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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
PubMed

Insights

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.
Keywords:
allergyasthmaconfoundingdampnessindoor airmoldodorpesticidessick building syndromewood preservatives

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