Document JJXK5R5z1mrxrn9XBjqdmgLqO
FILE NAME Talc TALC
DATE 1979
DOC TALC021
DOCUMENT DESCRIPTION Conference Presentation from Dusts &
Disease Conference - Mortality Among Miners and Millers of Non-
Asbestiform Talc
378
BOUNDY AL
REFERENCES
Brown C.E Talc In Brobst D.A. and Pratt W.P. (editors) U.S. 1973 pp 619-625
Mineral
Mineral
Washington
Resources Washington D.C.
J.W. Goldin Cares
A.S. Lynch J.J. and Burgess W.A The Determination of Quartz in Airborne Granite by Infrared Spectrophotometry Am Ind Hyg Ass J. 34 298 1973.
Respirable Dust Hildick G.Y The Biology of Talc Brit J. Ind Med 33 217 1976
Jacobs E.C Talc and the Talc Deposits of Vermont Ninth Report Vermont State Geologist 1914 pp
Antique
Deposits
Jacobs
E.C
The
Talc
and
VerdVeerde
Antique
Deposits
of
Vermont
Report
Vermont
State
Geologist
Geologist
1918
232-281 232-281
Leidel Evaluating Leidel
N.A. ,
Bayer SS. .GG..
and
Zumwalde ,
R.RD.DUSPHS NIOSH
Filter
MembraneFiFliltterer
Method
for
Evaluating
press Airborne Asbestos Fibers in
Weiss B. and Boettner E.A Commercial Talc and Talcosis Archives of Env Health 14 304 1967
MORTALITY PATTERNS AMONG MINERS AND MILLERS OF ASBESTIFORM TALC
Preliminary Report
Sherry G. Selevan and John M. Dement
Industry Studies Branch Division of Surveillance Hazard Evaluation and Field Studies National Institute for Occupational
Safety and Health
Joseph K. Wagoner and John R. Froines
Occupational Safety and Health Administration U.S. Department of Labor Washington D.C. 20210
INTRODUCTION
Industrial and consumer applications of talc and associated minerals are widespread Talc is used in such industrial applications as fillers in asphalt paper rubber ceramics paints and plastics Also uses include various dusting applications to prevent adhesion and as a parting agent in molding operations Consumer
a applications include its use as filler for pills tablets as a cosmetic talcum and in -
some countries as a coating for polished rice Blejer and Arlon 1973 U.S. Dept. of Int Bur of Mines 1975
A dichotomy has been identified in the classification of talc asbestiform talc including anthophyllite tremolite and chrysotile and asbestiform talc Early studies do not recognize this dichotomy and the potential for differing health
effects
The first reported case of talc pneumoconiosis was described by Thorel 1896 Since then studies of asbestiform talcs have repeatedly shown their association with progressive pneumoconiosis both among miners and millers Dreesen
and Della Valle 1935 Porro et al 1942 Siegal et al 1943 Kleinfeld et al 1955
An increased risk of respiratory tract cancer among miners and milters exposed to talc containing anthophyllite and tremolite has also been demonstrated Kleinfeld et al 1967 Kleinfeld et al 1974
Until only recently there has been a paucity of epidemiologic data about workers exposed to talc free of both asbestiform minerals and significant quantities of free crystalline silica Studies of industrial populations exposed to these talcs present conflicting results In Italy workers exposed to such talcs both during its extraction and industrial use demonstrated a pneumoconiosis diagnosed by roentgenographic evidence that was reported to affect neither respiratory function nor working capacity Maranzana et al 1963 Scansetti et al 1963a Scansetti et al 1963b Subsequently a mortality study by Rubino et al 1976 found that miners exposed to similar ores demonstrated an increased risk of pneumonconiosis mortality which the authors attributed to exposure to crystalline silica However Fine et al 1976 in a sectional study of rubber workers performing dusting operations with talc low in asbestos fiber and free silica content demonstrated progressive
decrements in pulmonary function associated with increasing duration and magni-
380
SELEVAN AL
Other authors had previously suggested such a possibility based on case reports
only Millman 1947 Seeler et al 1959
As a result of unanswered questions concerning the toxicity of talc free of both asbestiform minerals and significant quantities of free silica the National Institute for
Occupational Safety and Health undertook an industry study cohort mortality
study industrial hygiene study and sectional medical examination of Ver-
mont talcs meeting these criteria i.e. low free silica and no asbestiform minerals
This report contains an assessment of mortality patterns among the cohort exposed
to this talc
MORTALITY STUDY
Materials and Methods
Selected for study were all male Caucasian talc workers who had been radiographed as part of the Vermont Health Department's annual surveys initiated in 1937 of workers in the dusty trades Out of this group workers who met the following criteria were included in the study cohort ) workers were included who were employed in the Vermont talc industry between January 1 1940 and December 31 1969 and 2 were employed a minimum of one year before December 31 1969. Five companies in three geographic areas were studied two of these companies ceased operations in 1952 and 1960. Follow of all study group members therefore was from the time of the initial radiographic examination as a talc worker the date when twelve months of employment was achieved or January 1 1940 whichever was later and was continued through December 31 1975
Occupational and demographic data were obtained from the survey records of the Health Department and companies to permit vital status follow Company records were only used to supplement Health Department work histories when the latter were found to be incomplete
Vital status ascertainment of the members of the study cohort was determined through December 31 1975 by means of records maintained by federal state and local agencies This included sources such as the Social Security Administration state vital statistics offices and state motor vehicle registration files For individuals not located through these data sources other data sources such as city directories post office mailing correction services and other local records were used
As a result of this follow program only 1.0 Table ) of the study cohort 4
of 392 workers was lost to observation Death certificates were obtained from state vital records offices for those known to be dead and causes of death were in-
terpreted and classified by a qualified nosologist according to the Revision of the
International Lists of Disease and Causes of Death in effect at the time of death
These codes were subsequently converted to the 7th Revision For analysis the total study cohort was examined and later was classified into
two work areas milling 225 workers and mining 163 workers The worker was required to have a minimum of one year exposure in the area to qualify for inclusion These two groups were not mutually exclusive seven workers 12 of the
total population qualified for inclusion in both groups
A modified life table technique was used to obtain person of observation by year calendar time periods year age groups year exposure groups and year latency groups Latency is the number of years since onset of initial emplov-
MORTALITY PATTERNS AMONG MINERS AND MILLERS
381 381
TABLE 1. Vermont Talc Study Cohort Status as of December 31 1975
Known to be alive Known to be deceased
Death Certificate obtained
Death Certificate outstanding
Not known to be deceased
Study Cohort Members
No.
%
298
76.0
90
23.023.0
85
21.7
1.3 5
1.3 1.3
4 oe
1.0 1.0
392
100.0
basis
cohort and the number expected on the basis ooff sex age race calendar time and
mortality rates Since many occupational cohort mortality studies
specific was have used U.S. rates for comparison this group used in this study However Vermont rates for the causes of death of interest in this study malignant
expected respiratory disease and respiratory cancer deaths are greater than the U.S.
Therefore comparisons were made for these causes of deaths with those expected
Vermont using
rates specific expected deaths
aplying
obtained
tallies studypopulationcensus of obtained
by
applying
death
rates
calculated
from
yearly
tallies
deaths
observation
of data to the person of observation
the cohort cohort members The yearly deatdeahthss
Statistics
data from 1940 the from the U.S.
to 1967 were obtained the yearly Vital Statistics of
United States National Center for Health
extrapolation
linear using
Statistics After 1967deathsdeath data through 1975 timated using a linear extrapolation for all causes of obtained obtained from all years from 1949
death
Office
from the Vermont Office ofof
obtained
Statistics . U.S. and Vermont population estimates
Vital decenial were obtained fromthe decennial data of the Bureau of Census U.S.
Department of
.
linear
inter-
using
midpoints Department of the year calendar periods were estimated using linear inter-inter-
determined 1958 polationpolation
Statistical significance tailed was
Expectation
Poisson
Variable
"
the Expectation of a Poisson Variable Pearson etal ,
Limits
Confidence
using
Confidence
Limits
for
).
examined
In
to the preceeding analyses other relevant data were
addition examined The Department most recent radiograph taken for the Vermont Health
annual
surveys was obtained for workers dying of malignant
disease and
for
read respiratoryconsultants pneumonoconiosis by a member of the panel of radiology
of
using the Cincinnati classification of radiographic
of
blindappearanwciteh 1/0of cause death pneumoconiosis These radiographs 14 by 17 were read that is
knowledge of exposure to talc or the underlying
of
Readings of
or
higher were considered consistent with pneumonoconiosis
Results
As shown in Table 2 a total of 90 deaths occurred among all talc workers from
January datermined 1940 through DecemberDecmber
with December 31 1975 as contrasted 77.32 expected December statistics patterns The distribution of these
TABLE 2. Number of Expected and Observed Deaths by Cause
by
Among Vermont Talc Workers 1940
Through 1975
Cause of Death ICD No. 7th Revision
Heart Disease 400-443
All Malignant Neoplasms 140-199
Respiratory 160-164160-164 Total Malignant Respiratory Disease 470-527
Influenza and Pneumonia 480-493 Other Malignant Respiratory Disease
470-475 500-527
Other Known Causes Unknown
All Deaths
SMR
Based on 7682.6 person
0.01
Observed
29 16
6 112
0
Expected
US
32.92
12.79 3.69
3.67 1.89
112 25
25
90
1.79 27.94
77.32
116
cohort occurred in the malignant respiratory disease category This
11
observed versus 1.79 expected was specific for other malignant reexscpeirsastory
disease excluding influenza and pneumonia ONMRD
more detailed analysis of specific mortality by working groups is shown
in Table 3,,The mortality patterns observed in this table show that the excess of
total malignant respiratory disease mortality and more specifically ONMRD
mortality occurs primarily among thosethose in the milling group ONMRD 7 observed
versus 0.89 expected
significant increase in respiratoryrespiratory cancer mortality was observed only among
miners 5 observed versus 1.15 expectedexpected No difference of consequence was
noted the other group
respectively Vermont's death rates for malignantmalignant respiratory disease and
cancer are greater than corresponding ratesrates for the entire U.S. Vermont dreesaptihradtaotray
were only available back to 1949. ConsequentlyConsequently the person of observation
from 1950 through 1975 calculated inthe life table analyses described above were
applied to death rates of the United StatesStates and Vermont to obtain
for the study population during that timetime period The patterns of stateixsptieccatlleydsidgenaiftihcs-
ant excess mortality were maintainedmaintained in this comparison The expected numbers of
deaths for Vermont and the U.S. for ONMRD in millers are 1.33 and 0.86
tively versus 7 deaths observed 0.01 for both The number of
respec-
deaths expected in the miners was 1.22 and 1.09
respiratory cancer
and 0.01
versus 5 deaths observed 0.05
If the excess observed of malignant respiratory disease deaths in millers
was a result of talc exposure some confirmation of this relationshiprelationship could
obtained by examining chest radiographs of these workers relationship could be
These data do not tally with those listed in TableTable 2 due to the
and miller
overlap caused by the definitions of miner
MMoorree
.67 .56
1.15
or
Year Expectd US 1.24 4.18
1.23
9.93 26.58 128
One Miners
Employed
in
Observd Employed
Milers
12
34
1.96 and
and .83 .89
Expectd 15.7 Miners
6.28 1.72
Miners
Talc
13.8 37.15 118
Milers
Vermont
Among Observd 16
Among
R
7+
15
Cause
by
Deaths
DDeeaatthhss
Expected
Expected
Expected
1975
Revison and Death
and
480-93 of 7th
Respiratoy 140-9 Through Cause1940 No. Observed
Respiratoy Pneumoia person Observdof Area ICD
160- 4 Number
Neoplasm Respiratoy Malignt Malignt 40-43 470-527 470-5 Disea WorkNumber to 3.
Acording Malignt TABLE
Heart All
Disea Disea
years
person
and 50-27 Cause 4128.5 2865.4
Influeza Other
Known
Other
Unkow
SMR on on
Deaths BasedBased 0.50.1
Total
All
The Vermont Health Department supplied NIOSH with the readable radiographs for 8 of the 11 men who died of malignant respiratory disease Of these eight with readable radiographs six 75 had radiographic readings of 2/1 or greater indicating pneumoconiosis All of these were small rounded opacities the type usually observed with a fibrous exposure and were generally distributed throughout the lungs Two of the 11 ONMRD had prior dust exposure When these two were excluded six readable radiographs remain Of these 83.3 5 were read
as 2/1 or greater Note should be made that these radiographs were taken while the workers were relatively healthy that is healthy enough to be actively employed
Furthermore this information was supplemented by qualitative radiograph readings recorded by the Vermont Health Department for each annual survey No discrepancies were found when these were compared to the readings discussed above The Health Department information included readings for the three deaths whom radiographs were either missing or unreadable For the two cases with unreadable radiograph earlier readings were available All three cases had radiographic evidence of pneumoconiosis according to the Health Department's physician at the time the radiograph was taken With this information incorporated into the tally a total of nine of the eleven had radiographic readings consistent with pneumoconiosis
ASSESSMENT OF OCCUPATIONAL EXPOSURES
Analyses of both airborne dust samples and talc bulk samples showed talcs from all locations in the mines and mills studied to be similar in composition No asbestos was detected in any of the samples analyzed by either ray diffraction or analytical electron microscopy Levels of free silica in talc bulk samples were below 0.25 for nearly all samples and only in occasional air samples was free silica detectable Talc shards and ribbons were seen in talc bulk and airborne dust samples In addition to the mineral talc other minerals present in these ores in significant quantities include magnesite chlorite and dolomite in addition to traces of calcite biotite ankerite and phlogopite
To determine potential differences in the talcs mines and milled by the company
in the third geographic location no longeirnoperation seven samples of talcs were
obtained and analyzed by the same techniques mentioned above These samples were found to be free of asbestos contamination and to have a mineral composition within the range of samples from currently producing operations The one remaining company also no longer in operation was located in the same geographic area as two of the currently operating companies
The historic data on the studied facilities obtained from the Vermont Health Department were not sufficient to calculate cumulative exposure histories for miners and millers However they are sufficient to demonstrate that it was not uncommon for past exposure levels to both miners and millers to far exceed the present Occupational Safety and Health Administration OSHA and the Mining
Cincinnati ratings were not used
Analyses presented in Boundy M Occupational Exposures to Asbestiform Talc in Vermont Presented at Conference on Occupational Exposures to Fibrous and Particulate Dust and Their Extension into the Environment December 6 1977 Washington D.C.
Enforcement and Safety administration MESA standard of 20 mppcf for nonfibrous
talc % free Sio NIOSH 1974
"
The talc in one of the closed mines is reported to have had cobblestones of
serpentine rock which were highly tremolitic In the mining of this talc these cob-
blestones were avoided and discarded Therefore miners may have been
exposed to tremolite but it is unlikely that the millers from this company were Radon daughter levels in Vermont talc mines have been determined by MESA
Mean levels ranged from trace quantities to 0.12 working levels Single measure-
ments as high as 1.0 working levels have been measured in these mines
NIOSH is currently attempting to identify any possibly confounding workplace
Vermont exposures that may have occurred prior to or after employment in the
talc
industry for those who died from malignant or malignant respiratory disease
Prior exposures have been identified to some extent by Vermont Health Department
Records
DISCUSSION
workers The finding of excessive respiratory disease deaths among talc
re-
quires an evaluation of selection bias resulting from application of the criteria for
inclusion in the study population Bias may exist from selection into employment in
this industry and subsequent radiographic examination as talc workers During the
annually early years of the program radiographic examination was not done
There
was no survey of talc workers for six of the first twelve years During this time the
likelihood of missing workers with brief exposure was greater especially in the
period from 1944 through 1947 when no examinations were done The bias associated with radiographic examination appears small as the probability of examina-
tion increased with increasing length of employment As the data were examined by
analyses latency and exposure categories this bias was accounted for in the
The
Health Department in the mid 1960's did attempt to document those missing in their
surveys Although the completeness of this documentation is unknown the follow-
ing information resulted Of the 178 workers identified during this check approximately 27 worked more than one year but less than % worked more than five
years This supports the theory that those missed by the surveys were for the most
part short term workers
To examine the effect of potential selection bias for persons with a predisposi-
tion toward respiratory disease analyses of ONMRD mortality risk were made
according to latency that is the time interval since onset of initial employment in the
Vermont talc operations The mortality patterns in millers demonstrate an observ-
able excess after 15 years of employment 2 observed versus 0.31 expected
a observed 0.05 and statistically significant risk after 30 years 5
versus 0.41
to expected 0.01 This lack of an excess prior 15 years and an increasing excess
beginning after 15 years suggests that there was no selection bias toward less
healthy workers the data were consistent with other data comparing working
populations with the general population This phenomenon is known as the healthy worker effect Bayliss et al 1976 McMichael et al 1975 Those who are
employed have lower death rates are generally more healthy than the general
worker population which includes invalid and institutionalized people This healthy
effect is more prominent in the years immediately after the workers are hired
Waxweiler 1976
:
practice
it
unlikely
Since employment health screeningscrening was not past practice is unlikely that
thus job selective
selective such
placement
mine
mine
versus
mill
occurred
due
to
health
status
and
not explain the different trends observed
selection could The role of prior employment in other dusty industries can be reasonablyreasonably
excluded reasonaiblny to in the etiology of this malignant respiratory disease death risk
two
who died from ONMRD had reported dust exposure prior working
workers two cases are excluded from analyses the pattern of an
exces ive industry excessive riskWhofenONMRDONMRD mortality in millers persistspersists 7 observed versus 0.89
expected 0.01
significant
If there is truly an association of the statisticallystaistcaly significant excess of ONMRD
would examina- deaths with talc exposure one
expect a confirmation of this with an
dust exposures paper Insufficient historic data are available to estimate cumulative life for members of this cohort however available data show past
sinurtehse mines and mills to be higher than the present OSHA and MESA exposure
standard of 20 mppcf It is probable that cumulative dust exposures for millers over
their
time are higher than those of miners as mine operations are more :
workingin nature than are mill operations eg intermittent operations such as
sporadicAlthough there may be other possible factors the relative differences noted
drilling in
expected malignant respiratory disease deaths in the
observed versus
+
consistent with a talc exposure etiology At this
and milling populations are
mining scientific the mines are extremely limited too limited to make respiratory
judgement datajudgement as
theto the
presencepresence
or
absenceabsence
of
an
excess
malmailiggnantnant
respiratory
a '
disease death risk
A majority of those workers who died of malignant respiratory disease or
respiratory cancer did smoke cigarettes at some time during their lives Unfortu-
nately no data the smoking habits of the study population and precise data
the
populations are available However it seems unlikely due to the -
comparisonof the difference that the observed excess of malignant respiratory
magnitude millers limited disease deaths is associated only with unusual smoking patterns and then only
talc
It is equally unlikely that the excess risk of lung cancer found in
among
the
is associated with unusual smoking patterns only in that group Because
miners
of
smoking data no conclusions may be drawn from these mortality data
the possible additive or synergistic effects of smoking and talc dust
conceexpronsuirneg
SUMMARY AND CONCLUSIONS
present The
study demonstrated excessive mortality due to malignant
a asbestiform disease among talc millers exposed to talc free both of
respiratory
of free silica Selective bias and other causative
minerals and significant quantities
factors do not adequately explain the observed excesses although the possibility
does
exist
of
an
interactive
effect
between
cigarette
smoking
and
talc
exposure and
Radiographic
evidence further support the role of talc exposure free of asbestos
Radiographic free silica in the etiology of the increased risk of malignant respiratory disease
among these talc millers
past levels associated with this excess is unknown
The cumulative talc exposure
of the mills and mines However the
nature of early sampling
not uncommon for past
due to the sporadic samples are sufficient to demonstrate that it was
Health Administ-
levels to far exceed the present Occupational Safety and
exposure
and Safety Administration standard of 20 mppcf
ration and the Mining Enforcement
for fibrous talc % free Sio reflective of these early exposure levels No
Mortality patterns observed are
the effects of present day
can be made from this study concerning
judgement
exposures in this industry
was observed for miners and not
The fact that excess lung cancer mortality
that
millers despite probable higher daulsotneexoproisnucroemsbiinnatmiilolnowpietrhattailocndsusstuagfgfeecsttmine
additional etiologic agent either
for this cancer mortality risk
workers The possible role of radon daughter exposures
cannot be eliminated
ACKNOWLEDGMENTS
studies for this report were conducted by Maryanne
under The industrial hygiene Harvard University School of Public Health
the
Boundy and Karen Gold of the
and
microscopic
petrographic direction
of
William
A.
Burgess
ray
diffraction Walter
C.
McCrone
Associates
studies of talc bulk samples were conducted by
under NIOSH contract
Felson M.D. of the Department of Radiol-
Radiographs were read by Benjamin
ogy Cincinnati General Hospital and the United Cement Lime and Gypsum
The authors thank Don Spatz
studied and the Mine Enforcement
Workers International Union the companies
and Safety Administration MESA for their assistance
Clorinda Battaglia
The authors also thank Debra McDonald Patricia Johnson
and
and
the
mortality
group
Mary
Gabriel
Edith
Dodd
and
the
follow
group also Lina
Heid of the National Institute for Occupational Safety and Health and
Marian
Health Vermont Health Department
Bizzozero of the Division of Occupational
Ohio Regional Computer Center
Bruce Gehring Mary Quinn and the Southwestern
Staff Cincinnati Ohio
REFERENCES
H. .. Mortality patterns among fibrous glass
Bayliss D. L. Dement J. M. WagYoonrekrAcJ.adK.emayndofBlSecjieernces 271 324-335 1976
J. of Occup
production workers Ann New
and environmental carcinogen
.: Talc a possible occupational
Blejer H. P. and Arlon
Med 92-97 1973
to talc in two Georgia talc mills Public Health
Dreesen W. C. and Della Valle J. M Effects of exposure
Service Reports 131-143 1935
388
SELEVAN AL
Fine L. J. Peters J. M. Burgess W. A. and Diberdinis L. .: Studies of respiratory mortality in rubber workers Part IV Respiratory morbidity in talc workers Archives of Environmental Health July195-200 1976
Kleinfeld M. Messite J. Kooyman O. and Zaki M. H Mortality among talc miners and millers in New York State Archives of Environmental Health 663-667 May 1967
Kleinfeld M. Messite J. and Tabershaw I. R Talc Pneumoconiosis Archives of Industrial Health
66-72 July 1955
Kleinfeld M. Messite J. and Zaki M. H Mortality experience among talc workers A follow study J. of Occup Med 345-349 May 1974
Maranzana G. C. and Tronzano L. T Epidemiology of silicosis in talc mines Medicina del Lavoro
591-596 1963
McMichael A. J. Haynes S. G. and Tyroler H. A Special Communications Observations on the evaluation of occupational mortality data J. Occup Med 128-131 1975
Millman N Pneumoconiosis due to talc in the cosmetic industry J. of Occup Med 391-394 1947 Pearson E. S. Hartley H. O. Editors Biometrica Tables for Statisticians Volume , 1958
'
Porro F. W. Patton J. R. and Hobbs A. A Pneumoconiosis in the talc industry Am J. of Roentgenology and Radium Therapy 507-524 1942
Rubino G. F. Scansetti G. Piolatto G. and Romano C. A Mortality study of talc miners and millers J. of Occup Med 18 No. 186-193 1976
Scansetti P. G. and Rasetti L On pneumoconiosis of talc workers Medicina del Lavoro 680682 1963a
Scansetti P. G. Rasetti L. and Ghemi L Clinical and radiological course of penumoconiosis in the talc extraction industry Medicina del Lavoro 746-749 1963b
Seeler A. O. Gryboski J. S. and MacHahon H. E Talc pneumoconiosis A.M.A. Archives of Environmental Health 392-402 1959
Siegal W. Smith A. R. and Greenburg L Study of talc miners and millers in St. Lawrence County New = ; York State Ind Bull 22 December 1943
Thorel C Die Specksteinlunge Ein beitrag zur pathologischen anatomie der staublungen Beitr Path
Anat 85-101 1896
U. S. Dept. of Heath Education and Welfare National Institute for Occupational Safety and Health Criteria for a Recommended Standard Occupational Exposure to Crystalline Silica HEW Publication
.
No. NIOSH 75-120 1974
-
U. S. Dept. of Interior Bureau of Mines Minerals in the U.S. Economy Year Demand Profiles for Mineral and Fuel Commodities 1965-74 1975
Waxweiler R Quantification of risk from industrial carcinogens Presented at the Detection and Prevention of Cancer Conference New York City April 1976
AN ANIM
J.C. Wa
Medical
pital
pital Pe
F.D. Po Po
Dept.
INTRODU
In this pape
given
are given In a
nary results of
cosmetic talc us
those of chrysot
MATERIAI
The main
a shipment of t been produced reasons Firstly secondly beca
obtained from
This partic imported in a median particle mineral by weig
also found in th Extensive
year perio
were over 30 y
no change in th
asbestos mine the many sar itself has show could not be tra
procedures ad
For compa which we have
inoculation W exposed to nei