Document jBLR0pnzzNpz4wkkZz6ZGnng5

ii* > . It \ - ' * * *' * / i ? sm .-*.your present Committee. No speoifio "scientific evidence" has so far been pre- - seated for our consideration along with this criticism. * , -* Aij/, ,. % " While it will doubtless be very advantageous to hare what might be called J permanent or standard maripum allowable oonomtratioa values* It must be borne in 1 mind that all our'values at the present time are fluid and subjoot to annual roi via ion* They should not be adopted as fl*cd or legal values* but merely as guides to'assist ua in defining more or leas safe working eonditiona* It is felt that ] eventually definite values oan be .established whioh will give full'and ample pro- . teotion to tho worker. . - .. l{ . ' 'The following changes have been mo.de ,ln the values from those of the 1947 conference: * Benzene has been dfcreased from 9 *9; ,<55f ppia **? Chlorine bias 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 cyanide 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 ... '. 2-Butanon.e ho^*peen increased from-200 tp 250 pga '. Isbpropyl' ether 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* fron 0.1.mg./cu.m 'to.Q.5 Sulfuric acid has been increased from 0.5 mg./cu'.m. to 1.0 It must be borne in mind that these values ere 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. * ' . '; ,, onse to drugs end toxic substances. 7v With 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 ekpect that we can have occasional cases of ^poisoning. 9. * ' l*' < 'THRESHOLD LIMIT . VAUJIS ADOPTED AT APRIL. 1948, MEETING OF AMERICAN ' j * GCNFER|NCE OF GOVEHNUENIAL. INED STRIAL HYGIENISTS IN BOSTON, MASSACHUSETTS -'.Esrh^.'l. -n: cio. - tf.. y > .v-f-E^r* ' v-. ?v; SUBSTANCE Acetaldehyde *: r--r .^'Acetic acid r*'-" .,'4^ Acetio anhydride k .Acetone GASES AND VAPORS P.P.U. v.wr*:r-w.SUBSTANCE 200 ' Acrolein - vaotc:e- -.; J 10 Acrylonitrile 6 ' Ammonia *' 500 Amyl acetate -Vv P.P.M., vy;; 0.5 20 " 00. V '*' 200