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An Investigation into Techniques for Cleaning Mold-Contaminated Home Contents



This study examined the efficacy of the following treatments to reduce selected fungal spore and mycotoxin levels on materials commonly found in home contents: (1) gamma irradiation at a 10-13 kiloGray exposure, (2) a detergent/bleach wash, and (3) a steam cleaning technique. A minimum of six replicates were performed per treatment. Paper, cloth, wood, and carpet were inoculated with either fungal spores (Stachybotrys chartarum, Aspergillus niger, Penicillium chrysogenum, or Chaetomium globosum) at 240,000 spores/2.54 cm2 of material or with the mycotoxins roridin A, T-2, and verrucarin A at 10 microg per 2.54 cm2 of material. Treatments were evaluated with an agar plating technique for fungal spores and a yeast toxicity culture assay for mycotoxins. Results showed that gamma irradiation inactivated fungal spores, but the treatment was not successful in inactivating mycotoxins. The washing technique completely inactivated or removed spores on all materials except for C. globosum, which was reduced on all items except paper (p < 0.05). Washing inactivated all mycotoxins on paper and cloth but not on carpet or untreated wood (p < 0.001). The steam cleaning treatment did not completely eliminate any fungal spores; however, it reduced P. chrysogenum numbers on all materials, C. globosum was reduced on wood and carpet, and S. chartarum was reduced on wood (p < 0.05). Steam cleaning was unsuccessful in inactivating any of the tested mycotoxins. These results show that the bleach/detergent washing technique was more effective overall in reducing spore and mycotoxin levels than gamma irradiation or steam cleaning. However, the other examined techniques were successful in varying degrees.
Journal of Occupational and Environmental Hygiene, 1: 442–447
ISSN: 1545-9624 print / 1545-9632 online
2004 JOEH, LLC
DOI: 10.1080/15459620490462823
An Investigation into Techniques for Cleaning
Mold-Contaminated Home Contents
S.C. Wilson, T.L. Brasel, C.G. Carriker, G.D. Fortenberry, M.R. Fogle,
J.M. Martin, C. Wu, L.A. Andriychuk, E. Karunasena, and D.C. Straus
Center for Indoor Air Research, Department of Microbiology and Immunology, Texas Tech University
Health Sciences Center, Lubbock, Texas
This study examined the efficacy of the following treatments
to reduce selected fungal spore and mycotoxin levels on materi-
als commonly found in home contents: (1) gamma irradiation
at a 10–13 kiloGray exposure, (2) a detergent/bleach wash,
and (3) a steam cleaning technique. A minimum of six repli-
cates were performed per treatment. Paper, cloth, wood, and
carpet were inoculated with either fungal spores (Stachybotrys
chartarum, Aspergillus niger, Penicillium chrysogenum,or
Chaetomium globosum) at 240,000 spores/2.54 cm
of mate-
rial or with the mycotoxins roridin A, T-2, and verrucarin A at
10 µg per 2.54 cm
of material. Treatments were evaluated with
an agar plating technique for fungal spores and a yeast toxicity
culture assay for mycotoxins. Results showed that gamma ir-
radiation inactivated fungal spores, but the treatment was not
successful in inactivating mycotoxins. The washing technique
completely inactivated or removed spores on all materials
except for C. globosum, which was reduced on all items except
paper (p < 0.05). Washing inactivated all mycotoxins on paper
and cloth but not on carpet or untreated wood (p < 0.001). The
steam cleaning treatment did not completely eliminate any fun-
gal spores; however, it reduced P. chrysogenum numbers on all
materials, C. globosum was reduced on wood and carpet, and
S. chartarum was reduced on wood (p < 0.05). Steam cleaning
was unsuccessful in inactivating any of the tested mycotoxins.
These results show that the bleach/detergent washing technique
was more effective overall in reducing spore and mycotoxin
levels than gamma irradiation or steam cleaning. However, the
other examined techniques were successful in varying degrees.
Keywords contents, fungi, mycotoxin, sick building syndrome,
Address correspondence to: S.C. Wilson, Department of Micro-
biology and Immunology, TTUHSC 3601 4th Street, Lubbock, TX
79430; e-mail:
here is a great deal of confusion and misinformation
both on the Internet and in other media regarding the
status of household contents in mold-contaminated
structures. This is because there are no studies that
show a relationship between items from a mold-contaminated
structure and human health. Additionally, there are no accurate
and comprehensive testing methodologies for determining
what levels of spores and/or mycotoxins are present on contents
inside structures. For example, the identification of fungal
colonies on contents can be performed using tape lift and swab
however, some items may have spores hidden
inside them or in hard to reach areas, and these sampling
techniques are often inadequate to extract the spores. Sam-
pling techniques for spores and hyphae on contents are there-
fore best viewed as being approximate and not comprehensive
Despite the limitations in determining the extent of fungal
contamination on contents, and the lack of knowledge regard-
ing the relationship between levels of fungal spores and/or
mycotoxins and human ill-health, there is a requirement for a
solution regarding the appropriate treatment of contents in a
mold-contaminated dwelling. The purpose of this study was
to investigate some sterilizing procedures that may be effec-
tive in eliminating fungal spores and mycotoxins on home
epresentative materials of household contents used in the
study were wood, cloth, paper, and carpet. Fungal spores
or mycotoxins were inoculated separately onto the materials.
Three techniques were used for cleaning/sterilizing the ma-
terials: (1) gamma irradiation, (2) a washing technique using
a commercially available detergent/bleach combination, and
(3) a commercial steam cleaner.
The paper was general purpose printing paper (Hp multipur-
pose paper; Hewlett Packard Co., Palo Alto, Calif.). The cloth
was a white 65% cotton/35% polyester material (No. 556092;
Landau Uniforms, Memphis, Tenn.). The wood was untreated
5-ply plywood, 63 mm thick. The carpet was a white 100%
nylon pile with a woven polypropylene backing (Williamsville
06600 Color 127 fleece; Lowe’s Home Improvement Center,
442 Journal of Occupational and Environmental Hygiene July 2004
Lubbock, Texas). The materials for sampling were cut into
1-inch squares (2.54 cm
) and sterilized by autoclaving before
Fungal Spore Inoculation onto Materials
The fungi Aspergillus niger, Stachybotrys chartarum, Peni-
cillium chrysogenum, and Chaetomium globosum were recov-
ered from contaminated building materials and subcultured
onto malt extract agar (MEA) plates.
These plates were in-
cubated at 25
C until conuent growth was achieved, typically
between 67 days. Spores were collected from these plates and
inoculated into phosphate buffered saline (PBS), pH 7.0 at a
rate of 240,000 spores/50 µL of PBS. The 50 µL PBS spore
suspension was inoculated onto the materials and allowed to
dry at room temperature before the experimental treatments
of washing and steam cleaning were applied. This level of
spores, if untreated, would result in conuent fungal growth
on the material after 7 days of incubation.
Mycotoxin Inoculation onto Materials
Because trichothecene mycotoxins are produced by
sick building syndrome-associated organisms such as
S. chartarum,
in this trial, two macrocyclic trichothecenes
(roridin A and verrucarin A) and one simple trichothecene
(T-2) were used. The mycotoxins were inoculated at a level
of 10 µg per square inch of material. This was achieved by
suspending 200 µg of the mycotoxins into a 1.0 mL solution
of 99.9% high-performance liquid chromatography (HPLC)
grade methanol giving a nal concentration of 10 µg/50 µL.
The 50 µL was inoculated onto the materials and allowed to
dry at room temperature before the experimental treatments
were applied.
Experimental Treatments: Washing
The spore- and mycotoxin-inoculated materials were placed
separately into sterile plastic tubes containing 15 mL of a 2%
solution of a commercial detergent (Xtra; USA Detergents Inc.,
North Brunswick, N.J.) and a 2% solution of chlorine bleach
(Ultra Clorox Regular; The Clorox Co., Oakland, Calif.) in
deionized water. The temperature of the solution was 39
The tubes were agitated vigorously, three times per min for a
total of 10 min. The tubes were then emptied of the solution
and rinsed three times with deionized water for 5 min each in
the same manner washing was performed. Positive and nega-
tive controls were included, that is, materials were inoculated
but did not receive the experimental treatment, and materials
received the experimental treatment but were not inoculated.
This procedure was replicated six times.
Experimental Treatments: Steam Cleaning
A commercial dry steam vapor cleaner with a 3 L ca-
pacity was used (Eurosteam, Crowley, Texas). The cleaner
was operated at a high-heat, low-moisture setting. The steam
was directed onto the spore and mycotoxin inoculated materials
from a distance of 6 inches for 10 sec. This procedure was
replicated six times.
Experimental Treatments: Gamma Irradiation
Because the fungicidal activity of gamma irradiation is well
in this trial the main focus was its effects on
mycotoxins; however, its effect on the spores of the selected
organisms was also determined. Sterile cotton swabs were used
to retrieve 2.54 cm
of growth of the four different fungi from
conuent growth on MEA plates. In terms of mycotoxins, the
inoculation technique was the same as used for the washing
and steam cleaning techniques.
After the materials and swabs had been inoculated, they
were transported to a commercial nuclear facility and irra-
diated at a dosage between 1013 kiloGrays. Ten kiloGrays
are equivalent to one megaRad. Positive and negative controls
were employed, that is, materials and swabs were inoculated
but did not receive an experimental treatment, and materials
and swabs received the experimental treatment but were not
inoculated. This process was replicated six times.
Determination of Treatment Efficacy: Fungal Spores
After the washing and steam cleaning treatments, the mate-
rials were retrieved from the tubes, dried, and placed in 10 mL
of PBS. After 5 hours the samples were serially diluted using
PBSata1in10dilution rate three times. One hundred µLof
each dilution was then added to potato dextrose agar (PDA)
plates. After the gamma irradiation treatment, the inoculated
swabs were directly plated onto PDA media.
All agar plates
were incubated for 7 days at 25
C. After 7 days, colony forming
units (CFU) of fungi were identied using macroscopic and
microscopic morphology
and counted.
Determination of Treatment Efficacy: Mycotoxins,
Toxin Extraction
After the washing, steam cleaning, and gamma irradiation
treatments, all materials were suspended in 15 mL of 99.9%
HPLC grade methanol and allowed to soak for 18 hours. The
methanol was then poured into 20-mL glass scintillation vials.
The crude toxin extract was allowed to dry to completion under
a fume hood. The dried remnants were resuspended in 1 mL
of 99.9% HPLC methanol and ltered through polyvinylidene
uoride membrane lters with a pore size of 0.22 microns.
The resulting ltrates were then used for toxicity testing using
a yeast toxicity assay.
Yeast Toxicity Assay
This assay is based on the procedure of Engler et al.
principle of this assay is as follows: cultures of Kluyveromyces
marxianus (No. 8554; American Type Culture Collection,
Manassas, Va.) are incubated with the ltrates for 8 hours.
The yeast culture is sensitive to the presence of trichothecene
mycotoxins and will not grow in their presence even at very
small quantities (100250 nanograms/mL). Optical density
(OD) readings are made every 2 hours. The assay is terminated
at 8 hours. A high OD is a result of increased turbidity, which
is a consequence of the growth of the organism. A low OD is
due to little or no growth of the organism.
Journal of Occupational and Environmental Hygiene July 2004 443
K. marxianus was grown at 37
C and stored at 4
C on yeast-
peptone-glucose (YPG) agar. Cultures for inoculation of the
assay were prepared by adding a single colony from an agar
plate to 5 mL YPG-50 media in a culture tube. The tube was
incubated in a rotary incubator for approximately 16 hours at
C to give the culture a nal density of 1 × 10
cells/mL of
For the assay procedure, YPG-50 was supplemented with a
stock solution of polymixin B sulfate (PMBS) (ICN Biomed-
icals, Aurora, Ohio) to give a nal bioassay PMBS concentra-
tion of 15 mg/mL. Tests were run in triplicate. One hundred
and thirty-six µL of PMBS-supplemented YPG-50 medium
was added to the wells of a 96-well polystyrene microtiter
plate. Eight µL of test sample or control was added to each
well, followed by 16 µL of yeast inoculum to yield an initial
cell density of approximately 1 × 10
cells/mL. Blank wells
contained 152 µL of medium and 8 µL of water. Control wells
consisted of 144 µL of medium and 16 µL of yeast inoculum.
The plates were sealed and incubated on a plate shaker at 37
for 8 hours (when cells reached stationary phase). Cell density
was measured every 2 hours by measuring the absorbance
in a microtiter plate reader at a wavelength of 550 nm. The
absorbance was correlated with a K. marxianus 8-hour growth
curve to determine cell density.
Statistical Analysis
With regard to fungal spores, mean CFU were determined
from the plates inoculated with the treated materials and were
compared using a Mann Whitney Rank Sum Test (SigmaStat,
software, version 2.0; SPSS Inc., Chicago, Ill.) with the mean
CFU from the plates inoculated with the untreated materials. In
this analysis, because of the difference in efcacy between the
two techniques, the washing and steam cleaning techniques
were compared separately with the controls. With regard to
mycotoxins, mean OD readings from the positive controls
were compared with the mean OD readings from the gamma
irradiated, washing, and steam treated materials using a one-
way analysis of variance test. Conditions of normality and
equal variance were met for this analysis.
Washing Technique: Fungal Spores
Table I shows the results for the washing technique for
fungal spores. All spores except those of C. globosum were
either inactivated or removed from the materials. Mean CFU
of C. globosum were reduced on all items except paper (p <
Washing Technique: Mycotoxins
Table II shows the results with regard to mycotoxin levels.
The mean ODs of the cloth and paper ltrates were higher
than the mean ODs of the ltrates of the positive controls (p <
0.001) and similar to the mean ODs of the negative controls,
indicating that the ltrates were not toxic to K. marxianus
cultures. The mean ODs of the carpet and wood ltrates were
no different from the positive controls (p > 0.05) and lower
than the mean ODs of the negative controls, indicating that the
ltrates were toxic to the K. marxianus cultures.
TABLE I. The Effects of Washing with a Detergent/Bleach Combination on Fungal Spore Activity
Washing Technique N = 9 Control N = 5
Organism Material Mean (CFU/2.54 cm
) SE Mean (CFU/2.54 cm
) SE p Value
C. globosum Wood 72
19.3 636
170 <0.01
Cloth 293
41.1 32446
39077 <0.005
Paper 290
83.6 2720
796.5 >0.05
Carpet 272
112.8 1396
397.6 <0.05
S. chartarum Wood 0 0 1300 748.3 NA
Cloth 0 0 56 33.6 NA
Paper 0 0 1328 2089 NA
Carpet 0 0 1100 1043 NA
P. chrysogenum Wood 0 0 8020 4346 NA
Cloth 0 0 15800 4693 NA
Paper 0 0 32600 5455 NA
Carpet 0 0 5560 1689 NA
A. niger Wood 0 0 8740 6328 NA
Cloth 0 0 1420 542.6 NA
Paper 0 0 8600 6853 NA
Carpet 0 0 12236 991.8 NA
Notes: Controls received spores but no treatment. Different superscripts indicate differences at the level of signicance given in the far column.
SE = standard error.
NA = not applicable.
444 Journal of Occupational and Environmental Hygiene July 2004
TABLE II. Optical Density (Yeast Toxicity Assay for Mycotoxin Activity) Readings After Washing, Steam
Cleaning, or Gamma Irradiation Treatment Techniques
Positive Control Washing Steam Gamma Iradiation
Mycotoxin Material Mean SE Mean SE Mean SE Mean SE
Roridin A Wood 0.4
0.05 0.26
0.009 0.4A 0.05 0.14
Cloth 0.31
0.016 1.24
0.012 0.3A 0.019 0.12
Paper 0.27
0.02 1.28
0.009 0.3A 0.054 0.13
Carpet 0.25
0.028 0.19
0.014 0.3A 0.007 0.23
T-2 Wood 0.46
0.033 0.61
0.03 0.51A 0.009 0.34
Cloth 0.3
0.013 1.3
0.034 0.32A 0.007 0.13
Paper 0.23
0.021 1.29
0.028 0.25A 0.02 0.16
Carpet 0.46
0.034 0.39
0.052 0.56A 0.023 0.29
Verrucarin A Wood 0.34
0.006 0.3
0.037 0.35A 0.011 0.16
Cloth 0.31
0.005 1.31
0.023 0.29A 0.011 0.12
Paper 0.27
0.013 1.3
0.027 0.27A 0.015 0.15
Carpet 0.36
0.008 0.16
0.012 0.32A 0.011 0.27
Notes: N = Six per treatment. Positive controls were materials that had toxins added, but did not receive any treatment. Different superscripts indicate differences
at the p < 0.001 level of signicance.
SE = standard error.
Steam Cleaning Technique: Spores
Table III shows the results for the steam cleaning technique
for fungal spores. Results were mixed, with no organisms being
completely eliminated as with some of the washing results.
Mean CFU of P. chrysogenum were reduced on all materials
(p < 0.05). Mean CFU of S. chartarum were reduced on wood
only (p < 0.01). Mean CFU of C. globosum were reduced on
wood and carpet (p < 0.05). Mean CFU of A. niger were no
different from the positive controls (p > 0.05).
Steam Cleaning Technique: Mycotoxins
Table II shows the results with regard to mycotoxin levels.
The mean ODs of the ltrates from all treated materials were no
different from the positive controls (p > 0.05) and lower than
TABLE III. Effects of a Steam Cleaning Technique on Spore Activity
Steam Cleaning Control
Organism Material Mean (CFU/2.54 cm) SE Mean (CFU/2.54 cm) SE
C. globosum Wood 48
19.4 636
Cloth 10950
21040 32446
Paper 933
590.7 2720
Carpet 343
331.5 1396
S. chartarum Wood 36
59.9 1300
Cloth 50
837 56
Paper 216
162.5 1328
Carpet 363
498.1 1100
P. chrysogenum Wood 321
159.4 8020
Cloth 166
180.1 15800
Paper 1255
575.7 32600
Carpet 1000
816.5 5560
A. niger Wood 1201
782.6 8740
Cloth 166
73.6 1420
Paper 5516
3206.3 8600
Carpet 860
647.5 12236
Notes: Different superscripts indicate a signicant difference at the p < .05 level.
SE = standard error.
Journal of Occupational and Environmental Hygiene July 2004 445
the negative controls, indicating that the ltrates were toxic to
K. marxianus cultures.
Gamma Irradiation: Spores
The MEA plates from the inoculated swabs showed no
growth after 7 days incubation at 25
Gamma Irradiation: Mycotoxins
Table II shows the results with regard to mycotoxin levels.
The mean ODs of the ltrates from all treated materials were
no different from those of the positive controls (p > 0.05) and
lower than the negative controls, indicating that the ltrates
were toxic to K. marxianus cultures.
he results show that all three techniques had varying de-
grees of success on the tested materials, spores, and my-
cotoxins. With regard to the gamma irradiation results, many
studies have been performed on gamma irradiation and myco-
toxins, particularly mycotoxins on grains.
In these stud-
ies, results have been mixed with a range of levels of irradi-
ation being required to inactivate different mycotoxins. Ad-
justing relative humidity during irradiation appears to play a
although some studies have not shown any signicant
Possibly, the increase needs to be large for
the treatment to become effective. In this study the technique
was not successful with dry items, although other studies
have shown gamma irradiation to be effective in inactivating
fungal spores and colonies. If mycotoxin inactivation is not
a concern, then this technique appears to be quite effective,
although attention must be given to the degrading effect of
gamma irradiation on items.
With regard to the washing technique, the failure of the
technique to inactivate C. globosum could be due to a number
of factors, for example, the ascospores of C. globosum are
retained inside a structure known as a perithecium
release, and it is possible that the perithecium played a protec-
tive role in this situation. The bleach used in this trial contained
sodium hypochlorite as the active agent. Sodium hypochlorite
has been shown to have bactericidal properties.
It is also
fungicidal to certain organisms.
One study showed that it
had mixed results at 20
C against Penicillium roqueforti.
In terms of toxins, 20 mL of a 1.3% concentration of sodium
hypochlorite is sufcient to inactivate 20 µg of pure
However, this technique has a proviso that 5%
acetone is used as a rinse afterward to either remove or in-
activate a carcinogenic byproduct, 2,3-dichloro aatoxin B
which is formed out of the inactivation process. Sodium
hypochlorite has also been used to inactivate trichothecene
mycotoxins at a concentration between 3 and 5%.
In this
trial it was successfully used in conjunction with a commercial
detergent on paper and cloth. The failure of this treatment to
inactivate mycotoxins on carpet and wood could be because
the carpet bers presented an effective physical barrier to the
detergent/bleach, and the wood absorbed the alcohol-based
mycotoxin preparations. Both features could prevent the wash-
ing treatment from accessing the mycotoxins.
With regard to the steam cleaning technique, it was not
as effective as the washing technique but was successful in
signicantly reducing C. globosum and S. chartarum spore
burdens on wood. The technique involved a 10-sec spraying
time. It is conceivable that longer time periods could result in
effective removal of spore burdens. Also, using a biocide in
the steam cleaner may provide an effective treatment.
In this study the focus was on the effects of the treatments
on fungal spores and mycotoxins. However, a recent study
showed that fungal colonies can aerosolize large numbers of
antigenic fungal fragments into the environment simultane-
ously with fungal spores. These fragments were shown to
be much smaller than fungal spores. It is possible that these
fragments also carry mycotoxins and contribute to fungal con-
tamination of contents. The cleaning techniques tested in this
trial may be effective against fungal fragments but this remains
to be examined.
While the techniques described have shown varying degrees
of success in inactivating mycotoxins and fungal culturability,
it must be noted that fungal spores can still have allergenic
properties even when they are nonviable. High efciency par-
ticulate air [lter] vacuuming is often used in mold remediation
situations and may have application with regard to the removal
of spores from contents.
n this trial, gamma irradiation at a 1013 Kgy exposure
was successful in inactivating spores of Aspergillus niger,
Stachybotrys chartarum, Penicillium chrysogenum, and
Chaetomium globosum, but not the mycotoxins roridin A, ver-
rucarin A, and T-2 that had been inoculated onto carpet, cloth,
paper, and wood. Washing with bleach and a commercial de-
tergent was effective against spores of A. niger, S. chartarum,
and P. chrysogenum, but not C. globosum. The treatment was
successful against the tested mycotoxins for cloth and paper
materials, but not carpet and wood. The steam cleaning tech-
nique was successful only with spores of S. chartarum and
C. globosum on wood material.
inancial support was provided by Assured Indoor Air
Quality Ltd., Dallas, Texas, and Texas Tech University
Health Sciences Center (TTUHSC). Drs. Stephen Wilson and
David Straus were supported by a Center of Excellence grant
from TTUHSC; Dr. David Straus, Mr. Gary Fortenberry,
Mr. Trevor Brasel, and Ms. Enusha Karunasena were supported
by a grant from the Texas Higher Education Coordinating
Board. The authors would also like to gratefully acknowledge
the technical and material support from Mr. Mark LeGarda of
Steris Isomedix Services, El Paso, Texas.
446 Journal of Occupational and Environmental Hygiene July 2004
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... Data in Table (4) indicated that the soaking process without the tested treatments did not significantly affect mycotoxin inhibition. Our results may appear incompatible and ambiguous with other findings concerning the washing grains process with tap water under pressure which significantly reduces the mycotoxin content in mould-contaminated grains by reducing fungal inocula (Wilson et al., 2004;Fandohan et al., 2005 andJouany 2007). This contradiction may due to differences in the soaking process. ...
... Washing procedures using water or sodium carbonate solution are reported to result in some reduction of mycotoxins in grains (Wilson et al., 2004). This process however may only be used in feeds or commodities which will undergo wet milling or ethanol fermentation otherwise costs of drying would be prohibitive. ...
Mycotoxins are not a new topic and they are certainly not a recent worry. In fact, this year it is a decade since theCouncil for Agricultural Science and Technology(CAST) released its scientific task force report on mycotoxins and their impact on plant, animal and human systems. Back then the economic impact of mycotoxins in the United States alone were estimated to exceed $1.4 billion, through losses in commodity quality and health of livestock. This book is intended to be read by those involved in swine production, whether nutritionists or veteriniarians, by students aiming to increase to increase their understanding of the topic, or merely by curious minds. Knowledge has been gathered from several experts and compiled to produce imformation on a wide range of topics from general concepts on mycotoxins by fungi, to their effects on swine performance, fertility and immunity.
... Once they are no longer in direct contact with recirculating MWF, fungi growing in splash zones are no longer exposed to fungicides incorporated into or added to MWFs. Mechanical removal followed by appropriate cleaning and decontamination procedures are the main way to get rid of molds and related odors (137). ...
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Water-miscible metalworking fluids (MWFs) are used in metal removal and forming operations. For end-use, formulation concentrates are diluted in water - providing conditions conducive to microbial growth and metabolism, and potentially causing fluid biodeterioration and microbiologically influenced corrosion. Microorganisms in the environment are highly diverse and bacteria and fungi had been recovered from these fluids at population densities of > 10⁶ CFU mL⁻¹. Thus, to control microbial bioburdens in MWFs, microbicides are often incorporated into MWF-formulations, used as tankside additives, or both. Some microbicides are suspected as being responsible for adverse health effects. Consequently, their usage has been restricted in recently adopted regulations. Given the limited number of microbicides currently approved for use in MWFs, alternative microbial contamination control strategies are needed. Some of these strategies have already been employed in the market. Studies on microorganisms in metalworking fluids are often hindered by the complexity of the media, especially when trying to examine in-use samples. Historically, microbiological analyses were primarily based on cultivation assays using nutrient-rich media. These analyses have severe disadvantages and the adoption of more reliable test methods is of utmost importance. Here, we review MWF microbiology - discussing possible consequences, and options for both control and condition monitoring testing.
... The longer these building materials stay within the home, the more mycotoxins and fungi can accumulate. 4. The remaining wall materials need to be remediated with a cleaning solution(Wilson et al. 2004). Because trichothecenes were detected on all building materials, including concrete, all remaining materials must be thoroughly cleaned. ...
The major question after a flooding event is whether to remove or remediate the building materials so that potentially harmful mold growth and their by-products cannot cause serious health problems for susceptible individuals. The purpose of this study was to determine the growth of Stachybotrys chartarum and corresponding production of macrocyclic trichothecenes on different components of a residential wall up to 65 days after a simulated flood event. Small-scale residential walls constructed of fiberglass batt insulation, oriented strandboard, gypsum wallboard, and lumber were destructively sampled at four time points. All four building materials contained notable levels of macrocyclic trichothecenes on all collection days. The highest concentrations of macrocyclic trichothecenes were on the paper siding of the gypsum wallboard, followed by the paper siding of the batt insulation and wood lumber. There was a significant increase in trichothecene concentration over time, particularly on the gypsum. The DNA concentrations of the mold were significantly higher on the batt insulation than on the wood products, and the mold concentrations also increased over time on the batt insulation and gypsum, but not on the wood products. It was concluded that if a flooding event should occur, the insulation and gypsum should be removed from the home and the remaining materials should be remediated.
... Behandling med ånga var bara effektivt mot vissa mögelsvampar till skillnad från gammastrålning. Ingen av dessa behandlingar deaktiverade några mykotoxiner (Wilson et al 2004). ...
Technical Report
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När byggnadsmaterial har blivit angripet av mögel används ibland olika saneringsmedel eller metoder för att bli kvitt möglet och ibland torkas bara materialet ut utan åtgärd. Det finns studier som pekar på att sanering med framförallt kemiska medel inte hejdar eller eliminerar mögeltillväxt och på att frigörandet av partiklar från det mögelskadade materialet ökar vid intorkning. IVL Svenska Miljöinstitutet och Lunds universitet har samarbetat i detta projekt där effektiviteten av olika saneringsmedel/-metoder på mögelangripet byggnadsmaterial undersökts. Gipsskivor samt furusplint steriliserades och förorenades sedan artificiellt med kända mögelisolat av arterna Stachybotrys chartarum respektive Aspergillus versicolor. Materialen inkuberades i fuktkammare varefter c:a tio olika metoder/medel applicerades enligt tillverkarnas instruktioner. Mikrobiologiska och kemiska analyser utfördes av materialen före, direkt efter, efter sex veckor i rumstemperatur utanför fuktkammaren och åter efter ytterligare sex veckor i fuktkammaren. Målet med studien var att utröna huruvida de undersökta saneringsmedlena/-metoderna kunde eliminera mögeltillväxt samt destruera de mögelgifter som bildats i mögelskadan. Ingen av de saneringsmetoder som testats kunde eliminera livskraftig mögelväxt på de olika byggnadsmaterialen. I ett fall -med Alg & MögelBORT Proffs- oskadliggjordes den mögelart som materialet ursprungligen infekterats med, men återkolonisering med nya mögelarter förhindrades ej under gynsamma förhållanden. Av samtliga saneringsmetoder var det också bara Alg & MögelBORT Proffs som minskade halten av alla de studerade toxinerna i gipsskiva. I furusplint minskade dock mängden toxiner efter flera behandlingar, i.e. med Penetrox-S, de båda bopreparaten, Klorin, Alg & MögelBORT Proffs samt efter torkning. Inget saneringsmedel eliminerade dock toxinerna helt från det skadade byggnadsmaterialet. Främst understryker projektresultaten vikten av att arbeta preventivt med fuktsäkerhet genom hela byggprocessen och förvaltningen för att förhindra uppkomst av mögelskador på byggnadsmaterial. När mögelskador konstaterats bör verksamhetsutövaren åtgärda orsaken till fuktskadan och även byta ut det skadade materialet.
... Apart from routine household cleaning, there are specific cleaning operations such as professional cleaning of ventilation ducts (Zuraimi, 2010) or cleaning after mold remediation. Thorough cleaning of surfaces, furniture, and ventilation ducts after mold remediation is considered essential to ensure that occupants can safely return (Wilson et al., 2004). Situations requiring even more intensive efforts are the cleanup operations after flooding and hurricanes (Bloom et al., 2009a;Golofit-Szymczak et al., 2012;Rao et al., 2007). ...
This review discusses the role of fungi and fungal products in indoor environments, especially as agents of human exposure. Fungi are present everywhere and knowledge for indoor environments is extensive on their occurrence and ecology, concentrations, and determinants. Problems of dampness and mold have dominated the discussion on indoor fungi. However, the role of fungi in human health is still not well understood. In this review we take a look back to integrate what cultivation-based research has taught us alongside more recent work with cultivation independent techniques. We attempt to summarize what is known today, and to point out where more data is needed for risk assessment associated with indoor fungal exposures. New data have demonstrated qualitative and quantitative richness of fungal material inside and outside buildings. Research on mycotoxins shows that just as microbes are everywhere in our indoor environments, so too are their metabolic products. Assessment of fungal exposures is notoriously challenging due to the numerous factors that contribute to the variation of fungal concentrations in indoor environments. We also may have to acknowledge and incorporate into our understanding the complexity of interactions between multiple biological agents in assessing their effects on human health and well-being.This article is protected by copyright. All rights reserved.
Biological stains are widely used in biomedical research laboratories and also for diagnostic purposes. Dyes of similar structures are used industrially. Some stains can be removed from aqueous solution using the polymeric resin Amberlite XAD‐16. In some cases, the resins Amberlite XAD‐2, XAD‐4, and XAD‐7 can also be used. The decontaminated solution may be disposed of with the nonhazardous aqueous waste and the resin with the hazardous solid waste. Ethidium bromide in H 2 O and buffer solution may be degraded by reaction with sodium nitrite and hypophosphorous acid in an aqueous solution. Many hazardous compounds, such as pesticides and polychlorinated biphenyls, contain halogen atoms. The halogenated compounds are reductively dehalogenated with nickel–aluminum alloy in a dilute base to give the corresponding compound without the halogen. Hypochlorites, in general, and sodium hypochlorite solutions, in particular, tend to deteriorate with time, so they should be periodically checked for the amount of active chlorine they contain.
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Phytopathogenic micromycetes induce dangerous crop diseases. Traditionally, fungicides have been used to prevent these diseases. In recent years, environmentally friendly non-chemical methods for combating fungal infections have been developed. In particular, ultraviolet (UV) treatment of various wavelengths, intensities and origins has been shown to be effective. In this work, we have analysed the effect of diode low-intensity shortwave UV radiation (UV-C) on the growth and potential viability of the mycelium of Alternaria radicina and A. alternata, the pathogens of important crops. It was shown that irradiation by UV-C diode inhibited growth of Alternaria species at the early stages of development. This effect was high in the first 3 d after UV exposure; however, after 5 d after irradiation, the growth of pathogenic fungi fully restored, suggesting that UV can be only used for partial removal of Alternaria. It was found that A. alternata is less sensitive to diode UV irradiation. The obtained results indicate that the Alternaria micromycetes, particularly, A. alternata, containing high melanin levels, are resistant to low-intensity UV-C diode irradiation.
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Esta revisão foi realizada com o objetivo de fazer um breve histórico, caracterizar, descrever as alterações metabólicas, sinais clínicos, métodos de prevenção, controle e detoxificação das principais micotoxinas consumidas por bovinos de corte. Após a descoberta da aflatoxina e dos problemas que esta pode causar para os animais e também em humanos, principalmente câncer, as pesquisas científicas aumentaram ano após ano, e hoje são descritos mais de 18000 metabólitos secundários produzidos por fungos, porém os mais estudados são: aflatoxinas, ocratoxina A, tricotecenos, zearalenona, patulina, fumonisina e alcaloides de Ergot. Os ruminantes de uma forma geral necessitam de maiores concentrações de micotoxinas na dieta quando comparados aos monogástricos para apresentarem sintomas clínicos de intoxicação. Isso acontece pelo fato de que algumas de micotoxinas podem ser parcialmente ou totalmente degradadas pelos microrganismos ruminais. Porém, a fermentação ruminal não resulta necessariamente em inativação da toxina, e a extensão da metabolização depende além do tipo de micotoxina consumida, da espécie animal, idade, sexo, raça, tipo de dieta e consequentemente dos tipos de microrganismos que habitam o rúmen. Além disso, algumas micotoxinas possuem ação antimicrobiana, e podem alterar negativamente o metabolismo ruminal. A presença de micotoxinas na dieta pode afetar além da saúde o desempenho produtivo e reprodutivo o que pode levar a altas perdas econômicas. Assim os sistemas de produção de alimentos para bovinos devem adotar práticas agrícolas que minimizem a produção desses metabólitos.
ABSTRACT Steam vapor has been shown to reduce viable mold spores in carpet, but the minimal effective temperature and contact time has not been established. This study evaluated the effectiveness of steam vapor in reducing the number of viable mold spores in carpet as a function of temperature and contact time. Seventy carpet samples were inoculated with a liquid suspension of Cladosporium sphaerospermum and incubated over a water-saturated foam carpet pad for 24-hours. Steam was applied to the samples as the temperature was measured from the carpet backing. Contact time was closely monitored over seven time intervals: 0, 2, 4, 8, 12, 16, and 20 seconds. Following steam vapor treatment, mold spores were extracted from the carpet samples and the extract was plated on DG-18 plates at 1:1, 1:10, 1:100 dilutions followed by one week of incubation. Raw colony forming units were determined using an automated colony counter and adjusted based on dilution factor, extraction volume, and plated volume. Analysis of variance and linear regression were used to test for statistically significant relationships. Steam contact time exhibited a linear relationship to observed temperature of carpet backing (F=90.176, R(2)=0.609). Observed temperature of carpet backing had a positive relationship to percent reduction of mold (F=76.605, R(2)=0.569). Twelve seconds of steam vapor contact time was needed to achieve over 90%mold reduction on moist carpet.
Hypochlorite has been used as a disinfectant for more than 100 years. It has many of the properties of an ideal disinfectant, including a broad antimicrobial activity, rapid bactericidal action, reasonable persistence in treated potable water, ease of use, solubility in water, relative stability, relative nontoxicity at use concentrations, no poisonous residuals, no color, no staining, and low cost. The active species is undissociated hypochlorous acid (HOCl). Hypochlorites are lethal to most microbes, although viruses and vegetative bacteria are more susceptible than endospore-forming bacteria, fungi, and protozoa. Activity is reduced by the presence of heavy metal ions, a biofilm, organic material, low temperature, low pH, or UV radiation. Clinical uses in health-care facilities include hyperchlorination of potable water to prevent Legionella colonization, chlorination of water distribution systems used in hemodialysis centers, cleaning of environmental surfaces, disinfection of laundry, local use to decontaminate blood spills, disinfection of equipment, decontamination of medical waste prior to disposal, and dental therapy. Despite the increasing availability of other disinfectants, hypochlorites continue to find wide use in hospitals.
Fusarium graminearum andF. tricinctum were grown on moistened corn and rice. After inoculation the substrates were exposed to γ-irradiation and growth rate together with mycotoxin production were measured. A delay in mycelium growth and an increase in F-2 and T-2 toxin production occurred after irradiation with 1 and 3 kGy. The maximum F-2 production was 10.7 mg/kg on rice at 3 kGy, whereas T-2 was 735 μg/kg on rice at 3 kGy. At 9 kGy neither growth nor toxin production could be detected in any inoculated corn and rice substrate.
The paper handles the problem of the inactivation of the toxinogenic strain Aspergillus flavus following the application of gamma radiation to wheat. The amount of the applied dose and of the absorbed dose of ionizing radiation upon the inhibition of mycelium growth and toxin production were defined. The aflatoxin B1 was determined by extracting in chloroform and developed on Silufol R within the choroform; aceton system. The applied doses of gamma radiation (3-30 kGy) have show that the absorbed dose does not inhibit aflatoxin production. By combining the action of gamma radiation with humidity of the wheat (humidity 13-15%; 25% irradiation 6 kGy) an inactivation was reached. With the help of toxicologico-genetical tests (the Dominant Lethal Mutations Test, the Three Generations Test) the influence was traced of contaminated, irradiated substrates upon the health of experimental animals. It follows from the results obtained that in long-term feeding with contaminated wheat irradiated by gamma rays no positive mutagenic activity has been recorded. It allows to presume that wheat of humidity of 25% contaminated by a weakly toxigenic strain Aspergillus flavus irradiated by a dose of 6 kGy, and wheat of a humidity of 13-15%, contaminated by a strongly toxinogenic strain of Aspergillus flavus, irradiated by a dose of 6 kGy, are no genetic risk for white rats.
Ten species of fungi representing the genera Alternaria, Aspergillus, Caldosporium, Curvularia, Fusarium, and Penicillium were examined for their relative resistance to gamma irradiation from a 137Cs source. Inactivation doses for dematiaceous fungi in agar medium ranged from 0.6 to greater than 1.7 megarads, whereas those for moniliaceous fungi were less than 0.3 megarad. D10 values (the dose required to reduce the inoculum by 1 log) for Curvularia geniculata (greater than 0.29 megarad) exceeded those for control spores of Bacillus pumilus (0.15 megarad).
The irradiation sensitivity of fungal spores to either gamma or electron beam irradiation was evaluated in distilled water. The D10 (the dose required to reduce the initial population by 90%) gamma values ranged from 0.236 to 0.416 kGy and from 0.209 to 0.319 kGy for Penicillium and Aspergillus species, respectively. The D10 electron beam values ranged from 0.194 to 0.341 and from 0.198 to 0.243 kGy for Penicillium and Aspergillus species, respectively. Of the aspergilli species evaluated, only half exhibited significantly (P < 0.05) greater sensitivity to the electron beam treatment compared to gamma irradiation. Four of the six penicillia species evaluated also exhibited significantly (P < 0.05) higher sensitivities to electron beam treatment.