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Mold infestation
of wet spray applied cellulose insulation (WSACI) in a crawlspace-Case
History #1
Several years ago a residence was both
inspected and air tested for mold because of reported health problems
experienced by the homeowner. In this case WSACI was applied to the
walls of a crawlspace that opened into a larger basement. An
air-conditioning air handling unit was located in the crawlspace close
to the WSACI on concrete walls. Airborne mold testing in living spaces
revealed the presence of elevated mold levels (> 5000 Spores/M3)
that were dominated by the genus Aspergillus. Stachybotrys
chartarum spores were also observed in collected samples. Bulk
samples of the WSACI were collected prior to abatement. On placing
fragments of the WSACI on culture plates, both the presence of
Stachybotrys chartarum and
Aspergillus versicolor was confirmed. Subsequent to these
analyses samples were submitted to a commercial laboratory tfor analysis
using quantitative PCR, a mold DNA recognition/quantification
procedure. Mold genera identified in a sample subject to rewetting as a
result of a leak in the concrete wall included Aspergillus versicolor,
Penicillium chrysogenum, and Stachybotrys chartarum at these
respective concentrations 9 cells/milligram(mg), 12 cells/mg, and 96,000
cells/mg. In a second sample (not subject to direct rewettingl the same
species were observed with these respective concentrations: 140
cells/mg, 200 cells/mg, and 27,000 cells/mg. As can be seen 3 mold types
characteristic of very moist materials were present with very high
concentrations of Stachybotrys chartarum, the black toxic mold.
Less well known is that Aspergillus versicolor is also a toxic
mold species.
The WSACI in this case was subject to
rewetting as a result of water seepage through the concrete crawlspace
wall. The first sample was in direct line of this seepage. The second
sample was from an overspray on adjacent flooring materials. As one can
see in both cases, samples were subject to significant infestation by
Stachybotrys chartarum.
It can be said that this is an unusual
WSACI application as (at present) it is intended to be applied in
sidewalls that are subsequently enclosed or increasingly in attics.
Because this is not a “normal” place to use WSACI does it diminish in
any way its significance as a product that has the potential to result
in significant residential mold infestation and human exposure problems?
The answer of course is no. In this case it resulted in elevated
concentrations of Aspergillus versicolor and Stachybotrys chartarum
in occupied building spaces and a potential exposure hazard.
Let’s look at what this case history
means. Firstly, it confirms that heavy mold infestation can occur on a
product that should not in theory grow much mold because of the presence
of mold-inhibiting borates (boric acid). Secondly it shows that at
least in this case WSACI was an excellent growth medium for
Stachybotrys chartarum, the toxigenic black mold. Thirdly the
presence of Stachybotrys chartarum in bulk WSACI samples was
consistent with the presence of Stachybotrys chartarum in
the air of occupied building spaces.
In theory the boric acid should have
provided continued protection from mold infestation even after
rewetting. It of course did not. In the second case growth of
Stachybotrys chartarum, Aspergillus versicolor, and Penicillium
chrysogenum occurred apparently in the absence of direct rewetting.
Readers in the states of Indiana, Ohio, Michigan, Illinois and
Kentucky who may be experiencing WSACI-
related mold problems are welcome to contact the author of this
posting at
00tjgodish@bsu.edu as he is interested in conducting additional
investigations to determine the nature and extent of mold
infestation/exposure problems associated with wet spray applied
cellulose insulation.
September 11, 2003
Indoor
Environmental Quality (2000), Thad Godish Ph.D., C.I.H
Direct E-mail
00tjgodish@bsu.edu
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