Urinary biomarkers for assessment of human exposure to monomeric aryl phosphate flame retardants

• Published in: Environment international Vol. 124; pp. 259 - 264
• Main Authors: Zhao, Fanrong, Kang, Qiyue, Zhang, Xiaohua, Liu, Jiaying, Hu, Jianying
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01.03.2019; Elsevier
• Subjects: Biomarkers; blood; blood sampling; confidence interval; enzymatic hydrolysis; epidemiological studies; flame retardants; humans; hydroxylation; Metabolites; Organophosphate flame retardants; organophosphorus compounds; phosphates; products and commodities; Temporal variability; urine; Biomarkers; Organophosphate flame retardants; Metabolites; Temporal variability
• DOI: 10.1016/j.envint.2019.01.022
• ISSN: 0160-4120; 1873-6750

While monomeric aryl organophosphate flame retardants (m-aryl-OPFRs) are used worldwide in a variety of consumer products, specific biomarkers for epidemiologic studies are lacking. To explore the potential of urinary hydroxylated metabolites of m-aryl-OPFRs as the biomarkers, we detected triphenyl phosphate (TPHP), 2-ethylhexyl diphenyl phosphate (EHDPP), and tricresyl phosphate (TCrP) in 259 whole blood samples and their 5 hydroxylated and 2 diester metabolites in the paired urine samples from the general population. 2-Ethyl-5-hydroxyhexyl diphenyl phosphate (5-OH-EHDPP), 4-hydroxyphenyl diphenyl phosphate (4-OH-TPHP), and 3-hydroxy-4-methylphenyl di-p-tolyl phosphate (3-OH-MDTP) were detected in >80% of urine samples after enzymatic hydrolysis of conjugates, and their concentrations showed significant positive correlations with the blood concentrations of their corresponding parent compounds, respectively. To characterize the temporal reliability, the m-aryl-OPFRs metabolites were also determined in urine samples repeated nine times from six volunteers over 3 months. Urinary 5-OH-EHDPP showed strong temporal reliability (creatinine-corrected intraclass correlation coefficients (ICCs), 0.77; 95% confidence interval [CI], 0.58 to 0.90), and urinary 3-OH-MDTP (creatinine-corrected ICC, 0.52; 95% CI, 0.37 to 0.87) and 4-OH-TPHP (0.56; 95% CI, 0.32 to 0.80) showed moderate-to-strong temporal reliability, while relatively weak temporal reliability was found for urinary DPHP (creatinine-corrected ICC, 0.37; 95% CI, 0.12 to 0.62). This study confirmed specific, reliable, and frequently detected biomarkers for TPHP and EHDPP and developed new biomarker of TCrP for future epidemiological research on health effects of m-aryl-OPFRs. •Hydroxylated metabolites of m-aryl-OPFRs were frequently detected in 259 urine samples.•Concentrations of urinary hydroxylated m-aryl-OPFRs positively associated with their corresponding parents in blood.•Urinary hydroxylated m-aryl-OPFRs showed relatively strong temporal reliability to diesters.