Metabolism and elimination of methyl, iso- and n-butyl paraben in human urine after single oral dosage

Parabens are used as preservatives in personal care and consumer products, food and pharmaceuticals. Their use is controversial because of possible endocrine disrupting properties. In this study, the authors investigated metabolism and urinary excretion of methyl paraben (MeP), iso-butyl paraben (iso-BuP) and n-butyl paraben (n-BuP) after oral dosage of deuterium-labelled analogues (10mg). Each volunteer received one dosage per investigated paraben separately and at least 2 weeks apart. Consecutive urine samples were collected over 48 h. In addition to the parent parabens (free and conjugated) which are already used as biomarkers of internal exposure and the known but non-specific metabolites, p-hydroxybenzoic acid (PHBA) and p-hydroxyhippuric acid (PHHA), the authors identified new, oxidised metabolites with hydroxy groups on the alkyl side chain (3OH-n-BuP and 2OH-iso-BuP) and species with oxidative modifications on the aromatic ring. MeP represented 17.4% of the dose excreted in urine, while iso-BuP represented only 6.8% and n-BuP 5.6%. Additionally, for iso-BuP, about 16 % was excreted as 2OH-iso-BuP and for n-BuP about 6% as 3OH-n-BuP. Less than 1% was excreted as ring-hydroxylated metabolites. In all cases, PHHA was identified as the major but non-specific metabolite (57.2-63.8%). PHBA represented 3.0-7.2%. For all parabens, the majority of the oral dose captured by the above metabolites was excreted in the first 24 h (80.5-85.3 %). Complementary to the parent parabens excreted in urine, alkyl-chain-oxidised metabolites of the butyl parabens are introduced as valuable and contamination-free biomarkers of exposure.

Authors: Moos RK, Angerer J, Dierkes G, Brüning T, Koch HM. ;Full Source: Archives of Toxicology. 2015 Nov 25. [fusion_builder_container hundred_percent=”yes” overflow=”visible”][fusion_builder_row][fusion_builder_column type=”1_1″ background_position=”left top” background_color=”” border_size=”” border_color=”” border_style=”solid” spacing=”yes” background_image=”” background_repeat=”no-repeat” padding=”” margin_top=”0px” margin_bottom=”0px” class=”” id=”” animation_type=”” animation_speed=”0.3″ animation_direction=”left” hide_on_mobile=”no” center_content=”no” min_height=”none”][Epub ahead of print] ;[/fusion_builder_column][/fusion_builder_row][/fusion_builder_container]