Molds & Mycotoxins
About This Health Driver
Molds are fungal organisms that colonize building materials in the presence of sustained moisture. Mycotoxins are the toxic secondary metabolites produced by certain mold species (Stachybotrys, Aspergillus, Penicillium, Fusarium, and others). In indoor environments, mycotoxin exposure occurs through inhalation of spores and fragments, dermal contact, and ingestion. The indoor biological cascade extends beyond mold itself to include microbial volatile organic compounds (mVOCs), bacterial endotoxins, and the broader biological ecosystem that moisture supports.
How It Affects Bodies
Mycotoxins produce neurotoxic, immunotoxic, and genotoxic effects. Trichothecenes inhibit protein synthesis. Ochratoxin A is nephrotoxic and potentially neurotoxic. Aflatoxins are carcinogenic and immunosuppressive. At sub-clinical chronic exposure levels typical of water-damaged buildings, the dominant effects are immune dysregulation and chronic inflammatory activation. Mold fragments and spores activate innate immune responses through pattern recognition receptors, producing a sustained inflammatory state. mVOCs contribute to the volatile chemical load in indoor air.
Where It Comes From
- Water intrusion through the envelope - roof leaks, flashing failures, window and door penetrations
- Condensation in wall assemblies - vapor drive mismatch, thermal bridging, inadequate vapor management
- Plumbing leaks - supply lines, drain lines, fixture connections, water heater failures
- HVAC condensate - clogged drain lines, standing water in drain pans, coil contamination
- Elevated indoor humidity - inadequate dehumidification, poor ventilation, occupant moisture generation
- Flood or storm damage - standing water, saturated materials not dried within 48 hours
- Foundation moisture - slab wicking, crawl space humidity, inadequate vapor barriers
How to Address It
- Vapor-open wall assemblies - climate-appropriate vapor management strategyEnvelope
- Dedicated dehumidification - sized to full latent load, independent of coolingMechanical
- Indoor humidity monitoring - target 30-45% RH; smart hygrometers with alertsOperations
- Mold-resistant substrates in wet areas - cement board, fiberglass-faced drywall, solid surfaceInteriors
- Drainage planes and rain screens - secondary moisture management behind claddingEnvelope
- Water leak detection - electronic sensors at all fixtures, water heater, HVAC condensatePlumbing
- Exhaust ventilation in wet rooms - minimum 50 CFM bathroom fans vented to exterior; range hood vented to exteriorMechanical
- Crawl space encapsulation - vapor barrier, dehumidification, sealed ventsEnvelope
- HVAC maintenance protocol - coil cleaning, condensate drain inspection, filter changesOperations
- 48-hour response protocol - documented in operating manual for any water intrusion eventOperations