Document DMqdXo3vjYK2oYY44bgOwwm0N

362/tn/BFUC The Society of Automotive Engineers, 2 Pennsylvania Plaza, Hew York, K.Y.10001, U.S.A. Inc., -London, WC2B 4JY 8th December, 1971* Dear Sira, We have been asked by our members in the British friction materials industry in the U.K. to put their views to you on the proposed Illinois State Regulations concerning asbestos and asbestos products. We enclose herewith their comments on the friction material aspect of these draft Regulations. We have no doubt that the American lining manufacturers will be making strong representations to the Illinois authorities for amendments to the proposals and we shall be grateful if you could make our views known as set out in this enclosure. Yours faithfully. Secretaries Enc. FMSI--0106 FMSI 02865 PiiOPOSVD ILLINOIS JTAT25 BAN ON oU^US LIMITS The British friction materials Industry views with deep concern the proposed ban on the use of asbestos in brake linings by the State of Illinois. It is not aware of any medical evidence that could possibly justify such legislation. On the contrary it would have the effect of withdrawing from the market products that were used to promote road safety, without producing any significant improvement in the levels of urban atmospheric pollution. It would expect any of the known alternatives to asbestos to produce general particulate pollution of a measurable amount. 1. Whatever materials are used for brake linings the current state of the art ic such that the action of braking will generate products of wear. The asbestos content of conventional brake linings is almost entirely converted by the action of braking into forsterite or other amorphous, inert material* which are no longer asbestos. On the other hand, if non asbestos alternatives are used (e.g. iron powder, sintered metal, ceramics, steel wool etc.,) the resulting wear products will be released unchanged. 2. Measurements have been made of the amount of free asbestos fibre left in brake lining dust. It is an insignificant proportion of what is in any case a minute amount of total dust. The amount of free asbestos fibre that has been found in brake lining dust from vehicles, is about 1# of the total products of wear. (l). Indeed estimates vary down to 10"9g/g, i.e. for each gramme of wear products only 10-9 grammes of free asbestos may nay remain. 3. We assume that the risk of contracting mesothelioma is the principal cause of environmental concern - there is clearly no possibility whatever as a result of vehicle braking, of a community risk of asbestosis or lung cancer, which are solely occupational risks. For technical reasons only chrysotile asbestos is used in the manufacture of brake linings and disc brake pads. This is not the type of asbestos with which mesothelioma has been mainly associated. 4. Measurements of chrysotile asbestos in the ambient air in an industrial centre in the United Kingdom have shown that the level must be less than 10"*? g/m^ because of the limitations of the method used. This means that they must be a thousand times lower than the British Government acceptable level for occupational exposure. Current investigations using a more sensitive method indicate levels of 10"^ to 10"10 g/ra^, i.e. 2 or 3 orders lower still. (2). Brake lining wear cannot therefore be a serious source of atmospheric pollution. 5* In one of the largest brake testing laboratories in the world, housing many dynamometers engaged 24 hours a day in wearing away friction materials, the average monthly asbestos count is 0.2 fibres /cc, a tenth of the British Government's occupational standard. Footnotes 1. Hiekish D.K. and Knight K.L. (1970) Annals of Occupational Hygiene Vol.13* No.1, page 20, 2W | j letter to Nature attached. ' British Friction Materials Council 26th November, 1971. \. . FMSI 02866 MUftf VGl 13<t NOVEMBER 12 1971 93 Cbrysotile Asbestos in urban Air THr industrial use of chrysolite asbestos is increasing and ilio question of whether its concentration in urban air constitutes a hazard has been raised. But rr.easurctnems of asbestos in air near asbestos factories have prosed negative with present analytical methods, so under the sponsorship of the Asbeslosis Research Council see are developing a more sensitive technique. This article is a preliminary account of the estimation of chrysolite near a large, asbestos textile factory at Rochdale, Lancashire. There arc several uncertainties in the technique, so sve were, expecting to obtain only an order of magnitude estimate. Nevertheless this would have been an important figure to have because of the lack of data on the amount of asbestos in air. As it happened, sve were only able to determine an upper limit for the chrysolite concentration svhich turned oul to be three orders of magnitude lower than the threshold value for occupational exposure set by asbestos regulations. Obviously even more sensitive techniques are required and arc now being developed. Wc used an X-ray diffraction technique based on the measure ment of the integrated area under the (002) peak of chrysotilc. The equipment, which consisted of a Phillips 1010 generator, a vertical goniometer with a step scanning attachment, and a proportional counter with pulse height discrimination, could be reliably calibrated down to 10 pg of chrysolite compared with (he I to 10 mg range reported by Cruble', and was cross checked by estimating the magnesium content of the calibration samples by atomic absorption spectroscopy. Sampling involved the collection of airborne solids from 1,000 mJ 110" I.) of air by an electrostatic device (H. Litton Systems Inc.) in which up to 10,000 I. min'1 are drawn through a 20 kV corona discharge. Particles in the air are electrostatically precipitated onto a plate and concentrated into ~ 100 ml. of liquid. The collection efficiency depends on the siae distribution of the particles and the sampling rate, but the size distribution or chrysolite in the atmosphere is not known. Therefore wc estimated the colteciion efficiency indirccily by running the sampler in pari of the asbestos factory where a low concentra tion of asbestos is known to occur (Fig, 1) and we found the collection efficiency to be almost 100% when the air is sampled at about 2,000 I. min-', dropping to between 25 and 50% at the rale of 10.000 1, miti 1, depending on the actual size dis tribution present. As we were aiming at only ah order of ntugni- FMSI 02867 94. NATURE VOL. 234 NOVEMBER \2 1971 Tabi 1 V. O.Jthrr Cun<J'i>on. Uunnu Sampling Date (1970) Situ Wind Weather April 22 April 24 April 27 April 29 May 6 May U May 28 May 28 May 30 May 30 June 3 June 10 June 10 October 23 October 23 October 23 October 28 October 28' October 28 1 1 1 1 1 1 3 3 4 4 2 2 2 1 1 1 i 1 1 SW moderate SW slight Nl; moderate SW moderate S strong N fresh W light W tight W light W light SW light SW slight SW slight W moderate W moderate W moderate N light N light N light ItruLcn cloud Gfouivd hare Ground ha/e Ground h.i/e Ground hare Ground haze Overcast, dull Overcast, dull Overcast, dull Overcast, dull Overcast Ueat haze Heat haze Broken cloud Broken cloud Broken cloud Broken cloud Broken cloud Broken cloud tilde assessment of asbestos in urban air, we were prepared to accept this uncertainty in the collection efficiency. The map (Fig. 2) and Table 1 show the location of the sampl* mg sites and the conditions in which the samples were obtained. The factory is in a hollow, and sampling site No. 2 is at the tame height as the roof of the filter nailery, which is the chief air o t from the factory. Sampling site No. 1 is about 30 fool higher than site No. 2. Sites 3 and 4 were in the gardens of houses, site 3 being about 3 km upwind of the factory and site 4 being about 300 in downwind. AU thediffraction traces (for example, Fig- 3)contained strong lines of kaolinite and quartz, probably from the local soil, which made the assessment of chrysolite difficult because the broad (001) line of kaotiniic (7.18 A) is close to the major (002) line of chrysotile (7.36 A). Fortunately chrysolite is easily decom posed by boiling in 1 N hydrochloric acid whereas kaolinite is unaffected, so it should be possible to measure the amount of chrysotile present by subjecting the samples to acid leaching and measuring the corresponding reduction of the intensity of (he composite X-ray band. The fact that this process led to no reductions in band intensity for any of the samples indicated that the amount of chrysotile present was below our detection limit. We ought to have been able to detect IQ of chrysotile by itself, but clearly the presence of kaolinite may have reduced the sensitivity. But the addition of 100 ps of chrysotile to our collected samples could easily be detected, so we can say that our samples collected from 1,000 m' of air contained less than 100 jig of chrysolite--in other words, there was less than 0.1 tig ofchrysolite per nr* of air. The threshold limit for occupational exposure set by the 1969 Asbestos Regulations2 is 0.1 mg m. quartz quartz 2$ (CuK) Fig. 3 X-ray diffraction pattern from a typical dust sample near the Rochdale factory. Fig. 2 Wan of T.U.A. factory, Rochdale. The sampling sites arc indicated by the arrows 1 and 2. A. Position of the chief filler gallery exhausts. A more sensitive method for estimating chrysotile is required, and we are developing a technique based on electron micro scopy. Preliminary examinations under (he electron micro scope of samples collected by the Litton sampler indicate that the actual chrysolite level may be a further three orders of magnitude below the X-ray detection limit (that is, about 0.1 ng). . The samples have so far been collected in the close vicinity of the Rochdale factory. It is now proposed to sample air at certain representative urban and rural locations in UK and estimate their chrysotile content. A. L. Rickards . D. V. Baoami Turner Brothers Asbestos Co. Lid, TO Box 40, Rochdale, Lancashire Received April 18; revised September 22,1971. ' Crabk, J. V., Amcr. /f. live. Assoc. J., J7. 293 (19M). s SiamJo'd%jor Asiteuos Dnu ConrmtraoctJar (hi* * ith the Asbestos Regulations Technical Lata Sate li (l !M Factory Inspec torate, hte9>. FMSI 02868