title: Tetrachloroethylene exposure and bladder cancer risk: a meta-analysis of dry-cleaning-worker studies.
abstract: BACKGROUND
  In 2012, the International Agency for Research on Cancer classified tetrachloroethylene, used in the production of chemicals and the primary solvent used in dry cleaning, as "probably carcinogenic to humans" based on limited evidence of an increased risk of bladder cancer in dry cleaners.
  
  
  OBJECTIVE
  We assessed the epidemiological evidence for the association between tetrachloroethylene exposure and bladder cancer from published studies estimating occupational exposure to tetrachloroethylene or in workers in the dry-cleaning industry.
  
  
  METHODS
  Random-effects meta-analyses were carried out separately for occupational exposure to tetrachloroethylene and employment as a dry cleaner. We qualitatively summarized exposure-response data because of the limited number of studies available.
  
  
  RESULTS
  The meta-relative risk (mRR) among tetrachloroethylene-exposed workers was 1.08 (95% CI: 0.82, 1.42; three studies; 463 exposed cases). For employment as a dry cleaner, the overall mRR was 1.47 (95% CI: 1.16, 1.85; seven studies; 139 exposed cases), and for smoking-adjusted studies, the mRR was 1.50 (95% CI: 0.80, 2.84; 4 case-control studies).
  
  
  CONCLUSIONS
  Our meta-analysis demonstrates an increased risk of bladder cancer in dry cleaners, reported in both cohort and case-control studies, and some evidence for an exposure-response relationship. Although dry cleaners incur mixed exposures, tetrachloroethylene could be responsible for the excess risk of bladder cancer because it is the primary solvent used and it is the only chemical commonly used by dry cleaners that is currently identified as a potential bladder carcinogen. Relatively crude approaches in exposure assessment in the studies of "tetrachloroethylene-exposed workers" may have attenuated the relative risks.
authors.affiliation: Section of Environment and Radiation, and.
authors.forename: Jelle
authors.initials: J
authors.lastname: Vlaanderen
authors.forename: Kurt
authors.initials: K
authors.lastname: Straif
authors.forename: Avima
authors.initials: A
authors.lastname: Ruder
authors.forename: Aaron
authors.initials: A
authors.lastname: Blair
authors.forename: Johnni
authors.initials: J
authors.lastname: Hansen
authors.forename: Elsebeth
authors.initials: E
authors.lastname: Lynge
authors.forename: Barbara
authors.initials: B
authors.lastname: Charbotel
authors.forename: Dana
authors.initials: D
authors.lastname: Loomis
authors.forename: Timo
authors.initials: T
authors.lastname: Kauppinen
authors.forename: Pentti
authors.initials: P
authors.lastname: Kyyronen
authors.forename: Eero
authors.initials: E
authors.lastname: Pukkala
authors.forename: Elisabete
authors.initials: E
authors.lastname: Weiderpass
authors.forename: Neela
authors.initials: N
authors.lastname: Guha
mesh_terms: D006801:Humans; D007846:Laundering; D016273:Occupational Exposure; D018570:Risk Assessment; D012997:Solvents / Q000633:toxicity*; D013750:Tetrachloroethylene / Q000633:toxicity*; D001749:Urinary Bladder Neoplasms / Q000139:chemically induced / Q000453:epidemiology*
chemical_list: D012997:Solvents; D013750:Tetrachloroethylene