Application of enantiomeric fractions in environmental forensics: Uncertainties and inconsistencies.

The assumption that only biological processes are enantioselective introduces challenges in the reliability of enantioselective analysis as a tool for discriminating biotic and abiotic processes in the environmental fate of chiral pollutants. Enantioselectivity does not depend on the nature of the fate process a chiral contaminant undergoes but on the interaction of the chiral contaminant with homochirality inducing external agents (e.g. chiral molecules, macromolecules or surfaces such as enzymes, blood plasma, proteins, chiral co-pollutants, humic acid and soil organominerals). The environmental behavior of a chiral contaminant is difficult to anticipate because the interactions between the chiral contaminants and the homochirality inducing external agents is often complex and strongly influenced by local environment conditions such as pH, redox conditions, organic carbon, organic nitrogen, humic acid, and redox conditions. Furthermore, the use of enantioselective analysis in environmental forensics depend on the adequate separation and accurate identification and quantification of the enantiomers of the chiral contaminant. Matrix effects, instrument effects, inadequate enantioselective separation, and poor quantification techniques introduce uncertainties in the determination of enantiomeric composition. Here we present the weaknesses of this assumption and recommend using enantiomeric fractions as chemical markers of biotransformation with caution. We recommend using stable isotopes, including abiotic controls to determine if enantioselective sorption occurs, and determining stability of enantiomers in solvent or at elevated temperatures to account for confounding factors arising from matrix effects, enantioselective abiotic processes, and enantiomerization due solvent and thermal lability of the chiral analyte, respectively to maintain the integrity of the utility of enantiomeric composition changes as an environmental forensics tool.

Determination of the stereoisomeric distribution of R-(-)- and S-(+)-methamphetamine in Thai pills in the legal context of "not inconsiderable quantities".

In Germany, the severity of a narcotic offence is determined based on the classification into different categories of quantity. Recently, an amendment to the Narcotics Law regarding the "not inconsiderable quantities" was introduced. The new limits for methamphetamine are derived from the varying potency of the respective enantiomers. Switzerland, however, does not practice this distinction and there is only one limit quantity, without considering the isomeric structure. To examine whether this single value is still contemporary, 26 Thai pill samples from the years 2000, 2001, 2007, 2009 and 2017 were analyzed by HPLC-MS/MS and GC-MS. Both methods resulted in similar stereoisomeric distributions: the pills mainly consist of the more potent S-(+)-methamphetamine, some even being enantiopure. Others show enantiomeric mixtures of R-(-)-/S-(+)-methamphetamine, but rarely in an equimolar ratio. There even was one sample, where mainly the less potent R-(-)-methamphetamine was detected. In conclusion, the analyses revealed that the single value for a "not inconsiderable quantity" in Switzerland seems outdated. Most of the sized pills showed a much higher concentration of the more potent S-(+)-methamphetamine. The risks related to taking such a pill are much higher and therefore the limit quantity should be adapted to the potency of the respective enantiomers.

Spatial redistribution and enantiomeric signatures of hexachlorocyclohexanes in Chinese forest soils: Implications to environmental behavior and influencing factors.

Hexachlorocyclohexanes (HCHs) are a group of highly persistent pesticides. The concentrations of HCHs and the enantiomeric fractions of α-HCH in the O- and A-horizons from 30 mountains across China were analyzed in this study. The concentrations of total HCHs ranged from 0.061 to 46.9 ng/g (mean 2.12 ng/g) and 0.046 to 16.1 ng/g (mean 0.792 ng/g) in the O- and A-horizons, respectively. The HCH residues were mainly derived from the historical applications of technical HCH and lindane. Higher concentrations of HCHs were typically found in northern China, and no significant correlations were found between historical technical HCH usage and HCH isomer concentrations in either the O- or A-horizons (p > 0.05). Conversely, the concentrations of HCH isomers were significantly correlated with the environmental parameters (temperature and precipitation), thus indicating a typical secondary distribution pattern. Some HCH isomers tended to be transported northward under the long-term effect of monsoon. Chiral α-HCH was non-racemic in soils and showed preferential degradation of (-) α-HCH in both the O- and A-horizons. The transformation from γ-HCH to α-HCH might alter the enantiomeric signatures of α-HCH in soils. Moreover, the deviation from racemic of α-HCH was positively correlated with the C/N ratio in the A-horizon (p < 0.01), thus suggesting that the C/N ratio could alter the microbial activity and significantly affect the enantioselective degradation extent of α-HCH in soils.

Uptake and Enantiomeric Selectivity of ß-Blockers in Lettuce (Lactuca sativa L.) and Tomato (Lycopersicon esculentum M.) in Soil-Pot Culture.

The uptake and translocation of ß-blockers in lettuce (Lactuca sativa L.) and tomato (Lycopersicon esculentum M.) were investigated by carrying out a 70-day soil-pot cultivation. The root uptake parameters of ß-blockers in lettuce decreased in the order of atenolol (ATE) > sotalol (SOT) > propranolol (PRO) with root bioconcentration factors (BCFsroot/soil) of 0.158, 0.136, and 0.096, respectively, which were positively correlated with their water solubility. The BCFroot/soil of ß-blockers in tomato was higher than those in lettuce. ATE and PRO were prone to migrate to the aerial parts of tomato with translocation factors of 3.31 and 4.11, respectively. In tomato fruits, the enantiomeric profile of PRO and ATE shifted to that dominated by the more toxic enantiomer, i.e., (S)-PRO and (R)-ATE. The enantiomeric selectivity of ß-blockers in the edible parts of lettuce and tomato indicated the potential ecotoxicity of these pharmaceuticals for plants and the human exposure risk via vegetable intake.

Enantiomer fraction evaluation of the four stereoisomers of second-generation anticoagulant rodenticides in biological matrices with polysaccharide-based chiral selectors and liquid chromatography tandem mass spectrometry.

Numerous cases of wildlife exposure to five second-generation anticoagulant rodenticides have been reported worldwide, and residues of these chiral pesticides in biological matrices are still quantified by achiral liquid chromatography methods. However, they are a mixture of cis- and trans-diastereomers, thus a mixture of four stereoisomers. Their persistence must be evaluated in a differentiated way in the food chain of concerned predator species in order to reduce the environmental impact. This article presents an evaluation of the chiral selectivity of five polysaccharide-based chiral selectors for the four stereoisomers of bromadiolone, difenacoum, brodifacoum, flocoumafen and difethialone. Different chromatographic parameters, influencing the chiral separation, such as organic modifier (acetonitrile, methanol), percentage of formic acid and water content in the mobile phase are systematically tested for all columns. It was shown that little amount of water added to the acetonitrile mobile phase may influence the retention behaviors between reversed phase and HILIC-like modes, and consequently the enantiomer elution order of the four stereoisomers. On the contrary, reversed phase is always the observed mode for the methanol water mobile phase. A suitable combination of all these parameters is presented for each second-generation anticoagulant rodenticide with a description of the enantioresolution, the enantiomer elution order and the retention times of the respective stereoisomers. A method is validated for all stereoisomers of each second-generation anticoagulant rodenticide with chicken liver and according to an official bioanalytical guideline. As an example, the enantiomer fraction is evaluated in the liver of a raptor species (rodent predator) exposed to bromadiolone and difenacoum. The results showed that only one enantiomer of trans-bromadiolone and one enantiomer of cis-difenacoum is present in hepatic residues, although all four stereoisomers are present in bromadiolone and difenacoum rodenticide baits.

Supercritical fluid chromatography-mass spectrometric determination of chiral fungicides in viticulture-related samples.

Supercritical fluid chromatography (SFC), combined with mass spectrometry (MS), was employed for the determination of five chiral fungicides, from two different chemical families (acylalanine and triazol) in wine and vineyard soils. The effect of different SFC parameters (stationary phase, chiral selector, mobile phase modifier and additive) in the resolution between enantiomers and in the efficiency of compounds ionization at the electrospray source (ESI) was thorougly described. Under final working conditions, chiral separations of selected fungicides were achieved using two different SFC-MS methods, with an analysis time of 10 min and resolution factors from 1.05 to 2.45 between enantiomers. In combination with solid-phase extraction and pressurized liquid extraction, they permitted the enantiomeric determination of target compounds in wine and vineyard soils with limits of quantification in the low ppb range (between 0.5 and 2.5 ng mL-1, and from 1.3 to 6.5 ng g-1, for wine and soil, respectively), and overall recoveries above 80%, calculated using solvent-based standards. For azolic fungicides (tebuconazole, myclobutanil and penconazole) soil dissipation and transfer from vines to wines were non-enantioselective processes. Data obtained for acylalanine compounds confirmed the application of metalaxyl (MET) to vines as racemate and as the R-enantiomer. The enantiomeric fractions (MET-S/(MET-S+MET-R)) of this fungicide in vineyard soils varied from 0.01 to 0.96; moreover, laboratory degradation experiments showed that the relative dissipation rates of MET enantiomers varied depending on the type of soil.

Chiral inversion of 2-arylpropionoic acid (2-APA) enantiomers during simulated biological wastewater treatment.

This study examined the removal and enantio­specific fate of a suite of eleven chiral 2-arylpropionic acids (2-APAs) during biological wastewater treatment simulated in a laboratory-scale membrane bioreactor (MBR). Using pure (R)- and (S)- enantiomers in the MBR influent, chiral inversion was determined through the increase in the concentration of the non-dominant enantiomer and changes in the enantiomeric fraction (EF) between the two enantiomers during the treatment process. Effective (>90%) and similar removal rates between (R)- and (S)- enantiomers were confirmed for eight 2-APAs. In this study, 2-APAs exhibited diverse and distinctive chiral inversion behaviours: two 2-APAs showed (R→S) unidirectional inversion, three 2-APAs showed (S→R) unidirectional inversion, and six 2-APAs showed bidirectional inversion. This is the first study to report chiral inversion behaviours of a comprehensive suite of 2-APAs with a variety of functional groups substituted onto the aryl ring. A decrease in effluent EF over time was observed for two 2-APAs. This study shows that chiral inversion of 2-APAs varies significantly from compound to compound, despite the high similarity in their chemical structures.

Levels and enantiomeric signatures of organochlorine pesticides in Chinese forest soils: Implications for sources and environmental behavior.

We investigated the levels and distributions of organochlorine pesticides (OCPs) in 159 background soil samples collected from 30 forested mountain sites across China. The sum of DDT was the most abundant OCP, with the concentrations of 0.197-207 ng/g and 0.033-122 ng/g in the O-horizon and A-horizon, respectively. High concentrations of OCPs usually occur near agricultural regions or high consumption areas. The spatial distribution was mainly influenced by the emission sources and soil total organic contents (TOC). The chiral compounds were generally nonracemic in the soils and showed preferential degradation of (-) o,p'- dichlorodiphenyltrichloroethane, (+) trans-chlordane, and (-) cis-chlordane in both the O- and A-horizons. The enantiomeric fraction (EF) distributions of chiral OCPs displayed no differences across the forest sites in the O-horizon or the A-horizon. Comparing the deviation of EFs from racemic (DEVrac = absolute value of 0.500 - EF) with environmental parameters, we found that DEVrac of cis-chlordane demonstrated a strong positive correlation with TOC (p < 0.05) and the C/N ratio (p < 0.01). This relationship suggests that these factors could affect the microbial activity and significantly impact the extent of enantioselective degradation of chiral compounds in the soils. Fresh and historical applications of DDT and historical chlordane and endosulfan uses may be prominent sources of OCP accumulation in Chinese forest soils.

Microbial transformation of chiral organohalides: Distribution, microorganisms and mechanisms.

Chiral organohalides including dichlorodiphenyltrichloroethane (DDT), Hexabromocyclododecane (HBCD) and polychlorinated biphenyls (PCBs) raise a significant concern in the environmental occurrence, fate and ecotoxicology due to their enantioselective biological effects. This review provides a state-of-the-art overview on enantioselective microbial transformation of the chiral organohalides. We firstly summarized worldwide field assessments of chiral organohalides in a variety of environmental matrices, which suggested the pivotal role of microorganisms in enantioselective transformation of chiral organohalides. Then, laboratory studies provided experimental evidences to further link enantioselective attenuation of chiral organohalides to specific functional microorganisms and enzymes, revealing mechanistic insights into the enantioselective microbial transformation processes. Particularly, a few amino acid residues in the functional enzymes could play a key role in mediating the enantioselectivity at the molecular level. Finally, major challenges and further developments toward an in-depth understanding of the enantioselective microbial transformation of chiral organohalides are identified and discussed.

Dual enantioselective LC-MS/MS method to analyse chiral drugs in surface water: Monitoring in Douro River estuary.

This work presents the development of an enantioselective method to quantify chiral drugs (CDs) in surface water and its application in the Douro River estuary monitoring. Different classes of CDs were targeted, including 23 compounds, namely beta-blockers, antidepressants, one beta2-adrenergic agonist, non-steroidal anti-inflammatory drugs, stimulants, and some illicit drugs as cocaine (COC) and its metabolites, and amphetamines. The analytical method was based on an innovative application of solid phase extraction (SPE), followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using a triple quadrupole analyzer. The ground-breaking approach of SPE consists in the use of Oasis® MCX cartridges to pre-concentrate 500 mL of water samples, allowing the simultaneous extraction of acidic, basic and neutral analytes, rather than the conventional recovery of basic compounds only. Two chiral columns were used for enantiomeric separation in reverse elution mode, a Chirobiotic™V and a Pirkle type Whelk-O®1, for basic and acidic compounds, respectively. The method validation demonstrated good linearity (r2 > 0.99), selectivity and sensitivity, with method detection limits between 0.01 and 2.66 ng L-1 and method quantification limits between 0.02 and 5.71 ng L-1. The developed method was successfully applied to monitor daily variations along one week in surface waters collected in 5 locations of the Douro River estuary. Tramadol (TRM) and its metabolite N-desmethyltramadol (NDT), presented high concentrations near the affluent of a tributary river, while the second eluted enantiomer of O-desmethyltramadol (ODT) was found at high concentrations at the mouth of the Douro River. The metabolite NDT was quantified at higher concentrations than TRM. Venlafaxine (VNF) was found at high concentrations near the affluent of the same tributary river, but its metabolite, O-desmethylvenlafaxine (ODV), was found at concentrations 3 times higher. COC was found every day at all sampling points along the estuary, with slight variations.

Transplacental transfer of organochlorine pesticides: Concentration ratio and chiral properties.

Currently, there is limited information about the mechanism of the human transplacental transfer for organochlorine pesticides (OCPs). This study aimed to evaluate the transplacental transfer of OCPs to better understand the influencing factors of exposure and transplacental efficiency. The study involved quantitative determination of OCPs and the enantiomer fraction (EF) of chiral OCPs in pregnant women from Wuhan, China. The results indicate that the exposure levels of OCPs varied in the order: maternal serum > cord serum > placenta. Chiral contaminants, such as α-HCH, o,p'-DDD and o,p'-DDT, were non-racemic in the three biological matrices, wherein EFα-HCH < 0.5, EFo,p'-DDD < 0.5, EFo,p'-DDT > 0.5. For HCHs, the concentration ratio between cord serum and maternal serum (Rcm) <1, while for DDXs, the Rcm ≈ 1, indicating that the transport efficiency of different pollutants is related to the physicochemical properties. These results showed that placenta seems to be a more efficient barrier for ß-HCH than for p,p'-DDE. The concentration ratios across placenta significantly lower than 1 and the enantiomeric selective transfer imply that some OCPs may have more complicated maternal-fetus transfer mechanisms, involving both simple diffusion and active transport. To the best of our knowledge, this is the first study to investigate the transfer of OCPs and their enantiomer fractions across placenta. These findings could expand the database of chemical exposure in biological matrices and improve the understanding of the mechanisms of transplacental transfer of OCPs.

Enantiomeric ratios: Why so many notations?

The correct quantification of enantiomers is pivotal in a variety of fields, such as pharmacokinetic studies, enantioselective syntheses, chemical characterization of natural products, authentication of fragrance and food, biodegradation behavior, accurate evaluation of environmental risk, and it can also provide information for sentencing guidance in forensic field. Enantioselective chromatography is the first choice to assess the composition of an enantiomeric mixture. Different notations have been used to express the measured enantiomeric ratios, which compromise the results and represent a challenge for data comparison. This manuscript critically discusses the currently used notations and exemplifies with applications in different fields indicating the advantages and disadvantages of one of the adopted systems. In order to simplify the notations, the use of enantiomeric ratio (e.r.%) as standardization for nonchiroptical methods is proposed.

Occurrence, elimination, enantiomeric distribution and intra-day variations of chiral pharmaceuticals in major wastewater treatment plants in Beijing, China.

The occurrence, eliminations, enantiomeric distribution and intra-day variations of five chiral pharmaceuticals (three beta-blockers and two antidepressants) were investigated in eight major WWTPs in Beijing, China. The results revealed that metoprolol (MTP) and venlafaxine (VFX) were of the highest concentrations among the five determined pharmaceuticals with mean concentrations of 803 ng L-1 and 408 ng L-1, respectively in influents, and 354 ng L-1 and 165 ng L-1 in effluents, respectively. Their removal efficiencies, intra-day concentration changes and enantiomeric profiles during wastewater treatment were further analyzed. Loads of these two chiral pharmaceuticals were also studied to reveal drug use pattern. A/A/O+MBR (anaerobic/anoxic/oxic + membrane bio-reactor) followed by joint disinfection treatment process exhibited the high removal efficiencies. No or weak enantioselectivity was observed in most WWTPs. However, obvious enantiomeric fraction (EF) changing of MTP was observed in WWTP3 employing A/A/O+MBR. Intra-day concentration fluctuations of MTP were smaller than VFX. A quick response to sudden rise influent concentration of MTP was observed in WWTP1 effluent but EF response lagged behind. Similar bihourly EF variations in influents and effluents were also observed in most WWTPs for MTP and VFX in consideration of hydraulic residence time (HRT).

Assessing the use of sand, peat soil, and pine bark for the attenuation of polar pesticides from agricultural run-off: a bench-scale column experiment.

Biofilters have been shown to be efficient for removing pollutants from different water effluents, but little information is available about their capacity to remove highly polar pesticides from agricultural run-off waters. In this study, we assess the capacity of three different biofilter-supporting materials (sand, peat soil, and pine bark) to remove five phenoxyacid herbicides (mecoprop, dicamba, MCPA, dichlorprop and 2,4-D) and five non-ionic pesticides (atrazine, simazine, fenitrotion, diazinon, and alachlor) from real agricultural run-off waters. The experimental design included three columns 120 cm in length and 15 cm in diameter, each filled with 100 cm of one of the selected supporting materials. After 30 days of acclimation, the columns were fed with agricultural run-off water spiked at 10 µg L-1 with each of the studied pesticides for 20 days at a hydraulic loading rate (HLR) of 0.32 m day-1. The results show that the sand filter was the best supporting material for removing phenoxyacid herbicides (77% on average), whereas peat soil and pine bark were best for removing non-ionic pesticides (72% on average). The attenuation of mecoprop and dichlorprop correlated negatively with the enantiomeric fraction. Therefore, this study shows that the use of waste-to-product materials in biofilter systems is a good solution for removing pollutants from agricultural run-off waters.

Magnetic solid-phase extraction based on magnetic multiwalled carbon nanotubes for the simultaneous enantiomeric analysis of five ß-blockers in the environmental samples by chiral liquid chromatography coupled with tandem mass spectrometry.

In this work, the magnetic multiwalled carbon nanotubes (Mag-MWCNTs) were prepared by self-assembly method and characterized by scanning electron microscopy, X-ray powder diffraction, energy dispersive X-ray and vibrating sample magnetometer. Then, these synthetic Mag-MWCNTs were used as sorbents to extract five ß-blockers (atenolol, metoprolol, esmolol, pindolol and arotinolol) by magnetic solid-phase extraction. The target analytes adsorbed on Mag-MWCNTs were eluted and determined on a chiral α-acid glycoprotein column coupled with a triple quadrupole mass spectrometry. Eventually, the proposed method was applied to the analysis of the enantiomeric composition of the studied ß-blockers in three environmental samples, including river water, influent wastewater and effluent wastewater. Method detection and quantification limits for all enantiomers were in the range of 0.50-1.45 and 1.63-3.75ng/L, respectively. Satisfactory recovery (82.9-95.6%), good intra-day precision (RSD 0.4-10.4%) and inter-day precision (RSD 2.9-7.4%) were also obtained. With numerous advantages such as simplicity of operation, rapidity and high enrichment factor, the newly developed method has potential to assess the enantioselectivity of chiral drugs in ecotoxicity and biodegradation processes, which is also a new expanded application of Mag-MWCNTs in the environmental analysis.

Hens can ingest extruded polystyrene in rearing buildings and lay eggs contaminated with hexabromocyclododecane.

The overall concentration of hexabromocyclododecane (HBCDD) in eggs is low although abnormally high concentrations exceeding 3000 ng g-1 lw have been reported. In order to test whether these contaminations may originate from the ingestion of insulating materials in rearing buildings, a group of 55 hens raised in a collective cage was provided with a 64-g piece of extruded polystyrene (XPS, 2.59% HBCDD of which 75, 15 and 10% as α-, ß- and γ-HBCDD, respectively). Hens entirely consumed the piece within 3 days, leading to a mean daily exposure of 4.7 mg HBCDD per kg body weight. Whole egg HBCDD concentration reached a maximum of 1037 ng HBCDD g-1 fresh weight (fw), recorded 2 days after the piece had disappeared, and decreased down to 86 ng g-1 fw within the 19 following days. In all these samples, HBCDD was made of 98.7 ± 0.7 and 1.3 ± 0.6% α- and ß-HBCDD, respectively, and 0.1% γ-HBCDD when quantified; it was enriched in (-)α- and (+)ß-HBCDD with enantiomeric fractions of 0.438 ± 0.009 and 0.579 ± 0.030, respectively. HBCDD was quantified in all the individual eggs collected the last day of experiment at concentrations ranging between 0.47 and 1361 ng g-1 fw, according to a lognormal distribution. The ingestion of XPS in degraded rearing buildings is thus a plausible cause of on-farm egg contamination by HBCDD which should be strictly avoided.

Enantioselective uptake, translocation and degradation of the chiral pesticides tebuconazole and imazalil by Phragmites australis.

Phytoremediation of realistic environmental concentrations (10 µg L-1) of the chiral pesticides tebuconazole and imazalil by Phragmites australis was investigated. This study focussed on removal dynamics, enantioselective mechanisms and transformation products (TPs) in both hydroponic growth solutions and plant tissues. For the first time, we documented uptake, translocation and metabolisation of these pesticides inside wetland plants, using enantioselective analysis. Tebuconazole and imazalil removal efficiencies from water reached 96.1% and 99.8%, respectively, by the end of the experiment (day 24). Removal from the solutions could be described by first-order removal kinetics with removal rate constants of 0.14 d-1 for tebuconazole and 0.31 d-1 for imazalil. Removal of the pesticides from the hydroponic solution, plant uptake, within plant translocation and degradation occurred simultaneously. Tebuconazole and imazalil concentrations inside Phragmites peaked at day 10 and 5d, respectively, and decreased thereafter. TPs of tebuconazole i.e., (5-(4-Chlorophenyl)-2,2-dimethyl-3-(1H-1,2,4-triazol-1-ylmethyl)-1,3-pentanediol and 5-(3-((1H-1,2,4-Triazol-1-yl)methyl)-3-hydroxy-4,4-dimethylpentyl)-2-chlorophenol) were quantified in solution, while the imazalil TPs (α-(2,4-Dichlorophenyl)-1H-imidazole-1-ethanol and 3-[1-(2,4-Dichlorophenyl)-2-(1H-imidazol-1-yl)ethoxy]-1,2-propanediol) were quantified in both solution and plant tissue. Pesticide uptake by Phragmites was positively correlated with evapotranspiration. Pesticide removal from the hydroponic solution was not enantioselective. However, tebuconazole was degraded enantioselectively both in the roots and shoots. Imazalil translocation and degradation inside Phragmites were also enantioselective: R-imazalil translocated faster than S-imazalil.

Enantiomeric fraction and isomeric composition to assess sources of DDT residues in soils.

Chiral pesticides such as o,p'-DDT can undergo enantioselective microbial degradation in soil. Hence, the enantiomeric fraction (EF) of o,p'-DDT was used as an approach to assess potential recent inputs of DDT in the lower part of the Ebro River basin (NE Spain), a region heavily impacted by agricultural and industrial activities, including a dicofol production and a chloro-alkali plants. The EFs of five out of nineteen soils were not different from the racemic value (0.505±0.010), confirming that the Ebro River and some of its tributaries, Segre and Cinca rivers, transported fresh DDT residues despite its ban in Spain during the 90 s. o,p'-DDT/p,p'-DDT ratios in soils suggest that recent use of technical DDT and/or DDT-contaminated dicofol may be responsible for the fresh DDT inputs in the Segre River, while in the Ebro River, they indicate a dominant contribution of technical DDT, likely related to the residues accumulated by the chloro-alkali plant discharges.

Occurrence and behavior of the chiral anti-inflammatory drug naproxen in an aquatic environment.

The present study reports on the occurrence and chiral behavior of the anti-inflammatory drug (S)-naproxen (NAP)-(S)-2-(6-methoxynaphthalen-2-yl)propionic acid-in an aquatic environment under both field and laboratory conditions. In influents and effluents of sewage treatment plants (STPs) in the Tama River basin (Tokyo), (S)-NAP was detected at concentrations of 0.03 µg L(-1) to 0.43 µg L(-1) and 0.01 µg L(-1) to 0.11 µg L(-1), respectively. The concentrations of a major metabolite, 6-O-desmethyl NAP (DM-NAP) were up to 0.47 µg L(-1) and 0.56 µg L(-1) in influents and effluents, respectively. (R)-naproxen was not detected in STP influents, although it was present in effluents, and the enantiomeric faction (= S/[S + R]) of NAP ranged from 0.88 to 0.91. Under laboratory conditions with activated sludge from STPs, rapid degradation of (S)-NAP to DM-NAP and chiral inversion of (S)-NAP to (R)-NAP were observed. During river die-away experiments, degradation and chiral inversion of NAP were extremely slow. In addition, chiral inversion of (S)-NAP to (R)-NAP was not observed during photodegradation experiments. In the river receiving STP discharge, NAP and DM-NAP concentrations reached 0.08 µg L(-1) and 0.16 µg L(-1) , respectively. The enantiomeric faction of NAP in the river ranged from 0.84 to 0.98 and remained almost unchanged with the increasing contribution of rainfall to the river water. These results suggest that the absence and decrease of (R)-NAP in river waters could indicate the inflow of untreated sewage. E

Residues and chiral signatures of organochlorine pesticides in mollusks from the coastal regions of the Yangtze River Delta: source and health risk implication.

The residues and enantiomeric fractions of organochlorine pesticides (OCPs) were measured in 11 mollusk species collected from the coastal areas along the Yangtze River Delta to evaluate the status, potential sources, and health risks of pollution in these areas. The concentrations of DDTs, HCHs, and chlordanes ranged from 6.22 to 398.19, 0.66-7.11, and 0.14-4.08 ng g(-1) based on wet weight, respectively; DDTs and HCHs have the highest values, globally. The DDTs increased and the HCHs decreased compared to historical data. Both the box-and-whisker plots and the one-way ANOVA tests indicated that the OCP levels varied little between sampling locations and organism species. The compositions of the DDTs and HCHs suggested a cocktail input pattern of fresh and weathered technical products. The comparative EF values for the α-HCH between the sediments and mollusks, as well as the lack of any discernible difference in the relative proportions of HCH isomers among different species from the same sampling site implied that the HCH residues in the mollusks came directly from the surrounding environment. However, the biotransformation of DDTs in mollusks cannot be precluded. The assessments performed based on several available guidelines suggested that although no significant human health risks were associated with the dietary intake of OCPs, the concentrations of DDTs exceeded the maximum residual limits of China and many developed nations. Moreover, an increased lifetime cancer risk from dietary exposure to either DDTs or HCHs remains a possibility. Because non-racemic OCP residues are common in the mollusk samples, our results suggest a need to further explore the levels and toxicity of the chiral contaminants in mollusks and other foodstuff to develop the human risk assessment framework based on chiral signatures.