Document 8276Q4mX9Z9eYvJvYdL8m9Q5K

FILE NAME: Owens Illinois Library (OWL) DATE: 1956 DOC#: OWL050 DOCUMENT DESCRIPTION: Conference Presentation - Symposium on Threshold Limits * T - ` `W v -- * r> % n S 2 7 3 9& ) ' i 9 ( l i Thi* material has bean reproduced with pi .mission of the copyright owner. Further reproduction is prohibited. Symposium on Threshold Limits Present Trends in M ACs Introduction by WARREN A. COGK. Associato Professor Industriai Health and Hygiene. Scltool of Public Health University of Michigan. Ann Arbor Tkc THINKING today on the concept of limit* and the improper use of them. N o threshold limits of injurious materials, where is the present concept of threshold ! designated by whatever term, has passed limits more ably and competently expressed through an evolution to a gratifying uta than in the papers and discussions of this turity. Symposium. Initially the need to know how little of a That the discussants might not have the toxic substance might remain in an indus very last word, it may be permissible for trial atmosphere without injury to those ex this prologue to assume in part the preroga posed was insistently apparent. Such in tive of an epilogue! The following com formation began to be supplied through cor mentaries appear pertinent. relation of concentrations of injurious sub The last publication of the American stances with observed effect on the health Standards Association Z-37 Committee on of the worker for such materials as granite Maximum Acceptable Concentrations of dust1and lead compounds.* Results of short- Toxic Ousts and Gases* is reported cor time animal experiments had been available rectly as 1949 by Sachs who deplored the even before the present century from such lack of revision of the 1941 Standard for I investigators as- K. B. Lehmann* and later benxene at the obsolete level of 100 parts from Yant and others a t the U. S. Bureau per million. It is to be noted th at this ASA of Mines,4 with the classic combined long- Committee is now active in the revision and_ exposure animal experimentation and oc publication of MAC Standards for many* cupational study on bensene by Greenburg* of the materials on which information U in the middle twenties. available. As these threshold limit values became The term "maximum acceptable concen more numerous and were more widely ap trations" was adopted by the ASA Commit plied, It is perhaps not surprising th a t mis tee for a number of reasons. The word "ac conceptions and aberrant usages occurred. ceptable" does not connote the legal control Some persons erred in considering the levels inherent in the words "allowable" and "lim more precise than the facta justified; others it," but rather a simple acceptability with rejected them because the values could not out further implication. Also, the expres precisely fit all conditions of exposure and sion, MAC, htx been widely used over the physiological response. And the detractors years aud is now a part of the language. In were for a while more vociferous and seemed fact the Germans adopted a wording which possibly to be more sound than the pro gives the abbreviation, MAK, so that this S tagonists. term may be used in international conversa With time, there has been a separation of tion. Their words as used in the title of a the valuable advantages of the threshold paper by OetteP are "Maximale Arbgts- F r m i u d u |h t M a t I m l w t f U , An m c a n I n- H tn u L H iu in i Au o t u t m H~ A m(U C 'N C m n w in w (iovuN H iN U i In m it iu l Hvifriu ra At ti n ISM la SiutriAl S n U ( M n u n , S t M a ApiU St. IMS. platz-Konxentration." It is understood that this same expression is being used in the "MAK" tables of the German Association for Worker Protection. S74 StfU m ktr, M St However, there cm be no really valid ob jection to the term "Threehold Limita" need by the committee of the American Confer* ence of Governmental Induatrial Hygieniate or to "Hygienic Guides," the term adopted by the American Industrial Hygiene Asso ciation committee. This Symposium would not be complete without reference to the availability of the excellent AIHA Hygienic Guides to which reference is made else* where in this Journal. One of the most perplexing problems in arriving at threshold limits is posed by the rancerigena. Stokinger's statement in this Symposium is the first publication on this phase of the subject. However, the use of the procedure suggested by Stokinger as ap plied to nickei carbonyl has already drawn some fire. Quoting in pait from a private communication from Oettel whose publica tions1-* on "MAK's" include a well-consid ered presentation of the general subject: "We suggest that consideration be given to indicating the suspected cancerigens with an asterisk with reference to a footnote that the hasard exista M d consequently especial ly effective control measures be instituted. No man can aay today which concentration of the aeveral induatrial substances is actu ally required to be cancerigenie . . This statement follows bis objection to the pres ent listing by the AGIH of nickel csrbonyl as 0.001 ppm on the basis of its al leged CMcerigenidty, which incidentally Oettel'a extensive experience with the sub stance causes him to doubt, while failing to include any acknowledgement of the known eancerigeniclty of arsenic, chromates M d asbestos. Says Oettel "In this I see a great danger. The lista should in any event remain logical." Waters* discussion of Brandt's paper oc cupies the final pages of this publication of the Symposium, but it Is believed that W aters would not wish his comments to be considered the last word on the subject of threshold limits--rather that his observa tions are limited essentially to the use of theue values in legal codes, rigidly fixed by statute. As the last word in this Symposium, this introductory refers the reader to the concluding paragraphs of the paper by Brandt for his discussion of the philosophy of threshold limits. References I. I l'M U . A. X. SiTTiN, a. M., T ssarw u. L L , UtooaruiM. J. J.i Tfc* HnMJi al Wsrkrra to Owl Tiwto II- Eivwuf* U SlUcww Owl (Ciw Hi M w l q l . t a Mr Mtaltk Bmll. tu . 1ST, I. X I u m u , A. E.. J u - X X . SiM nnua. I . I , h i m * . E. H - Tatar*. L. a.: L a i M m Ii i to StoiM* t o t u i , r iu L h t o * Mrallk MM Mm ttl. IMS. X Ia iu u sji. K. a.; Mamraaa m i n i towiv *k- IS M to I r r t i i far Matumt Irma Ibt IMS'. 4. ta t it . W. r . u 4 N l l a i W ! Acato S h w at Gala V* to Vm m a l Su m Mm CaauaMctol Or* u k Cm p m i A . A w r tn a t a * rm *hlk4 to fabil* H n U S o t o S tria e lb* ISM'*. 5. Cu u m i c . L.: I n a l N w Ih u m l i t o trial I b u i i M b alto S r |N , 41. ISS1, 1414, u 4 isis. ms. X Atoirl u a Si i U i i A Auattolto*: l i u l t t o aa At. aaeuMt CaataalnltoM al T atIt Dwlt aa4 C tttt. ASA. M X 4ktb B littt, N t Vark It. Mt Varfc. I. O n m . U-: Ola aaaimalt ArtoiuakU-ICaawaUa. Itoa I s MAK-Wantl atkaSktktt Gaat. Oaa>it amt SUato. S it Or>a/a**aaaraarta/t. Na. X Vakraar*. n i l . X O n t o . K.: CmarkUtka Vareillaaata Sank Gaaa. Dttoala M l S u r k ts ta . Arrkit tar ra d la k fii. 11:41, USA The Need for Threshold Limits MIRIAM SACHS. M.O. New Jersey Steio Department of Heelth, Bureau of Adult end Occupational Health Trenton. New Jersey PlOBABLY one of the most basic needs in human endeavor Is for man to have an orderliness set to his mMner of thinking. Everyone has a need for discipline, for. boundaries to be drawn, and for limits to be' defined. U does not m atter that the only use for some of the limits so defined may be to ignore them; they have still served their purpose as a point of aim for individual interpretation. If this seems eryptic, an ex ample concerning a common substance may be cited. Almost everyone la familiar with the threshold limit values for .silica--for dust with a free silicon dioxide content above 60%, the limit is given as five million parti-