Document zo34vE260vZVV5Np486xYwVQg

FILE NAME: Z/ZZZZ/ DATE: & DOC#: / DOCUMENT DESCRIPTION:>Z/Z^,ZZ/Z ,WZZZ  . PWNnFF'S EXHIBIT I ~o Mr. J. Marsh. Mr. R.H. Mereness, 1Xecut1ve Director, ; Aabeatoa Information A.asoc1at1on/NA, : l66o L Street N.W., . Waahington D.C.200.:,6, U.S.A. 26th Pebruar-J, 1975. SHa/CML' Cop,y1 JJV114. Dear Bob, Insulation Hygiene Progress Report - Volume 6 No. l 'lbank you tor sending me a copy ot the above report, which I have read with considerable interest. 1!le b.lrden ot the argument seems to be that dust measurement.a showing a low average level may be deceptive in insulation workers where exposure 1.s 1nter:n1ttent and ir.ay include high peaka of short duration. Al5 1t is believed. that d.iseaae may be associated With these high peak.!S the validity ot a standard such as the 2 t'ibre/ml U.K. standard, is called into question. Por some considerable time now, I have talked about the a1gn1f'1cance ot high peak exposures and recommended that aateguards to cover such situations should be built-in to atandards. In my evidence at the PUblic Hearing 1n Washington 1n March 1972, I included the following statement on the U.K. StandardI - zt was realised trom the beginning that the at.andard had certain limitations. 'Ihe information an which it was based was scanty and was drawn from a textile plant, where dust concentrationa did not fluctuate widely. 'Ihat it might be unwise to apply 1 t to situatioru, experiencing high peab or concentration was recognised and it was recomnended that the time concentration conce t should not be uaed. above 10 fibres c. , because too little was known about the effects of high concentrat.iona tor short periods ot time, which might 1ntertere with the normal l'LID8 clearance mechanisms." Cant 'd AaDeSt.OS 1ruo~uon A:SBOC1.A"W.O[1/' W\1 Wuhington. Again 1n my tinal recommendation I said the tollowingi- "It i,s rrry view that a sizeable part ot the health problem racing the asbestoa indwstry tody 1a due to the effect ot peaks ot very high d.wst concentration, albeit only for short periods, attending uncontrolled ""Perations, such aa are encountered in the insulation industry. A standard which removes the worker from the ettect ot auch peaks is probably more important than one which imposes l.ll'lreasonably strict average levels." I returned to the same argument 1n my paper ent1Ued "Erivironmental Data 1n Industry" at the Lyon Conference 1n October 1972 where I said: - "It is well lalQwn that the threshold limit value of 2 t1bres/ml was calculated f:-om the OOHS chrysot1le atandard, assuming an occupational exposure ot 50 7ea.rs. While this may be desirable for persons working full-time with as bes to~.., it is probably too tight a standard for many asbestos users who handle the material only intermittently. 'Ihe possible ettects of L~termittent high du.st concentrations have already been referred to; it is therefore recommended ,. tha14whatever threshold limit value (TI.V) 1.s stipulated. (based on the average concentration over, aey, ii hours) exposure of the worker to peaks higher than five times the TLV (measured over 10 minutes) ahould be avoided.~ 'lhe Factory Inspectorate 1n the U.K. 1n operating the 1969 Asbeistos Regulations have .shown that they are aware of the aituation by saying that while the TLV based on a 4 hour aample shall be 2 fibres/ml,levels above 12 fibres/ml. based on a 10 minute sa:nole are not permitted. If the situation cannot be improved IT.I tighter d~t control. then the workers mu.st wear respiratory protection. 'Dus is obviously d.irected at the insulation industry and its effect 1s to prevent the worker being exposed to these high peaks of concentration. SUrely this is better than pitching the average level very low indeed to take into account the possible high peakzs which might occur. I hope these corrments will be or help to you end I am sending a oopy ot th1.s letter to John Marsh. With kind regards, Yours sincerely, s.~ /