J. David Miller PhD – The New Green Book & The FACTS on Mycotoxins

Air Date: 2-7-2020|Episode 573

This week on IAQ Radio+ we welcome J. David Miller, PhD. back to IAQ Radio+ for a discussion on the newly revised AIHA Green Book “Recognition, Evaluation and Control of Indoor Mold” and an in depth discussion of mycotoxins. Dr. Miller received his secondary education at the University of New Brunswick, before studying at the University of Portsmouth in England, where he was also a NATO Science Postdoctoral Fellow. He began his post-university career at Agriculture Canada in 1982, and became head of the Fusarium mycotoxin program in 1988.

He became a Professor & NSERC Research Chair at Carleton University in 2000. From 1999-2008, he was a visiting scientist and science advisor in the air health effects section of Health Canada. His work involves the development of methods to assess exposure to determinants of respiratory health in indoor environments and on fungal toxins in food and feed. Dr. Miller has published >350 papers on fungi and fungal toxins and has co-written 10 books on the public health aspects of exposures to fungi, and has several patents. He has served on many national and international committees on mold and dampness in the built environment. He is a fellow of the American Industrial Hygiene Association.

J. David Miller, PhD- New Green Book & the Facts about Mycotoxins

Scientist, researcher, professor, advisor, author and industry volunteer; J. David Miller, PhD is an international Go-To-Guy on both fungal toxins and the assessment of determinants of respiratory health in indoor environments.

Nuggets mined from today’s episode

The new edition of the Green Book is dedicated to Phil Morey, PhD. The 3 guiding principles of the original NY City Mold Guidelines are: 1. Mold in buildings is bad. 2. The more mold the more complexity and risk. 3. After remediation including addressing the underlying moisture problem, Clean things up- thorough particle cleanup. The 3 principles remain important today.

Dr. Miller was the senior editor of the AIHA’s newly revised Green Book.  Released 12 years after the first, the second features 25%-33% new content. The key chapters have been peer reviewed and references updated. The new edition has been gone through carefully and is aligned with 2020 guidance information from other important sources. The revised book also reflects many changes in the names of the common damp building fungi.

The public health argument over wet buildings is over. AIHA and ASHRAE have revised their positions, research done by  WHO, Health Canada, NIOSH, many academic researchers as well as allergy community reflected by views of expert panels of the American Academy of Allergy Asthma and Immunology document and have come to a broad consensus about the population health impact of living or working in a building with material mold and dampness issues.

Why do fungal names change? The legalistic reason is that some fungi look like common molds. For example, if you see fungi on an orange in the US, the green color represents billions of spores of the fungus Penicillium digitatum. Molds can have a sexual phase making relatively few spores or an asexual phase with lots of spores. In some cases, the connections were hard to make. For example, the sexual phase of the really important toxigenic fungus on crops, Aspergillus flavus was only discovered in the last decade. In the mycology crowd, a fungus can only have one name. Sometimes the same fungus was discovered by more than one person and given different names.  DNA fingerprinting has corrected important mistakes.

Damp mold epidemiology. The thought that “mold is ugly and not a health threat” has changed due in part to pioneering research work done in the UK, Health Canada and Harvard University in the late 1980s and early 1990s. Since then many studies on different populations at different times have allowed important conclusions to be drawn. When dampness and visible mold is present along with health complaints, both an informed inspection and consideration of objective health measures are needed. Moisture in buildings is responsible for 20% of all asthma in the US and Canada. This has increased in part because of unintended consequences of tightening buildings after the first energy crisis in the 1970s, a shift from mold resistant to mold susceptible building materials as well as the large change in the prevalence of AC in houses not really designed for this.

Joe asked why after all these years, there remain no simple sampling measures that can replace an informed and properly documented inspection.Two important reasons emerged. One is that personal exposure in buildings is a function of visible mold but also the burdens of fungal particles in settled dust. The only really good way to sample this is to use a device that takes air from near the breathing zone. When you walk, run, jump or dance across the floor, the particles surround you as seen in around Pig Pen in the Charlie Brown cartoon.

Nonetheless, the sampling procedures described in the Green Book and the second edition of the AIHA Field Guide properly done help investigators assess whether there is hidden mold. Sampling should never be done absent an informed inspection. The sampling procedures in the Green Book are aligned with guidance from allergy physicians on their needs if a home inspection is thought useful for patient management. However, Dr. Miller says sometimes it’s hard to read the tea leaves. For example, air sampling did not initially reveal that complaints in a large building were due when fibrous insulation inside the ductwork became a mold factory.  This took sampling on the diffusers and settled dust. Another example was a flooded building that was improperly remediated. Five years after the flood after people started to complain, the fungal spores and fragments from the wall cavity when the room was negative to the envelope were detected by sampling and physical remediation revealed very large areas of mold that was not culturable and developed a latent mold problem.

Joe asked why it took so long for people to agree that mold and dampness in a building was bad for health. Aside from the sampling issue mentioned above, one really important problem was that while increased asthma symptoms in mold sensitive asthmatics seemed reasonable (molds including those outdoors cause/ make allergens), higher rates of asthma in general and upper respiratory disease could not be explained. Dr. Miller noted that in epidemiology, one is always mindful of the good correlation between the number of storks and the number of babies. It took a couple of decades and a lot of money to obtain a meaningful understanding of the mechanisms involved.

What about hidden mold and mold odor?The human nose knows to avoid mold. The human nose is more sensitive than a mass spec. Sampling for mold volatiles is sometimes used to determine if mold is growing in large grain silos.

Dr. Miller talked about samples taken in large research studies which typically involve carefully sampling settled dust to get loading. Dust mites, rodent allergens, endotoxins and for fungi, properly measured mold glucan.  This is a more or less quantitative measure of fungi in the building but exposure is one of the most important biochemicals that gives mold its unusual impact on health. Mold glucan activates a human receptor called Dectin-1. This along with a number of other compounds in mold fragments (chitin fragments, fungal enzymes and proteins that are rather too similar to human proteins) are given the name “danger associated molecular patterns”, Again, all this took decades of research to get to where we are today,

Joe wanted to ask about mycotoxins.

The term mycotoxin was coined in Russia in the late 1950s and came into wide use by the mid 1960s. Mycotoxins are produced by some molds as the term is used today it strictly means compounds that are KNOWN to affect human or animal health. There are only five agriculturally important mycotoxins on a worldwide basis and a number of less common compounds that seldom cause problems. They can cause billions of dollars of damage in bad crop years. This really matters to the US and Canadian economy with damage in the billions in bad years. Mycotoxins are never volatile. They are always associated with fungal particles, spores and damaged food or building materials.

Dr. Miller noted that the Green Book has a section on the compounds produced by the fungi from damp building materials, none of which are agriculturally important compounds. It discusses commentary from the US CDC in an HHE and from leading academic experts in Europe on fact that methods that claim to be detecting ‘mycotoxins’ in urine. He mentioned a recent inquiry from a US physician about a patent who was told that ochratoxin A in the urine was harmful and came from mold in the building. The problem is that none of the fungi that produce ochratoxin A grow on building materials in the real world. However, some ochratoxin A is found in wheat and oats in some years in the US, something that the US FDA monitors very carefully.

It is really hard to reliably measure fungal metabolites in urine or serum and only a few labs in the world can do this reliably. The labs need special standards, most of which have to be chemically synthesized.

As with all other compounds associated with fungal fragments, any low molecular weight compounds present are removed by thorough particulate cleaning.

Joe asked if there are any chemicals that destroy low molecular weight fungal compounds including mycotoxins. Dr. Miller again reflected that mycotoxins in food are a big economic problem and in some developing countries large numbers of people are sickened. If there were legal ways to destroy mycotoxins without damaging the crop, we would. People have been trying to do this for decades. He observed that as with the Senate building affected by anthrax, one could flood the building with chorine gas which would destroy everything, including many building systems.

Interactions? Burden from wet firewood, house dust mites, endotoxins, and traffic pollutants which weakly interact with endotoxin and allergens.

Final Comment:

There is enough valuable new information in the Green Book to justify purchase.

Z-Man signing off

Trivia Question:

Name the family of highly toxic mycotoxins produced by Aspergillus flavus and Aspergillus parasiticus which grow in soil, decaying vegetation, hay and grains?



Answered by:

Michael Capalbo, CSP

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