Expert Witness Journal Issue 64 December 2025 - Flipbook - Page 97
The increase in mycotoxin toxicity is a very
important paradox in mould remediation as
fungicidal treatments can unintentionally worsen
the toxicological pro昀椀le of the contamination.
Key causation chain:
Structured causation chain:
•
•
Surface Treatments and pH Adjustment Biocides and
sealants are often applied to gypsum, plasterboard,
or paper facings to suppress fungal growth. pH
adjustment (acidi昀椀cation toward ~3-4) reduces
substrate suitability for Stachybotrys chartarum
growth.
•
Safer Alternatives
In theory, combining these measures should create
a hostile environment for mould colonisation.
•
•
Forensic considerations
•
•
In housing disputes, demonstrating that gypsum
has been left alkaline (e.g., pH >9) can explain
persistent Stachybotrys growth.
Acidi昀椀cation protocols can be cited as remedial
measures that directly alter the substrate
ecology, reducing fungal viability without
relying solely on biocides.
•
•
•
•
•
Hygroscopic salts: Residual NaCl and NaClO attract
moisture, elevating local equilibrium moisture
content and slowing drying. This leaches the sodium
after bleaching has occurred over time due to
structural defects.
Research indicates that fogging and fungicidal
application can increase mycotoxin toxicity
by ~90.9%. the mechanism of biocides does not
work in that event.
Fungicides stress fungal cells, triggering
secondary
metabolite
overproduction
(including trichothecenes).
Dead or stressed spores may release higher
concentrations of bound mycotoxins into the
environment.
This means eradication attempts can increase
airborne toxicity, even if visible mould growth
is reduced.
Wetting And Drying Cycles
Rewetting risk: Salt-laden surfaces can more readily
reabsorb ambient moisture, this leaches the sodium
and makes the calcium available to the Stachybotrys
chartarum given time for the leaching to occur.
When moisture is reabsorbed:
•
Given this the application of biocides does not
control or eradicate the colonisation of Stachybotrys
Chartarum.
•
•
Implications for Stachybotrys Chartarum
•
Stachybotrys
Chartarum
produces
potent
trichothecene mycotoxins (e.g., satratoxins). Under
stress (biocide exposure, fogging), the fungus will:
•
•
•
Intensi昀椀es toxin synthesis as a defensive
response.
Releases toxins into dust and debris, which
remain hazardous even after fungal death.
Thus, eradication by fungicides can negate
the remediation process, leaving a more toxic
environment than what we started with.
EXPERT WITNESS JOURNAL
Physical removal of contaminated materials
(cut-out and replace gypsum/paper facings).
Environmental control: humidity reduction,
ventilation, and substrate a low pH stabilization.
Non-fogging approaches: localized cleaning
with neutral pH surfactants, followed by sealing
with breathable, non-toxic coatings.
Monitoring: post-remediation air and dust
sampling to con昀椀rm toxin reduction, not just
fungal absence.
Moisture dynamics:
Fogging and Fungicidal Agents
– The Toxicity Paradox
•
Chemical treatment fungal stress increased
mycotoxin release higher toxicity remediation
failure.
In housing disputes or expert witness contexts,
this demonstrates why biocide-only strategies
are insu昀케cient and can worsen occupant
exposure.
Evidence of increased toxicity post-treatment
can be used to argue for alternative remediation
protocols.
Sodium salts dissolve and migrate with capillary
action.
This mobilizes ions within the pore network.
Over time, calcium sulphate (CaSO4·2H2O)
can partially dissolve, releasing Ca²+ into the
pore water. Which the Stachybotrys Chartarum
responds to.
The leaching is relatively slow but cumulative,
especially under repeated wetting–drying
cycles. However, this process is sped up when
leaching occurs through structural defects.
Implications for Stachybotrys Chartarum
•
•
94
Stachybotrys
thrives
in
cellulose-rich,
persistently damp substrates (e.g., gypsum
board paper facings).
It requires calcium and other cations for
enzymatic activity and sporulation.
DECEMBER/JANUARY 2025-2026
