Should Transformation Products Change the Way We Manage Chemicals?

When chemical pollutants enter the environment, they can undergo diverse transformation processes, forming a wide range of transformation products (TPs), some of them benign and others more harmful than their precursors. To date, the majority of TPs remain largely unrecognized and unregulated, particularly as TPs are generally not part of routine chemical risk or hazard assessment. Since many TPs formed from oxidative processes are more polar than their precursors, they may be especially relevant in the context of persistent, mobile, and toxic (PMT) and very persistent and very mobile (vPvM) substances, which are two new hazard classes that have recently been established on a European level. We highlight herein that as a result, TPs deserve more attention in research, chemicals regulation, and chemicals management. This perspective summarizes the main challenges preventing a better integration of TPs in these areas: (1) the lack of reliable high-throughput TP identification methods, (2) uncertainties in TP prediction, (3) inadequately considered TP formation during (advanced) water treatment, and (4) insufficient integration and harmonization of TPs in most regulatory frameworks. A way forward to tackle these challenges and integrate TPs into chemical management is proposed.

Eco-toxicological and climate change effects of sludge thermal treatments: Pathways towards zero pollution and negative emissions.

The high moisture content and the potential presence of hazardous organic compounds (HOCs) and metals (HMs) in sewage sludge (SS) pose technical and regulatory challenges for its circular economy valorisation. Thermal treatments are expected to reduce the volume of SS while producing energy and eliminating HOCs. In this study, we integrate quantitative analysis of SS concentration of 12 HMs and 61 HOCs, including organophosphate flame retardants (OPFRs) and per- and poly-fluoroalkyl substances (PFAS), with life-cycle assessment to estimate removal efficiency of pollutants, climate change mitigation benefits and toxicological effects of existing and alternative SS treatments (involving pyrolysis, incineration, and/or anaerobic digestion). Conventional SS treatment leaves between 24 % and 40 % of OPFRs unabated, while almost no degradation occurs for PFAS. Thermal treatments can degrade more than 93% of target OPFRs and 95 % of target PFAS (with the rest released to effluents). The different treatments affect how HMs are emitted across environmental compartments. Conventional treatments also show higher climate change impacts than thermal treatments. Overall, thermal treatments can effectively reduce the HOCs emitted to the environment while delivering negative emissions (from about -56 to -111 kg CO2-eq per tonne of sludge, when pyrolysis is involved) and producing renewable energy from heat integration and valorization.

Stabilization of PFAS-contaminated soil with sewage sludge- and wood-based biochar sorbents.

Sustainable and effective remediation technologies for the treatment of soil contaminated with per- and polyfluoroalkyl substances (PFAS) are greatly needed. This study investigated the effects of waste-based biochars on the leaching of PFAS from a sandy soil with a low total organic carbon content (TOC) of 0.57 ± 0.04 % impacted by PFAS from aqueous film forming foam (AFFF) dispersed at a former fire-fighting facility. Six different biochars (pyrolyzed at 700-900 °C) were tested, made from clean wood chips (CWC), waste timber (WT), activated waste timber (aWT), two digested sewage sludges (DSS-1 and DSS-2) and de-watered raw sewage sludge (DWSS). Up-flow column percolation tests (15 days and 16 pore volume replacements) with 1 % biochar indicated that the dominant congener in the soil, perfluorooctane sulphonic acid (PFOS) was retained best by the aWT biochar with a 99.9 % reduction in the leachate concentration, followed by sludge-based DWSS (98.9 %) and DSS-2 and DSS-1 (97.8 % and 91.6 %, respectively). The non-activated wood-based biochars (CWC and WT) on the other hand, reduced leaching by <42.4 %. Extrapolating this to field conditions, 90 % leaching of PFOS would occur after 15 y for unamended soil, and after 1200 y and 12,000 y, respectively, for soil amended with 1 % DWSS-amended and aWT biochar. The high effectiveness of aWT and the three sludge-based biochars in reducing PFAS leaching from the soil was attributed largely to high porosity in a pore size range (>1.5 nm) that can accommodate the large PFAS molecules (>1.02-2.20 nm) combined with a high affinity to the biochar matrix. Other factors like anionic exchange capacity could play a contributing role. Sorbent effectiveness was better for long-chain than for short-chain PFAS, due to weaker, apolar interactions between the biochar and the latter's shorter hydrophobic CF2-tails. The findings were the first to demonstrate that locally sourced activated wood-waste biochars and non-activated sewage sludge biochars could be suitable sorbents for the ex situ stabilization and in situ remediation of PFAS-contaminated soil, bringing this technology one step closer to full-scale field testing.

Exposure assessment of plastics, phthalate plasticizers and their transformation products in diverse bio-based fertilizers.

Bio-based fertilizers (BBFs) produced from organic waste have the potential to reduce societal dependence on limited and energy-intensive mineral fertilizers. BBFs, thereby, contribute to a circular economy for fertilizers. However, BBFs can contain plastic fragments and hazardous additives such as phthalate plasticizers, which could constitute a risk for agricultural soils and the environment. This study assessed the exposure associated with plastic and phthalates in BBFs from three types of organic wastes: agricultural and food industry waste (AgriFoodInduWaste), sewage sludge (SewSludge), and biowaste (i.e., garden, park, food and kitchen waste). The wastes were associated with various treatments like drying, anaerobic digestion, and vermicomposting. The number of microplastics (0.045-5 mm) increased from AgriFoodInduWaste-BBFs (15-258 particles g-1), to SewSludge-BBFs (59-1456 particles g-1) and then to Biowaste-BBFs (828-2912 particles g-1). Biowaste-BBFs mostly contained packaging plastics (e.g., polyethylene terephthalate), with the mass of plastic (>10 g kg-1) exceeding the EU threshold (3 g kg-1, plastics >2 mm). Other BBFs mostly contained small (< 1 mm) non-packaging plastics in amounts below the EU limit. The calculated numbers of microplastics entering agricultural soils via BBF application was high (107-1010 microplastics ha-1y-1), but the mass of plastic released from AgriFoodInduWaste-BBFs and SewSludge-BBFs was limited (< 1 and <7 kg ha-1y-1) compared to Biowaste-BBFs (95-156 kg ha-1y-1). The concentrations of di(2-ethylhexyl)phthalate (DEHP; < 2.5 mg kg-1) and phthalate transformation products (< 8 mg kg-1) were low (< benchmark of 50 mg kg-1 for DEHP), attributable to both the current phase-out of DEHP as well as phthalate degradation during waste treatment. The Biowaste-BBF exposed to vermicomposting indicated that worms accumulated phthalate transformation products (4 mg kg-1). These results are overall positive for the implementation of the studied AgriFoodInduWaste-BBFs and SewSludge-BBFs. However, the safe use of the studied Biowaste-BBFs requires reducing plastic use and improving sorting methods to minimize plastic contamination, in order to protect agricultural soils and reduce the environmental impact of Biowaste-BBFs.

Machine learning coupled with causal inference to identify COVID-19 related chemicals that pose a high concern to drinking water.

Various synthetic substances were utilized in large quantities during the recent coronavirus pandemic, COVID-19. Some of these chemicals could potentially enter drinking water sources. Persistent, mobile, and toxic (PMT) substances have been recognized as a threat to drinking water resources. It has not yet been assessed how many COVID-19 related substances could be considered PMT substances. One reason is the lack of high-quality experimental data for the identification of PMT substances. To solve this problem, we applied a machine learning model to identify the PMT substances among COVID-19 related chemicals. The optimal model achieved an accuracy of 90.6% based on external test data. The model interpretation and causal inference indicated that our approach understood causation between PMT properties and molecular descriptors. Notably, the screening results showed that over 60% of the COVID-19 chemicals considered are candidate PMT substances, which should be prioritized to prevent undue pollution of water resources.

Per- and polyfluoroalkyl substance (PFAS) removal from soil washing water by coagulation and flocculation.

Soil washing is currently attracting attention as a promising remediation strategy for land contaminated with per- and polyfluoroalkyl substances (PFAS). In the soil washing process, the contaminant is transferred from the soil into the liquid phase, producing a PFAS contaminated process water. One way to treat such process water is to use coagulation and flocculation; however, few studies are available on the performance of coagulation and flocculation for removing PFAS from such process water. This study evaluated 6 coagulants and flocculants (polyaluminium chloride (PACl), zirconium oxychloride octahydrate, cationic and anionic polyacrylamide, Polyclay 685 and Perfluor Ad®), for the treatment of a proxy PFAS contaminated washing water, spiked with PFAS concentrations found at typical Aqueous Film Forming Foam (AFFF) contaminated sites. PFAS removal efficiencies (at constant pH) varied greatly depending on the coagulants and flocculants, as well as the dosage used and the targeted PFAS. All tested coagulants and flocculants reduced the turbidity by >95%, depending on the dosage. Perfluor Ad®, a specially designed coagulant, showed the highest removal efficiency for all longer chain (>99%) and shorter chain PFAS (>68%). The cationic polyacrylamide polymer removed longer chain PFAS up to an average of 80%, whereas average shorter chain PFAS removal was lower (<30%). The two metal-based coagulants tested, PACl and zirconium, removed longer chain PFAS by up to an average of 61% and shorter chain PFAS up to 48%. Polyclay 685, a mixture of powdered activated carbon (PAC) and aluminium sulphate, removed longer chain PFAS by 90% and shorter chain PFAS on average by 76%, when very high dosages of the coagulant were used (2,000 mg/L). PFAS removal efficiencies correlated with chain length and headgroup. Shorter chain PFAS removal was dependent on electrostatic interaction with the precipitating flocs, whereas for longer chain PFAS, hydrophobic interactions between apolar functional groups and flocs created by the coagulant/flocculant, dissolved organic matter and suspended solids played a major role. The results of this study showed that by selecting the most efficient coagulant and aqueous conditions, a greater amount of PFAS can be removed from process waters in soil washing facilities, and thus included as part of various treatment trains.

Developing machine learning approaches to identify candidate persistent, mobile and toxic (PMT) and very persistent and very mobile (vPvM) substances based on molecular structure.

Determining which substances on the global market could be classified as persistent, mobile and toxic (PMT) substances or very persistent, very mobile (vPvM) substances is essential to prevent or reduce drinking water contamination from them. This study developed machine learning models based on different molecular descriptors (MDs) and defined applicability domains for the screening of PMT/vPvM substances. The models were trained with 3111 substances with expert weight-of-evidence based PMT/vPvM hazard classifications that considered the highest quality data available. The model was based on the hypothesis that PMT/vPvM substances contain similar MDs, representative of chemical structures resistant to degradation, be associated with low sorption (or high-water solubility) and in some cases be associated with known toxic mechanisms. All possible model combinations were tested by integrating different molecular description methods, data balancing strategies and machine learning algorithms. Our model allows one-step prediction of candidate PMT/vPvM substances, and our method was compared with the approach predicting P, M and T separately (i.e. three-step prediction). The results showed that the one-step model achieved a higher accuracy of 92% for PMT/vPvM identification (i.e. positive samples) for an internal test set, and also resulted in a higher accuracy of 90% for an external test set of chemical pollutants detected in Taihu Lake, China. Furthermore, prediction mechanism of the model was interpreted by Shapley additive explanations (SHAP). This work presents an advance of big data in silico screening models for the identification of substances that potentially meet the PMT/vPvM criteria.

Soil Metabolome Impacts the Formation of the Eco-corona and Adsorption Processes on Microplastic Surfaces.

The eco-corona on microplastics refers to the initial layer of biomolecular compounds adsorbed onto the surface after environmental exposure. The formation and composition of the eco-corona in soils have attracted relatively little attention; however, the eco-corona has important implications for the fate and impacts of microplastics and co-occurring chemical contaminants. Here, it was demonstrated that the formation of the eco-corona on polyethylene microplastics exposed to water-extractable soil metabolites (WESMs) occurs quite rapidly via two pathways: direct adsorption of metabolites on microplastics and bridging interactions mediated by macromolecules. The main eco-corona components were common across all soils and microplastics tested and were identified as lipids and lipid-like molecules, phenylpropanoids and polyketides, nucleosides, nucleotides, and their analogues. WESMs were found to reduce the adsorption of co-occurring organic contaminants to microplastics by two pathways: reduced adsorption to the eco-corona surface and co-solubilization in the surrounding water. These impacts from the eco-corona and the soil metabolome should be considered within fate and risk assessments of microplastics and co-occurring contaminants.

Electrochemical Oxidation for Treatment of PFAS in Contaminated Water and Fractionated Foam-A Pilot-Scale Study.

Per- and polyfluoroalkyl substances (PFAS) are persistent synthetic contaminants that are present globally in water and are exceptionally difficult to remove during conventional water treatment processes. Here, we demonstrate a practical treatment train that combines foam fractionation to concentrate PFAS from groundwater and landfill leachate, followed by an electrochemical oxidation (EO) step to degrade the PFAS. The study combined an up-scaled experimental approach with thorough characterization strategies, including target analysis, PFAS sum parameters, and toxicity testing. Additionally, the EO kinetics were successfully reproduced by a newly developed coupled numerical model. The mean total PFAS degradation over the designed treatment train reached 50%, with long- and short-chain PFAS degrading up to 86 and 31%, respectively. The treatment resulted in a decrease in the toxic potency of the water, as assessed by transthyretin binding and bacterial bioluminescence bioassays. Moreover, the extractable organofluorine concentration of the water decreased by up to 44%. Together, these findings provide an improved understanding of a promising and practical approach for on-site remediation of PFAS-contaminated water.

The decomposition and emission factors of a wide range of PFAS in diverse, contaminated organic waste fractions undergoing dry pyrolysis.

Current treatment options for organic waste contaminated with per- and polyfluoroalkyl substances (PFAS) are generally limited to incineration, composting or landfilling, all resulting in emissions. Dry pyrolysis is a promising emerging alternative to these practices, but there is uncertainty related to the fate of PFAS during this process. The present work first developed a robust method for the determination of PFAS in complex matrices, such as sewage sludge and biochar. Then, a mass balance was established for 56 different PFAS during full-scale pyrolysis (2-10 kg biochar hr-1, 500-800 °C) of sewage sludges, food waste reject, garden waste and waste timber. PFAS were found in all wastes (56-3651 ng g-1), but pyrolysis resulted in a ≥ 96.9% removal. Residual PFAS (0.1-3.4 ng g-1) were detected in biochars obtained at temperatures up to 750 °C and were dominated by long chain PFAS. Emitted PFAS loads ranged from 0.01 to 3.1 mg tonne-1 of biochar produced and were dominated by short chain PFAS. Emissions made up < 3% of total PFAS-mass in the wastes. Remaining uncertainties are mainly related to the presence of thermal degradation products in flue gas and condensation oils.

Influence of grain size, organic carbon and organic matter residue content on the sorption of per- and polyfluoroalkyl substances in aqueous film forming foam contaminated soils - Implications for remediation using soil washing.

A soil that was historically contaminated with Aqueous Film Forming Foam (AFFF) was dry sieved into size fractions representative of those produced during soil washing. Batch sorption tests were then conducted to investigate the effect of soil parameters on in situ per- and polyfluoroalkyl substances (PFAS) sorption of these different size fractions: < 0.063 mm, 0.063 to 0.5 mm, 0.5 to 2 mm, 2 to 4 mm, 4 to 8 mm, and soil organic matter residues (SOMR). PFOS (513 ng/g), 6:2 FTS (132 ng/g) and PFHxS (58 ng/g) were the most dominant PFAS in the AFFF contaminated soil. Non-spiked, in situ Kd values for 19 PFAS ranged from 0.2 to 138 L/Kg (log Kd -0.8 to 2.14) for the bulk soil and were dependant on the head group and perfluorinated chain length (spanning C4 to C13). The Kd values increased with decreasing grain size and increasing organic carbon content (OC), which were correlated to each other. For example, the PFOS Kd value for silt and clay (< 0.063 mm, 17.1 L/Kg, log Kd 1.23) were approximately 30 times higher compared to the gravel fraction (4 to 8 mm, 0.6 L/Kg, log Kd -0.25). The highest PFOS Kd value (116.6 L/Kg, log Kd 2.07) was found for the SOMR fraction, which had the highest OC content. Koc values for PFOS ranged from 6.9 L/Kg (log Koc 0.84) for the gravel fraction to 1906 L/Kg (log Koc 3.28) for the silt and clay, indicating that the mineral composition of the different size fractions also influenced sorption. The results here emphasize the need to separate coarse-grained fractions and fine-grained fractions, and in particular the SOMR, to optimize the soil washing process. Higher Kd values for the smaller size fractions indicate that coarser soils are better suited for soil washing.

Analysis, occurrence and removal efficiencies of organophosphate flame retardants (OPFRs) in sludge undergoing anaerobic digestion followed by diverse thermal treatments.

Organophosphate flame retardants (OPFRs) are a complex group of contaminants to deal with in sewage sludge, as currently there is a lack of robust analytical methods to measure them and management strategies to remove them. To facilitate quantifications of the occurrence of OPFRs in sludge and to establish their removal efficiencies (REs%) during thermal treatments, a simple, reliable, and rapid sample preparation methodology was developed for the determination of 21 OPFRs in diverse sludge, ash and biochar matrices. Matrix-solid phase dispersion (MSPD) tailored to ultra-performance liquid chromatography (UPLC) coupled to tandem mass spectrometry (MS/MS) was applied. Under optimal conditions, 0.5 g of freeze-dried sample were dispersed in 2 g of Bondesil C18, and 1.5 g of deactivated florisil were used as clean-up sorbent. The target analytes were extracted with 5 mL of acetone. The obtained extract was ready for analysis within 20 min without the need of any further treatment. The proposed methodology was assessed, providing absolute recoveries (Abs%) ranging from 50.4 to 112 % with good method repeatability (RSDs <17.9 %). Method limits of quantification ranged from 0.10 to 14.0 ng g-1 dry weight (d.w.). The optimized methodology was applied to raw-, digested-, combusted and pyrolyzed sludge samples collected from different waste treatment plants located in Norway, where 16 out of 21 OPFRs were detected in digested sludge samples up to 2186 ng g-1 (d.w.; sum concentration of OPFRs). Diverse thermal treatments of combustion and dry pyrolysis were assessed for the removal of OPFRs from sludge. Combustion at 300 °C reduced the concentrations of OPFRs by 98 % (in the ashes formed), whereas pyrolysis at temperatures >500 °C effectively removed the OPFRs in the produced biochar. Thermal treatments, in particularly dry pyrolysis, showed potential for achieving zero pollution management and recycling of OPFR contaminated sludge.

Assessing and managing environmental hazards of polymers: historical development, science advances and policy options.

Polymers are the main constituents of many materials and products in our modern world. However, their environmental safety is not assessed with the same level of detail as done for non-polymeric chemical substances. Moreover, the fundamentals of contemporary regulatory approaches for polymers were developed in the early 1990s, with little change occurring since then. Currently, the European Commission is working on a proposal to initiate registration of polymers under the European Union's (EU) chemicals legislation REACH. This provides a unique opportunity for regulation to catch up on recent scientific advances. To inform this process, we here critically appraise the suggested regulatory approaches to the environmental assessment and management of polymers against the latest scientific findings regarding their environmental fate, exposure, and effects, and identify the remaining critical knowledge gaps. While we use the EU draft proposal as an example, our findings are broadly applicable to other polymer legislations worldwide, due to the similarity of polymer assessment criteria being used. We emphasize four major aspects that require more attention in the regulation of polymers: (i) increased transparency about chemical identities, physical characteristics and grouping approaches for in-use polymers; (ii) improved understanding of the environmental fate of polymers and materials composed of polymers across size and density categories and exposure profiles; (iii) comprehensive assessment of the environmental hazards of polymers, considering the effects of degradation and weathering and taking into account the actual uptake, long-term toxicity, and geophysical impacts; and (iv) consideration of the production volume and use/release patterns in determining regulatory data and testing requirements. Transitioning toward a toxic-free and sustainable circular economy will likely require additional policy instruments that will reduce the overall complexity and diversity of in-use polymers and polymeric materials.

Identifying persistent, mobile and toxic (PMT) organic compounds detected in shale gas wastewater.

Shale gas exploitation is a water-intensive process, generating flowback and produced water (FPW) with complex chemical compositions. Reuse, disposal and treatment of FPW are of increasing concern, because of the potential risk of FPW contamination to the surrounding aquatic environment and drinking water sources when emitted. Among numerous organic substances present in FPW, of particular concern are those that are persistent, mobile and toxic (PMT) and very persistent and very mobile (vPvM). PMT and vPvM substances have the greatest potential to spread in groundwater and are the hardest to remediate. This study presents the outcome of a literature review to identify organic compounds that were previously detected in FPW. The 162 target compounds identified from this review were assessed to see if they can be considered PMT/vPvM substances based on their substance properties. Our results indicated that most FPW substances are "not PMT", accounting for 108 (66.7 %) compouds. In total 22 FPW substances can be considered PMT/vPvM or very likely to meet this criteria if more data were available. Examples of PMT substances in FPW include anthracene, 1,4-dioxane and 1,4-dichlorobenzene. PMT/vPvM compounds identified in FPW should be prioritized for risk management measures and monitoring in order to protect regional water resources.

Sewage sludge biochars as effective PFAS-sorbents.

The use of sewage sludge to produce biochar-based sorbents for per- and polyfluoroalkyl substances (PFAS) removal from water and soil may be an economically and environmentally sustainable waste management option. This study compared the sorption of six perfluorinated carboxylic acids (PFCAs) by two sewage sludge biochars (SSBCs) and one wood chip biochar (WCBC), dry pyrolyzed at 700 °C. Batch sorption tests were conducted by adding individual PFCAs and a PFCA-mixture to pure biochars and mixtures of biochar and a sandy soil (1.3% TOC). PFAS-sorption to the SSBCs exhibited log-linear biochar-water distribution coefficients (log Kd), comparable to those previously reported for commercial activated carbons (e.g., 5.73 ± 0.02 for perfluorooctanoic acid at 1 µg/L). The strong sorption of PFCAs was attributed to the SSBCs relatively high pore volumes in the pore size range that can accommodate these compounds. Sorption was attenuated by the presence of soil (by factors 3-10), by the presence of a mixture of PFCAs (by factors of 6-532) and by both together (by factors of 8-6581), indicating strongly competitive sorption between PFCA-congeners, and less severe sorption attenuation by soil organic matter. These findings could enable sustainable value chains for SSBs in soil remediation and water filtration solutions.

Assessing the Persistence and Mobility of Organic Substances to Protect Freshwater Resources.

Persistent and mobile organic substances are those with the highest propensity to be widely distributed in groundwater and thereby, when emitted at low-levels, to contaminate drinking water extraction points and freshwater environments. To prevent such contamination, the European Commission is in the process of introducing new hazard classes for persistent, mobile, and toxic (PMT) and very persistent and very mobile (vPvM) substances within its key chemical regulations CLP and REACH. The assessment of persistence in these regulations will likely be based on simulated half-life, t 1/2, thresholds; the assessment of mobility will likely be based on organic carbon-water distribution coefficient, K OC, thresholds. This study reviews the use of t 1/2 and K OC to describe persistence and mobility, considering the theory, history, suitability, data limitations, estimation methods, and alternative parameters. For this purpose, t 1/2, K OC, and alternative parameters were compiled for substances registered under REACH, known transformation products, and substances detected in wastewater treatment plant effluent, surface water, bank filtrate, groundwater, raw water, and drinking water. Experimental t 1/2 values were rare and only available for 2.2% of the 14 203 unique chemicals identified. K OC data were only available for a fifth of the substances. Therefore, the usage of alternative screening parameters was investigated to predict t 1/2 and K OC values, to assist weight-of-evidence based PMT/vPvM hazard assessments. Even when considering screening parameters, for 41% of substances, PMT/vPvM assessments could not be made due to data gaps; for 23% of substances, PMT/vPvM assessments were ambiguous. Further effort is needed to close these substantial data gaps. However, when data is available, the use of t 1/2 and K OC is considered fit-for-purpose for defining PMT/vPvM thresholds. Using currently discussed threshold values, between 1.9 and 2.6% of REACH registered substances were identified as PMT/vPvM. Among the REACH registered substances detected in drinking water sources, 24-30% were PMT/vPvM substances.

The NORMAN Suspect List Exchange (NORMAN-SLE): facilitating European and worldwide collaboration on suspect screening in high resolution mass spectrometry.

Background: The NORMAN Association (https://www.norman-network.com/) initiated the NORMAN Suspect List Exchange (NORMAN-SLE; https://www.norman-network.com/nds/SLE/) in 2015, following the NORMAN collaborative trial on non-target screening of environmental water samples by mass spectrometry. Since then, this exchange of information on chemicals that are expected to occur in the environment, along with the accompanying expert knowledge and references, has become a valuable knowledge base for "suspect screening" lists. The NORMAN-SLE now serves as a FAIR (Findable, Accessible, Interoperable, Reusable) chemical information resource worldwide. Results: The NORMAN-SLE contains 99 separate suspect list collections (as of May 2022) from over 70 contributors around the world, totalling over 100,000 unique substances. The substance classes include per- and polyfluoroalkyl substances (PFAS), pharmaceuticals, pesticides, natural toxins, high production volume substances covered under the European REACH regulation (EC: 1272/2008), priority contaminants of emerging concern (CECs) and regulatory lists from NORMAN partners. Several lists focus on transformation products (TPs) and complex features detected in the environment with various levels of provenance and structural information. Each list is available for separate download. The merged, curated collection is also available as the NORMAN Substance Database (NORMAN SusDat). Both the NORMAN-SLE and NORMAN SusDat are integrated within the NORMAN Database System (NDS). The individual NORMAN-SLE lists receive digital object identifiers (DOIs) and traceable versioning via a Zenodo community (https://zenodo.org/communities/norman-sle), with a total of > 40,000 unique views, > 50,000 unique downloads and 40 citations (May 2022). NORMAN-SLE content is progressively integrated into large open chemical databases such as PubChem (https://pubchem.ncbi.nlm.nih.gov/) and the US EPA's CompTox Chemicals Dashboard (https://comptox.epa.gov/dashboard/), enabling further access to these lists, along with the additional functionality and calculated properties these resources offer. PubChem has also integrated significant annotation content from the NORMAN-SLE, including a classification browser (https://pubchem.ncbi.nlm.nih.gov/classification/#hid=101). Conclusions: The NORMAN-SLE offers a specialized service for hosting suspect screening lists of relevance for the environmental community in an open, FAIR manner that allows integration with other major chemical resources. These efforts foster the exchange of information between scientists and regulators, supporting the paradigm shift to the "one substance, one assessment" approach. New submissions are welcome via the contacts provided on the NORMAN-SLE website (https://www.norman-network.com/nds/SLE/). Supplementary Information: The online version contains supplementary material available at 10.1186/s12302-022-00680-6.