Understanding Mycotoxins: What Scientists Know About Toxic Mold Compounds and Exposure Risks

Mycotoxins are secondary metabolites produced by certain mold species under specific environmental conditions. They are chemically diverse, biologically active, and extraordinarily stable in indoor environments. While the word “mold” often evokes concerns about spores and allergens, mycotoxins represent a fundamentally different class of risk—one rooted in molecular toxicology rather than simple microbial presence.

Different mold genera produce distinct families of mycotoxins. Aspergillus species generate aflatoxins and ochratoxin A, compounds extensively studied for their carcinogenic and nephrotoxic properties. Stachybotrys chartarum produces trichothecenes, a group of sesquiterpenes known for their ability to inhibit protein synthesis and cause inflammatory responses in mammals. Penicillium species contribute other mycotoxins, though their indoor significance varies. Importantly, mycotoxin production is not constant; even highly toxigenic strains do not generate toxins unless environmental conditions—water activity, substrate composition, temperature, and microbial competition—favor their biosynthesis.

Mycotoxins differ from spores in one critical way: they are not living organisms. They are chemical residues that can persist long after mold growth ceases. They bind to dust, settle onto porous materials, and resist degradation by environmental fluctuations. This persistence makes remediation challenging, as removing visible mold does not guarantee removal of mycotoxin contamination.

Human exposure pathways include inhalation of dust carrying mycotoxins, ingestion of contaminated particles, and dermal contact in environments with high dust loading. Toxicological studies show that exposure effects depend on concentration, duration, and individual susceptibility. In indoor settings, exposure is typically chronic and low-level rather than acute, which complicates scientific assessment and public health guidance. Nonetheless, research consistently demonstrates that mycotoxins contribute to inflammatory responses, respiratory irritation, and immunomodulation.

Testing for mycotoxins requires specialized laboratory methods such as ELISA, HPLC, or LC-MS/MS. These tests detect chemical signatures rather than biological material and must be interpreted in the context of overall indoor environmental conditions. Because these analyses are expensive, most homeowners begin with screening assessments, such as the Detekt Home mold test kit, for mold growth and moisture sources before evaluating chemical residues.

By Ryan N., PhD