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Mold Odor from Wood Treated with Chlorophenols despite Mold Growth That Can Only Be Seen Using a Microscope
Johnny C Lorentzen1,2, Olle Ekberg3, Maria Alm4
1Integrative Toxicology, Institute of Environmental Medicine, Karolinska Institutet, SE-171 77 Stockholm, Sweden.
Microorganisms
|February 24, 2024
Summary
Microscopic mold on chlorophenol-treated wood causes indoor odors, not just hazardous mold. This finding suggests chlorophenols, not mold, may explain health effects linked to mold odor in studies.
Area of Science:
- Environmental Science
- Microbiology
- Building Science
Background:
- Indoor odors linked to chloroanisoles (CAs) are emitted from microbial methylation of chlorophenols (CPs) in wood preservatives.
- Previous research suggested hazardous mold causes these odors, a phenomenon noted since the 1970s.
Purpose of the Study:
- To investigate the presence of mold on CP-treated wood.
- To determine if mold presence correlates with perceived odor.
- To clarify the source of indoor malodor and its relation to health effects.
Main Methods:
- Examined wood samples from two 1960s schools with crawlspace odors.
- Assessed for visible mold and used microscopy to detect mold growth on samples containing CPs and CAs.
- Correlated detected mold levels with perceived odor intensity.
Main Results:
- No visible mold was found in crawlspaces or on wood surfaces.
- Microscopic mold growth was detected on all tested wood samples containing CPs and CAs.
- Odor intensity correlated significantly with the amount of microscopic mold detected.
Conclusions:
- Superficial, microscopic mold on treated wood is sufficient to produce the characteristic odor.
- Chlorophenols (CPs), rather than mold itself, may be the primary cause of reported health effects.
- Epidemiological studies using mold odor as an exposure indicator may misattribute health impacts.
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