where Csum (μmol/L) is the sum of total molar concentrations of p-HB and Σparabens; MeP% and PrP% are the mole percentages of total concentrations MeP and PrP; MW (molecule weight) is 152 (for MeP) or 180 (for PrP); and V is the daily urine output of 0.66 L (for children) or 1.7 L (for adults), as reported in previous studies.