Temporal variability of urinary concentrations of phthalate metabolites, parabens and benzophenone-3 in a Belgian adult population.

In the present study, we investigated the temporal within-person variability of the exposure biomarker for phthalates, parabens and benzophenone-3 (BP3) in 32 Belgian adults, each providing 11 urine spots during 4 months. We calculated the intraclass coefficient correlation (ICC), the sensitivity and the specificity to assess the temporal reproducibility and to investigate the predictive ability of the spot measurements for these classes of chemicals. Additionally, we explored the temporal variability of the estimation of the cumulative risk of exposure to phthalates (hazard index; HI). We observed fair ICC ranging from 0.55 to 0.68 for parabens, monoethyl phthalate (MEP), mono-iso-butyl phthalate (MiBP) and BP3, but lower ICC, from 0.20 to 0.49, for monobenzyl phthalate (MBzP), mono-n-butyl phthalate (MnBP), mono-2-ethylhexyl phthalate (MEHP), mono-2-ethyl-5-oxo-hexyl phthalate (5-oxo-MEHP) and mono-2-ethyl-5-hydroxy-hexyl phthalate (5-OH-MEHP). The ICC estimated for HI (0.49) reflected a moderate reproducibility. The measurements in spot samples were moderate to good predictor of the 4-month level of exposure for parabens, MEP, MnBP, MiBP, BP3 and HI (sensitivity ranging from 0.67 to 0.77), but lower predictor for MEHP, 5-oxo-MEHP, 5-OH-MEHP and MBzP (sensitivity ranging from 0.58 to 0.63). The sensitivity could be increased when several spot urinary levels were averaged to predict the long-term level of exposure. Globally, our results indicate that a single spot measurement seems to correctly represent the long-term exposure for parabens, BP3, MEP, MiBP and HI. Additional spot samples seemed to be needed for the proper exposure assessment of the other target compounds.