EWJ 60 April 2025 web - Journal - Page 83
The Mycotoxin Defence by
Black Pin Mould
A post-doctoral study by Dr Aaran Marriner-Clark FRICS, FISSE, FCABE C.BULD.E,
FNIBME, PNIBME, FRSPH, MRPSA, MBMS, MCIEH, MMSA.
on the walls, it is this that allows for the growth once
low levels of moisture, break down the Calcium and
magnesium and reduce the levels of sodium So4,
which I considered to be a mould limiting factor.
Introduction.
This research study looks to establish that the
mycotoxin increase of 90% found in the research by
Hirvonen et al, 2003 is indeed the black pin moulds
defence mechanism, that can stop eradication of the
mould from homes and allow for it to colonise
dwellings even when biocides are used to eliminate it.
Therefore, we remove the mould limiting factor
sodium So4, by leaching and replace it with high concentrations of calcium Ca, when experiencing water
saturation and ingress in building.
The Research
Calcium Carbonate, Magnesium Silicate, Barium
Sulphate and iron sulphate, are all ingredients of
paint, calcium Ca is the main ingredient of gypsum,
therefore, what we have are buildings that are high in
calcium deposits.
Indeed, a study by STEINBERG, R.A (1946) et.al,
Found that Magnesium, calcium, and strontium increase dry weight production in all the concentrations
imposed on samples. All the fungi tested have their
vegetative growth inhibited by sodium, the fungi
tested had their vegetative growth inhibited by
sodium but the concentration causing inhibition can
differ widely from species to species. Indicating that
the sodium is the limiting factor, however, given the
study by Hirvonen et al., 1997 and 2003 I question if
the increase in mould growth is a response due to the
myotoxicity increase in the Stachybotrys chartarum
seen in the research Hirvonen, which is indeed the
moulds defence mechanism that can stop eradication
of the mould and allow for it to colonise even when
biocides are used eliminate it.
Gypsum is calcium sulphate (CaSO4). Refined
gypsum in the anhydrite form (no water) is 29.4 percent calcium (Ca) and 23.5 percent sulphur (So4).
Usually, gypsum has water associated in the molecular structure though, (CaSO4·2H2O) and is approximately 23.3 percent Ca and 18.5 percent So4.
Gypsum is the neutral salt of a strong acid and strong
base and does not increase or decrease acidity. Dissolving gypsum in water results in the following reaction: CaSO4 Na2SO4·2H2O = Ca2+ + NaSO42- +
2H2O. It adds calcium ions (Ca2+) and sulphate ions
(SO42-), but does not add or take away hydrogen ions
(H+). Therefore, it does not act as a liming or acidifying material. The Ca2+ ions sulphate remains
dissolved in water. As does the SO4 sodium.
Indeed, it was found STEINBERG, R.A 1946 et al,
that even if salt solutions (sodium So4) were imposed
on samples, growth was still obtained when high concentration of calcium Ca is delivered to the samples,
which begs the question is the calcium being delivered
to the samples reducing the mycotoxin response by
the mould in reverse of what Hirvonen et.al, 2003
found in their research. The addition of Calcium Ca
reduces the Myotoxic response, therefore if we increase Calcium Ca before application of biocides
would eradication be effective by biocides.
Given saturation of gypsum occurs in damp homes
due to ingress of water or high condensation, this
would leach the sodium SO4 and allow calcium Ca to
remain within the walls structure. Therefore, this creates ideal conditions for the mould to feed and
colonise the building. Interestingly if we leach sodium
So4 we also leach Calcium Ca but the calcium Ca is
retained at surface and the sodium is leached as
efflorescence.
The Cleaning of a wall with biocides
This would indicate that sodium So4 in the gypsum
plasterwork is a limiting factor for black pin mould
growth and the main reason why black pin mould is
not seen in areas of high efflorescence even when saturated. But colonisation is seen in areas of lower
sodium So4 and higher calcium Ca. once the Calcium
The leaching of sodium from the wall
I hypothesised in my study in 1993 that the black pin
mould is reacting to the availability of magnesium and
calcium in the paint and the gypsum that is evident
EXPERT WITNESS JOURNAL
81
APRIL 2025
