The Truth About Mold Toxicity

We’ve all heard horror stories of toxic black slime oozing in dank corners of basements, causing life-threatening conditions in children, and strickening parents with mysterious neurological symptoms that baffle doctors.

It’s all scary stuff, but is there any truth to these rumors?

Here we’re going to separate the fact from the fiction when it comes to mold toxicity. But before we do that, let’s get a little more familiar with what mold is exactly.

Black mold on ceiling

Household Mold 101

We go into great depth on this topic in our guide to the most common types of household mold, but here are the key takeaways.

First, mold is everywhere.1 Mold is an important employee in nature’s cleanup crew. It exists whenever organic matter and moisture convene, and for good reason. If it weren’t for mold breaking down natural detritus, we’d be up to our necks in dead material. The bad news is that mold and human respiratory systems do not play well with one another, but we’ll get to that in a minute.

The next thing to know is that there are three types of mold:

• Allergenic molds
• Pathogenic molds
• Toxigenic molds

As the names imply, their threat levels increase as we go down the list, but thankfully, how common they are — particularly in our homes — decreases.

Allergenic and pathogenic molds are relatively common, and depending on your sensitivities, exposure to them might cause mild to moderate symptoms. It’s that last one — toxigenic molds — that brings us here today.

What Do We Mean by “Toxic” Mold

The term “toxic mold” is a bit of a misnomer, which has led to misunderstandings about how dangerous it actually is. So let’s dispel one myth right now: All molds, if present in high enough concentrations, can cause health complications.3 It’s not just the “toxic” ones.

Is mold categorically dangerous, or are the threats overblown?

Toxic molds are called such because under certain conditions they are capable of producing compounds known as mycotoxins — metabolites that can be harmful or fatal if inhaled, absorbed through the skin, or consumed. To date, about 400 mycotoxins have been identified.4

As far as your family is concerned, there are two types of toxic mold that your family needs to be aware of.5

• Aspergillus: This is a common household mold, but there are a few particular strands that are toxigenic; namely, A. versicolor, A. niger, and A. flavus.6 The aspergillus mycotoxins are relatively benign, although symptoms of exposure can become severe in certain individuals.
• Stachybotrys chartarum: Also known as the infamous “black mold,” S. chartarum is a greenish-black mold that commonly occurs in buildings with severe water damage. Similar to aspergillus, though, studies show only a few strands can produce mycotoxins, meaning that its overall threat level is actually quite low.

So the long and short of it is this: “Toxic” mold is a scientific term that relates to a particular fungus’ ability to produce a specific compound. While those compounds can be dangerous, “toxic” is not meant to describe that mold’s overall threat level.

But that begs the question: Is mold categorically dangerous, or are the threats overblown?

Is Mold Dangerous?

We’re going to get to the details in a second, but the short answer is this: It can be. Just how dangerous it is, though, is far more a factor of your or your loved one’s particular sensitivity to mold (more on that in our guide to mold allergies), the scale of the contamination, and the duration of exposure than it is the type of mold you’re dealing with.

Simply put, the more mold spores there are in an environment, the more dangerous it will be for the health of individuals working or living in that environment. And the longer those people are exposed to high concentrations of particulate matter from mold, the more opportunities there are for negative health outcomes to occur.

With that in mind, it’s also important to understand there are populations that are more at risk than others. Young children — whose lungs are still developing — are more at risk of developing symptoms from mold exposure than their parents. The elderly and infirm are also more vulnerable. Those with chronic respiratory conditions or those recovering from ailments like lung cancer should also be particularly cautious of moldy environments.

Here’s another way to think about it: A few years back, the National Institute of Medicine put out one of the most comprehensive reports on indoor mold exposure to date, titled “Damp Indoor Spaces and Health.” Here’s one of the key findings:

“​​Scientific evidence links mold … in homes and buildings to asthma symptoms in some people with the chronic disorder, as well as to coughing, wheezing, and upper respiratory tract symptoms in otherwise healthy people… However, the available evidence does not support an association between … mold and the wide range of other health complaints that have been ascribed.”7

More simply put, mold is about as dangerous as any other common environmental contaminant, like dust or pollen. For people with severe asthma, it can be a major issue; for others, not so much. And there’s no reason to think mold is the reason you’re feeling sluggish or forgetful.

So if the threat of mold is largely overblown, where did all this hype about toxic mold come from?

The Truth About Toxic Mold Syndrome

Let’s put another myth to rest: Scientifically speaking, there is no such thing as “toxic mold syndrome.” That’s a term devised by the media to captivate (and terrify) viewers back in the ’90s, and the angst has persisted to this day thanks to internet fear-mongering and snake oil salesmen.8

There is currently no evidence toxic molds — or any molds, for that matter — cause neurological symptoms like fatigue, memory loss, headaches, or brain fog.9 And there’s certainly no evidence that normal, day-to-day mold exposure alone can cause otherwise healthy people to drop dead or develop a life-threatening illness. With that in mind, though, studies are ongoing to better understand the complex relationship between humans and environmental mold.

That said, there is something called sick building syndrome (SBS) that is recognized by doctors and scientists. This is used to describe a situation where a person develops acute negative health effects and general discomfort that appear to be linked to time spent in a building, although no specific illness can be identified.

Mold Type Cladosporium spp

Mold can play a part in SBS, but it can also be caused by myriad other environmental factors, including pesticides, car exhaust, improper ventilation, carpet adhesives, cleaning agents, carbon monoxide, and unvented stoves.10 Obviously, SBS is difficult to diagnose, and even more difficult to treat beyond medicating for specific symptoms.

So now let’s talk about what you should do if you discover mold growing in your home.

What Should I Do If I Find Mold in My House?

First of all, don’t panic. While we understand you’re worried about the health and safety of your family, like we said above, unless your loved ones are immunocompromised or otherwise vulnerable, limited exposure to small mold contamination areas is likely no big deal. You can just clean up the mold and move on with your life.

Now, with that said, you don’t want to create a bigger problem for yourself by spreading the mold around or exposing yourself unnecessarily. Before you clean up mold, make sure you’re wearing long pants, long sleeves, goggles, a mask, and gloves. Clean surfaces with diluted bleach or a commercial mold cleaner, and discard any materials that have been contaminated.

Also keep in mind that mold can grow in places you’re not seeing, like behind your wallpaper or underneath your carpets. If your mold problem persists, or if the contamination area is large, you might need to call in the pros. Lucky for you, we have a guide on how to vet mold remediation specialists.

So there you have it. That’s all you need to know about so-called “toxic” mold. Not as scary as you thought, right? Before we wrap up, though, we have some final thoughts for you.

Final Thoughts on Toxic Mold

The takeaway is this: Concerns about toxic mold are largely overblown, and finding mold in your home is no reason to break out in a cold sweat. However, moldy environments aren’t healthy by any means, so you should make efforts to prevent mold from contaminating your domestic spaces, especially if you have young children, care for elderly family members, or have loved ones that are immunocompromised.

Hopefully that helps you rest a little easier, and will help you take a reasonable, measured response to your family’s inevitable interactions with mold. If you want to learn more, we have an exhaustive resource — everything you need to know about household mold — that can help you really wrap your head around this issue.

Toxic Mold FAQs