title: Unrecognized risks of nickel-related respiratory cancer among Canadian electrolysis         workers.
abstract: OBJECTIVE
  Nickel compounds, inclusive of water-soluble salts, have been classified as human carcinogens by         the International Agency for Research on Cancer (IARC). Nickel producers have disputed the classification of soluble         nickel compounds for three decades with reference to an alleged absence of excess respiratory cancer among Canadian         nickel-exposed electrolysis workers. We evaluated historical data from two electrolytic refineries in Ontario, both         included in prominent Canadian reports on occupational nickel-related cancer.
  
  
  METHODS
  For Port Colborne nickel         refinery (PCNR) and Copper Cliff copper refinery (CCCR), we identified process descriptions, exposure estimates, and         original reports on cancer mortality using reference lists, libraries, and state archives. The documents were written         or published between 1930 and 1992.
  
  
  RESULTS
  For PCNR, a 1977 US National Institute of Occupational Safety and Health         criteria document demonstrated an excess nasal cancer risk among electrolysis workers independent of furnace exposure.         PCNR studies published after 1980 excluded 26% of long-term refiners who died from respiratory cancer according to         earlier reports, and 42% of the workers had unknown vital status at the end of follow-up, biasing the standardized         observed-to-expected mortality ratios downwards, most pronounced in recent reports and for workers without pension or         company benefits. CCCR reports did not adequately address soluble nickel exposure in the evaluation of an observed         occupational lung cancer excess.
  
  
  CONCLUSIONS
  While acknowledging important contributions to the recognition of nickel         carcinogenicity from highly exposed Canadian refiners, we conclude that the claimed absence of nickel-related         respiratory cancer among electrolysis workers has resulted from an arbitrary overemphasis of biased and inconclusive         findings.
authors.affiliation: Department of Research, Cancer Registry of Norway, PB 5313 Majorstuen, NO-0304 Oslo, Norway. tom.k.grimsrud@kreftregisteret.no
authors.forename: Tom K
authors.initials: TK
authors.lastname: Grimsrud
authors.forename: Aage
authors.initials: A
authors.lastname: Andersen
mesh_terms: D002170:Canada; D002273:Carcinogens / Q000633:toxicity*; D015331:Cohort Studies; D004572:Electrolysis; D006801:Humans; D008175:Lung Neoplasms / Q000139:chemically induced*; D009532:Nickel / Q000633:toxicity*; D012307:Risk Factors
chemical_list: D002273:Carcinogens; D009532:Nickel