Toxicity of tris(2-chloroethyl) phosphate in Daphnia magna after lifetime exposure: Changes in growth, reproduction, survival and gene transcription.

In recent years, with the elimination of brominated flame retardants (BFRs), the product volume of tris(2-chloroethyl) phosphate (TCEP), as a main substitute of BFRs, was increasing and frequently detected in natural waters. However, the current toxicological studies on TCEP were mainly focused on the partial life stage assessment of model animals, and thus it might underestimate the impact of TCEP on environmental risks. Therefore, the whole-life-stage effects of TCEP on growth, reproduction, survival and gene transcription in Daphnia magna (D. magna) were studied in this study after exposure to environmentally relevant or greater concentrations (500 or 5000 ng/L). It was found that chronic exposure to TCEP at environmental relevant or greater concentrations promoted growth of D. magna and the expressions of genes involved in the pathways associated with growth were significantly up-regulated. TCEP did not affect reproduction of D. magna, but the expressions of some genes screened in reproduction stage were significantly changed. Furthermore, the expressions of genes involved in two heart disease-related pathways were down-regulated at the death stage of D. magna after TCEP exposure for 62 days, suggesting that TCEP delayed the death of D. magna by retarding their heart senility.