Occurrence of cyclotriphosphazene derivatives in human urine: Assessment of human exposure

Cyclotriphosphazene derivatives, commonly employed as flame retardants and electrolyte additives in lithium-ion batteries, have sparked concerns regarding their potential effects on human health due to environmental release. Despite their widespread use, the detection of these compounds in human urine, a key medium for evaluating exposure to environmental pollutants, remains underexplored. In this study, seven cyclotriphosphazene derivatives were analyzed in urine samples obtained from 238 individuals residing in Hangzhou City, China. Results showed that hexafluorocyclotriphosphazene (HFCTP; mean 1.2 ng/mL, range < LOD-7.7 ng/mL) and ethoxy(pentafluoro)cyclotriphosphazene (EPFCTP; 0.96 ng/mL, < LOD-11 ng/mL) were the predominant cyclotriphosphazene derivatives in human urine. Male subjects (0.96 ± 0.33 ng/mL) had much higher (p = 0.029) mean urinary levels of pentafluoro(phenoxy)cyclotriphosphazene (PFPCTP) compared to female subjects (0.56 ± 0.23 ng/mL). We observed a significantly negative relationship between age of participants and their urinary concentrations of HFCTP (p < 0.01) and PFPCTP (p < 0.01). HFCTP had the highest mean daily exposure value (51 ng/kg bw/day), which was followed by EPFCTP (35 ng/kg bw/day) and PFPCTP (30 ng/kg bw/day). As far as we are aware, this is the first study to provide a comprehensive analysis of urinary occurrence and concentrations of cyclotriphosphazene derivative in the general population, which is necessary to conduct a thorough human risk assessment.