The awareness of toxic mold’s effect on human health has increased dramatically over the past few years. But mold is only one of the many biotoxins found in water-damaged buildings, and the illness caused by exposure to these toxins is much more complex than most clinicians and patients assume.

Over the last several years, I’ve written extensively about the importance of nutrition, physical activity, stress management, sleep, social connection, pleasure, and spending time outdoors. There’s no doubt that these factors are vital for all of us.

But it’s also true that there are other factors that are just as important to our health, yet far less often considered. One of these is toxic burden.

Toxic burden is determined by two factors: the levels of toxic chemicals and microorganisms that we’re exposed to, and the function of our innate detoxification system. If our exposure to toxins is high and our detoxification system is compromised—due to genetic predisposition, environmental factors, or both—then our toxic burden will be high.

The toxins that adversely affect our health include chemicals (e.g., BPA, phthalates, pesticides), heavy metals (e.g., mercury, arsenic, lead, cadmium), and biotoxins (toxins produced by living organisms like mold, bacteria, dinoflagellates, and blue-green algae).

Toxic mold illness has received a lot of attention recently, including a recent documentary created by Dave Asprey of Bulletproof.

While this is surely a positive development, there are a number of misconceptions and misunderstandings about mold illness that I’d like to address in this article. So let’s get to it!

#1: Mold Illness Is Not Just Caused by Mold

Yes, I know this doesn’t make sense. Of course mold illness is caused by mold. That’s why it’s called mold illness!

However, what we often refer to as “mold illness” is actually a much more comprehensive and multi-faceted syndrome now known as chronic inflammatory response syndrome, or CIRS.

CIRS was originally defined by Dr. Ritchie Shoemaker, a former family physician in Maryland. (Dr. Shoemaker is now retired, but he is still actively involved in raising awareness and advancing the understanding of CIRS.

Is the air quality in your home or workplace making you sick?

In the late 1990s, Dr. Shoemaker discovered a connection between a mysterious illness that some of his patients were experiencing and a toxin produced by a fish-killing dinoflagellate called Pfiesteria. Since then, Dr. Shoemaker has linked a similar kind of illness to toxins from a wide variety of microorganisms and chemicals.

These agents—which are collectively referred to as “biotoxins” and are often (but not always) encountered in water-damaged buildings—include (1):

  • Fungi
  • Bacteria (possibly including Borrelia, Babesia, and other organisms transmitted by tick bites)
  • Actinomycetes (gram-positive bacteria from the order Actinomycetales)
  • Mycobacteria
  • Mold
  • Mold spores
  • Endotoxins (aka lipopolysaccharides, or LPS; cell wall components of gram-negative bacteria)
  • Inflammagens (irritants that cause inflammation and edema)
  • Beta-glucans (diverse group of polysaccharides)
  • Hemolysins (exotoxins produced by bacteria capable of destroying cells)
  • Microbial volatile organic compounds (mVOCs; organic compounds released by microorganisms when there is adequate food supply for such “secondary metabolite production”)

Nearly everyone will become ill when exposed to sufficient levels of these biotoxins, but most people recover once they are removed from exposure. Their detoxification system is able to recognize the biotoxins in their bodies as toxins and eliminate them via the normal mechanisms.

However, a minority of people have HLA (human leukocyte antigen) genes that prevent their bodies from being able to recognize and thus eliminate biotoxins. The biotoxins will remain in the body and trigger a chronic, systemic inflammatory response. These are the people that develop CIRS.

#2: CIRS Is Much More Common Than You Might Think

According to Dr. Shoemaker’s research, roughly 25 percent of the population is genetically prone to develop CIRS if two conditions are met:

  1. Sufficient exposure to biotoxins
  2. A “priming” inflammatory event (something that triggers and activates the immune system, such as a serious upper respiratory tract infection or a tick-borne illness like Lyme disease)

Dr. Shoemaker also estimates that 2 percent of the population has genes that render them highly susceptible to developing a multi-system, multi-symptom illness after prolonged or repeated exposure to biotoxins. (Side note: unfortunately, I am part of that 2 percent, which could explain a lot about my past history with chronic illness!)

This suggests that roughly 1 in 4 people have the potential of developing CIRS when exposed to biotoxins. But how common is exposure to biotoxins?

Unfortunately, the answer is: extremely common.

According to a report entitled Implementing Health-Protective Features and Practices in Buildings issued by the Federal Facilities Council, 43 percent of buildings they examined had current water damage and 85 percent had past water damage. When water damage occurs, mold can grow in as little as 24 to 48 hours.

As alarming as these numbers are, they don’t tell the whole story. Although water damage is probably the biggest concern, mold and other biotoxins can also develop in buildings that are not water-damaged but have indoor humidity levels above 50 to 60 percent. In fact, many experts recommend maintaining indoor humidity levels between 30 and 50 percent for preventing the growth of mold and other biotoxins.

Here’s a list of steps that you can take to minimize biotoxins in your home and improve indoor air quality 

  • Fix plumbing leaks and other water problems as soon as possible. Dry all items completely.
  • Scrub mold off hard surfaces with detergent and water and dry completely.
  • Discard absorbent or porous materials, such as ceiling tiles and carpet, if they become moldy. Don’t paint or caulk moldy surfaces.
  • Clean and repair roof gutters regularly.
  • Keep air conditioning drip pans clean and the drain lines unobstructed and flowing properly.
  • Make sure the ground slopes away from the building foundation, so that water does not enter or collect around the foundation.
  • Keep indoor humidity between 30 and 50 percent. Relative humidity can be measured with a moisture or humidity meter, a small, inexpensive ($10 to $50) instrument available at many hardware stores. Venting bathrooms, dryers, and other moisture-generating sources to the outside; using air conditioners and de-humidifiers; increasing ventilation; and using exhaust fans when cooking, dishwashing, and cleaning can all help to reduce indoor humidity.
  • Do not install carpeting in areas where perpetual moisture problems may develop (i.e., in a bathroom).

Another helpful intervention is to use air filters and purifiers/sanitizers. I will write an article discussing them in more detail soon. For now, I will tell you what I use and recommend to my patients:

  1. A HEPA filter that is capable of removing ultrafine particles (<0.1 microns) like mold, dust, pet dander, VOCs, and even viruses from the air. These ultrafine particles represent 90 percent of all airborne pollution that you breathe.
  2. An air sanitizer that eliminates allergens, odors, mold, and germs.

The number and range of devices on the market in both of these categories is mind-boggling, and I’ve spent countless hours figuring out the best options for our home. My research is ongoing, but currently this is what we are using:

  • An IQAir HealthProPlus. IQAir makes HEPA filters that employ a four-stage filtration process (which includes activated carbon) to filter particles all the way down to 0.003 microns—the smallest particles that exist—with a guaranteed efficacy of more than 99.5 percent. We have one of these in the main living area of our home and one in the basement. Important note: is not an authorized reseller of IQAir, so if you purchase from there the warranty won’t be valid. I recommend purchasing directly from IQAir or from one of their authorized resellers.
  • Blueair Sense filters. Blueair filters use “HEPASilent Technology,” which combines electrostatic and mechanical filtration to capture 99.97% of airborne particles down to 0.1 microns in size. We use these in bedrooms and my home office because they are smaller, quieter, and more energy efficient than the IQAir HealthProPlus units.


#3: CIRS Is Frequently Missed or Misdiagnosed

As I mentioned in #2, up to 25 percent of the population is susceptible to CIRS and perhaps a majority of buildings are either water-damaged or have conditions that make mold growth possible. Combine these factors with the increase in inflammatory diseases (which can serve as priming events) that has occurred over the past few decades and you have an environment that is ripe for CIRS.

Unfortunately, the vast majority of patients with this condition have not been properly diagnosed or treated because conventional doctors—and even many functional and integrative medicine specialists—simply aren’t looking for it. The fact that CIRS patients also typically meet the criteria for other syndromes and diseases like fibromyalgia, ME/CFS, post-treatment Lyme syndrome (PTLS), and multiple sclerosis (MS) compounds the problem.

CIRS patients present with a wide range of symptoms, including:

  • Fatigue, weakness
  • Post-exertional malaise
  • Memory problems, difficulties with concentration and executive function
  • Disorientation and confusion
  • Headaches
  • Vertigo, lightheadedness
  • Muscle aches, cramping, joint pains without inflammatory arthritis
  • Hypersensitivity to bright light, blurred vision, burning or red eyes, tearing
  • Cough, asthma-like illness, shortness of breath, chronic sinus congestion
  • Air hunger or unusual shortness of breath at rest
  • Chronic abdominal problems including nausea, cramping, secretory diarrhea
  • A propensity to experience static shocks

As you can see, these symptoms are “non-specific,” which means that they don’t conclusively identify CIRS (or any other disease) by their mere presence.

Dr. Keith Berndston, a physician in Park Ridge, Illinois, has written a thorough summary of CIRS that I highly recommend reading. In it, he highlights the following criteria that a patient must meet to be diagnosed with CIRS (4):

  1. History, signs, and symptoms consistent with biotoxin exposure. In cases of mold toxicity, history should include exposure to toxin-producing molds as documented by the EPA-approved ERMI test (more on this in point #4 below). In other cases (microcystin, ciguatera, etc.), history should include likely exposure or laboratory evidence of exposure.
  2. A genetic predisposition to biotoxin-related illness based on identification of an HLA-susceptible haplotype.
  3. Abnormalities documented by visual contrast sensitivity (VCS) testing. VCS testing measures your ability to see details at low contrast levels. Dr. Shoemaker and Dr. Ken Hudnell—a principal investigator for the U.S. EPA’s National Health and Environmental Effects Research Lab and an expert on how neurotoxins affect the physiology of vision—discovered that the biotoxins affect the optical nerve and decrease the ability to detect visual contrast.
  4. Biomarkers consistent with the neuroimmune, vascular, and endocrine abnormalities that characterize CIRS. If you have a history consistent with biotoxin exposure, a susceptible genotype, and an abnormal VCS test, you are very likely to show the laboratory abnormalities seen in CIRS. Major and minor criteria are a work in progress.

The VCS test is best performed in the office of a CIRS-aware clinician. However, there are two online versions that can be used as a starting place.

The first VCS test is available at Dr. Shoemaker’s website, Surviving Mold, at a cost of $15. This is a Functional Visual Acuity Test (FACT) that uses a scoring algorithm developed by Drs. Shoemaker and Hudnell to determine the likelihood that a patient is being adversely affected by biotoxin exposure.

The second VCS test is available at The raw (unconverted) scores and the contrast sensitivity curve are provided for free, and a $10 donation is requested (but not required) for the upgraded results with detailed analysis and interpretation and a PDF that can be downloaded and shared. now offers what they call an Online Contrast Sensitivity Test, which addresses one of the primary shortcomings of online VCS testing: the variability in how different computer monitors and displays handle visual contrast. The OCST features full display calibration, which adapts the test images to each user by taking into account both their display size and individual display characteristics/properties, like their video card, video drivers, operating system and display settings, including contrast, brightness, gamma, etc. As far as I know, this is the only FACT-based online VCS test that controls for display calibration.

In practice, I think both of these tests can be used successfully as screening tools, but the OCST offered by has the advantage of full display calibration, which allows for accurate results across any device (helpful in re-testing and tracking progress if the patient is re-taking the test on an iPad, for example, if the original test was done on a laptop computer).

The VCS test is so accurate that, if it is positive, there is a 92 percent chance that the patient has CIRS. That said, it’s important to note that a positive VCS test cannot be used to rule CIRS in or out on its own, and I have definitely had patients that passed the VCS test who went on to be positive for CIRS, and vice versa.

A list of the biomarkers that constitute a CIRS diagnosis can be found on Dr. Shoemaker’s site. However, if you fail the VCS test, and/or suspect you may have CIRS, I strongly recommend finding a CIRS-aware clinician in your area. You can start with the list of clinicians that have been certified by Dr. Shoemaker on his website. There are other clinicians, like those of us at California Center for Functional Medicine, that are familiar with CIRS and are actively diagnosing and treating patients for it, but are not yet certified.

Diagnosing and treating CIRS is not a “DIY proposition,” as it involves a lot of nuance and complexity that isn’t always apparent to clinicians and patients that are new to the condition. For example, C4a has to be run through Quest Diagnostics and then sent out to a specialized lab called National Jewish Laboratories in order to get an accurate result. I can’t tell you how many times patients have come to me with a C4a result run through Labcorp or another lab. It’s painful to have to tell them that we need to run these (sometimes expensive) labs again because they weren’t done properly in the first place.

For much more on CIRS diagnosis and pathology, check out my recent interview of Dr. Shoemaker on my podcast, Revolution Health Radio.

#4: Removal from Exposure Is the First Step in Successful Treatment …

Dr. Shoemaker has developed a multi-step protocol for treating CIRS (it ranges from 11 to 14 steps, depending on how you count or combine the steps).

The first step in the protocol is removing the patient from exposure to the biotoxins. This involves testing all environments (home, workplace, recreational) that the patient spends significant amounts of time in throughout the course of his or her daily life. If mold or other biotoxins are identified, those environments must be successfully remediated (followed by taking adequate measures to prevent recurrence), or the patient must relocate to another home or workplace.

As both a clinician and someone dealing with CIRS myself, I have found step one to be by far the most difficult step in the protocol. Here’s why.

Many mold inspectors are not using comprehensive, accurate testing methods. If you call up a local mold inspector and ask him to come assess your property, chances are he will do a visual inspection and take some air samples. Both of these methods can yield useful information, but on their own, they are not enough.

Air sampling does not allow identification of particular species of Penicillium, Aspergillus, Wallemia, etc., which is important because different species have different health effects. In addition, air sampling devices only collect a small sample of air from directly around the device. This matters because mold spores have different molecular weights, and some do not remain airborne for long.

A better method of initially screening a building for mold is the ERMI test. ERMI stands for Environmental Relative Moldiness Index. It utilizes quantitative polymerase chain reaction (MSQPCR) technology to identify mold in dust that has settled in buildings.

The ERMI test was developed by the EPA as a means of determining the relative “moldiness” of a home compared to a group of reference homes that do not have mold. Thirty-six species were divided into 26 species/clusters of molds associated with water-damaged buildings (Group 1) and 10 common species not associated with water-damaged buildings (Group 2). The mold index is the sum of logs of Group 1 minus the sum of the logs of Group 2 in a building. The ERMI has been validated in several peer-reviewed studies (5, 6, 7, 8).

Dr. Shoemaker further refined the relevance of ERMI testing to CIRS patients by creating the HERTSMI-2 scoring system. This is a weighted score that takes the relative levels and danger of particular mold species into account.

The advantage to the ERMI is that it can identify the exact species of various molds present, and it will identify spores that are not airborne. However, it is crucial to understand that not all labs that perform the ERMI test are using the correct methodology.

In order to ensure reliable and accurate results, labs that perform ERMI testing must follow the EPA patent and laboratory procedures exactly. Otherwise, whatever results the test returns will not be validated.

As Dr. Shoemaker explained in a recent article, one of the most prominent labs performing ERMI testing, ESML (also the lab behind MyERMI), is not following these procedures and is currently under investigation by the EPA. Several CIRS-aware physicians had noticed that levels of Wallemia, a particularly problematic species of mold, tended to be under-reported on the ESML test. These false negatives could lead to someone erroneously assuming their home or workplace is safe, when in fact it is not.

EMSL has apparently promised a refund to everyone who has had an ERMI test run through its lab in the past three months. If you fall into this group, I suggest you contact the company.

It’s worth noting that no single test—including ERMI—is reliable as a means of assessing whether biotoxins are present in a building. There is no substitute for an experienced mold inspector that is using evidence-based methodology. (I just wish they were easier to find!)

#5: … but Removal from Exposure Isn’t Enough for Most CIRS Patients

While removal from exposure is an important first step, as I mentioned above, there are at least 10 other steps in the protocol.

People with CIRS have genetic mutations that make them unable to remove the biotoxins that have accumulated in their bodies. This means that getting away from the biotoxins may stop them from building up further, but it will not remove them.

Removal of biotoxins in patients with CIRS usually begins with binders like cholestyramine or Welchol. Other steps include eradicating biofilm-forming staph colonizations that tend to develop in the nasal passages of CIRS patients and correcting high/low MMP9, ADH/osmolality, C4a, TGF-b1, VEGF, and VIP.

In an ideal world, we’d have CIRS-aware physicians in every city and town. Unfortunately, that is not the case. There are currently only a few Shoemaker-certified practitioners, and perhaps several others that are not certified but are actively treating CIRS. Please share this article with those you think may be interested so we can help to spread awareness of this debilitating yet under-recognized condition.