Characteristic Profiles of Urinary p-Hydroxybenzoic Acid and its Esters (Parabens) in Children and Adults from the United States and China

Abstract

Hydroxybenzoic acid esters (parabens) are used as preservatives in foods, cosmetics, and pharmaceuticals, which results in the exposure of humans to these compounds. Parabens and its metabolite, p-hydroxybenzoic acid (p-HB) are excreted from urine in free and conjugated forms. In this study, free and total forms (free plus conjugated) of parabens and their common metabolite, p-HB, were measured in urine samples collected from U.S. children (n = 40), Chinese children (n = 70), and Chinese adults (n = 26). The median concentrations of the sum of 6 parabens (Σparabens) in urine from U.S. and Chinese children were 54.6 and 10.1 ng/mL, respectively. The median concentration of urinary parabens measured for Chinese adults was 33.2 ng/mL, which was lower than that reported for U.S. adults. Elevated concentrations of parabens (1000-10,000 ng/mL) were found in urine from some Chinese adult females. Parabens were present predominantly (>90%) as conjugated species in urine. Among the six parabens analyzed, methyl paraben (MeP) and propyl paraben (PrP) were the predominant compounds, which accounted for 57-98% and 1.4-12%, respectively, of the total concentrations. A significant positive correlation was found between the concentrations of MeP and PrP. The geometric mean (GM) concentration of p-HB was 1380 and 2370 ng/mL for Chinese children and adults, respectively. The GM concentrations of p-HB in urine from U.S. children were 752 ng/mL for girls and 628 ng/mL for boys, which were 2-3 times lower than the concentrations determined for Chinese children. There was a significant difference in the ratios of concentrations of Σparabens and p-HB between demographic groups, which suggested the existence of various exposure routes to parabens. Based on the concentrations of urinary parabens and p-HB, the daily intake (DI) of MeP and PrP was estimated. The GM DI(MeP) estimated for Chinese children was 0.5-0.7 mg/day, which was similar to those determined for U.S. children. The GM DI(PrP) (0.2-0.5 mg/day) estimated for Chinese children was 20- to 50-fold higher than the value determined for U.S. children (0.01 mg/day). The highest exposure to parabens was found for Chinese adult females, with GM DI(MeP) and DI(PrP) of 5.9 and 1.2 mg/day, respectively. Elevated exposure to PrP was found in some Chinese adult females (27 mg/day) and children (11 mg/day).

The associations of triclosan and paraben exposure with allergen sensitization and wheeze in children

“…These exposures likely originate from consumer products; therefore, the associations may have important implications across populations. Mean triclosan and paraben levels were similar to those reported in other studies of U.S. children, [23][24][25] but triclosan was more frequently detected in these U.S. children than in Norwegian children. 18 Because these chemicals are nonpersistent in the body, urine concentrations are reflective of exposure at a single time.…”

Parabens in 24h urine samples of the German Environmental Specimen Bank from 1995 to 2012

“…Because p-hydroxybenzoic acid is a non-specific metabolite common to all parabens, human biomonitoring studies have focussed on analyzing the specific parabens (after hydrolysis) in urine as biomarkers of internal exposure (Ye et al, 2006;Moos et al, 2014). Recent biomonitoring studies have shown that these parabens are ubiquitously present in urine samples from the general population and various sub-populations (Ma et al, 2013;Asimakopoulos et al, 2014;Frederiksen et al, 2010Frederiksen et al, , 2013Frederiksen et al, , 2014CDC, 2015;Calafat et al, 2010;Casas et al, 2011;Philippat et al, 2012;Dewalque et al, 2014;Wang et al, 2013;Shirai et al, 2013;Kang et al, 2013;Meeker et al, 2013).…”

Occurrence of parabens in foodstuffs from China and its implications for human dietary exposure

“…The presence of parabens in urine samples from Spain and Denmark also was documented Frederiksen et al, 2011). Studies have reported the occurrence of parabens in human plasma, serum, and milk at concentrations on the order of a few nanograms per milliliter (Frederiksen et al, 2011;Schlumpf et al, 2010;Wang et al, 2013;Ye et al, 2008). Nevertheless, information on the occurrence of parabens in foodstuffs and other source of human exposure is still scarce.…”