Document 2RkDZx8wKBOk1jE75Kv1maKBa

FILE NAME: Colgate (COL) DATE: 1975 Aug DOC#: COL037 DOCUMENT DESCRIPTION: National Safety News Article - Microscopical Identification of Target Health Hazards NATIONAL SAFETY COUNCIL A NON-GOVERNMENTAL NON-PROFIT, PUBLIC Headquarters Office: 425 N. Michigan Ave, Chicago, 1L 60611 Trustees' Fund Office: 856 Lincoln Bldg. 60 E. 42nd St. New York, NY 10017 SERVICE ORGANIZATION CHAIRMAN, BOARD OF DIRECTORS OR. DEWEY F, BARICH, P rs sld .n t D etroit in stitu te o f Technology, Detroit, Mi 4S201 PRESIDENT VINCENT L T O F A N Y , National Safety Council VICE-PRESIDENT FOR INDUSTRY EmMpIlCoHyeArEsLinFs,uBr1aAncNeCAoRfDWI,auAssasuis,tWanatuVsaicue,-WPrles5i4d4e0n1t ACTING EXECUTIVE VICE-PRESIDENT FRED POTENZA, National Safety Council SECRETARY AND TREASURER H. W, CHAMPLIN, National Safety Council PRESIDENT EMERITUS HOWARD PYLE, National Safety Council A NATIONAL SAFETY COUNCIL PUBLICATION .vJ a i AUGUST 1975 VOLUME 112, NUMBER 2 55,000 copies of thisjssue were printed Future Article Preview 4 Officially OSHA 6 Voice of the Reader 8 Safetybrlefs 16 Coming Events 2B In Focus 36 62 Public Hearings on Proposed Noise Standard CRISP 42 Standards 48 64 Programming Personal Protection-- To Hear or Not To Hear (it's That Simple) 67 Noise Control . , . Diesel Compressors Product Safety Memo 52 With Safety For All 56 Congress Registration 57 OSHA-Gram 59 72 Industrial Hygiene Instrumentation-- Vinyl Chloride Monomer 8 0 OSHA Issues Guidelines for Vinyl Chloride Inspections 81 Vinyl Chloride-- Monitoring Exposures Ideas That Worked 86 Off the Job 88 Safetyclips 91 Safety Literature 108 Keeping Posted 111 84 Microscopical identification of Target Health Hazards 93 Bulk First Aid Kits (Data Sheet 651) Change of Address Card 115 Wire from Washington 150 Safety Library 170 96 Specialized Safety Manual 98 N SC Proclaims , . . With Safety For All 100 NSC Safety Training Institute Schedule for the Bicentennial Newscope 178 Obituary 182 Personnel Directory 183 New Safety Equipment 184 OSHCO 186 106 Emphasis on; Occupational Health and Protection Before Compliance Reprints 193 Advertisers' Index 196 Reader Service Card 198 iWIWECfi; A model of the human ear, used at Northwestern University's Diagnostic Center for Hearing impaired, was photographed partially assembled by James B. Lehman, NSC staff photographer. It calls attention to "Hearing Protection"-- what the recent federal hearings on the proposed noise standard were all about, (See page 62.) editor associate editors contributing editors data sheet technical director editorial director publications manager art director photographer advertising manager production manager reader card Inquiries ROY FISHER JAMES W. LAHEY SUSAN M. SHEMERDIAK EDWARD D. DIONNE DOROTHEA GUTHRIE RUTH HAMMERSMITH TOM HIRSH CHARLES PRICE HARRY N. ROSENFIELD ROBERT WATERBURY f r a n k e . Mcelroy JAMES WEGING ROBERT BELKNAP ROBERT L. MEYER JACK HORNER FRANK WASZAK JAMES B. LEHMAN JOHN C. LUNDGREN PATRICIA MAZZUCCA VICKI BACSKAI 2 STATEMENTS AND O P IN IO N S advanced in articles and advertisements ere personal expressions of the authors and advertisers, and they are net necessarily those of the National Safety C o u n c il. , . unless drey are presented a s policy statements' and are so-stated. IN FO RM ATIO N AN D R E C O M M E N D A T IO N S contained In this publication have been compiled from sources believed lo be reliable and to be representative o f the best current opinion on the subject No warranty, guarantee, n or representation Is made by the National Safety Council a s to the absolute correctness o r sufficiency o f any representation contained in this and other Council publications, and the National Safety C ouncil assum es no responsibility In connection therewith. Likewise, It can not be assumed that ell acceptable safety measures are contained In th is and in other Council publica tions. nor that other o r additional measures may not be required under particular or exceptional conditions or circumstances. NATIONAL SAFETY N E W S (so u b llsh e d monthly by the National Safety Council, and It Is printed In the U . S A Copyright 1 8 7 5 by the National Safety Council. N o material from any editorial feature o r department, u nless otherw ise stated, may be reprinted without written permission from the editor, SU B SC R IP T IO N RATES: U. S., $9 .25 a year (single copies, $1.42); Foreign: no additional charge for Canada; add $ 1 .1 6 p ar subscription lo r postage to Latin American countries, and add $1,79 per subscription far postage to all. other countries. All prices (except postage) are subject to a so per cent discount to members of the National Safety Council, and un S per cent discount to U,S. Federal Coven,uunt agencies. Quantity prices for yesriy subscriptions and single Issues available on request, MEMBER: Audit Bureau of C ir c u la t io n . ^ ^ NATIONAL SAFETY N E W S Is entered as second class postage paid at Chicago, !L, and at additional mulling offices. POSTM ASTER: Sand Form 3 5 7 2 to National Safety Council, 4 2 5 N. M ic h iga n Ave., Chicago, IL GOGH August 1975, NATIONAL SAFETY NEWS Microscopical Identification ?s48 Of Target Health Hazards Through sophisticated techniques and instruments, scientists can readily identify asbestos, lead, silica, cotton dust and other air-borne particulates in the workplace. I ndustrial h yg ien e is concerned with the s t u d y of hazards to the health of the industrial worker. Some of these hazards are tiny particles in the air we breathe. They are hard to trap and identify, and difficult to associate directly with the failure of health because many yearn may elapse after exposure before adverse effects occur. In any case, we know we have problems. Focusing upon the need to create healthful working condi tions, OSHA, in January, 1972, initiated the*T arget Health'Hazards Program. The emphasis is on five hazardous workplace substances: aibesfos, lead, silica, cotton, dust, and carbon monoride. Asbestosis resulting from pro longed inhalation of respirable air borne asbestos dust may appear 20, 30, or 40 years a ft the exposure. Other particulate hazards are cot ton dust, lead compounds, and quartz. Unfortunately, air-borne particles of these materials are so ubiquitous that everyone from fac tory workers to housewives and school children is exposed to some extent, Exposure to particulate lead compounds is common due to the use of tetraethyl lead in gasoline and in paint. Asbestos is used in filters, in sulation, fire-retardant textiles, and brake linings. Abrasion of these materials produces particles that find their way into the atmosphere. Quartz/ one form of which is silica, is the most common mineral on earth and few air samples are free of small particles of the type that may eventually cause silicosis. Cotton dust, though less of a hazard than the others, is still a potent d ang to industrial workers exposed for long periods of time to high cotton dust concentradons. The exposure time to quartz and asbestos particles must be long term, and the dosage high before serious .impairment occurs, Our lungs also have a reasonably good flushing mechanism that helps to remove the billions of particles that settle every day on those surfaces. Perhaps this capacity for cleansing the lungs must he overwhelmed for some minimal time before perma nent serious damage is done. Many varieties of technical back grounds m ust be involved before the solutions are found. The microscopist has one important- role-- By Walter . McCrone, D. Sc., Scientific Advisor, Walter C. McCrone Associates, Inc., Chicago. among others--monitoring dust and other samples for the presence and amount of the hazardous sub stances. He is able to do this be cause the microscope magnifies each particle to a size such that selective Figure 1 shows quartz (silica) particles magnified 125 times with crossed polars. Figure 2 represents cotton fibers as they appear with crossed poldrs a t 200 times magnification. Figure 3 shows chrysotile fibers (one form of asbestos) at 100 times magni fication. August 1975, HATIOKAl SAFETY HEWS with a finely focused pencil of electrons. Each time the beam strikes a tiny particle X-rays are created and emitted. If these X-rays show the proper wavelength for lead the computer stops the,., scanning sequence until "that lead- '? containing speck can be analyzed completely and quantitatively. This 'requires less than one minute for each particle. The scanning rhen proceeds to the next lead particle. Figure 4 shows electron microprobe ana lyzer used at McCrane Associates. Figure 5 shows the AEI EMMA 4 elec!ron microscope/electron probe analyzer. In one two-week period of continu ous operation the probe found and analyzed over 12,000 individual lead particles. The problem presented by water and specific physical measurements widely varying composition and borne samples is one of decreased can be made to identify that properties. Even here, however, particle sizes; most large particles particle, By selecting the proper the xnicroscopist is able to vary will have settled out. Particles microscope and utilizing his back his procedure so that fibers ob smaller than about a few tenths of ground in crystallography the micro scopist can identify many particu served microscopically Can be further identified as chrysotile, anti- a micrometer (10 millionths of an inch, for example) cannot usually late substances at sight. These in gorite, anthophyllite, tremolite, be identified by the methods de- clude most of the air-borne particles amosite, or crocidolite. Each has scribed. The microscopist can, detrimental, to our health-- quartz, unique optical properties observed however, identify these small par-- cotton fiber dust, and asbestos. Lead as optical staining colors when tides by electron microscopy and its is a special problem because there properly mounted for examination. auxiliary techniques'. The most are many different lead compounds. Figure 3 shows one of four different sophisticated of these tools is the Carbon monoxide is not detect asbestiform minerals, chrysotile. A.E.I. Scientific Apparatus Ltd. able by microscopy. Refer to the Again, individual small fibers can be EMMA (Electron Microscope October 1973 N ational Sa fety identified even when present as MicroAnalyser) (See Figure 5) It N ew s article "Target Health Haz ard-- Carbon Monoxide," for in formation regarding CO and the trace quantities in a complex mix ture. Finally, we should consider lead is a combined electron microscope and microprobe anaylzer. The identification of asbestos in water various means of detecting it. compounds. As suggested, these supplies is a good example of the First, consider the problem of identifying quartz microscopically. . The shape and optical properties make this easy. Figure 1 shows quartz between two slightly un crossed polarizing filters; the low birefringence (low numerical differ ence between the maximum and minimum refractive indices) and conchoidal (shell-like) fracture are obvious. To confirm his initial identification of quartz the micro.scopist has an optical staining pro cedure (called dispersion staining) that causes all quartz particles to appear blue or blue magenta. The latter procedure is excellent for de present problems because they are not a specific compound as is quartz, nor even a small group of slightly different compounds like asbestos. There is, however, one simple procedure that identifies all lead-containing particles as such, though it does not specifically identify the compound. The dust is dispersed (allowed to settle due to gravity) on a reagent-impregnated, gelatin-coated microscope slide. The reagent-- sodium chromate, for ex ample---reacts with lead to form a colored halo around each particle containing lead, One then simply counts the'halos microscopically to application of an EMMA, A sam ple of water is filtered through the finest membrane filter. A few square millimeters of the filter are cut out and placed on a. carbon-coated electron microscope grid. The filter itself is dissolved in a solvent vapor system, and the particles are left supported on the thin carbon film. The grid is then placed in the EMMA and scanned visually at about 20,000 times -for fibers. Each suspected asbestos fiber is then analyzed chemically in situ by the microprobe and by selected area electron diffraction (identifica tion of elements from the wave tecting traces of very fine quartz determine the number of lead lengths of their electrons), This in dust samples. particles. determines its crystal structure to Next, consider cotton fibers. Another procedure has been confirm asbestos and identify pre These, too, have characteristic used to identify the lead compounds cisely the mineral type. optical properties and shape, and in auto exhaust. The particles Microscopy is a sophisticated can be identified just as dependably spread over the surface of a highly technique for analyzing particles as quartz (see Figure 2). polished beryllium plate were ex hazardous to health, A well-trained Asbestos presents a somewhat amined by an electron microprobe microscopist with the necessary l more complicated problem because asbestos is not a single substance, but a class of fibrous minerals of analyzer as shown in Figure 4, This instrument, computer-controlled, systematically scans the particles equipment can quickly and posi tively identify and characterize suspect particles,-- End. x Hi August 1975, NATIONAL SAFETY HEWS oc ! ; i j l