 the russian nickel refineries located in the cities of nikel and zapolyarny close to the norwegian border are responsible for extensive sulfur dioxide and nickel pollution , as well as severe ecological damage in both countries . 
 the aim of our study was to investigate human nickel exposure in the populations living on both sides of the norwegian - russian border . 
 the design was a cross - sectional population - based study of adults aged 18 - 69 years residing in sor - varanger municipality , norway , and nikel and zapolyarny , russia , during 1994 and 1995 . individual exposure to nickel was assessed by measurements of nickel in urine using electrothermal atomic absorption spectrometry . for controls , 
 urine was collected from adults in the russian cities of apatity and umba ( kola peninsula ) and the norwegian city of tromso , all of which are locations without nearby point sources of nickel . 
 altogether 2,233 urine specimens were analysed for nickel . 
 people living in nikel had the highest concentrations ( median 3.4 microg / l ) , followed by umba ( median 2.7 microg / l ) , zapolyarny ( median 2.0 
 microg / l ) , apatity ( median 1.9 microg / l ) , tromso ( median 1.2 
 microg / l ) , and sor - varanger ( median 0.6 microg / l ) . 
 regardless of geographical location , the russian study groups all had a higher urinary - nickel average than those in norway ( p<0.001 ) . 
 with the exception of nikel , neither the russian nor the norwegian urinary - nickel levels were associated with residence location near a russian nickel refinery . 
 we concluded that industrial nickel pollution alone could not explain the observed discrepancy between norway and russia ; we also discuss other possible nickel exposure sources that may account for the high urinary levels found in russia.imagesfigure 1figure 2figure 3figure 4figure 5 
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