Mold spores are ubiquitous in the indoor and outdoor environment. Damp and moldy conditions indoors have been associated with adverse health effects such as the development and exacerbation of asthma, bronchitis, allergic rhinitis and other respiratory tract symptoms. Please note that if you or your client are concerned about specific health effects, you should consult a medical professional. In this post, we will be discussing the laboratory methods used for identifying molds and how they can inform the remediation process.
The job of an industrial hygienist, mold inspector, or a remediation company is to help find sources of mold growth in the indoor environment, remove mold and remedy the moisture issue making sure building occupants are not exposed unnecessarily to dampness and mold. During those investigations, laboratories will provide objective analysis to the experts in support of their mold assessment. Here are three ways mold growth is analyzed by the laboratory and what the results can tell you about how to tackle your mold problem.
#1 Direct Microscopy
Direct microscopy is the most common way to analyze mold and offers a quick and cost-effective way of providing lab data to assist with a mold inspection. The results of direct microscopy are typically expressed as spore count. In some cases, labs will provide qualitative direct examination of surface samples that give more descriptive results including fungal structures that indicate active mold growth.
One of the most common applications of direct microscopy is to assess air samples for mold spores. This is often referred to as the “spore trap” method. There are many different types of specialized devices that can be used. We do not have the space to go into specifics here, but our experts would be happy to discuss your situation and provide insights into the best equipment to use. We can also help answer questions about how many samples you should collect to ensure defensible results. You can contact us here.
Spore trapping is often used for a comparison between outdoor and indoor concentration and types of airborne spores. Without mold growth indoors, mold spore concentrations are expected to be less than but similar in distribution to outside concentrations. If one or more spore types are present inside in higher concentrations than expected, you may be looking at indoor mold sources. Airborne spore counts can also identify a case of hidden mold, e.g., behind a wall or under a carpet, when growth is not outwardly visible. Water-loving (hydrophilic) molds can be indicators for dampness and moisture.
In addition to air testing, direct microscopy can be also performed on tape lifts and bulk materials to determine the type and amount of mold and growth activities. Remember to always wear personal protective devices, such as respiratory filters, as the process of collecting mold samples will release spores into the air. Better yet, engage a professional mold services provider to conduct your sample collection. They will have the right equipment and take the proper precautions to avoid exacerbating the problem.
While the data from microscopy alone should not be used to make a mold assessment of an indoor environment, it can back up a visual inspection and be very valuable in providing additional information and insights. For further details on how to address active mold growth, always refer to any appropriate governing authorities. For example, New York’s labor law details the specific requirements for a mold remediation in the workplace, including identification of the mold and the cleanup procedures to be followed to ensure that all the mold has been removed. The CDC also offer mold abatement recommendations on its website: CDC Mold Cleanup Guidelines and Recommendations. Lastly, due to the potential adverse health impacts of an active mold growth, it is usually advisable to work with a professional, such as a trained industrial hygienist or certified mold abatement service provider.
#2 Mold Sample Culturing
There are many scenarios where a viability assessment and species identification are critical as some species of mold are more likely to cause adverse reactions than others. For example, if specific fungal species such as Aspergillus fumigatus have been associated with allergic reactions of an individual or if we are dealing with infections and need to match species, culturing is often necessary.
Mold culturing takes direct analysis a step further by allowing spores to germinate in a growth medium to form larger colonies with more distinct characteristics. Once growth occurs, genus or species can be determined for the most part. It takes an experienced mycologist to correctly identify mold to genus or species level and some molds are easier to identify than others. Even the most experienced analyst will not be able to identify all fungal colonies to a species level, especially if the colony does not develop fruiting bodies (reproductive structures).
Some fungi/mold cause infection. Fungal infections such as allergic bronchopulmonary aspergillosis (ABPA) can occur. ABPA is estimated to affect between 1 and 15% of patients with cystic fibrosis. In addition, roughly 2.5% of adults with asthma are estimated to have ABPA, which translates to approximately 4.8 million people worldwide. The effects of exposure to secondary fungal metabolites such as mycotoxins in damp/moldy homes is a concern, although it is still not fully understood and needs more research to determine their role and impact to human health.
Species identification is also critical in some industries. For instance, when sampling in cleanrooms for USP <797> to monitor sterile compounding environments it is important to understand not only if there is any microbial contamination present but also what type of microbe we are dealing with. Fungal contaminations are of particular concern because if they reach the human bloodstream or spinal fluid via an injectable compounded sterile preparation, they are more difficult to treat than most bacterial infections and can be fatal. Species identification can also help determine potential contamination sources and the appropriate remediation approach.
Finally, mold species identification is critical in some healthcare settings, particularly surgery centers, cancer centers, and other facilities that house or treat immunocompromised patients. For instance, Aspergillus is a genus of common mold that is relatively benign in most settings unless, as mentioned above, the individual suffers from ABPA. However, Aspergillus is commonly associated with healthcare-associated infections, with some species causing mortality rates as high as 60%, according to the CDC.
#3 Mold Analysis by Polymerase Chain Reaction (PCR)
Mold analysis by Polymerase Chain Reaction (PCR) is a method that can be useful for detecting small amounts of mold through the amplification of specific segments of DNA. This method involves extracting DNA from an environmental sample and adding it to a reaction mixture containing primers and a probe specific to the mold being tested. When amplified in a thermocycler, the targeted DNA sequences are exponentially replicated, allowing for detection of selected molds.
Mold Analysis – When a Laboratory is Needed
One of the questions that often gets asked in any discussion of mold analysis is whether laboratory testing is really needed. In most cases, laboratory testing is suggested or recommended. I have on many occasions observed what I believed were mold. However, samples that were collected and examined under the microscope turned out to be false. Laboratory testing is important to confirm and identified suspect mold. Moldy areas with properly identified mold types may also indicate a larger problem associated with water intrusion, leaks, or high humidity leading to condensation issues requiring additional action to address the source of moisture.
If you manage an older, multi-residential property (or are considering an investment in one) mold analysis can give you insights into hidden mold sources and inform your remediation strategies. It’s not uncommon for institutions, such as schools, correctional facilities, assisted living facilities, and so on, to conduct regular mold monitoring. It helps promote healthy work and living spaces and can protect more vulnerable individuals from severe mold-related illnesses.
If you are responsible for facilities used in any of the industries with environmental compliance regulations or that regularly serve immunocompromised people, then laboratory analysis, including species identification and viability assessment, is essential. This would include compounding pharmacies and healthcare facilities, such as hospitals, surgery centers, and cancer treatment clinics. Other industries, such as pharmaceutical and food manufacturing, may also benefit from frequent mold monitoring as some species can impact shelf life and food quality.
For more information on Pace® mold testing services, download our Information Sheet. If you’re still not sure whether you need to contact a lab for help in solving your mold issues, reach out to us. We’re happy to provide insights on your particular scenario.