Among wor kers emp loyed in factories producing carbon graphite products the risk of ca ncer due to expo sure to polyc yclic aromatic hydr ocarbons was estimated . In one cohort (plant A), a ca ncer incidence study was carried out ; the number of cases were not significantly increased for lung cancers [7 cases , sta ndardized inc ide nce ratio (SI R) 79] or for cancers of the upper respiratory an d alimentary tract (10 ca ses, SIR 103). In another co ho rt (plant B), a mortality study was ca

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... ed out ; neither the mort alit y fr om lung cancer [13 deaths, standardized mo rta lity ratio (SMR ) 118] no r tha t fro m upper resp irat o ry an d alimentary trac t cancers (10 deaths, SMR 125) was significantly higher than expected . With in each co hort , a case-referent study was ca rried out. In plant A the odd s ratios were high but non significant for lung cancers (odd s ratio 3.42) and upper respiratory an d alime ntary tract cancers (odd s ratio 2.19) and they showe d a non sign ifica nt relationship with duration of expo sur e. In plant B, the odds rat ios were low for every ca ncer site.