Reduction in County Population Rates of Sinonasal Cancer Following Improvements in Industrial Hygiene at a Nickel Refinery

Abstract

BackgroundThe Cancer Registry of Norway has virtually complete national data on incident cancers through more than 60 years. In 1973, the Registry published the first study of respiratory cancer among workers at a nickel refinery in Kristiansand, in the county of Vest-Agder. Very high risks had already been found in nickel workers elsewhere (Wales, UK; Ontario, Canada).The Kristiansand refiners had an overall sinonasal cancer rate 28 times the expected, and lung cancer 4.8 times in excess of national background rates. Sinonasal cancer is a rare disease with population rates less than 10–5 in men (world standard), but the rate in surrounding Vest-Agder county was more than doubled (1953–1971). Later improvements in the refinery process and industrial hygiene have been described. We have found suggestions of a downward trend in respiratory cancer among the refiners.MethodsFor this ecological study, we used population data for Vest-Agder and national age-specific rates in men to derive locally expected numbers of sinonasal cancer for six decades (1955–2014). The refinery's health care unit contributed the numbers of sinonasal cancer in workers with local residence.ResultsBefore 1995, sinonasal cancers among present or former employees fully accounted for the excess at the county population level. For the last two decades, county numbers were in line with those expected from the national rates (0.8 and 0.7 of expected).ConclusionLower nickel concentrations and respiratory protection appear to have eliminated the excess of sinonasal cancer, although low background rates may have left a remaining low to moderate risk undetected. Population mobility may also dilute local rates.Potential conflicts of interest:No funding was received for the study. TKG is employed by the Cancer Registry, a governmental institution. SRB is employed by the nickel refinery’s health care unit, required by Norwegian law to act as a free and independent advisor in work environment questions.