Occurrence of parabens and their metabolites in the paired urine and blood samples from Chinese university students: Implications on human exposure

Abstract Parabens, a group of p-hydroxybenzoic acid esters, are extensively used in cosmetics, personal care products, pharmaceuticals, and foodstuff. In the present study, the total forms (free plus conjugated) of four parent parabens, such as methylparaben (MeP), ethylparaben (EtP), propylparaben (PrP), and butylparaben (BuP), and four metabolites, namely methyl protocatechuate (OH–MeP), ethyl protocatechuate (OH–EtP), p-hydroxy benzoic acid (4-HB), and 3,4-dihydroxy benzoic acid (3,4-DHB), were detected in paired urine and blood samples collected from 196 Chinese university students. The median urinary and blood parabens and their metabolites concentrations ranged from 0.24 to 167 ng/mL and from