Dietary cadmium exposure and chronic kidney disease: a population-based prospective cohort study of men and women.

The kidney is widely regarded as the critical organ for cadmium toxicity, however, considerable uncertainty remains regarding the clinical significance of the renal effects of cadmium at low levels of exposure. Food is the primary source of cadmium exposure in the general population with tobacco representing an important additional source. We aimed to assess the association between dietary cadmium exposure and chronic kidney disease (CKD) incidence in two large population-based, prospective cohorts of men (Cohort of Swedish Men (COSM)) and women (The Swedish Mammography Cohort (SMC)) with no history of kidney disease. At baseline 1997, men (45-79 years) and women (48-83 years), completed a self-administered questionnaire on diet and lifestyle. Dietary cadmium exposure for each individual was estimated using dietary data and concentrations of cadmium in food. During 13 years of follow-up, we ascertained 599 incident cases of CKD among men (in 481,591 person-years) and 253 cases among women (in 415,432 person-years) through linkage of the cohorts to national inpatient and outpatient registers. Hazard ratios (HR) were calculated using the Cox proportional-hazard regression model. Estimated dietary cadmium exposure was not associated with increased CKD incidence among men HR 0.97 (95% confidence interval (CI): 0.77-1.21) or women HR 0.74 (95% CI: 0.53-1.04), comparing highest tertile with lowest. Our results do not support a strong association between dietary cadmium exposure and CKD at the exposure levels seen in the general population.