Moldy Window Sill

Unless you’ve been living under a musty rock, you’re likely familiar with the devastating health effects of mold exposure.  By now, most people know that mold can be toxic and even deadly, and will take action if they see it cropping up on the bathroom tile.

But did you know that most mold problems are hidden mold problems?  Or that even if you cannot see or smell mold, it can harm your family just the same?

In this article, I’ll explain exactly what toxic mold is, why our homes are more susceptible than ever, and how to protect your family.

Everything You Need to Know About Toxic Mold


Mold 101 Table of Contents


What is Mold, Exactly?

Molds are a type of microscopic fungi which, outside of sterile environments, are completely unavoidable.  In fact, fungi are so ubiquitous that it is estimated that they make up some 25% of the Earth’s biomass!

In case it’s been a while since high school biology, fungi are plant-like organisms that fall into three categories: yeasts, molds, and mushrooms.  Yeasts are single-celled organisms while mushrooms have large fruiting bodies. Molds, by contrast, have a filamentous (hyphal) growth pattern, and large colonies often appear fuzzy or powdery.

I promise the science lesson is almost over, but it’s important to understand the reproductive cycle of molds.  The reproductive units of molds (and other fungi) are called spores. You can think of spores as fungal seeds.*

Take these mold spores, add a bit of moisture, a food source, and a cozy temperature, and you’ve got the perfect recipe for mold proliferation.

*PSA for my science fundamentalists who are cringing right now: Yes, I know that spores are not technically seeds. I also know that 95% of my audience understands the role of a seed in a plant’s life cycle and care not about the details of reproductive biology.  


Mold is Everywhere, Y’all!

So I mentioned that molds and fungi are ubiquitous already, but gimme a sec to hammer this home.  The reason mold is everywhere is because it serves an important function. Mold acts as nature’s decomposer, breaking down and recycling organic matter such as leaves, wood, and food.  And the way that it does it is really kinda crazy.

Mushroom on Forest Floor

As I explained to my 7-year-old recently, essentially mold barfs up digestive enzymes which melt (metabolize) the thing it’s on (substrate), then it absorbs (via osmotrophy) that sugary goo for food.  Yummy.

But there’s more to fungi than decomposing the things around us. Humans have been harnessing the nutritional, medicinal, metabolic, and psychedelic power of fungi for a long time.  We eat them (mushrooms and blue cheese), ferment with them (hello my fellow kombucha lovers!), use them as medicine (such as antibiotics), use them extensively in agriculture, and let’s not forget our rich history with “magic” mushrooms.

So basically fungi can be beneficial, can be detrimental, and are impossible to avoid. If mold was on Facebook, we’d have to set our relationship status to “It’s complicated.”

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By the way, mold and mycotoxin contaminants in our food supply are a MAJOR problem, and one you should be very aware of.  However, the scope of this article will not address the horrors of the standard American diet and how it is slowly but surely killing you.  For that, let me direct you to the brilliant work of professional biohacker, Dave Asprey, or expert mold-avoider, Doug Kaufmann.


What is “Toxic Mold?”

Though the term is a bit of a misnomer, toxic mold really is as terrible as it sounds.  You see, the mold itself is not toxic (though it can be highly allergenic and cause other problems).  Instead, as a protective mechanism, some fungi produce harmful chemicals known as mycotoxins.  When a mold produces these mycotoxins, it is considered a toxic mold.

Mold spores will cause some trouble, but mycotoxins are like a bullet with molds as the gun. Mycotoxins are much worse.



Mold, Mycotoxins, and Human Health

To be clear, fungus itself can and does cause disease in humans (everything from athlete’s foot to aspergillosis).  But much more commonly, humans fall prey to the ill effects of a fungus’ poisonous secondary metabolites (mycotoxins).  Mycotoxins are pharmacologically active and can cause disease and death in humans.

To put it simply: Mold can make you sick, fat, fatigued, stressed, chronically ill, brain foggy (not a term, but certainly should be), and can eventually kill you.

Some common symptoms include cognitive issues (such as impaired memory and learning, confusion, and difficulty concentrating), respiratory problems, fatigue, weakness, aches, disorientation, mood swings, skin sensitivity, tremors, sensitivity to light, excessive thirst, and more. Mold-related illnesses are often misdiagnosed as chronic fatigue syndrome, fibromyalgia, irritable bowel syndrome, and depression, among others.

Sick Person on Couch

I believe that the role of mold and mycotoxins in many chronic health conditions is grossly underestimated by the mainstream medical community.

One major reason for the confusion is because mold affects every person differently.  Even people living in the same mold-contaminated home may experience vastly different symptomology, with some people in the home even seeming completely unaffected.

A 2003 article in Clinical Microbiology Review explains in detail the complex relationship between mycotoxins and human health.  The authors explain that “the severity of mycotoxin poisoning can be compounded by factors such as vitamin deficiency, caloric deprivation, alcohol abuse, and infectious disease status. In turn, mycotoxicoses can heighten vulnerability to microbial diseases, worsen the effects of malnutrition, and interact synergistically with other toxins.”


Why Today’s Homes are More Susceptible to Mold

The presence of mold in homes is certainly not new.  In fact, there are instructions on how to handle “defiling” mold and mildew in the bible (book of Leviticus).

But even over the last 20 years, there has been a significant increase in the number of mold-contaminated homes.  Why is this?

Homes have gotten tighter and have poor ventilation

As energy conservation has become more important, our homes have gotten “tighter,” reducing the amount of conditioned air leaving the home.  While this has had a positive impact on our energy bills, it has come at a cost.

In theory, a tight home is a fantastic idea, but in practice a different story emerges.  Design flaws, inadequate ventilation, and a general lack of systems thinking has created a new set of problems in our homes, including:

  • Poor indoor air quality
  • Backdrafting of carbon monoxide and other combustion gases
  • Uncontrollable humidity and mold proliferation


Homes are made from refined mold food sources

We used to build homes with stone, dirt, brick, and hard timbers (which naturally contain antifungal resins).  But just as our food supply has gotten cheap, highly refined, and detrimental for human health, so too has our housing stock.

Cheap man-made timbers such as plywood and particle board have been refined so as to make the sugars more accessible to molds.


Homes are unable to dry properly

Rain Running off of a RoofA mold problem is really a moisture problem.  In addition to leaking from the exterior, we are constantly producing moisture inside our homes.  Everything from cooking and showering to simply breathing introduces moisture into the home.

In traditional homes (such as those made from adobe) this was no problem because they had an incredible drying potential.

By contrast, modern houses have plastic vapor barriers, thick insulation, synthetic seals and paints, as well as floor and wall coverings with low permeability.  These all contribute to moisture getting trapped inside faster than the home can dry itself out.


How to Prevent Toxic Mold in Your Home

In part 2 of this series, you’ll learn the Best Mold Avoidance Strategies.


The Best Ways to Test Your Home for Toxic Mold

In Part 3 of this mold 101 series, we discuss the most effective (and inexpensive!) ways of testing your home for toxic mold growth.  (Hint: The highly-praised ERMI test is NOT a test that I recommend often!).  Hope to see you there!


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