Further improvements of XRF analysis of cadmium in vivo

Kidney cadmium as compared to other markers of cadmium exposure in workers at a secondary metal smelter

BACKGROUND

The aim of the study was to evaluate whether cadmium concentrations in kidney (K-Cd), blood (B-Cd) or urine (U-Cd) could reveal previous occupational cadmium exposure at a metal smelter.

METHODS

The study included 90 smelters and 35 controls (B-Cd and U-Cd determination). In a subgroup (N = 33), K-Cd was also determined.

RESULTS

B-Cd (median 4.6; range 0.5-53 nmol/L), U-Cd (0. 29; 0.04-1.9 micromol/mol creatinine) and K-Cd (14; 3-61 microg/g wet weight) were similar to reported concentrations in the general Swedish population. In the subgroup, significant associations (P<0. 001) were obtained between B-Cd and K-Cd (r = 0.70), U-Cd and K-Cd (r = 0.60) and between U-Cd and B-Cd (r = 0.62). Multiple regression analyses revealed smoking as the major predictor of K-Cd, B-Cd, and U-Cd. B-Cd and U-Cd were both associated with the duration of employment at the smelter.

CONCLUSIONS

There was no statistically significant evidence of previous occupational exposure at the smelter from measurement of K-Cd.

Cadmium in kidneys in Swedes measured in vivo using X-ray fluorescence analysis

An X-ray fluorescence (XRF) technique using plane polarized X-rays for excitation was used for in vivo measurements of cadmium in the kidney cortex among non-occupationally exposed members of the general population in southern Sweden. The measured concentrations of cadmium in the kidney cortex of smokers (median 28 micrograms/g, n = 10) were significantly higher (P = 0.0036) as compared to those in non-smokers (median 8 micrograms/g, n = 10), and so were the cadmium concentrations in blood and urine. The results show that smoking considerably increases the cadmium concentration in the kidney cortex and that smoking is a major source of cadmium exposure in the general population of Sweden. Except in the presence of very deeply situated kidneys, where the minimum detectable concentration is high, non-invasive in vivo XRF analysis of kidney cadmium should be a useful tool for evaluating the effects of long-term low-level exposure to cadmium and the risk of kidney damage.

Further scientific issues in determining an occupational standard for cadmium

This contribution responds to the recent paper of Thun et al. (American Journal of Industrial Medicine 20:629-642, 1991) on an occupational standard for cadmium. The contribution of non-invasive in situ measurements of cadmium in liver and in kidney to the study of cadmium industrial toxicology is particularly reviewed. It is contended that clear scientific grounds do not exist for recommending cadmium in air occupational standard below 10 micrograms m-3, and that other arguments would need to be adduced to support a recommendation for a lower level. Last, a number of unanswered questions are identified and the need for further work is highlighted.