Variability of urinary cadmium excretion in spot urine samples, first morning voids, and 24 h urine in a healthy non-smoking population: Implications for study design
When selecting the least biased exposure surrogate, for example, the concentration of a biomarker in a urine sample, information on variability must be taken into consideration. We used mixed-effects models to estimate the variability and determinants of urinary cadmium (U-Cd) excretion using spot urine samples collected at six fixed times during 2 days about 1 week apart, from 24 healthy non-smok
