Estimation of daily cadmium intake from cadmium in blood or cadmium in urine

Objectives It would be quite convenient if daily dietary cadmium intake (Cd-D) can be estimated either from Cd in blood (Cd-B) or from Cd in urine (Cd-U). The aim of the study was to examine if Cd-D can be estimated from Cd-B or Cd-U. Methods The data available in a previous publication were employed for regression analyses between Cd-D and Cd-B, and between Cd-D and Cd-U. 30 sites in various prefectures throughout Japan were surveyed and 20 adult women/site on average provided food duplicate, peripheral blood, and second morning urine samples. Geometric means were taken as representative values and employed in regression analyses. Results Cd-D, Cd-B, and Cd-U cr [i.e., Cd-U after correction for creatinine (cr) concentration] distributed in ranges of 12.5–70.5 μg/day, 0.46–3.98 μg/l, and 1.16–11.02 μg/g cr, respectively. A close correlation was observed between Cd-D and Cd-B, and also between Cd-D and Cd-U cr with r = 0.76 and r = 0.79 ( p < 0.001 for both), respectively. Both regression lines passed close to the origins. Application of 1.23 μg Cd/l blood and 1.26 μg Cd/g cr in urine (average levels for adult Japanese women) to the regression equations gave 16.5 and 11.5 μg Cd/day. Conclusions The analyses suggested that it may be possible to estimate Cd-D from Cd-B or Cd-U. Cd-B-based estimation should be more respected. As variations in the estimation parameters and estimated values are inherent to field surveys, care should be taken in the application of the study results. Application on a group basis (and not on an individual basis) should be considered.