A Case–Control Study of Lung Cancer Nested in a Cohort of European Asphalt Workers

Abstract

BackgroundWe conducted a nested case–control study in a cohort of European asphalt workers in which an increase in lung cancer risk has been reported among workers exposed to airborne bitumen fume, although potential bias and confounding were not fully addressed.ObjectiveWe investigated the contribution of exposure to bitumen, other occupational agents, and tobacco smoking to the risk of lung cancer among asphalt workers.MethodsCases were cohort members in Denmark, Finland, France, Germany, the Netherlands, Norway, and Israel who had died of lung cancer between 1980 and the end of follow-up (2002–2005). Controls were individually matched in a 3:1 ratio to cases on year of birth and country. We derived exposure estimates for bitumen fume and condensate, organic vapor, and polycyclic aromatic hydrocarbons, as well as for asbestos, crystalline silica, diesel motor exhaust, and coal tar. Odds ratios (ORs) were calculated for ever-exposure, duration, average exposure, and cumulative exposure after adjusting for tobacco smoking and exposure to coal tar.ResultsA total of 433 cases and 1,253 controls were included in the analysis. The OR was 1.12 [95% confidence interval (CI), 0.84–1.49] for inhalation exposure to bitumen fume and 1.17 (95% CI, 0.88–1.56) for dermal exposure to bitumen condensate. No significant trend was observed between lung cancer risk and duration, average exposure, or cumulative exposure to bitumen fume or condensate.ConclusionsWe found no consistent evidence of an association between indicators of either inhalation or dermal exposure to bitumen and lung cancer risk. A sizable proportion of the excess mortality from lung cancer relative to the general population observed in the earlier cohort phase is likely attributable to high tobacco consumption and possibly to coal tar exposure, whereas other occupational agents do not appear to play an important role.

Assessing cancer hazards of bitumen emissions – a case study for complex petroleum substances

“…Despite these "indicators", a significant incidence of skin cancers was not identified in animal studies with straight run paving bitumen condensate and only weak activity was seen following exposure to roofing fume condensate. Furthermore, an increased incidence of skin tumors was not observed in the IARC Multicenter epidemiology case-controlled cohort study (Olsson et al 2010).…”

“…PAC-induced full functional ligands trigger signal transduction pathways that may "crosstalk" with protein kinases involved in gene expression, phosphorylation and chromosomal regulation (Puga et al 2009 P is immunosuppressive at high doses but can enhance immune response at low doses. Upregulation of AHR in rat lung is seen with exposure to bitumen fume condensate despite low levels of PACs in the aerosol and vapor, but expression of these changes has not been reported to result in lung tumors in rats (Fuhst et al 2007) or increased incidence of lung tumors in studies of humans (Olsson et al 2010). The extensive microarray gene expression profile of rat lung tissue ) following nose-only inhalation to rats to road paving bitumen emissions (Venezuelan 50/70 pen at 170 C, 100 mg/m 3 , 6 h/day for 5 days) demonstrated altered expression of 363 of 20,500 probes with the largest overexpression of CYP1A1 and CYP1B1 genes, genes involved with cellular response to oxidative stress and upregulation of inducible genes with AHR binding sites in their promoter.…”

Effect of Temperature and Process on Quantity and Composition of Laboratory-generated Bitumen Emissions

“…(2,3) A large epidemiologic study conducted by Olsson et al showed no increased incidence of lung cancers for European bitumen industry workers. (4) Inhalation animal studies conducted by Fuhst et al, (5) on air-rectified paving bitumen showed no significant tumor formation in rats. Clark et al (6) summarized recent mouse skin painting study results which highlight that the paving fume condensate was not carcinogenic under their test conditions whereas field-matched Type III Build-Up Roofing Asphalt (BURA) (oxidized bitumen) fume condensate produced a weak tumorigenic response.…”

Review and implications of IARC monograph 103 outcomes for the asphalt pavement industry

“…By far the most extensive epidemiological study of bitumen workers, a study of over 80,000 European bitumen workers in eight countries did not find any link to occupational activities and excess lung cancers (Olsson et al, 2010). The authors investigated the contribution of exposure to bitumen, other occupational agents, and tobacco smoking to lung cancer risk.…”