Document 6byK73y4LgOmr9MG5mxpeEoo

E D .V, A N W\ I in' E S LIMITED TIMMINS, ONTAflIO. CANAOA M/ ali?nic December 29, 1972 y.r. Harr:* fotppard, Vice President Gtrl .'till Products Division Foseco Incerr-Tsted P.0, Tic:; $725 CliJYiLAMD, Ohio U135, U.S.A. Dear Ilr. Shcururi: Further to our telephone discussion of yesterday we are pleased to confirm that over 99. ?o* of the particles in Kedman Cationic Fibre are these with which the CSIIA asbestos reflations are not concerned. In view of the Fact that the amount oF HCr to be ccccd to ycur product is quite low the total percentage oF asbestos Fiores above Five microns (C.Olfi) will be Further reduced depending on the e:cact percentage of KCF in your product. The composition oF Hedmr.n Cationic Fibre and its position concerning Occupational Safety and Health regulations cay be best described by giving dear official teztbcch definitions oF the terms "asbestos", "chrysotile", "serpentine" and "magnesium silicates", and by relating Hedman Cationic Fibre to those terms, ".-.rbessos1*: A general term embracing the Fibrous varieties oF ninerals. There are st-veral rinis of asbestos, of which the most common arej Chrysctile (H^rlgjiigCq), Crcciuclite ('.UStiSLCjzTeZiCy), Trs.tolite (CaMg55i8022(C*02, *ctinolite (C*.(::g?e)3 (DiCj)^), Anthcchylite and Amosite (HgFe) Si03 Apart from being non-flammable, the characteristic all asbestos minerals have in co.f.on is a Fibrous structure; they diFfer widely in chemical composition and physical properties. Medical authorities and British government occupational health regulation sake a clear distinction between various asbestos minerals also as to their relative safety (see below), "Chr-.-sctile"; The Fibrous Fora of the serpentine mineral, Kofc as harsh or brittle as otner csucstcs, chrysotile is recommended by the British government as a safer substitute For South African eroeidelite-asbestos, British occupational safety regulations ere 10 times as stringent with crocidolite than with chrysotile, "Sorrcr.tine"; A mineral (rock) which cheelrally belongs to the magnesium silicates. (Dcrpsr.tine is a geological name, magnesium silicate a chemical term which applies also to several other minerals.) only the variety of serpentine which is fibrous in structure is chrysotile asbestos. The platy fora is either antigorite or lirardite. Lizarditc is also lath-like in structure. Being non-fibroue neither antigorite nor Htardite arc asbestos, 'y.-.mcgjum Filicstes": Chemical term of compounds of magnesium oodde and silica, Mary minerals, such as olivine, serpentine,, talc, soue clays, soap stone etc. are magnesium silicates. "Hrd-mr Cationic Fibre": A natural mixture of magnesium silicate particles produced by a special process From a unique serpentine host mineral, Electron micrograph rQ3-"aaaaaa3*43 ,:r. Harry Sheppard December 29, 1972 studies r.t 17,6COX (lower rngnification is leas accurate) indicate that only O.Cif of the particles in liCr are cliry.*oiilc fibres above 5 microns. This is arrived at as a result of there being ? to 20;i chrysotile fibres in the product, C.2Z of which are estimated to be above 5 microns (see report) (2CS of 0.21 " O.CiS), The balance was determined to be mainly prismatic laths of lizartiitc 0,2 to 1,0 microns in length and non-fibrous, therefore non-asbestos. Due to the prcdc.tinanee of non-fibrous and there fore non-asbestos particlea in 15CF it should not be confused with the asbestos grades on the market. (as a similar example we may cite talcs, which are magnesium silicates, basically non-fibrous but with a content of trenolite csbestos). CSHA * ' - The CSHA regulations Governing the exposure to air-borne asbestos dust concentrations are based on medical research, originally carried out in Britain where a higher than average rate of lung diseases was found ar.cng workers who smoked and were exposed to uncontrolled concentrations of asbestos dust, oainly crocidolite. Suspected as a possible health hazard were asbestos fibres longer than 5 microns. CSKA asbestos regu lations, which Unit the peraissable concentrations of air-bome fibres longer than 5 microns to 5 fibres per milliliter (to be reduced to 2 fibres in 1976), are not concerned with fibres of 5 micrcns or-shorter, or non-fibrous particles. Based cn the foregoing and on practical experience in our own operations and at our customers' .plants, it is reasonable to expect that it should be much easier to comply with CSM>/fwinJaVis using Hedmxn Cationic Fibre than with the asbestos fillers tested, under identical conditions, Membrane Filter Tests provide conclusive data at each location. Should you require anything further please give us a call. Yours sincerely. J.J. Mangan/rb encl. Sources of Information The liew Jersey Zinc Company Research Department, Palmcrton, Pa, < Dana's Manual of Mineralogy (Revised by C.S. Kurlbui, Jr. Ph.D, Harvard University) Industrial Minerals and Rocks - published by the American Institute of Mining and Metallurgical Ingi r.c-eba. * Occupational Health bulletin, 1971, Vol. 26 * Department of ilaoloyment, Britain, "Health a Safety at fork" * U.S. Department of Labour, 03mA, "Standard for Exposure to Asbestos Dust" SS1910.93a * HygiriiO Standards for Cnrysotile Asbestos Dust by britisn Occupational Hygiene Society Page 8