Ra art. 153 Exposure to Asbestos during the Servicing or stakes or gr: .I In}! g9su n: 1-: Hickiah - 1/163 Industrial Hygiene Specialiat 811226 PWOPERTY CF FORD PRODUCED BY FORD FAFDOO1OB1 1 PRODUCED BY FORD FAFDOOEIDIDEII II INTRODUCTION FIELD INVESTIGATION This investigation was undertaken in View of the increased national concern.regarding exposure to asbestos. and of the impending revision of the Asbestos Regulations of the Ministry of Labour. One of the operations within the motor industry which could involve exposure to asbestos dust is the cleaning of brake drums and clutch assemblies. normally carried out during routine servicing by ?blowinguest' with compressed air jets. The brake linings in current use may contain 60 to 60$ asbestos when sanufactured a the asbestos being normally in the torn. and occasionally in the amoeita term. Crocidolita asbestos is said not to be used. it was considered that any hazard to health from exposure to brake?drum or clutch dust would be more widespread within the Dealer Repair Organisation than within Ford of Britain. so the initial investigation was carried out at a large Main Dealer service hey. it this garage. the number or cars per day given a routine service vcries betWecn 10 and 20, but not all servicing involves brake cleaning. Air sampling was carried out initially on two occasions. A and B. using thermal precipitators lT.Psl as the sampling instruments. 0n the second occasion. samples were This latter technique has been developed in recent years. and is likely to become also collected on membrane filters. the preferred method of coupling for asbestos in Great Britain and the U.5.A. 0 0 4L PROPERTY OF RE FORD Halon COHPANY pnooucco sv FORD EH "lugs. FAFDOO10812 PRODUCED BY FORD FAFDUUDDWBIZ 5 In each measurements were made: By the side of care being given a service which included brake cleaning.I and lb) In the duet-cloud during brake cleaning. and then near to the car for the remainder of the service period. he the mechanic normally blows the duet away from himself. the sampler at would be exposed during 'hlow-oif' to dust concentrations greater than those actually pertaining at the breathing zone. It was considered. howeVer, that to eample in this way would provide an additional factor or safety. Details of the sampling are given in Table 1. A further period of air sampling. C, was carried out. when membrane filter samples were collected from the breathing zone of the brake?clean operative. by means of a personal sampler. with suitably modified flow rate (approx. 250 cc/min.l. The sampling covered an entire work shift. during which brake blow?out was carried out on the following Vehicles: 5 Coreairs 1 Zodiac 4 Cortinae 611222 1 Protect The thermal preoipitator slides were subsequently incinerated and examined by micro-projection note; a 4 mm objective and X.17 eyepiece. The membrane filter eanplee were rendered translucent by the addition of triaeetin. and examined in a similar manner. Phase contrast microscopy was not need. . The results of the T.P. counts for occaeione A and are givon in Table 2. and [or the membrane counts on the I occa?i?ns FORD MOTOR company FAFD0010813 PRODUCED FORD FAFDUDOGIHBEB . occasions and in Table 3.. The counts are expressed in I terms of particles with diameter greater than 1p. and of tihres li.e. particles with aspect ratio greater than 3:1 and length greater than 5p]. 111 In View of the relativaly few fibres present in the air samples. a laboratory inVeetigation was undertaken. comprising microscopic examination of samples iron brake lining material [which was filed to produce dust] and brake drum duet [collected by spatula from brake drums immediately prior to blowing-out]. The samples were through a?O-meeh screens and then examined before and after incineration. The results are shown as fibre proportions g. in Table 4. Samples of material collected from the brake drums of [al an Anglia van. [bl a Mark II Cortina. and an Anglia car were analysed by Dr 5 Holmes of Mesars.Turner Brothers Asbestos Co.Ltd.. and his_findinga are shown in Table 5. IV DISCUSSION OF RESULTS in) Standards of dustiness In June 1968. the British Occupational Hygiene Society published a Hygiene standard for Chryaotile Asbestos Duet. which suggested that in order to reduce the risk of contracting asbestosis to 1% of those with a lifetime?s exposure to the dust. the accumulated exposure Should not exceed 100 fibre-years/cc. i.e. 2 fibres/cc for 50 years, or 4 fibres/cc for 25 years. In this standard. fibres are lea defined B11223 Peoneetv 0; FORD ROTOR COHPANV ?wim?mu,1,?n,3wm,uemb .. Lanes . FAFD001 081 4 PRODUCED BY FORD FAFDGOOD - 4 - defined as those exceeding in length. as detemined by the membrane filter method. Categories of dustinees are designated as follows: Dust Categogx Concentration avers over 3 months [Fibres cm Negligible 0 - 0.4 0.5 1-9 Medium 2.0 - 10.0 High Over 10.0 As an alternative index, a therlel precipitator count of 25 particles/cc greater than in after incineration is regarded as equivalent to 2 fibres/cc by membrane filter count. While it is considered unlikely that a mechanic will be engaged on broke cleaning for a working lifetime of up to 50 years. an additional factor of safety should be provided if Threshold Limit Value of 2 fibres/co. i.e. corresponding a - . i. I . viva. - to this length of exposure. is adopted in considering the :21: results of the present air sampling. [bl Field investigation The thermal-precipitate: particle counts are in excess of the alternatire TLV of 25 particles/cc. but these counts would include many non-asbestos particles - road dust eto., whereas the TLV wee determined from counts within asbestos factories. The fibre counts by thermal precipitate: are lower than those obtained by membrane filter.-.. . 1' - - I . -.- ..-.-. - - - I Membrane filter counts show a concentration in the A. ,l 1 .I. general atmosphere below the TLV, except when the sampler is a-?i placed in the dust cloud during blow-out. The personal exposure 611224 PROPERTY OF FORD MOTOR COPPANY FAFDOO1DB15 PRODUCED FORD I occur during brake drum blow-out in?a typical Dealer 311225 exposure is shown to he at a level of 1/3 of the TLV, and corresponds to a 'low' dust category. [cl It is. at first sight. surprising that the exposure to asbestos is as low as found. in view of the quantity of asbestos present in the original material of the brake linings. Comparison of the fibre proportions in brake lining material and brake drum or air-horns dust [Table 4) shows that in the latter. the percentage of fibres is greatly reduced. The analyses of the brake drum dust samples confirm a very low ashestos content. These findings sug?set that luring usage. the materiel undergoes changes in physical and/hr chemical form. Enquiries from research workers in UK and USA indicate that this is a finding which has been observed elsewhere. and current thought is that during braking. high point contact temperatures are reached., is a result, thermal decomposition of asbestos takes place. producing an amorphous, non-fibrous magnesium silicate. Under Vary extreme operating conditions. the binder nay decompose and release part or the asbestos ae iree iibre. but such circumstances would be most unusual. Conclusions On the environmental and analytical evidence obtained. it does not appear that a significant hazard to health should Passenger Car Repair Shop. It would be helpful, howevsr. for I- clinical PROPERTY OF FORD MOTOR PRODUCEDBYFORD FAFDOO10816 PRODUCED BY FORD FAFDUGUUIUBIB clinical examinations to be made of some repair mecnanioa ii i with long experience of brake cleaning to confirm this View. 1% it would also be desirable to include in Service 1 manuals. a general instruction that inhalation of dust during brake cleaning chould be minimised. and it practical alternative methods. which would produce less duet; can be devised. their use should be recommended. The present investigation has been confined to servicing of passenger cars, and a further etudy of heavy vehicle aervicing is under considerationto:- can-Frac- I 3-: If I I. ll. inane: . 811226 PQOPEHTY 0F FORD MOTOR EGHPAHY PRODUCEDBYFORD FAFD0010817 PRODUCED BY FORD Table 1. Details of air aum?ling Durniiux Activity Type Location mina. during [approx] 5min puma Do: A A1 ta] sum. by on so 1 Comm 1 ?2 lb] Duat cloud. than static 30 1 Cortina A3 45 1 Corsair A4 In] Static, by car 45 1 Corsair 55 Dost cloud. than static as 1 Corsair A6 to] Static. by car 30 1 Corsair no: T.P. st ?1 45 ll Cortino Cor?inn not T.P. 35 BE LL St?tic- by 35 1 Now Cortinu 3? 35 ?a LL (bl Dust cloud. than atntic 35 I New Cortinn Bax C1 M. Personal samplo 60 1 Corsair C2 56 ?1 Corsair 1 Zodiac 03 59 None C4 56 1 Cortinn 2 Corsair: 05 60 1 Cortinn tl Prefect lpart) CG 64 1 Protect Icontd.l I c7 70 Cortinaa 1 Corsair T.P. Thermal Proci itaior . 611227 OPERTY OF ROTOR FAFDOO1OB18 PRODUCED BY FORD Table 2. Results of Thermal Procipitator Samglea PRODUCED BY FORD Sample Duat concentration s??pla Sample details time Particles/ac Fihrnajuc mine. la}8ta11c - Time-weighted avoraga 103 '1.Time?weighted averaga 1 15 o. 23 [hi 1n dust aloud T?on afaiic Time-waighted average I 196 1.181 0.2 Time-woightad average 137 0.37 Bi1228 OF :020 MOTOR :oupnuv PRODUCED BY FORD FAFDOO1 081 9 Table 3. Results at Hemhrune Filter Counts Sampla Sample Datnila tins Fibres/co. mina. 1. ntmoaghara 555219: In] Static by car 32 45 1.12 86 35 1.12 Tima?weightad avorago 1.25 lb) In dust ulnnd. than static 84 45 1.71 3 BB 35 3.62 Time-weighted average 2.55 11. Personal samples 01 60 0.63 .m CS 59 0.21 0% - 56 0.96 65 Sample lost 86 64 0.38 10 0.19 Timanweightad nVorngo 0.68 911223 PHOPEPTY 0F FORD HOTOP. COHPARY PRODUCED BY roan FAFD0010820 PHGDUCED BY FORD 0111620 Table 4. Fibres - as parcentcio or totol portioloa oLoorTo mre proportion - 5 sample Incineratod Brake lining motoricl 28 12.3 Brake drum dust 0.6 1.6 Air-horns dust - 1.3 Table 5. of Broke drum dost Eioctron x-roy X-roy Sam 1. diffraction diffraction diffraction microscopy (normal (extracted ageclmanl specimen] 1.Anglin Von Chryaotila Iron quartz Lesa than 5! present yrcaent. No ohryaotile. chryootile possibly 0.1? doloctod. to 15. 2.00rtino Mull Loss than spacincn 1. a.Ang11c cor A5 specimen 1. B11238 PacPEntv OF roan ROTOR cournuv "av'?ro?nd 1? FAFD0010821 PRODUCED BY FDRD Phi-1100001082!