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INDUSTRIAL GIENE FOUNDATION OF. ^ERICA.INC.
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Mellon Institute. <4400 Fifth Avenue
Pittsburgh 13. Pa. September 30, 1963
Mr. C. C. Ruddick Pittsburgh Plate Glass Company
1 Gateway Center
Pittsburgh, Pennsylvania 15222
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Dear Mr. Ruddick:
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Enclosed are seven copies of our report on "Evaluation of The'Asbestos Dust Hazard in Tyler, Texas Plant". If you have any questions or comments regarding this work, do not hesitate to call on us. Also, we have several extra copies if you have need of them.
A statement of charges covering these investigations will be submitted at a later date.
Sincerely yours.
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Robert T. P. deTreville, M.D. Managing Director
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dcT:mj Enclosures
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AH ASSOCIATION or INOUSTBICS fO THE ADVANCEMENT Of Hf ALTMfUt 'NCBKIMO CONDITIONS <.
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ifNUUi 1 HiAi . 'UIC.INC. I-UUND AT I O N OF A ' * R ICA, I N C.
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Mellon Institute, 4400 Fifth Avenue
Pittsburgh 13, Pa.
Report on
EVALUATION OF THE ASBESTOS DUST HAZARD
IN, TYLER, TEXAS PLANT
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of the
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PITTSBURGH CORNING CORPORATION
July 8, August 6, 7, 1963
Field Investigation By:
Jacob Cholak Lawrence J. Schafer William J. Schreibeis
Samples Analyzed By:
The Kettering Laboratory
Cincinnati', Ohio
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.William J. Schreibeis, P.E.
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Robert T. P. dcTrcvillc, M.D.
Industrial Hygiene Engineer
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Managing Director
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AM ASSOCIATION Or INDUSTRIES TOR TMC ADVANCEMENT Of HEAUTMruL ImORKINO CONDITIONS
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INTRODUCTION
On July 8, the plant of the Pittsburgh Corning Corporation, Tyler,
Texas was visited by Messrs. Jacob Cholak and William J. Schreibcis in order
to review the potential health hazards of handling asbestos during manufacture of
asbestos pipe insulation. On August 6 and 7, 1963, sampling was conducted at
the plant by Mr. Lawrence J. Schafer and an evaluation made of the airborne
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dust concentrations.
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DISCUSSION OF RESULTS
In Table 1, the concentrations of particulate matter, when possible, are expressed both on a weight basis and as the number of particles present in one cubicjfoot of air. Samples collected with the high volume- sampler and the electrostatic precipitator were suitable for gravimetric and other analysis while samples collected on membrane filters were suitable for dust counting only. The number of particles present in the air as total particulate matter and as asbestos fibers were determined. Any rod like particle with length definitely greater than width was considered as asbestos fiber. It may be seen that the per cent of fibers in the dust varied from a low cm 29% to a high of 56%. The dust in the sawing area contained a slightly higher content of asbestos fibers than did the airborne dust in the production area. It will also be noted that more parti-1* clea of dust and fibers of asbestos were present in the air near the scrap crushers
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than, surprisingly, was the case for air in the sawing area. The values in Table 1 followed by an asterisk are estimated counts taken from the straight lines in Figure 1, fitted to the data by the method of least squares. It may be seen,
';f . 'yithat the dust counts and the mass coneentrations are close! v:.xclated. Figure 1
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offers the plant a rather simple method for estimating the numbers of total
particles and of the fibers of asbestos present per cubic foot of air from the mass
weight data and volumes of air sampled.
Highest dust counts, at the threshold limit, were obtained in the case
of*samplcs collected at the scrap crusher. The highest concentration of dust oc
curred for the five-minute period that the three-unit dust collector in the saw
area was being cleaned. The air at the take-off areas of the building machines
was the least contaminated with dust,
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It should be noted that the threshold limit for asbestos, (5 mppcf) is
assumed to apply only to asbestos fibers while dust in the air of the plant will
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contain other particulates, including filler materials used in the process. Since
some evidence that the most active particles are those fibers between 20
and 50 microns in length, the numbers of fibers present in various size categories
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were also determined. These data are given in Table 2. Data in Table 2 and the asbestos fiber counts in Table 1 were used to derive the data in Table 3. As may ^ be seen from Table 2, the fibers in the air of the sawing area wer&gcnorally
shorter than were those in the process area,
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. In Table 4 arc tabulated the per cent of the numbers of the fibers of
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tt. . asbestos or, more properly, bundles of fibers varying from 5 microns to less *
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than 1 micron in diameter. The fibers in the air of the sawing area appear to
have slightly smaller diameters than was the case for fibers in the air of the pro
cess area,
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The results of other analytical work performed on these samples are
given in Table 5. As may be seen dusts or fibers removed from the air in the
production and sawing arcas/did not contain any free crystalline silica.I Two dif-
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ferent samples of Dacolite contained variable small amounts of quartz and cristoba
lite. in view of the warning printed on each bag, the low concentrations of free
silica in this material were rather surprising.
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It would appear from the analysis of the samples that were collected
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intentionally only at those processes that appeared to be the principal producers
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of dust, that the number of asbestos fibers present in the air,_ with few exceptions;
^were well below the threshold limit of 5 mppef. One significant exception was*
the brief period of time during which a collector system was being cleaned. Dur
ing this period, excessive quantities"or'dust and fiber were being dispersed into
the air for a period of about 5 minutes. It would appear, from an examination of
the total numbers of particles and of fibers as well as observation of the operations
that the crusher and the sawing operation may at times produce large quantities
of dust. However, the dust, because of its physical characteristics, appears to
settle out of the air rapidly. Particles of particulates in samples collected at
breathing level heights, wore well below threshold limits, even though some op- \
orations were observed to produce what appeared visually to be 'large clouds of
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The type of asbestos used in the plant is Mamositen an iron-magnesium
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silicate. The specific gravity of this material is 3, 45 as compared to 2.55 for
chrysotile, the material more widely used in this country.
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The fibers of chrysotile are also much smaller in diameter than are those of amositc, the minimum diameters being 0.5 micron and 0,03 micron | 'xf.
respectively for amosite and chrysotile. Another factor in favor of the rapid , <
settling of the fibers from the air of the plant is that the asbestos bundles are not '
given the drastic shredding as in the textile industry,
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; RECOMMENDATIONS
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At no time during the survey was the air of the plant contaminated
with dust to the point to affect visibility, and one could always see down the entire C '
length of the rather long building in which, the operations were being conducted.
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1, There was an obvious need to institute a better housekeeping pro
gram, especially in the sawing area. Floors, equipment and other structures / should be cleaned regularly and frequently according to a definite supervised '
schedule. Dry sweeping should be avoided and only vacuum cleaning equipment
providcdj*'ith.auitablc__collector8 should be used,
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2. Hoods and ducts should be maintained in good working order and
all breaks and leaks in connecting ducts, etc. should be repaired promptly. k.
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3, The hoods and the exhaust system at the wheel cutter in the saw*
dng room should be improved.
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4. More space should be provided between the sawing equipment to
reduce cross-contamination of the air with dust.
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5, It is suggested that the crusher be fed by means of a short con veyor system in order to keep the operator clear of the cloud of dust produced
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when the machine is in operation.
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6. Operators should be educated in respect to working habits which
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will reduce the dispersion of dusts. For example (a) carts of crushed material should be moved from the crusher_only after the crusher has been turned off and a brief period has elapsed to permit dust to settle, (b) Work should be removed
% from the large slitter only after the exhaust system has cleared the dust from the
interior of the piece being cut. A wait of only a few seconds would accomplish / this, (c) Bag collectors should be opened only when the discharge end of the col
lector is closed.
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Table 3 -- The Numbers of Asbestos Fibers (mppcf) ^Present in the Air According to the Range
. of the Lengths of the Fibers
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Millions of Fibers Per Cubic Foot of Air
5-50 Microns
10 - 50 Microns
in Length
in Length
0.68 0.43 1.50
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. 2.40 0.78 `
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3.06
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0.36
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. 0.67
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' 6.80
1.64 " 0.15
0.14
0.07
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0; 87
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}\ f . Table 5 -- Free Silica Content of a Number-of Sample#
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Collected in the Plant
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Dcscription of Sample
' Per Cent Free Crystalline Silica
Quartz
Cristobalite
Tridymite
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'A sample of Dacolite collected on 7-10-63
,'A.sampie of Dacolite collected . -on 8-5-63
3.0 . 2,5* . Absent
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* General air sample collected in * . -the sawing area between the
.* `large slitting saw and the . ' large edging saw.
<2.0
Absent
Absent
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. General air sample collected 5 feet from the scrap crusher.
General air sample collected in the feed area.
<2.0 <2.0 '
Absent Absent
Absent Absent
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