Document XRZoV1w9pYVeLEvV0RDYOZJQ4

MALIGNANT L Y M P M S AMONG RUBBER AND T I R E INDUSTRY WORKERS: A CASE-CONTROL ANALYSIS WITHIN A COCH3RT STUDY c MALIGNANT LYMPHOMS AMONG RUBBER AND TIRE INDUSTRY MRKERS: A CASE-CONTROL ANALYSIS WITHIN A COHORT STUDY i' i EX ECUTIVE SUMMARY An e a r l i e r study o f leukemia deaths had given evidence t h a t lyrn- c p h a t i c leukemia was associated, i n one of t h e companies, w i t h solvent exposure jobs, w h i l e each company had some e l e v a t i o n o f m o r t a l i t y rates f o r deaths from neoplasms of lymphatic and hematopoietic tissue, compared w i t h those for the general U.S. population. This report presents the f i n d i n g s o f an epidemiologic study o f malignant lymphomas among workers i n four major rubber and t i r e manufacturing companies. The main o b j e c t i v e of the study was t o i n v e s t i g a t e the hypothesis t h a t workers i n jobs i n v o l v i n g exposure t o solvents were a t increased r i s k o f developing lymphoma. The r e s u l t s of a case- control study of malignant lymphomas showed t h a t associations were found between h i s t o r i e s o f working i n areas w i t h p o t e n t i a l solvent exposure and deaths a t t r i b u t e d t o lymphomas. The associations detected were strongest between h i s t o r i e s consistent w i t h high solvent exposure and f a t a l lymphosarcoma. When solvent OT's were analyzed i n d i v i d u a l l y , T i r e B u i l d i n g showed the strongest association w i t h a l l lymphmas combined and lymphosarcoma i n p a r t i c u l a r . Considering the l a r g e number o f people working i n T i r e B u i l d i n g special a t t e n t i o n should be paid t o minimizing exposures t o solvents i n t h i s work area. O f p a r t i c u l a r importance i s the f i n d i n g t h a t refinement of poten- t i a l exposure data i n Company A leads t o stronger associations between past p o t e n t i a l benzene exposure and lymphosarcomas. i I ! t The results presented suggest t h a t h a v i n g worked i n certain potent i a l solvent exposure areas in the rubber and t i r e manufacturing process increased the risk o f developing lymphosarcomas and "other lymphomas." Potential direct benzene exposure in the past seems t o have been a major P factor. This report will be followed by a more extensive set o f analyses which w i l l include tests of latency and dose response functions. ii 70 6.3.2 Relative risk estimates for solvent exposure assessment scheme, based on product utilization i nformation The more refined solvent exposure scheme i s t o date only available for Company A . O R ' s were calculated for a l l 60 lymphoma -and leukemia cases and the respective subentities. The hypothesis t h a t refined exposure data lead t o stronger associations between solvent exposure and lymphomas is fully supported. The strongest association was found for potential benzene exposure >5 years and lymphosarcoma, revealing a n OR o f 12.0 (95%C.I. 2.86, 50.37; ~40.005)(Table 1 1 ) . 6.3.3 Dose-response relationship The associations found between solvent exposure and lymphanas were consistently stronger for High Solvent Groups compared t o Medium and Low Solvent Groups. A scoring system combining intensity o f exposure with duration of exposure i s currently being developed t o t e s t for a dose-response re1ationshi p between solvent exposure and lymphomas; 1atency analyses a1 so are underway. 7. Discussion The results o f a case-control study of malignant lymphomas i n four plants of four major rubber and t i r e manufacturing companies have been presented. Briefly sumnarized overall findings of the present study are given in Table 12. Associations were found between histories o f working i n areas w i t h potential solvent exposure and deaths attributed t o lymphomas. The associations detected were strongest between histories consistent with High solvent exposure and fatal lymphosarcoma. 11 When solvent OTIS were analyzed i n d i v i d u a l l y , T i r e B u i l d i n g showed the strongest association w i t h a11 lymphomas combined and lymphosarcoma i n p a r t i c u l a r . Considering the l a r g e number o f people working i n T i r e Building special a t t e n t i o n should be paid t o minimizing exposures t o r solvents i n t h i s work area. O f particular importance i s the finding that refinement of poten- t i a l exposure data i n Company A leads t o stronger associations between past p o t e n t i a l benzene exposure and lymphosarcomas. C1ear dose-response re1a t i o n s h i ps between sol vent exposure OTG' s and lymphomas were n o t found. However stronger associations a r e always present i n High Solvent Group compared t o Medium and Low Solvent Group. The r e s u l t s presented sugqest t h a t having worked i n c e r t a i n p o t e n t i a l solvent exposure areas i n t h e rubber and t i r e manufacturing process increased the r i s k o f developing lymphosarcomas and " other lymphomas." P o t e n t i a l d i r e c t benzene exposure i n t h e past seems t o have been a major f a c t o r . The associations found are s i y i l a r t o those f o r lymphatic leukemia. Besides studies on Swedish and American chemists and American aluminum reduction p l a n t workers t h i s i s one o f t h e few epidemiologic studies on chemical lymphomogenesis; i t supports the view t h a t c e r t a i n lymphomas may be occupationally induced, and i d e n t i f i e s p o t e n t i a l benzene exposure as a p a r t i c u l a r hazard.