This article was originally prepared for and published in the
June, 1995 edition of Alberta Bee News, which is published by
the Alberta Beekeepers Association (ABA). See the end of the
article for further information and addresses.
We feel that the subject matter is serious enough that it should
receive wide publication. This is our first attempt to post
something like this and we apologize if the formating is not good.
DANGER IN THE HONEYHOUSE
by Kenn Tuckey
Is your health in danger from your work as a beekeeper? A new
study suggests that at certain times of the year beekeepers are at
great risk of disease from airborne mold spores.
This article is based on the final report on "ASSESSMENT OF
AIRBORNE MOLDS AS A BIOLOGICAL HAZARD FOR ALBERTA COMMERCIAL
BEEKEEPERS" by Henry Gauvreau, Lynne Sigler and Sean Abbott, dated
March 1995. Dr. Gauvreau was at Fairview College, Alberta, Canada
and is currently at the Fairview Diagnostic Veterinary Laboratory,
Alberta Agriculture, Food and Rural Development. Sigler and Abbott
are at the University of Alberta Microfungus Collection and
Herbarium, Devonian Botanic Garden, Devon, Alberta Canada. The
study was funded by Alberta Occupational Health and Safety,
Heritage Grant Program and in part by the Canadian Honey Council
(CHC) (using FSAM II funds).
The study was prompted by observations of mold growth in the
Fairview College honey bee overwintering facility. Dr. Gauvreau
did a preliminary study of mold spores in the facility when the
dead bees were being swept from the floor and when the bee
equipment was being cleaned. In both cases the results showed that
the levels, and types, of airborne mold spores were sufficient to
cause concern for worker safety. This led to the larger study
named above.
Depending on the species involved, mold spores have the potential
to create many problems for beekeepers (or any humans). Many
people are allergic to mold spores and frequently have adverse
reactions at specific times of the year eg. snow mold in the
spring. Some molds are known to have toxic effects on people and
under the right conditions other molds can lead to disease. The
report states "The presence of known toxigenic, potentially
pathogenic and allergenic molds at all sites suggests that prudent
action is needed to minimize worker exposure".
A health survey questionnaire was returned by 64 beekeepers. The
survey asked about respiratory and flu-like symptoms as well as
eye, ear, nose and throat problems. The beekeepers reported that
there seemed to be a relationship between the work being done and
the symptoms being experienced. The report indicates that more
studies are needed in this area but concludes that "there appears
to be a strong association between reported respiratory symptoms,
eye, nose and throat irritation and the activities monitored
(sweeping and cleaning) where there was exposure to high levels of
airborne molds".
Testing Methods
The co-operating beekeepers were selected to give results from all
across the province as well as for size of operation. For the
wintering section air quality samples were taken in the fall
(shortly after the bees were moved in), in mid-winter
(January/February), and again just before the bees were moved out.
A air sampler was used during each of the tests. The machine draws
air into it at a constant, known rate for 4 minutes and a fan
knocks the spores down onto a agar strip that contains nutrients
that induce the spores to germinate and grow into mold colonies.
After incubating for 5 days the strips are examined to count the
number of mold colonies. The mold colonies were then recultured on
new agar so that they could be identified.
Background samples were taken outside and upwind of the building
(or, rarely, in an adjacent room). In the wintering buildings air
samples were taken in the wintering room before the bees were
cleaned from the floor and during the cleaning process. In the
other part of the study samples were taken in the work room while
the bee equipment was being cleaned. The air samples in the
buildings were taken 5'5" from the floor to approximate the
breathing level of workers.
The large numbers of mold spores found in the air required some
deviation from normal procedures. The testing time was reduced
from the four minute standard to tests of 30 seconds and one minute
in order to reduce the number of spore colonies to countable
levels. In addition, the incubation time was reduced from 5 to 3
days to prevent the spore colonies from growing into each other and
being difficult or impossible to count or identify. After the
examination at 3 days the strips were reincubated for an additional
two days and recounted if possible.
The incubation, counting and identification of the molds was
primarily done at the Herbarium.
Results
The results for counts of mold spores in air is given as CFU/m3.
This means the number of Colony Forming Units per cubic meter of
air. Theoretically, each spore that is captured will produce a
colony that can be counted.
The report indicates that there are no hard and fast standards for
minimum levels of mould spores in the air in work places but that
the most commonly accepted standards "suggest that levels of
airborne molds greater than 150 CFU/m3 for a mixture of species are
unacceptable in indoor air. Counts as high as 500 CFU/m3 are
acceptable only if the species recovered are primarily phylloplane
(plant litter) fungi and reflect outdoor mycobia." (Note: molds
are fungi but not all fungi are molds eg. mushrooms.)
As the table from the report shows, in all cases the number of
CFU/m3 found during the floor cleaning process exceed this minimum
level. In most cases the contamination is many times the
acceptable level.
Colony forming units (CFU) of airborne molds at overwintering
facilities.
Airborne mold levels (CFU/m3)
Site Sample
Period Presweep Sweep Outside
30 sec 1 min 30 sec 1 min 4 min
-----------------------------------------------------------------
FC fall 100 425 13500 NE 56
winter 600 1550 26100 10175 63
spring 350 725 8450 10100 16
JS fall 3300 1175 11850 6025 128
winter 350 325 1650 4675 38
spring 300 175 9600 3700 44
PB fall 300 350 19700 NE 934
winter 300 750 3900 7200 38
spring 550 750 8850 4625 25
RP fall 600 350 600 1250 34
winter 800 650 9900 11925 150
spring 550 1075 14350 5350 406
RR fall 650 425 1400 1975 94
winter 400 675 1350 4400 613
spring 400 475 1550 11575 131
SW fall 400 100 850 325 88
winter 200 275 4800 2100 106
spring 250 200 5450 7100 38
DB fall 500 225 1050 525 75
winter 950 1100 2400 4425 650
spring 1050 725 3500 1300 238
DP fall 500 450 4200 1475 231
winter 300 375 400 1000 188
spring 1900 4025 9250 7300 2613
EW1 fall 600 425 4150 2250 363
winter 300 500 6750 4350 69
spring 1150 1550 3700 7100 94
EW2 fall 1550 1250 11400 NE 225
winter 650 450 19850 4175 100
spring 2350 2400 20300 NE 69
NE =3D not enumerable due to extremely high colony density or
overgrowth by rapidly growing molds.
The results from the equipment cleaning part of the study, as shown
in the table, show similar numbers.
Colony forming units (CFU) of airborne molds at equipment cleaning
facilities
Airborne mold levels (CFU/m3)
Site Sample During cleaning Outside
Period 30 sec 1 min 4 min
------------------------------------------------
TEG fall 7050 5725 76 (inside adjacent room)
DBW spring 24400 8750 3425
RRW spring 47700 NE 463
HT spring 23750 20825 319
HW spring 52450 NE 719
LW spring 43450 NE 2469
PBW spring 8000 4850 394
JG spring 17900 17575 125
DM spring 54700 NE 369
MW spring 2250 5350 375
BL spring 750 875 144
BLY spring 2400 11925 69
GH spring 22300 10025 81
JC spring 300 350 125
SM spring 13850 10650 3806
NE =3D not enumerable due to extremely high colony density or
overgrowth by rapidly growing molds.
>From the table, it is very obvious that the act of cleaning the
dead bees from the floor creates a cloud of mold spores and exposes
the worker to a much increased level of spores. The report notes
that one beekeeper used a squeegee rather than a broom and that the
increase in spore count was reduced in that facility.
Appendix A of the report lists each of the molds identified in each
facility. The report also lists the 82 species of mold that were
collected during the study. Forty-eight of those molds are
reported to be potentially pathogenic, potentially toxigenic,
allergenic or two or three of those factors. The report gives
details of the negative effects many of these molds have on human
health and indicates their frequency of occurrence in each
facility. The report indicates that while the molds may not be
especially dangerous to healthy individuals the effect of long
term, frequent exposure to such high levels of spores in unknown.
Recommendations
The report provides five recommendations:
1. Airborne mold levels are extremely high in all beekeeping
overwintering and equipment cleaning facilities sampled in
Alberta, regardless of physical attributes of buildings and
maintenance practices. Therefore, these buildings should be
considered as highly contaminated sites and appropriate
precautions should be taken while working.
2. Workers need to follow safety precautions while sweeping and
cleaning in order to reduce or eliminate exposure to airborne
mold spores, organic particulates, mycotoxins and volatiles.
This should include wearing a respirator capable of filtering
small organic particles (<2 =B5m diameter) and volatile chemical
compounds. Wearing eye protection, overalls and gloves which
can be removed and washed is also recommended.
3. Advise beekeepers of potential risks of exposure to molds
through development of an information brochure.
4. Maintenance practices which reduce aerosolization of mold
spores, and therefore reduce worker exposure, should be
encouraged. This may include using a rubber squeegee rather
than a broom to sweep dead bees from the floor.
5. In cooperation with the industry, investigate alternative
management practices in overwintering facilities to reduce
airborne mold levels.
Notes on the recommendations:
#2 These respirators are available from safety supply houses.
Dr. Gauvreau indicates that for an increased margin of safety
filters effective down to 1 =B5m (1 micron) should be used.
I have found that at least two companies (Scott and Wilson)
make suitable respirators at a cost of $30 to $35. Each
respirator requires a pair of cartridges at an additional
cost of $25 to $30 per pair. HEPA (high efficiency particulate)
Organic Vapour Cartridges are required. To find these products
contact safety supply companies close to you.
At least one of the equipment cleaning sites (BLY) was located
outdoors. The table shows that the mold level was greater
there than at some of the indoor cleaning sites. This indicates
to me that we cannot rely on good ventilation to protect us
from high levels of spores. However, since the mold spores
are very small and light, a good ventilation system that moves
a lot of outside air through the work room has to be helpful.
A ceiling fan that just circulates air could very well be harmful.
#4 Moistening the bees on the floor may be an alternative but
the ramifications would have to be carefully thought through.
What would be the effect of the extra humidity in the air and
on the floor for further mold growth? The cleaned up bees
could rot in the containers if moisture is added.
#5 If you have suggestions on how to reduce the health risk
please pass them on so that all beekeepers may weigh their
use for their own management.
Conclusion
The full report is 72 pages long and has a great deal more detailed
information than I have been able to include in this article.
Contact me if you would like to borrow the report for more in
depth study.
Further Information:
Study Senior Author: Dr. Henry Gauvreau
Fairview Diagnostic Veterinary Laboratory
Alberta Agriculture, Food and Rural Development=
Fairview, Alberta, Canada T0H 1L0
Phone 403-835-2238 Fax 403-835-2185
Study Junior Authors: Lynne Sigler
Sean Abbott
University of Alberta
Microfungus Collection and Herbarium
Devonian Botanic Gardens
Edmonton, Alberta, Canada T6G 2E1
Phone 403-987-4811
For a copy of the full report: (There may be a charge.)
Denis McKenna
Fairview College
Box 3000
Fairview, Alberta, Canada T0H 1L0
Phone 403-835-6633 Fax 403-835-6698
Article Author: Kenn Tuckey
Provincial Apiculturist
Alberta Agriculture, Food and Rural Development
RR 6, 17507 Fort Road
Edmonton, Alberta, Canada T5B 4K3
Phone 403-422-1789 Fax 403-422-6098
Internet: [log in to unmask]
ABA Alberta Beekeepers Association
16713 - 113 Ave
Edmonton, Alberta, Canada T5M 2X2
Phone 403-489-6949 Fax 403-489-3041
Submitted by Joan Tuckey for Kenn Tuckey
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