Chromium concentrations in urine (Cr-U) were measured in a total of 664 children in the second through eighth grades. Most of them were living in an urban area of Tokyo where the soil was reported to have been polluted by chromium from a smelter located in the area. Children living in a suburban area were used as controls. There was no constant significant difference by area, as shown in Table 2. The mean Cr-U of the total samples was 0.7μg/l with a standard deviation of 0.6μg/l. The mean value was much lower than those reported by other authors in the 1960s for the general population in Japan and elsewhere but was in the middle range of the 0.4-2.1μg/l reported in more recent years in Japan.
The distribution of our Cr-U data indicated approximately a logarithmic normal pattern similar to results obtained and reported in the past literature. Chance differences of mean Cr-U by age, sex, area and year of determination were sometimes observed, but the differences did not indicate any biological significance.
It was found, however, that the results varied by sample lot and year of determination, and comparisons among different lots or years of determination could not be made in this study. Moreover, individual variation was not observed even within a single lot. More studies on the determination technique are required in the future in order to evaluate slightly different exposures to chromium by individuals using urine.
