Dr. Lauren Tessier is a naturopathic physician practicing in Waterbury, VT, and New York, NY. She specializes in treating mold-related, biotoxin and other complicating illnesses and is CIRS-certified. Learn more about her practice “Life After Mold” by visiting www.lifeaftermold.com. You can also find her on Twitter, Instagram and Facebook.
Stachybotrys chartarum, more commonly known as “black mold,” was first identified in Prague in 1837. A Czech mycologist discovered the mold growing on an indoor wall of a home. Despite an early discovery, the term “black mold” only became part of the normal lexicon of the average homeowner in the 1990’s, when the nightly news brought the phrase “black mold” into homes across America. Though black mold is considered harmful, the details are still in question. This article is meant to help inform those who are worried about being exposed to black mold.
A black mold scare
In 1993, a horrible mystery brought 10 cases of bleeding lung syndrome in infants in Cleveland. These cases were later linked by the CDC to “toxic” black mold from standing floodwater remaining in homes. The CDC later issued an update that the association is unproven and requires further study, though the controversy remains until today. Since that time, stories of houses and property lost to water damage and resultant mold growth became a cause for concern for every homeowner nationwide.
What is black mold?
One shade, many types
“Black mold” is the misnomer often assigned to the mold species Stachybotrys chartarum, which is just one of many species of black mold. Another example is Aspergillus niger. It may surprise you that there are more than 60 other species of black mold that may have deleterious effects on human health, though this article will only concern Stachybotrys chartarum. Black mold gets its name because it contains melanin, which is responsible for its coloration. Interestingly, the melanin offers protection to the mold colony from the damaging and oxidizing effects of their environment.(Eisenman & Casadevall, 2012).
How common is it?
Commonly found indoor molds include Penicillium, Cladosporium Aspergillus, Alternaria, and Fusarium.
Stachybotrys, although notorious in name, is less common in water damaged buildings when compared to other molds. While it does not occur as often as other molds, it is not rare and should be addressed appropriately.
Most molds require humidity levels ranging from 35%-70%, while Stachybotrys prefers general humidity over 90%. The lower humidity range associated with common molds is more representative of what is found throughout the average home. Therefore, it is more likely that Stachybotrys will only reside in high humidity areas, while the other common molds have a higher likelihood of residing throughout the house.
Where is mold found in a home
A research study found that Stachybotrys preferred a very high relative humidity within walls–approximately 97%–which indicates that relative humidity could be an important risk factor (Boutin-Forzano et al., 2004). For black mold, you may consider smaller microclimates that may harbor such humidity levels: sweating pipes, under sink cabinets, front loading washing machines, standing water, roof leaks, damp cars, windows with condensation, etc. Generally, common places to check for mold growth include the kitchen, bathroom and laundry room.
However, humidity alone is not the only requirement for mold growth–mold requires nutrients to grow. Any environment that has nutrients like cellulose (plant fibers) or other organic matter can harbor mold if the humidity level is right. To further enable mold growth, an environment that has poor air flow and minimal disruption is ideal. For example, you can find mold on wallpaper, furniture, drywall, overly-packed bookshelves or overstuffed closets.
How can you be exposed to black mold?
You can be exposed to black mold, or any species of mold, by breathing in microscopic mold particles in the air, or through consumption of food that contains it.
Stachybotrys is unique because its spores are “sticky” and easily adhere to a surface when the mold colony dries. They are not regularly found in the air unless the mold colony has been disturbed. Though its spores are not readily airborne, black mold can produce other harmful contaminants more easily found in the air (as explained in the next section).
A disruption to a black mold colony can be as simple as slamming a door, opening a window or knocking into contaminated furniture. More force is required for Stachybotrys spores to become airborne, as compared to other commonly found indoor molds (Aleksic et al., 2017).
What about tiny mold toxins aka mycotoxins?
As mentioned above, though the Stachybotrys spores may be sticky and not easily airborne, there are other airborne contaminants to worry about: tiny fragments of mold and special toxins called mycotoxins. These contaminants may cause illness in those who are exposed, with mycotoxins being the most concerning.
You can think about mycotoxins as the mold’s defense: they are used for protection from environmental threats. Mycotoxins are minute organic compounds as small as 0.03 microns. These tiny molecules can stick to particles already floating through the air. Studies have found Stachybotrys mycotoxins on mold fragments that have broken off from a mold colony after it has been disturbed (Brasel et al., 2005). This can be harmful—airborne particles less than 1.0 microns are easily breathed into the respiratory system, where they can cause irritation and potential allergic reactions. If this occurs, mycotoxins could accumulate onto local tissue and ultimately enter the bloodstream. The study by Brasel (2005) cited above showed that trichothecenes could be measured in the blood of people exposed to an indoor environment that had Stachybotrys.
Stachybotrys creates a class of mycotoxins referred to as trichothecenes. Trichothecenes have been widely studied and have been proven to be detrimental to the health of humans, animals and plants. In fact, trichothecenes have been investigated for the purpose of biological warfare (Zajtchuk, 1997); needless to say, they are not something to which you want to be exposed.
Could your symptoms be from a general mold allergy?
Regardless of the species of mold in question, symptoms of a mold allergy can appear very similar, especially when looking at many individuals. So if you see black-colored mold (or some with a greenish tint, as Stachybotrys can also appear this color) and experience allergic symptoms, it could be Stachybotrys, or it could be another species of mold. That said, the same person can react differently to different molds. For example, one person may have severe dry eyes in response to a Cladosporium exposure, while Aspergillus exposure may cause wheezing and asthma-like symptoms.
General allergic impacts of mold
For those people who are sensitive to mold, the CDC lists the following symptoms that mold in general (not specific to black mold) may cause:
- Nasal stuffiness
- Throat irritation
- Coughing or wheezing
- Eye or skin irritation
For people with mold allergies or asthma, exposure to any kind of mold may cause more severe reactions like:
- Shortness of breath
Other symptoms of a mold-related illness
Mold can cause many forms of illness besides well-known mold allergies, including:
- Systemic inflammation
- General irritation
People who more likely to be affected by mold
The CDC also describes who is more likely to get mold infections. People who are more likely to get serious mold infections in their lungs when exposed to any kind of mold may include:
- Those with a weakened immune system (immune-compromised)
- People receiving treatment for cancer
- People who have had an organ or stem cell transplant
- People taking medicines to suppress the immune system
Moreover, there are many modifying factors that can increase or decrease your reactivity to mold, which may include:
- Nutritional status
- Immune system functionality
- Detox capability
- Length of exposure,
- Types of mold and mycotoxin exposure,
- Form of exposure (inhalation vs ingestion)
- Comorbid illnesses
Signs and symptoms of black mold poisoning
Black mold exposure may often present with your typical allergic complaints that are listed above. However, one must be mindful that other non-allergic, mold-related illnesses exist and may present similarly to a mold allergy, but often with more seemingly unrelated symptoms.
Research (Kilburn 2003) has found that people who have been exposed to mixed mold, mold spores and mycotoxins have experienced neurological and behavioral symptoms. These symptoms have been corroborated by other studies like Gordon et al. (2004) and Rea et al. (2003).
Such non-allergic symptoms to mold (including black mold) may include, but are not limited to:
- Cognitive impairment
- Sleep disturbance
- Balance difficulties
- Brain fog
- Circulation issues
- Digestive complaints
- Vision changes
- Muscular pain
- Joint pain
- Neurological complaints
How to get rid of black mold
As mentioned, Stachybotrys can look black or green so color is an unreliable identifier. If you suspect mold exposure and cannot see visible growth, consider hiring a reputable company to complete a mold inspection. You can look for indoor environmental professionals (IEPs) who are certified by the American Council for Accredited Certification (ACAC).
In general, a good IEP will bring plenty of equipment along with them to their site visit, including a particle counter, a hygrometer and a thermal imaging camera. Typically, you should expect them to identify areas of increased humidity along with thermal variations. Please know that a visual inspection is not enough, as water damage and thus mold, can exist in walls and in hidden areas.
How to prevent black mold
The key to preventing Stachybotrys growth is to control humidity. A good rule of thumb is to keep humidity below 50% in the summer, and potentially under 40% in the winter. Be advised that different humidity levels are applicable to different times of the year and different climates. It is best to speak with your local reputable Indoor Environmental Professional (IEP) and local reputable HVAC professional to find the right level for your home.
In general, a dehumidifier can be used to maintain appropriate humidity levels within the home. Be mindful of energy usage, as older models of dehumidifiers can cause large spikes in your electric bill. Consider using an ENERGY STAR appliance that is set to 35% humidity. If you choose to use a dehumidifier, make sure to empty it regularly.
Clean surfaces regularly
One cannot forget that mold requires a medium for growth. Therefore, keeping your living space clean and free of cellulose-rich dust and dirt can go a long way towards preventing mold growth. Consider using non-toxic cleaning products on non-porous surfaces, allowing the surface to dry thoroughly after cleaning. Dry static dusters or cloths can also go a long way towards picking up leftover particulate matter.
Maintain good ventilation
The other cornerstone of mold prevention is maintaining good ventilation. Good ventilation ensures circulation of air, which may help reduce humidity if the air is vented to the exterior of the home. Moreover, mold prefers an undisturbed environment and adequate ventilation makes it all the more difficult to grow.
Use an air purifier
Although air purification cannot reverse structural mold damage to homes, it can help to reduce mold exposure. Recall that mold fragments are small and can become airborne, and may cause allergies while also carrying dangerous mycotoxins.
A HEPA filter is the traditional method of air purification and can address some mold spores, though given the right conditions, there is a potential for mold to grow on the filter surface. HEPA filters are rated to remove 99.97% of particles that are 0.3 microns or smaller. Mycotoxins that are not bound to larger mold particles are much smaller than this–typically 0.03 microns in size.
Unbeknownst to the mycologist who discovered the infamous black mold (Stachybotrys chartarum) in 1837, his discovery would lay the foundation for the timeless struggle between the homeowner and the indoor humid environment. Though black mold is harmful, there are ways to remove and prevent it from growing in your home. Getting rid of visible mold and taking the preventive steps listed above can protect you and your family from airborne mold, including the health effects of black mold.