Rubber-related chemicals are widely used in tires and technical rubber products, but their occurrence in food remains poorly understood. This study analyzed 17 raw milk samples and rubber components from dairy production systems for benzothiazoles, guanidine accelerators, and p-phenylenediamine antioxidants. Four compounds (S-BTH, DPG, 6-PPD, and 6-PPD-Q) were detected in milk (38.8–26,258.5 ng/L), with at least one quantified in 41% of samples (7/17), whereas none of the target compounds were detected in the three samples collected from alpine farms. Fourteen rubber-related chemicals were identified in milk-contact rubber components (42.9 μg/g–3.7 mg/g). Solubilization experiments confirmed partial leaching, with released chemical profiles reflecting bulk material composition. These findings indicate that rubber-related chemicals can occur in raw milk and that both environmental sources and migration from food-contact materials represent potential contamination pathways. However, the limited sample size and absence of a clear relationship with road traffic intensity preclude identification of the predominant contamination source.

Tire wear particles (TWP) are produced due to abrasion and, consequently, deposited on the roadside where they are transferred to the surrounding soil and surface waters. Despite the growing interest on TWP and related chemicals' effects on aquatic organisms, their potential interaction with periphytic biofilm communities is not well understood. As these complex assemblages of microorganisms form the base of aquatic food webs, it is critical to assess the potential impact of tire particles to these communities. We used cryogenically milled tire tread (CMTT), as a surrogate for TWP, to (1) expose periphyton to four CMTT concentrations (0, 50, 500, 1000 mg/L) for 14 days, and (2) compare periphyton responses to CMTT particles (1000 mg/L) and associated chemicals in separate 4 day exposures. In both scenarios, about 25-30% of CMTT were found associated with the periphyton assemblage, illustrating its function as a sink. Additionally, photosynthetic efficiency decreased slightly at the highest tested concentration, 1000 mg/L, and/or associated chemicals, while algal biomass (chlorophyll a) at 14 days decreased ∼30% for 500 and 1000 mg/L CMTT. After the 14 days exposure, changes to the community structure and composition were detected for all CMTT concentrations. In particular, the bacteria phylum Bacillota became nearly absent in the presence of CMTT; similarly, diatom abundance decreased by 45, 85 and 70% at 50, 500, and 1000 mg/L CMTT compared to control, respectively. Consequently, other groups, such as Cyanobacteriota and green algae, became more abundant at higher CMTT concentrations. For the 4 days exposure, CMTT-related chemicals alone caused effects comparable to CMTT particles. Overall, this work highlights the importance of investigating periphyton community responses to TWP, as we show they are susceptible to tire-derived toxicity, while also influencing the fate and effects of tire particles and chemicals in aquatic environments.

The production of plastics is steadily increasing and raises major environmental and public health concerns. Those used every day, including in the medical sector, lead to the formation of microplastics (MP). These can then contaminate water, air, soil and our food. Through inhalation or ingestion, MP can enter the bloodstream and reach various organs. The presence of MP has also been demonstrated in the kidneys and urine. In vitro and animal studies suggest potential nephrotoxicity of MP. Patients with kidney diseases may be at increased risk due to higher exposure through medical procedures and reduced urinary elimination. Further studies are needed to clarify this risk.

Abstract Microplastics are widespread, yet methods to measure polymer type simultaneously and particles size smaller than 20 µm are limited, hindering toxicity assessment and policy formulations. We introduce a machine learning-assisted spectral flow cytometry approach that identifies six major polymers relevant to the environment and human health within the 5–100 µm range and allows projection in the 1–100 µm range. High-throughput, sensitive detection, straightforward sampling, and strong quality control make this technique suitable for routine monitoring of industrial and natural waters. Clear differences in microplastics levels and polymer composition were found between Lake Geneva, nearby rivers, and surface versus deep waters. With up to 97% of microplastics between 1 and 20 µm, data indicates a substantial underestimation of pollution. Consistent with laser-infrared measurements, concentrations of small-sized microplastics exceed previous reports in lake waters up to 656-fold. Environmental risk assessment of microplastics suggests that risk might be expected at some sampling sites.

Ecotoxicological indicators could be an important tool in soil monitoring programs to help understand the effects and ecotoxicity of potentially contaminated soils. For soil, one of the most complex environmental matrices, they can elucidate questions regarding the bioavailability of contaminants. However, the use of ecotoxicological indicators in retrospective risk assessment, in particular monitoring, struggles with the lack of adequate reference sites and/or responses. In this study we aim to define a reference or normal response range by evaluating the natural variability in soils of 4 ecotoxicological indicators species (Folsomia candida, Enchytraeus crypticus, Brassica napus, Allium cepa) including 3 endpoints (reproduction, shoot length and root length). Two approaches were used to establish the normal response range, one based on variability towards a control response (minimum detectable differences and maximum tolerable inhibition) and a percentile response based on the variability within the natural test soils. For this, 32 natural soils from the Jura region of Switzerland were tested with the 4 ecotoxicological indicators. To ensure responses were not driven by background chemical concentrations samples were analysed for metal concentrations, as regulated by Swiss legislation and for 144 pesticide residuess. Pesticides concentrations in the selected soils were very low and higher metals concentrations were mostly of geogenic origin and did not appear to influence biological responses. Regarding biological variability, it was possible to determine normal operating ranges for all four ecotoxicological test species, and the percentile approach seems better suited for natural soils from the Jura region, for which LUFA 2.2 is not always very representative. The percentile approach shows a high potential as a methodology for setting reference response ranges based on the natural variability in soils. The approach now needs to be compared to potentially contaminated soils and extended to other biogeochemical regions to allow its use in monitoring programs.

Global concerns regarding microplastics emerging in the environment have been raised recently. Using samples collected during the OceanXplorer mission in Aqaba, we explored the depth-based and regional variations of microplastics across pelagic and benthic zones. Microplastics (63.0-950.0 mu m) from the surface seawater, middle seawater, bottom seawater, and deep-sea sediment were quantified and identified using a dissecting microscope and Fourier Transform Infrared microscope (mu-FTIR). The results revealed that the average abundance of microplastics was 6.7 +/- 6.05 particles L-1 in the pelagic zone and 2900 +/- 1650 particles kg-1 in the benthic zone. A size gradation of microplastics was observed across depths from 5 to 840 m, accompanied by a shift in particle types: fragments were the most common in the benthic zone, whereas fibers dominated the pelagic zone. mu-FTIR analysis identified the presence of the following polymers: polyethylene (PE), polyvinyl chloride (PVC), polyamide 6 (PA 6), and polypropylene (PP). These findings establish baseline data for future monitoring and management efforts addressing microplastic pollution in the Gulf of Aqaba.

There is increasing research focused on rubber additives, predominantly originating from tire and road wear particles. Other consumer products including sports equipment also contain rubber additives and the overall human exposure to these compounds is of concern due to demonstrated toxicity to animal species. Rubber additives are intentionally incorporated into climbing shoes for specific performance. We found high concentrations of rubber additives in shoe sole samples, aerosol particulate matter, and settled dust in indoor climbing halls. The estimated daily intake via inhalation for climbers and employees of these facilities exceeds the intake of rubber additives from all other known sources. Abrasion powder resulting from friction of climbing shoes on the holds is responsible for the high concentrations of rubber additives observed in aerosol particulate matter and settled dust, while other emission sources could be excluded. We also show that atmospheric transformation of rubber additives occurs in indoor environments. These findings identify a previously unknown human exposure route to rubber additives and emphasize the global problem of the toxicity burden of plastic additives.

Tire wear particles, released at an estimated 6 million tons annually worldwide, introduce various chemical substances into agricultural environments through atmospheric deposition, road runoff, and reclaimed wastewater. These tire-derived compounds are known to impact ecosystem health. This study investigates the transfer of such additives and their metabolites into vegetables, assessing human dietary intake. Using UPLC-MS/MS, eleven tire-related compounds were analyzed in 100 vegetable samples from nine Swiss retailers, including leafy (lettuce, cabbage, spinach), root (onion, potato, carrot), and fruit (tomato, bell pepper, zucchini, pumpkin) vegetables. Contamination was detected in all vegetable varieties. 31 % of the 100 samples contained benzothiazole (BTH), 1,3-diphenylguanidine (DPG), 6-PPD, or 1,3-dicyclohexylurea (DCU) at levels exceeding the limit of quantification (LOQ) whereas blank values remained below LOD. DPG was most frequently detected (18 %, n = 100), followed by 6-PPD (15 %, n = 100), DCU (10 %, n = 100), and BTH (3 %, n = 100). Spinach comprised 78 % of DPG-positive leafy samples. Daily intakes of 6-PPDQ, DCU, 6-PPD, and DPG from vegetables were estimated at 0-18.7, 0-57.7, 0-42.3, and 0-42.4 ng/person/day, respectively. While current toxicological data suggest no immediate health concerns, significant knowledge gaps remain regarding long-term toxicity. This study offers critical insights into the presence of tire-derived substances in agriculture and underscores the need for further research to better assess environmental and human health risks.

Pollution from past industrial activities can remain unnoticed for years or even decades because the pollutant has only recently gained attention or been identified by measurements. Modeling the emission history of pollution is essential for estimating population exposure and apportioning potential liability among stakeholders. This paper proposes a novel approach for reconstructing the history of polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) pollution from municipal solid waste incinerators (MSWIs) with unknown past emissions. The proposed methodology relies on the search for technical and operational data on the pollution source in archives, the extraction of representative data from the scientific literature, and the use of kinetic models of the formation and decomposition of PCDD/Fs within combustion chambers. This new methodological tool allows to estimate any MSWI's stack emission and relative profile of seventeen PCDD/F congeners over time. The approach is validated through a case study of an MSWI in Switzerland. The modeled congener profile achieved a Pearson correlation coefficient of 0.98 with measurements in fly ash washwater. Additionally, the simulated soil quantity (1,115-1,419 gTEQ WHO-2005 or 1,283-1,698 gTEQWHO-2022) agrees in order of magnitude with the estimated quantity from measurements (371 gTEQ WHO-2005 or 425 gTEQ WHO-2022).

There is a growing interest in the development of reliable analytical methods for characterizing tire and road wear particles (TRWP). The current research extends the use of single particle analysis techniques to various experimental biota samples. TRWP and cryogenically milled tire tread (CMTT) were identified using a weight of evidence framework including density separation, optical microscopy, and chemical mapping (scanning electron microscopy coupled with energy dispersive X-ray spectroscopy). Our techniques successfully identified CMTT particles in laboratory earthworms exposed to soil spiked with CMTT. A river biota sample (bivalves) collected from the Seine with no detectable TRWP was spiked with road dust containing TRWP. Particle identification was performed after a biota digestion protocol and density separation of particles > 1.5 g/cm3 and < 2.2 g/cm3 which resulted in sufficient TRWP for identification and characterization. The average TRWP particle size from the road dust spiked biota sample was 126 μm by number and 220 μm by volume (range: 9 -572 μm). The size distribution overlay of TRWP identified from spiked biota were consistent with TRWP identified from the original road dust sample suggesting that the current method for biota digestion, dual density separation, and TRWP characterization is feasible for similar samples.

Tread wear emission inventories, uncertainty about the future development of the emissions and observed adverse effects of tire constituents in the environment have raised the need for an environmental risk assessment of tire wear emissions. While progress has been made in exposure and hazard assessment of tire wear emissions in the environment, the complexity of tire wear emissions creates some challenges which are not yet overcome. For instance, there is no universal agreed risk assessment framework for tire wear emissions. It was proposed that existing frameworks, for example for microplastics, be adapted to tire wear emissions because there are similarities between particulate tire wear emissions and microplastics, e.g. particulate material with a polymer backbone. The review discusses whether these are applicable for tire wear emissions and proposes adaptations. It provides a comprehensive assessment of exposure and hazard data for tire wear emission and reveals needs and data gaps for environmental risk assessment of tire wear. Based on the available exposure and hazard data sets a low risk prioritization of particulate tire wear emissions in aquatic and terrestrial environments was estimated. Risk prioritization of leachables from tire emissions is not yet possible due to inconsistent hazard data sets. It was found that for environmental risk assessment, insufficient consistent exposure and hazard data is available. It is suggested to develop clear harmonization guidelines how exposure and hazard studies should be designed. Such guidelines should be developed between all relevant stakeholders covering the entire product life cycle.

Tire and Road Wear Particles (TRWP) are produced during the wear of tire rubber on the road pavement and contain various chemicals originating from the road environment and from the rubber. Toxic effects of TRWP and their associated chemicals on soil organisms remain poorly characterized. In a series of laboratory experiments, this study investigated the bioaccumulation kinetics of several common tire-related chemicals in the earthworm species Eisenia andrei using Cryogenically Milled Tire Tread (CMTT), as a surrogate for environmental TRWP. Effects on survival, growth, reproductive output and behaviour were determined. Average biota-soil accumulation factors ranged from 0.8 to 4.7 indicating low to moderate bioaccumulation of the tire-related chemicals. Toxicokinetics showed both high uptake (0.0-13.2 days-1) and elimination rates (0.0-6.3 days-1) in E.andrei. Still, the uptake of tire-related chemicals in earthworms' tissues and ingestion of tire particles could lead to trophic transfer to preys feeding on earthworms and requires further investigated. No significant effects on survival and growth were recorded after exposure to 0.05 and 5% CMTT. In the reproduction test, a slight increase of the reproductive output with increasing CMTT concentration and a slight decrease of the weight of the juveniles were observed. Moreover, a strong and significant avoidance behaviour was observed for worms exposed to 5% CMTT. This work highlights that soil highly contaminated with tire particles can negatively impact habitat function due to changes in texture and/or chemical stressors, lead to uptake of tire-related additives by earthworms and that high concentrations can impact organism's fitness.

Tire and road wear particles (TRWP) contain complex mixtures of chemicals and release them to the environment, and potential toxic effects of these chemicals still need to be characterized. We used a standardized surrogate for TRWP, cryogenically milled tire tread (CMTT), to isolate and evaluate effects of tire‐associated chemicals. We examined organic chemical mixtures extracted and leached from CMTT for the toxicity endpoints genotoxicity, estrogenicity, and inhibition of bacterial luminescence. The bioassays were performed after chromatographic separation on high‐performance thin‐layer chromatography (HPTLC) plates. Extracts of CMTT were active in all three HPTLC bioassays with two estrogenic zones, two genotoxic zones, and two zones inhibiting bacterial luminescence. Extracts of CMTT artificially aged with thermooxidation were equally bioactive in each HPTLC bioassay. Two types of aqueous leachates of unaged CMTT, simulating either digestion by fish or contact with sediment and water, contained estrogenic chemicals and inhibitors of bacterial luminescence with similar profiles to those of CMTT extracts. Of 11 tested tire‐associated chemicals, two were estrogenic, three were genotoxic, and several inhibited bacterial luminescence. 1,3‐Diphenylguanidine, transformation products of N‐(1,3‐dimethylbutyl)‐N′‐phenyl‐p‐phenylenediamine, and benzothiazoles were especially implicated through comparison to HPTLC retention factors in the CMTT samples. Other bioactive bands in CMTT samples did not correspond to any target chemicals. Tire particles clearly contain and can leach complex mixtures of toxic chemicals to the environment. Although some known chemicals contribute to estrogenic, genotoxic, and antibacterial hazards, unidentified toxic chemicals are still present and deserve further investigation. Overall, our study expands the understanding of potential adverse effects from tire particles and helps improve the link between those effects and the responsible chemicals. Environ Toxicol Chem 2024;00:1–11. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

N-Nitrosamines are potential human carcinogens frequently detected in natural and engineered aquatic systems. This study sheds light on the role of carbonyl compounds in the formation of N-nitrosamines by nitrosation of five secondary amines via different pathways. The results showed that compared to a control system, the presence of formaldehyde enhances the formation of N-nitrosamines by a factor of 5-152 at pH 7, depending on the structure of the secondary amines. Acetaldehyde showed a slight enhancement effect on N-nitrosamine formation, while acetone and benzaldehyde did not promote nitrosation reactions. For neutral and basic conditions, the iminium ion was the dominant intermediate for N-nitrosamine formation, while carbinolamine became the major contributor under acidic conditions. Negative free energy changes (<-19 kcal mol-1) and relatively low activation energies (<18 kcal mol-1) of the reactions of secondary amines with N2O3, iminium ions with nitrite and carbinolamines with N2O3 from quantum chemical computations further support the proposed reaction pathways. This highlights the roles of the iminium ion and carbinolamine in the formation of N-nitrosamines during nitrosation in the presence of carbonyl compounds, especially in the context of industrial wastewater.

Nanoplastics (NPs) are released into surface water due to the widespread use of plastics, undergoing aging from environmental and human factors that alter their physical and chemical characteristics. However, detecting NPs remains challenging, resulting in limited research on their behavior in surface water and their removal efficiency by drinking water treatment. This study utilizes palladium-doped polystyrene nanoplastics (PSNPs) as tracers to enable precise detection and quantification through ICP-MS, thereby overcoming the limitations of conventional detection methods. PSNPs are aged using solar irradiation and ozone to simulate both natural and artificial aging processes, affecting the physical and chemical properties of NPs, which in turn influence their behavior in water treatment systems. Moreover, the study investigates the impact of various coagulation conditions, including different coagulants (AlCl3 and PACl), pH levels (4-9), and humic acid (HA) concentrations (0-10 mg/L), on the of both aged and nonaged NPs. The results demonstrate solar aging triggers significant morphological changes in PSNPs, while ozone aging induces more oxygen functional groups on PSNPs (CIozone=20.99; CIsolar=0.70), increasing sensitivity to HA concentrations and resulting in reduced removal efficiencies for ozone aged PSNPs by AlCl3 (68.68 %) and PACl (74.74 %). In addition, PACl achieves higher PSNPs removal efficiencies (REmin=88.59 %) than that of AlCl3 (REmin=85.57 %) under varied pH levels. This research fills a gap in understanding aged NPs behavior in surface water and offers practical solutions for optimizing coagulation for NPs removal, enhancing our ability to predict NPs environmental fate and manage NPs pollution to ensure drinking water safety.

This work presents the changing abundance of surface functional groups (SFGs) on polystyrene (PS) upon weathering within one or a few molecular monolayers from a molecular point of view. PS particles were aged by exposing it to a gas flow of typically (5 %) O3 in O2 (PSO3), UV radiation using a solar simulator under controlled conditions in the laboratory (PSSS) and to the water/air interface immerged in a freshwater lake for 2 months (PSL). The chemical composition of the interface of weathered, compared to pristine (virgin or PSV) material was established using a titration technique that probed the chemical composition of the molecular interface of the polymer. The main conclusions of this exploratory study are: (a) The interface of PS changes significantly compared to ATR-FTIR spectra that do not show additional absorptions in the mid-IR spectrum over a penetration depth of more than hundred monolayers at 10 μm; (b) The average surface functionalization of the gas-solid interface, corresponding to the sum of all examined types of SFG, increases from 20 % of a monolayer for PSV to 40, 50 and 84 % for PSL, PSO3 and PSSS, respectively; (c) in all cases the most important SFG was surface -OH ranging from 11.2 to 64 % for PSV and PSSS, respectively; (d) each PS sample shows a characteristic SFG pattern or fingerprint using several probe gases; (e) O3 interaction led to interface acidification; (f) UV treatment leads to the highest degree of surface -OH functionalization compared to PSO3 and PSL. The accumulation of SFG's renders the interface more reactive towards adsorption of probe gases.

Direct and indirect photolysis are important abiotic processes in aquatic environments through which plastics can be transformed physically and chemically. Transport of biodegradable plastics in water is influenced by vertical mixing and turbulent flow, which make biodegradable plastics remain susceptible to sunlight and photolysis despite their high density. In general, biodegradable plastics are composed of ester containing polymers (e.g., poly(butylene succinate), polyhydroxyalkanoate, and polylactic acid), whereas non-biodegradable plastics are composed of long chains of saturated aliphatic hydrocarbons in their backbones (e.g., polyethylene, polypropylene, and polystyrene). Based on the reviewed knowledge and discussion, we may hypothesize that 1) direct photolysis is more pronounced for non-biodegradation than for biodegradable plastics, 2) smaller plastics such as micro/nano-plastics are more prone to photodegradation and photo-transformation by direct and indirect photolysis, 3) the production rate of reactive oxygen species (ROS) on the surface of biodegradable plastics is higher than that of non-biodegradable plastics, 4) the photodegradation of biodegradable plastics may be promoted by ROS produced from biodegradable plastics themselves, and 5) the subsequent reactions of ROS are more active on biodegradable plastics than non-biodegradable plastics. Moreover, micro/nanoplastics derived from biodegradable plastics serve as more effective carriers of organic pollutants than those from non-biodegradable plastics and thus biodegradable plastics may not necessarily be more ecofriendly than non-biodegradable plastics. However, biodegradable plastics have been largely unexplored from the viewpoint of direct or indirect photolysis. Roles of reactive oxygen species originating from biodegradable plastics should be further explored for comprehensively understanding the photodegradation of biodegradable plastics.

Microplastics, especially aged microplastics can become vectors of heavy metals from environment to organisms with potential negative effects on food chain. However, a few studies focused on the bioavailability of adsorbed metals and most studies related to aged microplastics used artificial method that cannot entirely reflect actual aging processes. In this study, virgin polystyrene was aged by ozone (PS-O3), solar simulator (PS-SS) and lake (PS-Lake) to investigate adsorption of Cu by virgin, artificially and naturally aged microplastics and subsequent release in simulated gastrointestinal fluids (SGF). Characterization results show carbonyl was formed in PS-O3 and PS-SS, and the oxidation degree was PS-O3> PS-SS> PS-Lake. However, Cu adsorption capacity followed this order PS-Lake (158 μg/g)> PS-SS (117 μg/g)> PS-O3 (65 μg/g)> PS-Virgin (0). PS-O3 showed highest Cu adsorption capacity at 0.5 h (71 μg/g), but it dropped dramatically later (10 μg/g, 120 h), because PS-O3 could break up and the adsorbed Cu released in solutions subsequently. For PS-Lake, precipitation of metallic oxides contributes to the accumulation of Cu. The addition of dissolved organic matter (DOM) could occupy adsorption sites on PS and compete with Cu, but also can attach PS and adsorb Cu due to its rich functional groups. The simultaneous ingestion of microplastics with food suggested that adsorbed Cu is solubilized mostly from aged PS to SGF.

Humans are chronically exposed to airborne microplastics (MPs) by inhalation. Various types of polymer particles have been detected in lung samples, which could pose a threat to human health. Inhalation toxicological studies are crucial for assessing the effects of airborne MPs and for exposure-reduction measures. This communication paper addresses important health concerns related to MPs, taking into consideration three levels of complexity, i.e., the particles themselves, the additives present in the plastics, and the exogenous substances adsorbed onto them. This approach aims to obtain a comprehensive toxicological profile of deposited MPs in the lungs, encompassing local and systemic effects. The physicochemical characteristics of MPs may play a pivotal role in lung toxicity. Although evidence suggests toxic effects of MPs in animal and cell models, no established causal link with pulmonary or systemic diseases in humans has been established. The transfer of MPs and associated chemicals from the lungs into the bloodstream and/or pulmonary circulation remains to be confirmed in humans. Understanding the toxicity of MPs requires a multidisciplinary investigation using a One Health approach.