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Demystifying mold: understanding the basics

In the quiet corners of our homes and offices, a silent and often misunderstood intruder lurks – mold. While it may seem like a simple nuisance, understanding what mold is and how it operates is crucial for maintaining a healthy living environment.


At its core, mold is a type of fungus that grows in multicellular fiber-liked structures called hyphae. Mold reproduces by releasing tiny spores into the air, which can settle on surfaces and grow into new colonies when the conditions are right. Spores also give a mold color and contain fungal secondary metabolites. The most know are mold toxin known as mycotoxin (Moore et al., 2011).


Mold has been around for millions of years. Unlike plants, molds do not produce their own food through photosynthesis. Instead, they rely on external sources of organic material for sustenance. In nature, mold is an important part of the ecosystem as it helps to break down organic matter, such as dead leaves.

There are thousands of mold species, each with its unique characteristics, that are completely harmless. Some molds are used to produce food items such as soy sauce and cheese, as well as medicines such as penicillin. However, other species can pose health risks and cause damage to buildings and materials.


Over 300 mold species produce biotoxins that are harmful and even deadly to humans and animals. Common indoor toxic mold species include (Bush, Portnoy 2001):

  • Alternaria

  • Aspergillus

  • Cladosporium

  • Penicillium

  • Fusarium

  • Mucor

  • Rhizopus

  • Stachybotrys

  • Gibberella

  • Bipolaris

  • Chaetomium

  • Monascus

  • Trichothecium

  • Cephalosporium

  • Petromyces

  • Neopetromyces

They are mostly found inside buildings. These toxic molds produce and release mycotoxins which function as a self-protective mechanism against microbial competitors and animal predators (Künzler, 2018). When the toxic mold is disturbed or threatened, it releases mycotoxins to defend and spores to further propagate. The most common mycotoxins include:

  • Aflatoxins

  • Citrinin

  • Enniatin B

  • Fumonisins

  • Gliotoxin

  • Mycophenolic acid

  • Ochratoxin A

  • Patulin

  • Satratoxin G

  • T-2 toxin

  • Zearalenone.

These mycotoxins are poisons in the same arena as, or worse than, toxins like arsenic, lead, mercury, asbestos, tobacco, pesticides, herbicides, PCBs, formaldehyde, dioxins and more. Some are even used for biological warfare.


Toxic mold possess health risks when inhaled, ingested or come into contact with he skin. Exposure to mold spores may cause respiratory issues, nasal congestion, skin and eyes irritation. Beyond the immediate discomfort cause by mold exposure, it is crucial to recognize the long-term adverse effects to many organ systems. Mycotoxins and other organic chemical compounds produced by mold are responsible for various toxicologic effects to the respiratory, immune, nervous, and endocrine systems, liver and kidneys. They also may cause DNA damage and developmental problems (Bennett and Klich, 2003; Gray et al., 2003; Richard, 2007; Empting, 2009; Kritas et al., 2018; Ratnaseelan et al., 2018; Hyvönen et al., 2020a; Hyvönen et al., 2020b; Lieberman and Curtis, 2020). Prolonged exposure to certain types of mold has been linked to chronic conditions such: 

  • asthma and other lung diseases

  • autoimmune diseases

  • cancer

  • Mast Cell Activation Syndrome (MCAS)

  • Multiple Chemical Sensitivity (MCS)

  • neurological disorders: autism, chronic fatigue syndrome (CFS), dysautonomia, fibromyalgia, POTS, dementia, balance and coordination problems

  • psychiatric conditions: anxiety, depression, OCD.


Mold can also exacerbate existing health issues, making it a serious concern that demands attention. Recognizing the signs of mold-related health issues is crucial for early intervention.


Beyond its impact on human health, mold can also contribute to structural damage in buildings and homes. It can compromise the integrity of materials, leading to costly repairs. Understanding the environmental consequences of mold emphasizes the importance of proactive measures to mitigate its growth.


Understanding the conditions that foster mold growth is essential for effective prevention. Mold requires moisture, warmth, and an organic food source to thrive. In houses mold can usually be found in damp, dark or steamy areas such as bathrooms, kitchens, storage space, basement, plumbing spaces, and areas with poor ventilation. Leaky roofs, plumbing issues, or high humidity levels can create ideal environments for mold to flourish.

The problem is that mold can survive in the building undetected. It can hide beside the walls and floor. Mold does not always give off an odor, especially when it is trapped behind the building material. It can hide in moisture places and wait for the good condition so it can start growing again. It needs excess humidity to grow, and visible water is not required. 

Indoor mold decomposes carbohydrate-rich material such as carpet, wood, cork, drywall and even cement. Modern building materials contain a lot of toxic chemicals which mold uses as the source of energy. Also increased electromagnetic smog helps the mold to not only grow, but also produce more toxins (Klinghardt, 2012).


Regular inspection and prompt addressing of water-related problems are key to preventing mold infestations. Simple measures such as regular cleaning, proper ventilation, maintaining optimal indoor humidity levels (30-50%), using an air conditioner or a dehumidifier during humid months, and addressing water leaks promptly can significantly reduce the risk of mold development. In case of flooding, it is crucial to clean up and dry out home thoroughly and quickly as mold can start growing within 24-48 hours. 

If mold is already present, professional remediation is necessary to ensure thorough removal and prevent recurrence. Even after the mold is removed, the threat of mycotoxin exposure remains unless the spores and mycotoxins are removed from the environment.


In essence, mold is a natural part of our environment, but when it infiltrates our living spaces, it can become a health concern and a threat to our surroundings. By understanding what mold is, recognizing its favored conditions, and taking proactive steps to prevent and address its growth, we can create healthier, safer environments for ourselves and our families. Mold may be a hidden adversary, but with knowledge and awareness, we can unveil its intricacies and take control of our living spaces.



Behrens M, Hüwel S, Galla HJ, Humpf HU. (2015). Blood-brain barrier effects of the Fusarium mycotoxins deoxynivalenol, 3 acetyldeoxynivalenol, and moniliformin and their transfer to the brain. PLoS One. 10(11):e0143640.

Bennett JW, Klich M. (2003). Mycotoxins. Clinical Microbiology Reviews. 16(3):497–516.

Bush R, Portnoy J (2001). The role and abatement of fungal allergens in allergic diseases. J Allergy Clin Immunol.107: 430-40.

Empting LD. (2009). Neurologic and neuropsychiatric syndrome features of mold and mycotoxin exposure. Toxicol Ind Health. 25(9-10):577-581.

Gray MR, et al. (2003). Mixed mold mycotoxicosis: immunological changes in humans following exposure in water-damaged buildings. Arch Environ Health. 58(7):410-420.

Hyvönen S, Lohi J, Tuuminen T. (2020). Moist and mold exposure is associated with high prevalence of neurological symptoms and MCS in a Finnish hospital workers cohort. Saf Health Work. 11(2):173-177.

Lieberman A, Curtis L. (2020). Mold wxposure and mitochondrial antibodies. Altern Ther Health Med. 26(6):44-47.

Moore D, Robson GD, Trinci AP, eds. (2011). 21st Century Guidebook to Fungi (1st ed.). Cambridge University Press. ISBN 978-052118695.

Klinghardt D. (2012). Advancing Medicine with Food and Nutrients. (2nd edn). In: Ingrid Kohlstadt (Ed) CRC Press, Boca Raton, Florida.

Kritas SK, et al. (2018). Impact of mold on mast cell-cytokine immune response. J Biol Regul Homeost Agents. 32(4):763-768.

Künzler M. (2018). How fungi defend themselves against microbial competitors and animal predators. PLoS Pathog. 14(9):e1007184.

Ratnaseelan AM, Tsilioni I, Theoharides TC. (2018). Effects of mycotoxins on neuropsychiatric symptoms and immune processes. Clin Ther. 40(6):903-917.

Richard JL. (2007). Some major mycotoxins and their mycotoxicoses – an overview. Int. J. Food Microbiol. 119(1–2):3–10.

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