Benzotriazole-type ultraviolet stabilizers and antioxidants in plastic marine debris and their new products

Source traceability of microplastics in road dust using organic/inorganic plastic additives as chemical indicators

Microplastics (MPs) are environmental pollutants of great concern around the world. The source of MPs in road dust need to be identified to develop strategies to control and reduce MPs emissions by stormwater runoff, one of the main sources of MPs to the aquatic environment. However, little information on the sources of MPs in road dust is available due to lack of their suitable indicators. In this study organic/inorganic plastic additives were used as chemical indicators to understand the source of MPs in road dust. The polymers, organic additives, and heavy metals in 142 commercial plastic products suspected of being source of MPs in road dust were determined. As the results, 147 organic additives and 17 heavy metals were identified, and different additive profiles were found for different polymer types and use application of plastic products. Further, 17 road dust samples were collected from an urban area in Kumamoto City, Japan. and analyzed the MPs (1-5 mm diameter) and their additive chemicals. Polymethyl methacrylate (PMMA) was the dominant polymer accounting for 86 % in the samples, followed by ethylene vinyl acetate (EVA) and polyvinyl chloride (PVC). In total, 48 organic additives and 14 heavy metals were identified in the MPs samples. The organic/inorganic additive profiles of plastic products and MPs in road dust were compared, and several road dust-associated MPs had similar additive profiles to road paints, braille blocks, road marking sheets, and reflectors. This suggested that the MPs were originated from these plastics on the road surface. Road paint was the most important contributor of MPs in road dust (60 % of the MPs), followed by braille block (23 %), road marking sheet (8.3 %), and reflector (2.4 %). These results indicated that organic/inorganic plastic additives in plastic products can be used as chemical indicators to trace the sources of MPs in road dust.

Contamination of ultraviolet absorbers in food: toxicity, analytical methods, occurrence and risk assessments

Ultraviolet (UV) absorbers are chemical substances that are widely used as defenses against the damaging effects of solar radiations. UV absorbers, despite their benefits, are categorized as emerging pollutants because they have been demonstrated to be mutagenic, toxic, pseudo-persistent, bio-accumulative, and to have strong estrogenic effects. Because of their common use in personal care products, they continue to enter the environment. Several food samples, particularly those derived from aquatic sources, have been found to be contaminated with these compounds. Toxic effects on aquatic life, such as metabolic imbalance and developmental toxicity, result from the continued presence of UV absorbers in aquatic bodies. In addition, the degree of exposure to these pollutants in foods should be examined because there are certain risks associated with their consumption by humans. Therefore, this review focuses on the toxicity, analytical techniques, occurrence, and risk assessments of UV absorbers found in food.

Bisphenol A sorption on commercial polyvinyl chloride microplastics: Effects of UV-aging, biofilm colonization and additives on plastic behaviour in the environment

Chemical additives are important components in commercial microplastics and their leaching behaviour has been widely studied. However, little is known about the potential effect of additives on the adsorption/desorption behaviour of pollutants on microplastics and their subsequent role as vectors for pollutant transport in the environment. In this study, two types of commercial polyvinyl chloride (PVC1 and PVC2) microplastics were aged by UV irradiation and biotic modification via biofilm colonization to investigate the adsorption and desorption behaviour of bisphenol A (BPA). Surface cracks and new functional groups (e.g., O-H) were found on PVC1 after UV irradiation, which increased available adsorption sites and enhanced H‒bonding interaction, resulting in an adsorption capacity increase from 1.28 μg/L to 1.85 μg/L. However, the adsorption and desorption capacity not showed significant changes for PVC2, which might be related to the few characteristic changes after UV aging with the protection of light stabilizers and antioxidants. The adsorption capacity ranged from 1.28 μg/L to 2.06 μg/L for PVC1 and PVC2 microplastics, and increased to 1.62 μg/L-2.95 μg/L after colonization by biofilms. The increased adsorption ability might be related to the N-H functional group, amide groups generated by microorganisms enhancing the affinity for BPA. The opposite effect was observed for desorption. Plasticizers can be metabolized during biofilm formation processes and might play an important role in microorganism colonization. In addition, antioxidants and UV stabilizers might also indirectly influence the colonization of microorganisms' on microplastics by controlling the degree to which PVC microplastics age under UV. The amount of biomass loading on the microplastics would further alter the adsorption/desorption behaviour of contaminants. This study provides important new insights into the evaluation of the fate of plastic particles in natural environments.

Prevalence of synthetic phenolic antioxidants in food contact materials from China and their implications for human dietary exposure through take-away food

The application of disposable tableware has increased substantially in recent times due to the rapidly growing food delivery business in China. Synthetic phenolic antioxidants (SPAs) are widely used in food contact materials (FCMs) to delay the process of oxidation; however, their compositions, concentrations, and potential health hazards remain unclear. Therefore, FCMs comprised of five materials obtained from 19 categories (n = 118) in China were analyzed for SPAs concentrations. FCMs have been found to contain a variety of SPAs, with ∑SPAs concentrations ranging from 44.18 to 69,485.12 μg/kg (median: 2615.63 μg/kg). The predominant congeners identified in the sample include 2,4-di-tert-butylphenol (2,4-DTBP), 2,6-di-tert-butylphenol (2,6-DTBP), and 2,6-di-tert-butyl-p-benzoquinone (BHT-Q) with a median concentration of 885.75, 555.45 and of 217.44 μg/kg, respectively. Milky tea paper cups, instant noodle buckets, milky teacups, and disposable cups showed high levels of SPAs. 2,2'-methylenebis(4-methyl-6-tert-butylphenol) (AO 2246) was predominantly detected in polyethylene and polyethylene terephthalate-based products. The migration test identified disposable plastic cups and bowls as the predominant FCMs and 2,4-DTBP as the dominant SPA. The exposure risk of SPAs decreased with age. In children, the estimated daily intake of ∑SPAs from FCMs was determined to be 17.56 ng/kg body weight/day, which was 8.3 times higher than that of phthalic acid esters. The current findings indicate the potential ingestion risk of SPAs during the daily life application of multiple FCM categories.

Revealing chemical release from plastic debris in animals' digestive systems using nontarget and suspect screening and simulating digestive fluids

Plastic debris in the environment are not only pollutants but may also be important sources of a variety of contaminants. This work simulated kinetics and potential of chemical leaching from plastic debris in animals' digestive systems by incubating polyvinyl chloride (PVC) cord particles in artificial digestive fluids combined with nontarget and suspect screening based on UHPLC-Orbitrap HRMS. Impacts of particle size, aging, and digestive fluid were investigated to elucidate mechanisms of chemical leaching. Thousands of chemical features were screened in the leachates of PVC cord particles in the artificial digestive fluids, among which >60% were unknown. Bisphenol A (BPA) and bis(2-ethylhexyl) phthalate (DEHP) were the dominant identified CL1 compounds. Finer size and aging of the PVC particles and prolonged incubation time enhanced chemical release, resulting in greater numbers, higher levels, and more complexity in components of the released chemicals. The gastrointestinal fluid was more favorable for chemical leaching than the gastric fluid, with greater numbers and higher levels. Hundreds to thousands of chemical features were screened and filtered in the leachates of consumer plastic products, including food contact products (FCPs) in the artificial bird gastrointestinal fluid. In addition to BPA and DEHP, several novel bisphenol analogues were identified in the leachate of at least one FCP. The results revealed that once plastic debris are ingested by animals, hundreds to thousands of chemicals may be released into animals' digestive tracts in hours, posing potential synergistic risks of plastic debris and chemicals to plastic-ingesting animals. Future research should pay more attentions to identification, ecotoxicities, and environmental fate of vast amounts of unknown chemicals potentially released from plastics in order to gain full pictures of plastic pollution in the environment.

Uptake, accumulation and metabolism of UV-320 in vegetables and its impact on growth and quality

UV-320 is classified as a Substance of Very High Concern (SVHC) by the European Chemicals Agency and has attracted significant attention due to its presence in the environment. Understanding the uptake, translocation and metabolic patterns of UV-320 in vegetables is essential for assessing their ability to bioaccumulate and potential risks to human health. In this study, we investigated the uptake and translocation of UV-320 in lettuce and radish by hydroponic experiments. The results showed that the root concentration factors (Croot/Csolution, RCF) of lettuce and radish were in the range of 47.9 to 464 mL/g and 194 to 787 mL/g, respectively. The transfer factors (Cshoot/Croot, TF) were observed to be 0.001-0.012 for lettuce and 0.02-0.05 for radish. Additionally, non-targeted screening identified twelve phase I and one phase II metabolites of UV-320 in vegetables, which were confirmed based on their molecular formulas and structures. The metabolic pathways involving oxidation, ketonylation and deamination were proposed in vegetables. Also, we have observed that UV-320 inhibits the growth of vegetables. Meanwhile, we evaluated the health risk of UV-320 in lettuce and radish and found that the consumption of lettuce is relatively safe, while the consumption of radish has a risk of HQ >1 for both adults and children, which should be seriously considered. This study provides valuable insights into the behavior and ecological risks of UV-320 in the environment.

Dissolution-precipitation method concatenated sodium alginate/MOF-derived magnetic multistage pore carbon magnetic solid phase extraction for determination of antioxidants and ultraviolet stabilizers in polylactic acid food contact plastics

Antioxidants and UV stabilizers have some endocrine disrupting effects and liver toxicity. Both types of additives are still widely used in food contact plastics to improve the durability of plastic products. However, efficient and rapid detection of antioxidants and UV stabilizers has been a challenge due to the complexity of the plastic matrix and the low content of antioxidants and UV stabilizers. In this study, a sodium alginate/MOF-derived magnetic multistage pore carbon material (MIL-101(Fe)/SA-CAs) was developed, having the merits of abundant multistage pore structure, large specific surface area, and good magnetic separation properties. Thus, this material was selected as the sorbent for magnetic solid-phase extraction combined with a dissolution-precipitation method for the extraction and purification of antioxidants and UV stabilizers from polylactic acid food contact plastics. The extraction parameters such as sorbent type, sorbent dosage, sample solution pH, ionic strength, sorption time, elution solution type, volume, and time were investigated. Under the optimized conditions, all the analytes determined by UPLC-MS/MS showed good linear range (r > 0.99), detection limit (0.023-3.105 ng g-1), accuracy (70.6-102.3 %), and reproducibility (RSD<9.8 %). Further, the developed method was applied to determine the antioxidants and UV stabilizers in polylactic acid lunch boxes and straws, showing excellent applicability. The results showed that the antioxidants and UV stabilizers were detected in some of the samples, with a maximum detection of antioxidant 1010 at 7297 ng g-1. This study provided a sensitive, efficient, and environmentally friendly method for antioxidants and UV stabilizers in polylactic acid food contact plastics. The ideas for the design of environmentally friendly metal-organic frameworks and biomass composite multifunctional materials would promise in the sample pretreatment field for the emerging contaminants.

Exposure to environmental levels of 2,4-di-tert-butylphenol affects digestive glands and induces inflammation in Asian Clam (Corbicula fluminea)

2,4-Di-tert-butylphenol (2,4-DTBP) is used as an antioxidant added to plastics. Due to its potential toxicity and relatively high concentrations in environments and presence in human tissue, concern has been raised for 2,4-DTBP as a contaminant associated with adverse health outcomes. However, studies on the toxicity of 2,4-DTBP are relatively limited, especially for benthic aquatic organisms. In this study, Asian clams (Corbicula fluminea) were exposed to environmentally relevant concentrations of 2,4-DTBP (0.01-1 μM, corresponding to 2.06-206.32 μg/L) for 21 days. Accumulation of 2,4-DTBP was noted in both gills and digestive glands, with the latter presenting as the primary target tissue. Increased damage rate of digestive tube and cellular DNA damage were observed in the digestive glands of 2,4-DTBP exposed clams. The injury was attributed to the imbalance of the antioxidant system, characterized by elevated oxidative stress and inflammation (upregulation of ROS, MDA, NO, and pro-inflammatory factors). In contrast, upon 2,4-DTBP exposure, antioxidant system in gills was activated, while ROS and NO were not promoted. Moreover, NF-κB and IL-1 were significantly decreased. These results suggested that biochemical mechanisms were activated in gills to maintain homeostasis. Internal exposure in the digestive gland was significantly correlated with the biochemical biomarkers tested, underscoring the potential risk associated with the bioaccumulation of 2,4-DTBP from contaminated environments. These findings provide novel insights into toxicity of 2,4-DTBP in bivalves, contributing valuable knowledge to risk assessment and chemical management.

Spatiotemporal variation, partitioning, and ecological risk assessment of benzothiazoles, benzotriazoles, and benzotriazole UV absorbers in the Yangtze River Estuary and its adjacent area

The distributions and toxicities of the pollutants benzothiazoles (BTHs), benzotriazoles (BTRs), and benzotriazole ultraviolet stabilizers (BUVs) have attracted much attention, but most research has focused on freshwater environments and few have examined their levels in marine environments. This study, for the first time, investigated the spatial and temporal variability and ecological risks of BTHs, BTRs and BUVs in the Yangtze River estuary and its adjacent area, and further elucidated how environmental factors influence the transport of these contaminants. The concentrations of BTHs, BTRs, and BUVs in seawater showed significant seasonal variability, with the highest concentrations in summer, followed by autumn, and then winter-spring. The spatiotemporal variability in BTHs, BTRs and BUVs in the seawater and sediments samples showed decreasing trends from nearshore to offshore, reflecting the influence of river discharge. Marine debris and continuous discharge from cities were responsible for the high detection frequency of these contaminants in the YRE and its adjacent area. Furthermore, the moderate risk from the presence of BTHs, BTRs, and BUVs as they accumulate in sediments should not be ignored. Our study provides new insights into the fate and ecological risk of BTHs, BTRs, and BUVs in the estuary.

Plastic protective nets: A significant but neglected "reservoir" for priority chemicals as revealed by composition analysis

As chemical-intensive products, plastics are potential sources of emerging contaminants and pose risks to the ecosystem. However, knowledge on the inventory and emissions of chemicals in plastics remains scarce, prohibiting the lifecycle assessment of their environmental exposure. Herein, full compositions of plastic protective nets (PPNs, one globally used plastics) were analyzed via nontarget screening with mass spectrometry, optical emission spectrometry, infrared spectroscopy and thermogravimetric analysis. Nontarget screening identified 861 non-polymeric organic chemicals, which were classified by network-like similarity analysis into 9 communities, dominated by phthalates (PAEs), aliphatic/oxalic esters and branched alkanes. Notably, around 80.8% (696) of the chemicals were first observed in plastics, suggesting aplenty plastic additives have previously been overlooked. Quantification results indicated PPNs contained higher levels of priority chemicals, including detrimental lead (1.17 × 104 ng/g), benzotriazoles ultraviolet stabilizers (6.66 × 103 ng/g) and PAEs (1.87 × 104 ng/g) than other plastics commonly reported. Emission projections revealed that dibutyl phthalate in PPNs had an annual release (1.83 × 103 kg) comparable to that from greenhouse films in China. These findings suggest PPNs are a significant but neglected "reservoir" for priority chemicals, which could inform future research on resolving plastic compositions, so as to promote sound chemical management.

Neurotoxicity of Benzotriazole Ultraviolet Stabilizers in Teleost Fishes: A Review

Plastic additives that maintain integrity have been extensively studied for potential toxicity to fish; however, chemicals that protect polymers from (artificial) UV degradation are less studied. Benzotriazole UV stabilizers (BUVSs) are the most widely used UV stabilizers in plastics and are often used in sunscreens, cosmetics, paint, and food packaging. BUVSs can negatively affect aquatic wildlife when released into the environment via plastic degradation. In this review, we summarize the distribution of BUVSs globally and discuss neurotoxicological endpoints measured in fish to understand how these plastic additives can affect the neurological health of teleost fishes. BUVSs have been detected in aquatic environments at concentrations ranging from 0.05 up to 99,200 ng/L. Studies show that BUVSs affect behavioral responses and acetylcholinesterase activity, indicators of neurotoxicity. Our computational analysis using transcriptome data suggests certain pathways associated with neurodegeneration are responsive to exposure to BUVSs, like "Complement Activation in Alzheimer's Disease". Based on our review, we identify some research needs for future investigations: (1) molecular studies in the central nervous system to define precise mechanisms of neurotoxicity; (2) a wider range of tests for assessing aberrant behaviors given that BUVSs can affect the activity of larval zebrafish; and (3) histopathology of the nervous system to accompany biochemical analyses. These data are expected to enhance understanding of the neurotoxicity potential of benzotriazoles and other plastic additives.

Exploring g-C3N4 as a green additive for biodegradable poly(butylene adipate-co-terephthalate) film with enhanced UV shielding and mechanical properties

Typical small organic dyes exhibit excellent UV absorption capabilities and are commonly used as additives to shield plastic films from photoaging. However, their tendency to decompose easily and migrate rapidly within a polymer matrix limits their service life. Herein we prepared g-C3N4 nanosheets and fabricated g-C3N4/PBAT films to investigate the effects of g-C3N4 on UV shielding and plasticizing of a biodegradable PBAT film. Photophysical characterizations revealed that an improved UV light barrier performance was achieved on g-C3N4/PBAT films compared to pure PBAT. Furthermore, the photoaging results show that g-C3N4 can stably exist in the PBAT matrix, enabling the aged g-C3N4/PBAT films to maintain their effective UV shielding ability, whereas the aged benzophenone (UV-0)/PBAT film shows a substantial decrease in UV light absorption due to the photodecomposition of UV-0. Additionally, g-C3N4 acted as a reinforcing material for PBAT, as evidenced by the approximately 1.5-fold increase in longitudinal tear strength and 1.6-fold increase in tensile strength of g-C3N4/PBAT films compared to pure PBAT. Remarkably, even after 100 hours of photoaging, the aged g-C3N4/PBAT films retained their favorable mechanical properties. This study highlights the potential of g-C3N4 as a new type of UV shield additive for future practical applications in protecting biodegradable plastic from photoaging.

Assessing the Toxicity of Benzotriazole Ultraviolet Stabilizers to Fishes: Insights into Aryl Hydrocarbon Receptor-Mediated Effects

Benzotriazole ultraviolet stabilizers (BUVSs) are chemicals used to mitigate UV-induced damage to manufactured goods. Their presence in aquatic environments and biota raises concerns, as certain BUVSs activate the aryl hydrocarbon receptor (AhR), which is linked to adverse effects in fish. However, potencies of BUVSs as AhR agonists and species sensitivities to AhR activation are poorly understood. This study evaluated the toxicity of three BUVSs using embryotoxicity assays. Zebrafish (Danio rerio) embryos exposed to BUVSs by microinjection suffered dose-dependent increases in mortality, with LD50 values of 4772, 11 608, and 56 292 ng/g-egg for UV-P, UV-9, and UV-090, respectively. The potencies and species sensitivities to AhR2 activation by BUVSs were assessed using a luciferase reporter gene assay with COS-7 cells transfected with the AhR2 of zebrafish and eight other fishes. The rank order of potency for activation of the AhR2 from all nine species was UV-P > UV-9 > UV-090. However, AhR2s among species differed in sensitivities to activation by up to 100-fold. An approximate reversed rank order of species sensitivity was observed compared to the rank order of sensitivity to 2,3,7,8-tetrachlorodibenzo[p]dioxin, the prototypical AhR agonist. Despite this, a pre-existing quantitative adverse outcome pathway linking AhR activation to embryo lethality could predict embryotoxicities of BUVSs in zebrafish.

Degradation kinetics and disinfection by-products formation of benzophenone-4 during UV/persulfate process

The degradation kinetics, reaction pathways, and disinfection by-products formation of an organic UV filter, benzophenone-4 (BP4) during UV/persulfate oxidation were investigated. BP4 can hardly be degraded by UV alone, but can be effectively decomposed by UV/persulfate following pseudo-first order kinetics. BP4 degradation rate was enhanced with increasing persulfate dosage and decreasing pH from 8 to 5. However, the degradation rate of BP4 at pH 9 was higher than that at pH 8 because of the presence of phenolic group in BP4 structure. and SO 4 - ⋅ were confirmed as the major contributors to BP4 decomposition in radical scavenging experiments, and the second-order rate constants between HO ⋅ and BP4 as well as those between SO 4 - ⋅ and BP4 were estimated by establishing and solving a kinetic model. The presence of B r - and humic acid inhibited the decomposition of BP4, while N O 3 - promoted it. The mineralisation of BP4 was only 9.1% at the persulfate concentration of 50 μM. Six degradation intermediates were identified for the promulgation of the reaction pathways of BP4 during UV/persulfate oxidation were proposed as a result. In addition, the formation of DBP in the sequential chlorination was evaluated at different persulfate dosages, pH values, and water matrix. The results of this study can provide essential knowledge for the effective control of DBP formation with reducing potential hazard to provide safe drinking water to the public.

UV filters in everyday cosmetic products, a comparative study

Today, UV filters are found as contaminants in a variety of biological fluids and environment, e.g. in vegetable crops and surface water. This is because UV filters are widely used in everyday products. In this context, we focused this study on cosmetic products, in order to assess the importance of this source of contamination. The study of 742 cosmetic products, excluding actual sunscreen products, but including hygiene, personal care and make-up products and perfumes revealed that the most common UV filters present are butyl methoxydibenzoylmethane (90 products or 12.1% of products tested), octyl methoxycinnamate (75 products or 10.1% of products tested), octocrylene (62 products or 8.3% of products tested), octyl salicylate (43 products or 5.8% of products tested) and titanium dioxide (33 products or 4.4% of products tested). Very few UV filters are found in the hygiene products (only in 12 shampoos/conditioners and in 2 shower gels) and deodorants and toothpastes are completely free of them. Conversely, make-up and perfumes are frequently formulated with at least one UV filter. Seventy-five of the two hundred and forty-four (or 30.7%) skincare products studied contained at least one UV filter. 49.1 of the makeup products studied and 74.3% of perfumes contained it.

Leaching of chemicals from microplastics: A review of chemical types, leaching mechanisms and influencing factors

It is widely known that microplastics are present everywhere and they pose certain risks to the ecosystem and humans which are partly attributed to the leaching of additives and chemicals from them. However, the leaching mechanisms remain insufficiently understood. This review paper aims to comprehensively and critically illustrate the leaching mechanisms in biotic and abiotic environments. It analyzes and synthesizes the factors influencing the leaching processes. It achieves the aims by reviewing >165 relevant scholarly papers published mainly in the past 10 years. According to this review, flame retardants, plasticizers and antioxidants are the three main groups of additives in microplastics with the potentials to disrupt endocrine functions, reproduction, brain development and kidney functions. Upon ingestion, the MPs are exposed to digestive fluids containing enzymes and acids which facilitate their degradation and leaching of chemicals. Fats and oils in the digestive tracts also aid the leaching and transport of these chemicals particularly the fat-soluble ones. Leaching is highly variable depending on chemical properties and bisphenols leach to a larger extent than other endocrine disrupting chemicals. However, the rates of leaching remain poorly understood, owing probably to multiple factors at play. Diffusion and partitioning are two main mechanisms of leaching in biotic and abiotic environments. Photodegradation is more predominant in the latter, generating reactive oxygen species which cause microplastic aging and leaching with minimal destruction of the chemicals leached. Effects of microplastic sizes on leaching are governed by Sherwood number, thickness of aqueous boundary layer and desorption half-life. This review contributes to better understanding of leaching of chemicals from microplastics which affect their ecotoxicities and human toxicity.

Leaching and transformation of chemical additives from weathered plastic deployed in the marine environment

Plastic pollution causes detrimental environmental impacts, which are increasingly attributed to chemical additives. However, the behaviour of plastic additives in the marine environment is poorly understood. We used a marine deployment experiment to examine the impact of weathering on the extractables profile, analysed by liquid chromatography-mass spectrometry, of four plastics at two locations over nine months in Aotearoa/New Zealand. The concentration of additives in polyethylene and oxo-degradable polyethylene were strongly influenced by artificial weathering, with deployment location and time less influential. By comparison, polyamide 6 and polyethylene terephthalate were comparatively inert with minimal change in response to artificial weathering or deployment time. Non-target analysis revealed extensive differentiation between non-aged and aged polyethylene after deployment, concordant with the targeted analysis. These observations highlight the need to consider the impact of leaching and weathering on plastic composition when quantifying the potential impact and risk of plastic pollution within receiving environments.

Floating plastics as integrative samplers of organic contaminants of legacy and emerging concern from Western Mediterranean coastal areas

This study investigates the role of floating plastics as integrative samplers of organic contaminants. To this end, plastics items were collected in two Western Mediterranean coastal areas: the Mar Menor lagoon, and the last transect of Ebro river. Floating plastics were identified and characterized by attenuated total reflection Fourier-transform infrared spectrometry. Then, organic contaminants were extracted from plastic items by ultrasonic extraction with methanol, and the concentrations of 168 regulated and emerging contaminants were analysed. These compounds were analysed by stir bar sorptive extraction coupled to gas chromatography-mass spectrometry (GC-MS), except for bisphenol analogues, which were analysed with a ultraperformance liquid chromatography pump coupled to a triple quadrupole mass spectrometer (UHPLC-MS/MS), and pharmaceutical compounds, determined by UPLC coupled to hybrid triple quadrupole-linear ion trap mass spectrometer (UPLC-MS/MS). All the contaminants groups considered were detected in the samples, being particularly relevant the contribution of plastic additives. The most frequently detected contaminants were UV-filters, PAHs, pharmaceuticals and synthetic musks. Apart from plasticizers, the individual contaminants octocrylene, homosalate, galaxolide, salycilic acid and ketoprofen were frequently detected in plastics items. The results pointed out to urban and touristic activities as the main sources of pollution in the coastal areas investigated. The utility of floating plastics as integrative samplers for the detection of organic contaminants in aquatic ecosystems has been demonstrated.

Effect of Mass Fraction on Leaching Kinetics of Hydrophobic Ultraviolet Stabilizers in Low-Density Polyethylene

The leaching kinetics of five hydrophobic ultraviolet (UV) stabilizers from low-density polyethylene (LDPE) (micro)fibers into water was evaluated in this study, with variation of the mass fraction (ω = 0.1-2.0 wt %) of the stabilizers. A one-dimensional convection-diffusion model for a cylindrical geometry, requiring partitioning between the LDPE fibers and water (KLDPEw) and the internal diffusion coefficients (DLDPE), was used to evaluate the leaching process and the leaching half-life of the target UV stabilizers at ω < 0.5 wt % (Case I). Diffusion through the aqueous boundary layer is the rate-determining step, and the leaching half-life is predicted to be very long (a few months to years) under unaffected conditions. When the UV stabilizers are supersaturated within LDPE fibers (i.e., ω > 0.5 wt %, Case II), the possible formation of a surficial crystal layer of the additives on the LDPE fiber extends the time scale for leaching compared to that in Case I due to the requirement of overcoming the crystallization energy. This study provides a fundamental understanding of the leaching profiles of plastic additives for assessing their potential chemical risks in aquatic environments; further studies under the relevant environmental conditions are required.

Airborne microplastics: A narrative review of potential effects on the human respiratory system

There has been growing evidence showing the widespread of airborne microplastics (AMPs) in many regions of the world, raising concerns about their impact on human health. This review aimed to consolidate recent literature on AMPs regarding their physical and chemical characteristics, deposition in the human respiratory tract, translocation, occurrence from human studies, and toxic effects determined in vitro and in vivo. The physical characteristics influence interactions with cell membranes, cellular internalization, accumulation, and cytotoxicity resulting from cell membrane damage and oxidative stress. In addition, prolonged exposure to AMP-associated toxic chemicals might lead to significant health effects. Most toxicological assessments of AMPs in vitro and in vivo have demonstrated that oxidative stress and inflammation are major mechanisms of action for their toxic effects. Elevated reactive oxygen species production could lead to mitochondrial dysfunction, inflammatory responses, and subsequent apoptosis in experimental models. To date, there has been some evidence suggesting exposure in humans. However, the data are still insufficient, and adverse human health effects need to be investigated. Future research on the existence, exposure, and health effects of AMPs is required for developing preventive and mitigation measures to protect human health.

Matrix complete dissolution concatenated biochar magnetic solid-phase extraction of benzotriazole ultraviolet stabilizers in polyester fibers prior to UPLC-MS/MS analysis

Matrix complete dissolution combined with magnetic solid-phase extraction (MSPE) was applied to extract four benzotriazole ultraviolet stabilizers (BUVSs) from polyester curtains. Ultra-performance liquid chromatography tandem mass spectrometry was coupled to perform the content of trace BUVSs. The procedure was being developed in two steps. The polymer matrix was initially thoroughly dissolved by 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) followed by the addition of precipitant to separate the target from the dissolved polymer matrix. Next, triiron tetraoxide/biochar magnetic material was prepared and utilized as the sorbent for purification of the extract. Ultrasonic extraction coupled with the MSPE method and the proposed method was compared. Better extraction recovery of four BUVSs was acquired by the novel developed extraction method. The purification effect of the new extraction method was established by comparing the matrix effect of the polymer complete dissolution method and the polymer complete dissolution combined with the MSPE method. The extraction parameters were investigated. Under the optimized conditions, correlation coefficient (r) ranging from 0.9969 to 0.9997, limit of detection of 0.2 to 0.8 ng·g-1, and the recovery varied from 81.5 to 102.7% with RSD smaller than 10.7% were obtained for four BUVSs, respectively. This study provides a potential strategy for the efficient extraction and sensitive determination of BUVSs in polyester fibers samples.

Benzotriazole UV stabilizers (BUVs) as an emerging contaminant of concern: a review

Benzotriazole UV stabilizers (BUVs) are a group of industrial chemicals used in various consumer products and industrial applications. Due to its large-scale production and use, BUVs have been detected in all environmental matrices. Humans are exposed to BUVs from environmental media, food, personal care products (PCPs), and consumer products. As a result, BUVs are detected in human breast milk, attracting researchers and regulatory bodies worldwide. BUVs such as UV-328 exhibit the characteristics of persistent organic pollutants (POPs); hence, it has been recently listed under Stockholm Convention POP list. The current review focuses on the occurrence of BUVs in the environment with emphasis on persistency, bioaccumulation, and toxicity (PBT). Scarcity of scientific data on BUVs' properties, environmental occurrence, exposure levels, and effects on organisms poses significant challenges to the policymakers and regulatory bodies in adopting management strategies. The need for a science-based integrated framework for risk assessment and management of BUVs is recommended. Considering the potential threat of BUVs to human health and the environment, it is recommended that BUVs should be taken as a subject of priority research. Studies on the degradation and transformation route of BUVs need to be explored for the sound management of BUVs.

Hydrophobic organic contaminants affiliated with polymer-specific microplastics in urban river tributaries and estuaries

Exposure to microplastics (MPs) and hydrophobic organic contaminants (HOCs) combined at high concentrations may induce adverse effects to aquatic organisms in laboratory-scale studies. To determine environmentally relevant concentrations of HOCs in MPs, it is essential to understand the occurrence of MP-affiliated HOCs in the aquatic environment. Here we report the occurrences of HOCs affiliated with polymer-specific floating MPs from 12 tributaries and three estuaries in the Pearl River Delta, South China. Target HOCs include nine synthetic musks (SMs), 14 ultraviolet adsorbents (UVAs), 15 polycyclic aromatic hydrocarbons (PAHs), eight polybrominated diphenyl ethers (PBDEs), and 14 polychlorinated biphenyls (PCBs). Average concentrations of MP-affiliated ∑9SM, ∑14UVA, ∑15PAH, ∑8PBDE, and ∑14PCB were 1790, 5550, 1090, 412, and 107 ng g-1, respectively. The average concentrations of HOCs affiliated with MPs of different polymer types were 9790, 7220, 72,500, and 55,800 ng g-1 for polyethylene (PE), polypropylene, polystyrene, and other MPs, respectively. As the concentration of PE was the highest among all MPs at the average concentration of 0.77 mg m-3, the monthly outflow of PE-affiliated HOCs accounted for the largest proportion (46 %) in the outflow of MP-affiliated HOCs (2.8 g) to the coastal ocean via three estuaries. These results suggest that HOCs were highly concentrated in MPs and varied among different chemicals and polymer types. Due to the differences of polymer characteristics and half-life of affiliated chemicals, future toxicology studies concerning exposure to these combined pollutants may need to specify polymer types and their affiliated chemicals.

Overcoming the fluorescent interference during Raman spectroscopy detection of microplastics

Owing to environmental concerns, microplastics pollution has been the object of increasing attention. Currently, the chemical composition of microplastics is commonly detected using Raman spectroscopy. Nevertheless, the Raman spectra of microplastics may be overlaid by signals derived from additives (e.g., pigment), resulting in serious interference. In this study, an efficient method is proposed to overcome the interference of fluorescence during Raman spectroscopic detection of microplastics. Four catalysts of Fenton's reagent (Fe2+, Fe3+, Fe3O4, and K2Fe4O7) have been investigated for their capacity to generate hydroxyl radical (•OH), thus potentially eliminating the fluorescent signals in microplastics. The results indicate that the Raman spectrum of microplastics treated with Fenton's reagent can be efficiently optimized in the absence of spectral processing. This method has been successfully applied to the detection of microplastics collected from mangroves, featuring a range of colours and shapes. Consequentially, after 14 h of treatment with sunlight-Fenton (Fe2+: 1 × 10-‍6 M, H2O2: 4 M), the Raman spectra matching-degree (RSMD) of all microplastics were >70.00 %. The innovative strategy discussed in this manuscript can greatly promote the application of Raman spectroscopy in the detection of real environmental microplastics, overcoming interfering signals derived from additives.

Impact of accelerated weathering on the leaching kinetics of stabiliser additives from microplastics

The release of additives from microplastics is known to harm organisms. In the environment, microplastics are exposed to weathering processes which are suspected to influence additive leaching kinetics, the extent and mechanism of which remain poorly understood. We examined the impact of weathering on stabiliser additive leaching kinetics using environmentally relevant accelerated weathering and leaching procedures. Nine binary polymer-additive formulations were specifically prepared, weathered, analysed, and evaluated for their leaching characteristics. Cumulative additive release (Ce) varied widely between formulations, ranging from 0.009 to 1162 µg/g. Values of Ce generally increased by polymer type in the order polyethylene terephthalate < polyamide 6 < polyethylene. The change in leaching kinetics after accelerated weathering was incongruous across the nine formulations, with a significant change in Ce only observed for three out of nine formulations. Physicochemical characterisation of the microplastics demonstrated that additive blooming was the primary mechanism influencing the leaching response to weathering. These findings highlight the dependency of additive fate on the polymer type, additive chemistry, and the extent of weathering exposure. This has significant implications for risk assessment and mitigation, where the general assumption that polymer weathering increases additive leaching may be too simplistic.

Distribution properties of ultraviolet absorbents in different species of biodegradable plastics

Ultraviolet absorbents (UVAs) in the environment have been of increasing concern because of their potential toxicity. However, data on UVAs in the biodegradable plastics are still limited. In this work, we determined the concentrations of 13 UVAs in 6 different types of biodegradable plastic products from Beijing, China, by an ultra-high-performance liquid chromatography with mass spectrometry and found the total concentrations in the range of 37.21-1,138,526 ng g-1. These target UVAs, BP (benzophenone), BP-3, BP-12, UV-328, UV-234, UV-326, UV-329, UV-360 and UV-P are prevalent in the plastic bags, garbage bags, food packaging bags, plastic lunch boxes and tableware, product packing bags and mulch films, except for BP-1, UV-320, UV-327 and UV-PS. This finding showed that the total concentrations of the 13 UVAs in biodegradable mulch films (mean: 1,138,527 ng g-1) were several orders of magnitude higher than those in the other 5 categories of samples (mean: 37.21-186.9 ng g-1). And the UV-328 and BP-1 were the most important components of UVAs in the biodegradable mulch films, with the levels ranging of 726,568-1,062,687 ng g-1 and 317,470-506,178 ng g-1, respectively. As the majority of UVAs were detected in biodegradable plastics, the potential risk of UVAs exposure may exist in the environment with the large-scale use of biodegradable plastics.

Occurrence, spatio-temporal variation and ecological risk assessment of benzotriazole ultraviolet stabilizers (BUVs) in water and sediment of rivers in central India

Occurrence of benzotriazole ultraviolet stabilizers (BUVs) in different environmental matrices has attracted researchers and regulatory agencies worldwide due to its persistency, bioaccumulative and toxic properties. Environmental occurrence of BUVs in Indian freshwater is lacking. The present study analyzed six targeted BUVs in surface water and sediments of three rivers of Central India. BUVs were determined in pre- and post-monsoon seasons to reveal their concentration, spatio-temporal distribution and probable ecological risks. Results indicated that total concentration of BUVs (ƩBUVs) ranged from ND to 42.88 μg/L in water, and ND to 165.26 ng/g in sediments with UV-329 as the predominant BUV in surface water and sediments during pre- and post-monsoon seasons. Surface water samples from Pili River, and sediment of Nag River accounted for maximum BUVs concentration. Partitioning coefficient results confirmed the effective transfer of BUVs from overlaying water to sediments. The observed concentration of BUVs in water and sediments posed low ecological risk to planktons. Untreated municipal discharges and poor waste management practices including dumping of wastes might be the sources of BUVs in water bodies.

Synthesis of a magnetic covalent organic framework for extraction and separation of ultraviolet filters in beverage samples

In this study, a novel magnetic covalent organic framework (Fe₃O₄@TAPB-BTT) was successfully synthesized under mild conditions. The prepared magnetic COF exhibited large surface area (876.3 m² g^-1), porous feature as well as sizeable π-conjugated network structure. Due to the above advantages, Fe₃O₄@TAPB-BTT showed good adsorptive performance for ultraviolet (UV) filters with adsorption capacities ranging from 80.8 to 120.1 mg g^-1. Then the adsorbent was applied to magnetic solid phase extraction (MSPE) of UV filters in beverage samples, followed by UHPLC-MS/MS analysis. The established method showed good accuracy, precision, and reproducibility with satisfactory recoveries (76.9-95.6 %), low limits of detection (0.001-0.15 µg/L), and low relative standard deviations (<9.8 %). Besides, the adsorbent can be reutilized at least ten times, demonstrating satisfactory reusability. This work provided an effective method for the analysis and determination of UV filters in drinks.

Solving a microplastic dilemma? Evaluating additive release with a dynamic leaching method for microplastic assessment (DyLeMMA)

Microplastics and plastic additives are contaminants of emerging environmental concern. Static leaching methods are commonly applied to assess the rate and extent of additive release from microplastics. However, this approach may not be representative of environmental conditions where near infinite dilution or percolation commonly occur. We evaluated three different approaches for assessing additive leaching under environmentally relevant sink conditions, culminating in the refinement and validation of DyLeMMA (Dynamic Leaching Method for Microplastic Assessment). Analysis was performed using a high-resolution liquid chromatography-mass spectrometry method enabling targeted quantification of additives and screening for non-intentionally added substances. Using four different plastics, sink conditions were maintained over the duration of the test, thereby avoiding solubility limited release and ensuring environmental relevance. Background contamination from ubiquitous additive chemicals was minimised, thereby providing good sensitivity and specificity. Resulting data, in the form of additive release curves, should prove suitable for fitting to release models and derivation of parameters describing additive leaching from microplastics.Key attributes of DyLeMMA:•Environmentally relevant dynamic leaching method for microplastics, demonstrated to maintain sink conditions over the test duration,•Simple, fast, and cost-effective approach without complication of using a solid phase sink,•Provide data suitable for understanding microplastic leaching kinetics and mechanisms.

Plastic packaging-associated chemicals and their hazards - An overview of reviews

Plastic packaging contains residues from substances used during manufacturing, such as solvents, as well as non-intentionally added substances (NIAS), such as impurities, oligomers, or degradation products. By searching peer-reviewed literature, we found that at least 10,259 chemicals were related to plastic packaging materials, which include chemicals used during manufacturing and/or present in final packaging items. We then summarized and discussed their chemical structures, analytical instruments, migration characteristics, and hazard categories where possible. For plastic packaging chemicals, examination of the literature reveals gas and liquid chromatography hyphenated to a variety of accurate mass analyzers based on the use of high-resolution mass spectrometry is usually used for the identification of unknown migrants coming from plastic packaging. Chemical migration from food packaging is affected by several parameters, including the nature and complexity of the food, contact time, temperature of the system, type of packaging contact layer, and properties of the migrants. A review of the literature reveals that information on adverse effects is only available for approximately 1600 substances. Among them, it appears that additives are more toxic than monomers to wildlife and humans. Neurotoxicity accounted for the highest proportion of toxicity of all types of chemicals, while benzenoids, organic acids, and derivatives were the most toxic types of chemicals. Furthermore, studies have demonstrated that hydrocarbon derivatives, organic nitrogen compounds, and organometallic compounds have the highest proportions of dermatotoxicity, and organohalogen compounds have the highest proportions of hepatotoxicity. The main contributors to skin sensitization are organic salts. This study provides a basis for comprehensively publicizing information on chemicals in plastics, and could be helpful to better understand their potential risks to the environment and humans.

Prevalence of Novel and Traditional Synthetic Phenolic Antioxidants in Baby Food from China: A Dominant Pathway for Infant Exposure

Synthetic phenolic antioxidants (SPAs) are a group of ubiquitous contaminants with multiple toxicities. However, current knowledge on the occurrence of SPAs in baby food and associated infant exposure is lacking. Herein, we analyzed three categories of baby food from China: infant formula, cereal, and puree, for a broad suite of 11 traditional and 19 novel SPAs. In addition to 11 traditional SPAs, up to 13 novel SPAs were detected in the baby food samples. The median concentrations of novel SPAs for infant formula, cereal, and puree were 604, 218, and 24.1 ng/g, respectively, surpassing those of traditional SPAs (53.4, 62.1, and 10.0 ng/g). The prevalent SPAs in the samples were butylated hydroxytoluene, 2,4-di-tert-butylphenol, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (AO 1010), and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (AO 1076). Source analysis indicated that the prevalence of these four SPAs in baby food was associated with contamination of packaging materials, mechanical processing, or raw ingredients. Migration experiments demonstrated that contamination of plastic packaging constituted an important source. Exposure assessment suggested that there may be no appreciable health risk posed by the SPAs in baby food. Even so, baby food consumption was still a dominant pathway for infant exposure to SPAs, with a higher contribution than breast milk consumption, dust ingestion, dermal dust absorption, and air inhalation, which requires special attention.

Spatiotemporal trends of ultraviolet absorbents in oysters from the Pearl River Estuary, south China during 2015-2020

Ultraviolet absorbents (UVAs) are widely used in various industrial materials, pharmaceuticals, and personal care products, resulting in their frequent occurrences in sediment, water, and biota. However, our understanding of the spatiotemporal characteristics and long-term contamination status of UVAs is still limited. Here, a 6-year biomonitoring study with oysters during wet and dry seasons was conducted to examine the annual, seasonal, and spatial characteristics of UVAs in the Pearl River Estuary (PRE), China. The concentrations of Σ₆UVA ranged from 9.1 to 119 (geometric mean ± standard deviation: 31 ± 22) ng/g dry wt. and peaked in 2018. Significant spatiotemporal variations in UVA contamination were observed. The concentrations of UVAs in oysters during the wet season were higher than the dry season, and concentrations in the more industrialized eastern coast were higher than the western coast (p < 0.05). Environmental factors, including precipitation, temperature, and salinity in water significantly impacted the UVA bioaccumulation in the oysters. The present study highlights that long-term biomonitoring with oysters provided valuable insight in the magnitude and seasonal variation of UVAs in this highly dynamic estuary.

Occurrence, bioaccumulation and ecological risk of organic ultraviolet absorbers in multiple coastal and offshore coral communities of the South China Sea

The occurrence of organic ultraviolet absorbers (OUVAs) in coral reef regions has aroused widespread concern. This study focused on the occurrence, distribution, bioaccumulation and ecological risk of ten OUVAs in both coastal and offshore coral reef regions in the South China Sea. While the Σ₁₀OUVAs was 85 % lower in the offshore seawater (15.1 ng/L) than in the coastal seawater (102.1 ng/L), the Σ₁₀OUVAs was 21 % lower in the offshore corals (1.82 μg/g dry weight (dw)) than in the coastal corals (2.31 μg/g dw). This difference was speculated to relate to the high intensity of human activities in the coastal regions. Moreover, the offshore corals showed higher bioaccumulative capability toward OUVAs (log bioaccumulation factors (BAFs): 1.22-5.07) than the coastal corals (log BAFs: 0.17-4.38), which was presumably the influence of varied physiological status under different environmental conditions. The results of the ecological risk assessment showed that BP-3 resulted in 73 % of coastal corals and 20 % of offshore corals at a risk of bleaching. Therefore, the usage and discharge of BP-3 should be managed and controlled by the countries adjacent to the South China Sea for the protection of coral reefs.

Development and Validation of a DLLME-GC-MS-MS Method for the Determination of Benzotriazole UV Stabilizer UV-327 and Its Metabolites in Human Blood

2-(5-Chloro-benzotriazol-2-yl)-4,6-di-(tert-butyl)phenol (UV-327) is used as an ultraviolet (UV) absorber in plastic materials and coatings. To investigate its metabolism and to assess human exposure, analytical methods are necessary for the determination of UV-327 and its metabolites in human biological specimens. The method thus presented targets the determination of UV-327 and several of its predicted metabolites in blood using protein precipitation, dispersive liquid-liquid microextraction (DLLME) and derivatization. The trimethylsilylated analytes and internal standards are separated by gas chromatography and analyzed with tandem mass spectrometry. The DLLME procedure was optimized with respect to the type and volume of disperser and extraction solvents, the pH value of the sample solution and the addition of salt. During method development, an effective ex vivo lactone/hydroxyl carboxylic acid interconversion was observed for two metabolites, each containing a carboxyl group adjacent to the phenolic hydroxyl group. The analytes resulting from interconversion enabled a more sensitive and reliable determination of the metabolites compared to their native structures. Method validation revealed limits of detection between 0.02 and 0.36 µg/L. The mean relative recovery rates ranged from 91% to 118%. Precision and repeatability were demonstrated by relative standard deviations in the range of 0.6-14.2% and 1.1-13.7%, respectively. The presently described procedure enables the sensitive and robust analysis of UV-327 and its metabolites in human blood and allows the elucidation of the human UV-327 metabolism as well as the assessment of exposure in potentially exposed individuals.

Organic Pollutants Associated with Plastic Debris in Marine Environment: A Systematic Review of Analytical Methods, Occurrence, and Characteristics

Plastic pollution has become one of the most serious environmental problems, and microplastics (MPs, particles < 5 mm size) may behave as a vehicle of organic pollutants, causing detrimental effects to the environment. Studies on MP-sorbed organic pollutants lack methodological standardization, resulting in a low comparability and replicability. In this work, we reviewed 40 field studies of MP-sorbed organic contaminants using PRISMA guidelines for acquiring information on sampling and analytical protocols. The papers were also scored for their reliability on the basis of 7 criteria, from 0 (minimum) to 21 (maximum). Our results showed a great heterogeneity of the methods used for the sample collection, MPs extraction, and instruments for chemicals' identification. Measures for cross-contamination control during MPs analysis were strictly applied only in 13% of the studies, indicating a need for quality control in MPs-related research. The most frequently detected MP-sorbed chemicals were polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and organochlorine pesticides (OCPs). Most of the studies showed a good reliability (>75% of the total score), with 32 papers scoring 16 or higher. On the basis of the collected information, a standardizable protocol for the detection of MPs and MP-sorbed chemicals has been suggested for improving the reliability of MPs monitoring studies.

Plastic debris as a mobile source of additive chemicals in marine environments: In-situ evidence

Plastic debris can act as a source of hazardous chemicals in the ocean, but the significance of its role in the environment is not yet known. To address this question, a comprehensive field study of highly contaminated and non-contaminated islands was conducted. Comparison of the plastic additive hexabromocyclododecanes and ubiquitous contaminants polychlorinated biphenyls in marine invertebrates showed that the load of stranded plastics plays a significant role in the bioaccumulation of plastic additives in the marine debris-contaminated island. Fugacity analysis indicates that net flow of hexabromocyclododecanes occurred from plastics to environmental reservoirs. Additionally, significantly higher levels of antioxidants, 2,4-di-tert-butylphenol and butylated hydroxytoluene, was found in the marine invertebrates inhabiting the marine debris-contaminated island than those inhabiting the marine debris-noncontaminated island, but ultraviolet stabilizers did not show the regional difference. This study provides the first field evidence that the movement of plastic debris in the ocean drives the dispersal of plastic additives to pristine waters.

Benzotriazole ultraviolet stabilizer UV-234 promotes foam cell formation in RAW264.7 macrophages

Benzotriazole ultraviolet stabilizers (BUVSs) have been reported to induce inflammatory responses which may promote cholesterol accumulation and to downregulate the expression of genes involved in cholesterol biosynthesis; hence, we speculated whether BUVSs promote foam cell formation, which plays a key role in all stages of atherosclerosis. Herein, we used high-content imaging to screen all available BUVSs; of all the 17 candidates, 6 of them could promote foam cell formation at 10 μM. Further analyses showed that one BUVS UV-234 markedly increased the foam cell staining intensity by 15.0%-55.9% in the 0.5-10 μM exposure groups in a dose-dependent manner. Cholesterol influx was markedly enhanced by 21.0%-24.5% in the 5-10 μM exposure groups and cholesterol efflux was downregulated by 21.2%-59.3% in the 0.5-10 μM exposure groups, indicating that cholesterol efflux may play a major role in foam formation considering cholesterol efflux was downregulated at a relatively low concentration. Gene expression of ABCA1 and ABCG1 which regulate the cholesterol efflux were also decreased at 0.5-10 μM. The degradation of hypoxia-inducible factor 1α (HIF1α) via the ubiquitin-proteasome system was observed at 0.5-10 μM, probably contributing to the downregulated expression of the genes encoding liver X receptors (LXR) α/β and their targets, ABCA1 and ABCG1. Thus, our study revealed that BUVSs frequently detected in the environment can promote foam cell formation in macrophages, contributing to the risk of atherosclerosis in humans.

Human metabolism and excretion kinetics of benzotriazole UV stabilizer UV-327 after single oral administration

UV-327 (2-(5-chloro-benzotriazol-2-yl)-4,6-di-(tert-butyl)phenol) is used as an ultraviolet (UV) absorber in plastic products and coatings. Due to its ubiquitous distribution in the environment, human exposure is conceivable. In the study presented herein, initial information on the human in vivo metabolism of UV-327 was obtained by single oral administration to three volunteers. Urine and blood samples were collected up to 72 h after exposure. One study participant additionally donated plasma samples. Maximum blood and plasma levels of UV-327 and its two monohydroxylated metabolites UV-327-6-mOH and UV-327-4-mOH were reached 6 h post-exposure. Almost the entire amount found in blood and plasma samples was identified as UV-327, whereas the two metabolites each accounted for only 0.04% of the total amount, indicating that UV-327 is well-absorbed from the intestine, but only partially metabolized. Plasma to blood ratios of UV-327, UV-327-6-mOH, and UV-327-4-mOH ranged from 1.5 to 1.6. Maximum urinary excretion rates of UV-327, UV-327-6-mOH, UV-327-4-mOH, and UV-327-4 + 6-diOH were reached 9-14 h post-exposure. However, only about 0.03% of the orally administered dose of UV-327 was recovered as UV-327 and its metabolites in urine, indicating that biliary excretion may be the major route of elimination of UV-327 and its hydroxylated metabolites. The present study complements the insight in the complex absorption, distribution, metabolism, and elimination (ADME) processes of benzotriazole UV stabilizers (BUVSs).

Identification and quantification of additive-derived chemicals in beached micro-mesoplastics and macroplastics

Although marine plastic debris are expected to retain various chemical additives, little is known about the additives that are retained. We conducted a screening analysis of additives in 261 macroplastic and micro-mesoplastic debris from two beaches. We detected 52 chemicals-antioxidants, phthalates, ultraviolet stabilizers, hindered amine light stabilizers, and flame retardants-and quantified the concentrations of 15 of them. Comparison of the concentrations of Irgafos 168, an antioxidant stabilizer, among sample categories indicated that leaching had occurred from micro-mesoplastics. Differences in diffusion rates between polymer types may explain faster leaching from polyethylene than polypropylene. The significant amounts of Irgafos 168 retained in even micro-mesoplastics indicated the importance of plastics as a vector of additives. This study provides fundamental data needed to assess the risks to organisms from exposure to plastic additives and to understand the effect of stabilizers on the aging behavior of marine plastics.

Oxidation and fragmentation of plastics in a changing environment; from UV-radiation to biological degradation

Understanding the fate of plastics in the environment is of critical importance for the quantitative assessment of the biological impacts of plastic waste. Specially, there is a need to analyze in more detail the reputed longevity of plastics in the context of plastic degradation through oxidation and fragmentation reactions. Photo-oxidation of plastic debris by solar UV radiation (UVR) makes material prone to subsequent fragmentation. The fragments generated following oxidation and subsequent exposure to mechanical stresses include secondary micro- or nanoparticles, an emerging class of pollutants. The paper discusses the UV-driven photo-oxidation process, identifying relevant knowledge gaps and uncertainties. Serious gaps in knowledge exist concerning the wavelength sensitivity and the dose-response of the photo-fragmentation process. Given the heterogeneity of natural UV irradiance varying from no exposure in sediments to full UV exposure of floating, beach litter or air-borne plastics, it is argued that the rates of UV-driven degradation/fragmentation will also vary dramatically between different locations and environmental niches. Biological phenomena such as biofouling will further modulate the exposure of plastics to UV radiation, while potentially also contributing to degradation and/or fragmentation of plastics independent of solar UVR. Reductions in solar UVR in many regions, consequent to the implementation of the Montreal Protocol and its Amendments for protecting stratospheric ozone, will have consequences for global UV-driven plastic degradation in a heterogeneous manner across different geographic and environmental zones. The interacting effects of global warming, stratospheric ozone and UV radiation are projected to increase UV irradiance at the surface in localized areas, mainly because of decreased cloud cover. Given the complexity and uncertainty of future environmental conditions, this currently precludes reliable quantitative predictions of plastic persistence on a global scale.

Environmental concentrations of 2, 4-DTBP cause immunotoxicity in zebrafish (Danio rerio) and may elicit ecological risk to wildlife

Synthetic phenolic antioxidant 2,4-di-tert-butylphenol (2,4-DTBP) has gained growing concerns due to relatively high concentrations in aquatic ecosystems. There are, however, significant knowledge gaps regarding its potential toxicity to aquatic organisms. In this study, zebrafish (Danio rerio) larvae were exposed to 0.01, 0.1, or 1 μM 2,4-DTBP for 6 d. Transcriptomic analysis of larvae revealed that biological processes related to anti-inflammatory function of macrophage M2 lineage were inhibited by 0.01 μM 2,4-DTBP. Decreases of transcripts related to the IL1B-MYD88-NF-κB pathway (i.e., il1b, il1rl1, myd88, irak4, irak1, traf6, ikbkg, nfkbia, nfkb) and protein levels of NF-κB in larvae intestine confirmed anti-inflammatory effects of 2,4-DTBP. Subsequently, larvae exposed to 2,4-DTBP were challenged with E. coli and showed higher survival rate, suggesting sustained activation of inflammation via LPS can be attenuated by 2,4-DTBP. Moreover, histological examination revealed that intestine barrier was compromised and there was an imbalance of intestine macrophage homeostasis. Food intake was also reduced following exposure to 0.1 and 1 μM 2,4-DTBP. In addition, a risk assessment revealed that 2,4-DTBP in surface water pose low to high ecological risks to aquatic organisms. Taken together, exposure to environmentally relevant concentrations of 2,4-DTBP could negatively affect immune response in zebrafish and may elicit ecological risk in fish population.

Occurrence and distribution of organic ultraviolet absorbents in soils and plants from a typical industrial area in South China

Organic ultraviolet absorbents (UVAs) have attracted increasing concern due to their ubiquity, bioaccumulation, and potential toxicity. However, available information on their occurrence and transfer in terrestrial environment is still extremely insufficient. In this study, we investigated twelve UVAs in the soils and five terrestrial plant species from a typical industrial area in South China, and found their total concentrations were 5.87-76.1 (median 13.1) and 17.9-269 (median 82.9) ng/g dry weight, respectively. Homosalate was dominant in soils while benzophenone and octrizole were predominant in plants, likely due to their complex sources and bioaccumulation preferences. The bioaccumulation factors (BAFs) were further evaluated based on the ratios of UVA concentrations in plants and soils. The observed BAFs of UVAs were compound and species-specific, and most of them were much >1.0, indicating the chemicals could be transferred from soils to plants. To the best of our knowledge, this is the first report of organic UVAs in field soil-plant systems, providing information that may improve our understanding of the bioaccumulability of these chemicals in terrestrial environment and the associated risks. More studies are needed to investigate the transfer and bioaccumulation of such chemicals in soils and terrestrial biota.

Beach showers as sources of contamination for sunscreen pollution in marine protected areas and areas of intensive beach tourism in Hawaii, USA

In 2019, sands in nearby runoff streams from public beach showers were sampled on three islands in the State of Hawaii and tested for over 18 different petrochemical UV filters. Beach sands that are directly in the plume discharge of beach showers on three of the islands of Hawaii (Maui, Oahu, Hawai'i) were found to be contaminated with a wide array of petrochemical-based UV-filters that are found in sunscreens. Sands from beach showers across all three islands had a mean concentration of 5619 ng/g of oxybenzone with the highest concentration of 34,518 ng/g of oxybenzone at a beach shower in the Waikiki area of Honolulu. Octocrylene was detected at a majority of the beach shower locations, with a mean concentration of 296.3 ng/g across 13 sampling sites with the highest concentration of 1075 ng/g at the beach shower in Waikiki. Avobenzone, octinoxate, 4-methylbenzylidene camphor and benzophenone-2 were detected, as well as breakdown products of oxybenzone, including benzophenone-1, 2,2'-dihydroxy-4-methoxybenzophenone, and 4-hydroxybenzophenone. Dioxybenzone (DHMB) presented the highest concentration in water (75.4 ng/mL), whereas octocrylene was detected in all water samples. Some of these same target analytes were detected in water samples on coral reefs that are adjacent to the beach showers. Risk assessments for both sand and water samples at a majority of the sampling sites had a Risk Quotient > 1, indicating that these chemicals could pose a serious threat to beach zones and coral reef habitats. There are almost a dozen mitigation options that could be employed to quickly reduce contaminant loads associated with discharges from these beach showers, like those currently being employed (post-study sampling and analysis) in the State of Hawaii, including banning the use of sunscreens using petrochemical-based UV filters or educating tourists before they arrive on the beach.

Long-term exposure of the Mediterranean mussels, Mytilus galloprovincialis to polyethylene terephthalate microfibers: Implication for reproductive and neurotoxic effects

As one of major types of microplastics (MPs), microfibers (MFs) are widely found in the marine ecosystem and can induce diverse impacts on various marine organisms. Sedentary species, such as mussels, can act as bioindicators for monitoring marine contamination. Hence, in this study, we used mussels (Mytilus galloprovincialis) to examine the toxicity of polyethylene terephthalate (PET) MFs of 100 μm size at concentrations of 0.0005, 0.1, 1, 10, and 100 mg/L for 32 days. PET MFs accumulated only in the stomachs and intestines of the mussels and caused digestive tubule atrophy. After exposure to PET MFs, no alteration in the mortality rate, shell height, length, and weight of the mussels was observed. However, the gonadal index decreased with increasing concentrations of PET MFs. This is because PET MFs decrease the sex hormones estradiol and testosterone in mussels, even at environmentally relevant concentrations. Furthermore, chronic exposure to PET MFs increased the activities of antioxidant-related (catalase and superoxide dismutase) and neurotoxicity-related (acetylcholine esterase) enzymes in the digestive gland and gill tissues of mussels. In addition, cellular immune parameters of apoptosis and DNA damage were observed in mussel hemocytes. Thus, this study demonstrates the risks of MPs in real marine environments by assessing how long-term exposure to low concentrations of PET MFs can cause potential sublethal impacts and reproductive failure in mussels.

Effects of benzotriazole UV stabilizers, UV-PS and UV-P, on the differentiation of splenic regulatory T cells via aryl hydrocarbon receptor

Benzotriazole UV stabilizers (BUVSs) are widely used as additives in various materials, including plastics, to prevent damage from UV-irradiation. However, despite the extensive usage of BUVSs, information on their toxicological properties is limited. In this study, we investigated the effect of BUVSs on the immune regulatory system via the aryl hydrocarbon receptor (AhR). A cell-based transactivation assay using DR-EcoScreen cells revealed that, among 13 BUVSs tested, UV-P, UV-PS, UV-9, and UV-090 activated AhR in a dose-dependent manner. In particular, the AhR agonistic activity of UV-PS was about 10-fold more potent than those of UV-P, UV-090, and UV-9, and UV-PS acted as a full agonist against AhR. In order to investigate the immune regulatory effects of these BUVSs, we orally treated C57BL/6 mice with UV-PS or UV-P (10, 30, and 100 mg/kg) and studied the differentiation of regulatory T cells (Tregs) in spleen cells. Flow-cytometry analysis revealed that the administration of UV-PS (30 and 100 mg/kg) or UV-P (100 mg/kg) significantly increased the population of CD4⁺-/CD25⁺-/Foxp3⁺ Tregs in the spleen. In addition, we found that the in vitro exposure of mouse splenocytes to UV-PS (10 and 30 μM) or UV-P (30 μM) as well as to TCDD (0.1 nM) significantly induced Tregs. Notably, the induction of Tregs was eliminated by co-treatment with an AhR antagonist, CH-223191, in each case. Taken together, these findings suggest that some BUVSs might induce Tregs through direct AhR activation and act as immunosuppressive modulators.

Equilibrium leaching of selected ultraviolet stabilizers from plastic products

Despite the importance of (micro)plastics in the release of plastic additives, the leaching mechanism of organic plastic additives from various plastic materials is poorly understood. In this study, the equilibrium leaching of five highly hydrophobic ultraviolet (UV) stabilizers (UV326, UV327, UV328, UV329, and UV531) from three plastics (low-density polyethylene (LDPE), polyethylene terephthalate (PET), and polystyrene (PS)), was investigated employing acetonitrile-water cosolvent systems. Their extrapolated water solubilities were in the 0.15-0.54 μg L^-1 range, limiting their transport as "dissolved" in water and (micro)plastics are likely those particulate carriers. The equilibrium leaching of UV stabilizers from plastics was better explained by the Flory-Huggins model incorporating the nonideal behavior caused by the size disparity between UV stabilizers and polymer materials and their compatibility. Specifically, leaching of UV stabilizers from LDPE showed a positive deviation from Raoult's law, whereas slight negative deviations were observed in PET and PS. In addition, the equilibrium concentration of the benzotriazoles in LDPE increased linearly with the volume fraction up to only 0.4%. These observations could be explained by the unfavorable interactions of UV stabilizers with polyethylene, indicating that polymer type should be also important when evaluating the fate of hydrophobic additives. Because equilibrium distribution of additives between (micro)plastics and water is crucial for evaluating the fate and transport of hydrophobic plastic additives, further studies on the leaching equilibrium of various additives from different plastic materials are necessary.

Residual additives in marine microplastics and their risk assessment - A critical review

This review summarizes the current state of knowledge regarding the risk assessment of plastic-associated residual additives, i.e. residual monomers, degradation products and additives, in the marine environment, also considering effects of weathering and bioavailability. Experimental studies have found a number of organic and metal additive compounds in leachates from plastics, and the analysis of weathered plastic particles, such as polyethylene, polypropylene and polystyrene particles sampled on beaches and shorelines, has identified residual additives, such as flame retardants, plasticizers, UV stabilizers and antioxidants. While the transfer of e.g. PBDEs to organisms upon ingestion has been demonstrated, studies on uptake and bioaccumulation of plastic-associated chemicals are inconclusive. Studies on hazard and risk assessments are few, and focus on monomers and/or a limited number of high concentration additives, such as phthalates and flame retardants. The risk assessment results vary between low, moderate and high risks of specific additives, and are not necessarily consistent for the same compound. Given the large number of chemicals potentially introduced into the marine environment with plastic particles and the challenges associated with the correct quantification of exposure concentrations and toxicity thresholds, the question arises whether new risk assessment concepts may be needed.