Dr Jackson Kung'u- Mold Specialist

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Dr. Jackson Kung’u (PhD)- Mold Specialist.
Phone: 905-290-9101

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Aspergillus

Aspergillus/Penicillium in the Basement

Question: Is Aspergillus/Penicillium spore count in the basement high? We have this smell in our house for some time. We have also arranged for the gas company to come to see if there is gas leak. Last week, we had an air sample taken from our house. The Aspergillus/Penicillium reading from outside was 267 spores/m3 and the reading from the basement was 26,667 spores/m3. I do not know if these readings indicate any significance. Do you have any suggestions for the cause and solutions? Thank you very much for your help.

Answer: I think the Aspergillus/Penicillium spore count in the basement suggests persistent humid conditions. You may want to hire a professional to come and assess the extent of mold growth in the basement, identify the cause (i.e., moisture source) and suggest the best method to fix the moisture problem and remove the mold safely. To control the growth of mold such as Aspergillus/Penicillium the humidity in the basement has to be reduced to a level below 60%. The following techniques can help control moisture in the basement:

  1. Fix leaks, drips, and seepage problems.
  2. Dry wet areas within 24 to 48 hours to prevent mold growth. Thoroughly clean and dry water-damaged carpets and consider removal and replacement of items that appear to be permanently water damaged. Mold and mildew on hard surfaces can be washed and the surfaces dried completely.
  3. Do not finish a basement below ground level unless all water leaks are sealed. A finished basement should also have adequate outdoor ventilation and heat to prevent condensation.
  4. Operate a dehumidifier in the basement, if necessary, to keep relative humidity levels down. But keep in mind a dehumidifier can be expensive to operate.

Health Effects of Mold

All molds are potentially a health hazard. While majority of common molds are not a concern to individuals who are healthy, the health effects of most of the indoor molds are not known. Some symptoms associated with mold exposure are also highly controversial. Health effects of mold include:

1. infection;

2. allergic reactions (i.e., allergy);

3. mycotoxin poisoning.

 Infection

Infection of healthy individuals by indoor molds is very rare. Occasionally, however, immunocompromised individuals may be infected by some opportunistic pathogens such as species of Aspergillus, Penicillium and Fusarium.

Allergic Reaction

It’s estimated that about 20% of the human population is allergic to normal spore concentrations. The rest 80% would require exposure to higher spore concentrations. Health effects of mold partly depends on the amount of mold an individual is exposed to. However, with the large number of mold species and strains growing in buildings and the large inter-individual variability in human response to mold exposure it’s hard to define what is “normal” or “high” mold spore concentration.

Mycotoxins

Apart from infections the most well known health effects of mold is mycotoxin poisoning. Some common molds such as Aspergillus flavus, Stachybotrys chartarum, Fusarium, Alternaria, Paecilomyces, Rhizopus, Trichoderma, and Trichothecium produce substances (mycotoxins) that are toxic to humans, animals or other microorganisms. A number of mycotoxins are not only toxic but are also highly potent carcinogens. Spores of toxin producing molds contain mycotoxins. Majority of mycotoxins are not volatile and therefore mycotoxin exposure is likely to occur through inhalation of spores and dust. Evidence that inhaled mycotoxins affects human health is circumstantial.

Minimizing Exposure To Mold

The best way to deal with the health effects of mold is to minimize exposure to mold. Exposure to mold can be minimized by improving the indoor air quality. Here are some steps one can take:

  • Controlling humidity and letting more air into the house by ensuring sufficient ventilation. This prevents moisture from building up on walls and windows. If there is excessive humidity, mechanical ventilation such as a fan may be needed to get rid of it.
  • Measuring humidity by using a hygrometer to see if a de-humidifier is needed. The relative humidity should be kept below 50% in summer and 30% in winter.
  • Repairing leaky roofs, walls, and basements.
  • Cleaning moldy surfaces with a detergent.
  • Keeping the house clean and dust-free.
  • Regularly cleaning and disinfect humidifiers, de-humidifiers, and air conditioners.

If you have a question regarding health effects of mold, contact us at 905-290-9101.

Mold Growth, Moisture, and Your Home

Moisture is one of the key requirements for mold growth in homes. There are different types of mold. Some molds require relatively very low levels of available moisture for them to grow. These types of mold are referred to as xerophilic and are likely to be found in almost every home. The common xerophilic fungi belong to the genera Aspergillus, Penicillium and Wallemia. Some other molds require wet or highly damp prolonged conditions. These are referred to as hydrophilic (“water loving”) fungi and their presence in homes is an indication of moisture damage. Examples of indicators of moisture damage include Chaetomium, Stachybotrys and Fusarium.

Mold growth: Penicillium on wood

Mold growth: Penicillium on wood

 

Mold Growth Control

The best way to control mold growth is to eliminate moisture. Strategies to control mold growth involve:

  • Reducing humidity. It’s recommended that relative humidity be maintained at or below 60%.
  • Inspect the building regularly for signs of mold, moisture, leaks, or spills and take appropriate action
  • Respond promptly when you see signs of moisture and/or mold, or when leaks or spills occur
  • Reduce potential for condensation on cold surfaces such as windows, piping, exterior walls, roof, or floors by adding insulation
  • Frequently clean floor, carpet, and remove dust on surfaces. This reduces the amount of spores that would otherwise start new mold growth when moisture becomes available.

Biodeterioration

Biodeterioration is a terminology used to describe any undesirable change in the properties of a material caused by the vital activities of organisms.

Fungal growth requires suitable temperature, moisture and air (oxygen). Fungi are heterotrophs that acquire nutrients by absorption. They secrete hydrolytic enzymes (exoenzymes) and acids to decompose complex molecules into simpler ones that can be absorbed and used as nutrients. Hence, they are believed to be potential contributors to biodeterioration of different kinds of materials containing cellulose, silicate mineral (mica and orthoclase), iron and magnesium-bearing minerals (biotite, olivine, pyroxene) etc.

Fungi cause biodeterioration to many materials including:

  • building materials
  • animal feeds
  • electrical equipment
  • food including meat, fruits and grains
  • fuel including jet fuel
  • glass and optical equipments
  • gunpowder
  • leather
  • monuments
  • paint
  • paper
  • tobacco etc.

 How are Fungi involved in biodeterioration?

The rate of biodeterioration depend on prevailing environmental conditions and the fungus involved. There are different mechanisms of biodegradation. These include microbial corrosion, hydrocarbon degradation and biodegradation of cellulose.  Aspergillus niger, Chaetomium globosum, Scopulariopsis brevicaulis, Trichoderma koningii, Trichothecium roseum and Eurotium chevalieri are cellulolytic fungi. Their efficiency to degradate cellulosic (cellulose containing) materials is due to their ability to produce large amounts of cellulase enzymes. 

Stachybotrys chartarum is a common fungus growing on paper (such as that covering gypsum wallboard) in damp buildings.

Some fungi cause blue stain and soft rot of wood, discolouration and loss of strength of cotton materials.  Many fungi spoil food in storage. Aspergillus flavus grows on peanuts and many other substrates, producing a mycotoxin called aflatoxin, which contaminate food and causes liver damage. Fusarium graminearum grows on feed corn and produces the  mycotoxin zearalenone that causes oestrogenic syndrome in animals.

Through the action of excreted oxalic and citric acids fungi can deteriorate marble, limestone, granite and basalt. Several species of fungi are involved in biodeterioration of stone monuments in different countries. Some of these fungi are Aspergillus elegans, Aspergillus flavus, Aspergillus nidulans, Aspergillus niger, Aspergillus versicolor, Alternaria sp, Cladosporium cladosporioides, Cladosporium sphaerospermum, Cunninghamella  echinulata, Curvularia lunata, Fusarium roseum,  Gliocladium virens, Penicillium crustosum, Penicillium glabrum, Penicillium chrysogenum (=Penicillium notatum), Rhizopus arrhizus.

Biodeterioration is a problem worldwide. Several control measures have been applied to prevent the biodeterioration. These include use of fungicides, biological control, prevention of biodeterioration by control of environmental conditions, periodic cleaning of dirt, dust and spores, and use of radiation.

Black Mold Growth In Buildings

The black mold, Stachybotrys chartarum, is the mold feared most by the general public. It’s one of the molds used as indicators of moisture damage in a building. Black mold thrives on wet materials rich in cellulose. It’s commonly isolated from soil and decaying plant matter such as straw. In buildings black mold is found growing on very wet gypsum board, wallpaper, cotton fabrics and textiles,  and other materials containing cellulose.

Unlike some other indoor molds such as Aspergillus and Penicillium that produce dry spores, spores of black mold (Stachybotrys) are produced in wet form. This means that the spores of Stachybotrys do not easily become airborne until they dry out or get disturbed say during renovations. Therefore, if pre-remediation air samples, for example, contain a few spores of black mold, it’s important to try and locate the source of those spores. The mold is most likely to be located in areas with a history of moisture damage.

Medical Significance Of Black Mold

While black mold is highly publicized as the cause of all sorts of health problems, it’s medical significance still remains controversial.