Substituted diphenylamine antioxidants and benzotriazole UV stabilizers in blood plasma of fish, turtles, birds and dolphins from North America

Distribution and trophodynamics of substituted diphenylamine antioxidants and benzotriazole UV stabilizers in a freshwater ecosystem and the adjacent riparian environment

Substituted diphenylamine antioxidants (SDPAs) and benzotriazole UV stabilizers (BZT-UVs) are industrial additives of emerging environmental concern. However, little is known about their environmental fate and bioaccumulation. This study investigated the concentrations of SDPAs and BZT-UVs in the water, sediment and biota samples in the freshwater ecosystem and adjacent riparian environment using Hamilton Harbour in the Great Lakes of North America as a study site. The bioaccumulation factors and trophodynamics of these contaminants were studied using field-collected samples. Eight target SDPAs and two BZT-UVs (2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (UV234) and 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV328)) were frequently detected in the sediment, water and biota samples. UV328 showed significantly greater concentrations in water (0.28-2.8 ng L-1) and sediment (8.3-48 ng g-1, dry weight) than other target contaminants, implying greater contamination of UV328 in Hamilton Harbour. SDPAs exhibited trophic dilution in species living in the water, whereas UV234 was biomagnified in the same samples. No clear trophodynamic trend was found for UV328 for water-respiring species. Air-breathing invertebrates had higher concentrations of both SDPAs and BZT-UVs than water-respiring invertebrates, and biomagnification was observed particularly for adult dragonflies. These results suggest that the trophodynamics of SDPAs and BZT-UVs vary depending on whether the food web is terrestrial or aquatic. Future research should investigate the occurrence and partitioning of SDPAs and BZT-UVs in the air-water interface and evaluate the toxicities of these contaminants in air-breathing species.

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.

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.

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.

Embryonic Exposure to Benzotriazole Ultraviolet Stabilizer 327 Alters Behavior of Rainbow Trout Alevin

Benzotriazole ultraviolet (UV) stabilizers (BUVSs) are used in great quantities during industrial production of a variety of consumer and industrial goods. As a result of leaching and spill, BUVSs are detectable ubiquitously in the environment. As of May 2023, citing concerns related to bioaccumulation, biomagnification, and environmental persistence, (B)UV(S)-328 was recommended to be listed under Annex A of the Stockholm Convention on Persistent Organic Pollutants. However, a phaseout of UV-328 could result in a regrettable substitution because the replacement chemical(s) could cause similar or unpredicted toxicity in vivo, relative to UV-328. Therefore, the influence of UV-327, a potential replacement of UV-328, was investigated with respect to early life development of newly fertilized rainbow trout embryos (Oncorhynchus mykiss), microinjected with environmentally relevant concentrations of UV-327. Developmental parameters (standard length), energy consumption (yolk area), heart function, blue sac disease, mortality, and behavior were investigated. Alevins at 14 days posthatching, exposed to 107 ng UV-327 g-1 egg, presented significant signs of hyperactivity; they moved on average 1.8-fold the distance and at 1.5-fold the velocity of controls. Although a substantial reduction in body burden of UV-327 was observed at hatching, it is postulated that UV-327, due to its lipophilic properties, interfered with neurological development and signaling from the onset of neurogenesis. If these results hold true across multiple taxa and species, a potential contributor to neurodevelopmental disorders might have been identified. These findings suggest that UV-327 poses an unknown hazard to rainbow trout embryos and alevins, rendering UV-327 a potential regrettable substitution to UV-328. However, a qualified statement on a regrettable substitution requires a comparative investigation on the teratogenic effects between the two BUVSs. Environ Toxicol Chem 2024;00:1-10. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

The understudied global experiment of pollution's impacts on wildlife and human health: The ethical imperative for interdisciplinary research

The global impact of pollution on human and wildlife health is a growing concern. The health impacts of pollution are significant and far-reaching yet poorly understood as no one field of research has the practices and methodologies required to encapsulate the diversity of these consequences. This paper advocates that interdisciplinary research is essential to comprehend the full extent of the impact of pollution. Medical and ecological research play a key role in investigating the health consequences of the pollution crisis, yet the wildlife experience is often neglected. This paper outlines how applying advanced techniques and expertise adapted in medical research to wildlife exposed to pollutants offers a unique perspective to understanding the full diversity of impacts to health. The challenges that impede the progress of this research include the lack of support for interdisciplinary research among funding streams, limitations in field-specific techniques, and a lack of communication between researchers from different disciplines. Of awarded funding from major national research councils across Australia, Europe, and the United States of America, only 0.5% is dedicated to pollution focused research. This is inclusive of laboratory equipment, mitigation strategies, quantification of environmental samples and health consequences research. Of that, 0.03% of funding is awarded to explaining the wildlife experience and documenting the health consequences observed despite being model organisms to environmentally and biologically relevant models for pollution exposure. This calls for a coordinated effort to overcome these hurdles and to promote interdisciplinary research in order to fully comprehend the consequences of pollution exposure and protect the health of humans, wildlife, and the environment. An interdisciplinary approach to this problem is timely given the magnitude of negative health consequences associated with exposure, the number of pollutants already present within the environment and the continual development of new compounds.

Assessment of the presence of UV filters and UV stabilizers in stranded dolphin blubber

The presence of ultraviolet filters (UVFs) and stabilizers (UVSs) was evaluated for the first time in the common bottlenose dolphin (Tursiops truncatus). UVFs and UVSs are compounds of growing concern because their effects on the environment are not completely known. UVFs and UVSs are added to personal care products (PCPs), such as cosmetics and products related to sun care and once released to the aquatic ecosystem, marine organisms can bioaccumulate these substances. This work aimed to determine the presence of 12 UVFs and UVSs in cetacean blubber samples to assess the pollution to which these animals of the highest trophic chain levels are exposed due to human activity. Analytical determinations were carried out using a method based on microwave-assisted extraction combined with ultrahigh-performance liquid chromatography and tandem mass spectrometry detection. The developed method was successfully applied to determine the target compounds in the blubber tissues of five necropsied common bottlenose dolphins. Three of the 12 studied compounds, namely 2-ethylhexyl 2-cyano-3,3-diphenylprop-2-enoate (octocrilene, OC), 2-hydroxy-4-methoxybenzophenone (benzophenone 3, BP3) and 3-methylbutyl (E)-3-(4methoxyphenyl) prop-2-enoate (IMC), were detected in several samples. Of the identified compounds, OC was present in all the samples and at the highest concentration within the range from 52.61 ± 18.59 to 108.0 ± 11.32 ng·g-1.

Ubiquity of Amino Accelerators and Antioxidants in Road Dust from Multiple Land Types: Targeted and Nontargeted Analysis

Amino accelerators and antioxidants (AAL/Os), as well as their degradation derivatives, are industrial additives of emerging concern due to their massive production and use (particularly in rubber tires), pervasiveness in the environment, and documented adverse effects. This study delineated their inter-regional variations in road dust collected from urban/suburb, agricultural, and forest areas, and screened for less-studied AAL/O analogues with high-resolution mass spectrometry. 1,3-Diphenylguanidine (DPG; median concentration: 121 ng/g) and N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6PPD-Q; 9.75 ng/g) are the most abundant congeners, constituting 69.7% and 41.4% of the total concentrations of AAL/Os (192 ng/g) and those of AAO transformation products (22.3 ng/g), respectively. The spatial distribution across the studied sites suggests evident human impacts, reflected by the pronounced urban signature and vehicle-originated pollution. Our nontargeted analysis of the most-contaminated road dust identified 16 AAL/O-related chemicals, many of which have received little investigation. Particularly, environmental and toxicological information remains extremely scarce for five out of the 10 most concerning compounds prioritized in terms of their dusty residues and toxicity including 1,2-diphenyl-3-cyclohexylguanidine (DPCG), N,N''-bis[2-(propan-2-yl)phenyl]guanidine (BPPG), and N-(4-anilinophenyl)formamide (PPD-CHO). Additionally, dicyclohexylamine (DChA), broadly applied as an antioxidant in automobile products, had an even greater median level than DPG. Therefore, future research on their health risks and (eco)toxic potential is of high importance.

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.

Investigating the bioaccumulation potential of anionic organic compounds using a permanent rainbow trout liver cell line

Permanent rainbow trout (Oncorhynchus mykiss) cell lines represent potential in vitro alternatives to experiments with fish. We here developed a method to assess the bioaccumulation potential of anionic organic compounds in fish, using the rainbow trout liver-derived RTL-W1 cell line. Based on the availability of high quality in vivo bioconcentration (BCF) and biomagnification (BMF) data and the substances' charge state at physiological pH, four anionic compounds were selected: pentachlorophenol (PCP), diclofenac (DCF), tecloftalam (TT) and benzotriazol-tert-butyl-hydroxyl-phenyl propanoic acid (BHPP). The fish cell line acute toxicity assay (OECD TG249) was used to derive effective concentrations 50 % and non-toxic exposure concentrations to determine exposure concentrations for bioaccumulation experiments. Bioaccumulation experiments were performed over 48 h with a total of six time points, at which cell, medium and plastic fractions were sampled and measured using high resolution tandem mass spectrometry after online solid phase extraction. Observed cell internal concentrations were over-predicted by KOW-derived predictions while pH-dependent octanol-water partitioning (DOW) and membrane lipid-water partitioning (DMLW) gave better predictions of cell internal concentrations. Measured medium and cell internal concentrations at steady state were used to calculate RTL-W1-based BCF, which were compared to DOW- or DMLW-based model approaches and in vivo data. With the exception of PCP, the cell-derived BCF best compared to DOW-based model predictions, which were higher than predictions based on DMLW. All methods predicted the in vivo BCF for diclofenac well. For PCP, the cell-derived BCF was lowest although all BCF predictions underestimated the in vivo BCF by ≥ 1 order of magnitude. The RTL-W1 cells, and all other prediction methods, largely overestimated in vivo BMF, which were available for PCP, TT and BHPP. We conclude that the RTL-W1 cell line can supplement BCF predictions for anionic compounds. For BMF estimations, however, in vitro-in vivo extrapolations need adaptation or a multiple cell line approach.

Biotransformation, metabolic response, and toxicity of UV-234 and UV-326 in larval zebrafish (Danio rerio)

Benzotriazole ultraviolet stabilizers (BUVSs) are emerging pollutants that are widely detected in aquatic ecosystems. While structure-dependent effects of BUVSs are reported, the relationship between biotransformation and toxicity outcomes remains unclear. In this study, zebrafish embryos were exposed to two common BUVSs (UV-234 and UV-326) at 1, 10, and 100 µg/L for up to 7 days. Comparison of their uptake and biotransformation revealed that the bioaccumulation capacity of UV-234 was higher than that of UV-326, while UV-326 was more extensively biotransformed with additional conjugation reactions. However, UV-326 showed low metabolism due to inhibited phase II enzymes, which may result in the comparable internal concentrations of both BUVSs in larval zebrafish. Both BUVSs induced oxidative stress while decreased MDA, suggesting the disturbance of lipid metabolism. The subsequent metabolomic profiling revealed that UV-234 and UV-326 exerted different effects on arachidonic acid, lipid, and energy metabolism. However, both BUVSs negatively impacted the cyclic guanosine monophosphate / protein kinase G pathway. This converged metabolic change resulted in comparable toxicity of UV-234 and UV-326, which was confirmed by the induction of downstream apoptosis, neuroinflammation, and abnormal locomotion behavior. These data have important implications for understanding the metabolism, disposition, and toxicology of BUVSs in aquatic organisms.

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.

Past and future: Urbanization and the avian endocrine system

Urban environments are evolutionarily novel and differ from natural environments in many respects including food and/or water availability, predation, noise, light, air quality, pathogens, biodiversity, and temperature. The success of organisms in urban environments requires physiological plasticity and adjustments that have been described extensively, including in birds residing in geographically and climatically diverse regions. These studies have revealed a few relatively consistent differences between urban and non-urban conspecifics. For example, seasonally breeding urban birds often develop their reproductive system earlier than non-urban birds, perhaps in response to more abundant trophic resources. In most instances, however, analyses of existing data indicate no general pattern distinguishing urban and non-urban birds. It is, for instance, often hypothesized that urban environments are stressful, yet the activity of the hypothalamus-pituitary-adrenal axis does not differ consistently between urban and non-urban birds. A similar conclusion is reached by comparing blood indices of metabolism. The origin of these disparities remains poorly understood, partly because many studies are correlative rather than aiming at establishing causality, which effectively limits our ability to formulate specific hypotheses regarding the impacts of urbanization on wildlife. We suggest that future research will benefit from prioritizing mechanistic approaches to identify environmental factors that shape the phenotypic responses of organisms to urbanization and the neuroendocrine and metabolic bases of these responses. Further, it will be critical to elucidate whether factors affect these responses (a) cumulatively or synergistically; and (b) differentially as a function of age, sex, reproductive status, season, and mobility within the urban environment. Research to date has used various taxa that differ greatly not only phylogenetically, but also with regard to ecological requirements, social systems, propensity to consume anthropogenic food, and behavioral responses to human presence. Researchers may instead benefit from standardizing approaches to examine a small number of representative models with wide geographic distribution and that occupy diverse urban ecosystems.

Flower-like molybdenum disulfide/cobalt ferrite composite for the extraction of benzotriazole UV stabilizers in environmental samples

Benzotriazole UV stabilizers (BUVSs) are a class of emerging contaminants of concern; the development of rapid and convenient monitoring method for these trace-level pollutants in waters is of crucial significance in environmental science. Here, a novel magnetic flower-like molybdenum disulfide/cobalt ferrite nanocomposite (MoS₂/CoFe₂O₄) was synthesized by hydrothermal reaction. Compared with the conventional Fe₃O₄-based magnetic composites, the proposed material just required a minimum consumption of Co/Fe towards the equivalent of MoS₂ while providing superior magnetization performance. Taking advantages of high adsorption capacity, extraordinary stability, and repeatability in construction, MoS₂/CoFe₂O₄ was applied to the extraction to BUVSs. The enrichment factors of three BUVSs were in the range 164-193 when 20 mL of environmental water sample was loaded on 40 mg of the adsorbent. MoS₂/CoFe₂O₄ could be regenerated and recycled at least 10 cycles of adsorption/desorption with recoveries of 80.1-111%. The method of MoS₂/CoFe₂O₄-based extraction coupled with high-performance liquid chromatography-variable wavelength detector was applied to the monitoring of BUVSs in seawater, lake water, and wastewater, which gave detection limits (S/N = 3) of 0.023-0.030 ng·mL^-1 and recoveries of 80.1-110%. The intra-day and inter-day precisions (relative standard deviation, RSDs, n = 3) were in the range 1.6-7.5% and 3.2-11.5%, respectively. The approach is an alternative for efficient and sensitive extraction and determination of trace-level environmental pollutants in waters.

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.

Effects of dietary 2-(2H-benzotriazol-2-yl)-4-methylphenol (UV-P) exposure on Japanese medaka (Oryzias latipes) in a short-term reproduction assay

Benzotriazole ultraviolet stabilizers (BZT-UVs) are added to various products to prevent damage caused by UV light and have emerged as contaminants of concern. Although BZT-UVs are detected in aquatic biota globally, few studies have assessed their potential toxic effects. The objective of the present study was to assess effects of 2-(2H-Benzotriazol-2-yl)-4-methylphenol (UV-P) on reproductive success of Japanese medaka (Oryzias latipes) in a standard 21-day reproduction assay. Japanese medaka were exposed to dietary UV-P at concentrations of 0, 36, 158, and 634 ng UV-P/g food, for a total of 28 days which included 7 days of exposure prior to the start of the 21-day reproduction assay. No significant effect on egg production or fertilization success was observed. Abundances of transcripts of erα, vtgI, cyp1a, or cyp3a4 were not significantly different in livers from male or female fish exposed to UV-P. However, abundances of transcripts of cyp11a and cyp19a were significantly lower in gonads from female fish. There was a trend of increasing concentrations of E2 and a non-significant increase of T in the 634 ng/g treatment in plasma from female fish exposed to UV-P. Concentrations of 11-KT were unchanged in plasma from males exposed to UV-P. These responses suggest weak perturbation of steroidogenesis, consistent with an antiandrogenic mode of action. However, this perturbation was insufficient to impair reproductive performance. Metabolomics analysis of female livers suggests altered concentrations of various metabolites and biological pathways, including glutathione metabolism, suggesting that UV-P might cause responses related to oxidative stress or phase II metabolism. However, metabolomics revealed no obvious mechanism of toxicity. Overall, results of this study indicate that dietary exposure to UV-P up to 634 ng/g food does not significantly impact reproductive performance of Japanese medaka but impacts on steroidogenesis could indicate a potential mechanism of toxicity which might lead to reproductive impairment in more sensitive species.

Specific-accumulation and trophic transfer of UV filters and stabilizers in marine food web

The occurrence and distribution of benzotriazole UV stabilizers (BUVs) and UV filters in marine environments (sediment and seawater) and 20 biota species in the South Korea were investigated to assess their transfer through the marine food web. The total concentrations in the seawater samples were 4.73-8.60 ng/L for BUVs and 1.20-4.88 ng/L for UV filters; while, the total concentrations in the sediment samples were 0.581-6.62 ng/g dw for BUVs and 1.05-6.79 ng/g dw for UV filters, respectively. The total concentrations of BUVs and UV filters were a little higher in benthic invertebrates (BUVs: 131 ng/g lipid weight [lw], UV filters: 41.7 ng/g lw) than fish (BUVs: 99.2 ng/g lw, UV filters: 28.0 ng/g lw) but there were no statistical differences (Mann-Whitney U test, p > 0.05). UV-326 was dominant (fish: 37.9%, benthic invertebrate: 48.7%) of the total BUVs. While, benzophenone-3 (fish: 34.1%, benthic invertebrate: 40.8%) and ethylhexyl methoxy cinnamate (fish: 41.0%, benthic invertebrate: 37.8%) were the dominant UV filters. The bioaccumulation factor and trophic magnification factor indicated that UV-326 can both bioaccumulate and biomagnify (bioaccumulation factor >5000 and biota-sediment accumulation and trophic magnification factors >1). Several other BUVs were found to be able to either bioaccumulate (UV-320, UV-P, UV-329, and UV-234) or biomagnify (UV-327 and UV-928). Most of the analyzed UV filters were found not to be likely to bioaccumulate.

Degradation of Benzotriazole UV Stabilizers in PAA/d-Electron Metal Ions Systems-Removal Kinetics, Products and Mechanism Evaluation

Benzotriazole UV stabilizers (BUVs) have gained popularity, due to their absorption properties in the near UV range (200–400 nm). They are used in the technology for manufacturing plastics, protective coatings, and cosmetics, to protect against the destructive influence of UV radiation. These compounds are highly resistant to biological and chemical degradation. As a result of insufficient treatment by sewage treatment plants, they accumulate in the environment and in the tissues of living organisms. BUVs have adverse effects on living organisms. This work presents the use of peracetic acid in combination with d-electron metal ions (Fe²⁺, Co²⁺), for the chemical oxidation of five UV filters from the benzotriazole group: 2-(2-hydroxy-5-methylphenyl)benzotriazole (UV-P), 2-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)-4-methylphenol (UV-326), 2,4-di-tert-butyl-6-(5-chloro-2H-benzotriazol-2-yl)phenol (UV-327), 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV-328), and 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (UV-329). The oxidation procedure has been optimized based on the design of experiments (DoE) methodology. The oxidation of benzotriazoles follows first order kinetics. The oxidation products of each benzotriazole were investigated, and the oxidation mechanisms of the tested compounds were proposed.

Phase partitioning, transport and sources of Benzotriazole Ultraviolet Stabilizers during a runoff event

Benzotriazole Ultraviolet Stabilizers (BT-UVs) are ubiquitous in the environment, given their wide use as additives in consumer products. Their bio-accumulative and toxic properties are increasingly being scrutinised, evinced by the recent proposition to add UV328 to the Stockholm Convention on Persistent Organic Pollutants. Here, we measured concentrations of six BT-UVs in the dissolved and particulate phases of stream water collected from an urban and rural stream during a runoff event. Under baseflow conditions, the less hydrophobic BT-UVs were present at low concentrations in the dissolved phase, while much higher loads of particulate BT-UVs occurred during stormflow, especially in the urban creek. Time-weighted average BT-UV concentrations were up to 4 times higher in the urban than in the rural creek. BT-UVs were found to be prevalent in water obtained from laundering textiles, which plausibly constitutes a major portion of domestic wastewater, and can serve as a BT-UV source to aquatic waterways. However, the observed dilution of a sewage tracer during the run-off event suggests that unregulated wastewater seepage is not responsible for the high BT-UV loads in storm water. High levels of UV328 and UV234 were detected in a select few plastic debris items collected from the urban watershed and in artificial turf grass, respectively. Whereas this may allow for the leaching of those BT-UVs into the creek, most plastic debris is more likely a sink than a source of BT-UVs. The observed input of particle-bound BT-UVs at the onset of the rain event indicates that most of the BT-UVs reach the creek with contaminated particles that had built up on surfaces during the antecedent dry period. UV328 was the dominant BT-UV in those particles. If such particle build-up occurs on road surfaces, it may suggest that the use of UV328 in automotive applications contributes to their presence in urban storm water.

Tissue-Specific Accumulation, Biotransformation, and Physiologically Based Toxicokinetic Modeling of Benzotriazole Ultraviolet Stabilizers in Zebrafish (Danio rerio)

Benzotriazole ultraviolet stabilizers (BUVSs) are high-production-volume chemicals with ubiquitous occurrence in the aquatic environment. However, little is known about their bioconcentration and biotransformation, and physiologically based toxicokinetic (PBTK) models for BUVSs are lacking. This study selected six BUVSs for which experiments were performed with zebrafish (Danio rerio) exposed to two different levels (0.5 and 10 μg·L^-1). Higher kinetic bioconcentration factors (BCFs) were observed at the lower exposure level with environmental relevance, with BCF of 3.33 × 10³ L·kg^-1 for 2-(2-hydroxy-3,5-di-tert-butylphenyl)-5-chlorobenzotriazole (UV-327). This phenomenon was interpreted by a nonlinear adsorption mechanism, where binding with specific protein sites contributes to bioconcentration. Muscle exhibited the lowest accumulation, in which depuration half-life of UV-327 was 19.5 d. In kidney, muscle, ovary, gill, and skin, logBCF increased with increase in log K_OW of the BUVSs until log K_OW was ca. 6.5, above which logBCF decreased. However, the trend was not observed in the liver and intestine. Six biotransformation products were identified and mainly accumulated in the liver and intestine. Considering the nonlinear adsorption mechanism in the PBTK model, the prediction accuracy of the model was improved, highlighting the binding of xenobiotics with specific protein sites in assessing the bioconcentration of chemicals for their risk assessment.

A Comparative Test on the Sensitivity of Freshwater and Marine Microalgae to Benzo-Sulfonamides, -Thiazoles and -Triazoles

The evaluation of the ecotoxicological effects of water pollutants is performed by using different aquatic organisms. The effects of seven compounds belonging to a class of widespread contaminants, the benzo-fused nitrogen heterocycles, on a group of simple organisms employed in reference ISO tests on water quality (unicellular algae and luminescent bacteria) have been assessed to ascertain their suitability in revealing different contamination levels in the water, wastewater, and sediments samples. Representative compounds of benzotriazoles, benzothiazoles, and benzenesulfonamides, were tested at a concentration ranging from 0.01 to 100 mg L−1. In particular, our work was focused on the long-term effects, for which little information is up to now available. Species-specific sensitivity for any whole family of pollutants was not observed. On average, the strongest growth rate inhibition values were expressed by the freshwater Raphidocelis subcapitata and the marine Phaeodactylum tricornutum algae. R. subcapitata was the only organism for which growth was affected by most of the compounds at the lowest concentrations. The tests on the bioluminescent bacterium Vibrio fisheri gave completely different results, further underlining the need for an appropriate selection of the best biosensors to be employed in biotoxicological studies.

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.

Human metabolism and kinetics of the UV absorber 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV 328) after oral administration

2-(2H-Benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV 328; CAS: 25973-55-1) is an ultraviolet light (UV) absorber which belongs to the class of hydroxy phenol benzotriazoles. Therefore, UV 328 is added to plastics and other polymers due to its photostability to prevent discoloration and prolong product stability which may result in an exposure of consumers. However, information about the toxic effects on humans and the human metabolism are still lacking. In the present study, human metabolism pathways of UV 328 and its elimination kinetics were explored. For that purpose, three healthy volunteers were orally exposed to a single dose of 0.3 mg UV 328/kg bodyweight. UV 328 and its metabolites were investigated in blood and urine samples collected until 48 and 72 h after exposure, respectively. Thereby, previously published analytical procedures were applied for the sample analysis using dispersive liquid–liquid microextraction and subsequent measurement via gas chromatography coupled to tandem mass spectrometry with advanced electron ionization. UV 328 was found to be oxidized at its alkyl side chains leading to the formation of hydroxy and/or oxo function with maximum blood concentrations at 8–10 h after exposure for UV 328-6/3-OH, UV 328-4/3-OH and UV 328-4/3-CO. In contrast, a plateau for UV 328-4/3-CO-6/3-OH levels was reached around 10 h post-dosage. The highest blood levels were found for native UV 328 at 8 h after ingestion. Furthermore, biphasic elimination kinetics in blood were revealed for almost all detected metabolites. UV 328 and its metabolites did not occur in blood as conjugates. The renal elimination kinetics were very similar with the kinetics in blood. However, the prominence of the metabolites in urine was somewhat different compared to blood. In contrast, mostly conjugated metabolites occurred for renal elimination. In urine, UV 328-4/3-CO-6/3-OH was found to be the most dominant urinary biomarker followed by UV 328-6/3-OH and UV 328-4/3-OH. In total, approximately 0.1% of the orally administered dose was recovered in urine within 72 h. Although high levels of UV 328 in blood proved good resorption and high systemic availability of the substance in the human body, the urine results revealed a rather low quantitative metabolism and urinary excretion rate. Consequently, biliary excretion as part of the enterohepatic cycle and elimination via feces are assumed to be the preferred pathways instead of renal elimination.

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).

The Roles of Sono-induced Nitrosation and Nitration in the Sono-degradation of Diphenylamine in Water: Mechanisms, Kinetics and Impact Factors

The potential risks of sono-induced nitrosation and nitration side reactions and consequent toxic nitrogenous byproducts were first investigated via sono-degradation of diphenylamine (DPhA) in this study. The kinetic models for overall DPhA degradation and the formation of nitrosation byproduct (N-nitrosodiphenylamine, NDPhA) and nitration byproducts (2-nitro-DPhA and 4-nitro-DPhA) were well established and fitted (R² > 0.98). Nitrosation contributed much more than nitration (namely, 43.3 - 47.3 times) to the sono-degradation of DPhA. The contribution of sono-induced nitrosation ranged from 0.4 to 56.6% at different conditions. The maximum NDPhA formation rate and the contribution of sono-induced nitrosation were obtained at 600 and 200 kHz, respectively, as ultrasonic frequencies at 200 to 800 kHz. Both NDPhA formation rate and the contribution of sono-induced nitrosation increased with increasing power density, while decreased with increasing initial pH and DPhA concentration. PO₄^3-, HCO₃^-, NH₄⁺ and Fe²⁺ presented negative impacts on sono-induced nitrosation in order of HCO₃^- >> Fe²⁺ > PO₄^3- > NH₄⁺, while Br^- exhibited a promoting effect. The mechanism of NDPhA formation via sono-induced nitrosation was first proposed.

Bioaccumulation and physiological responses of the turtle Chelydra serpentina exposed to polychlorinated biphenyls during early life stages

Despite the North American production ban of polychlorinated biphenyls (PCBs), PCBs are ubiquitous in the environment and in wildlife tissues. Chelydra serpentina serpentina (common snapping turtle) have been used as environmental indicators of PCB pollution upwards of 40 years given their high site fidelity and high trophic position. Despite their long use as indicators of PCB contamination, the effects of PCBs in reptiles remain largely unknown. In this study, we performed two experiments to assess i) bioaccumulation and ii) toxicity of PCBs to 1-month-old C. s. serpentina, to aid in interpretation of PCB burdens. Food pellets were spiked at an environmentally relevant concentration (0.45 μg/g) of the PCB mixture Aroclor 1254 to model hepatic bioaccumulation and depuration, through feeding, for 31 days and clean food for 50 days, respectively. No significant differences in PCB concentrations were observed in liver tissue over the course of the experiment, suggesting that juvenile turtles can likely metabolize low environmentally occurring concentrations of PCBs. Additionally, a dose-response experiment, performed to determine hepatic toxicity and bioaccumulation in juvenile C. s. serpentina, showed a 1.8-fold increase in hepatic expression of cyp1a when fed A1254-spiked pellets (12.7 μg/g; range 0-12.7 μg/g). This gene induction correlates with the significant increase of group 3 PCB congeners measured in the turtle liver, which are known to be metabolized by CYP1A. This study indicates that C. s. serpentina may be a good environmental indicator for PCBs, while more research is needed to assess the effects of body burdens in wild C. s. serpentina.

Dispersive liquid-liquid microextraction (DLLME) and external real matrix calibration for the determination of the UV absorber 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV 328) and its metabolites in human blood

2-(2H-Benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV 328; CAS: 25973-55-1) is a benzotriazole ultraviolet light (BUV) absorber which is applied to plastics and other organic substances to prevent discoloration and enhance product stability. Therefore, UV 328 is frequently used as a plastic additive and may lead to an exposure of consumers. For a reliable assessment of UV 328 metabolism, an analytical method applying dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography tandem mass spectrometry and advanced electron ionization was developed which allows the determination of UV 328 and six of its metabolites in human whole blood. Sample preparation was optimized with respect to DLLME parameters. A critical aspect of the procedure was the application of spiked human blood for calibration, which proved to be essential for achieving accurate results. Validation of the method resulted in limits of detection of 0.1 μg/L for all analytes. Variation coefficients ranged from 2 to 9% for intraday precision and from 3 to 11% for interday precision. Furthermore, relative recovery rates between 80 and 100% were calculated. Afterwards, the procedure was successfully applied to blood samples collected from a volunteer orally exposed to a single dose of UV 328. The method proved to be highly sensitive, repeatable and robust for all compounds and may further be used for studies to elucidate the human metabolism and kinetics of UV 328 and for biomonitoring of specific, environmental and occupational exposure to this UV stabilizer.

Occurrence of benzotriazole UV stabilizers in coastal fishes

Chemicals added in personal care products are of emerging concern because their fate and their effect on the environment is not completely known. Benzotriazole UV stabilizers (BUVSs) are compounds used in different cosmetic products, which may reach the marine environment through marine discharge from treated waters or directly from bathing areas. Once released into the aquatic ecosystem, BUVSs can be bioaccumulated by aquatic organisms. To identify the human exposure risk, it is important to have suitable analytical methods to determine the presence of BUVSs in these organisms. Because of the complexity of such a biological matrix, selective extraction and detection techniques are required to isolate and quantify these kinds of pollutants at trace levels. In the present work, we optimized a method based on microwave-assisted extraction combined with ultra-high performance liquid chromatography and mass spectrometry detection to determine six benzotriazole compounds in fish samples. The absolute extraction yields provided by the proposed method were higher than 40% for most compounds, with intra-day and inter-day relative standard deviations ranging from 0.27 to 6.06 and 1.12-21.3%, respectively. The limits of quantification were in the range of 1.13-9.66 ng g^-1 (dry weight). The method was applied to the study of three species of fish (Boops boops, Sphyraena viridensis, Sphoeroides marmoratus) that were collected close to three marine outfalls of treated waters on the Gran Canaria Island (Spain) for two years. Four of the six studied compounds, UV-326, UV-328, UV-329 and UV-360, were found with concentrations ranging from 1.34 ng g^-1 to 45.6 ng g^-1 (dry weight).

[Determination of UV-327 and UV-328 in mouse plasma by high performance liquid chromatography]

OBJECTIVE

To establish a high performance liquid chromatography (HPLC) method for the determination of ultraviolet (UV) absorbers UV-327 and UV-328 in mouse plasma.

METHODS

N-hexane-acetone (volume ratio 1 ∶1) was added to a mouse plasma sample as the extraction solvent for vortex extraction, and the supernatant was dried at 50 ℃ with nitrogen. Thereafter the residue was redissolved with methanol, centrifuged and filtered. The separation was performed on a Waters SymmetryC₁₈ column (250 mm×4.6 mm, 5 μm), and the concentrations of UV-327 and UV-328 in the mouse plasma were determined by HPLC with an UV detector. The elution was isocratic at a flow rate of 1.0 mL/min with a mobile phase composed of 100% methanol, and the UV detection wavelength was 340 nm. The retention time was used for qualitative analysis, and the internal standard method was used for quantitative analysis using UV-320 as the internal standard.

RESULTS

The calibration curves of UV-327 and UV-328 were linear with correlation coefficients of 0.999 7 over the concentration range of 0.05 to 10.0 mg/L. The limit of detection was 0.01 mg/L, and the limit of quantitation was 0.03 mg/L. The average recoveries at low, medium and high three concentrations (0.50, 1.00, 2.00 mg/L) in the mouse plasma were 91.7%-101.0% for UV-327, and 97.5%-103.9% for UV-328. The intra-day precisions (n=6) of UV-327 were 2.9%-6.6%, and 2.7%-7.4% for UV-328. The inter-day precisions (n=3) of UV-327 were 6.0%-9.3%, and 6.6%-8.6% for UV-328. The extraction recoveries of UV-327 were 98.8%-103.8%, and 99.8%-100.9% for UV-328. The measured relative deviations of UV-327 in the mouse plasma samples placed at room temperature for 6 hours and -40 ℃ for 15 days were 0.9%-3.5% and 7.4%-15.0%, and the measured relative deviations of UV-328 were 2.0%-4.3% and 2.1%-13.8%, respectively. The mouse plasma samples could be stored at room temperature for 6 hours at least and -40 ℃ for 15 days at three spiked concentration levels.

CONCLUSION

The method was simple and fast with high accuracy, precision and sensitivity, and could be applied to the determination of UV-327 and UV-328 in mouse plasma.

Uptake and transformation of decabromodiphenyl ether in different rice cultivars: Evidence from a carbon-14 study

The differences of PBDE absorption, accumulation, and metabolism in different cultivars of the same crop are rarely explored. This study used ¹⁴C tracing to fully demonstrate the uptake and transformation of soil-borne BDE209 in three rice cultivars, including two indica (HHZ and YD1) and one japonica cultivars (NJ3). Results showed that about 6.9, 17.2, and 17.4% of the applied ¹⁴C-BDE209 were transformed to ¹⁴C-metabolites in soils planted with HHZ, YD1, and NJ3, respectively. The ¹⁴C-BDE209 and its ¹⁴C-metabolites in soil could be absorbed by the rice and gradually transported to its root, stem, leaf, and grain, with the total whole-plant uptake of 8.52, 4.55 and 3.43 nmol for HHZ, YD1, and NJ3, respectively. The cultivar of HHZ had the greatest whole-plant ¹⁴C absorption but the lowest ΣPBDEs residues in its grain, with the ΣPBDEs of 421.8, 454.2 and 967.0 ng g^-1 for HHZ, YD1, and NJ3, respectively. BDE-209 accounted for 90%, 31% and 50% of the ΣPBDEs in the grain from HHZ, YD1, and NJ3, respectively. The estimated daily intake (EDI) amounts of ΣPBDEs were 928, 1056, and 2675 ng kg^-1 bw d^-1 via consuming rice grains from HHZ, YD1, and NJ3, respectively, which were below the safe threshold limits for human consumption. This study proved the different BDE-209 absorption, accumulation and transformation in different rice cultivars, which potentially suggests the need of considering cultivar differences in assessing the dietary risks of PBDEs.

Piece-by-piece analysis of additives and manufacturing byproducts in plastics ingested by seabirds: Implication for risk of exposure to seabirds

The risk of marine organisms ingesting plastics has become a growing concern due to hazard chemicals in plastics. To identify compounds to which seabirds potentially have substantial exposure, 194 plastics fragments and pellets ingested by seabirds, i.e., northern fulmars from the Faroe Islands, and laysan albatross and black-footed albatross from Mukojima Island, were analyzed piece by piece. Four kinds of UV stabilizers, 2 brominated flame retardants, and styrene oligomers were detected at detection frequencies of 4.6%, 2.1%, and 2.1%, respectively. Concentrations ranging from not detected (n.d.) - 1700 μg/g were measured for UV stabilizers, n.d. - 1100 μg/g for flame retardants, and n.d. - 3200 μg/g for styrene oligomers. We found that these chemicals could be retained in plastics during drifting and fragmentation in the ocean and transported to seabirds. This type of transport via plastics can be direct pathway that introduces hazardous compounds to marine organisms.

Oxidative phase I metabolism of the UV absorber 2-(2H-benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV 328) in an in vitro model with human liver microsomes

2-(2H-Benzotriazol-2-yl)-4,6-di-tert-pentylphenol (UV 328, CAS: 25973-55-1) is an ultraviolet light (UV) absorber which is used as an additive for plastics and other polymeric substances to prevent the host material from light induced degradation reactions. However, no information about human exposure, metabolism and kinetics is available for this substance so far. Therefore, in vitro experiments with human liver microsomes were performed to derive oxidative phase I metabolites of UV 328 in an explorative approach using liquid-chromatography coupled with tandem mass spectrometry. Initially, a suspect screening mode was applied to the incubated samples. Six metabolites with hydroxy or oxo groups as well as a metabolite carrying both hydroxy and carbonyl moieties at the alkyl side chains were postulated and custom synthesized as reference standards. Afterwards, the results were verified in a target screening approach. Thereby, five of the six investigated analyte structures were confirmed. Quantitative estimations of the generated transformation products revealed 2-(2H-benzotriazol-2-yl)-6-(3-hydroxy-2-methylbutan-2-yl)-4-(tert-pentyl)phenol (UV 328-6/3-OH), 2-(2H-benzotriazol-2-yl)-4-(3-hydroxy-2-methylbutan-2-yl)-6-(tert-pentyl)phenol (UV 328-4/3-OH) and 2-(2H-benzotriazol-2-yl)-4-(2-methylbutan-3-on-2-yl)-6-(3-hydroxy-2-methylbutan-2-yl)phenol (UV 328-4/3-CO-6/3-OH) as most promising parameters. In summary, oxidation of both alkyl side chains at the phenol moiety was proven, but no metabolic transformations at the benzotriazole moiety were observed.

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

Substituted diphenylamine antioxidants (SDPAs) and benzotriazole UV stabilizers (BZT-UVs) are contaminants of emerging environmental concern. However, little is known about the occurrence of these contaminants in the Arctic. In this study, we investigated the levels of 11 SDPAs and 6 BZT-UVs in livers and eggs of two seabird species, the black-legged kittiwake (Rissa tridactyla) and northern fulmar (Fulmarus glacialis), as well as the liver of ringed seals (Pusa hispida) from Canadian high- and sub-Arctic sites. The concentrations of ΣSDPAs in seabird livers (median 336 pg g^-1, wet weight (ww)) were significantly higher than the eggs (median 24 pg g^-1, ww) and the seal livers (median 38 pg g^-1, ww), suggesting liver was a primary tissue of SDPA accumulation in seabirds and that seabirds were at greater risk of exposure to SDPAs than marine mammals in the Arctic. The predominant SDPA was monostyryl octyl-diphenylamine and this compound was detected in every seabird and seal sample, indicating the widespread distribution of this contaminant in Arctic food webs. Unlike SDPAs, the detection rate and concentrations of BZT-UVs in seals were higher than in seabirds. The compound 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol (UV329) or its isomer 2-(2H-benzotriazol-2-yl)-4-(tert-butyl)-6-(sec-butyl) phenol (UV350) was the predominant BZT-UVs in seals, with the concentrations of ΣBZT-UVs between <method quantification limits and 1.66 × 10⁴ pg g^-1 (ww) (median: 2.36 × 10³ pg g^-1, ww). This is the first report of the different distribution patterns of SDPAs and BZT-UVs in wildlife from Canadian Arctic sites.