Document e154oQd4pmwOY51KEE201MJ3p

American Petroleum lnstituts 2101 L Street Norrhwest Wasnington. D.C. 20037 202-457-71 SO Neil1 K. Weaver. M.D.. F.A.C.P. %xIcine and 3tological Science Oireav March 1 4 , 1979 Tot From: Merbers, Benzene Epidemiology Task F o r c e ptc- N e i l 1 K. W h v e r , M.D. The attached ?reprint, "A Retrospective Assessment of Solvent Exposure and t h e R e l a t i o n s h i p t o Lymphatic Leukemia," by Earl N. A r p , J r . , e t a l , i s v e r y i n t r i g u i n g . In e x p l o r i n g the r e l a t i o n s h i p between l y m p h a t i c leukemia and solvent e x p o s u r e s i n t h e rllSSer i n d u s t r y , t h e r e a p p e a r s t o b e an a s s o c i a t i o n w i t h coal-2erived b u t not petroleum-derived) solvents. . _-c cc: Epi6emiolaqy Task Force I. R. Tabershaw, M.D. D. S c h o t t e n f e l d , M.D. J. J. T h o q e , M.D. NKW/ eew An euual oopanunitv emoioyer .:* . " \ t Earl W. Arp, Jr, .. Pmela H. Yolf Edward Hunt Occupational Health Studies Group Schccl o f Public Health University o f Fi'orth C a n l i n a . Chapel Hiil , Forth Carolins. .. .. .. Presented a t -T h e Scgtkezstrrn Occupational Health and ,Safety Conference, h ' i l t o n Head, Z.C., November 9 11, 1978. . Prior research i n occupational he21t h has dmanstrated an apparent / association between leukemia and solvent exposurs in an industria: -1 s e t z i n g . W l i c h a e l , e t a l . ,(7) i q a 1975 Occupational Health Ztudies .. Gmup (OHSG) report, f i r s t damnstrated an ,increased risk of l m h a t i c lzuksrnfa mong rubber wcrkers w i t h a history o f solvent exposure as jtidged by OHSG researchers. The resuits of t h a t study are p E s e n t e d i n Table 1 , w i t h the pp,sumd level of exposure based an Occupational T i t l e fircups (OTG's}, an CHSG s a m e for gm+ing of workers by contact wS'h cwfioi: pradtict components and/or pmcsss equi pnent., kHi chael r,otes . t h a t for som period o f tinte i n the past, benzene was the'solvent of choice i n the industry. . . .. k l f , e t a7., (26' i n a 1977 CHSG study, investigated the sme s e t o f leukemia cases using new occupational t i t l e groups based on mre recent envimrmental data. Results shcwed 2n increased relative risk ' s M ? a r t o that o f the McF!ichael finding f o r one study p o p u l a t i c n , b u t the.1ack o.f ap. a s s o c i a t i o n between leukfinia and soTvent: in another cc!!tpany. An associ'ation between myeloid leukemia and benzene exposura was dmomhted by I n f a n t e , e t a l . , ( 3 ) amiu p l i o f i l m workers exposzd bezveen l?4C and 1949.. .. Xn the OHSG studies, no direct . xea. su: .kents of past benzene or o t h e r solvent exposures were available, 'thus the analyses were bas& on subjective categories assigned by industrial hygienists. Even w i t h 2 hoaaaeneous p u p such as an OTG, however, there exists a grzdient of exposure potential, a s individual jobs w i l l vary w i t h respect t o ex- '. f .a - -- ..' -3- posure by v i r t u e of geographical l o c z t i o n , engineering controls, or work p r ac t i c 2'. !.lc,Ulichae; ncted the need f o r mors detailed infomation about I .3 so?vents used i n the rubber i n d u s t r y i n order t o mre acciIrat21y asstss t h e f r impact on wcrkzr health. The objective of this research project was t o develop a detailed h i s t o r - - . o f solvent usage and potential worker exposure i n a rubber tire p?ant and t o use this i n f o m a t i o n t o reassess the assatfati on of l y q h a t i c 1eukmi-a. and sol vent exposcre, :1 . . __ .. .. . . .. . .. .. .. * . _. .. .. .* .. - . a . . . -* . . . .... . .. .._ -. -5- @f t b 8I I- if g .fj:: c: n .I X r= 0 m w 3 t .'0 ._ N + Ixrl L 0 .X 0 L< eY I 1925 1930 1935 0 9d 4 3 0 -9- n tn c3 2 Y 0 3 0 c5r c) h C3 v1 P0X e 'E: w ..c........e...*..--...t-.. m ..*.r.*.-*..:.s.-.-.:.. 1935 1940 1945 .- . . . .. .. N M _I_ 5 . --:.:*.:.e.*........-..a-.-..-...-:.-..:--......-....'. = E -72- 3 1955 v1 cn 4 0 cx3 .r: 3ee Xa C cli c cz, F FI CY . i955 I Xn 0Y 1921 19 25 tI 1 .I __1 3- _i- -=-- ,...........................-....... a _i = s- .. 1 -. I f 1 1. 1 1. 4 i i I 1930 I f 1 1935 .. c ,1940 I 1945 .. 1950 .R Cm - (s (6 1955 1960 .- . .. .- 1965 1970 I .c .*.*...*........x..-.*...:.....'..., :::::::i -a 5- O. Y ... . . -. . . a I XE Y 1321 1925 -1 7- I1930 1935 1940 1945 1450 *J C > >R.. . -.... -_ .. > w 15 N ? us5 .. . .- 1960 . _. i ... . ... . . 1965 .- .. . .- . _. . . . .. .-. . ~ 1970 .. 1976 , .. . -X c 0 L< 3 R -7 9- - _. c VI t Y 3 U 0 -(-r cp ct c) M 5 ' S.O e0n 5 mc JI 1 f 1976 - 21- Refore this p e r i o d , some ex:rapolstion is mcessary. This can b2 . Jcne w i t h sone confidence since the technoloGy of d r m - b u i l i tirils wzs iiitrodgced a t l e a s t a dzczds e a r l i e r . For t i r e building p r i o r t o ths e a r l j 1930's and f o r cther operations such as tubes, belts, and hoses, v/e do n o t have the j o b classi.fication record, consequmtly a different approach m u s t be taken t o establish exposure potentfa]. The standard '+ fomed, offer clues t o solvent us2 i n a given ptant area, For exarzple, . a s t s t z m e n t that the f i n i s h e d t u b e i s t o be washed with "sotvent X" is probably suff icieRt evidenc'e t o establ i sir contzct between "solv e n t X" ' ami r;n i n d i v i d u a l whose job t i t l e was Tube F i n i s h e r du&g the perid of t h e i n which the stacdar.d -o p e r a t i n g procedure i: an a c t i v e docmer?t, ' Likewise, knowledge that an individual Mas a t i r e b u i l d e r 3 r d t h a t t h 2 'drum cment of t S a t speci'fic period c o n t a i n s "solvent Y*', can be used t o .- - - establish t h a t the builder was potentially exposed t o "solvent Y". - -. .. .. . . . . .. .. . . -. --. -23- Sincr? t h e irncediate interest was the icpact g f benzzne expasure versus other solvent exposur2, it was decided to f o c m on this sin31e dichotmy o f potential s o l v e n t exposurg, Therefore t h e exposure codes shown in Table 3 1wr2 developed ' t o distinguish use o f the ccrzercial .3 s o l vent benzene f r o m a11 other solvents (Mhile recosnizing that.bther solvents nay contilin small quantities o f benzene as a contaninznt). the criteria for assigning each o f t!!e eight codes are included following -- ~ the code 1isting. These critsria snd the data listed above were used t o .* assign one of the eight codes t o eich line o f the 135 work histories involved in the leukemia s t u d y . This port.i-on. c f the study was acfom- plished without the coders being aware o f whether t h 2 history being coded was t h a t o f a case OP control. .- , The assignnent o f p-t m t i a l solvent exposure codes 1 t h r o q h 4 a* j~-2ceeded in a 'straightforward Tanner a s docurentation existed for a71 -1 linos zssigned these four codes. For the period o f time covered by a 1 i c e on a work history, the solvent use charts were consulted to dettr- m i n e which solvents, i f any, were authorized f o r the de7artmF.t indi- catzd. A ::;sitive finding was adequatt t o assign a potential area exposure i n the apprupriate s o l v e n t class, either Cade 2 or 4. - Assi?ncent of a Code 1 exposure required that benzene be authorized . .for I J S ~i n t h a t department during the time covered by the'work history tirz and that the job t i t l e be cleariy associated with solvent use. Job t i t l e s such as fire Builder, t'erent Tires, and Core Cementer s a t i s f i e d I this l a t t e r requirement. Code 3 was assigned in an analogous r a n n w i n departments where benzene was not authorized o r a f t e r the tine a t which the commercial benzene solvent was rmoved fmn use. - 25- TABLE 3 (COST.) CRITER'LA FOR AS37:CXLlIG CODES -SOL Solvent U s e Charts -SO? Standard Operatio;: Procedures -FPS Final Product Spscification -JCX Job Classificarion Recard . !. CODS 1: Assigned when there is d o c u e n t e 2 use of the coIYvercial solvent andI benzene in tha deparment during the j o b period; documted routfie, direct use or h a n h k g of solvent by j o b t i t l e or task v desc=",ption. . . -- . C03Z 2: Cscumentatioa: SOL, SO?, Z S , Jc3 .&sig=ed uhen there is docuztnted prox;?tty to the us2 of :>e counercial solvent b e s z e i e dut-kg the j o b period; b-Js no doex- bated d i r e c t use or h a n d l b z o f solvent by the j c b title or task. CG5E 3: Doc1""~ntttion: SOL, SOP, Z S , JCX Assigned uhen &ere is docuzented us2 o f solvents ia the de2art- ,=eatdur-lng t h e job period; ar,d docuneacsd routine, diracr use or haodling of solvent by the j o b title or taskDocuentatioa: SOL, SOP, FPS, JC3 COTE: 4 : . (-4) Assigned uhen there is doc-entzd p r o m r 7 to solvmt use dur-hg the j o b p e r t o d ; but co doc-aentsd d i r e c t us8 o r h s d X z g .of salvencs by ehe j o b t i t l e ob task; ( 3 ) Assigned when a job t i t l e or task has PO d o c t r e n t d d l z s c r use or handlizg of solvenrs; & is classir'ied. a s IP 3ssis:za:t t3 a job title that Goes. Docucentatioa: SOL, SCP, FPS, JC3 8 .- .. -27- ?lo kcown sol*/ent exposure, a Ccde 7, wds a t t r i h t t d 10 t h ~ ws c~rk h i s t o r ] 1ines 1i s t i n g departiients where no solvent use was authorized o r s u s p c t c d or where the job d e s c r i p t i o n exists and n a k s no reference to solvent-csntaining riaterials. This category lists jobs such.as Warehouse -Y Man, Elevator. Operatar -and Yard Crang Cperatar. Cod2 7 was a l s o assign& those lices carrying job t i t l e s where s o l v m t us2 would not be nomzl t o the o F e r a t i o n even 'though d o c m e n t a t i o n was no; a v a i l a b l e . Job titles falling under this catesory included Cafe Helper, Stem Table, and S p o t Seam bJe7 d2r. Code 9 is e s s e n t i a l l y a m i s s i n g data ccde made necessarl bscause a nmber of j o b s were i n p r o d u c t i o n arzas not covered by t h i s study, i.e., Steel ? d u c t s , and i n areas where the i n v e s t i g a t o r cauld n o t rendcr 2 j?;d~n;entbased on personal i n d u s t r i a1 hygiene experience. In a d d i t i o n , rJ-uale lines ot' work history were simply unintelligible and cculd not be assigned sny other code. Assfgnnmit of a Code 5 1 : 6~ was base4 primarily on the j u d q m t o f the i n v e s t i g i t o r and involved jobs noma1 ly associattd w i t h sol vent us2 such as Painters, DeSreaser Operators, and Electricizns whose matcr'als 7 f s t would n o t be carried i n a company d o c w e n t dwotscl t o pmductien rritcrials. I n t o t a l , the 135 worx histcries included 2163 i n d i v i d u a l lines tc! be coded. Vie d i s t r i b t i t i o n o f codes assigmd.is shcwn i n 'Table 4, Appmximately 80 p e c e n t are docurrented codes while Ccde 9 was invoked 326 times o r 15 p e r c e n t o f the listing, A potentialiy major shortcaqing i n t h i s coding process has to & with the lack of a record specific t o C e m n t House workers. These personnel dispense solvent, m i x and dispense cment t o user departnents, and formulate m i x t u r e s f o r outside shiprant. They a r e assumed t o be --2 9 exposed t o the c u e u l a t i v e solveiit J i r t for the p l m t a t any p o i n t i n tine. HoNever, there i s no way o f k r , w i n q , fro3 tk2 availab?e i n f o r m a t f o n , what' m t 5 r i a l s were being p n c 2 5 s 2 t i f o r outside shipn9n.t: or f o r us2rs entirely outsids of t h e r u b b e r industry. I t czn be asscxned t h a t -3 Cenent iio~sepersonnel were p o t e n t i a ? Jy exposed to a t l e a s t t h e solvents t h a t appear on t h e curnulative l i s t , b u t there is no c e r t a i c t y t h a t they . wer2 not-exposed t o 2 material, such as benzene, a f t e r it was removed fmm p l a n t use. A r z v i w showed t h a t one o f the cases f e l l into t h i s . ,, c a t e g o r y , having been employed &s a. cmsrtt mixer f r t 3 1942 lo 1948. He was coded as a " 3 " - - c o n t x t w i t h solvent 0 t h 2 r t h z n benzene. This may be an under-ctding, however i t is t h e o n l y coding that c c u l d be justified by the data i n nand. One other caution should be mentioned. T h stzndard clp?ratfnS , . procedure d o c m e n t s f o r T i r e Buiiding c o n c t n t r z t e an passager tires a l though n a t e r i a l s 3r2 s p ' e c i f i c a l ly designzted f o r us2 w i t h rtcing .. tires, truth and bus tires, and o t h e r s . N o n e t h E i s s , it is conceivable t h a t the data 2 r E less accurate f o r a plant building truck ar,d bus tires ._ thdn for a passenger t i r e p7ant. Five czses incliidrd in this study had ivcrk e q e r i 6 c c e i n th.e. company's truck tire 91znt- T h r a of t h e s c we're c o n s i d e r e d as benzene- exposed (code I o r 2- ) . i n tLl2 e r l y part of L$e 5-1,d-y, whi7e two who began work i n 1942 wer2 consic!ered "code 3" ex- . posed. I t i s u n l i k e l y b u t possible thdt m'xturcs c c n t a i n i n g s o l v e n t s ' other t h a n t h o s e shown could have been iuthorized f o r the trxk tin .?!act by a spy-: i f i c a t i o n not reviewed f o r this s t 3 d y -- 3 1 .- h VI 0 V 0 Y . ilc I' . ... a ~ g 7 2 ,a l l 15 cases a t :OR paint i n t h e i r work histsries reczived a coding of 7 (No Known So'l vent Exposure), whi 1s only two o f the 15 ever received a coding o f 6 (Judgxent Seccndrry Other Solvent). Ths resttlts i n d i c a t e t h a t Secondary Benzem exposure (Cod2 2) and Primzry Other Solvent exposure (Code 3) are associated w i t h an increased risk o f lym?hatic leukemia, w i t h faurtzen-fold and ten-fold increases , respec- 3 The exposure codes were coriined t o form groupings o f particular .. i n t e r s t : benzene, non-benzene solvent, a l l . solvent (includins ben- zensj, primary solvent, and area solvent exposuns. The resulting ... -_ relative risk e s t i m t e s f o r any work experience w i t h the52 exposurs a r e . siveri in Table 7. Exposure t o the a l l solvents catecorj (codes 1-61 shcws an elevated r a t i o of 17.0 w i t h 14 of the 15 'Iflohatic cas22 ever I cxpused. Primary exposure t o solvents (codes 3 , 3, and 5 ) results i n an elevated r a t i o o f 10.50, ~ h i 7 2ares exposure [codes 2 , 4, and 6 ) shows a r a t i o of cniy 1.60. Benzene, the principal solvent o f interest shcws an e l s l a t e d r a t i o o f 5.09 w i t h eight o f t h e 15 cases havina'dinxz contact o r fn the vicinity of potentia? use a t so= point i n t h e i r woricirq C t k v r s o l v e n t s (codes 3-6) also shcw a strong association w i t h t h e '& disease. AS was mentioned previously, 'chess o t h e r solvents m y contain &maw as a Contaminant, which suggests t ! a t low level c c n c e n t r a t i o n s .. of this .chemical; may be potentially as hazard-ous as the rzw material i t s e l f . 47tsmatively, benzene might not be the active agent, and t h e . production o f the disease might be the result o f exposure t a ' o t h e r salvents, o r som m a t e r i a l comon to both benzene and other solvents. -.- COAL- CASE0 SCL!' EPiTS During t k 2 record search describe4 earlier, a raw m a t e r i a l spsci- 4 f i c z t i o n f o r xylene was found, dated 1939, that listx! a sourct o f 'supply which indicated the chemical zisht he derived from a material Tther than petroleum: According t o Me31er1,(~i)n 15139 armatic solvents b * were coal-based naterials; and according t o the history offered Cy Hzrniltoni2) the ccal-based arcmati'c.solvent industry o f the United 1 States could trace i t s origin t o the ti;nc 05 Korld War I. It seems . passible that t h i s s t u d y may have encountzrzd a s e t or' materizls, aromatic solvents, t h a t were derived f r c m a different source in the 1920's and 1930's thzn those o f more recent years, If so, those r2W materials % could contain a significantly differmt set of contminsnts i n both sccpe and level fmm those sam raw materials o f todzy. f h i s could occur even . t h c q h the materials would carry thg same Generic classi.f_i- czticn-aroiratic solvents--2nd the sa= chmical identity-benzene. - This d u e - fmm the -any's raw mteria? speciffcation led t o a -- search 0: the littrzture f a t t ! e s o u r e g f supply and possible ar'sfn of the aromtic solvents over the study period, According t o the U.S. bmitsne, toluene, sojvent naphtha, xylene-were p r o d u e d fm coal up to .. - the early 1940'5. Toluene was produced f m m petmleum i n 1943, followed by xylenr i n l 9 U . Benzene berme available from petruleum i n 7951. These dates, o f COUFSB~do not i n c l u d e the smal t supply o f aach o f these * f- chemicals which has always been available from petroleum by t'rzctional distillaticn. Probably governed by the economics of t h e two chenicil i .. -37- paralle?*d, of cours2, by the Cement Fcuse. Tire 8uildin: and Stock C u t t i n s show a brief use history as does Miscellaneous Rubber Goods. S i n c e there was no precise d a t e docurented f o r t h e presumd change i n arcmatic supply, any choics will be sorne(~ha"carbitrary. The y,ear I950 rn was chosen a s the assumed cross-cver dats. This date is mid-way between the f i r s t appearance of xylene f.rom. petroleum and thz company's e a r ? i e s t record o f a petroleum-based supplier. It is also the last year of the b . .- coal p r b o n i z a. t i o.n iildustry'.s total domination .. of the domestic benz. e_ne supply. .- * .. .. . .. .. .. -- 9 I t. -43- shcws t h e greatest association vlith a relative risk o f 7.3.3, while t k 2 e l e v a t i o n for benzene is slightly lolcrer a t 5.09. The meastire af associ- aticlc f o r both the xylene and benzzne categories ccsbined, cozgrisfng t h E coal-based solvent, expGsure, is significantly elevated at 5-42. I Nhen only t h e t i g h t controls are considered, the only significzatly e i e v a t a d risk corresponds t o xylene exposure. Another way t o assess the effect o f these difFerent solvent smirtes i s t o assign the cases and cantrols t o nutually exclusive exposure _. 8 severity groups. Table 9 disp'lays the number o f - cas25 and- contmls assigned t o each cztegory, and their rztio. An individual with acy tics ir, t h e Coal Based Solvent category received t h a t severity assiqnmnt, An individual w i t h tim i n t h e Petroletlm Based Solvent category b u t no . . . -.__ Cca: Based Solvent tine was classified as Petroleum Sased eipcsure. Th0.s~with Judgmnt Other Solvent exposure (cudes 5 and 6 ) b u t nevey . tkcocks 1-4 were placed i n Base Unknown cafegory, whi7e those with crlci2s 7 and/or 9 only were No Known Solvent Expasure. b I i t h the.4:l . I. . . matching: r a t i o - or' the-15 cases and 63 controls, a r a t i o of .250 would be . .. .~ . . . _- -_ . expect.~d-, Cnce-again t h e CoztT Qassdcategary shows a n elevated ratio. .~ .. . .. . --.- .- ... - . - - .. . - . ___ . Ffnal'ly, .these findings under t h e coal-based chemical hypothisis are cxanined one further way. Figure 4 skows the fraction of total workforce time spent in each o f t h e potential exposure catqories by oase and c o n t n l . The basis for t h i s chart is the work experience o f 60 contrbfs t o t a l l i n g 22,23T months and 15 cases totaling 5,495 r r ; c l ~ t h ~ . t T>e potentfa1 exposure categories o f t h e e a r l i e r analyses are r q e a t e d on t h i s ehart. .Note that the fourth entry is the combined entry o f - (2) benzene and ( 3 ) xylene and is l a b e l e d Coal-&sed So'lvents. Again, this c,ategory or' exgosure shows a marked c o n t r a s t Setween case and t I .. .. I-ti'.a na'n I wz W czwu m a2 J (D I f W e 'u3 -. .. .. . It'0 .... -' 2 -. ... . ._- .. ..- .-. ... . -... . ._ -. . t a z a c1 b e> a cc IL , DISCUSSION Two p o i n t s should be mentioned w i t h regard t o these f i n d i n g s . First, ' many o f the coal-based exposure individuals continued to work a n d entered petroleum-base exposure categories. Second, many o f the petroleum-derived solvents probably contained a small quantity o f benzene as a contaminant --as do the gasolines o f today, and certainly refined solvent naphtha -' .. --xylene(s) would have contained measurable levels o f benzene. Yet i n a l l t h r e e methods of analysis- - relative risk estimates, severity code assign- - ment, and fyaction o f workforce time--the f i n d i n g s are consistent w i t h the hypothesis of a n a s e n t common'to coal-based materials which i s e i t h e r absent or not present i n sufficient quantity i n petroleum-based solvents t o produce the disease e n t i t y under study. As coal is aromatic i n nature, while petroleum i s more aliphatic (81 i t i s possible t h a t coal-based products would be contaminated by cyclic compounds t o a greater extent than would the petroleum-based counter- p a r t s - AS a cTass a f chenicals, the polycyclic hydrocarbons have few . .. - - peers -_ as ca ncer- cau sing .- a ge . nts - ._--Coa_t _ _is the .- s-our-ce o --- f pro- _d_u-ct_io_n---f_o_--r a-.-- number of poTycycl ic. chemicals. ' A brief 1i t e r a t u r e review o f .the lym- -. ..~ - phatic 1.errkmogens unearthed references to'three material s .apparently capable o f inducing lymphatic leukenria, i n laboratory animals. These three are 9, IO-Dimethyl -7 ,Z-Ben~athracene,(~3) ,4-8enzpyrene, and Metnyl cholanthrene. (lo) Interestingly, a l l three materials were appl ied t o the s k i n o f t e s t animals u s i n g benzene as the solvent c a r r i e r . A l l . three a r e soluble i n the aromatic solvents and would l i k e l y remain i n the commercial material i f no special attenpts were made toward separa- ' tion. T h i s was pointed o u t by Lijinsky and Raha(5) w i t h reference CO;\ICiUSiCN Following e a r l i e r findings by OESG investfgators of an apparent .. a s s c c i a t i o n of lymphatic leukrmia with sclvent-using job groups, an a t t s t p t was made t o extend the analysis throtigh more pr2cis3 estimates of p o t e n t i a l exposure, T h i s was accocplished by a recreation of solvent . .I usc a t ,a rubber tire o?eration-over 2 55-year period, utilizfng caipany- dweIop2d business records. .. When .this precise method o f assigninp potential exposures was applied to indf.vidual workers i n the case-contr3'1 s t ~ G y ,the report& .- association between lymphatic leukeniz and solvent exposum was not a n t ~ re&?fim=dbut was' s u b s t a n t i a l l y strengthened. Whereas Mdichtcl re- ... . partx! relative risks up t u 9 for workem i n the group p r e s ~ s e dt o have high sclvent exposure, t h i s study showed riskestfmates or' 3.5 t o le for w a r h - s exposed t o benzene and 1.75 t o 9.5 for those who contzcted o t h e r . solvents. If the assigned causes &f dsath fqr the cohort a= assmed t o be valid, '&e. fisk OF.. death fmm Tynipnatic.leukernfa does i n d s d ' app-.ezr- -to be associatad-wiA&p6ar history of work with solvent. . - . . _ -._ ~ -. .. - This extension of the solvent-Ieukmia study was mde possible by . . .. .. data extracted frcm records develcped for purpcses far diifemnt frca t o.ccupational health research. These & t a f r c m existfng company records 8 .havr pravidd the capability t o determine the r a w r n a t k a l , location, tirne'and duration of use, and identity o f workers pctential?y i n contact w i t h or in the v i c i n i t y ' o f the potential exposure agents. I n the dbs s x e o f actual workplace measurements, the apqruach pmsented here m.c y o f f e r tke next best alternative. A s s ~ r c ho f cmpany records uncovered . -L . - 5 1 REFEW!CES .. . -. 1. k v i s PA: Tcxic Substances i n the Rubber Industry, Part 2 , Benzol, The ?ubber Ace, 367-368, 1929. 2. Hsrniltzn A: The Growing Henace of Benzene (Benzol) Poisoning in Pnerican I n d u s t r y , Jcurnal of the PIilericzn !!edical. Assmiatson, . 78~627-630,1922. . 3. 'Infaate P, e t a l : Leukemia and Benzene Workers, Lancet, 2-2028: 76-78? i977. 4 . A. Lzw L!J: The Induczion o f Leukemia i n !lice Fo77awing Percutanecrus L p p l i r a t i o n Of 9,10-0imthy1-7,2 Bmzanthracene, Cancer Research, 4 1:5fi&5& l.942, 5. Lijfnsky W; Paha CR: Polycyclic Amratic Hydracarbons i n Comercia1 Sol vents, Toxitofogy and Ago7 i e d Phaxacoloqy , 3:469- . 473, 1967. 6. Pantel ti; Haenszel U: Stttisticti Aspects 'of the Analysis of Data froin RetrosgKtive Studies or' Diszase, J Fiat7 Cancer I n s t i t x t t , 22:7:q-748, 1959. I 7. Ik??icSael AJ, e t a ? : Solvent fixpostlre ahd' Leukemia amng Rubber h r k w 5 : An Epidemiologic Study, Journal o f Octumtiona? Meciicl'ne, . 1?:23;-239, 7975. -. 8.. Wellan I : Handbcak o f Solvents, Vol . 7 , Pure Hydrccarbonr. Reinho?d ?l;oiishing Carp., New York, 1957. . .I U.S. ? ' ~ r i fC'onmission: Census 1,: flyes and of ather S y n t h e t i c Organic C::.~iccals,1930, Report Pfo. 19, Washington, OC, Governmnt P r i n t i n g Uffice, 1931. c . ,' .- -53- !<e c;in tepcrssnt the d a t a for. each s e r i oL a lexkun-ia case ard the four aatckcd c o ~ z t r o l sas Collovs : Exposed . Bot Exposed Totai Ki :+a tctist i coatro1s I IDi xi .. . -'Chc % u t c l Baeeszel Odds Rario for each s e t is: -0.3. AiDi / DiCi =i *E:! frrr p.+.s enzlte s t a i y p o p u l a t i o n te us2: .. .. '. ..