Document 4J4VXLZeLmre2vgY8JVzvXy2x

42 Tuvuty-seeond Congress--National Safety Council injurious and are. therefore, removed from the sample. After proper dilation, the cincuts of the irradaated ffok are thoroughly shaken so that a uniform suspension is faatncd. and two portions about one cubic centimeter are removed with a l>il>c1te to just 6U two Scdgurkk-Itaftcr counting celts. The cells are allowed to Asxnt at least 2N mimnes and the dnst pankies are then counted by mans of a mkro*-opc. The imctwctpe with an AMe oetden^er is provided with an eyepiece micrometer, a lG-roOlimctcT objective and a /JC eyepiece. The eyepiece micrometer has a lane square engraved va it. and this sqtarc is divided into 100 squares, one ot which is forther divided into 25 smaller squares. The proper tuhr length of the microscope b determined by calibration with a stage micrometer, so that a side oi the large square of the cyqw.T covers I millimeter (1.000 microaj). The large span d the eyepiece micrometer, therefore, encloses the dust in an area oi rate s*|tare millimeter. and since the counting cell is one millimeter deep, nil the du>i suspended m one cuhk miltimcte*- of the sample b under the ruled field All particles visually b> than 10 microns in longest diameter m one quarter of the field are counted at fin |>outts cm the cell, namriy. near the fmr comers and the center. Two cells i each dnst sample are counted and the average of 10 counts b obtained. Control count# are subtracted from the average sample counts, glvfog finally, average net eoemts the mxndwr of particles which are then calculated m terms of particles per cuhtc frail of air sampled. Having determined the owwlraiin of dost particles less than 10 microns in diam eter in a given atmosphere, it is jlm necessary to rditaki information regarding the mineral composition of the dust before any cvaltalion of the health hazard can he made. In general it may k said that the harmta!oess of a quartz containing dust b usually in direct proportion to hs free-silica (SK>>) content. It is. therefore, uecessanr to distinguish between "tree silica-, that is the silica that occurs as quartz, and "cranbmcd silica-. or the silica that b combined with other dements in the various silicate minerals. It should he borne m mind, therefore, that the total silica reported in the custraiory chemical analysis is no measure of tk amount of free silica. The quartz content of fine dusts is usually determined by a wwnVimtwn of petrographic and chemical methods. Each dust presents individual problems and no individual technique applies to all dusts regardless of their composition. Those interested in this imMem should consult Reprint Xu. 1560 of the Public Health Re ports. February 24. I9S.V entitled The Quantitative Determination of Quartz (free silka1 in Dusts- In* A<k4|4t Knopf. Professor of Physical Geolr^y. Yak University, and Goniltant. United States Public Health Service. /JY'1' Discussion of Dust Problems By DRl LEONARD GREBNBURG . Tale University. New Haven. Ccmn. The speaker takl m jam: On the ledmical side of this problem vnu have been presented with two cxreOcnt tapers liy Mr. Junes and Dr. Meitcr. There is little that I sit*mid atkl from this poira d view. Perhaps the mnt valuable contribution that I can make is to prescat to you my own personal vtcvr oi the Iiroodrr adminis trative aspects if this problem gained as a result of many yean of close contact. In order to do this, let us analyze the problem in its simplest terms. Dust Problem iu Industry 43 We may begin l*y agreeing that pulnsstary fikwii result* ireu the inhablto d certain Hosts in known cmceotraltiwi m-r a sufficient |*cr**l of lime. This fact has been dnmntratnl repeatedly by means i industrial. hlwl*iry and luthuttgical studies. On tkb simple fact. I take it. there is complete agrcentenL Such kgitimatc cases of disabling pulmonary ftltmsi* are held in many states ti lie the responsibility of the employer. Further, a perusal of the compensation laws makes it evident that there exists a ktled trend in the direction if broadening the compensation acts throughout the Union fur we find frum time t time that additional states are being added to the list of those holding silicosis to k a ant* pcnsable disease. We would certainly be Winding ourselves to the facts were we not to admit the existence of this trend in seal legislatuav. It should he pmttal out here that this is a very whWr*vnc and desirable state oi affairs. The insurance principle has justified hs existence in spreading the tmrden of ill fortune over a Umg pcried of freedom from eatastrojihc and surely- in the case ot industrial accidents h has freed us from the deplorable state of affairs in existence prior to 1912. In the case of the ncctqatimal diseases we may Itupe for opally satisfactory result*. Nevertheless, compensation insurance is i*4 the complete snlutuei *>i thv pmhkxu at hand. The only ailajute means of auwfinR the lunkn <it silicosis is by the |mvnticn of this disease. All other mrlhtxls du mg loach the crux of the problem ami they carry m their wake a vast amount of litigation, illness, and a large fuancial burden on industry. If what we have agreed tqxui to ibis point L* true it is obvinus tint industry most prevent tlte ritsscrranaltrai uf dust hi the wurkrtituu air k sorb adequate engineering technique* as are availalilc: *ir in certain cases where this is not possible industry must provide, and fnre ilw worker ( use. such means of licrsunal protection as will adequately safeguard him against the inhalathai <if dust. It t* only by these means that wc can guarantee a future free of disabling polmraiary discasc <!ne to dust inhalation. In sphe of the very best efforts f industry In solve this |*rt44cni iIktc trill undonlitcdly be a certain number uf cases brought to the courts'and iwcscntcd as legitimate cases of silicosis. \VhUe some of these are true cases rd silicosis others. I have been informed, arc not. but are designed merely as a means of ofdarning funds from industry. A consideration of such cases brings ns logically to the scomd Iart of the iwescat discussum. What is the ideal method of handling compensated cases with reference to occtqattunal disease and more tartkularly silicosis? If we examine the development uf the compensation acts we find that a technique designed primarily t< adjudicate cases of industrial accidents has by degrees hem given jurisdiction over occupational diseases. In fact, tn wmc states discuses arc regarded as injuries so that they may be brought within the scope *f the original compensation acts. Itat on close examination it becomes apparent that disease* are tar more difficult to adjudicate than are the *rdimry injuries arising in industry. They present many technical facets and rftcn require a detailed knowledge of this particular branch of mc<Brinc with which the average rommbsiuocr is very often unfamiliar. As a result we find in practice that the Cimrt is iwcsc-fited with highly technical evidence by experts for the plaintiff and for the defendant which is very difficult if not impossible to satisfactorily evaluate. Often the commissioner is caught between the conflicting views of such witnesses and is not provided with his own exirts to aid him in arriving at the real scientific background of the problem at hand.