Levels and determinants of urinary cadmium in general population in Spain: Metal-MCC-Spain study

Cadmium is a ubiquitous and persistent metal, associated with different harmful health effects and with increased morbidity and mortality. Understanding the main sources of exposure is essential to identify at risk populations and to design public health interventions. To evaluate cadmium exposure in a random-sample of general adult population from three regions of Spain, assessed by the urinary cadmium (U–Cd) concentration, and to identify its potential determinants and sex-specific differences, including sociodemographic, lifestyle and dietary factors. We measured U–Cd (μg/g creatinine) in single urine spot samples from 1282 controls enrolled in the multicase-control study in common tumors in Spain (MCC-Spain) with inductively coupling plasma-mass spectrometry equipped with an octopole reaction systems (ICP-ORS-MS). The association between sociodemographic, lifestyle, and dietary characteristics and U–Cd concentrations was evaluated using geometric mean ratios (GMR) estimated by multiple log-linear regression models. Overall, geometric mean U–Cd concentration was 0.40 (95%CI: 0.38, 0.41) μg/g creatinine. Levels were higher in women than in men (GMR]: 1.19; 95%CI: 1.07, 1.32), and increased with age in males (ptrend< 0.001). Cigarette smoking was clearly associated to U–Cd levels (GMRformer vs non-smokers: 1.16; 95%CI: 1.05, 1.29; GMRcurrent vs non-smokers: 1.42; 95%CI: 1.26, 1.60); the relationship with secondhand tobacco exposure in non-smokers, was restricted to women (pinteraction = 0.02). Sampling season and region also seemed to influence U–Cd concentrations, with lower levels in summer (GMRsummer vs average: 0.79; 95%CI: 0.71, 0.88), and higher levels in North-Spain Asturias (GMRAsturias vs average: 1.13; 95%CI: 1.04, 1.23). Regarding diet, higher U–Cd concentration was associated with eggs consumption only in men (pinteraction = 0.04), just as rice intake was associated in women (pinteraction = 0.03). Conclusion: These results confirmed that tobacco exposure is the main modifiable predictor of U–Cd concentrations, and remark that the role of dietary/sociodemographic factors on U–Cd levels may differ by sex. •Smoking status is the main modifiable predictor of U-Cd concentrations.•Secondhand smoke exposure could be an important source of cadmium exposure in women.•Dietary variables explain a small proportion of total variation in U-Cd levels.•Regional/seasonal differences in U-Cd levels suggest environmental factors involved.