Normal variability of 22 elements in 24-hour urine samples. Results from a biobank from healthy non-smoking adults

Background Urine is often used for biomonitoring the exposure to elements. However, most studies report concentrations in spot urine samples, which may not accurately mirror the “gold standard” of complete 24-h (24 h) urine samples. There are relatively few data published for 24 h samples, and little information on the within- and between person variability. Objectives The present study aimed at assessing variability within and between individuals in 24 h excretion for a number of elements in adults from the general population and the typical 24 h excretion of these elements. In addition, we assessed concentrations adjusted for creatinine and specific gravity (SG), and associations between elements. Methods 60 healthy non-smokers (31 women and 29 men) from Sweden, aged 21–64 years, collected all urine during 24 h (split into six separate samples) on two occasions, about one week apart. Concentrations of As, Br, Cd, Co, Cr, Cu, Fe, Hg, Li, Mn, Mo, Ni, P, Pb, S, Sb, Se, Sn, U, V, W, and Zn in urine were analyzed by inductively coupled plasma sector-field mass spectrometry (ICP-SF-MS) and 24 h excretion rates were calculated for each day. The ratio of between-individual variance and the total variance, the intra-class correlation (ICC) was...