samples.

Register for online Mould Training Course today to learn more!

Aspergillus is widely distributed from the arctic region to the tropics. Aspergillus species are frequently found in air and soil.As concerns indoor air quality the most important species are Aspergillus fumigatus, Aspergillus flavus, Aspergillus clavatus, Aspergillus niger, Aspergillus versicolor.

Aspergillus: Should It Worry You If You Find It in Your Home or Office?

MBL is commonly asked if these types of molds are dangerous. In reality, species of Aspergillus affect our lives in several ways:

• Biodeterioration. Species of Aspergillus are capable of utilizing an enormous variety of organic material for food because of their ability to produce a large number of enzymes. Under humid conditions, Aspergillus species grow on leather and cloth fabrics, reducing their value and imparting musty odour to shoes and clothing. Several species are frequently found on grains and exposed foodstuffs where they cause decay and subsequent loss of food.
• Medical Effects. As concerns health, the most important species of Aspergillus are Aspergillus clavatus, A. flavus, A. fumigatus, and species from the group of A. niger, and A. versicolor. These molds have been classified by some authorities as being toxigenic or pathogenic and instant action is required when they appear in occupied indoor environment.
  • Mycotoxins. Aspergillus species produce toxic compounds, the most well known being aflatoxins. Aflatoxin is a class 1 carcinogen produced by strains of Aspergillus flavus and Aspergillus parasiticus. The best known toxic metabolites of A. fumigatus are mainly fumigaclavines A, B, C, and D, spinulosin and tremorgenous toxins, e.g. verruculogen. A. niger strains produce toxic metabolites belonging to malformins A1, A2, B1, B2, C and oxalic acid. On building material, strains of A. versicolor produce the toxic class 2A carcinogenic sterigmatocystin.
  • Opportunistic Pathogens. Aspergillus fumigatus is an animal and human pathogen causing a group of diseases commonly referred to as Aspergilloses. Aspergillosis of the lungs is believed to be the most serious of these diseases and is quite common in birds and various mammals including humans. Other species of Aspergillus associated with Aspergillosis are A. flavus, A. niger and A. terreus. Aspergillus niger has been reported as causing ear, nose and lung infection particularly in immuno-compromised individuals.
  • Allergic Reactions. Many species of Aspergillus produce dry, hydrophobic spores that are easily inhaled. Due to their small size, about 70 % of spores of A. fumigatus are able to penetrate into the trachea and primary bronchi and close to 1 % into alveoli. Inhalation of spores of Aspergillus is a health risk. Aspergillus clavatus is allergenic causing the occupational hypersentivity pneumonitis known as malt worker’s lung.

Occurrence of Aspergillus species in indoor environments

It is generally believed that the amount of airborne spores of Aspergillus spp. in indoor air is higher than outdoors at any given time. In the home, the amount of spores in the air is significantly increased when cleaning is carried out mechanically, for example, when carpets are vacuum cleaned. Some studies on prevalence of Aspergillus species in indoor environment documented A. fumigatus in kitchens and bathrooms, A. versicolor and A. repens in mattresses and carpets, A. versicolor and A. fumigatus in basements, A. fumigatus, A. niger and A. flavus in flower pot soil, A. versicolor and A. fumigatus in various pad materials.

Species of Aspergillus have been isolated from damp walls, wallpaper, PVC/paper wall covering, gypsum board, floor, carpet and mattress dust, upholstered-furniture dust, acrylic paint, UFFI, leather, HVAC insulations, filters and fans, humidifier water, shoes, leather, bird droppings and potted plant soil, plastic and decomposing wood.

References: