Document oD61qwyzgYMZee382KywbVk6D

FILE NAME: Asbestos International Association (AINT) DATE: 1977 Aug DOC#: AINT018 DOCUMENT DESCRIPTION: Published Summary of International Colloquium on Dust Measuring Technique and Strategy [Note - Many originals are on legal size paper so text looks small when reprinted on 8.5x11 paper] Arbeits- und Umweltschutz INTERNATIONAL COLLOQUIUM ON DUST MEASURING TECHNIQUE AND STRATEGY AT WARMENSTEINACH GERMANY I ON AUGUST 29 AND 30, 1977 1 I ADDRESS: GRLITZER STRASSE 1, D-4040 NEUSS, TELEFON 02101/13051-53 TELEX 8517402 au d t 1 I. list of participants AUSTRALIA M r . G . Ma jo r , School of Public Health & Medicine The University of Sydney B u i lding A 27 New South Wales 2006 Tropical Mr. G.C. Pickford, Wunderlich Limited O'Connel St. Sydney Mr. J.W. Winters, James Hardie 65 York S t . Sydney & Coy.Pty.Ltd. ] AUSTRIA H Mr. Bigga, sterreichische Staub (Silikose) Bekmpfungssteile Technische Abteilung Postfach 72 8700 Loeben Mr. S c h m i e d i n g e r , E t e r n i t - W e r k e L. H a t schek 4840 Vcklabruck BELGIUM M r . van Her le , Eternit S .A . 2920 Kapelle-op-den-Bos CANADA Mr. G. Gibbs, M .S c .P h .D .,O c c u p a t i o n a 1 Health and Safety Institute for Mineral Industry Research McGill University, Gault Estate Mount St. Hilaire, Montreal, Que. L_.J SWITZERLAND Mr. Kiinzler, SWEDEN Mr. F. Danstrand, Mr. N. H a l l i n , jjMr . S. Skyllberg, UNITED KINGDOM Mr. A.A. Cross, Dr. G. Leguen, Mr. R.M. Wagg, M r . W .H . W a 1t o n , 4 Schweizerische anstalt Fluhmattstr. 6002 Luzern Unfallversicherungs ' C.A. Clase AB Ruskvdersgatan 8 417 Gteborg Organisation for Industrial Safety and Health in the Construction Industry Burgghlsan _ Fack 10041 Stockholm Swedish National Board of Industrial Safety Fack 10026 S t o c k h o l m 39 Asbestos International 68, Gloucester Place London WlH 3HL Association Research & Service Laboratory Division Health & Safety Executive 403/405 Edgware R d . Cricklewood . London NW 2 Health & Safety 403/405 Edgware Cricklewood London NW2 Executive Rd. Institute of Occupational Roxburgh Place Edinburgh EH8 9SU Medicine USA Dr. G. Chase, Mr. F.A. Madsen, Dr. Rhodes, Dr. Y . Hammad, 5 J o h n s - M a n v i 1 le C o r p o r a t i o n Health, Safety & Environment Department Greenwood Plaza Denver, Colorado 8 0 2 1 7 OSHA Occupational Safety and Health Administration 390 Wakara Way Salt Lake City Utah 84108 Lnxon Carbide Corporation P.O. Box 579 Niagara Falls, N.Y. 14302 Tulane University School of Medicine Pulmonary Disease Section New Orleans, La 70112 6 II. * s UMMARY According to an agreement of the Executive Committee of the Asbestos International Association Dr. Robock organized a colloquium on DUST MEASURING TECHNIQUE AND STRATEGY with cooperation of Professor Gibbs and Mr. Walton The aim of this colloquium was . to establish the differences of dust measuring technique and strategy within the different countries . to achieve an international stand a r d i z a t i o n which enables us to compare the situations in the plants within the asbestos industry and which gives us the basis for epidemiological studies (retrospective and prospective) The colloqium took place at W a r me n steinach, a small town in the National Park Fichtelgebirge (Bavaria), on Au g u s t 29 and 30, 1977. Invited were representatives of the asbestos industry and the c o n t r o l l i n g authorities. 39 experts from 15 countries participated. After an introduction by Dr. Robock in which he illustrated the necessity of a standardization the following topics were discussed: - Techniques and strategies applied - Results from scientific and practical dust measurements - Presentation of dust measuring data - Automation of fibre counting A convention for the standardization of method and strategy could not be reached in the shortness of time beca u s e of numerous d i f f erent opinions. Dr. Robock was asked to convene a Dust Working Group to prepare such convention. In the following a summary of the presentations and individual contributions: TECHNIQUES AND STRATEGIES APPLIED MR. TEI CHERT reported in his presentation EQUIPMENT AND STRATEGY OF DUST MEASUREMENTS WITHIN THE GERMAN A/C INDUSTRY about the functions of the German asbestos cement (A/C) industry, the measuring instruments applied and their principles and limits, kind of sampling, selection of measuring points and measuring p r o cedures as well as about preparation, counting and of average values based on individual results. 8 Those measuring series were reported about which demonstrate the problems connected with each complex and the measures taken (e.g. way of handling e q u i p ments) were explained on the basis of results. MR. WALTON mainly referred in his<presentation PROBLEMS IN THE STANDARDIZATION OP ASBESTOS DUST MEASUREMENTS to the membrane filter method. He pointed out that it is the purp o s e of s t a n d a r d i z a t i o n - to enable information from different sources to be compared and collated into one general pool of k n o w l e d ge ; - to ensure that specified limits (TLV's, MAK's) can be uniformly implemented to provide the intended levels of safety. To be effective, standardization must cover not only the evaluation (counting) of samples, but also the method and strategy of sampling, e.g. the shape and orientation of the filter holder, the sampling air velocity, when and where samples are taken, whether over a short period or over the whole shift, whether in the b r e a t h i n g zone or in the general environment, etc. The h y g i e n e standard for asbestos in B r i t a i n (2 F/ml) was derived from epidemiological evidence in an a s bestos factory where environmental measurements have 9 been regularly made since 1953. At first sampling was by thermal p r e c ipitator and all particles (not restricted to fibres) were counted. Then a new i m proved form of thermal precipitator was used, and finally there was a change to membrane filter methods when fibres > 5 pm were counted. All the counting of fibres on the membrane filters was by the so-called full-field-method", i.e. with no graticule in the microscope eyepiece to define the counting area. Meth o d s have since chan g e d further. The standard is applied to personal sampling whereas it was derived for fixed position sampling, and to counting with a graticule which gives much higher values than fullfield counting, and to single shifts whereas the derivation was based on long-term average levels. Thus, it seems probable that the standard now being enforced is appreciably more stringent than was i n tended. Mr. Wa l t o n repor t e d about e x p e r i e n c e regarding c o m parative countings. The influence of the graticule on the counting result was pointed out and a graticule specially concipated for the fibre counting was presented. This graticule allows an exact determination of countable fibres. The r elatively great d i v e r gencies in comparative countings can substantially be influenced by different detection limits of thin fibres. The limitation not only to a maximum diameter of fibres but also to a minimum diameter could be helpful. r '1 I J ] J J i 1 J "1 J i -j "n i 10 Tf the ratio length to d i a meter would be inc r e a s e d from 3 : 1 to 5 : 1 the number of asbestos fibres would not be affected but all elongated mineral fibres could be excluded. A standardization should not only be an agreement between the evaluating people but also the biologists should b e - c o n s u l t e d to examine if the right r e s p o n sible parameters are measured. Concerning this matter the biologists have still to answer a lot of open questions about relevant parameters for the different types of reaction - fibrosis - mesothelioma - lung cancer - other tumors The two presentations and the contributed papers have d e m o n s t r a t e d that the m e m b r a n e filter method is h a n d l e d in very different ways with regard to important details. This can lead to different and not comparable results. TECHNIQUE - SAMPLING . velocity at the suction aperture . flow rate check . pressure constancy (pulsation) . time (overloaded filter) (mm/sec. - m/sec.) - 1 1 - FILTER . type of material (nitrocellulose, acetate) . pore width . diameter . surface (with and without grid) cellulose PREPARATION . embedding medium (refractive index) e.g. triacetine, US-mixture, cyclohexanone, acetone vapour and thus influence on .. d e t e c t i o n limit .. b a c k g r o u n d ' .. t h i c k n e s s of the layer of dust .. p e r m a n e n c y . way of handling the medium, the filter and the r cover slip and storing of the prepared slides COUNTING . microscopic equipment .. p hase contr a s t device .. i l l u m i n a t i o n .. filter .. m a g n i f i c a t i o n .. gra t i c u l e thus influence on detection limit and size determination '' COUNTABLE FIBRES .. length .. diameter .. ratio length : diameter .. a g g l o m e r a t e s .. s p l itted fibres 1 J J .1 J --1 1 J 3 3 .3 3 J 1 J 1 J 3 1 "1 J 12 - STATISTICAL PRECISION .. c o n s i d e r a t i o n of fibres o v e r s t e p p i n g field of counting .. total number of fibres to count .. number of fields of counting to evaluate .. over l o a d e d filter STRATEGY ^ - FUNCTION engineering control . exposure control - SELECTION OF MEASURING POINTS . some points distributed over the hall . all workplaces . all workplaces with dust exposure POSITION . stationary . personal ... on the person .. following the person . consideration of influencing factors (draught, working conditions) DURATION . short-time . long-time STATISTICAL PRECESION . number of samples . repetition working cycle - 13 - CALCULATION . peak concentration . arithmetic average . time-weighted average RESULTS FROM SCIENTIFIC AND PRACTICAL DUST MEASUREMENTS PROFESSOR GIBBS p o i n t e d out in his p r e s e n t a t i o n RESULTS FROM SCIENTIFIC AND PRACTICAL DUST MEASUREMENTS that dust measurements should serve ' - to prove the compliance with standards - to identify dust sources > - to test the effectiveness of control measures j k - to improve our knowledge of the relationships L b e t w e e n a s b estos dust exposure and its h e a l t h effects. Given that a standard is set, it is the r e s p onsibility of the government or agency promulgating this standard to set it out in clear terms, to describe and designate the appropriate instrumentation for collecting the sample, the calibration, its operation location and frequency of sampling, tolerances on the measurement and the way in w h i c h m e a s u r e m e n t s are t o - i n t e r p r e t . To identify dust sources in recent years a number of in struments based on light scattering, piezoelectric effect, -ray absorption etc. have been deviced for the rapid measurement of airborne concentrations of dust. Such methods cannot distinguish between asbestos fibres and other dust, but as relative m e a s u r e m e n t s they can be very helpful, for example to test the 14 effectiveness of control measures by checking before and after modification at a site. A l t h o u g h the exposure to asbestos is related to 4 main diseases very little is known about the risks dependent on the level of exposure. The available data on dust c o n centrations in the past was determined by methods which deviate from the currently applied membrane filter method. It is therefore essential - to find methods to convert past environmental data to the equivalent fibre concentrations to determine whether standards which have been set, based on the membr a n e filter method, have validity in scie n t i f i c terms, - to consider carefully and determine whether this meas u r e of airborne fibre c o n c entration is an adequate index of environmental quality for the control of each of the diseases associated with asbestos exposure, - to conduct more studies of exposure-response. The participants contributed data from the past and present for the various branches of the asbestos industry. Since m many countries they have only just began with measurements in the last few years a very limited amount of data was presented. In most of the cases values could only be indicated to some striking workplaces. This does not enable us to derive a representative cross-section for the whole industrial branch but it gives a rough idea of the order of m a g nitude of the - 15 - fibre concentrations in the past and at p r esent in the different industrial branches: FIBRE CONCENTRATIONS (F/CM3) MINES minimum maximum majority former - today 0.1 1 0.5 MILLS minimum maximum majority former 10 200 20 - 100 today 1 .5 100 5-10 INSULATION INDUSTRY (production and appli< former today minimum maximum majority 5 1000 40 - 100 2 200 5-50 TEXTILE INDUSTRY former today minimum maximum majority 5 300 50 - 200 0.5 18 1 - 5 ] J ] J j J 1 Ji j "I J j 1\ -i ] 1 J J A/ INDUSTRY minimum maximum majority 16 former 4 1 50 10 - 50 today 0.1 5 0.5 - PRESENTATION OF DUST MEASURING DATA MR. THIELE reported in his presentation PRESENTATION OF DUST MEASURING DATA about the way of proceeding in the Danks E t e r n i t Fabrik A/S. The results of measurements serve to inform the worker and the management. In order to be able to discuss the situation with the worker the results must quickly be available, i.e. as long as the worker can still clearly remember the working situation in question. For the m a n a g e m e n t a general survey is p r o v i d e d i n d i cating the number of employees exposed to dust. 4 groups with different exposure levels are formed > 1 f/cm3 > 2 f/cm3 - > 3 f/cm3 . > 5 f/cm3 The remaining employees are exposed to a dust c o n c e n tr a t i o n of ( 1 f / c m 3 . If this survey is kept over a longer period the positive development of the dust situation can be realized at once. 81 MR. A.A. CROSS (10) Example of group of factories and operations comprising Asbestos Cement Manufacture (sheets, pipes, fabrications Asbestos Insulating Board -- not pressure pipes) Friction Materials Thermal Insulation Materials Application of Asbestos and other Insulating Materials (including spray) Stripping and repair of Insulation 1. P r ogramme of A s b e s t o s Dust C o n c e n t r a t i o n Measurement. 1.1. Method - Membrane filter method in accordance w ith ARC Te c h n i c a l Notes 1 and 2. 1.2. Sampling Period - 10 minute periods c o v e r i n g period of maximum dust emission. Multiple samples (usually two) when significant variation from expected (from previous records). Longer periods (representative of con tinuous shift operators) up to 4 hours are c a r r i e d out when 10 min. samples indicate concentration ^ 2 f/ml. 1.3. Sampling Locations - Operator's breathing zone (OBZ). N o r mally by lapel mounted sampling head. Alternatively, with sampling head on probe, held in OBZ by sampler following operator's movements. Machine Counts (MC). -Measurements at point of emission (dust emission source) by static sampler. Backgr o u n d Counts (BG). Measu r e m e n t at p r e d e t e r m i n e d locations in w o r k s h o p area to determine condition of general working environment. 1. R e s p o n s i b i l i t y . (1) C o n t i n u o u s p r o g r a m m e of m o n i t o r i n g carried out by local technical staff of * % Results. 82 operating company, often associated also with quality control. Reports monthly to local mangement and to h e a d quarters service chief. All measurements exceeding 2 f/ml subject of immediate special report to plant management for investigation and remedy. Monthly summary of such reports presen ted to senior mangement (board of direc tors) by director responsible, with in formation on action taken or planned. In cases of sustained excess dust level, ' sampler has authority (through workshop management) to stop the offending process. (2) Ce n t r al E n v i r o nm e n t al Service (re sponsible to parent company board) makes twice yearly visit to carry out parallel dust measurement. This ensures continuous correlation of sampling and evaluation techniques, and confirms reliability and consistency of reports. It also provides opportunity for advice and communication on control techniques. (3) C e n t r a l E n v i r o n m e n t a l Service is r e sponsible for establishing techniques of sampling, for specifying equipment, for training, and for supplying emergency and investigatory facilities within and out side the organisation. (4) By liaison with associated members of ARC and with the technical branch of the Factory Inspectorate, the Central Environ mental Service endeavouring to maintain consistency of measurement with other experts. The effect of constant and planned moni toring in reduction of excessive dust c o n c e n t r a t i o n is d e m o nst rated by the following comparison. Percentage of Measurements in different Levels of Concentration 1971 1976 < 2 f/ml 2-4 f/ml 4-12 f/ml > 12 f/ml 52.3 22 . 1 18.9 6.7 88.3 9.5 2.2 -