Xiao-Jun Luo

Organophosphate flame retardants (PFRs) have increasingly substituted legacy brominated flame retardants, yet their bioaccumulation and trophic transfer across coupled aquatic–terrestrial food webs remain poorly understood. The present study investigated the occurrence, bioaccumulation, and biomagnification of 15 PFRs in abiotic (water, sediment, and soil) and biotic (vegetation, invertebrates, and vertebrates) compartments from a former e-waste recycling region in South China. Average ΣPFRs concentrations ranged from 2.64 to 23.2 ng/g wet weight (ww) in organisms, dominated by tris(2-chloroisopropyl) phosphate, triphenyl phosphate, tris-n-butyl phosphate, and tris(2-chloroethyl) phosphate. Most PFRs showed limited bioaccumulation potential, with bioaccumulation factors (BAFs) and biota-sediment/soil accumulation factors of 1.12–5426 L/kg and 0.00299–23.7, respectively. While ΣPFRs underwent biodilution across all four aquatic–terrestrial food chains, congener-specific biomagnification was observed. Significantly positive correlations were observed between log octanol–water partition coefficients (log K_ow) and log BAFs in aquatic species and terrestrial plants, while negative correlations appeared between log K_ow and biomagnification factors, indicating that the bioaccumulation of PFRs is co-driven by the moderate lipophilicity of congeners and efficient biotransformation in high-trophic-level predators. These findings highlight the divergent trophic transfer of PFRs across aquatic–terrestrial ecotones, providing key insights for ecological risk assessment in post-e-waste recycling environments.

Although Dehalogenimonas is as prevalent as Dehalococcoides across organohalide-contaminated habitats, its catalytic capacity and substrate profile toward diverse carbon skeletons and halogen substituents remain largely unexplored. Here, we systematically investigated the anaerobic biotransformation of six representative halogenated organic pollutants by a Dehalogenimonas-rich consortium (QY2-S1). Single-exposure assays revealed marked kinetic divergence spanning an order of magnitude, with 2,3-dibromopropyl-2,4,6-tribromophenyl ether (DPTE, 3.91 ± 0.34 d⁻¹) > β-1,2,5,6-tetrabromocyclooctane (β-TBCO, 2.35 ± 0.13 d⁻¹) > 2,2′,4,4′,5-pentabromodiphenyl ether (BDE 99, 1.31 ± 0.09 d⁻¹) > 1,1,1,3,10,11-hexachloroundecane (a short-chain chlorinated paraffin [SCCP] congener, 0.15 ± 0.01 d⁻¹) > 2,2′,3,3′,6,6′-hexachlorobiphenyl (PCB 136, 0.11 ± 0.01 d⁻¹), whereas tris(2-chloroethyl) phosphate (TCEP) remained untransformed. Transformation kinetics might be primarily governed by carbon–halogen bond dissociation energies and carbon skeleton geometry, with aliphatic and brominated compounds exhibiting faster transformation rates than aromatic and chlorinated analogues. Under binary co-exposures, competitive inhibition varied from reciprocal kinetic attenuation (in BDE 99 & β-TBCO and DPTE & β-TBCO pairs) to pronounced asymmetry (in PCB 136 & BDE 99 and PCB 136 & 1,1,1,3,10,11-hexachloroundecane pairs), whereas TCEP completely halted PCB 136 dechlorination. Product identification revealed that the Dehalogenimonas-rich consortium facilitated ortho-regioselective debromination of BDE 99, concurrent aromatic debromination and side-chain dihalo-elimination/dehydrobromination of DPTE, reductive dechlorination/dehydrochlorination of the SCCPs, and dibromo-elimination coupled with epoxidation of β-TBCO. These findings provide critical insights into the environmental fate and bioremediation potential of organohalide mixtures in anoxic environments.

To assess the contamination levels of organophosphate diesters (di-OPEs) in large-scale urban water bodies, this study investigated four di-OPEs (bis(2-chloroethyl) phosphate [BCEP], bis(1-chloro-2-propyl) phosphate [BCIPP], bis(1,3-dichloro-2-propyl) phosphate [BDCIPP], and bis(2-ethylhexyl) phosphate [BEHP]) in surface sediments from 173 black-odorous urban rivers across China. Di-OPEs were ubiquitously detected (not detected to 484 ng/g dry weight), dominated by BEHP (58.8% ± 24.5%) and BCIPP (32.3% ± 25.5%). Spatially, total di-OPEs followed a regional trend of Northeast ≈ East > Central ≈ West China, which correlated significantly with urban gross domestic product and wastewater treatment capacity, implying industrial inputs. High molar concentration ratios of di-OPEs to their parent tri-OPEs (medians: 0.74–3.26) suggested significant tri-OPE degradation contributions. Correlation analyses suggested that chemical hydrolysis and microbial activity, associated with a high abundance of putative OPE-degrading bacteria, may synergistically regulate the degradation sources of di-OPEs. Screening-level acute risk quotients exceeded chronic values by 1–2 orders of magnitude, with BEHP posing widespread high acute risks (risk quotient >1.00) at 96.0% of sites. These benchmark findings emphasize the necessity of regional source control and pollutant management frameworks to secure urban aquatic safety.

This study investigated the sex-specific toxicokinetics of per- and polyfluoroalkyl substances (PFASs) in Thai tiger frogs via dermal and dietary exposure. The lower depuration rate constant (kd) of PFASs in the dermal group than in the dietary group results in a higher assimilation efficiency (11% vs 3.7% for males and 21% vs 4.4% for females) in the former. Female frogs exhibited higher kd than male frogs (0.19 vs 0.057 per day for perfluorocarboxylic acid (PFCA) and 0.20 vs 0.062 per day for perfluorosulfonic acid (PFSA), especially for long-chain PFCA and PFSA, but these differences were attenuated in the dermal group (0.048 vs 0.035 per day and 0.041 vs 0.041 per day). Generally, dietary exposure resulted in higher serum PFAS burdens in the exposure phase, whereas dermal exposure led to direct diffusion into multiple tissues with higher hepatic burdens. During depuration, hibernation-induced translocation of PFASs from eggs to the liver was more pronounced in the dietary group than in the dermal group. We hypothesize that bypassing hepatic and intestinal first-pass effects provides a plausible mechanistic explanation. This may potentially decrease PFAS binding to intestinal and hepatic transport proteins, possibly leading to slower transport-related activities, especially for female frogs. These findings demonstrated that exposure routes significantly shape PFAS toxicokinetics and the sex-specific accumulation in frogs. However, the precise molecular mechanisms merit further in-depth studies.

Ubiquitous organophosphate flame retardants (PFRs) have raised profound ecotoxicological concerns, yet their effects on insects at lower trophic levels remain poorly understood. This study systematically evaluated the multifaceted impacts of PFR exposure on growth, detoxification, hormonal homeostasis, and metabolic perturbation in silkworms (Bombyx mori). Our results revealed severe dose-dependent PFR toxicity in silkworms: larval mortality increased with dose, while growth and development were inhibited, as evidenced by reduced nutritional efficiency, delayed cocooning, decreased cocoon shell weight, and lower pupation and eclosion rates. Medium and high doses also reduced the egg production of female moth, indicating population-level risks. Silkworms exhibited distinct stage- and sex-specific detoxification and hormonal responses to PFR exposure. Larvae showed hormetic biphasic changes in cytochrome P450, carboxylesterase, and glutathione S-transferase activities, while pupae and adults exhibited divergent sex-specific responses, with females generally showing more pronounced dose-dependent adjustments than males. PFRs disrupted juvenile hormone (JH) and 20-hydroxyecdysone (20E) homeostasis, with larval hormone titers declining with dose, pupal hormone levels remaining relatively stable, and medium/high doses in adults elevating male JH but suppressing female 20E levels. Metabolomics analysis revealed extensive perturbations in lipid, amino acid, energy, and steroid hormone metabolism, with phosphatidylcholine (PC(15:0/22:2)), phosphatidic acid (PA(20:5/14:0)), stearoylcarnitine, (R)-2-hydroxystearic acid, 7α-hydroxycholesterol, β-methylmalyl-CoA, and Hydantoin-5-propionic acid identified as key toxicity mediators. Correlation analyses uncovered synergistic regulatory mechanisms among metabolic perturbation, detoxification defense, and endocrine systems. These findings advance PFR ecological risk assessment for Lepidoptera, emphasizing the critical need for life cycle- and gender-specific risk evaluations.