Insight into the Bioaccumulation and Biotransformation of Triphenyl Phosphate (TPHP) and Tris(2-butoxyethyl) Phosphate (TBOEP) in Pelophylax nigromaculatus Tadpoles
摘要
Organophosphate esters (OPEs) are ubiquitous in various environmental matrices due to their extensive use as flame retardants and plasticizers in our daily life. Triphenyl phosphate (TPHP) and tris(2-butoxyethyl) phosphate (TBOEP), two typical analogues of OPEs, pose risk to the environment, aquatic organisms and human health. In this study, Pelophylax nigromaculatus tadpoles were selected for a 21-day exposure experiment to determine the bioaccumulation and metabolic pathways of these two substances. The logarithmic concentrations (Log C) of TBOEP in tadpoles exhibited an increase over time, while those of TPHP demonstrated a slightly declining trend. TPHP displayed higher bioconcentration factors compared to TBOEP. Differences in bioaccumulation may be attributed to biotransformation and species variability. There were four TPHP metabolites (TP-251, TP-343a, TP-343b, TP-357) and TBOEP metabolites (TB-415a, TB-415b, TB-429a, TB-429b) identified in tadpoles while three TPHP metabolites (TP-343a, TP-343b, TP-343c) and TBOEP metabolites (TB-299, TB-415a, TB-415b) in water. Among these, TB-415b exhibited the higher potential for bioaccumulation. It can be inferred that TPHP and TBOEP underwent hydrolysis (yielding TP-251 and TB-299), hydroxylation (producing TP-343a/b/c, TB-415a/b and TB-429a), and methylation reactions (generating TP-357 and TB-429b). This study provides significant insights into the bioaccumulation and biotransformation mechanisms of TPHP and TBOEP within amphibians.