Report of the Scientific Committee of the Spanish Agency for Food Safety and Nutrition (AESAN) in relation to the assessment of the risk of exposure for the Spanish population to cadmium resulting from the consumption of food

Cadmium (Cd) is a heavy metal found as an environmental contaminant, both through natural occurrence and from industrial and agricultural sources. Foodstuffs are the main source of cadmium exposure for the non-smoking general population. Cd absorption after dietary exposure in humans is low (3-5%) but Cd is efficiently retained in the kidney and liver in the human body, with a very long biological half-life ranging from 10 to 30 years. Cd is primarily toxic to the kidney, especially to the proximal tubular cells where it accumulates over time and may cause renal dysfunction. Cd can also cause bone demineralization, either through direct bone damage or indirectly as a result of renal dysfunction. After prolonged and/or high exposure the tubular damage may progress to decreased glomerular filtration rate, and eventually to renal failure. Cd levels in urine are widely accepted as a measure of the body burden and the cumulative amount in the kidneys. The IARC (International Agency for Research on Cancer) has classified Cd as a human carcinogen (Group 1) on the basis of occupational studies. Newer data on human exposure to Cd in the general population have been statistically associated with increased risk of cancer such as in the lung, endometrium, bladder, and breast. A provisional tolerable weekly intake (PTWI) for cadmium of 7 μg/kg body weight (b.w.) per week was established by JECFA (Joint FAO/WHO Expert Committee on Food Additives), this PTWI was maintained pending further research. The EFSA CONTAM Panel (European Food Safety Authority) carried out a meta-analysis on a selected set of studies to evaluate the dose-response relationship between urinary cadmium and urinary s-2-microglobulin (B2M). B2M, a low molecular weight protein, is recognized as the most useful biomarker in relation to tubular effects. A Hill model was fitted to the dose-response relationship between urinary cadmium and B2M for subjects over 50 years of age and for the whole population. From the model, a BMDL5 (Benchmark dose lower limit) of 4 μg Cd/g creatinine was