Document J3ZNdzMZXLwaLLo187G5Kdyka
FILE NAME Owens Corning OC
DATE 1935 DOC OC294 DOCUMENT DESCRIPTION Journal Article - Ruck Wool in Relation to Health
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WASHINGTON D. C.
01 501 0758
Hopriated from THE JOURNAL OF INDi etnial liraISNE Vol 17 No , November 1935
ROCK WOOL IN RELATION TO HEALTH
Lawrence T. FAIRHALL PH.D. STEWART H. WEBSTER PH.D. and GRANVILLE A. BENNETT M.D.
From the Laboratory of Physiology Harvard School of Public Health and the Department of Pathology Harvard Medical School Boston Mass
HE utilization of furnace slags
T in the form of wool for insulation purposes has become so exten-
sive that the former metallurgical by-
product is now manufactured direct
and marketed under various names
such as rock wool mineral wool etc. insulating houses this material
is blown into all spaces in the outer walls and a covering laid down in the
attic so that the house is completely
insulated Since individuals living within the houses are surrounded by
such material it has been questioned
whether the use of rock wool could be a
problem of hygienic importance In-
asmuch as this material enters into construction in such a manner that the
ished product Although the latter is a relatively low silica glass stable insoluble and chemically inert a
searching investigation was made of its chemical composition and of the pos-
sibility of any vaporization of injurious
substances The presence or absence
of any poisonous element would to a large extent establish the material as either dangerous or innocuous completely it is true for assuming a
very toxic combination of certain elc-
ments this combination might escape
detection in the search for the indi-
vidual elements The practical test
therefore was to determine the effect of
the material upon animal life To this
end the following experimental proce-
occupants are separated from it by
plastered walls which act as very effi-
cient filters the only conceivable way
in which it could cause injury assum-
dure was adopted
EXPERIMENTAL PROCEDURE
Cats were selected as experimental
ing harmful ingredients would be by
means of vapor either direct or as a
result of slow decomposition The
animals since they are sufficiently sen > sitive to poisons can be housed conveniently and have tissues sufficiently
following experiments were devised to large for extended chemical investiga-
test this effect
In this investigation all the raw materials entering into the manufac-
ture were examined as well as the fin-
* Received for publication October 15
1035
Our thanks are due the Manville
investigation Company for the materials provided for this In addition to the raw ma-
terials entering into the manufacture of the
rock wool the finished products of three plants geographically distributed as follows
were investigated Manville N. J. Alexan-
dria Ind and Waukegan Ill
263
01 501 0759
261
THE JOURNAL JOURNAL OF INDUSTRIAL HYGIENT 17 no
Hon Three types of procedure wete
followed with the examals exammals One
group cho was exposed to any futne or vapor that could be evolved evolved by passting
ar over the rock wool at room tem
priatur Another group 2 was ex-
posed to air passed through the rock
wool so heated that the air curient
acquired a temperative varying bes
tween 67 and 82 The third
mafen diszont diszont of the rock wood from the vactions sources showed the follow-
ing ments to be present and readily detectable chemically stheon cal-
erum magnesium sodium iron aluJummum sulfur titanium michiganese
and zine
When large enough samples were used 10 gm or more an extreinely
miniute amount of lead could be de-
Si0
40
MgO
K .
N
O
MnO
S.
|
HO
Total
TABLE Cursurya Composition or Vaisius Rock Wools
4 . Na Ce
11 28 37 10 33
98 20 0 28 13 0039 0039 01k
99 969
15:30 219Hi 219Hi 18 33
19 37 0 023 016 0 156
921
20 2393 67 11
952 19 0 028 0.051 17
100 812
7.65 0 30 16 0 025 0123
100 650
R mOeludes 0 110 and T10 B manufactured free
4
i
| per cent
18
:
Od content
\
15
partent 1.08
free
e
per tent
006
group 3 in addition to the same exposure given to 1 were further exposed
for 1 hour daily to a dusty atmosphere of very finely ground rock wool All
these groups received the exposure mis
dicated for 2 months continuously
At the end of this time the eats were chloroformed and their tissues removed removed
for pathological investigation und chemical and spectrographie analysts
Preliminary analysis of the raw
tected of that order of magnitude one
would expect to find in a natural rock and traces of arsenic often con-
sidered questionable could barely be detected by the most refined elwinical
means
In order to minimize dust produe-
tion in the process of manufacture the material is treated with mineral oil a small amount of which remates in the
hed product The chemical com-
Nav 1933 ROCK WOOL IN RELATION TO HEALTHE
2457
position of the various types of rock wool was determined and also the oil content These values are given in
Table 1
If the rock wool is capable of giving
off vapor or fime at room temperature
it would be expected that this woukl be more abundantly evident by direct
distillation Accordingly an glass apparatus was constructed consisting
of a large distillation bulb joined to small glass receivers capable of being closed by means of stop cocks A
manometer was connected in series in order to read the degree of vacuum
attained Except where sealed all connections were made by means of ground glass joints A Hyvac pump
could reduce the pressure to at least mm of mercury The material
tested was the commercial oiled product powdered to facilitate loading into the apparatus The distillation bulb containing 10 12 gm of rock wool was heated by a bath of boiling water
The receiver was was cooled to low tem-
perature by means of a mixture of aleo-
hol and carbon dioxide snow After half hour of distillation a very
small amount of distillate 0.020.05 cc was collected and found to be simply water No oil distilled over
Since under these extreme conditions no vapor other than a trace of water
rould be evolved there is no probability that anything is likely to be evolved under ordinary conditions of
commercial or domestic use
1. THE COLD VAPOR EXPERIMENTS EXPERIMENTS
In order to determine further
whether any vapor inimical to animal life could be evolved from rock wool
at room temperature animals were
made to depend solely upon air that
had been in contact with rock wool To this end an apparatus was constructed which is shown in section in
Fig 1. The metal cylinder was 4 ft high and 1 ft in diameter with spun
ends and locked seams The orifices
at top and bottom measured 13 inches in diameter A screen separated the
F10 Cold vapor cylinder rock wool from the bottom so as to insure an even distribution of the air
blown through the lower opening The cylinder held 20-25 pounds of rock wool depending upon the degree to which it was packed Air was blown
through at a velocitoyf 3.3 to 4.5 cu ft
minute The animals siniply lived in this atmosphere and were watched
01 501 0760
266 THE JOURNAL OF INDUSTRIAL HYGIENE 17 no 6
for weight changes or other effects of their environment At intervals of 3 weeks the rock wool was changed so
that the animals were exposed to all
three types The eight cats receiving
this exposure were chloroformed at the end of the 2 months and their tissues
rock wool when filled It was exter-
nally beated electrically by means of winding of nichrome resistance wire Fig 2 Air was blown through at
the rate of 9 cu ft per minute The
air leaving the apparatus at u tem-
perature of 67-82 was obviously too
po a
wa
a
|
ab.
ee eee
=
FIG Hot vapor cylinder a
Nov, 1935 ROCK WOOL IN RELATION TO HEALTH
267
which the animals were kept was small and wholly dark except at such times as when cleaning feeding and weighing were carried on Furthermore in spite
of liberal rum of cooling wattheerorom
was noted The animals remained
healthy and normal throughout the experiment At the conclusion of the experiment they were chloroformed
and their tissues examined as in the
-35cm -35cm
46cm 9 35cm35cm
-35cm L- HOLE FOR AIR SAMPLING
es ANIMAL DUSTCABINET
ELECTRIC HAMMER
30cm
MOTOR DRIYEN INTERRUPTER
KILOGRAMS |\i
WEIGHT
24 5 6 7 99 10 11 12 13 14 15 16 17
EFFECT OF ENVIRONMENT UPON THE AVERAGE WEIGHT OF CATS DURING TWO MONTHS EXPOSURE
Fia Weight changes during the experimental period
removed for chemical and pathological
examination
II THE HOT VAPOR EXPERIMENTS
The apparatus used for heating the rock wool was a metal cylinder 7 inches in diameter and 4 ft in length
the air tubes at either end were 1 inch
in diameter It held 10-12 pounds of
hot to breathe and was therefore
passed through a coil of copper tubing immersed in running water and was thereby brought down to a temperature slightly below outside room temperature The animals were confined to this atmosphere for 2 months successive lots of rock wool A B and C being used The space in
Fia Dusting apparatus
became unpleasantly warm and humid during especially warm days These animals were therefore subjected to rather severe conditions The slight weight loss indicated in the chart Fig 3 is therefore not surprising Beyond this however no other effect
previous case for any significant changes
III THE Dusting ExpenRIMENTS
The eight animals exposed to the
rock wool dust for 1 hour each day 5-6
days per week were incidently exposed
01 501 0761
6 208 THE JOURNAL OF INDUSTRIAL HYGIENE 17 no
during the reminder of the time to the conditions ni group The cats
were exposed in groups of four at a
time in the appar dus shown in Fig 4
Compressed air freed from the slight
moisture usually present by passing over calcium chloride was forced
through the rock wool which had been repeatedly extracted with carbon tetrachloride and then finely ground in
ball mill It was found to be rather
difficult to produre dust with the com-
COUPON The average particle size of
the floating dust after allowing the
coarser material to settle for a few
minutes was 22 Impinger samples of a fixed volume 5 cu ft of air were
taken during the dusting The distilled water suspensions thus ob-
tained were evaporated to dryness in platimuum dishes and weighed The
dust content in terms of milligrams per
cubic meter is shown in the chart
Fig 5 No attempt was made to
800
METER
METER
we
METER
CUBIC
CUBIC
CUBIC
MILLIGRAMS
MILGRAMS
I
aodMILGRAMS Hf
MILIGRAMS
Fa
YJ
10
|
=
bd
_
tf
CW
_
~
f
.
50
60
70
Fig Dust concentrations during the experimental period
mercial type of oiled rurk wool no mat-
ter how finely ground | Furthermore
what dust was carried into the air
remained in suspension a very short time only and quickly settled out The cal very effectively prevents dust formation When repeatedly X-
tracted with carbon tetrachloriadned
thoroughly died however a very satisfactory dust was produced which remained in suspension reasonably well Although finely ground the particle size vaned considerably of
keep the dust at constant constant level on
the contrary every effort was made to
make the conditions extreme by running the dust content to high levels
The animals were exposed to the vari-
ous types of rock wool in turn af intervals of 3 weeks The sole purpose
of the dusting experiment was to deter-
mine whether the rock wool contained
any poisonous substance that had escaped detection by other means
Since as noteil later the only evidence obtained was of a negative character
Nor, 1935 ROCK WOOL IN RELATION TO HEALTH
269
and because of the difficulty we ex-
perienced in raising dust from it one
may fairly assume that dustiness in commercial utilization of rock wool is distinctly a factor of no hygienic importance Throughout the experi-
ment the animals remamed in excellent condition At the conclusion of the experiment their tissues were removed as in the other cases for further ex-
amination
DISCUSSION DISCUSSION
Chemical investigation failed to disclose any single factor of toxic importance From the raw materials including slag limestone sandstone and
oil to the finished products including both oiled and treated rock
wool nothing but | spectrographie
traces of any elements of toxic signifi-
cance could he found and these traces
obviously are fixed in the form of sili-
cates and are therefore most inert The small amount of oil left in the rock wool is also inert except that it has
the valuable property of increasing the filtering action of the rock wool with respect to dust Not only is it difficult make a cloud of dust by blowing air through the ground up commercial rock wool but the rock wool of itself constitutes a filtering medium
In order to test this runs were made
both with the normal rock wool and with rock wool that had been heated
for a mouth and largely dried out The velocity of the flow through the latter was three times that through the
rock wool at rooth femperature The
heated cylinder No. ) was operated
18 hours before testing the room teni-
perature cylinder No. 2 was operated
We are indebted to Mr Richard Page for the dust concentration measurements
for 1 hour before testing The air
flow through cylinder No. 1 was 9.9 cu ft per minute that through cylin-
der No. 2 was 3 cu ft per minute The temperatures were as follows
C.
Compressed air
Corridor air
:
Air leaving ) Air leaving Cyl 2 Experimental Room
_
32
71 vee 2. 27.5
. .. 33
Two samples of the compressed air
one of the corridor air and one cach
of the air leaving the cylinders were
collected The dust concentration
meusurements were made by the dark
field method The results of the
counts and the calculation of the con-
centrations are as follows
Sample
I 2 3 4 5
Description Dual concentration bark peld
particles per cubic foul
Cylinder No .. 58,300,000 Compressed air . 41,600,000
Cylinder No. .. 18,300,000
Compressed air . 45,000,000 Corridor air . 28,000,000
That there is a slight increase in dustiness of air going through the heated cylinder is probably owing not
only to the high velocitoyf the air but
also to the fact that the filtering action was probably reduced by the oil having been largely dried out by the continu-
ous heating during the preceding
month
There is a definite filtering action
apparent in passing the air through the cylinder at room temperature at the lower velocity of 3.3 cu ft per minate That is there is a drop in number of dust particles from the mean value of 43,300,000 particles per eu ft in the compressed air to 18,300,000 partieles per cu ft on leaving the cylinder
With respect to the effect of the rock
01 501 0762
Thi JOURNAL OF INDUSTRIAL HYGIENE 17 no 6
2
en ce ---
---- 1
ver
TABLE TABLE 1
axertopsen FLOAT B
a
Weight
Arsebut Arsebut
1 Mercurs | Jead
Cald vapor 115
e
a
ve
..
2313 2313 100 80 60 1 223 . Mil
| 15 29
Questionable Questionable
Questionable Ver 98 10
Ivaney 4 15 | Nil
= 19 Yer 29 20
40
9102791027
Liver Kade
19 17 OF
Tuch Sidney
8910 26 10
Questiomobh- QuestiomobhNil
NilQuestionable Questionable
Nd
Not
Ni
Ni
Nil Nil
Nil Nil
y Nil Nil
Nil Nil
Nil Nil
Nil Nil
Nil Nil
Nil
Ni
y Nil Nit NO 3 19 k 109 9 32 30 fang IN
| | Nil =
Liver 106 941 slicizumable
Nil
| | Judney 31 25 Nd
Nil
NB
g 22 16:25
8 70l Lang 15.63 Nil
Nit Nil
|| | fiver 72 Questionalde Nil Nil
| Isidney 19 GIF Nil
Nil Nil
| NatNil 15 30 25 93 21 10 Jung 20 Nit
| Inver 90 0 Questionable
Jidney 23 ^ | Nil
Nil
Nil
2 21 21.55 6521 75 Lung 22 No Nil
Nil Inver 83 Questionable
|| Kadney 23 10 Ni
No
11 33
Na
2175 Lung
Nal
Na
| |
Laver 98.70 98.70 Questionable No
Kahney 35.60
Nil
| |:
Nil
Nil
Nil
Nil
Nil Nik
Nil
Nit
Nit Nil
Nil
=
Hol vapor cats
3
89 34
15 20
Jung Liver kidney
2125 2125 Ni 86 Nil
|| 95 Kil
b | 83872910 20 25 85 83872910 83872910 Lang 23 Ni LINE 83 No || hasnes 27 00 Nil
21 | D Ss SO
35 10 81 23 RO
ee eee Dees
Lang Liver
Kidney
33 05 Nd 81 | Nil 22 00 Nil
[| Nil ene
Nil Nil
|| Ni Nil
Nil Nil
Nal Nal Nil Nil
Nil Nil
Nil Nil
NNiill | NNaitl
Nor 1933 ROCK WOOL IN RELATION TO HEALTH
271
_
~
TABLE Continued
Tor Tins fa
eNaLTOEs Fy flea es
BER Lung | Ilver | Kidney Weight uses
Armente
a
Agr
10 | 5
Hot vapor
Concluded Concluded
xhams grams| oF 05 ) 134 54
TGIF
Lung 130 28 | Nil
Liver 130 90 Nil
Kidney 05 | Nil
5 | 29
30
88 29 73
= | Lung 2270 Nil
Liver 85-55 85-55 Nil
Kidney 28:00 } Ni
| 88 05 || 22 29 70
25 Lung 20 Nil Liver 85 80 Ni
Kidney 00 | Nit
17 | 22
25.00
22
Lung
Liver
Kidney
23 Nil
|| 68 60 Nil 23 | Nil
18 | 34
27.50 27.50 | 103 70 80
Lung 75 Nil
|| Liver 101 80 Nil
Kidney 55 | Nil
| Meteurs | Land
Nil Nil
Nil Nil Nil Nil
Nil
Nil
Nil
Nil
Nil Nil
Nil Nil
Nil Nil
Nil Nil
Nil Nil
Nil Nil
Nil | Nil
Nil Nil Nit Nil
Nit Nil
-
21 | 20 | 35
Dusting experiment
67 45 | Lung = 16 25 | Nil Liver 64 30 | Nil
Kidney 40 | Nil
12 1.7 22 61 70 15.65 Lung 20 | Nil Liver 61 60 | Nil Kidney 14.45 | Nil
4 20 17.55 30 25 Lung 15 63 Nil
{ = || Liver 7670 7670 Nil Kidney 20 | Nil
8 [ 11 | 22
GO 16 70
Lung
Liver
Kidney
20 00 Nil
| 57 35 Nil || 15 Nil
13 11 | 12.50 05 13 25 Lung 11.50 | Nil
Liver 40 Nil
|| Kidney 11 65 Nil
1 5 35 35 Lung 90 {| Nil
Liver 64.95 Nil
|| Kidney 21.10 Nil
ee
Nil Nit Nil Nil
Nil Nil
Nil Nil Nil Nil Nil Nil
Nil Nil Nil Nil Nil Nil
| Nil Nil
Nil
Ni
Nil Nil
Nil Nil
Nil | Nil
Nil Nil
Nil Nil
Nil Nil
Nil Nik
01 501 0763
272 THE JOURNAL JOURNAL OF INDUSTRIAL HYGIENE 17 no 6
TABLE II Canlub I
_ :
WHY WHY on TIMEA TIMEA
U8 RATA TESA rd
| theme | | Lever ee
awe
Koken
Wright and i
Mercury end
~
~ 13
Dusting experiment Concluded Concluded
cae
rama
Lung Liver Kidney
172 172 ZZZ
| 75 Nil || 05 ZZZ
ZZZ 32 7 95 83 05 27 10 Lung 19 05
| Laver 85
Kidney 25 2
Ni
Na Ni
Nil Nil Nil Nil
Nit Nil
wool on animal life nothing whatever
was evident that could be construed as
injurions The animals either retained their weight or showed an increase in weight with the exception of
slight traces of arsenic found were balanerd by the trace of arsenic in the nitric acid used in ashing
MICROSCOPIC EXAMINATION OF TISSUES
those subjected to air passed through
heated rock wool and as has been noted above the slight average de-
crease in weight particularly during the last 3 weeks is probably largely
owing to the trying living conditions of temperature and Innuidity to which they subjected At the time they were chloroformed the animals looked healthy and macroscopic macroscopic inspection of
their times on removal showed noth-
ing unusual After chloroforming the cats their
tissues were weighed at once before and
Microscopic sections were prepared
from the lungs kidneys and liver of
each cat used in these experiments and
from four normal control cats In the
experimental animals the tissues were
all fixed in Zenker's fluid embedded in paraffin and the sertions were stained with cosin and methylene blue Tis-
sues from the control cats were fixed
in Zenker's fluid and also in 10 per cent
formaldehyde and paraffin sections sections were stained with methylene blue
and hematoxylin and eosin
after removal of pieces for microscopie
examination and the remantler ana-
lyzed chemically for arsenic mercury
and lead chemicaly For this purpose the tissues
were wet ashed by means of nitric acid in order to prevent any possible loss by volatilization of arsenic and mer-
cury The data thus secured ure given in Table 2. It will be noted that the
results are wholly negative No for-
eigu metals of chemical significance were present in the tissues The very
Cold Vapor Experiment
Microscopic examination of the lungs liver and kidneys showed no constant changes from the normal The lungs from 5 of the 8 cats used in
this experiment showed varying de-
grees of congestion In the three uni-
mals Nos 23 and 14 in which con-
gestion was most marked there were also slight to moderate amounts of
hemorrhage in the pulmonary alveoli
Nov. 1935 ROCK WOOL IN RELATION TO HEALTH
273
The bronchi and bronchioles of all animals contained small amounts of a
staining coagulum that had the histological appearance of mucus In three cats the larger bronchi contained considerably larger amounts of this
material than was observed in sections
from the control animals Slightly ex-
cessive amounts of desquamated epi-
thelium and cellular d^'bris were also
present in both large and small bronchi specimens Occasional groups of mononuclear phagocytes were observed in the smaller bronchi and
bronchioles of all animals Although
many of these cells contained very fine
dark brown or black dust particles it
was only in two animals that rare refractile particles of silicate could be detected Slight emphysema was ob-
served in most animals and in three of
the eight cats there were small amounts
of peribronchial inflammatory cell in-
filtration These abnormalities were also observed in the control animals
Sections of the kidneys and livers
lungs from two cats showed slight
traces of connective tissue increase in
scattered areas The most extensive of these lesions was located in the
periphery of the lung beneath a moderately thickened pleura The
entire area was infiltrated with mod-
erate numbers of lymphocytes niononuclear leucocytes and occasional poly-
morphonuclear leucocytes In the re-
maining areas there were no signs of
active inflammation No particles of
silicate were detected in any of these
areas or in the surrounding lung
tissue and there was no evidence of
associated foreign body reaction
These areas were interpreted as healed
or healing inflammatory lesions prob-
ably initiated by pulmonary infection
Occasional bronchioles contained small
groups of mononuclear phagocytes
which contained small amounts of
dark brown or black pigment Silicate particles however were observed in only one animal In this instance a rare particle was found after pro-
showed no abnormalities that were not observed in the control cats
longed search Sections from the kidneys showed
Hot Vapor Experiment
no significant abnormality
Sections from the livers revealed
Sections of the lungs of these ani-
mals were practically identical in histological appearance to those in Group I. Excessive mucus desquamated epi-
thelium and cellular d^'bris were ob-
served in the large and small bronchi of
no lesions except in Cat 5. In this
animal there was a moderate amount
of chronic periportal inflammation
throughout the organ The liver cells
however were well preserved and there
was no evidence of bile stasis
two cats The lungs of two animals showed recent hemorrhage into pul-
Dusting Experiment
monary alveoli In sections from one The most significant difference in
of these animals and in sections from the lungs of this group of cats as
two other cats there was also fresh compared with those already de-
blood within large and small bronchi indicating that a terminal aspiration of blood was the probable method of spread to the alveolar spaces The
scribed was the presence of large numbers of refractile particles of silicate in the small bronchi bronchioles and alveolar ducts of all animals
ac+me
01 501 0764
274
THE JOURNAL OF INDUSTRIAL HYGIENE 17 no 6
Smaller amounts of this particulate
SUMMARY OF MICROSCOPICAL
matter were observed in the alveolar
EXAMINATION
spaces and interstitial tissues Re-
gardless of its location much of this foreign material was contained in phagocytic cells Many of the small
bronchial passages were filled with
clumps of macrophages cach contain-
ing large numbers of varying sized
particles of silicate in addition to the
fine durk pigment observed in + cats
from the other experimental groups
With the exception of the presence of numerous particles of silicate the lungs of five of the eight cats showed no abnormalities not present in the
previous groups of animals In the
three remaining cats there were vary-
No pathological change that could
be attributed to the experimental
environment was observed in the liver and kidneys of any animal The
renal epithelium of the proximal con-
voluted tubules of 11 cats five from
Group I four from Group II and two from Group III showed slight to moderate degrees of vacuolization Because 2 of the 4 control cats showed
equal or greater amounts of vacuoliza-
tion and because there were no accom-
panying signs of retrograde changes in the tubules and no glomerular
lesions this finding was not considered
ing numbers of small circumscribed lesions that consisted for the most part of dense accumulations of large oval
and elongated mononuclear cells lymphocytes cosinophiles and scat tered polymorphonuclear leucocytes The alveolar walls at the periphery of some of these lesions were moderately
thickened and infiltrated with mono-
nuclear and polynuclear inflammatory cells Siliente particles could be found readily in the majority of these lesions
Four of the cats showed a recent and
probably terminal extravasation of blood into the bronchi and pulmonary
alveoli Excessive mucous secretion
and an increased desquamation of bronchial epithelium were observed in two cats These abnormalities how-
important
Examination of the lungs from cats
in Groups I and II revealed no constant changes that were considered significant The slight to moderate
excess secretion of mucus in the bronchi and bronchioles and the increased
epithelial desquamation which were
observed in few cats were not accom-
panied by any evidence of inflamma-
tion of the bronchial walls or peri-
bronchial tissue Hemorrhage into the lungs was ob-
served in a few cats from all experi-
mental groups and in one of the four
normal control cats The microscopic appearances clearly indicated that this extravasation of blood had oc-
curred as a terminal event probably
ever did not differ from those ob-
served in the other experimental
groups
Histological examination of the kidneys and livers showed no noteworthy abnormality
during chloroformization Examination of the lungs of cats
which had been subjected to the ex-
cessive dusting described earlier in
the paper revealed that large amounts
of silicate particles had been inhaled
Nov. 1955 ROCK WOOL IN RELATION TO HEALTH
275
and retained in the smaller air passages
and lung tissues In 3 of the 8 cats from this group there were varying
numbers of small cellular lesions in
which silicate particles could be de-
tected Except for the presence of silicate particles the remaining 5 cats revealed no abnormalities that were not present in animals from the other experimental groups The absence of spread inflammatory changes in the lungs of all of these animals where silicate particles were in in-
timate contact with the tissues sug-
gests that no highly irritating sub-
stance was present
SPECTROGRAPHIC EXAMINATION
In addition to the chemical analyses an aliquot portion of the ash of each
tissue was examined spectrographically by means of a Hilger quartz spectrograph with the following results
Arsenic most sensitive line
for arsenic is 2319.8 It can be seen
only very faintly if at all in any of the tissues Mercury apparently is not present in any tissue Loud The typical lead line is extremely faint in all cases with the exception of cat kidney No. 5. In this case other lead lines can be found readily to
confirm the first line The other
tissues of this eat show a very faint
no lead line The lead in the kidney
of this cut is doubtless due to some
previous expositre otherwise some
other of the 23 cats subjected to
similar conditions would have exhibited similar effects Thallium is
absent Cadmium is very faintly pres-
ent in most cases No certain indi-
cation of Antimony is given owing to
the presence of iron and traces of silicon
The above metals representing those
commonly met with to which may be
ascribed any toxic significance are so faintly marked in general that they
may be considered of quite negligible
importance Indeed there is no reason to consider them of hygienic significance since these metals when present in the original rock wool are
present in spectrographic traces only
and furthermore are in the form of silicates and are therefore inert
SUMMARY
The chemical data thus obtained
entirely deny the existence of any hygienic hazard in connection with
contact with commercial rock wool of
the type investigated The histological examination of the lungs liver
and kidneys revealed no constant or
significant pathological changes In
the dusted cats there was evidence of
inhalation of considerable quantities of silicate and the accompanying changes in the lungs were those which one might expect such foreign matter to produce
01 501 0765
plehee.
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ma *:
asad HAZRDS
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