Occurrence of substituted diphenylamine antioxidants and benzotriazole UV stabilizers in Arctic seabirds and seals

Discovery of novel benzotriazole ultraviolet stabilizers in surface water

The comprehensive understanding of the occurrence of benzotriazole UV stabilizers (BZT-UVs) in environmental surface water is imperative due to their widespread application and potential aquatic toxicity. We conducted an analysis of 13 traditional BZT-UVs in surface water samples collected from Taihu Lake (TL, n = 23) and Qiantang River (QR, n = 22) in China. The results revealed that 5‑chloro-2-(3,5-di-tertbutyl-2-hydroxyphenyl)-benzotriazole (UV-327) was consistently the predominant BZT-UV in water samples from TL (mean 16 ng/L; detection frequency 96 %) and QR (14 ng/L; 91 %). Furthermore, we developed a characteristic fragment ion-based strategy to screen and identify unknown BZT-UVs in collected surface water, utilizing a high-resolution mass spectrometer. A total of seven novel BZT-UVs were discovered in water samples, and their chemical structures were proposed. Four of these novel BZT-UVs were further confirmed with standards provided by industrial manufacturers. Semi-quantitative analysis revealed that among discovered novel BZT-UVs, 2-(2‑hydroxy-3‑tert‑butyl‑5-methylphenyl)-benzotriazole was consistently the predominant novel BZT-UV in TL (mean 4.1 ng/L, detection frequency 70 %) and QR (2.8 ng/L, 77 %) water. In TL water, the second predominant novel BZT-UV was 2-(3-allyl-2‑hydroxy-5-methylphenyl)-2H-benzotriazole (mean 3.9 ng/L, Collapse

Key Words

• Benzotriazole UV stabilizers
• Non-target analysis
• Novel BZT-UVs
• Surface water
• UV-327

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MESH Headings

• Triazoles/chemistry
• Water Pollutants, Chemical/chemistry
• China
• Lakes/chemistry
• Ultraviolet Rays
• Rivers/chemistry
• Environmental Monitoring

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Grants Collapse

Affiliation(s)

Yuanchen Chen Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China
Ruyue Guo Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China
Kaizhen Liao Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China
Wenfei Yu Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China
Pengfei Wu Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu 210037, PR China
Hangbiao Jin Key Laboratory of Microbial Technology for Industrial Pollution Control of Zhejiang Province, College of Environment, Zhejiang University of Technology, Hangzhou, Zhejiang 310032, PR China.

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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.

Aniline antioxidants in road dust, parking lot dust, and green-belt soil in Harbin, a megacity in China: Occurrence, profile, and seasonal variation

Aniline antioxidants (ANs) are widely used as industrial chemicals in products composed of rubber. ANs originate mainly from vehicles, where tire wear particles end up in dust and soil after being deposited on roads. Nowadays, limited information is available on the fate and seasonal variation of ANs in the road environment. In this study, we investigated the occurrence of 32 ANs in dust and soil from different road environments, including road dust, garage dust, parking lot dust, and green-belt soil. The total concentrations of ANs were 369 ng g-1 in road dust, 712 ng g-1 in garage dust, and 687 ng g-1 in parking lot dust. These concentrations are several times higher than that in green-belt soil (128 ng g-1). The highest concentrations of N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine (6PPD) were found in dust and soil. Furthermore, notable seasonal differences were observed, with significantly higher concentrations of ANs in autumn than those in spring. In the main urban area, roads with high traffic volume exhibited higher concentrations of ANs than those with low traffic volume, indicating that ANs were produced by vehicle-related sources.

Tissue-specific distributions of organic ultraviolet absorbents in free-range chickens and domestic pigeons from Guangzhou, China

The ecological risks of organic ultraviolet absorbents (UVAs) have been of increasing concern. Studies have found that these chemicals could be accumulated in terrestrial animals and pose toxicities. However, tissue distribution of UVAs in terrestrial species was far from well understood. In this study, free-range chickens and domestic pigeons were selected to investigate the occurrence and tissue distribution of UVAs. Total concentrations of eleven UVAs in muscles ranged from 778 to 2874 (mean 1413 ± 666) ng/g lipid weight, which were higher than those in aquatic species worldwide. Since low UVA concentrations in local environment were previously reported, the results implied the strong accumulation of UVAs in studied species. Brain, stomach and kidney were main target organs for studied UVAs, differentiating from the strong liver sequestration in aquatic species. The mean tissue-to-muscle ratios of 1.02-4.23 further indicated the preferential accumulation of target UVAs in these tissues. The tissue-to-blood ratios of benzophenone (BP), 2-ethylhexyl salicylate (EHS) and homosalate (HMS) in brain were 370, 1207 and 52.0, respectively, implying their preferential accumulation in brain. More research is needed to characterize the toxicokinetics and tissue distribution of UVAs in terrestrial wild species, in order to further understand their potential risks.

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.

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.

Spatial distribution, partitioning, and ecological risk assessment of benzotriazoles, benzothiazoles, and benzotriazole UV absorbers in the eastern shelf seas of China

Benzotriazoles (BTRs), benzothiazoles (BTHs), and benzotriazole UV stabilizers (BUVs) have attracted increasing attention due to their ubiquity in the environment, toxicity, and potential ecological risks. However, information on their distributions in the ocean is scarce. In this study, BTRs, BTHs, and BUVs were firstly determined in the surface seawater, sea-surface microlayer (SML), suspended particulate matter (SPM), and sediments of the Yellow Sea (YS) and East China Sea (ECS). The spatial distributions of BTRs, BTHs, and BUVs in the YS and ECS showed offshore decreasing trend in their concentrations, indicating that terrestrial inputs from runoff and rivers had important influences on their distributions. The organic carbon normalized partition coefficients (log Koc) of target contaminants in surface seawater-SPM (3.06-4.16 L/g) and bottom seawater-sediment (2.55-4.82 L/kg) systems were determined. SPM showed greater sorption capacities for most target contaminants than the sediment. The burial capacities of BTHs, BTRs, and BUVs from SPM to surface sediments were evaluated using their respective log Kow values and their sedimentary fluxes in the YS and ECS were quantified. BTRs, BTHs, and BUVs were enriched in the SML, with the enrichment extents of the suspended particulate phase being obviously lower than those of the dissolved phase. The ecological risks of BTRs, BTHs, and BUVs were evaluated using the risk quotient (RQ) method, which showed no toxic risk to aquatic organisms throughout the water phases, but high risk in nearshore sediments.

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.

Occurrence of polybrominated diphenyl ethers and benzotriazole UV stabilizers in the hadal amphipod Hirondellea gigas

The accumulation of polybrominated diphenyl ethers (PBDEs) and benzotriazole UV stabilizers (BZT-UVs) were examined in the hadal amphipod Hirondellea gigas caught from a near-land trench off the Japan island (9200 m). H. gigas were collected from two distinct sites: one is located at the outlet of submarine canyons directly connected to land and the other is apart from the outlet and geographically isolated from the first site. The level of the PBDEs in H. gigas at the canyon outlet (mean 219 ng/g lipid weight (l.w.)) was significantly higher than that in the isolated site (mean 42 ng/g l.w.) and BZT-UVs were only detected within the first site (mean 1.5 ng/g wet weight). In addition to vertical transport from the surface water, near-land trenches associated with submarine canyons and troughs may have more complex influx of contaminants through horizontal transportation from the land, resulting in more severe contamination.

Embryonic Exposure to UV-328 Impairs the Cell Cycle in Zebrafish (Danio rerio) by Inhibiting the p38 MAPK/p53/Gadd45a Signaling Pathway

The benzotriazole UV stabilizer UV-328 is well known for its potent antioxidative properties; however, there are concerns about how it may affect signaling nodes and lead to negative consequences. This study identified the key signaling cascades involved in oxidative stress in zebrafish (Danio rerio) larvae and evaluated the cell cycle arrests and associated developmental alternations. Exposure to UV-328 at 0.25, 0.50, 1.00, 2.00, and 4.00 μg/L downregulated gene expression associated with oxidative stress (cat, gpx, gst, and sod) and apoptosis (caspase-3, caspase-6, caspase-8, and caspase-9) at 3 days postfertilization (dpf). The transcriptome aberration in zebrafish with disrupted p38 mitogen-activated protein kinase (MAPK) cascades was validated based on decreased mRNA expressions of p38 MAPK (0.36-fold), p53 (0.33-fold), and growth arrest and DNA damage-inducible protein 45 α (Gadd45a) (0.52-fold) after a 3- and 14-day exposure alongside a correspondingly decreased protein expression. The percentage of cells in the Gap 1 (G1) phase increased from 69.60% to a maximum of 77.07% (p < 0.05) in the 3 dpf embryos. UV-328 inhibited the p38 MAPK/p53/Gadd45a regulatory circuit but promoted G1 phase cell cycle arrest, abnormally accelerating the embryo hatching and heart rate. This study provided mechanistic insights that enrich the risk profiles of UV-328.

Organic chemicals associated with rubber are more toxic to marine algae and bacteria than those of thermoplastics

The current study investigated the chemical complexity of fifty plastic (36) and elastomer/rubber (14) methanol extracts from consumer products, focusing on the association with toxicity in two screening assays (bacteria luminescence and marine microalgae). The chemical composition varied considerably between the products and polymers. The most complex sample (car tire rubber) contained 2456 chemical features and the least complex (disposable water bottle) only 39 features, with a median of 386 features across all products. Individual extract toxicity also varied significantly across the products and polymers, with the two toxicity assays showing comparable results in terms of defining low and high toxicity extracts, and correlation between medium toxicity extracts. Chemical complexity and abundance both correlated with toxicity in both assays. However, there were strong differences in toxicity between plastic and elastomer extracts. Overall, 86-93 % of the 14 elastomer extracts and only 33-36 % of other polymer extracts (n = 36) were more toxic than the median. A range of compounds were tentatively identified across the sample set, with several concerning compounds being identified, mostly in the elastomers. While the current focus on plastic chemicals is towards thermoplastics, we show that elastomers may be of more concern from an environmental and human health perspective.

No accumulation of microplastics detected in western Canadian ringed seals (Pusa hispida)

Ringed seals (Pusa hispida) play a crucial role in Arctic food webs as important pelagic predators and represent an essential component of Inuvialuit culture and food security. Plastic pollution is recognized as a global threat of concern, and Arctic regions may act as sinks for anthropogenic debris. To date, mixed evidence exists concerning the propensity for Canadian Arctic marine mammals to ingest and retain plastic. Our study builds on existing literature by offering the first assessment of plastic ingestion in ringed seals harvested in the western Canadian Arctic. We detected no evidence of microplastic (particles ≥80 μm) retention in the stomachs of ten ringed seals from the Inuvialuit Settlement Region (ISR) in the Northwest Territories, Canada. These results are consistent with previous studies that have found that some marine mammals do not accumulate microplastics in evaluated regions.

Amino antioxidants: A review of their environmental behavior, human exposure, and aquatic toxicity

Amino antioxidants (AAOs), a suite of emerging organic contaminants, have been widely used in numerous industrial and commercial products to inhibit oxidation and corrosion. Recently, their environmental ubiquity, health risks, bioaccumulative and toxic potential have led to mounting public concern. This review summarizes the current state of knowledge on the production and usage, environmental occurrence, bioavailability, human exposure, and aquatic toxicity of representative AAOs, and provides suggestions for future research directions. Previous studies have revealed widespread distribution of many AAOs in various environmental matrixes, including air, water, sediment, dust, and biota. In addition to parent compounds, their degradation products, such as 2-anilino-5-(1,3-dimethylbutylamino)-1,4-benzoquinone (6PPD-Q) and 4-nitrodiphenylamine (4-NO₂-DPA), have also been detected at high levels in multiple compartments. Dust ingestion and air inhalation are the two most well-investigated routes for human exposure to AAOs and their transformation products, while studies on other pathways (e.g., skin contact and dietary intake) still remain extremely limited. Moreover, AAO burdens in human tissue have been poorly documented. Toxicological data have shown that a few AAOs may cause teratogenic, developmental, reproductive, endocrinic, neuronic, and genetic toxicity to aquatic organisms, and the toxic capacities of degradation products differ from their precursors. Future studies should focus on elucidating AAO exposure for humans and associated health risks. Additionally, more attention should be given to AAO transformation products (particularly those quinoid derivatives possessing substantial affinity with DNA) and to the effects of complex mixtures of these chemicals.

High levels of synthetic antioxidants and ultraviolet filters in children's car seats

Forty-seven compounds among synthetic phenolic and amino antioxidants and ultraviolet filters, three suites of widely used chemical additives, were measured in eighteen popular children's car seats (fabric, foam, and laminated composites of both layers) marketed in the United States in 2018. Significantly higher levels of target compounds were found in foam and composite samples than in fabric samples. Median total concentrations of phenolic antioxidants and their transformation products ranged from 8.11 μg/g in fabric to 213 μg/g in foam In general, isooctyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (AO-1135) and 2,4-di-tert-butylphenol (24-DBP) were the most abundant among all target compounds with maximum levels of526 μg/g in composite and 13.7 μg/g, respectively. The total concentrations of amino antioxidants and their transformation products and of ultraviolet filters were at least one order of magnitude lower than those of phenolic antioxidants, with medians of 0.15-37.1 μg/g and 0.29-1.81 μg/g, respectively, in which the predominant congeners were 4-tert-butyl diphenylamine (BDPA), 4,4'-di-tert-butyl diphenylamine (DBDPA), 4-tert-octyl diphenylamine (ODPA), 2,4-dihydroxybenzophenone (BP-1), 2-hydroxy-4-methoxybenzophenone (BP-3), and 2-(2-benzotriazol-2-yl)-4-methylphenol (UV-P). Large variabilities in usage of these chemicals resulted in different compositional patterns among the car seats. These results suggest that these compounds are major polymeric additives in children's car seats as they are present at greater levels than previously measured groups of chemicals like brominated flame retardants and per- and polyfluoroalkyl substances. Given the documented toxic potentials of synthetic antioxidants and ultraviolet filters, their abundances in children products are a cause for concern.

Assessment of contaminants of emerging concern in European apex predators and their prey by LC-QToF MS wide-scope target analysis

Apex predators are good indicators of environmental pollution since they are relatively long-lived and their high trophic position and spatiotemporal exposure to chemicals provides insights into the persistent, bioaccumulative and toxic (PBT) properties of chemicals. Although monitoring data from apex predators can considerably support chemicals' management, there is a lack of pan-European studies, and longer-term monitoring of chemicals in organisms from higher trophic levels. The present study investigated the occurrence of contaminants of emerging concern (CECs) in 67 freshwater, marine and terrestrial apex predators and in freshwater and marine prey, gathered from four European countries. Generic sample preparation protocols for the extraction of CECs with a broad range of physicochemical properties and the purification of the extracts were used. The analysis was performed utilizing liquid (LC) chromatography coupled to high resolution mass spectrometry (HRMS), while the acquired chromatograms were screened for the presence of more than 2,200 CECs through wide-scope target analysis. In total, 145 CECs were determined in the apex predator and their prey samples belonging in different categories, such as pharmaceuticals, plant protection products, per- and polyfluoroalkyl substances, their metabolites and transformation products. Higher concentration levels were measured in predators compared to prey, suggesting that biomagnification of chemicals through the food chain occurs. The compounds were prioritized for further regulatory risk assessment based on their frequency of detection and their concentration levels. The majority of the prioritized CECs were lipophilic, although the presence of more polar contaminants should not be neglected. This indicates that holistic analytical approaches are required to fully characterize the chemical universe of biota samples. Therefore, the present survey is an attempt to systematically investigate the presence of thousands of chemicals at a European level, aiming to use these data for better chemicals management and contribute to EU Zero Pollution Ambition.

44-Year Retrospective Analysis of Ultraviolet Absorbents and Industrial Antioxidants in Seabird Eggs from the Canadian Arctic (1975 to 2019)

Ultraviolet (UV) absorbents and industrial antioxidants are contaminants of emerging concern (CECs), but little is known about their distribution in Arctic wildlife, as well as how these contaminants vary over time, across regions, and between species. We used archived egg samples to examine the temporal patterns of 26 UV absorbents and industrial antioxidants in three seabird species (black-legged kittiwakes Rissa tridactyla, thick-billed murres Uria lomvia, northern fulmars Fulmarus glacialis) sampled in Arctic Canada between 1975 and 2019. Various synthetic phenolic antioxidants, aromatic secondary amines, benzotriazole UV stabilizers, and organic UV filters were detected in the seabird eggs. Overall, kittiwakes had higher levels of several UV absorbents and industrial antioxidants. Most target contaminants reached their peak concentrations at different points during the 44-year study period or did not vary significantly over time. None of these contaminant concentrations have increased in recent years. The antioxidant 2-6-di-tert-butyl-4-methylphenol (BHT) was the most frequently detected contaminant in seabird eggs, and its level significantly declined over the course of the study period in kittiwake eggs but did not change in the eggs of murres and fulmars. Future research should examine the effects of these CECs on the health of avian species, the sources, and exposure pathways of these contaminants.

Occurrence and temporal trends of industrial antioxidants and UV absorbents in the endangered St. Lawrence Estuary beluga whale (Delphinapterus leucas)

Elevated contaminant exposure has been identified as a stressor that has negative impacts on the health and recovery of the endangered St. Lawrence Estuary (SLE) beluga (Delphinapterus leucas) population. However, the accumulation of many groups of contaminants of emerging concern is still unknown in the SLE beluga. The objective of this study was to investigate the occurrence and temporal trends (2000-2017) of synthetic phenolic antioxidants (SPAs), secondary aromatic amines (Ar-SAs), benzotriazole UV stabilizers (BZT-UVs), and organic UV filters (UVFs) in the blubber (n = 69) and liver (n = 80) of SLE beluga carcasses recovered in the SLE. The SPA 2,6-di-tert-butyl-1,4-benzoquinone (BHTQ) was the most prevalent contaminant in the blubber (detection frequency: 86 %; median: 71.1 ng/g wet weight (ww)) and liver (50 %; 12.2 ng/g ww) of SLE belugas. In the blubber, 2-hydroxy-4-methoxybenzophenone (BP3) (36 %; 3.15 ng/g ww) and 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethyl butyl)phenol (UV329) (49 %; 6.84 ng/g ww) were the most frequently detected UVFs and BZT-UVs, respectively. Ar-SAs were not detected in most of the blubber and liver samples. Blubber accumulated higher levels of BHTQ and UV329 than liver, whereas the levels of BP3 were greater in the liver. Male SLE beluga accumulated greater concentrations of UV329 in blubber compared to females. These results indicated that the accumulation of BHTQ, UV329 and BP3 in SLE belugas is tissue- and sex-specific. BHTQ showed a decreasing trend in the blubber (2000-2017) of male SLE beluga, whereas no significant trend of this contaminant was found in females. UV329 showed no discernible temporal trend. This study established a baseline for the future monitoring of SPAs, Ar-SAs, BZT-UVs and UVFs in belugas and other marine mammals.

Co-contaminants of microplastics in two seabird species from the Canadian Arctic

Through ingestion and subsequent egestion, Arctic seabirds can bioaccumulate microplastics at and around their colony breeding sites. While microplastics in Arctic seabirds have been well documented, it is not yet understood to what extent these particles can act as transport vehicles for plastic-associated contaminants, including legacy persistent organic pollutants (POPs), trace metals, and organic additives. We investigated the occurrence and pattern of organic and inorganic co-contaminants of microplastics in two seabird species from the Canadian Arctic - northern fulmar (Fulmarus glacialis) and black-legged kittiwake (Rissa tridactyla). We found that fulmars had higher levels of plastic contamination and emerging organic compounds (known to be plastic additives) than kittiwakes, whereas higher concentrations of legacy POPs were found in kittiwakes than the fulmars. Furthermore, fulmars, the species with the much larger foraging range (∼200 km), had higher plastic pollution and overall contaminant burdens, indicating that birds may be acting as long-range transport vectors for plastic-associated pollution. Our results suggest a potential connection between plastic additive contamination and plastic pollution burdens in the bird stomachs, highlighting the importance of treating plastic particles and plastic-associated organic additives as co-contaminants rather than separate pollution issues.

Estimating the Bioaccumulation Potential of Hydrophobic Ultraviolet Stabilizers Using Experimental Partitioning Properties

Although hydrophobic ultraviolet (UV) stabilizers are an emerging environmental concern because of their widespread occurrence, persistence, and bioaccumulation potential, experimental values of their partitioning properties required for risk assessment are scarce. In this study, n-octanol-water partition (K_ow) and lipid–water partition constants (K_lipw), which are key parameters for environmental risk assessment, were experimentally determined for five selected hydrophobic UV stabilizers (UV326, UV327, UV328, UV329, and UV531) based on third-phase partitioning among polydimethylsiloxane (PDMS), water, and n-octanol/lipid. The partition constants between PDMS and water (K_PDMSw), obtained using the dynamic permeation method were used to derive K_ow and K_lipw. The obtained log K_ow and log K_lipw values were in the ranges of 7.08–7.94 and 7.50–8.34, respectively, indicating that the UV stabilizers exhibited a high bioaccumulation potential in aquatic environments. The experimental K_ow and K_lipw values obtained in this study provide valuable information for the evaluation of the fate, distribution, bioavailability, and toxicity of the UV stabilizers in aquatic environments.

Benzotriazole Ultraviolet Stabilizers Promote Breast Cancer Cell Proliferation via Activating Estrogen-Related Receptors α and γ at Human-Relevant Levels

Benzotriazole ultraviolet stabilizers (BUVSs) are ubiquitous emerging pollutants that have been reported to show estrogenic disruption effects through interaction with the classic estrogen receptors (ERs) in the fashion of low activity. The present study aims at revealing the potential disruption mechanism via estrogen-related receptors α and γ (ERRα and ERRγ) pathways. By the competitive binding assay, we first found that BUVSs bond to ERRγ ligand binding domain (ERRγ-LBD) with Kd ranging from 0.66 to 19.27 μM. According to the results of reporter gene assays, the transcriptional activities of ERRα and ERRγ were promoted by most tested BUVSs with the lowest observed effective concentrations (LOEC) from 10 to 100 nM, which are in the range of human exposure levels. At 1 μM, most tested BUVSs showed higher agonistic activity toward ERRγ than ERRα. The most effective two BUVSs promoted the MCF-7 proliferation dependent on ERRα and ERRγ with a LOEC of 100 nM. The molecular dynamics simulation showed that most studied BUVSs had lower binding free energy with ERRγ than with ERRα. The structure-activity relationship analysis revealed that molecular polarizability, electron-donating ability, ionization potential, and softness were the main structural factors impacting the binding of BUVSs with ERRγ. Overall, our results provide novel insights into the estrogenic disruption effects of BUVSs.

Occurrence, removal and mass balance of substituted diphenylamine antioxidants in wastewater treatment plants in Northeast China

Substituted diphenylamine antioxidants (SDPAs) are additives used in various commodities and are commonly found in environmental samples. However, limited information was available on their fate and removal in wastewater treatment plants (WWTPs). This paper reports the results on the occurrence and removal efficiency of ten selected SDPAs in six WWTPs equipped with different treatment processes in Northeast China. Quite similar distributions of different SDPA congeners were shown in the studied WWTPs, with ditertoctyl-diphenylamine (C8/C8-DPA), tertbutyl-tertoctyl-diphenylamine (C4/C8-DPA), and tertoctyl-diphenylamine (C8-DPA) being always dominant in the influent, effluent, and sludge (total > 80%). A cyclic activated sludge system combined with a V-shape filter achieved the highest removal efficiencies of SDPAs among various treatment processes. Styrenated-diphenylamine1 (S-DPA1) (96 ± 10%), C8-DPA (95 ± 5.5%), and distyrenated-diphenylamine1 (DS-DPA1) (94 ± 9.3%) showed high and stable removal efficiencies, whereas C4/C8-DPA (85 ± 31%) and C8/C8-DPA (84 ± 62%) showed considerably varied removal efficiencies. Per-day discharges of SDPAs to the receiving environment through effluent and sludge were estimated as 828 ± 350 and 5578 ± 5196 mg, respectively. A median of 85% of the initial mass loadings of SDPAs was found in the sludge samples, suggesting that the observed removal of SDPAs in the WWTPs was caused by their sorption to the sludge, rather than biodegradation/transformation. This work provides an overall description of the occurrence, fate, and mass balance of SDPAs in WWTPs in Northeast China and highlights a new emission route to the environment via WWTPs.

Simultaneous determination of low molecule benzotriazoles and benzotriazole UV stabilizers in wastewater by ultrasound-assisted emulsification microextraction followed by GC-MS detection

A rapid, sensitive, economically and ecologically friendly method based on one-step ultrasound-assisted emulsification microextraction and in situ derivatization followed by gas chromatography-mass spectrometry for simultaneous determination of low molecular benzotriazoles and benzotriazole-based ultraviolet filters was developed. The optimized method allows quantification of benzotriazole, 4-methylbenzotriazole, 5-methylbenzotriazole; 5-chlorobenzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzortriazole and 2-(2'-hydroxy-5'-(1,1,3,3-tetramethylbutyl)phenyl)benzotriazole in municipal and industrial (dairy) wastewater. The method was validated using real influent and effluent wastewater and samples at various stages of the purification process. Relative recoveries obtained using wastewater as sample matrix were between 77 and 137%, method limits of detection from 0.001 to 0.035 µg/L, method limits of quantification from 0.003 to 0.116 µg/L, the repeatability expressed by the coefficient of variation did not exceed 12%. The use of the method for the determination of tested compounds in municipal and industrial wastewater showed their presence in most of the tested samples, in concentrations from LoD to 6.110 µg/L. The conducted studies of samples from municipal wastewater treatment plant located in north-east Poland showed that the effectiveness of benzotriazole removal by this plant wasfrom 29 to 84%. The load of tested compounds released into the environment by this facility ranges from 2 to 269 mg/day/1000 inhabitants.

Diphenylamine Antioxidants in wastewater influent, effluent, biosolids and landfill leachate: Contribution to environmental releases

Diphenylamine antioxidants (DPAs) are widely used industrial chemicals. Wastewater effluents and biosolids are important pathways for DPAs to enter the environment. Information on the fate of DPAs in wastewater treatment plants (WWTPs) and their environmental releases is limited. In this study, we characterized the occurrence, removal efficiencies, distribution, mass balance, and environmental releases of 17 DPAs in ten Canadian WWTPs and four landfill sites from 2013 to 2015. These WWTPs are different in sizes, and treatment technologies. Median concentrations of ΣDPAs were 78 ng/L in influent, 6.9 ng/L in effluent, 326 ng/L in leachate, and 445 ng/g in biosolids (dry weight), respectively. Diphenylamine (DPA) and ditertoctyl-diphenylamine (DTO-DPA) were the predominant congeners of DPAs in all the matrices. Residues of DPAs were not completely removed during wastewater treatment processes: most DPAs were detected in at least one sample of WWTP effluent with the highest concentration of 117 ng/L (DPA). Overall, high removal efficiencies (median > 90%) of most of the DPAs were observed in the secondary and advanced treatment, as well as in the facultative and aerated lagoons. In contrast, primary treatment exhibited a lower removal efficiency of the DPAs. Mass balance analysis shows that sorption to biosolids is the major removal pathway of DPAs in WWTPs. The results also highlight that environmental releases of DPAs via biosolid applications (70 mg/d/1000 people) can be over several times higher than that via wastewater effluent (2.5-36 mg/d/1000 people).

Transcriptional, biochemical and histological alterations in adult zebrafish (Danio rerio) exposed to benzotriazole ultraviolet stabilizer-328

The occurrence of Benzotriazole Ultraviolet Stabilizer-328 (BUV-328) in different environmental and biological matrices is of immediate environmental concern. In the present study, we evaluated the toxicity of BUV-328 in zebrafish liver tissues to understand the role of oxidative damage in hepatotoxicity. Adult zebrafish were exposed to 0.01, 0.1 and 1 mg/L of BUV-328. At the end of 14, 28 and 42 days, liver tissues were examined for the responses of antioxidant enzymes, gene expression and histopathological alterations. The results indicated that superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities were elevated at concentrations of 0.1 and 1 mg/L on 14th and 28th day. Glutathione S-transferase (GST) activity and malondialdehyde (MDA) levels were elevated in all the treated groups. The transcriptional levels of genes encoding sod, cat, gpx and gst enzymes were increased at 14th day and then declined (except sod on 28th day). Moreover, transcription of cyp1a and hsp70 were up-regulated throughout the study period. Histopathological lesions such as hypertrophy, cellular and nuclear enlargement, cytoplasmic and nuclear degeneration, necrosis with pyknotic nuclei, lipid and cytoplasmic vacuolization and nuclear displacement to the periphery were found to be increased with the dose and exposure duration. In brief, our findings indicate that even a low dose of BUV-328 is toxic to induce oxidative stress and liver damage in zebrafish over a long period of exposure.

A Horizon Scan of research priorities to inform policies aimed at reducing the harm of plastic pollution to biota

Plastic pollution in the oceans is a priority environmental issue. The recent increase in research on the topic, coupled with growing public awareness, has catalyzed policymakers around the world to identify and implement solutions that minimize the harm caused by plastic pollution. To aid and coordinate these efforts, we surveyed experts with scientific experience identified through their peer-reviewed publications. We asked experts about the most pressing research questions relating to how biota interact with plastic pollution that in turn can inform policy decisions and research agendas to best contribute to understanding and reducing the harm of plastic pollution to biota. We used a modified Horizon Scan method that first used a subgroup of experts to generate 46 research questions on aquatic biota and plastics, and then conducted an online survey of researchers globally to prioritize questions in terms of their importance to inform policy development. One hundred and fifteen experts from 29 countries ranked research questions in six themes. The questions were ranked by urgency, indicating which research should be addressed immediately, which can be addressed later, and which are of limited relevance to inform action on plastics as an environmental pollutant. We found that questions relating to the following four themes were the most commonly top-ranked research priorities: (i) sources, circulation and distribution of plastics, (ii) type of harm from plastics, (iii) detection of ingested plastics and the associated problems, and (iv) related economies and policy to ingested plastics. While there are many research questions on the topic of impacts of plastic pollution on biota that could be funded and investigated, our results focus collective priorities in terms of research that experts believe will inform effective policy and on-the-ground conservation.

No plastics detected in seal (Phocidae) stomachs harvested in the eastern Canadian Arctic

Through collaboration with Inuit hunters, we examined the stomach contents of 142 seals (ringed seals [Phoca hispida; n = 135], bearded seals [Erignathus barbatus; n = 6], and one harbour seal [Phoca vitualina; n = 1]) hunted between 2007 and 2019 from communities around Nunavut to assess whether seals in the eastern Canadian Arctic ingest and retain plastics in their stomachs. The seals in this study ranged from juveniles to adults of up to 30 years of age, and 55% of the seals were males. We found no evidence of plastic ingestion in any of the seals suggesting that seals in Nunavut are not accumulating plastics (>425 μm) in their stomachs. These data provide important baseline information for future plastic pollution monitoring programs in the Arctic.