Flashback Friday - Episode 429 - J. David Miller PhD Allergens & Mold, What Every Practitioner Should Know!

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Flashback Friday - Episode 429 - J. David Miller PhD Allergens & Mold, What Every Practitioner Should Know!

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“Dust mites, cockroaches and mold oh my!”

J. David Miller, PhD FAIHA was our guest on today’s episode of IAQradio. Dr. Miller is Professor, NSERC Industrial Research Chair in Fungal Toxins and Allergens at Carleton University in Ottawa, Canada. David Miller knows much about many issues of interest to IAQradio listeners.

Nuggets mined from today’s episode:

IAQradio listeners approach mold from differing perspectives and vantage points. Remediators, home inspectors, industrial hygienists face differing challenges. Now the allergy community has focused on fungi. Patients with “mold” allergies often go to allergists. Allergist rely upon what they learned in medical school and good advice from expert AAAAI committees.

In 2008 the American Academy of Allergy, Asthma & Immunology set about updating clinical practice information on the allergens that mainly occur in buildings. These are called ‘practice parameters’. This involved an expert committee that reviewed 100s-1000s of papers to discern how to diagnose and treat the allergens being studied and what conditions and materials in buildings favor allergens and what medical and environmental interventions are effective. When each document was drafted, it was posted for comment from AAAAI members and the public. The comments were then addressed and a manuscript was submitted to a leading allergy journal. After peer review, the parameters were published and made available.

Led by Dr. Jay Portnoy, a leading academic allergist and clinician, the environmental allergens workgroup reported on furry pets, rodents, cockroaches and house dust mites. The latter two parameters have quite a lot of information on the pertinent building science and allied issues. For example, the cockroach parameter provides guidance on how to evaluate and select pest management firms and/or choose chemicals (Portnoy et al. 2013a). When the house dust mite parameter was published in late 2013, the panel set about to work on dampness and fungi.

A historical review of dust mites provides insight into the how evidence based medicine works. We now know that dust mites cause allergy and asthma we haven’t always known this. In the middle-late 1960s researchers in Holland and Japan theorized dust mites were a health concern. These early researchers were scoffed at.

How we learn about allergic disease in humans: someone first makes an association, then the allergen must be isolated and characterized, then tools must be developed to measure concentrations of the allergen in the environment co-incident with measuring IgE antibodies to the allergen in affected people. When these steps are completed, many studies are done in different populations. If these show strong positive associations, this information taken together provides satisfactory evidence that the allergen is causally linked to disease. As noted, for house dust mite allergens where primarily two proteins are involved, this process took about 20 years. Finally, in 1988 the WHO agreed that dust mites caused asthma.

Dust mites are little and taught us a lot.

House dust mites were first reported in Canada in 1969 and in the USA in 1970. When first reported they were rarely found. They became more commonly found by 1980 and found everywhere by 1990. The ancestral dust mites originally came from near Australia. Adding carpeting, accumulation of more fine dust and higher humidity provided an environment conducive to this essentially tropical creature in our homes. Dr. Miller finds it a sobering truth that house dust mites probably didn’t exist in our air leaky homes in the USA and Canada in the 1950s and now they are ubiquitous. There are two main species of dust mites. The primary difference is that one species prefers a slightly warmer temperature. The species can cohabitate and are often found together. Dust mites eat skin cells and other bits of protein they find in beds, pillows, carpets and soft furniture.

For the first time a publication covers diagnosis and treatment with grades of evidence. In addition to medication, a substantive discussion of role of buildings and importance of avoiding exposure is included.Information probably new to most clinicians is discussed in the parameter that: RH varies within rooms and the significance of condensing surfaces. House dust is hygroscopic. Floor surfaces can become “happy valley” for dust mites. The document signals and explains to the medical community the important role of vacuuming and cleaning. There is a map of the USA& Canada with the odds of having house dust mite allergen. This information triggers discussion between doctor and patient about moisture, avoidance, and sampling locations effects resolution and outcome (Portnoy et al. 2013b).

What about mold?

He explained the mold situation by reverting back to dust mites. Dust mites were a problem, becoming a nuisance and leading through the processes of anger, denial and finally acceptance. Prior to 1988, the conventional wisdom regarding mold in buildings was that “it’s ugly and but not a major health problem”. After the energy crisis in the 1970s, government and academic researchers started working on mold and dampness. Then industrial hygienists got active, the NYC guidelines were issued due to worker exposures, followed by ASHRAE. Allergists have long been interested in the molds in outdoor and indoor air. However, the efforts of the environmental allergens workgroup on mold and dampness represent a thorough update perspective on this issue. The group worked for more than 2 years producing 5 papers which appeared in the May June issue of the JACI Practice. One paper describes changes in the taxonomy of allergenic fungi (Levetinet al. 2016).

Understanding mold and dampness has been a long journey through the various professional communities: industrial hygienists, engineers, architects and medicine. Unlike cats, rats, cockroaches and dust mites with a small number of allergens, there are hundreds of fungi that are common in damp buildings depending on the conditions. How to link the species to health effects is difficult. While health effects have been demonstrated in well done studies since 1989 in the USA, these effects appeared and are more complicated than exposure-outcomes to the other building associated allergens. With mold if you live or work in a damp moldy building you are more likely to be allergic to many things acquiring allergy to some molds, pollen, dust mites, etc. as well as increases in upper respiratory disease.

As a way to think about this, Dr. Miller went back to the health responses to cockroaches. Cockroaches make allergens which can be measured in the environment and the connection to the patient can be made. However, the epidemiology suggested that there were also non-allergic consequences. One reason for this is that when inhaled fragments of the polymer that make the insect’s exoskeleton, chitin is enzymatically broken down to small bits in the lungs of some people. Particular receptors in the lung interpret these fragments as danger signals and trigger inflammatory reactions.

Mold fragments contain allergenic proteins, maybe a couple of dozen of which have been characterized for common damp building fungi. However, fungi also contain a chitin-like polymer and mold fungi contain another polymer, beta 1, 3 D glucan. Humans also a fungal glucan receptor, we don’t know why we have it, but we do. Both glucan and the fragments of fungal ‘chitin” are seen as danger signals provoking inflammation. Finally, there are a number of fungal proteins that are similar but not identical to human proteins.

The population health, clinical and mechanistic issues are described in three papers: Baxi et al. (2016), Larenas-Linnemannet al. (2016) and Williams et al. (2016).


Dr. Miller objects to the use of this term because this is reserved for very potent compounds known to affect human and animal health in crops, food and feed. Many of the damp building fungi do produce low molecular weight compounds, but as with the allergens, the identifies of these compounds is known only for a few dozen species and most of this information is recent. These compounds do occur in fragments and dust in small absolute amounts. At present, it appears that the inflammatory factors described above explain much of the response. Based on studies in laboratory animals, low exposures do contribute to the inflammatory process. On the other hand, if after flooding a homeowner was carrying heavily fungal colonized paper or cardboard close to their body and inhaled a large dose of fungal metabolites they can get really sick and require hospitalization.

Medically relevant home inspection:

Dr. Miller felt that the two papers dealing with evidence-based questions that clinicians can ask their patients about the state of their home possibly triggering a home inspection (Chew et al. 2016) and on conducting a medically relevant home inspection were really important. Chew et al. (2016) provides a list of questions for “gold standard” home inspection that is useful and understandable by clinicians.Everyone inspecting a building with water or IEQ issues has a different reason. An inspection for insurance purposes, for industrial hygiene, for a contractor & etc. has a different emphasis. Each profession has its own jargon. Unfortunately, much of the time, most of the time, home inspections and air sampling results are neither understandable or useful to clinicians. Taking evidence from research epidemiology studies and experience over the last decade (e.g. the AIHA Green Book, ASRAE, NIOSH), Barnes et al. (2016) provide information on information that should or should not be used. An example of the level of detail needed for research epidemiology studies for home inspections is provided with comments on remediation issues.

Question from the audience:

Is IGG testing of value?

A big issue is that a negative test result doesn’t necessarily mean anything. There can be hundreds of types of fungi in a damp building. The test may be done at the wrong time, the effects triggered by another organism or exposure may have been temporary.

Links to important AAAI documents:

The parameters are all open access. http://www.allergyparameters.org/publis ... -download/
Unfortunately, at this time, the material on fungi requires a subscription. This is being looked into now. The way at present to get a copy is to email any one of the authors.

http://www.jaci-inpractice.org/issue/S2 ... %29X0003-7

Barnes CS, Horner WE, Kennedy K, Grimes C, Miller JD (2016). Home assessment and Remediation. J Allergy Clinical ImmunolPract 4:423-431

Baxi SN, Portnoy JM, Larenas-Linnemann D, Phipatanakul W; Environmental Allergens Workgroup (2016) Exposure and health effects of fungi on humans. J Allergy ClinImmunolPract 4:396-404.

Chew GL, Horner WE, Kennedy K, Grimes C, Barnes CS, Phipatanakul W, Larenas-Linnemann D, Miller JD (2016) Procedures to assist health care providers to determine when home assessments for potential mold exposure are warranted. J Allergy ClinImmunolPract 4:417-422.

Larenas-Linnemann D, Baxi S, Phipatanakul W, Portnoy JM; Environmental Allergens Workgroup (2016) Clinical evaluation and management of patients with suspected fungus sensitivity. J Allergy ClinImmunolPract 4:405-414.

Levetin E, Horner WE, Scott JA; Environmental Allergens Workgroup (2016) Taxonomy of allergenic fungi. J Allergy ClinImmunolPract 4:375-385.

Portnoy J, Sublett J, Kennedy K, Barnes C, Chew GL, Grimes C, Matsui EC, Miller JD, Miller J, Phipatanakul W, Seltzer J, Williams PB (2013a). Environmental assessment and exposure reduction of cockroaches: A practice parameter. J Allergy ClinImmunol 132:802-32.

Portnoy J, Miller J, Williams B, Chew GL, Miller JD, Zaitoun F, Phipatanakul W, Kennedy K, Barnes C, Grimes C, Larenas-Linnemann D, Sublett J, Bernstein D, Blessing-Moore J, Khan D, Lang D, Nicklas R, Oppenheimer J, Randolph C, Schuller D, Spector S, Tilles SA, Wallace D (2013b) Environmental assessment and exposure control of dust mites: a practice parameter. Ann Allergy Asthma Immunol 111:465-507.

Williams PB, Barnes CS, Portnoy JM; Environmental Allergens Workgroup. Innate and adaptive to fungal products and allergens. J Allergy ClinImmunolPract 4:386-395.

Today’s Music:
“Growing Mold” by the Radioactive Chickenheads – YouTube

Z-Man signing off

Trivia Question:

What is the common name for seasonal allergic rhinitis?

Hay fever
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