Why is there to this day still a fuss about “toxic mold,” despite science indicating it’s not a real issue?  Recently, I’ve had several calls asking me if I can test for mold toxins.  On top of that, a recent client of mine insisted that her house was filled with “mold poisons” despite that her sample results were well within the normal range.  Some of these clients come armed with blood tests showing that they have “unacceptable” levels of mold toxins in their blood.   Is this a real thing?

 To be clear, when I am talking about mold toxins (also known as “mycotoxins”), I’m specifically addressing potential systemic toxicity from mold toxins entering the body.  It may seem that I am splitting hairs and being a bit of a mold technical wonk, but in my world – especially in legal matters – it’s an important distinction. 

The topic of mold toxins should not be confused with what medical science definitively accepts about mold health hazards.  There is no debate that mold can cause a variety of respiratory problems (allergies, asthma, hypersensitivity pneumonitis), occasionally skin issues (rashes), and very rarely, infections.  We also know that wet, actively growing mold emits volatile organic compounds that can be very irritating to the respiratory system.  However, these health effects have nothing to do with mycotoxins.  Pretty much  any mold species in elevated amounts can be a respiratory hazard.  Of course, mold is a significant property detriment and potentially a major source of liability for landlords, property managers, realtors, and property sellers.  So regardless if mold toxins themselves are a “real” hazard or not, never think that mold isn’t a real problem – it most definitely is.  At the end of the day, all mold problems should be remedied; the kind of mold matters little.

Back to mold toxins.  It’s well documented that some molds create toxins as they grow.  We also know that if you consume the toxins in very high amounts, it can be a serious health risk. There are actual case histories (i.e., real science) of people and livestock eating moldy food and getting sick and/or dying.  However, some mold toxins (like the antibiotics Penicillin and Erythromycin) are helpful to mankind.  But both of these situations (harmful and beneficial) involve directly consuming a very large amount of the toxins. 

Now here’s a crash course on toxicology.  Science knows very well that the human body is pretty good, up to a point, at detoxifying chemicals.  In order to experience a toxic effect for any given chemical, you have to reach a dose threshold.  After you reach that threshold, the harmful effects of toxins get worse rather quickly.  For instance, if I take a sip of Chardonnay, I don’t experience any effects from ethanol.  However if I drink a glass, I’ll feel it (I’m a cheap date).  If I keep drinking, I get progressively more intoxicated, because my dose of ethanol has increased.  If I drink enough, I could die of alcohol poisoning.  Based on this known toxicological progression, we know that the human body does not have “zero tolerance” to toxins (i.e. the harmless sip of Chardonnay).  Furthermore, there are low levels of both naturally occurring and man-made toxins all around us (especially in urban environments) that don’t cause problems.

Regarding mold toxins, repeated published studies have shown that when people are exposed to moldy indoor air, the exposure to toxins is very minute, and not enough to cause any health effects.   People just don’t get enough of a dose of the toxins to have a health impact (but don’t forget that mold is still potentially a health hazard, as I discussed above – we’re just talking about the toxins here).  Furthermore, as there is a little mold toxin naturally occurring in the food supply, we all get exposed to them a bit.  Pretty much everyone will have a little mold toxin showing up in a blood test.  Some foods – such as peanuts and peanut butter – can have significant toxin levels.  The value of the blood test is debatable at the levels that some labs are telling people are a problem.

Meanwhile, some people – typically doctors of dubious quality and mold industry types with little formal education – claim that toxins from mold problems indoors are a serious health threat.  Their paradigm typically claims that even one spore of a “toxic” species of mold (such as Stachybotrys – the “toxic black mold”) is enough to make some people ill.  A doctor on the east coast – who is famous for his books, seminars, and web site about mold dangers – claims that up to 25 percent of the population has a genetic flaw that makes them have zero tolerance to mold toxins – supposedly even one spore is a health threat.  However, this is not a scientifically accepted theory, and has not been backed up by published peer-reviewed studies.  This also makes no sense since all spores, including the Stachybotrys and other toxic species, are present outdoors and have been there for millions of years, so all of earth’s population is exposed.  The particular doctor lost his license to practice medicine based on a number of shady practices.  However, he continues to preach the “dangers” of mold toxins, and has developed his own little cottage industry which he profits from.  Those that don’t agree with the “toxic mold” paradigm are portrayed as part of some kind of conspiracy. 

 Just how would inhalation exposure to mold toxins occur, if someone had a mold problem?  The mold toxins are not volatile (i.e. evaporate) and as such don’t get airborne on their own.  Primarily, the toxins get inhaled by hitching a ride on mold spores and the other fragments of mold that can break loose and become airborne.  But this happens on a very small scale.  Reputable studies have repeatedly shown you’d have to get an incredibly huge exposure to the mold spores – think multi-millions of spores – in order to absorb enough of the toxins into your
body to even notice it.  Ironically, Stachybotrys spores don’t get airborne very well due to their size and sticky surface, so we rarely see hundreds of it in the air…and certainly never millions!  Also, there is no real database of peer-reviewed studies verifying that cases of mold poisoning exist from airborne exposure (except in agricultural jobs).  If this was real issue – and 25 percent of the population was allegedly susceptible to it – wouldn’t we have some good epidemiology (i.e., case histories)?  And yet, we don’t.

Nonetheless, claims continue by some mold practitioners, some doctors, “victims,” and the media that “toxic mold” is harming people, and at levels that are equal or near to background.

From my own perspective, having spent over 35 years in environmental health and safety, I’ve occasionally had to deal with some highly toxic materials.  Back in the days when I worked in industry, I encountered some super nasty toxic compounds, such as hydrazine, silane, arsine, hydrogen cyanide (aka death chamber gas), and more.   It rattles my brain to hear that some people persist in thinking that essentially background level amounts of mold toxins are worse than the most toxic industrial chemicals, despite the lack of actual scientific evidence or epidemiology.  When one considers the actual dosage amount to mold toxins (for instance, nano- or pico- grams)  vs. the established safety limits of the highly toxic industrial chemicals (milli- or micrograms), it’s hard to swallow the allegations about mold toxins.  In addition, what peer-reviewed studies are out there don’t seem to support the claims that toxins from moldy indoor environments is a real issue.

As mentioned above, all mold species – toxic or not – can be a big problem for occupants, building owners, and building managers, and a health  threat nonetheless regardless of the “toxic” issue.  If that’s true, why does the debate over whether mold toxins matter?  Because it is fearmongering.  Because there are unethical mold consultants who charge huge fees to test for toxins.  Because the public still hears and reads about  the “dangers of toxic mold,” causing undue worry.  And because some attorneys, who don’t know any better, still try to make lawsuits over it.

To recap, here’s some established facts on mold:

  • Mold has been on the planet for millions of years, and predates human life.
  • All mold is natural and comes from background air; even the “toxic” species show up in outdoor samples.
  • People used to live in worse habitats than we do now, and mold has obviously been around a long time, but it was not really much on the radar as a health issue until the late 90’s.
  • Some molds are well known to generate toxins as they grow, but they don’t get airborne hardly at all.  The biggest hazard is from ingesting (i.e., eating) moldy foods.
  • If mold toxins are really that pervasively bad, then how come there is not a wealth of epidemiology and studies proving it, especially considering how long mold has been around?
  • Reliable, peer reviewed research continues to show that you’d have to have an incredibly massive exposure to mold to get enough mold toxins in your body to notice a health effect.