Document bamKegNw87QrXVwbqDXK158Y1
FILE NAME Synkaloid SYN
DATE 1980
DOC SYN026
DOCUMENT DESCRIPTION 1980 Journal article on asbestos exposure in
drywall taping Citation Verma DK Middleton CG Occupational exposure to asbestos in the drywall taping process Am Ind Hyg Assoc J. 1980 264-9 doi 15298668091424726 PMID 7395743
Studies of airborne asbestos fiber concentrations associated with various operations of the drywall taping process have been undertaken in the province of Alberta Canada The results show that mixing sanding and sweeping created high levels of airborne asbestos dust The measured concentrations were frequently in excess
ccupational health standards Sanding in particular was assessed the most hazardous operation The results are are discussed in light of present and proposed Occupational Health Standards and terms of its implications for other workers household contacts and consumer's risk Measures to reduce and control the health hazards
associated with the process are described
Occupational exposure to asbestos in the drywall taping process
DAVE K. VERMA and CHARLES G. MIDDLETON
Occupational Health Program McMaster University Hamilton Ontario Canada L8N 3Z5
Occupational Health & Safety Division Alberta Worker's Health Safety & Compensation Edmonton Alberta
Canada T5K 2J6
introduction
Occupational exposure to asbestos is associated with a risk
of asbestosis mesothelioma an excess risk of cancer of the
first study may not be indicative of typical occupational exposure of the drywall taping process
lung and possible cancers at other sites These asbestos
related diseases have been found in mines and mills in manufacturing industries and in the use of asbestos products such as insulation in construction industries The
gnitude of the occupational health problem associated
In asbestos exposure is enormous The relative risk of
lung cancer among asbestos workers has been demonstrated from epidemiological studies to range between 1.4 and 3.3
for miners and millers 1.0 to 13.7 for production and manufacturing industry workers and 5.1 to 8.3 for insulators The risk due to cigarette smoking and asbestos exposure has been recognized to be multiplicative rather
than additive so that an asbestos worker who smokes has an
extremely high risk of lung cancers An asbestos worker who smokes has a 92 times greater risk than a worker who neither smokes nor works with asbestos
Very little has been reported in the literature about the potential occupational health risk to drywall taping workers A review of the literature revealed only two
independent studies dealing with the occupational exposure to asbestos in the taping process In the first study results of thirty air samples taken at the various operations of the process were discussed Generally high mean values of 2.6 to 47.2 tibers for specific operations airborne asbestos levels were noted This earlier report has recently been
Data is also lacking on the health status of this group of workers exposed to asbestos One published report of medical examinations conducted on a group of 69 tapers
showed ray abnormalities characteristic of asbestos exposure in 37 out of 69 films Two thirds of this group -
had an exposure of 10 years duration or longer and 61 were
smokers or smokers A recent clinical report on the
same group of drywall workers but with an expanded cohort 114 showed radiological evidence for pulmonary asbestosis in 40.9 of the cases examined This compares to 48.5 among insulators Consequently drywall tapers appear to have similar exposure as insulators In light of this it is interesting to note that tapers in Alberta are not under medical surveillance whilst insulators who are considered asbestos workers are To our knowledge this lack of medical surveillance for tapers as asbestos workers exists in other provinces of Canada and most parts of the U. S.
Because of the above mentioned concerns we initiated in
1975 an investigation in the province of Alberta of the drywall taping process This operation was known to involve the use of an asbestos containing compound
Specifically the aim of this study was to assess quantitatively
the occupational exposure to asbestos in this group of workers Our findings are summarized in this report
published in an expanded version In the second study conducted on a similar sample size much lower mostly
between 0.5 and 3.5 fibers exposure levels were
reported The latter authors inferred that the results of the
the drywall taping process
3
PLAINTIFF'S
a
EXHIBIT Fi -54-12
-54-12
In the construction of a commercial building wallboards
The opinions and suggestions contained in this report are the private
views of the authors and are not to be construed as official or representing the views of Alberta Worker's Health Safety and
Compensation
are fixed to metal studs with screws while in residential houses the gypsum wallboards are nailed onto the wooden
studs The resulting joints as well as screw and nail indentations are finished by taping
Ccouright 1980. American Industrial Hygiare Rasoolation Rasoolation
264
An ing Hyg Assoc J. 41
April 1990
mixing
The dry joint compound powder is normally contained in paper bags The bag is slit open by a knife and the powder dumped into a container Water is then added according to the manufacturer's directions and the compound mixed by means of a portable electric drill equipped with a mud and paint mixer Some joint compound is sold as a paste referred to as premix and only a small amount of water is required The prepared mixture in its putty like form after wetting is referred to as mud The time spent mixing in a working day is short It usually takes 5 to 10 min to mix a batch and in most instances one to three batches are required daily
application
The joint compound mud is placed on the bottom side of a paper tape and is applied to cover the joints between the
gypsum boards and allowed to dry Subsequently this
compound is also applied on the front side of the tape and to screw and nail indentations A major portion 65-70 of
the working day is spent in this operation
sanding
The joints and indentations are sanded between each application of mud with the major amount of sanding being
carried out after the final coat Three to four coats of mud
are usually applied Sanding operations normally involve
either hand sanding or pole sanding Hand sanding is
carried out with a hand abrasive paper covered
operation is sanding block In pole sanding the sanding block at the
end of a long pole Generally speaking most of sanding is
carried out by pole sanding We estimate that 25-30 of
total time is spent in this
=e
sweeping and cleanup
The debris and the dust accumulated on the floor resulting from the mixing application and sanding operations is generally cleaned up by dry sweeping In many instances
especially in cases of commercial building and large
projects this operation is carried out by general laborers
However it was generally found to be part of the work schedule of employees of small companies working on
residential construction projects
the composition of joint compounds
The composition of joint compounds varies from
manufacturer to manufacturer During the study period most joint compounds were said to contain between 3-6 3-6 % of chrysotile asbestos by weight The remainder was
composed of limestone or dolomite talc clay mica starch and fungicide A typical joint compound formulation based on the information obtained from the manufacturers was
Limestone ...................... 80 - 85
Clay talc mica
2...
2.
5-10 5-10 %
Asbestos as chrysotile .............. 3-6
Bea Fungicide Organic material
. Less than %
ee
vinyl alcohol vinyl
ae
acetate starch potassium
polyphosphate etc.
2-3 %
ied
Fan
Although most joint compounds at present contain 3-6 %
Yabo American Industrial Hygiene Association JOURNAL
fly
Si
41 4/80
"322
of asbestos chrysotile in the
past they have contained
much higher proportions of asbestos Three
compounds are available
types ofjoint
taping topping and all purpose
all of which contain asbestos Taping joint compound is
applied in one or two coats and is designed for strength The
topping or finishing variety is generally applied in the final
coat and has better finishing qualities The all
purpose
compound is a compromise formula that can be used for
both taping and finishing purposes Asbestos is used in these joint compounds because it serves several functions
including controlling shrinkage and cracking when the mud
dries and providing good workability in troweling and sanding
materials and methods
site description
During 1975 to 1977 several work were visited throughout the province and eight of them were evaluated
by air sampling Work schedules and the time spent at
various operations at worksites differed widely In small companies the owner often worked out of his home and undertook all the work himself Companies with larger workforces of 15-20 employees had individual workers performing specific tasks such as sanding on a time
basis
Following these initial surveys we conducted a more detailed study over a month period at a downtown site
in Edmonton where a storied hotel was under construction This survey of a large commercial site was
begun in January 1978
Both the residential and commercial site studies concentrated on the evaluation of worker's exposure to airborne asbestos dust The potentially hazardous effects of other components of dust such as nuisance particulates crystalline silica chemicals etc. were not examined in the same detail It was felt that asbestos posed the most significant hazard and control measures applied for asbestos exposure would be equally effective against other hazardous
:
particulates
methodology
1. Airborne asbestos dust samples were taken by using open filter cassettes loaded with 37 mm 0.8 micron pore size Millipore Type AA membrane filters Air was drawn through the filter papers by a
portable pump at a flow rate of 2.0 liters The
sampling period was guided by two factors -
concentrations expected and duration of
operations Most sampling assemblies were attached to the worker's lapels To obtain area or location samples assemblies were attached to
portable stands The pump was calibrated before each use by a soap bubble meter The flow rate was
checked frequently during sampling
2. To determine the concentration of airborne
asbestos analysis of the samples was effected by the NIOSH reference Membrane filter method For
consistency most of the asbestos counting was done by one of us C.M. A very limited number of
265
TABLE I
Summary of Airborne Asbestos Fiber Concentrations in fibers > 5 cc
Encountered in the Drywall Taping Process
Operations Application 2
Number
Samples
10
Sampling Time Min
Range
=
Mean
39 - 65
54.4
Concentrations
Range
0.4 1.3
Mean 0.9
Median
0.9
Mixing 1
Dry Powder
3
10-12
10.6
12.4
11.2
12.2
Mixing 2
mix
7
45
4.6
1.2 3.2
2.4
2.3
Mixing Area 2 mix
7
3
4.0
2.7
2.0
2.0
Hand Sanding 1
22
80
15.0
24.2
11.5
11.5
Pole Sanding 1
20
38
18.5
10.1
4.3
4.0
j
Pole Sanding 2
32
4-21
13.9
1.2 - 10.0
4.6
3.8
Pole Sanding 3
52
4-38
15.7
10.1
4.9
3.8
t
.
Sanding Area 3
10
58
22.0
0.3 7.0
3.2
2.3 -
8 from set )
:
Sweeping 1
6
30
20.7
26.5
12.1
7.7
Sweeping 2
4
20
14.2
25.4
19.6
19.4
;
Sweeping 3
10
9.30
18.1
26.5
15.1
15.5
All operations 1
59
9-80
17.5
26.5
8.0
5.9
All operations 2 62 65 18.5 0.4 - 25.4 4.3 2.7 J
*
All operations 3
121
3-80
18.0
26.5
6.1
3.7
'
The numbers in parentheses refer to the following collection schedules
ane
1 air samples taken at several residential sites throughout the Province of Alberta during
1975-77 2 air samples taken at the Edmonton storied hotel site 3 air samples taken during 1975-1977 and 1978 combined Personal samples were collected
during
1978
Area samples were collected
re
Mer
e samples 10 were either analyzed by ray
concentration were evaluated The results are depicted in
a
diffraction or were subjected scanning electron
Figure 1 and for the taping process as a whole appear to
microscopy for asbestos fiber identification
follow a log normal distribution
3. The data analysis involved the computation of simple descriptive statistics
results and discussions
The results summarized in Table I and Figure 1 are conveniently discussed in detail in relation to each of the four operations of the process mixing application sanding
and cleanup
In Table I the number of samples collected for various operations are given along with range and mean of sampling
time and range mean and median of the observed fiber
counts The data obtained during 1975-77 are designated in this table as set 1 and those obtained in 1978 are identified as set 2 This distinction between the two sets of data was made because as already mentioned set ) was primarily from the residential taping operations and set 2 from large commercial building taping operations However since the joint compound used was similar and the exposure level comparable to strengthen the data base they have been
mbined as set 3 In addition the Low Value L the Lower Quartile 1Q the Median M the Upper Quartile 3Q and the High Value H for the measured fiber
mixing Although the exposure duration of this operation was short concentrations as high as 12.4 fibers were found in the limited number of samples 3 taken during mixing of the dry joint compound powder Concentrations as high as 59.0 fibers cc have been reported earlier
The mixing of the mix compound on the other hand
resulted in much lower exposure of only 1.2 to 3.2 fibe/rese
Considering the short duration of mixing and low exposure encountered the use of mix should not create any significant hazard in this operation
266
An Ind Hyg Assoc J. 41
April 1980
10
M
3Q
ALL OPERATIONS 1 [[*
T
ALL OPERATIONS 2 jf
|]
LL
ALL OPERATIONS 3 [|
H
ma)
J
APPLICATION 2
oO
MIXING DRY 1
MIXING PRE MIX 2 |
MIXING AREA 1
|
HAND SANDING 1
{
__}
POLE SANDING 1 POLE SANDING 2
| ae
_}
CETTrT__]
SANDING AREA [1 [ d
SWEEPING 1
if
|
J
SWEEPING 2
{
!
_j
1
'
'
0
5
15
20
3
30
CONCENTRATION fibers cc
Figure 1 - Observed fiber counts for the various operations in the taping process
The numbers in parentheses ordinate labelling refer to the collection time and
place as explained in footnote a of Table I. L 1Q M 3Q and represent value
the Lower Quartile the Median the Upper Quartile and the High value
respectively
application
.
During application the compound is in the form of a paste
nd virtually no dust should be generated Air samples
taken however indicated concentrations ranging from 0.4 to 1.3 fibers Other studies have not reported fiber
levels during this operation The airborne fibers found were
most likely the residual fibers that were generated in other
operations e.g. mixing or sanding that were carried out
earlier
~
sanding
It can be seen from the data in Table I and Figure 1 that airborne asbestos fiber levels encountered during hand sanding ranged from 2.1 to 24.2 fibers and during pole sanding which is the more prevalent means of sanding ranged from 1.2 to 10.1 fibers There was good
agreement between the median concentrations encountered
during sanding in both the data for 1975-77 and for 1978 see Figure )
Our results which show high concentrations during sanding are in general agreement with the results of one of the earlier studies Levels of 1.2 to 19.3 fibers were reported for pole sanding number of samples - 10 and 1.3 to 16.9 fibers during hand sanding number of samples 11 These and our own results are considerably higher than those 0.3 to 3.5 fibers 29 samples composed of 24 pole sandings and 5 hand sandings reported in the only
ther study Although our results show hand sanding to
produce higher fiber concentrations than pole sanding
other studies have shown the opposite The reason for
American Industrial Hygiene Association JOURNAL
41 4/80
this difference is not obvious but could be due to different
work practices
No mechanical control measure e.g. local exhaust at the
sander was employed The only practical available measure is the use of appropriate respiratory protection Unfortunately the use of respirators by this group of workers was not widespread
sweeping and cleanup In cases where it was possible to obtain samples concentrations of 4 to 26.5 fibers were measured
relation of findings to occupational
health standards
To facilitate the interpretation of exposure experienced by tapers a brief discussion of the present and proposed occupational health standards follows Our own results are subsequently discussed in the light of these levels
The asbestos standards and recommendations in the
U.S. and Canada are constantly being revised OSHA has a
present standard of an 8 hour time weighted average TWA
of 2 fibers cc that are greater than 5 microns in length with a ceiling of 10 fibers cc and it has a proposal to reduce it to 0.5 fibers cc as a TWA NIOSH has recommended the adoption of a TWA of 0.1 fibers with a ceiling of 0.5 fibers cc.ACGIH cc.ACGIH has also published in its intended changes list of 1978 new TLV's for various forms of asbestos
that range from 0.2 fibers cc to 2 fibers
In the Province of Alberta the asbestos standard since
1975 has been a TWA of 2 fibers with a ceiling of 10
267
fibers Some provinces e.g. Alberta and Ontario in Canada are considering adoption of asbestos standards
similar to those proposed by ACGIH in its intended changes
list of 1978
To determine the time weighted average TWA
centrations to which tapers were exposed the following
aula was employed
TWA =
e
4
zCt
rCit
i1 = +
40
Where C is the exposure encountered at job i during the time t employed at this operation A typical taper's work week of 40 h could be broken down into the following
exposures
) h t during mixing with an exposure
concentration of C
ii 27 h tz during application with an exposure
~
concentration of C
iii 10 h t during sanding with an exposure
concentration of C3
iv 1h 1h ) during cleaning with an exposure
concentration of C.
The calculated TWA values differ greatly depending upon
the type of operations used in the above formula Let us consider two situations case ) where mixing was done by employing dry mixing and sanding effected by hand
sanding Case 2 where a mix compound was employed
and the finishing achieved by pole sanding Using the ian values given in Table I and Figure 1 of 12.2
mvers 2.3 fibers 11.5 fibers 3.8 fibers 0.9
fibers and 15.5 fibers for dry mixing mixing mix
hand sanding pole sanding application and sweeping respectively the calculated TWA values are 4.5 fibers for case 1 and 2.1 fibers for case 2
It is clear that the TWA values calculated in the above
manner are generally in excess of the present occupational limit and are far in excess of the newly proposed criteria
Such assessments for the taping process may not be very
adequate in all cases since various factors affect the final
result These include
I Time periods allocated to various operations are only approximates and may vary significantly
II Operations may be performed solely by one individual e.g. a person doing sanding time which was the case in some instances
III joint compound produces a much higher dust concentration than mix compound during mixing
IV The percentage of asbestos found in the
compounds may vary depending upon the
manufacturers
V Some operations e.g. cleaning and sweeping may not be performed by all tapers
ecause of these limitations a single TWA value for all drywall taping processes cannot be accurately assessed
268
Consequently it is our opinion that the exposure data is most meaningful when expressed as in Table I and Figure ,
as the concentrations encountered in specific operations mixing application sanding and cleanup of the taping process from which the TWA for any situation could be
derived
In the U.S. the Consumer Product Safety Commission
CPSC in 1978 banned the sale of asbestos containing compounds to the consumer on the grounds of possible
asbestos related health risks This ban however does not apply to the products made for commercial and industrial use where most of the occupational exposure to tapers occurs In Canada the Department of Consumer and
Corporate Affairs of the Federal Government currently has under consideration a similar 16,17 This Canadian
proposal differs from the U.S. Consumer Product Safety
Commission's in that it may apply to products made both for consumer and commercial markets
conclusions and recommendations
We believe that our results constitute a realistic and
comprehensive assessment of typical exposure experienced
by tapers The data should be useful in planning suitable
health protection programs and in the assessment of past
exposure for such purposes as adjudication of
compensation claims and design of epidemiological studies The essentials of our findings may be summarized as
follows
1 The tapers are occupationally exposed to
potentially hazardous asbestos dust concentrations
in their work The asbestos hazard can be eliminated
by the use of asbestos free joint compound Although asbestos free joint compound is available and most manufacturers are actively working
towards the reduction and elimination of
asbestos in their material most of the taping
compounds used still contain asbestos The use of
asbestos free compound is the only feasible method
of total control of asbestos exposure and is therefore
strongly recommended However a person engaged in mixing sanding and sweeping of asbestos
containing compound should wear an approved
respiratory protective device
.
2 The use of mix compound is preferable over dry powder joint compound because it eliminates high exposure during mixing It is recommended that the amount of joint compound used should be the minimum necessary for the job
3 Sanding is the most hazardous operation of the taping process because the concentrations of asbestos encountered are high and large portion of total time is spent in this operation To reduce the
exposure various control measures should be
considered including the effective use of respirators
and rotation of workers
4 The short term hazard associated with sweeping and cleanup operations could be reduced by employing
an industrial type vacuum cleaner If a broom must
Am Ind Hyg Assoc J. 41
April 1920
be employed a dust suppressant compound should
be used
5 Tapers who work with asbestos containing compound should be included in the medical
surveillance program for asbestos workers
Additional epidemiological studies of this group of workers are also recommended Furthermore
tapers should be familiarized with the potential
health hazards especially the greatly elevated lung
cancer risks for asbestos workers who smoke
6 The unnecessary exposure of tradesmen not directly
involved in taping can be avoided by proper job scheduling and restricting the entry to exposure
areas Contamination of the home environment can
be minimized by careful handling of workclothes and good personal hygiene
acknowledgement
The authors wish to thank Mr. David E. Gibson Director
Occupational Hygiene Branch Alberta Worker's Health
Safety & Compensation for his help and encouragement
during the study Thanks are also due to Mr. Gerry Wunderlich of Alpine Drywall Company and to those
drywall tapers who participated in the study
We are grateful to Mr. Jim Julian Dr. David Muir and
Dr. Evert Nieboer of McMaster University for their help in
the preparation of this report
:
5
references yy
1. National Institute for Occupational Safety and Health Criteria for a Recommended Standard ... ... ... Occupational Exposure to Asbestos U. S. DHEW Cincinnati 1972
2. National Institute for Occupational Safety and Health
Revised Recommended Asbestos Standard U.S. DHEW
Cincinnati 1976
~ wo?
3. Selikoff I. J. E. C. Hammond and J. Churg Asbestos Exposure Smoking and Neoplasia J. Am Med Assoc
104-110 1968
4. Becklake M. R Asbestos Related Diseases of the Lung and Other Organs Their Epidemiology and Implications for Clinical Practices Am Rev. Resp Dis 187-227 1976
5. McDonald J. C. M. R. Becklake G. W. Gibbs A. D. McDonald and C. E. Rossiter The Health of Chrysotile Asbestos Mine and Mill Workers Arch Env Health 6168 1974
6. Knox J. F. S. Holmes R. Doll D. Hill Mortality From Lung Cancers and Other Causes Among Workers in an Asbestos Textile Factory Br J. Ind Med 293-303 1968
7. Selikoff I. .: Asbestos Disease in the United States 19181975 Rev. Jr. Mal Resp Suppl 1 au Tome 7-24 1976
8. Rohl A. N. A. M. Langer I. J. Selikoff and W. J. Nicholson Exposure to Asbestos in the Use of Consumer Spackling Patching and Taping Compounds Science 551-553 1975
9. Fischbein A. A. N. Rohl A. M. Langer and I. J. Selikoff Drywall Construction and Asbestos Exposure Am Ind Hyg Assoc J. 402-407 1979
10. Rhodes H. B. and B. L. Ingails Asbestos and Silica Dust in
the Drywall Industry Part 1 and Part 2. G.D.C.I. Gypsum
Drywall Contractors International Drywall 6-8 1975 1-6 1976
11. Anon Asbestos Risk Exists From Use of Taping Compound Insulation Hyg Progress Rep 2-4 1975
12. National Institute for Occupational Safety and Health Sampling and Evaluating Airborne Asbestos Dust U. S.
,
DHEW Cincinnati 1974
13. TLVs Threshold Limit Values for Chemical Substances and
Physical Agents in the Workroom Environment withintended
Changes for 1978. ACGIH Cincinnati 1978
14. Ray D. .: Personal Communication Consumer Product
Safety Commission Washington DC 20207 December 1978
15. U. S. Federal Register 63354-63365 December 1977
16. Brownstein M Personal Communication Consumer and
Corporate Affairs Gov't of Canada Ottawa Canada May
1979
17. Consumer and Corporate Affairs Canada Product Safety
Branch Trade Communique - Asbestos Containing Products
Issue No. 1. April 1979
American Industrial Hygiene Association JOURNAL
41 4/20
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