Application of enantiomeric fractions in environmental forensics: Uncertainties and inconsistencies

Enantioselective Toxicity of Tetramethrin to Different Developmental Stages of Zebrafish (Danio rerio)

Chiral pesticides exhibit enantioselective differences in processes such as biological absorption, metabolism, and toxic effects. Organisms have different physiological characteristics at different developmental stages. Therefore, conducting enantiomeric toxicity studies at different developmental stages of organisms can help deepen the understanding of the ecological effects of chiral pesticides. This study focused on trans-tetramethrin (Tet) and investigated the enantioselectivity in bioconcentration, developmental toxicity, estrogenic effects, and immunotoxicity of Tet's racemate ((±)-Tet) and its two enantiomers ((+)-Tet and (-)-Tet) in three developmental stages of zebrafish: embryos, yolk sac larvae, and juveniles. The results showed that Tet exhibited different enantioselectivity in lethal, bioconcentration, and teratogenic effects on zebrafish at different developmental stages. The LC50 value was (+)-Tet > (±)-Tet > (-)-Tet, with embryos being the most sensitive, followed by juveniles and yolk sac larvae. The enantioselective bioconcentration was (±)-Tet > (+)-Tet > (-)-Tet, and the bioconcentration effect was greater in embryos than that in yolk sac larvae and juveniles. Developmental toxicity indicated that (+)-Tet and (±)-Tet had higher teratogenic effects on yolk sac larvae than on embryos. Tet exhibited different enantioselective effects on the expression of zebrafish estrogen-related genes and innate immune-related genes at different developmental stages. These results will contribute to a more comprehensive assessment of the aquatic toxicity and environmental risks of chiral pesticides.

Hexabromocyclododecanes in surface soil-maize system around Baiyangdian Lake in North China: Distribution, enantiomer-specific accumulation, transport, temporal trend and dietary risk

This study investigated the occurrence of hexabromocyclododecanes (HBCDs) in soil-maize system around Baiyangdian Lake. The total concentration of ΣHBCDs was in the order of industrial area > residential area > marginal area > Fuhe River estuary in soil. γ-HBCD was predominated in soils, roots and stems, while α-HBCD was the main diastereoisomer in leaves and kernels. Concentration of ΣHBCDs and three diastereoisomer concentrations in soils were significantly reduced and remained low level from 2018 to 2019. Selectivity enrichment of (+)α- and (-)γ-HBCD was found in soils, roots, stems and leaves, whereas only (+)β-HBCD dominated in stems. Most of the total root bioaccumulation factors (ΣRCFs) were less than 1.0, but no significant correlation was showed between translocation factors (TFs) and log K_ow. RCFs and TFs of enantiomers suggested (-)β- and (-)γ-HBCD were easily translocated from soil to roots, while (+)α-, (-)β- and (-)γ-HBCD tended to translocate from stems to leaves. Estimated daily intake (EDI) and of ΣHBCDs, diastereoisomers and enantiomers were all lower than the threshold value, while the Calculated margins of exposure (MOE) were well above the threshold value, which demonstrate the safe consumption of Maize around Baiyangdian Lake.

Emerging environmental contaminants: A global perspective on policies and regulations

Emerging contaminants include many synthetic or natural substances, such as pharmaceuticals and personal care products, hormones, and flame retardants that are not often controlled or monitored in the environment. The consumption or use of these substances is on an ever-rising trend, which dangerously increases their prevalence in practically all environmental matrices. These contaminants are present in low environmental concentrations and cause severe effects on human health and the biota. The present review analyzed 2012-2022 years papers via PubChem, science direct, National Center for Biotechnology Information, web of science on the legislations and policies of emerging contaminants globally. A state-of-the-art review of several studies in the literature focus on examining and evaluating the emerging contaminants and the frameworks adopted by developed and developing countries to combat the release of emerging contaminants and form footprints towards water sustainability which includes water availability, usage patterns, generation and pollution management, the health of aquatic systems, and societal vulnerability. The paper aims to provide a comprehensive view of current global policies and framework regarding evaluating and assessing the chemicals, in light of being a threat to the environment and biota. The review also highlights the future global prospects, including current governmental activities and emerging contaminant policy measures. The review concludes with suggestions and way forward to control the inventory and disposal of emerging contaminants in the environment.

Adsorption and leaching of β-blockers in fluvo-aquic and black soil: Behavior characteristic and enantiomer selectivity

β-blockers are widely used chiral pharmaceuticals to treat hypertension and cardiovascular diseases, which are ubiquitously detected in the water-soil environment. However, little is known about their biogeochemical behaviors and enantiomer selectivity during soil migration and transformation. In this study, the adsorption and leaching behaviors of β-blockers in fluvo-aquic soil and black soil were investigated. The adsorption of β-blockers was fit well by the Freundlich adsorption isotherm (R² > 0.913) and the adsorption affinity of β-blockers decreased in the following order: propranolol (logarithm of Freundlich adsorption coefficient log K_f = 1.46-2.55) > atenolol (log K_f = 0.53-1.04) > sotalol (log K_f = 0.32-1.01). An increase in ionic strength and dissolved organic matter (DOM) inhibited their soil adsorption. Ionic change is the main driving force for adsorption. Besides, hydrophobic partitioning and hydrogen bonding played key roles in the adsorption of propranolol and atenolol, respectively. The leaching behaviors of β-blockers are related to their hydrophobicity. An increase in ionic strength enhanced the migration of β-blockers to deeper soil layers, and the presence of DOM accelerated the migration of sotalol and propranolol. The migration potential of β-blockers in black soil is lower than that in fluvo-aquic soil, which could be ascribed to the higher organic matter content and strong ion exchange ability of black soil. Further, more significant enantiomer selectivity of β-blockers was found in black soil (e.g. enantiomer fraction of atenolol = 0.61) than in fluvo-aquic soil (e.g. enantiomer fraction of atenolol = 0.53) during the leaching process. The microbial activity might influence the enantiomer selectivity of studied β-blockers during soil leaching.

COVID-19 drugs in aquatic systems: a review

The outbreak of the human coronavirus disease 2019 (COVID-19) has induced an unprecedented increase in the use of several old and repurposed therapeutic drugs such as veterinary medicines, e.g. ivermectin, nonsteroidal anti-inflammatory drugs, protein and peptide therapeutics, disease-modifying anti-rheumatic drugs and antimalarial drugs, antiretrovirals, analgesics, and supporting agents, e.g. azithromycin and corticosteroids. Excretion of drugs and their metabolites in stools and urine release these drugs into wastewater, and ultimately into surface waters and groundwater systems. Here, we review the sources, behaviour, environmental fate, risks, and remediation of those drugs. We discuss drug transformation in aquatic environments and in wastewater treatment systems. Degradation mechanisms and metabolite toxicity are poorly known. Potential risks include endocrine disruption, acute and chronic toxicity, disruption of ecosystem functions and trophic interactions in aquatic organisms, and the emergence of antimicrobial resistance.

Wastewater analysis of psychoactive drugs: Non-enantioselective vs enantioselective methods for estimation of consumption

The consumption of licit and illicit psychoactive drugs (PAD) is ubiquitous in all communities and a serious public health problem. Measuring drug consumption is difficult but essential for health-care professionals, risk assessment and policymakers. Different sources of information have been used for a comprehensive analysis of drug consumption. Among them, Wastewater based epidemiology (WBE) emerged as an essential and complementary methodology for estimating licit and illicit drugs consumption. This methodology can be used for quantification of unchanged drugs or their human-specific metabolites in wastewater for estimation of consumption or screening of new PAD. Although some limitations are still being pointed out (e.g., estimation of the population size, use of suitable biomarkers or pharmacokinetics studies), the non-invasive and potential for monitoring real-time data on geographical and temporal trends in drug use have been showing its capacity as a routine and complementary tool. Chromatographic methods, both non-enantioselective and enantioselective are the analytical tools used for quantification of PAD in wastewaters and further estimation of consumption. Therefore, this manuscript aims to summarize and critically discuss the works used for wastewater analysis of PAD based on WBE using non-enantioselective and enantioselective methods for estimation of consumption. Non-enantioselective methods are among the most reported including for chiral PAD. Nevertheless, a trend has been seen towards the development of enantioselective methods as most PAD are chiral and determination of the enantiomeric fraction can provide additional information (e.g., distinction between consumption or direct disposal, or manufacture processes) and fulfill some WBE gaps.

Stereoselective environmental fate of fosthiazate in soil and water-sediment microcosms

The stereoselective fates of chiral pesticides in the environment has been reported in many studies. However, there is little data focused on the fate of chiral fosthiazate in the soil and aquatic ecosystems at chiral view. This study investigated the stereoselective fate of fosthiazate in the soil and aquatic ecosystems using ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) and liquid chromatography tandem time-of-flight mass spectrometry (LC-TOF/MS/MS). Significant stereoselective degradation among four fosthiazate stereoisomers were found in both greenhouse soil and water-sediment microcosms. In greenhouse soil, (1R,3S)-fosthiazate degraded faster than other three stereoisomers with the half-life of 2.7 d. The fosthiazate stereisomers in the seawater-sediment microcosm degraded more rapidly than in the river water-sediment microcosm. However, (1S,3R)-fosthiazate and (1S,3S)-fosthiazate possessed shorter degradation half-lives than their enantiomers in both microcosms, with the half-lives ranging from 3.4 d to 15.8 d. Ten degradation products were identified in the water-sediment microcosms, and, six of them were reported for the first time. Oxidation and hydrolysis were confirmed as the main degradation pathways of fosthiazate in the water-sediment microcosms. Our results revealed that the (1R,3S)-fosthiazate and (1R,3R)-fosthiazate may cause more serious ecotoxicity due to the longer half-lives than the other two stereoisomers in environment.