Document DMGYXnxJxKnqDRrG4dMaKqrEM

FILE NAME: Asbestos Textile Product Use (ATPU) DATE: 1975 DOC#: ATPU009 DOCUMENT DESCRIPTION: Journal Article - Fibre Release from Asbestos Garments U\ G /M ia .it' I/I// . . // v ..| I* . I! \[$< i I ? t IV3 [ l , l T | M n . * l . IIC *S\ l `* 7 5 . | m : l r . | i l l ( i f t M l I I I II .11.1 , 19 *1 LIBRE RELEASE FROM ASBESTOS GARMENTS G. W. Ginns Dept. of Epidemiology anil Health anil Occupational Health anil Safely Unit. McGill University, Montreal. Canada Abstract The concentrations of airborne fibres ( 5 inn) in the breathing /ones of workers wealing asbestos safely garments were measured using the membrane filter method. At plant I where men wore asbestos coals, hoods and milieus, concentrations of fibres ranged from 0-3 to 5-0 fibres,'em' and Hie 8 hr time-weighted concentrations from 01 to M fibres,'cm'. At plant 2 where hoods, coats, mittens and leggings were worn, concentrations of airborne fibres ranged from 9 0 to 26 2 (ibrcs/cm3and the 8 hr lime-weighted average concentration was 4-7 fibres,'em3. Counts of fibres collected on Nuelepore filters and examined by scanning electron microscopy showed that the concentrations of fibres 5 uni in length represented 2T 12 per cent of the total airborne libre. The dilVeiencc between the quantities of fibre released from the garments at the different plants was probably related to the methods or materials used in garment manufacture. The results showed that there is a need to identify and to reduce the release of fibre from asbestos safety garments currently supplied to protect persons working in hot environments. IN T R O D U C T IO N Tests of industrial-type asbestos aprons and gauntlets in the laboratory (Bamih-r and Butterworth, 1970) have shown that concentrations of asbestos near the breathing zone of a worker can exceed the current British (Buriisii Occupationai. Hygiene Society, 1968) and proposed US standard (O re. Sai-l-ty and IIi ai.iii Administration, 1972) of 2 libres/cm3 lor chrysolite and amosilc asbestos. Fibre concentrations associated with the wearing of new unlined asbestos cloth fire-fighting helmets have also been shown to exceed 2 libres/cm3(I.umlhy, 1971). The concentra tions of asbestos to which industrial workers wearing asbestos safety garments at their place of work are exposed, and hence the potential hazard for such workers, have not been previously reported. The objective of the present study was to provide such information. M ATERIALS AND METHODS Population for study The study involved men employed at two ore reduction plants where asbestos safely garments were worn routinely. The first survey was conducted in the blast furnace section of a large steel plant (plant 1) where ore for reduction was fed con tinuously to four furnaces. Five men were normally assigned to each furnace and all workers on two neighbouring furnaces were chosen for study. As the work on each furnace was fundamentally the same, neighbouring furnaces were chosen for con venience. The men working on these furnaces prepared channels along which molten iron (lowed, tapped the furnaces and kept channels clear of slag during casting. Castings were held at approximately 4-ltr intervals and lasted i-T] hr. Men generally wore asbestos safety coals lor the duration of a easting but hoods and gloves were worn for varying periods as necessary. Address for reprints: Dr G. VV. Gibbs, 3775 University St.. Montreal, Quebec, Canada 143 lit G. W. Gums The mvoiuI survey was coiulacted al a small plant manufacturing elemental phosphorus (plant 2). I'onr men were responsible lor two furnaces which operated continuously. Slagging operations (i.e. tapping the furnace) were performed at approximately I 1J-hr intervals and lasted 15-45 min. I he work was similar to that at the steel works. Asbestos safety coats and leggings were worn throughout the slagging operations blit hoods and gloves were worn only when necessary. Men employed on two shifts were studied. Asbestos garments The asbestos garments worn by men in this study, as far as could be ascertained, were from three sources. Information and properties of the cloths from which gar ments were manufactured are summarized in Table 1. In spite of extensive inquiries, it was not possible to obtain full details of the cloths from which garments were i manufactured in all cases. This was due to the fact that manufacturers bought cloth 'i 6 from more than one supplier and it was not always possible to identify the individual coats used by the companies. Estimates of the age of the garments were obtained from each man tested. T am e I. Materials used for manufacture of asbestos c.arments Coats Hoods Mittens Weight Grade Weave Treatment Weight Grade Weave Treatment Weight Grade Weave Treatment Comments Leggings Weight Grade Weave Treatment Plant 1 Garments--Source A 2 5 Ib/yd2 Underwriters'' Plain Nil 1-2 Ib/yd2 Underwriters Herringbone Aluminized outside 2-50 Ib/yd2 Commercial Plain Nil Knit flame proof cuff, chrome leather, green tanning--palm and thumb Not worn Plant 1 Garments--Source B 2-5 Ib/yd2 Underwriters Plain }% Acrylic resin based on weight of cloth 1-2 Ib/yd2 Underwriters Herringbone Aluminized outside 2-50 Ib/yd2 Underwriters Plain j Acrylic resin based on weight of cloth Plant 2 Garments--Source C 2-25-2 50 Ib/yd2 Underwriters Plain and herring bone Nil 2 25 Ib/yd* Underwriters Basket Dust suppressed! Aluminized outside 2-25 2-50 Ib/yd2 Underwriters Plain and herring bone Nil Not worn 2-50 Ib/yd2 Underwriters Basket Dust suppressed * Underwriters--80-85 % asbestos. + These hoods were manufactured from heavier cloth than normally encountered in industry and the aluminized layer had a different appearance. 4 I line release from asbestos ii.irmenls MS ( nl!ri imn of airborne fibre samples Airborne samples of d u st were collected using calibrated personal monitors which wrie attached to llie employee in such a way as not to interfere will) his work. I he open-laeed filter was located in the employee's breathing /one, outside the asbestos coat but under Ihe hood when worn. Samples for optical fibre counts were collected on Millipore 37 mm (type AA, pore size OX ini') and a number of samples for scanning electron microscopic examination were collected on.Nuclcporc (type CiE-40 pore size 0-4 pm) filters. Sampling rates were approximately 2 l./min. The sampling period was the total lime from the start to finish of a slagging operation. It was not possible to collect samples of ambient air in the work areas as safely regulations at both plants did not permit persons other than the employees in the work area during a east. However, we were assured by management and research departments that there were no other sources of fibrous dusts. Counting o f airborne fibre samples (a) Optical counts. Millipore membrane filters were mounted and counted using the method of the B ritish O ccu pa tio n a l H ygip.ni: Society (1968). Fibres greater than or equal to 5 pm in length and with length tbreadth ratios greater or equal to 3:1 were counted on a,Zeiss WL standard research microscope at a magnification of 400 x using phase contrast. At least 20 fields were counted on each filter and the same observer counted each sample twice. (b) Scanning electron microscopy. Airborne samples of dust collected on Nuclcpore filters were examined by scanning electron microscopy (SEM) as follows. Circular segments (13 mm in diameter) were cut with radii touching the centre of the 37 mm filter and were attached by adhesive tape to standard 13 mm SEM mounts. Samples were coaled with 150 A layers of Au-Pd and scanned at a magnification of approxi mately 6000 x on a Cambridge Stcrcoscan type 96113 Mark 2A setinning microscope. Scans were performed across the diameter of the spacement and photographs of random fields were taken. The field area ranged 257-265 pm2. Both the total number of fibres and those with lengths greater than or equal to 5 pm were counted, Storeys (a) Studies at plant I. Day 1 (Pilot study)--All men wore asbestos coats, gloves and hoods issued by the Steel Company (Source A). No leggings were worn. Details of the garments are show n in Table 1. Day 2--All men wore asbestos coats, gloves and hoods issued by the Company and these were identical in appearance to those used during the previous survey. Day 3 - Four men w'ore garments as described for Day 1 and Day 2. The other employees were issued with new' coats, hoods and mittens (Source B). The specifica tions are shown in Table 1. (b) Studies at plant 2. Men at this plant wore asbestos coats, leggings, gloves and hoods supplied by Source C, shown in Table 1. RESULTS Optical counts The pilot investigation at plant 1 showed that fibres could be discerned against the dark background of graphite and magnetite particles present in the work area. I his bachunuimi made counting more difficult Ilian when n was not present but the asbestos iibres could still be identified and counted. As there was no obvious reason why counts obtained on samples collected in the pilot investigation at plant I should he clillcrcnl from those obtained in subsequent surveys at the same plant, the results were combined. At plant I, the concentrations of fibres > 5 pm in length in the breathing zones of men wearing asbestos safety garments of various ages and sources are shown in Table 2. The mean concentration for 39 tests was 2-0 (ihres/cm3 (s.i.. - 0-4). The concentration m one case reached 5 fihrcs/cnr1 for a mean exposure time of 54 min. T a iu .i 2. M i a s iik io c o n c i:n i h a iio n s a n d timf.-w i u .i o i n c o N n n i k m i o n s oi a ik iio k n f iiiik f s IO W H IC H M I N WFAIUNO AS I l l s HIS S A I T I Y CIAKMKNIS A l l- I A N I I W'lKC I M 'OSII ) Source of garment /X B Total Age of garments (weeks) Mean exposure period for slagging operation (min) New ( 1 week) 49 1 4 weeks 52 4 weeks 51 New ( < 2 days) 54 52 Number of samples 4 15 5 16 39 Measured conccntraiion (fibres/env1) - -----Mean Range II 0 7-1-3 1-7 0-5 3-7 2 0 0 6 2-6 2-4 0-3 5 0 2 0 0 3-50 Dailv exposure period (min) Mean Range 8-lir wc ighied concentration (fbres/cm, ) --------- Mean Range 98 82-114 104 50-144 102 70-130 108 62-128 0-3 01 0 3 0 3 0 1 0-8 0 4 0 1-06 0 5 0-1-t-t 103 50 144 0 4 0-1-1 -1 To investigate the effect of age on fibre release, the results of the lirst lest on all coats issued by plant I were plotted against the age of the garment. The linear correlation for all results was 0-4. When the result for the 12-wcek-old coat, which was similar to that for new coals, was discarded the linear correlation between age and fibre concentration increased to 0-68. This suggested that the fibre release increased with age of garment up to S weeks. However, the scatter was great, the number of measurements was small and the correlation coefficient too low to reliably predict fibre release from garments of different ages. In 13 tests, the conccntradion..ecftcdcd. 2Jjbres/cm \ When the length of exposure for men wearing safety garments was calculated for an 8 hr work-day (assuming the usual work practice of two casts per day) the overall mean concentration to which they were exposed was 0-4 (ibres/cm3 with concentrations ranging 01 --11 fibrcs/cm3 (Table 2). In no case did the 8-hr weighted exposure exceed 2 fibrcs/cm3--the standard adopted by the B ritish O c cu pational H ygiene Society (1968). Rrcathing zone concentrations were similar for men with different occupations (Table 3), indicating that no individual operation was giving rise to fibre release seriously different from the others. .At plant 2, the breathing zone concentrations of fibres (> 5 pm in length) exceeded 5 fibrcs/cm3 in all cases and in all but one case exceeded J O fibres/ cm3 for exposure pcriods.ranginc 15--47 min (Tabic 4). Slagging operations at this plant were performed at 1--1-hr intervals and lasted 15-47 min. It was therefore r I lino idouse from asbestos garments 1-17 1 Mil 1 ( UNI T V 1R A I lo v s Gl A1K111IKIN1. ASIII SI OX >1I1KIS IN rill llltl AIMIN'. /.INI.S il l M IN W IS H IN G ASItl SIT IS G ARMEN IS BY OC'PU PA TIO N . Pi a n r 1 ( Kcupalion Number of samples Concent rut ion (lilires/cur'l Mean Range keeper 1lot bl.i'.lniim 1 list helper S e t.oml lielper Third helper Miscellaneous <) 1-7 0 5 50 3 2-7 0 5 4-6 5 2-2 0-3 3 7 7 2-5 0-7-4 0 6 1-9 0 8 -3 -5 9 1-6 0-5 3-7 Total 59 2-0 0 3 50 ,, possible lor men to perform as many as five operations per shift and to wear these coats an average of 2 hr 45 min per day. Based on this exposure lime, the 8 hr timeweighted average exposure would have been 4-7 libres/cnr1. I M il.I (. CVlNCENTRA I IONS OF A1Kill111N I- ASBESTOS IM R E S MEASURED IN TH E IIREATHING ZONES OE M IN W EARING ASIIISTOS SAFETY GARMENTS AT IM.ANT 2 Sot lice of garments Age of garments (weeks) Mean exposure period (min) Number of samples Concentration (fibres/cnr1) Mean Range Source C 1 week 39 1 4 weeks 28 : 4 weeks 38 2 12 8 10 6-15 1 2 18 1 9-9-26 2 2 12 3 10 6 14 0 Total 35 6 14-1 9-9-26-2 Concentration o f fibres including submiiroscopic fibres The total airborne concentrations of fibres greater or equal to 5 pm in length counted from scanning electron micrographs are shown in Table 5. The concentra tions of airborne fibres > 5 pm in length as percentages of the total airborne fibre concentrations were 32. 16-5. 2-3, 26, 28 and 23",, respectively. In order to estimate the percentage of fibres 5; 5 pm in length which were not counted by optical methods (due to narrow diameters), the concentrations obtained by optical and electron microscopic methods were compared (Table 5). It must be noted that, I A 111 I 5 , C o N iT .N IRAT ION O l AIRBORNE ASBESTOS I HIRE. AS DETERMINED IIY SCANNING IT.ECTRON- M ICROSCOI'IC EXAMINATION Ol N U C E E PO R F MEMHRANE FILTERS (N) AT 6000'- MAGN. AND OPTICAL EXAMINATION OE MILI.IPORE MEMBRANE FILTERS (M) AT 400 Airborne fibre concentrations (fibre/cm3) Soutec of garment Age (weeks) SEM count on Nuclepore filter (N) -- -- Total fibre Fibres > 5 urn length A 8 100 32 A 1 109 IS A 3 869 20 H New 230 61 C 8 341 96 C Coat 3 216 51 Mood S * Sample for comparison lost. Optical count on Milliporc filter (M) Fibres > 5 pm 4-0 _* 0 5 2-9 10 6 26-2 M/N. 12-5 2-5 4-7 11-0 510 I i 14S G. W. Glims although the samples which were compared were obtained on the same man wearing the same garments, they were not taken simultaneously. I his probably explains the large variation in the ratios of optical counts to electron microscopic counts of fibres fi /.m. Nevertheless, the electron microscope counts indicated that substantial numbers of fibres ^ 5 |im in length were present in the airborne dust which were not visible by optical methods. v D IS C U S S IO N 1he mean concentrations of airborne asbestos fibres measured in the breathing zones of workers wearing asbestos safety garments at plant 1 were similar to those reported by Lumi ky (1971) for men wearing new firefighting helmets with unlined asbestos cloth covers (2 3 libres/cm3) but lower than those reported by Bambf.r and Butit.rw orth (1970) (mean 3-5 libres/cm3) who tested an undefined type of protective clothing in a laboratory study. In (his present study, it was not possible to determine whether the airborne fibres originated from the coat, gloves, or hood, as hoods were worn only intermittently. In all but one case, the concentrations of fibres in the breathing zones of men wearing coals from sources A and B were below the threshold limit value of 5 fibrcs/cm3, currently adopted in (he U .S.A . (Ore. Safety and Hi ai.tii A dm inistration, 1972), but one third of the tests exceeded the standard of the B rm isii O ccu pa tio n a l H ygiene Society (1968) (2 libres/cm3). The timeweighted average concentrations to which men were exposed for the particular operations studied at plant I were all less than 2 libres/cm3. The concentrations of fibre in the breathing zones of men employed at plant 2 were high, exceeding the excursion level of 10 fibrcs/cm3 permitted in the U.S. Standard. The reason for the difference between the quantities of fibre released from these garments compared with those at plant I is not known. However, both coats and mittens at plant 2 were untreated and leggings were also worn. The coats were observed to leave asbestos on the men's clothes when removed. It would seem advisable that garments which release fibres readily should not be used until a method of reducing their fibre release has been found. C O N C L U SIO N In conclusion, there is a need to identify and decrease the fibre release from asbestos garments to prevent exposure of workmen to concentrations which may be considered hazardous to health or exceed present and likely future standards. This should be done by developing new processes for manufacturing and treating (or coating) asbestos cloths and by testing garments for fibre release before distribution for sale to industry. Such tests should take into consideration the release of submicroscopic fibre. Acknnnlcilncmcnts I acknowledge with thanks the assistance of Messrs II. Hui. M.Sc.. A. Corsillo 1 and P. Schafer, who conducted the field surveys and performed the fibre counts. M rC. Y. Hwang, M.Sc.. who was responsible for the electron miscoscopie studies, the companies who provided access I to their plants to conduct the study and the workers who participated. This research was supported by a grant from Raybestos Manhattan Inc. li mp luins ts of miai j not I il'ii- release from asheslos jmi 1111:111-. 140 l<I I I K I- Nr I S It Mill it. II A. mul Uni il KWi'Kin. H. (10 70), Iini. iirn ip . Il\ y . 1.1, 77 SO. IIkiiisii Oi l ri'MiiPsAi IIw.iini Si 11 iv (IO6K1 Inn. occtip Uyg. 11,47 40. I i in iv, K. I'. S. (IV/11 . iun. (icaifi. Ily.i;. 14. 2NS 2K6. O r . Sai I IV and III \ i m A dminisik aiion (1072) O e a 1piiti011.il Salely aiul Ileali li Slauilaiils. Standunl loi l-sposiire lo Asbestos Oust. Ini. Keg. 37, Tille 2'*, (T'K. pail 1010, 11318 11322.