Document oODqRVqXonzZ64rqQGKpYkow

FILE NAME Cape Asbestos CAPE DATE 1973 Dec 18 DOC CAPE006 DOCUMENT DESCRIPTION Memo - Hazards of Heath Associated with Crocidolite and Amosite Asbestos with Cover Letter from North American Asbestos Corp NAACCORT NAACCORT NAACCORT NORTH AMERICAN ASBESTOS CORPORATION 150 NORTH WACKER DRIVE CHICAGO ILLINOIS 60606 PHONE 312 726-8515 CABLES NORAMCO CHICAGO December 18 1973 : Mr. R. H. Mereness Asbestos Information Association 1660 L Street N..W Washington C. 20036 J. 1. PLAINTIFF'S 259 ra ettey at. LS} a er YO . er ATS EVO abe 0G Dear Bob During my recent visit to your offices you will recall our discussion taining to a position paper which Cape Asbestos asked permission to submit to the ALA We are enclosing copies of the document as received today per- We believe there have been tendencies in some areas to segregate Blue and Amosite asbestos into a separate category as opposed to Chrysotile when related to health hazards From this point of view it would appear that Cape has endeavored to fairly and fully present all the known facts as regards Blue and Amosite asbestos These documents are for your files and information and may be circulated to all members of the AIA should you so desire In the event you believe they would serve a useful purpose copies may be distributed to selected people in OSHA If you have any questions relative to this matter please contact me Sincerely yours NORTH AMERICAN ASBESTOS CORPORATION CGMorgan encl oo vo / ~a ) e --,-- _ _ fee Vice President Manager ~ oe oe en TEEN eg mene Ft agp yn oy nn ** ** a a ee 1 2 2.1 Memorandum from The Hazards Cape Asbestos Company to Health Associated Limited with Crocidolite and Amosite Asbestos on Seaeceoanananeane ammea Oe eT INTRODUCTION It is not infrequently exist with crocidolite not so pronounced with suggested that special hazards may blue and amosite asbestos that are chrysotile As the largest producer and processer of amphibole asbestos Cape is naturally concerned about this and while being fully aware of its responsibility as a supplier of these materials it is anxious that the facts relating to these forms of asbestos should be fully understood It is unfortunately true that through an insufficient understanding of the hazards involved workpeople in the past have suffered damage to their health through exposure to inadequately controlled concentrations of asbestos dust of all types It is inevitable with problems of this kind that evidence relating incidence of disease to the type and intensity of exposure must largely be based upon the best assessment it is possible to make of what has happened in the past With asbestos exposure this is particularly difficult since long periods of elapsed time are involved Great efforts have been made to sift out the facts and with amphibole asbestos these are very fragmentary It is suggested that the evidence particularly connecting mesothelioma with exposure to crocidolities quite insufficient to justify the definite conclusion that is sometimes drawn The evidence available certainly suggests that it is the particular uses to which crocidolite and amosite have been put in the past in consequence of their individual properties that has resulted in their special mention in the general health area rather than any exceptional biological hazard that may differentiate them from other types of asbestos The background for these conclusions is set out in this memorandum CROCIDOLITE BLUE ASBESTOS Chemistry and Mineralogy Crocidolite asbestos contains about 50 of combined silica Rearly 40 of combined ferrous and ferric iron as oxides Tables I and II compare the physical and chemical properties of both amphiboles with chrysotile asbestos and chemical composition of these asbestos minerals and the In addition to possessing the high bulking and structural characteristics of amosite crocidolite is the strongest of asbestos fibres and has a high resistance to acids It has been used extensively in place of chrysotile asbestos in textiles insulation mattresses packings and as a filler when resistance to acids is important It was also used in spray insulation on account of its high bulk volume Today however its use is predominantly in asbestos cement pressure pipes acting both as a filter aid to speed production and as a reinforcement in the final structure 12 Df JHM 01026 1 eRe ROO Oem ee nee OO +e -2- 2.2 2.2.1 2.2.2 2.3 2.3.1 2.3.2 Possible Association between Crocidolite and Mesothelioma For some time there has been a belief though not universally accepted that there are greater risks to health from crocidolite than from other types of asbestos especially chrysotile This view predominated in the U.K. during the period when the U.K. Asbestos Regulations were being formulated and led to the inclusion of discriminatory provisions regarding the use of crocidolite When the subsequent interpretive document establishing working guides for safe levels of exposure was prepared this also included a separate standard for crocidolite based it was admitted on an entirely arbitrary assumption that 10th of the normal standard would ensure ample protection At that time the results of Harries detailed and thorough investigations were not available and as far as the U.K. was concerned the principal and limited of crocidolite asbestos had been in the form of mattresses insulation little used thermal insulation and especially sprayed For mainly technical reasons crocidolite was in the U.K. for C pressure pipe manufacture The report of the Advisory Committee on Asbestos Cancers to the Director of the International Agency for Cancer Research Lyon 1972 said The risk of mesothelioma is greatest with crocidolite less with amosite and apparently less with chrysotile It also states that there is evidence that all commercial types of asbestos except anthophyllite may be responsible The evidence upon which these beliefs are based rests heavily on the study in South Africa reported by Wagner in 1960 The results of further studies associating crocidolite with mesothelioma particularly in manufacturing situations are less specific but all of the significant evidence is reviewed below Mesothelioma in Association with Crocidolite Mines Wagner 1960 6 investigated an unusual frequency of the rare tumour mesothelioma in the Cape Province of South Africa Of 33 cases 8 had evidence of asbestosis but of the remaining 25 24 had a probable exposure to crocidolite mostly through residence from birth or early age in the vicinity of crocidolite mines in N.W. Cape Subsequent studies enlarged this study to 120 cases 110 of which were said to have been exposed to crocidolite more than half through living in the vicinity of mines and mills Wagner's is the only epidemiological study where there is no other type of asbestos than crocidolite known to be present The conditions prevailing during the exposure period of his series of which he says the average latent interval was 40 years were extremely dusty - in a dry and arid region The exposure level and the duration of exposure for the great majority of those living in the immediate neighbourhood playing and freely moving about the tailing dumps and stockpile areas would have been considerable in those days Hand cobbing freeing fibres from the rock capping was done by female labour accompanied by their children Mt tt, th LEE eo. 13 010271 010271 -3- 2.3.3 Subsequent surveys Cremer 33 Webster Lyon 1972 34 and investigations by the South African Bureau of Mines have not produced evidence of a growth of cases corresponding to growth in production anticipated by Wagner 360 cases have been reported 155 with no known exposure 117 with definite industrial or environment exposure They have also indicated that where there has been a positive exposure to asbestos in mining the majority of cases 83 out of 88 reported since 1956 appear to be confined to the south and central part of the N.W. Cape crocidolite mining areas 2.3.4 In Canada a research team led by Doctors Corbett and Alison McDonald started in 1967 a study of the health of workers in the Quebec asbestos mines and mills with the primary purpose of assessing what risk of lung cancer there might be in persons exposed to Canadian chrysotile asbestos Reports covering various aspects of the survey have been and will continue to be published but a progress report issued by Dr. Corbett McDonald in 1970 18 conveys an impression which does not seem to have been changed materially by subsequent reports The study of some 12,000 employees in the Quebec mines and mills born between 1890 and 1920 showed a death rate for lung cancer among those in the highest category of dust exposure three times greater than that of employees with minimal exposure had little The employees in the lowest dust categories apparently or no increased mortality from asbestos disease . As far as mesothelioma is concerned few cases were found 13 Only 165 cases were recorded by pathologists in the entire country during the period 1960 - 1968 and only in a minority of these was there a definite history of having worked with asbestos 11 definite 9 probable Ten of these including 3 engaged in mining or milling would apparently have only been exposed to chrysotilo asbestos 10 were involved with insulation materials and so may have been exposed to other types of asbestos 2.3.5 2.3.6 In comparing McDonald's surveys in the Quebec mining area with Wagner's findings in South Africa it must be remembered that climatic and working conditions were entirely different Comparison is further confused by the difficulty of retrospective case finding and diagnosis together with uncertainty of exposure history in such widely differing locations Considerable efforts have been made to confirm more positively the association between crocidolite exposure and mesothelioma in the N.W. Cape The results have been inconclusive An extensive survey conducted by the Pneumoconiosis Research Unit throughout the N.W. Cape in and after further extensive 1961/62 did not reveal research Professor I. new cases Webster 35 has recently suggested that crocidolite must be associated with another factor before malignant change occurs There continues to be difficulty in establishing conclusive evidence in this area As an example of this experience at the crocidclite mine of Cape Asbestos at Koegas may be quoted This is probably the oldest commercially significant mine having been worked for 80 years and with many long serving employces checks are As with all South African mines regular health compulsory but at the time of writing no cases of mesothelioma have been notified to us as from former employees and we are not aware of any 01628 01628 01628 01628 01628 14 RETO ROR OO ITI -4- 2.4 2.4.1 2.4.2 2.4.3 2.4.4 2.4.5 2.4.6 Mesothelioma in Asbestos Manufacturing Newhouse in 1964 3 a connection between undertook the first attempt to investigate crocidolite and mesothelioma in a manufacturing situation She looked for a possible connection with exposure to crocidolite asbestos among mesothelioma cases recorded by a hospital in East London Of 76 cases she established that 23 had worked in asbestos factories 7 had worked in the application of thermal insulation 10 had probable exposure of an indirect nature 11 others lived within -mile of a large asbestos factory The remaining 25 had no traceable connection with asbestos While the positive or probable it was believed that exposure was in all cases to asbestos crocidolite of all types could have been present Subsequent studies 1968 9 1972 29 1973 30 all related to similar industrial exposure The further study by Newhouse 1972 29 of a group of 716 women employed between 1936 and 1942 revealed 11 mesothelial tumours over 40 of those in the cohort had worked in textile processing departments and 10 in mattress making and chrysotile were largely used in the former and Crocidolite amosite in addition to these in mattress making In another survey 30 of over 4,500 male workers in an asbestos factory making textiles insulation products of various kinds jointings and brake linings Dr. Newhouse reported that there was no excess mortality among those who worked in jobs where exposure was low or moderate though where work entailed heavy exposure there was a significant excess from cancer of lung and pleura in some cases where total period of employment had been less than two years Occupations in these categories included insulation manufacture textiles fibre opening and disintegrating mattress making asbestos store and dust and waste collection Dr. Newhouse's work as a whole represents a very thorough study of the effect upon workpeople and those living in the vicinity of conditions in an asbestos factory where it is now realised there was insufficient control of asbestos dust in earlier years and particularly for a period during and immediately followitnhge last war this factory - frequently All types of asbestos were on the same machines - and used in it is certainly not possible to pinpoint specific types of asbestos dust to which particular workers were exposed For this reason Dr. Newhouse's work cannot be used as a means of assessing relative hazards of different kinds of asbestos Dr. Gilson 31 refers to nine cases of mesothelioma in a group of workers employed in the assembly of crocidolite asbestos filter pads in gas masks during the war Information concerning the asbestos content of these filters is now imprecise but the nature appreciable and possible of the process was such as to generate heavy dust clouds in the immediate breathing zone of the operatives information from Dr. Lewinschn that Dr. Gilson a group of also quotes mesotheliomas were discovered among men working in a 20's where possible heavy exposure factory in the to crocidolite occurred Crocidolite has been used for at least fifty years throughout the world in the manufacture of asbestos cement which accounts for the largest use of asbestos but two possible cases only have been reported from this sector of industry Another use has been as reinforcement in plastics c.g. battery boxes No cases of mesothelioma are known to have occurred in this connection 5 CR ene a oe rg ren te ee ane I eee nee me, on . 01029 01029 01029 -5- 2.5 Mesothelioma in Naval Dockyards and other Shipyards Harries 7 22 studies of pleural mesotheliomas among workers in UK naval dockyards indicated exposure to all types of asbestos _ Heaviest concentrations recorded were in stripping sprayed asbestos normally crocidolite which up to that time had been used in very large quantities for insulation in naval vessels 2.6 2.6.1 2.6.2 This was possibly the exposures to asbestos first study to recognise the very dust that occurred when asbestos severe insulation was stripped within confined spaces on ships Dust levels exceeding 1,000 fibres were recorded at some points Subsequent work has confirmed this and the relationship between incidence of mesothelioma in the country U.K. as a whole and areas where shipbuilding and ship repair work has been carried out has been illustrated on a map by Wagner 36 Comments on the Evidence Concerning Crocidolite The only evidence based upon exposure to crocidolite alone is that supplied in Wagner's papi Subsequent work has not confirmed the conclusions that were at one time drawn from Wagner's findings : Other exposures that are quoted in this connection have been both mixed and heavy No conclusions regarding the specific contribution of a particular type of asbestos can therefore be drawn 2.6.3 There is no evidence of mesothelioma in association with the use of crocidolite where the form of product or naturoef use has not minimal resulteidn excessive exposure is necessary dust The idea that only to produce mesothelioma has developed by suspicion and there are no facts to substantiate this idea 2.6.4 A detailed study of cases of mesothelioma associated with exposure to asbestos throughout the world excluding mining see Appendix A which prompts the above reservations indicates that of 763 reported cases 664 are said to be definitely associated with occupational exposure Most of these studies are of course of groups of workers in occupations where an exposure to asbestos dust is expected This obviously weights the sample heavily Of these 290 are positively stated to have occurred where chrysotile and crocidolite and amosite has been in use in 361 cases no details of the type of asbestos are given but it is apparent from the general references to the type of exposure that more than one type was likely to have been present Further scrutiny of the occupations recorded in these studies also indicates that of those listed as occupationally exposed directly or indirectly 553 were engaged in or in close association with insulation work either on land installations or ship repair and construction The remaining cases were also associated with manufacturing processes such as textile manufacture mattress making and other insulation manufacture where dust concentrations were known to have been heavy tae a an oemw de anT nI yE. : 030 16 06- AMOSITE 3.1 3.1.2 3.1.3 3.2 General As indicated in Table I ampsite asbestos also contains approximately 50 silica Its characteristic is the with about 40 springiness of of ferrous the fibres oxide and the high bulk volume highly resistant produced when to corrosion processed It is also These characteristics made amosite fibre the preferred material for heat insulation applications and consequently the most frequently used by insulation workers The preference for amosite thermal insulation material spread to most industrial countries and such materials were used in greatly increased quantities from the 1940's to the late 1950's Chrysotile asbestos was also used in this field as the reinforcing fibre in calcium silicate section and 85 magnesia Amosite has come under particular scrutiny in because of its extensive use as an insulating and after the war years the United States material during Amosite has not been associated with mesothelioma to the extent that has crocidolite and this probably results from the almost complete absence of any history of mesothelioma in the Northern Transvaal the only area in which amosite is mined The question to be decided is whether exposure to amosite involves a greater hazard than exposure to chrysotile so far as asbestosis and lung cancer are concerned Amosite and Insulation Workers 3.2.1 The extensive investigations of Dr. Selikoff and his workers are well known and no attempt is made to summarise these in this memorandum The important point for present consideration is that the workers upon whose history the investigations are based were involved in the thermal insulation industry There are two sectors of this the first being concerned with manufacture of products and the second being concerned with the fitting and stripping of insulation on site - 3.2.2 For a period during number of factories and immediately after the last war a in the United States and Europe were involved in the manufacture of preformed insulating blocks pipe sections and mattresses In the United States these materials were largely based either upon chrysotile asbestos in the form of 85 magnesia containing 15 of asbestos or upon amosite in the form of Unibestos containing 80 - 100 of asbestos It is now clear that conditions in many of these factories were very bad by today's standards The products were in great demand during the war particularly by the U.S. navy Hours were long and safety standards were relaxed in the interests of obtaining vital materials in time of war Dust concentrations ware undoubtedly heavy andand the health of many workpeople has suffered in consequence of this sector of the industry concerned with the fitting and stripping of insulation either in the form of moulded pieces or as sprayed fibre In the United Kingdom such work was not subject U.K. Asbestos Industry Regulations 1931 and and control by the dust measurement Harries 1968 7 showed that insulation containing only 15 even with asbestos calcium silicate totg ogetherether with asbestos 17 a ee ae ST - ee ee eDeegeesEREE Ang oe -7- 3.2.4 4 4.1 rope cloth and plastic mixes mean concentrations in the general atmosphere in boiler rooms where lagging was taking place were 22.4 fibres Some individual operations concerned with fitting insulation give average breathing zone samples as 256 fibres none was less than 43.1 In operations particularly associated Harries quotes mean concentrations of with over crocidolite 300 fibres at the two place of or three work decks while in adjacent areas and passageways away from the work site mean concentrations in excess of 30 fibres and as much as 177 fibres were recorded It is clear that men in occupations in no way connected with the asbestos work and whose occupation would be assumed normally not to expose them to asbestos dust would have been exposed to concentrations which would be considered very heavy in an asbestos factory Such concentrations are also likely to apply to such occurrences of asbestos related disease in areas of shipyard repair and construction reported by McEwan 19 Stumphius 11 Bohlig 21 and others Selikoff has suggested 28 that average dust concentrations to which American insulation engineers had been exposed would have been low He bases this on some measurements of various operations 0.3 to 8.4 commonly performed by these men quoting levels from fibres He refers to similar results in another survey with higher levels noted during spraying average level of all operations approximated 6 fibres He further assumes that since observations in 1969 showed that asbestos materials constituted less than half of insulating materials then would be under used the time weighted 3 3 fibres average of exposure The levels of dust concentrations quoted for such operations bear no relation to those meticulously observed and measured in the United Kingdom notably by Harries and H.M. Factory Inspectorate In the same paper Selikoff himself agrees that the effect of peak exposures may be considerable and that ten minutes of hard work in an atmosphere of 100 fibres may overshadow the biological effect of the rest of the working day in environmental concentrations of 1 fibre This would agree with personal observation of those who have practical experience of fitting and stripping preformed insulation and asbestos spray work Under conditions prevailing in the past the nature of the work made it inevitable that there was frequent but irregular exposure to very high concentrations of dust - at the moment of breaking away an old section of lagging for example The TLV used in the U.K. based on the recommendations of the B.O.H.S. Standards of Hygiene for Chrysotile Asbestos Dust 32 fully recognise the significance of peak exposures and qualifies the average of 2 fibres over four hours to the extent that excess above 12 fibres for any ten minute period is unacceptable | CONCLUSIONS Apart from the study by Wagner which subsequent surveys suggest have not been repeated on the same scale in other crecidolite mining areas there are very few cases of mesothelioma where the cause can be said with certainty to relate exclusively to crocidolite exposure 01032 01032 01032 01032 01032 01032 01032 01032 OATS mr cee ee - an ge oe LT eceanm me rt ee nene RF tere A Oe yo aa who ty A ~" OR kat ere ae ee Omee r rae. 4.3 4.4 -8- Cases of mesothelioma reported throughout the world where an occupational exposure to asbestos usually both amphibole and chrysotile is definite or possible have invariably occurred where concentrations have been very heavy - much heavier than have occurred in U.K. manufacturing industry for very many years Although there continues to be lack of satisfactory evidence the can suggestion is be associated still occasionally made that mesothelioma with short duration of exposure It is acknowledged that mesothelioma is not always caused by asbestos and in the absence of an occupational history there is a temptation to attribute a particular case to some slight and often unspecified exposure in the past Recent work Newhouse 30 indicates mesothelioma is dose related and it is believed that where asbestos is involved - and here again the type of asbestos cannot usually be specified with certainty - a high degree of exposure took place possibly many years ago and in the early years of life Crocidolite and amosite fibres by their nature have tended to be the most favoured for use in thermal insulation particularly during the war years and years of reconstruction after the war use are clearly The various mostly found diseases in areas associated with asbestos where such work has been concentrated Wagner 36 The incidence of the various diseases are therefore more likely to be associated with the excessive concentrations and relatively uncontrolled working conditions whether of chrysotile or amphiboles than with the type of asbestos There does not seem to be any evidence that where such high concentrations are prevented or do not arise that there is any greater risk of asbestos disease with one kind of asbestos than with another "ee. / MS g 11th December 1973 1 033