Document xjN3ynjG1wbRVmDr0XR4gRZx6
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. REPORT OP THE C02UTTEE ON THRESHOLD LIMITS
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DR f* PAIREJMX,- (U. S. Publio Health Service) i It 1* obviously difficult,
where a large number of substances is involved# to review the
allowable *
concentration values in detail at an annual meeting. Fbr that reason, provision
,\wae made early in the organisation of the American Conferenoe-of Governmental In-
/^dustrial Hygienists for a Committee on Threshold Limits to study this question and
to report to the'Conference at its annual meeting. The composition of this Com
mittee is not fixed but is changed by annual appointment and the threshold limit
^'values are similarly maintained in a fluid stato by annual revision. For a number
'of years the Coamittee has subjected these values to oereful scrutiny and attespted
to bring them into close conformance with practice.
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During the present year, it was folt that the ooncept of maximum allowable
values had now reached a stage where more, extensive participation of the members
of the Conference in the formulation of these values based upon personal experience
in the field would be of deoided assistance. This year# therefore, your Committee hes for the first time, I believe, made a direct attempt to obtain a statement from each member of the Conference with reference to tho annuel threshold limit
values end the resoonse from the lndividir.1 nembers has been most generous and
helpful.
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/ In view of the* annual revision of threshold limit velues,it has been the pur pose of the Conference to seek values which, on the one hand protect the individ
ual workman, and on the other would imposo no impossible burden on the manufac
turer, This balance Is difficult to achieve but can be attained by just such a
series of adjustments as is provided for in the Constitution of the Conference,
fi There is no industrial poison so potent, so virulent, that it cannot be manufactured safely under carefully controlled conditions. The manufacture end widc-
' spread use of such a substance as lead tetraethyl and tho preparation of extremely
poisonous war gases are good illustrations of this. In fact, the chemical manu
facturing Industry in general has been able to maintain a high standard of safe * industrial practice by the installation of suitable control measures for the pro
tection of its workers. There is no reason why 6uch safe industrial control
measures cannot bo extended to industry in gcnernl wherever industrial poisons
occur.
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In addition to the cbnsnonts of the members of the Conference, a few criti
cisms from other sources have reached us, concerning tho 1947 values. These may
be briefly summarized as follows:
'' * 1. Concerning the membership at large, criticism has taken the form that
(a) vnlucs were arrived at by consulting tho membership at large, and (b) thet
the members were not consulted.
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2. The publication of the values in the Industrial Hygiene newsletter made
./> it appear thet the values were those of the U. S. Public Health Servioo. -whether
' 'this was wishful thinking or not,, the source of tho 1947 values was dearly in-
diceted at tho time of publication. ---------- :
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' 3.*' Criticism has cIso taken .the form that tho values given wero not arrived
-<^J'ot .or based upon scientific evidence. The latter hes particularly interested
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sm .~*.your present Committee. No speoiflo "scientific evidence" has so far been pre-
sented for our consideration along with this criticism.
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>.' " ' ' While it will doubtless be very advantageous to have what might be called
J permanent or standard maxtpum allowable oonomtration values, it must be borne in
1 mind that all our'values at the present time are fluid and subjcot to annual ro-
i vision* They should not be adopted as flxcdorlegal values, but merely as guides
* to'assist us in defining more or less safe working conditions* It is felt that '
] eventually definite values oan be .established whioh will give full'and ample pro
. teotion to tho worker.
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'The following changes have been ma.de,in the values from those of the 194? *
conference:
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Benzene has been decreased from 9 to $5, ppm . 7/ . .. .
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Chlorine hae been decreased from 2.to 1 ppm ' ' Formaldehyde has been decrecsed from 10 to 5 ppm
Hydrogen chloride has been .decreased from 10 to 5. ppm , _
Hydrogen cyrnide hrs been decreased from 20 to 10 ppm
Hydrogen selenide-has been decreased from 0.10 to 0.05 ppm
Trichloroethylene hes been decreased from 150 to 100 ppm
Iodine has .been changed from .1 mg./cu.m, to 1 ppm
'; B^Butiinoa# hof-rpeem Increased from-200 t? 250 pga
Isbpropylether has been increased.from 400 to 500 ppm-
Antimony has been increased from 0.1 mg./cu.m.",to 0.5 .
Arsenio has been increased'from 0.1 mg./cu.m to.Q.5
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Sulfuric acid has been increased from 0.5 mg./cu.m. to 1.0
It must be borne in mind that these values are not'indices of toxicity and
are not intended to approach that value. Accordingly, the comparative toxicity
of these compounds cannot be established on the basis of their numerical maximum
allowable concentration value.
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onse to drugs end toxic substances.
7With these facts in mind tho Committee has set values below which it is fair
to expect reasonable protection and above which it is reasonable to expect that m
we can have occasional cases of poisoning.
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' v*' <- ' THRESHOLD LIU IT . VAUJ IS ADOPTED AT APRIL, 1948, MEETING OF AMERICAN '"I--. *' GCNfEHPICE OF GOVEfihMEH?ALc INDUSTRIAL HYGIENISTS IN BOSTON, MASSACHUSETTS
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GASES AND VAPORS .. 1,-
%
V
e&VvH*** ' v--
f r.
V >
SSUIIRBRSTTANCE
. .* Aoetaldchyde
: Aoetio acid ~J *
.i\Acetio anhydride
i 11- --
"
P.P.U.
-::<1 ;:
200 10 6
-- .--.
. * r*. ^, ' _ iwi.WBSrillOE
Acrolein
^
Acrylonitrile
Ammonia '* .v.3:>
.. * " ..i y : ~~ p.pji-..
0.5
;
Z~'' 20 . V: 100
" 0.
i1:.- Acetone . .
500 Amyl acetate
. 200
./
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.-A .
GASES AND VAPORS (cont'd.)
' r.SUBSTANCE
. P.F.M.
. - SUBSTANCE
P.P.M.
...Iso-Amyl aloohol
..."Aniline ..
*: ^Arsine ' '
/Benzene (bmtol)
'/Bromine
;;;i,3-Butadiene
' "'tt-Butanol
2-Butanone
. ,.
. n-Butyl acetate
..
Butyl oellosolve
.
Carbon dioxide
' Carbon disulfide
* Carbon- monoxide
100 5 0.05
35
1
:i,ooo
50
--___250 200
200
5,000 20
r" .* 100
Ethyl formato
Ethyl silicate
Forma ldehyde
Gasolene . Heptane ..
,A
Hexane
'
Hydrogen chloride
Hydrogen cyanide
*
Hydrogen fluoride
Hydrbgen aelenide
Hydfogen sulfide .
Iodine
Xsophorone
100
100
.5 500
: 500 : 500
5 10 - . 03- . OS - " 20
1 25
'Carbon tetrachloride
'IV 50 Mesityl oxide - '
50
Cellosolve
t - 200
Methanol
200
Cellosolve acetate -
100 Methyl acetate
200
Chlorine
"
/ 1 Methyl bromide
-
20
2-Chlorobutadiene
25
Mothy1 butanone
100
Chloroform
100
Methyl cellosolve
25..
1-Chloro-l-nitropropan e
Vm*" 20
Methyl oellosolve aootate
- ; 25'
Cyclohexane
400 Methyl chloride
* 100
Cyclohexanol
.-< ~ 100
Methylcyolohexane
500
Cyclohexanone .
-*'** 100 Methyl cyclohexanol
100
Cyolohexene
*' :
-400
Methylcyclohexanone
. 100
Cyclopropane (propene)
400 Methyl formate
100
o-Dich lorobenx ene
50 * Methyl iso-butyl ketone
100
Dichlor odifluor one thane
1,000 .Monochlorobenzene
75
1.1-Dichloroethane
-
100 Monofluorotrichloromethane
1,000
1.2-Dichloroethane (ethylene
Mononitrotoluene
5
dichloride)
1.2-Dichloroethylene
v
Dichloroethyl ether ; **
Dichloromethane
' *
Dichloromonofluoromethane
' 1,1-Dichloro-l-nitroethane
75 . Naphtha (coal tar)
' 200 - Naphtha (petroleum)
* 15 Nickel carbonyl
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' 600
Nitrobenzoie ' *- *;
1,000
Nitroethone
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10 . Nitrogen oxides (other than N2O)
200 500
1 1 100 25
1.2-Dichloropropano
' Nitroglycer in
. 0.:
(propylme dichloride) * 75
Nitromethane
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.. 100
Dichlorotetrafluoroethane
1,000
2-Nitropropane
50
Dimethyl aniline
5 Octane
500
Dlmethylsulfate
. l Ozone
1
Dioxane
. 100
Pentcno
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1,000
Ethyl acetate
400 Pen tan one (methyl propenone)
200
iv Ethyl alcohol Ethyl benzene
r'thyl bromide
Ethyl chloride
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`1,000
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200
' 200
1,000
Fhosgene .o: is fv.t-.-r..
Phosphine
.
Phosphorus trichloride . .
Iso-Propanol
1 0.06
0.5
400
Ethylene chlorohydrin
6
Ethylene oxide
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100
Ethyl ether per ,..r * r~ . . i ' 400
Propyl acetate
Iso-Propyl ether
Stiblne :
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2*>=ep.tiv.
200 500
0.1
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^ CASES AND VAPORS (cant'd.)
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SUBSTANCE
a . ... P.P.U,
. : SUBSTANCE
. ** .
3 At
',r Stoddard solvent Styrene monomer Sulfur chloride Sulfur dioxide
, 500 Toluene ', ;
- - -v ;..uvhr2.?^ -Toluldine
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.Trichloroethylene
4S-:?-C
* > Turpentine
..
?> !.*vf W i tt *
ll#2#2-Tetr*chloroethane
6 " . Vinyl chloride
Tetraehloroethylene
. m * loo
.V
-P.P.P.
r .200
-s ''.100
100 :S00
200 ->
. * . ;
3
%*'
` - . -S-
/ l A' *'* 1 -
1 ***.** -'.I*. ` llg. per
' * SUBSTANCE
; .. m cu. m.
.
' 1' f s ' * ' Mg. per SUBSTANCE *. . . cu* m.
yr
Antimony
0.5 . Mercury
; ..
Arsenic
0.5 ' Pentachloronaphthalene
Barium
- 0.5
Pentachlorophenol ;
Cadmium
.
0.1
Phosphorus (yellow)
Chlorodipheny1
l
Phosphorus pentachloride
Chromic acid and chromates as Cra.0.1
Phosphorus pentasulfide
Cyanide as CNN
. . .5
Selenium, as Se
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Dinitrotolucno
1.5 Sulfuric aoid
Fluoride
2.5 Tellurium
Iron oxide fume
* 15 fetryl
Lead
' ; -.* 0.15 Trichloronaphthalene
Magnesium oxide fume
15
Trinitrotoluene
Manganese
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. 6 Zinc oxide fume
.0*1 . . 0.5
. 0.5 0.1
.. 1 i 0.1 1.0
. o.i 1.5 5
1.5 15
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* .. SUBSTANCE '
* MINERAL BUSTS * V
M.P.P.C. F.
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' * SOBSTANCE * -vM.P.P.C.F.
Alundun
. ' ' -60
Silica:
-
-Asbestos
#
. .5. ,> high (above 50# free SiO)
Carborundum
* ' 50
medium (5 to 50# free SiOjg)
Oust (nuisance, no free silica) 50
low (below 5# free Si02)
Mica (below 5# free silica)
50 Slato (below 5# free Si02)
Portland cenent
Talc
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: 50 ' ' 20
Soapstone (below 5# free SlOo) Total dust (below 6# free Si^)
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RADIATIONS
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5 20 50 50
20 50
MATERIAL OR RaDIAIION
Radiant t faergy
Radiant MATERIAL OR RADIATION Energy
Cessna (roentgen per
. . 0.1
Radon (curies per cubic meter) ' ia"8
ft *
fhoron (curies per cubic meter) 10"
X-ray (roentgen per day) " . > 0.1
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