Tissue distribution and trophic transfer of organophosphate triesters and diesters in three marine mammals of the Liaodong Bay and the Northern Yellow Sea

Biomagnification potential and health risks of organophosphate esters in prey to humpback dolphins based on dietary correction

Information on the biomagnification of organophosphate esters (OPEs) is limited, and the results are inconclusive, mainly because precise predatorprey relationships have not been determined. Herein, we first evaluated the biomagnification potential and dietary exposure risk of 15 OPEs in 14 prey species (n = 234) to Indo-Pacific humpback dolphins from the northern South China Sea using quantitative fatty acid signature analysis (QFASA). QFASA identified Chinese gizzard shad as the primary prey of dolphins. Among the 15 OPEs, 86.7 % (13/15) had a diet-adjusted biomagnification factor (BMFQFASA) greater than 1, indicating the biomagnification potential between dolphins and their diet. Moreover, BMFQFASA exhibited a considerable positive correlation with the log octanolwater partitioning coefficient of OPEs, indicating that lipophilicity may affect the bioamplification of OPEs. Risk assessments showed that although current OPE levels may not pose substantial health risks to dolphins via diet intake, the nondiet-adjusted hazard quotient/hazard index underestimated the exposure risk of OPEs to this vulnerable dolphin species. This study provides novel evidence regarding the biomagnification and dietary exposure risks of OPEs in cetaceans, emphasizing the importance of estimating the dietary composition of predators in such analyses.

Integrated RNA sequencing and biochemical studies reveal endoplasmic reticulum stress and autophagy dysregulation contribute to Tri (2-Ethylhexyl) phosphate (TEHP)-induced cell injury in Sertoli cells

Tri (2-Ethylhexyl) phosphate (TEHP), widely used as a fire retardant and plasticizer, has been commonly found in the environment. Its potential health-related risks, especially reproductive toxicity, have aroused concern. However, the potential cellular mechanisms remain unexplored. In this study, we aimed to investigate the molecular mechanisms underlying TEHP-caused cell damage in Sertoli cells, which play a crucial role in supporting spermatogenesis. Our findings indicate that TEHP induces apoptosis in 15P-1 mouse Sertoli cells. Subsequently, we conducted RNA sequencing analyses, which suggested that ER stress, autophagy, and MAPK-related pathways may participate in TEHP-induced cytotoxicity. Furthermore, we demonstrated that TEHP triggers ER stress, activates p38 MAPK, and inhibits autophagy flux. Then, we showed that the inhibition of ER stress or p38 MAPK activation attenuates TEHP-induced apoptosis, while the inhibition of autophagy flux is responsible for TEHP-induced apoptosis. These results collectively reveal that TEHP induces ER stress, activates p38, and inhibits autophagy flux, ultimately leading to apoptosis in Sertoli cells. These shed light on the molecular mechanisms underlying TEHP-associated testicular toxicity.

Fugacity- and biotransformation-based mechanistic insights into the trophic transfer of organophosphate flame retardants in a subtropical coastal food web from the Northern Beibu Gulf of China

The bioaccumulation and trophic transfer of organophosphate flame retardants (OPFRs) in marine ecosystems have attracted great attention in recent research, but our understanding of the trophic transfer mechanisms involved is limited. In this study, we investigated the trophodynamics of OPFRs and their metabolites in a subtropical coastal food web collected from the northern Beibu Gulf, China, and characterized their trophodynamics using fugacity- and biotransformation-based approaches. Eleven OPFRs and all seven metabolites were simultaneously quantified in the shellfish, crustacean, pelagic fish, and benthic fish samples, with total concentrations ranging from 164 to 4.11 × 104 and 4.56-4.28 × 103 ng/g lipid weight, respectively. Significant biomagnification was observed only for tris (phenyl) phosphate (TPHP) and tris (2-ethylhexyl) phosphate (TEHP), while other compounds except for tris(2-chloroethyl) phosphate (TCEP) displayed biomagnification trends based on Monte Carlo simulations. Using a fugacity-based approach to normalize the accumulation of OPFRs in biota to their relative biological phase composition, storage lipid is the predominant biological phase for the mass distribution of 2-ethylhexyl diphenyl phosphate (EHDPHP) and TPHP. The water content and structure protein are equally important for TCEP, whereas lipid and structure protein are the two most important phases for other OPFRs. The mass distribution of these OPFRs along with TLs can explain their trophodynamics in the food web. The organophosphate diesters (as OPFR metabolites) also displayed biomagnification trends based on bootstrapped estimation. The correlation analysis and Korganism-water results jointly suggested the metabolites accumulation in high-TL organisms was related to biotransformation processes. The metabolite-backtracked trophic magnification factors for tri-n‑butyl phosphate (TNBP) and TPHP were both greater than the values that accounted for only the parent compounds. This study highlights the incorporation of fugacity and biotransformation analysis to characterize the trophodynamic processes of OPFRs and other emerging pollutants in food webs.

Organophosphate esters and their metabolites in silver pomfret (Pampus argenteus) of the Vietnamese coastal areas: Spatial-temporal distribution and exposure risk

A large number of studies on organophosphate esters (tri-OPEs) in marine organisms have not assessed the simultaneous occurrence of tri-OPEs and their metabolites (di-OPEs) in these species. This research investigated the concentration and geographical distribution of 15 tri-OPEs and 7 di-OPEs in 172 samples of Pampus argenteus that were collected annually from 2021 to 2023 at three distinct locations along the Vietnamese coast. As a result, tri-OPEs and di-OPEs were detected in numerous fish samples, indicating their widespread spatial and temporal occurrence in marine fish and pointing out the importance of monitoring their levels. The tri-OPEs and di-OPEs ranged within 2.1-38.9 ng g-1 dry weight (dw) and 3.2-263.4 ng g-1 dw, respectively. The mean concentrations of tri-OPEs ranged from 0.4 (TIPrP) to 5.4 ng g-1 dw (TBOEP), with TBOEP and TEHP having the highest mean values. In addition, the profiles of tri-OPEs in fish exhibited a descending order: Σalkyl OPEs > ΣCl-alkyl OPEs > Σaryl OPEs. The di-OPEs, namely BEHP and DMP, had the highest mean levels, measuring 33.4 ng g-1 dw and 23.8 ng g-1 dw, respectively. Furthermore, there have been significant findings of strong positive correlations between di-OPEs and tri-OPE pairs (p < 0.05). It is worth noting that there is a noticeable difference in the composition of tri-OPEs between the North and other regions. Despite these findings, the presence of OPE-contaminated fish did not pose any health risks to Vietnam's coastal population.

Bioaccumulation and Potential Endocrine Disruption Risk of Legacy and Emerging Organophosphate Esters in Cetaceans from the Northern South China Sea

Despite the increasing health risks shown by the continuous detection of organophosphate esters (OPEs) in biota in recent years, information on the occurrence and potential risks of OPEs in marine mammals remains limited. This study conducted the first investigation into the body burdens and potential risks of 10 traditional OPEs (tOPEs) and five emerging OPEs (eOPEs) in 10 cetacean species (n = 84) from the northern South China Sea (NSCS) during 2005-2021. All OPEs, except for 2-ethylhexyl diphenyl phosphate (EHDPHP), were detected in these cetaceans, indicating their widespread occurrence in the NSCS. Although the levels of the ∑10tOPEs in humpback dolphins remained stable from 2005 to 2021, the concentrations of the ∑5eOPEs showed a significant increase, suggesting a growing demand for these new-generation OPEs in South China. Dolphins in proximity to urban regions generally exhibited higher OPE concentrations than those from rural areas, mirroring the environmental trends of OPEs occurring in this area. All OPE congeners, except for EHDPHP, in humpback dolphins exhibited a maternal transfer ratio >1, indicating that the dolphin placenta may not be an efficient barrier for OPEs. The observed significant correlations between levels of OPEs and hormones (triiodothyronine, thyroxine, and testosterone) in humpback dolphins indicated that OPE exposures might have endocrine disruption effects on the dolphin population.