Environmental Fate Assessment Research Articles

Significance of non-DLVO interactions on the co-transport of levofloxacin and titanium dioxide nanoparticles in porous media

With the application of engineered nanomaterials and antibiotics in the fields of medicine, aerospace, new energy and agriculture, the associated contamination is detected widely in soil-groundwater systems. It is of great scientific and practical significance to deeply explore the environmental interface process between nanoparticles and antibiotics for the scientific assessment of environmental fate and ecological environmental risks, as well as the development of new composite pollution control technologies. In this study, the co-transport behaviors of positively charged titanium dioxide nanoparticles (TiO2-NPs) and negatively charged levofloxacin (LEV) in quartz sand (QS) are investigated in this study. The results show that TiO2-NPs hardly flow out when transported alone in the column because of its positive charge, which creates a strong attraction with the negatively charged quartz sand on the surface. When TiO2-NPs co-migrate with LEV in porous media, the presence of LEV promotes the transport of TiO2-NPs, while the presence of TiO2-NPs inhibits LEV transport. Non-XDLVO interactions based on molecular dynamics (MD) simulations can help explain the observed promotion and inhibition phenomena as well as the correlation between TiO2-NPs and LEV. The results indicate that TiO2-LEV complexes or aggregates can be formed during the co-transportation process of TiO2-NPs and LEV in porous media. As flow velocity increases from 0.204 cm min−1 to 1.630 cm min−1, both the transport capacities of TiO2-NPs and LEV are enhanced significantly. Under the condition of high citric acid (CA) concentration (15 mmol L−1), the transport capacity of TiO2-NPs is slightly inhibited, while the transport capacity of LEV is enhanced. This study provides new insights into the transport of nanometallic oxides and antibiotics in porous media, which suggests that non-XDLVO interactions should be considered together when assessing the environmental risks and fate of nanometallic oxides and antibiotics in soil-groundwater systems.

Comprehensive Assessment of Environmental Emissions, Fate, and Risks of Veterinary Antibiotics in China: An Environmental Fate Modeling Approach.

China is one of the major global consumers of veterinary antibiotics. Insufficient recognition of emissions and environmental contamination hamper global efforts to prevent antibiotic resistance development. This pioneering study combined empirical data and modeling approaches to predict total 2010-2020 emissions of 80 veterinary antibiotics ranging from 23,110 to 40,850 tonnes/year, after 36-50% antibiotic removal by manure treatment. Following an initial increase of 10% from 2010 to 2015, emissions declined thereafter by 43%. While 85% of emissions discharged into soils, approximately 56%, 23%, and 18% of environmental residue were ultimately distributed in soils, freshwaters, and seawaters under steady-state conditions. In 2020, 657 (319-1470) tonnes entered the ocean from inland freshwaters. Median ∑antibiotics concentrations were estimated at 4.7 × 103 ng/L in freshwaters and 2.9 ng/g in soils, with tetracyclines and sulfonamides as the predominant components. We identified 44 veterinary antibiotics potentially posing high risks of resistance development in freshwaters, with seven exhibiting high risks in >10% of Chinese freshwater areas. Tetracyclines were the category with the most antibiotics exhibiting elevated risks; however, sulfamethylthiazole demonstrated the highest individual compound risk. The Haihe River Basin displayed the highest susceptibility overall. The findings offer valuable support for control of veterinary antibiotic contamination in China.

Environmental considerations along the life cycle of pharmaceuticals: Interview study on views regarding environmental challenges, concerns, strategies, and prospects within the pharmaceutical industry

Environmental impacts of medicines arise throughout their entire life cycle. The pharmaceutical industry has a key role in reducing these impacts in early production phases, but currently has limited possibilities to reduce the environmental exposure arising from drug consumption and end-of-life. The aim of this interview study was to explore the current environmental actions within the industry, as well as the views and attitudes toward the strategies to address the environmental challenges and concerns. Semi-structured interviews were conducted among representatives (n = 15) from twelve pharmaceutical companies operating in Finland in February-May 2021. The data were analyzed using qualitative content analysis.The representatives of pharmaceutical industry were overall well aware of the multifaceted environmental challenges related to the life cycle of pharmaceuticals and of their role in improving sustainability in production. Improving waste management and reducing impacts from companies’ own operations were the most commonly mentioned actions already taking place within the companies (15/15). “Environmental impacts arising from drug consumption” (6/15) and “centralized drug manufacturing in countries with lax environmental regulation” (4/15) were most frequently brought up challenges difficult to resolve. “Development of environmentally more sustainable drug production in the company” was the most frequently raised key development need (5/15). To address this, establishment of tangible economic drivers, regulatory incentives, or reputational rewards were called for. “Incorporation of environmental aspects into decision-making in different situations” was suggested by 11/15 interviewees as a means to promote sustainable development, e.g. in selection of medicines by physicians and consumers. However, the attitudes towards the types of criteria and their evaluation differed between interviewees. Attitudes towards the “incorporation of environmental fate assessment into early phases of drug design and development” were mostly positive (10/11), suggesting that there is a keen interest in the industry to foster the introduction of new tools enabling the development of pharmaceuticals intrinsically less harmful for the environment.

Comprehensive Stereoselectivity Assessment of Toxicokinetics, Tissue Distribution, Cytotoxicity, and Environmental Fate of Chiral Pesticide Propiconazole.

Propiconazole (PRO) has been widely used in the treatment of fungal infection in fruits, vegetables, cereals, and seeds. In this study, a newly established chiral liquid chromatography tandem mass spectrometry method was applied to the systemic stereoselectivity evaluation of PRO enantiomers, including toxicokinetics, tissue distributions, cytotoxicity, accumulation, and degradation. Our results showed that both trans (+)-2S,4S-PRO and cis (-)-2S,4R-PRO had lower Cmax and AUC0-∞ and higher CLz/F values in plasma and lower accumulation concentrations in the liver, heart, and brain. In cytotoxic assays, cis (-)-2S,4R-PRO exhibited the lowest cytotoxicity in PC12 neuronal, N9 microglia, SH-SY5Y neuroblastoma, and MRC5 lung fibroblast cell lines. Moreover, the Eisenia fetida incubation experiment revealed that the accumulations of both trans (+)-2S,4S-PRO and cis (-)-2S,4R-PRO were higher than those of their antipodes in E. fetida. In summary, our findings first suggested that the application of cis (-)-2S,4R-PRO for agriculture would hugely reduce the environmental risk.

A framework for prioritizing contaminants in retrospective ecological assessments: Application in the Milwaukee Estuary (Milwaukee, WI).

Watersheds are subjected to diverse anthropogenic inputs, exposing aquatic biota to a wide range of chemicals. Detection of multiple, different chemicals can challenge natural resource managers who often have to determine where to allocate potentially limited resources. Here, we describe a weight-of-evidence framework for retrospectively prioritizing aquatic contaminants. To demonstrate framework utility, we used data from 96-h caged fish studies to prioritize chemicals detected in the Milwaukee Estuary (WI, USA; 2017-2018). Across study years, 77/178 targeted chemicals were detected. Chemicals were assigned prioritization scores based on spatial and temporal detection frequency, environmental distribution, environmental fate, ecotoxicological potential, and effect prediction. Chemicals were sorted into priority bins based on the intersection of prioritization score and data availability. Data-limited chemicals represented those that did not have sufficient data to adequately evaluate ecotoxicological potential or environmental fate. Seven compounds (fluoranthene, benzo[a]pyrene, pyrene, atrazine, metolachlor, phenanthrene, and DEET) were identified as high or medium priority and data sufficient and flagged as candidates for further effects-based monitoring studies. Twenty-one compounds were identified as high or medium priority and data limited and flagged as candidates for further ecotoxicological research. Fifteen chemicals were flagged as the lowest priority in the watershed. One of these chemicals (2-methylnaphthalene) displayed no data limitations and was flagged as a definitively low-priority chemical. The remaining chemicals displayed some data limitations and were considered lower-priority compounds (contingent on further ecotoxicological and environmental fate assessments). The remaining 34 compounds were flagged as low or medium priority. Altogether, this prioritization provided a screening-level (non-definitive) assessment that could be used to focus further resource management and risk assessment activities in the Milwaukee Estuary. Furthermore, by providing detailed methodology and a practical example with real experimental data, we demonstrated that the proposed framework represents a transparent and adaptable approach for prioritizing contaminants in freshwater environments. Integr Environ Assess Manag 2023;19:1276-1296. © 2022 SETAC.

Exploring quantitative structure-property relationship models for environmental fate assessment of petroleum hydrocarbons.

The rate and extent of biodegradation of petroleum hydrocarbons in the different aquatic environments is an important element to address. The major avenue for removing petroleum hydrocarbons from the environment is thought to be biodegradation. The present study involves the development of predictive quantitative structure-property relationship (QSPR) models for the primary biodegradation half-life of petroleum hydrocarbons that may be used to forecast the biodegradation half-life of untested petroleum hydrocarbons within the established models' applicability domain. These models use easily computable two-dimensional (2D) descriptors to investigate important structural characteristics needed for the biodegradation of petroleum hydrocarbons in freshwater (dataset 1), temperate seawater (dataset 2), and arctic seawater (dataset 3). All the developed models follow OECD guidelines. We have used double cross-validation, best subset selection, and partial least squares tools for model development. In addition, the small dataset modeler tool has been successfully used for the dataset with very few compounds (dataset 3 with 17 compounds), where dataset division was not possible. The resultant models are robust, predictive, and mechanisticallyinterpretable based on both internal and external validation metrics (R2 range of 0.605-0.959. Q2(Loo) range of 0.509-0.904, and Q2F1 range of 0.526-0.959). The intelligent consensus predictor tool has been used for theimprovement of the prediction quality for test set compounds which provided superior outcomes to those from individual partial least squares models based on several metrics (Q2F1 = 0.808 and Q2F2 = 0.805 for dataset 1 in freshwater). Molecular size and hydrophilic factor for freshwater, frequency of two carbon atoms at topological distance 4 for temperate seawater, and electronegative atom count relative to size for arctic seawater were found to be the most significant descriptors responsible for the regulation of biodegradation half-life of petroleum hydrocarbons.

Statement concerning the assessment of environmental fate and behaviour and ecotoxicology in the context of the pesticides peer review of the active substance dimoxystrobin.

In August 2022, the European Commission asked EFSA to provide a statement on the available outcomes of the assessment of environmental fate and behaviour and ecotoxicology drawn in the context of the pesticides peer review for the renewal of approval of the active substance dimoxystrobin conducted in accordance with Commission Implementing Regulation (EC) No 844/2012. The current statement contains the conclusions of the assessments related to environmental fate and behaviour and ecotoxicology finalised following the pesticides peer review expert discussions held in January and June 2022. The concerns identified are presented.

An Overview of Light-Mediated Impact of Graphene Oxide on Algae: Photo-Transform, Toxicity and Mechanism

Due to the unique chemical and physical properties, graphene-based nanomaterials are increasingly being introduced into various scientific fields. They all play very important roles in different fields and are widely used. Graphene oxide (GO) is one of the most popular and representative carbon nanomaterials; scientists have great research interest in it. When carbon nanomaterials such as GO are released into the aquatic environment, their physicochemical properties will be influenced by natural light, resulting in the potential change in toxic effects on aquatic organisms. Algae, as a typical aquatic organism, is extensively regarded as a model microorganism to assess the biotoxicity of nanomaterials. In this review, we overview the light-mediated impact of GO on algae. We summarize the photo-transformation of GO under different illumination conditions and the effect of illumination on the physicochemical properties of GO. Then, we combined metabolomics, genotoxicity, and proteomics with standard toxicity assays (cell division, membrane permeability, oxidative stress, photosynthesis, cellular ultrastructure, and so on) to compare native and environmentally transformed GO induction toxicological mechanisms. By correlating lights, physicochemical properties, and biotoxicity, this review is valuable for environmental fate assessments on graphene-based nanoparticles, providing a theoretical basis and support for evaluating the potential ecological health and environmental risks of graphene-based nanoparticles in real natural water environments.

Development of a Preemergent Nanoherbicide: From Efficiency Evaluation to the Assessment of Environmental Fate and Risks to Soil Microorganisms.

Nanoparticles based on biodegradable polymers have been shown to be excellent herbicide carriers, improving weed control and protecting the active ingredient in the crop fields. Metribuzin is often found in natural waters, which raises environmental concerns. Nanoencapsulation of this herbicide could be an alternative to reduce its losses to the environment and improve gains in its efficiency. However, there is a paucity of information about the behavior of nanoformulations of herbicides in environmental matrices. In this study, the stability of nanoencapsulated metribuzin in polymeric nanoparticles (nanoMTZ) was verified over time, as well as its dissipation in different soils, followed by the effects on soil enzymatic activity. The physiological parameters and control effects of nanoMTZ on Ipomoea grandifolia plants were investigated. No differences were verified in the half-life of nanoencapsulated metribuzin compared to a commercial formulation of the herbicide. Moreover, no suppressive effects on soil enzymatic activities were observed. The retention of nanoMTZ in the tested soils was lower compared to its commercial analogue. However, the mobility of nanoencapsulated metribuzin was not greatly increased, reflecting a low risk of groundwater contamination. Weed control was effective even at the lowest dose of nanoMTZ (48 g a.i. ha-1), which was consistent with the higher efficiency of nanoMTZ compared to the conventional herbicide in inhibiting PSII activity and decreasing pigment levels. Overall, we verified that nanoMTZ presented a low environmental risk, with increased weed control.

Integrating Process‐Based Reactive Transport Modeling and Machine Learning for Electrokinetic Remediation of Contaminated Groundwater

AbstractAdvanced reactive transport models of fluid flow and solute transport in subsurface porous media are instrumental for the assessment of contaminant environmental fate and for the design of in situ remediation interventions. However, the increasing complexity of process‐based reactive transport simulators often leads to long runtimes, which poses severe restrictions for tasks that require numerous model evaluations. To overcome this limitation, we demonstrate how machine learning surrogate models, trained on the outputs of a limited number of process‐based reactive transport simulations, can predict the evolution of complex subsurface systems. We focus on electrokinetic enhanced bioremediation of chlorinated solvents in low‐permeability porous media, which is an in situ remediation technology entailing a suite of complex and coupled physical, chemical, and biological processes. A process‐based, multicomponent reactive transport model, capable of describing the key mechanisms of electrokinetic flow and transport, is setup in a two‐dimensional domain. The model accounts for electromigration and electroosmosis, the electrostatic interactions between charged species, the chemistry of the pore water solution, the microbially mediated degradation of the organic compounds, and the dynamics of different degraders. We develop a response surface surrogate framework using an artificial neural network as approximation function and we show that the surrogate model has the capability and the flexibility to capture the complex dynamics of electrokinetic remediation in subsurface porous media and allows computationally efficient model exploration, sensitivity analysis, and uncertainty quantification.

Highly variable soil dissipation of metaldehyde can explain its environmental persistence and mobility

There are increasing concerns about the hazard posed to drinking water resources by persistent, mobile, and toxic (PMT) substances in the environment. For example, the extensive use of metaldehyde-based molluscicide to control slug populations in agricultural fields has frequently led to pollution of surface waters and contamination of drinking water at levels exceeding the statutory limit. Regulatory environmental fate assessments and studies in the literature did not predict that metaldehyde would be persistent in the environment, contrary to observations from monitoring schemes. To understand the reasons for this disparity, this study conducted a suite of degradation experiments, covering different soil types and environmentally realistic conditions in Northern Europe, and generated a distribution of DT50 values for metaldehyde to examine whether degradation rates are underestimated by current risk assessments. The results were found to vary, showing DT50 values ranging from 3.0 to 4150 days, which indicated that metaldehyde had the potential to become persistent. Lack of prior metaldehyde exposure, high moisture content, low temperature, and locally high metaldehyde concentration under pellets were identified as high-risk conditions for low pesticide biodegradation in UK soils.

Micro and Nano-Plastics in the Environment: Research Priorities for the Near Future.

Plastic litter dispersed in the different environmental compartments represents one of the most concerning problems associated with human activities. Specifically, plastic particles in the micro and nano size scale are ubiquitous and represent a threat to human health and the environment. In the last few decades, a huge amount of research has been devoted to evaluate several aspects of micro/nano-plastic contamination: origin and emissions, presence in different compartments, environmental fate, effects on human health and the environment, transfer in the food web and the role of associated chemicals and microorganisms. Nevertheless, despite the bulk of information produced, several knowledge gaps still exist. The objective of this paper is to highlight the most important of these knowledge gaps and to provide suggestions for the main research needs required to describe and understand the most controversial points to better orient the research efforts for the near future. Some of the major issues that need further efforts to improve our knowledge on the exposure, effects and risk of micro/nano-plastics are: harmonization of sampling procedures; development of more accurate, less expensive and less time-consuming analytical methods; assessment of degradation patterns and environmental fate of fragments; evaluating the capabilities for bioaccumulation and transfer to the food web; and evaluating the fate and the impact of chemicals and microorganisms associated with micro/nano-plastics. The major gaps in all sectors of our knowledge, from exposure to potentially harmful effects, refer to small size microplastics and, particularly, to the occurrence, fate and effects of nanoplastics.

Effect of food on orally-ingested titanium dioxide and zinc oxide nanoparticle behaviors in simulated digestive tract

Nanomaterials have been widely utilized in human daily life. The interaction between nanoparticles (NPs) and food matrices through oral ingestion is important for fate and potential toxicity of NPs. In this study, the interaction between NPs (i.e., titanium dioxide (TiO2) and zinc oxide (ZnO)) and food matrices (namely sucrose, protein powder, and corn oil) was investigated by use of an in vitro physiological model. Measurement using asymmetrical flow field-flow fractionation (AF4) showed that particle size of TiO2 NPs in saliva fluid decreased from 102 ± 6.21 nm (control) to 69.2 ± 6.90 and 81.9 ± 4.30 nm in protein powder and corn oil. Similar trend was also observed for ZnO. Compared with gastric fluid, micelles formed by corn oil in intestinal fluid further dispersed NPs, as indicated by approximately 11.1% and 13.2% decrease in particle size of TiO2 and ZnO NPs, respectively. Characterization of TEM, FTIR and AFM showed that a layer of biological corona was attached on surface of NPs in protein and oil. The XPS demonstrated that oil bound with NPs through forming covalent bonds, while protein bound with NPs through van der Waals force and electrostatic force for TiO2 and ZnO NPs, respectively. The result here demonstrated the importance of considering food effect when investigating the morphology and behavior of NPs after oral ingestion. This understanding was valuable in assessment of environmental fate and biological effects of NPs.

Colloidal properties and stability of UV-transformed graphene oxide in aqueous solutions: The role of disorder degree

Motivated by the use of ultraviolet (UV) radiation in the disinfection processes of drinking and waste water treatment plants, this study explores the colloidal properties and stability of UV irradiated graphene oxide (GO) by using the batch technique and time-resolved dynamic light scattering over a wide range of salt types (NaCl, MgCl2, and CaCl2) and ionic strength relevant to engineered and natural systems. The results show that the UV irradiation time has an important impact on the physicochemical properties of GO and consequently on its colloidal properties and stability. The aggregation kinetics, attachment efficiency and critical coagulation concentration (CCC) values of UV irradiated GO are obtained for the first time. By correlating CCC values with physicochemical properties, we find that the disorder degree plays a more important role in colloidal properties and stability of UV irradiated GO than oxygen containing functional groups. The findings are valuable for environmental fate assessments on various families of functionalized GO.

The photodegradation of 1,3,6,8-tetrabromocarbazole in n-hexane and in solid-mediated aqueous system: Kinetics and transformation mechanisms

The kinetics and mechanisms of photochemical transformation of 1,3,6,8-tetrabromocarbazole (1368-BCZ) in n-hexane and pre-coated on solid particles in aqueous solution are investigated. Under simulated sunlight irradiation, 1368-BCZ dissolved in n-hexane rapidly photodegraded, obeying the pseudo first-order kinetics model. In the aqueous system, particles of seven different solids with coated 1368-BCZ were suspended during the reaction. The photodegradation kinetics of 1368-BCZ on three pure particles (silica gel, Al2O3, and Kaolin) fitted with the “double-logarithmic” model. At pH = 7.0 and T = 15 °C, 84% of 1368-BCZ with initial coating concentration of 100 μg g−1 silica gel disappeared in 1 h. The products and intermediates identified suggested that debromination and hydroxylation were the two main photochemical transformation pathways of 1368-BCZ in both n-hexane and aqueous systems. The proposed reaction pathways were supported by the results of quantum chemical calculation. However, several products including 1-monobromocarbazole (1-BCZ), 3-monobromocarbazole (3-BCZ), dibromocarbazole-1 (di-BCZ-1), and 3,6-dibromocarbazole (36-BCZ) were found during the reaction in n-hexane but not detected in the aqueous systems. This work provides useful information in the assessment of environmental fate of polyhalogenated carbazoles.

Microbial Turnover of Glyphosate to Biomass: Utilization as Nutrient Source and Formation of AMPA and Biogenic NER in an OECD 308 Test

Environmental fate assessment of chemicals involves standardized simulation tests with isotope-labeled molecules to balance transformation, mineralization, and formation of nonextractable residues (NER). Methods to predict microbial turnover and biogenic NER have been developed, having limited use when metabolites accumulate, the chemicals are not the only C source, or provide for other macroelements. To improve predictive capability, we extended a recently developed method for microbial growth yield estimation to account for incomplete degradation and multiple-element assimilation and combined it with a dynamic model for fate description in soils and sediments. We evaluated the results against the unique experimental data of 13C3-15N co-labeled glyphosate turnover with AMPA formation in water-sediment systems (OECD 308). Balancing 13C- and 15N- fluxes to biomass showed a pronounced shift of glyphosate transformation from full mineralization to AMPA formation. This may be explained by various hypotheses, for example, the limited substrate turnover inherent to the batch conditions of the test system causing microbial starvation or inhibition by P release. Modeling results indicate initial N overload due to the lower C/N ratio in glyphosate compared to average cell composition leading to subsequent C demand and accumulation of AMPA.

Prioritization of pharmaceuticals in drinking water exposure based on toxicity and environmental fate assessment by in silico tools: An integrated and transparent ranking

The concentration of pharmaceuticals in water and health risk to the human population is a topic of concern among the scientific community, regulators, and the general population. Many recent studies have suggested different, even conflicting, criteria for the definition of priority pharmaceuticals for drinking-water exposure. In this work, we assessed 10 endpoints of environmental fate and human toxicity for 39 active pharmaceutical ingredients (APIs) by in silico models and data review. A visual and transparent Toxicological Prioritization Index (ToxPi) was proposed based on in silico, in chemico, in vitro, and in vivo results. Predictions of environmental fate and toxicity were made through in silico models of EPISuiteTM, PBT Profiler v.2, TEST v4.2 and QSAR Toolbox v.3.2. The software ToxPi GUI was used to create a multicriteria-based ranking with environmental fate and human toxicity endpoints to identify priority compounds. Our multicriteria ranking (fate and hazard-based) suggested that the some of the most concerning APIs were metronidazole (ToxPi: 5.67; CI95%: 5.51–5.83), nitrofurantoin (ToxPi: 5.22 CI95%: 5.21–5.22) and ethinylestradiol (ToxPi: 5.20; CI95%: 4.70–5.79). Different APIs may represent high level of concern by different characteristics of environmental exposure and/or toxicity, and our visual muticriteria ranking can support targeted decision-making. Computational tools may be important for predicting environmental fate and toxicity as well as visually identifying priority compounds by multicriteria-based rankings and predicting compounds with high priority to support more targeted multicriteria decision-making, risk assessment, and monitoring steps.

Measurement of Vapor Pressures and Melting Properties of Five Polybrominated Aromatic Flame Retardants

While vapor pressure is among the most important properties used in the environmental fate assessment of organic contaminants, measured vapor pressures exist only for a few representatives of the group of novel brominated flame retardants (BFRs). To expand on this limited set of data, the vapor pressures of five BFRs—1,2,4,5,-tetrabromo-dimethylbenzene (TBX), 1,2,3,4,5-pentabromo-6-methyl-benzene (PBT), 1,2,3,4,5-pentabromo-6-ethyl-benzene (PBEB), 2,3,4,5,6-pentabromo-phenol (PBP), and 1,3,5-tribromo-2(2,3-dibromopropoxy)-benzene (TBP-DBPE)—were measured in the temperature range 322.7–367.7 K with the gas saturation method. Enthalpies of sublimation or vaporization were determined from the slopes of semilogarithmic plots of measured vapor pressure against reciprocal temperature. The melting temperature and enthalpy of fusion were measured using differential scanning calorimetry. From these experimental data, the vapor pressures and subcooled liquid vapor pressures at 298.2 K, pi° and pi°,sl, respectively,...

Discovery of a Novel Polyfluoroalkyl Benzenesulfonic Acid around Oilfields in Northern China.

The existence of more than 3000 per- and polyfluoroalkyl substances (PFASs) on the global market has prompted the identification and hazard characterization of hitherto unknown PFASs. In the present study, a novel PFAS, sodium p-perfluorous nonenoxybenzenesulfonate (OBS), was identified using Orbitrap MS/MS in water samples around a suspected application area, Daqing Oilfield, China. The peak OBS concentration was 3.2 × 103 ng/L in a sample taken near the oil well with the longest production history in Daqing. The concentrations of OBS and contribution to the sum of PFASs in surface waters displayed considerable variation among the three sampling areas (mean levels at 6.9, 50, and 5.6 × 102 ng/L with mean percentages at 9.8%, 45%, and 69% in the background, new and old oilfield areas respectively) confirming that the density of oil wells and the oil production history are important factors influencing OBS contamination in the studied areas. A preliminary assessment of acute toxicity and environmental fate indicates that OBS exhibits similar toxicity and environmental persistence to perfluorooctanesulfonic acid (PFOS). The widespread occurrence of OBS, in conjunction with its potential hazard properties, underscores the need to further study on the bioaccumulation and potential for human exposure.

Demonstration of a consensus approach for the calculation of physicochemical properties required for environmental fate assessments

Eight software applications are compared for their performance in estimating the octanol-water partition coefficient (Kow), melting point, vapor pressure and water solubility for a dataset of polychlorinated biphenyls, polybrominated diphenyl ethers, polychlorinated dibenzodioxins, and polycyclic aromatic hydrocarbons. The predicted property values are compared against a curated dataset of measured property values compiled from the scientific literature with careful consideration given to the analytical methods used for property measurements of these hydrophobic chemicals. The variability in the predicted values from different calculators generally increases for higher values of Kow and melting point and for lower values of water solubility and vapor pressure. For each property, no individual calculator outperforms the others for all four of the chemical classes included in the analysis. Because calculator performance varies based on chemical class and property value, the geometric mean and the median of the calculated values from multiple calculators that use different estimation algorithms are recommended as more reliable estimates of the property value than the value from any single calculator.