Can repeated work in damp or mold-contaminated old buildings sustain exposure to fungal particles and mycotoxins, while urine tests only show exposure?

Repeated work in damp, water-damaged, or mold-contaminated older buildings can create ongoing occupational exposure opportunities, especially during activities that disturb contaminated materials.

Exposure and health relevance

• Damp and mold-contaminated materials release airborne spores, fungal fragments, allergens, and other microbial products. Repeated exposure is most plausible during demolition, cleaning, maintenance, or remediation; concentrations depend on moisture, ventilation, contamination extent, and disturbance intensity.
• Airborne mycotoxins have been directly measured in contaminated workplaces: one validated LC–MS/MS study quantified seven mycotoxins across three workplaces, and another found mycotoxins in 9 of 41 air samples as well as in settled dust and HVAC filters.
• Damp or mouldy buildings are associated with increased respiratory symptoms, respiratory infections, and asthma exacerbations. This association does not establish that a particular measured fungal species or mycotoxin is the responsible agent.

Urinary mycotoxin interpretation

• For selected validated biomarkers, urine can support recent internal exposure. Urinary aflatoxin metabolites (AFM₁ and AF-N7-Gua) generally reflect intake over roughly 24–72 hours; urinary ochratoxin A correlates moderately with estimated dietary intake.
• A positive result cannot distinguish food-related from occupational, environmental, or indoor exposure. Low concentrations may occur in healthy people and commonly reflect dietary exposure.
• Urinary findings therefore cannot establish that a specific building caused exposure or symptoms. This is particularly important for roridin E and chaetoglobosin A, which lack validation as urinary markers of damp-building exposure.

Practical implications

• Building assessment should prioritize identifying and correcting moisture damage, musty odors, and visibly damaged materials rather than relying on routine mold air testing or urine panels for source attribution. Moisture repair, removal or drying of damaged material, containment, and task-appropriate worker protection are the actionable controls.

Bottom line

• Repeated work in mold-contaminated buildings can sustain airborne fungal-particle exposure and can include mycotoxin exposure; urinary mycotoxin testing may indicate recent exposure for certain analytes, but cannot identify its source or prove building responsibility.