Benzotriazole UV 328 and UV-P showed distinct antiandrogenic activity upon human CYP3A4-mediated biotransformation

Development of an analytical method and risk characterization for benzotriazole ultraviolet stabilizers in various foods

This study developed and validated an analytical method for quantifying benzotriazole ultraviolet stabilizers (BUVSs) in various foods commonly consumed in Korea, addressing a critical gap in the monitoring of these emerging contaminants in food matrices. The validation results of this gas chromatography-mass spectrometry method demonstrated high specificity, sensitivity, and precision, with limits of detection as low as 0.008-0.040 ng/g across various food types. Among the tested foods, BUVS contamination was highest in fatty matrices, with beef, eel, and mackerel showing elevated levels of UV-326, UV-327, and UV-328. Exposure assessments using dietary consumption data from KNHANES revealed that the average dietary intake of BUVSs posed low health risks, as margins of exposures exceeded the safety threshold of 100. This study emphasizes the importance of ongoing monitoring of persistent organic pollutants in high-fat and other food products to reduce potential bioaccumulation risks, ensuring food safety and public health protection.

Unveiling the effects of micro and nano plastics in embryonic development

The improper disposal and degradation of plastics causes the formation and spread of micro and nano-sized plastic particles in the ecosystem. The widespread presence of these micro and nanoplastics leads to their accumulation in the biotic and abiotic components of the environment, thereby affecting the cellular and metabolic functions of organisms. Despite being classified as xenobiotic agents, information about their sources and exposure related to reproductive health is limited. Micro and nano plastic exposure during early developmental stages can cause abnormal embryonic development. It can trigger neurotoxicity and inflammatory responses as well in the developing embryo. In embryonic development, a comprehensive study of their role in pluripotency, gastrulation, and multi-differentiation potential is scarce. Due to ethical concerns associated with the direct use of human embryos, pluripotent cells and its 3D in vitro models (with cell lines) are an alternative source for effective research. Thus, the 3D Embryoid body (EB) model provides a platform for conducting embryotoxicity and multi-differentiation potential research. Pluripotent stem cells such as embryonic and induced pluripotent stem cells derived embryoid bodies (EBs) serve as a robust 3D in vitro model that mimics characteristics similar to that of human embryos. Thus, the 3D EB model provides a platform for conducting embryotoxicity and multi-differentiation potential research. Accordingly, this review discusses the significance of 3D in vitro models in conducting effective embryotoxicity research. Further, we also evaluated the possible sources/routes of microplastic generation and analyzed their surface chemistry and cytotoxic effects reported till date.

Bioaccumulation and trophic transfer of benzotriazole UV stabilizers in an aquatic food web of a drinking water reservoir: Combining field investigation with biological pathway modelling

Benzotriazole ultraviolet stabilizers (BZT-UVs), applied in many commodities and industrial products, are frequently detected in the aquatic environment. However, the bioaccumulation and trophic transfer of BZT-UVs in the food web of drinking water reservoirs are rarely investigated. The bio-accumulative characteristics and trophic transfer of eight BZT-UVs in the aquatic organisms in Miyun Reservoir, Beijing, China, were studied by integrating contaminant measurements and biological pathway modelling. The sum concentration of BZT-UVs in the biota samples ranged from 8.45 to 57.8 ng/g dry weight (dw), with a median of 19.7 ng/g dw. UV-327 and UV-P were predominant in aquatic organisms, mutually accounting for more than 50 % of the massive contents of all BZT-UVs. BZT-UVs were accumulated in the liver and kidney in most fish species, especially for UV-327, UV-328 and UV-P. UV-328 exhibited the potential of trophic magnification in the aquatic food web, while UV-327 and UV-P were trophic dilution. Gill respiration was the major biological pathway for BZT-UV uptake in fish. As predicted by biological pathway model, modulating of the fish species in reservoirs, such as replacement of bighead carp by silver carp in fish stocking, may affect the flow of trophic transfer and mitigate the pollution level of BZT-UVs in the entire food web.

Toxicokinetics of benzotriazole UV stabilizer UV-P in humans after single oral administration

UV-P (2-(2H-Benzotriazol-2-yl)-p-cresol) is used as an ultraviolet (UV) light absorber in coating products, paints, adhesives, and sealants. Due to its widespread industrial and consumer uses, human exposure to UV-P is conceivable. In the study presented herein, initial data on its human in vivo metabolism were obtained for three study participants after single oral administration of 0.3 mg of UV-P/kg body weight. Urine and blood samples of two volunteers were collected up to 48 h after exposure. The third study participant donated urine and blood samples up to 72 h. Maximum levels of UV-P in blood of 184 ± 36 µg/l (85 ± 3% as conjugates) were reached 2.4 ± 1.2 h post-exposure. Maximum excretion rates of UV-P in urine of 2896 ± 884 µg/h (completely conjugated) were reached 3.5 ± 1.1 h post-exposure. 37.2 ± 5.4% of the orally administered dose of UV-P was recovered in urine within 48 h post-exposure. The present study provides insight into the complex absorption, distribution, metabolism, and elimination (ADME) processes of benzotriazole UV stabilizers (BUVS). The study also demonstrates differences in the ADME between sterically hindered BUVS, such as UV-327 and UV-328, and sterically unhindered BUVS, such as UV-P, in which the phenolic hydroxyl group is readily accessible for conjugation with glucuronic acid or sulfate.

Benzotriazole ultraviolet stabilizers in the environment: A review of occurrence, partitioning and transformation

Benzotriazole ultraviolet stabilizers (BUVSs) are widely used as industrial additives to protect products from photoaging and are present in a variety of environmental matrices and organisms. It raised significant concerns that BUVSs are emerging pollutants with persistence, bioaccumulation and toxicity, of which 2-(3, 5-di-tert-amyl-2-hydroxyphenyl) benzotriazole (UV-328) has been recently listed in Annex A of the Stockholm Convention Persistent Organic Pollutants (POPs) list. A comprehensive understanding of the occurrence, partitioning and transformation of BUVSs in the environment is the basis for their environmental exposure and risk studies. However, the occurrence, partitioning and transformation of BUVSs are scarcely reviewed. In this paper, the environmental occurrence of BUVSs in various matrices, including water-suspended particulate matter and sediment, soil and dust, sludge, as well as biota, were summarized. Solid matrices and organisms are predominant reservoirs for BUVSs rather than waters, but there is a lack of systematical summary on the sorption/partitioning studies of BUVSs in abiotic phases and organisms. This paper analyzed and reviewed the possible sorption/partitioning processes and mechanisms. It was found that the partitioning is dependent on the hydrophobicity of BUVSs, environmental conditions and the organic carbon contents, and the bioaccumulation is also biota-species dependent. To further assess the potential risks of BUVSs, more progress has been made in the study of transformation of BUVSs. Focusing on the most important transformation processes in the environment, involving photodegradation, chemical degradation, biodegradation and metabolism in biota, the probable transformation pathways and mechanisms of BUVSs were summarized. It was emphasized that the hydrophobicity and toxicity of metabolites should not be overlooked. Finally, the future research direction was prospected from contaminant remediation and health risk perspectives. This paper provides fundamental knowledge of the environmental behavior of BUVSs, and will facilitate the research of environmental exposure and risk assessment of BUVSs.

Presence of benzotriazole ultraviolet stabilizers in human urine

Health exposure to benzotriazole ultraviolet stabilizers (BUVSs) may pose diverse toxic impacts on health. Presently, the occurrence of BUVSs in human urine remains inadequately understood. This study analyzed 13 kinds of BUVSs in human urine (n = 182) from the general Chinese adult participants. Totally, nine BUVSs were measurable in these human urine samples. Among the detected BUVSs, 2-(2H-benzotriazol-2-yl)-p-cresol (UV-P) was the most predominant BUVS in the human urine, with the mean concentration of 1.6 μg/g creatinine ( Collapse

Key Words

• Benzotriazole ultraviolet stabilizers
• Human exposure
• Human urine
• UV-326
• UV-328

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MESH Headings

• Humans
• Male
• Female
• Triazoles/urine
• Adult
• Middle Aged
• Young Adult
• Aged
• Ultraviolet Rays
• China
• Environmental Pollutants/urine
• Biological Monitoring/methods

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Grants Collapse

Affiliation(s)

Weili Mao Department of Pharmacy, Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou People's Hospital, Quzhou, Zhejiang, 324000, 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; Innovation Research Center of Advanced Environmental Technology, Eco-Industrial Innovation Institute ZJUT, Quzhou, Zhejiang, 324400, 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
Kaili Mao Department of Pharmacy, Quzhou Affiliated Hospital of Wenzhou Medical University, Quzhou People's Hospital, Quzhou, Zhejiang, 324000, PR China.

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Insights into the uptake, accumulation, and metabolism of UV-328 in lettuce (Lactuca sativa L.) and radish (Raphanus sativus L.)

2-(2H-benzotriazole-2yl)-4,6-di-t-pentylphenol (UV-328), a newly listed persistent organic pollutant (POP) under the Stockholm Convention, has garnered significant attention. It is imperative to understand the uptake, translocation and metabolic pathways of UV-328 in plants to assess its bioaccumulation capacity and potential human health risks. In this study, the absorption, accumulation, and metabolic characteristics of UV-328 in lettuce (Lactuca sativa L.) and radish (Raphanus sativus L.) were assessed by hydroponic experiments. In the hydroponics experiment, UV-328 was significantly absorbed by the roots of the plants, with average root concentration factors (RCFs) ranging from 58.5 to 400 mL/g for lettuce and 84.4-154 mL/g for radish. However, UV-328 was poorly translocated from roots to shoots, with a translocation factor (TF) below 0.055. Furthermore, UV-328 underwent transformation and metabolism within the plant. Utilizing a nontarget screening strategy, fourteen phase I metabolites of UV-328 were firstly identified. The metabolic pathways of UV-328 in plants including hydroxylation, demethylation, oxidation, acetylation and deoxygenation were also suggested. It was worth noting that UV-328 has a significant adverse impact on plant growth and quality. The concentration of chlorophyll in plants exposed to UV-328 was significantly reduced, as were the concentrations of water, flavonoids, vitamin C and amino acids.

Exposure Assessment of Benzotriazole Ultraviolet Absorbers in Plastic Sports Field Dust and Indoor Dust: Are Plastic Sports Fields High Exposure Scenarios?

Benzotriazole ultraviolet absorbers (BUVs), as emerging contaminants of extensive use, especially in plastic sports fields, have aroused increasing concern due to their potential human and environmental impacts. However, BUV exposure from plastic sports field dust is still unknown. This study compared BUVs in plastic sports field dust and indoor dust for the first time. The order of the geometric mean concentrations of the total BUVs (ΣBUVs) in plastic sports field dust was indoor badminton courts (11023 ng g-1) > basketball courts (4777 ng g-1) > plastic tracks (3779 ng g-1) > synthetic turf (1920 ng g-1) > tennis courts (689 ng g-1). The geometric mean concentrations of ΣBUVs in indoor dust (1150 ng g-1) were lower than those in most plastic sports field dust. The dominant BUV was 2-hydroxy-4-(octyloxy)benzophenone (UV-531) in plastic sports field dust, while 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-2H-benzotriazole-2-yl)phenol] (UV-360) was the dominant BUV in indoor dust. Releases from plastic track materials, sneaker soles, and friction between them might be important BUV sources in plastic track dust. The average estimated daily intakes of ΣBUVs from plastic sports field dust for general exercisers were lower than those from indoor dust, but those for exercisers with long time or professional athletes might be higher, potentially posing health risks.

Occurrence of organic ultraviolet absorbers in the particle and gas samples from plastic greenhouses: Human inhalation intake risk assessment

The environmental pollution of organic ultraviolet absorbers (UVAs) has attracted global attention. However, the distribution, sources and risk assessment of UVAs in air from plastic greenhouses are rarely reported. This study was the first to investigate the concentrations of ten UVAs in the air samples from plastic greenhouses. The total concentrations of ten UVAs (∑10UVAs) in the air samples ranged from 5.7 × 103 ng/m3 to 6.3 × 103 ng/m3 (median 5.7 × 103 ng/m3) in greenhouses covered with biodegradable mulch film, 288.2 ng/m3 to 376.4 ng/m3 (median 333.9 ng/m3) in greenhouses covered with PE mulch film, and 97.9 ng/m3 to 142.6 ng/m3 (median 114.9 ng/m3) in greenhouses covered without mulch film. The concentrations of ten UVAs in 65 commercial agricultural films were simultaneously analyzed. Additionally, the potential health risks for greenhouse workers exposed to UVAs were estimated. And the migration simulations showed that the health risk in greenhouses may be higher even if only one UVA is added to the biodegradable mulch film. Therefore, the exposure risk of UVAs in plastic greenhouses needs to be highly prioritized.

Benzotriazole UV stabilizers disrupt epidermal growth factor receptor signaling in human cells

Phenolic benzotriazole UV stabilizers (BUV) are commonly used additives in synthetic polymeric products, which constantly leak into the environment. They are persistent and bioaccumulative, and have been detected not only in fish, birds, and sea mammals, but also in humans, including breast milk samples. Several authorities including the European Chemical Agency already consider some BUVs as Substances of Very High Concern in need of further information, e.g. mechanistical studies and biomonitoring. In this study, we are addressing this need by investigating the effect of several BUVs on the activity of the human epidermal growth factor receptor (EGFR), an important regulator of cellular processes that has recently been identified as a cell-surface receptor for environmental organic chemicals. By combining in silico docking, mutant analyses, receptor binding and internalization assays, we demonstrate that BUVs, particularly the chlorinated variants, bind to the extracellular domain of EGFR and thereby prevent the binding of growth factors. Accordingly, BUVs can inhibit EGFR downstream events, such as ERK1/2 phosphorylation and DNA synthesis, in human keratinocytes. Our data establish EGFR as a plasma membrane receptor for BUVs, offering novel mechanistic insights into the biological effects induced by these widespread and persistent chemicals. The findings of this study may not only improve hazard assessment for BUVs, but also contribute to the development of novel EGFR-targeting drugs.

A dose-dependent effect of UV-328 on photosynthesis: Exploring light harvesting and UV-B sensing mechanisms

Benzotriazole ultraviolet (UV) stabilizers (BUVs) have emerged as significant environmental contaminants, frequently detected in various ecosystems. While the toxicity of BUVs to aquatic organisms is well-documented, studies on their impact on plant life are scarce. Plants are crucial as they provide the primary source of energy and organic matter in ecosystems through photosynthesis. This study investigated the effects of UV-328 (2-(2-hydroxy-4',6'-di-tert-amylphenyl) benzotriazole) on plant growth indices and photosynthesis processes, employing conventional physiological experiments, RNA sequencing (RNA-seq) analysis, and computational methods. Results demonstrated a biphasic response in plant biomass and the maximum quantum yield of PS II (Fv/Fm), showing improvement at a 50 μM UV-328 treatment but reduction under 150 μM UV-328 exposure. Additionally, disruption in thylakoid morphology was observed at the higher concentration. RNA-seq and qRT-PCR analysis identified key differentially expressed genes (light-harvesting chlorophyll-protein complex Ⅰ subunit A4, light-harvesting chlorophyll b-binding protein 3, UVR8, and curvature thylakoid 1 A) related to photosynthetic light harvesting, UV-B sensing, and chloroplast structure pathways, suggesting they may contribute to the observed alterations in photosynthesis activity induced by UV-328 exposure. Molecular docking analyses further supported the binding affinity between these proteins and UV-328. Overall, this study provided comprehensive physiological and molecular insights, contributing valuable information to the evaluation of the potential risks posed by UV-328 to critical plant physiological processes.

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.

Insights into the effect of benzotriazoles in liver using integrated metabolomic and transcriptomic analysis

Benzotriazoles (BTRs) are a class of benzoheterocyclic chemicals that are frequently used as metal-corrosive inhibitors, both in industry and daily use. However, the exposure effect information on BTRs remains relatively limited. In this study, an integrated metabolomic and transcriptomic approach was utilized to evaluate the effect of three BTRs, benzotriazole, 6-chloro-1-hydroxi-benzotriazole, and 1-hydroxy-benzotriazole, in the mouse liver with results showing disrupted basal metabolic processes and vitamin and cofactor metabolism after 28 days. The expression of several genes that are related to the inflammatory response and aryl hydrocarbon receptor pathways, such as Gstt2 and Arntl, was altered by the exposure to BTRs. Exposure to BTRs also affected metabolites and genes that are involved in the immune system and xenobiotic responses. The altered expression of several cytochrome P450 family genes reveal a potential detoxification mechanism in the mouse liver. Taken together, our findings provide new insights into the multilayer response of the mouse liver to BTRs exposure as well as a resource for further exploration of the molecular mechanisms by which the response occurs.

Comparative evaluation of soil accumulation of light stabilizers from biodegradable mulching films versus conventional polyethylene ones

Light stabilizers are commonly used as additives in mulching films and have environmental persistence, bioaccumulation and ecotoxicity. However, their occurrence and distribution in mulching films and accumulation in mulched soils are seldom reported. This study firstly presents a comprehensive screening of 19 light stabilizers in 65 mulching films and 30 farmland soils collected in China, of which five and eight light stabilizers were 100% detected, respectively. The light stabilizer concentration in biodegradable mulching films was significantly higher than that in polyethylene ones, with median concentrations of 1.75 × 106 μg/kg and 4.86 × 103 μg/kg, respectively. Furthermore, a positive correlation was observed between the light stabilizer concentration in mulching films and in soils. This indicates that mulching films play a critical role in the accumulation of light stabilizers in farmland soils, and biodegradable mulching films significantly increase benzotriazole light stabilizers in soils. Although the light stabilizer concentration in farmland soil is relatively low, the sustainable quantities of mulching film input and the long-term accumulation will still pose a threat to the ecological environment and organism health. Consequently, our work reveals the occurrence and environmental risk of light stabilizers in mulching films and farmland soils and brings attention to light stabilizers in the soil environment.

Comparison of benzotriazole ultraviolet stabilizers (BUVs) removal from wastewater after subsequent stages of sequencing batch reactor (SBR) treatment process

The research focused on benzotriazole ultraviolet stabilizers (BUVs) which are commonly used compounds despite being found dangerous, e.g. promoting breast cancer cell proliferation, damaging vital organs such as hearts, brains livers and kidneys. The aim of the study was to analyse the efficiency and removal rate of BUVs from wastewater depending on the quantity of tested compounds and SBR anaerobic-aerobic conditions. The study was conducted in sequencing batch reactors (SBRs - 17 L) with real flocculent activated sludge (8 L) and model wastewater (5 L) containing UV-326, UV-327, UV-328, UV-329 and UV-P from 50 to 600 μg∙L-1. The SBR were operated in 390 cycles of 7 h and 10 min over 130 days. The similarity of the technological parameters of the treatment process to those used in a real wastewater treatment plant was maintained. Efficiency removal of individual BUVs was strictly dependent on the dose of compounds introduced into wastewater and ranged from 68.2 to 97 %. Removal of UV-329 occurred with lowest efficiency (from 68.2 to 85.2 %) while UV-326 was most efficiently removed from the wastewater (from 94.1 to 97 %). UV-329 was removed from wastewater with the lowest (0.0968-0.9524 μg∙L-1∙min-1) average removal rate while UV-327 with the highest (0.16-1.3357 μg∙L-1∙min-1), irrespective of BUVs dose in the influent. Secondary release of BUVs into the wastewater occurred in SBR during the settling phase and was dependent on the type and concentration of the BUVs in the raw wastewater. This occurrence was noted for UV-326 ≥ 100; UV-327 = 600; UV-328 ≥ 200; UV-329 ≥ 50 and UV-P ≥ 100 μg∙L-1. The settling phase needs to be shortened to the required minimum. This is an important conclusion for WWTPs in regards to SBR cycle duration and technological parameters of the treatment process.

Embryonic Exposure to the Benzotriazole Ultraviolet Stabilizer 2-(2H-benzotriazol-2-yl)-4-methylphenol Decreases Fertility of Adult Zebrafish (Danio rerio)

Benzotriazole ultraviolet stabilizers (BUVSs) are emerging contaminants of concern. They are added to a variety of products, including building materials, personal care products, paints, and plastics, to prevent degradation caused by ultraviolet (UV) light. Despite widespread occurrence in aquatic environments, little is known regarding the effects of BUVSs on aquatic organisms. The aim of the present study was to characterize the effects of exposure to 2-(2H-benzotriazol-2-yl)-4-methylphenol (UV-P) on the reproductive success of zebrafish (Danio rerio) following embryonic exposure. Embryos were exposed, by use of microinjection, to UV-P at <1.5 (control), 2.77, and 24.25 ng/g egg, and reared until sexual maturity, when reproductive performance was assessed, following which molecular and biochemical endpoints were analyzed. Exposure to UV-P did not have a significant effect on fecundity. However, there was a significant effect on fertilization success. Using UV-P-exposed males and females, fertility was decreased by 8.75% in the low treatment group and by 15.02% in the high treatment group relative to control. In a reproduction assay with UV-P-exposed males and control females, fertility was decreased by 11.47% in the high treatment group relative to the control. Embryonic exposure to UV-P might have perturbed male sex steroid synthesis as indicated by small changes in blood plasma concentrations of 17β-estradiol and 11-ketotestosterone, and small statistically nonsignificant decreases in mRNA abundances of cyp19a1a, cyp11c1, and hsd17b3. In addition, decreased transcript abundances of genes involved in spermatogenesis, such as nanos2 and dazl, were observed. Decreases in later stages of sperm development were observed, suggesting that embryonic exposure to UV-P impaired spematogenesis, resulting in decreased sperm quantity. The present study is the first to demonstrate latent effects of BUVSs, specifically on fish reproduction. Environ Toxicol Chem 2024;43:385-397. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Impact of plastic-related compounds on the gene expression signature of HepG2 cells transfected with CYP3A4

The presence of plastic and microplastic within the oceans as well as in marine flora and fauna have caused a multitude of problems that have been the topic of numerous investigations for many years. However, their impact on human health remains largely unknown. Such plastic and microplastic particles have been detected in blood and placenta, underlining their ability to enter the human body. Plastics also contain other compounds, such as plasticizers, antioxidants, or dyes, whose impact on human health is currently being studied. Critical enzymes within the metabolism of endogenous molecules, especially of xenobiotics, are the cytochrome P450 monooxygenases (CYPs). Although their importance in maintaining cellular balance has been confirmed, their interactions with plastics and related products are poorly understood. In this study, the possible relationship between different plastic-related compounds and CYP3A4 as one of the most important CYPs was analyzed using hepatic cells overexpressing this enzyme. Beginning with virtual compound screening and molecular docking of more than 1000 plastic-related compounds, several candidates were identified to interact with CYP3A4. In a second step, RNA-sequencing was used to study in detail the transcriptome-wide gene expression levels affected by the selected compounds. Three candidate molecules ((2,2'-methylenebis(6-tert-butyl-4-methylphenol), 1,1-bis(3,5-di-tert-butyl-2-hydroxyphenyl)ethane, and 2,2'-methylenebis(6-cyclohexyl-4-methylphenol)) had an excellent binding affinity to CYP3A4 in-silico as well as cytotoxic effects and interactions with several metabolic pathways in-vitro. We identified common pathways influenced by all three selected plastic-related compounds. In particular, the suppression of pathways related to mitosis and 'DNA-templated DNA replication' which were confirmed by cell cycle analysis and single-cell gel electrophoresis. Furthermore, several mis-regulated metabolic and inflammation-related pathways were identified, suggesting the induction of hepatotoxicity at different levels. These findings imply that these compounds may cause liver problems subsequently affecting the entire organism.

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.

Organic UV absorbents in the deepwater redfish (Sebastes mentella) from the St. Lawrence Estuary and Gulf: Distribution and human health risk assessment

UV absorbents (UVAs), such as organic UV filters (UVFs) and benzotriazole UV stabilizers (BZT-UVs), are used in a wide range of consumer and industrial products and they are contaminants of emerging concern in the environment. However, their occurrence and fate in the deep-sea environments are inadequately understood. This study investigated the occurrence and distribution of five UVFs and ten BZT-UVs in the muscle (n = 127) of 2019-collected deepwater redfish (Sebastes mentella) from the St. Lawrence Estuary and Gulf (SLEG) (Canada) to better understand the accumulation of these contaminants in deep-sea fish. Small redfish (<30 cm) tended to have higher concentrations of UVAs in the muscle than that of larger specimens (>30 cm). The UVF 2-hydroxy-4-methoxybenzophenone (BP3) was the most frequently detected (present in 34 % of all samples) target UVA, with concentrations as high as 413 ng/g (dry weight). According to the δ15N and δ13C data, pelagic-eating redfish, and individuals with lower trophic levels had higher lipid content and accumulated more BP3 in their muscles. Four BZT-UVs were detected in redfish muscle, but the detection frequency was lower than 30 %. The estimated hazard quotient for these contaminants was <2.3 × 10-2 for general Canadian populations, indicating that they are unlikely to pose health risks to humans through redfish consumption. Factors influencing UVAs bioaccumulation in redfish, as well as the effects UVAs may have on deep-sea species, should be researched further.

Physiological impact of personal care product constituents on non-target aquatic organisms

Personal care products (PCPs) are products used in cleaning, beautification, grooming, and personal hygiene. The rise in diversity, usage, and availability of PCPs has resulted in their higher accumulation in the environment. Thus, these constitute an emerging category of environmental contaminants due to the potential of its constituents (chemical and non-chemical) to induce various physiological effects even at lower concentrations (ng/L). For analyzing the impact of the PCPs constituents on the non-target organism about 300 article including research articles, review articles and guidelines were studied from 2000 to 2023. This review aims to firstly discuss the fate and accumulation of PCPs in the aquatic environment and organisms; secondly provides overview of environmental risks that are linked to PCPs; thirdly review the trends, current status of regulations and risks associated with PCPs and finally discuss the knowledge gaps and future perspectives for future research. The article discusses important constituents of PCPs such as antimicrobials, cleansing agents and disinfectants, fragrances, insect repellent, moisturizers, plasticizers, preservatives, surfactants, UV filters, and UV stabilizers. Each of them has been found to display certain toxic impact on the aquatic organisms especially the plasticizers and UV filters. These continuously and persistently release biologically active and inactive components which interferes with the physiological system of the non-target organism such as fish, corals, shrimps, bivalves, algae, etc. With a rise in the number of toxicity reports, concerns are being raised over the potential impacts of these contaminant on aquatic organism and humans. The rate of adoption of nanotechnology in PCPs is greater than the evaluation of the safety risk associated with the nano-additives. Hence, this review article presents the current state of knowledge on PCPs in aquatic ecosystems.

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.

Distribution properties of ultraviolet absorbents in different species of biodegradable plastics

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

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.

A possible but unrecognized risk of acceptable daily intake dose triazole pesticides exposure-bile acid disturbance induced pharmacokinetic changes of oral medication

Triazole antifungal pesticides work by inhibiting the activity of lanosterol-14-α-demethylase, a member of cytochrome P450 enzymes (CYPs), but this effect is non-specific. Bile acids (BAs) are important physical surfactants for lipids absorption in intestine, and synthesized by CYPs 7A1/27A1. Thus, we presume that triazole exposure might influence the therapeutic effect or safety of oral medication through disturbing the BAs pool, even though the exposure is under an acceptable daily intake (ADI) dose. Short- and long-term of ADI dose tebuconazole (TEB) exposure animal models were established through various routes, and statins with different hydrophilic and lipophilic properties were gavaged. It exhibited that the activity of CYP7A1/27A1 was indeed inhibited but the expression was up-regulated, the BAs pool was changed either the content and the composition, and the absorption behavior of statins with strong and medium degree of lipid-solubility were significantly changed. A series of experiments performed on models of intestinal mucus, Caco-2 cell monolayer and Caco-2/HT29 co-culture system revealed that the TEB-exposure induced BAs disturbance made impacts on drug absorption in many aspects, including drug solubility and the structure of intestinal barriers. This study suggests us to be more alert about the hazard of pesticides residues for elderly and chronically ill groups.

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.

Prenatal exposure to benzotriazoles and benzothiazoles and child neurodevelopment: A longitudinal study

Benzotriazoles (BTRs) and benzothiazoles (BTHs) are emerging benzo-heterocyclic compounds that may induce neurotoxicity. However, the effect of prenatal exposure to BTs (BTRs and BTHs) on child neurodevelopment has not been elucidated. We aimed to explore the associations between maternal urinary concentrations of BTs in single or in mixture with child neurodevelopment at the age of two. This study recruited 513 mother-child pairs based on a birth cohort from 2014 to 2015 in Wuhan. Maternal urinary concentrations of eight BTs (four BTRs and four BTHs) in the first, second, and third trimesters were measured. The mental development index (MDI) and psychomotor development index (PDI) of children, as two indexes of neurodevelopment, were assessed at two years old by the Bayley Scales. In the analyses of single BTs, prenatal average tolyltriazole (TTR) exposure level was associated with decreased boys' MDI scores (β = -2.84, 95 % CI: -5.11, -0.57) and prenatal average 1-H-benzotriazole (1-H-BTR) exposure level was associated with decreased boys' PDI scores (β = -1.44, 95 % CI: -2.70, -0.17), respectively. Maternal urinary concentrations of benzothiazole (BTH) in the 1^st trimester (β = -1.79, 95 % CI: -2.78, -0.80), 2^nd trimester (β = -1.14, 95 % CI: -2.19, -0.09), and the prenatal average exposure (β = -2.15, 95 % CI: -3.69, -0.61) were also negatively associated with boys' PDI scores. However, no significantly negative association was observed among girls. In the further mixture analysis, the quantile g-computation model found a significant negative association between prenatal average concentrations of BTs in mixture and boys' PDI scores [β = -4.80 (95 % CI: -9.08, -0.52)], and BTH weighted the highest in the negative association. As far as we know, this is the first research to estimate the effect of prenatal exposure to BTs on child neurodevelopment. The findings showed that prenatal exposure to BTs was negatively associated with neurodevelopment among boys, suggesting that the associations may be modified by infant sex.

Mulch film: An overlooked diffuse source of organic ultraviolet absorbers in agricultural soil

Ultraviolet absorbers (UVAs) are emerging pollutants of concern owing to their environmental persistence and endocrine-disrupting effects. UVAs are added to agricultural films to prevent UV-induced degradation, potentially leading to the release of UVAs into the soil. In this study, the occurrence of four frequently used UVAs (UV-324, UV-326, UV-328, and UV-531) in film-mulched agricultural soils (using conventional polyethylene films and biodegradable films) was investigated. Results showed that the UVA concentrations were several orders of magnitude higher in film-mulched soil (mean 91.4 μg/kg) than in unmulched soil (mean 0.08 μg/kg), indicating that mulch films are important sources of UVAs released into agricultural soil. Notably, the mean UVA concentration was up to 10 times higher in biodegradable-film-mulched soils than in polyethylene (PE) film-mulched soils; this result is consistent with our finding that the mean UVA concentration was 448 times higher in commercial biodegradable films than in PE films. In simulated migration experiments, UVAs migrated more readily into the soil from the biodegradable film than from the PE film. To our knowledge, this is the first report demonstrating that the use of mulch films may cause the accumulation of UVAs in agricultural soils as non-point sources. In particular, biodegradable plastic mulches can release more UVAs into soils.

Insights into the toxicities of UV-328, UV-329, UV-P in HepG2 cells and their roles in AHR-mediated pathway

The widespread high concentrations of benzotriazole ultraviolet stabilizers (BUVSs) in many biotic and abiotic samples have raised urgent concerns of their adverse effects on environmental and human health. In this study, we investigated the toxicity of three typical BUVSs (UV-328, UV-329, UV-P) with HepG2 cells in vitro. Results indicated that the three BUVSs showed weak cytotoxicity in HepG2 cells at concentrations lower than 50 μM. Transcriptional analysis indicated that the toxic effects of the three chemicals followed the order of UV-P > UV-329 > UV-328. UV-P and UV-329 may act as potential environmental diabetogens by significantly enriching several diabetic related items in both GO and KEGG analysis. Moreover, UV-P and UV-329 significantly upregulated the expression of AHR target genes (CYP1A1, CYP1A2, UGT1A1, etc.), and increased the ethoxyresorufin-O-deethylase (EROD) activity and exhibited agonistic activity toward AHR in the XRE-mediated luciferase reporter gene assay. Molecular docking assay also indicated that UV-329 and UV-P had higher binding affinities to AHR-LBD than UV-328. In brief, our findings indicated that UV-P and UV-329 were potential agonist of AHR ligand, and may exert more toxicity than UV-328 in inducing liver toxicity.

Occurrence and Temporal Trends of Benzotriazole UV Stabilizers in Mollusks (2010-2018) from the Chinese Bohai Sea Revealed by Target, Suspect, and Nontarget Screening Analysis

Benzotriazole UV stabilizers (BZT-UVs), including 2-(3,5-di-tert-amyl-2-hydroxyphenyl)benzotriazole (UV-328) that is currently under consideration for listing under the Stockholm Convention, are applied in many commodities and industrial products. However, limited information is available on the interannual variation of their environmental occurrence. In this study, an all-in-one strategy combining target, suspect, and nontarget screening analysis was established to comprehensively explore the temporal trends of BZT-UVs in mollusks collected from the Chinese Bohai Sea between 2010 and 2018. Significant residue levels of the target analytes were determined with a maximum total concentration of 6.4 × 10³ ng/g dry weight. 2-(2-Hydroxy-3-tert-butyl-5-methyl-phenyl)-5-chloro-benzotriazole (UV-326), 5-chloro-2-(3,5-di-tert-butyl-2-hydroxyphenyl)benzotriazole (UV-327), and 2-(2-hydroxy-5-methylphenyl) benzotriazole (UV-P) were the predominant analogues, and UV-328 was the most frequently detected BZT-UV with a detection frequency (DF) of 87%. Whereas five biotransformation products and six impurity-like BZT-UVs were tentatively identified, their low DFs and semi-quantified concentrations suggest that the targeted analytes were the predominant BZT-UVs in the investigated area. A gradual decrease in the total concentrations of BZT-UVs was observed, accompanied by downward trends of the abundant compounds (e.g., UV-326 and UV-P). Consequently, the relative abundance of UV-327 increased because of its consistent environmental presence. These results suggest that continuous monitoring and risk assessment of BZT-UVs other than UV-328 are of importance in China.

Screening of antimicrobials, fragrances, UV stabilizers, plasticizers and preservatives in sewage treatment plants (STPs) and their risk assessment in India

Community/industrial wastewater is the prime source of anthropogenic chemicals, its treatment is often a daunting task and unaffordable for many countries. Emerging Contaminants (ECs) have been drained into wastewater after continuous use/misuse and Conventional treatments in STPs do not remove them completely. ECs including antimicrobial agents, synthetic musks, Benzotriazole UV stabilizers (BUVSs), plasticizers, and preservatives are frequently reported in environment, and cause health effects to non-target organisms. Monitoring of ECs is important to understand their status in aquatic environment. Hence, it was aimed to monitor ECs (n = 21) from 11 STPs in Tamil Nadu, India. The detection frequency of most of these analytes was >90%. Antimicrobials ranged from 247 to 22,714 ng/L and 11-14,369 ng/L in influents and effluents, respectively. The synthetic musks were in the order of Tonalide > Galaxolide > Musk Ketone. BUVSs ranged from 4 to 1632 ng/L (influents) and < LOD to 29,853 ng/L (effluents). Concentration of phthalates in influents and effluents were < LOD - 11,311 ng/L and < LOD - 17,618 ng/L, respectively. Parabens were found in the order of Prophyl > Methyl > Ethyl > Butyl in influents and Methyl > Prophyl > Butyl > Ethyl in effluents. Mass loads of ECs through STPs were found as antimicrobials > plasticizers > fragrances > BUVSs > Preservatives. This study reveals increasing usage of ECs and inadequate treatment processes at STPs in India. Also helps to adopt suitable treatment processes to remove ECs from wastewater and to reuse the wastewater.

Concentrations, Compound Profiles, and Possible Sources of Organic UV Filters in Human Milk in China

Ultraviolet (UV) filters are of great concern due to their wide occurrence, bioaccumulation, and toxicity. Little is known about human exposure to UV filters. A total of 3467 individual human milk samples from 24 Chinese provinces were collected during 2017-2019. The concentrations of 12 UV filters in 100 pooled milk samples were determined. The total UV filter concentration was 78-846 (mean 235 ± 120) ng/g lipid weight. The highest and lowest total mean concentrations were for samples from Qinghai and Sichuan provinces, respectively. A significant positive correlation was found between UV radiation levels and UV concentrations in the samples. The dominant UV filters were 2-(2-hydroxy-5-methylphenyl) benzotriazole (UV-P) and ethylhexyl methoxycinnamate (EHMC), which contributed means of 32 and 22%, respectively, to the total concentrations. Plastic products and sunscreens were probably the sources of UV-P and EHMC in the human milk from China, respectively. The mean 2-(3,5-di-tert-amyl-2-hydroxyphenyl) benzotriazole (UV-328) concentration was 2.6 ± 2.6 ng/g lipid weight. The UV filter profiles were similar to profiles for samples from Japan, the Philippines, and Switzerland but not for samples from Korea and Vietnam. The estimated daily UV filter intake for breastfed infants was below the corresponding reference dose. This was the first large-scale study of UV filters in human milk and will help assess the risks posed.

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.

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

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

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.

Determination of benzotriazole and benzothiazole derivatives in tea beverages by deep eutectic solvent-based ultrasound-assisted liquid-phase microextraction and ultrahigh-performance liquid chromatography-high resolution mass spectrometry

Benzotriazole (BTRs) and benzothiazole (BTHs) derivatives are a group of high production volume chemicals with emerging health concern, which found in tea beverages raising potential risks for food safety and human health. The present work describes a simple method using a "green" deep eutectic solvent (DES) based-ultrasound-assisted liquid-phase microextraction (UALPME) to rapidly extract BTRs and BTHs from tea beverages, and then applying UHPLC-electrospray ionization (+)-quadrupole time-of-flight mass spectrometry for detection and quantification. To overcome the challenges related to different experimental conditions, a Factorial Multilevel Categoric Design and a Face Centered Central Composite Design were applied to screen and optimize the parameters for the DES-UALPME procedure, respectively. After optimization, the method was validated and shown to possess low limits of quantification (LOQs; 1.5-12 ng mL^-1), high precision (3-13%), and satisfactory accuracy (65-107%). The developed method was then successfully applied for the analysis of some selected BTRs and BTHs in tea beverages.

An analytical survey of benzotriazole UV stabilizers in plastic products and their endocrine-disrupting potential via human estrogen and androgen receptors

Benzotriazole UV stabilizers (BUVSs) are added to various materials to prevent damage from UV-irradiation. Recently, there has been great concern regarding the endocrine-disrupting effects of exposure to microplastic-derivative BUVSs in particular. In this study, we measured the concentrations of nine representative BUVSs in the plastic bottle caps of 10 beverages, 4 food packages, and 4 plastic shopping bags purchased from Japanese grocery stores by GC-MS analysis, and found that eight BUVSs, except for 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-2H-benzotriazole (UV-320), were detected from these plastic products. In particular, 2-(2-hydroxy-5-methylphenyl) benzotriazole (UV-P) and 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole (UV-326) were detected from all the bottle caps at concentrations in the order of ng/g. In addition, we characterized the agonistic and/or antagonistic activities against human estrogen receptors (ERα/β) and androgen receptor (AR) of 13 BUVSs. Results revealed that, among the 13 BUVSs, UV-P, 2-(5-tert-butyl-2-hydroxyphenyl) benzotriazole (UV-PS), 2-[2-hydroxy-5-[2-(methacryloyloxy)ethyl]phenyl]-2H-benzotriazole (UV-090) and 2-(2-hydroxy-5-tert-octylphenyl)-benzotriazole (UV-329) showed ERα and/or ERβ agonistic activity, with UV-P being the most potent based on these assays. On the other hand, UV-320 and 2-(3-s-butyl-5-tert-butyl-2-hydroxyphenyl) benzotriazole (UV-350) showed both ERα and ERβ antagonistic activities, and 2-(3,5-di-tert-amyl-2-hydroxylphenyl) benzotriazole (UV-328) and UV-329 acted as ERβ antagonists. In the AR assay, UV-P and 2-(3-allyl-2-hydroxy-5-methylphenyl)-2H-benzotriazole (UV-9) showed AR antagonistic activity although none of the test compounds showed AR agonistic activity. Taken together, our findings suggest that a series of BUVSs are present in our environments via plastic materials and several of these compounds possess endocrine-disrupting potential, such as ERα/β agonistic and/or antagonistic activity and AR antagonistic activity. UV-P and its structurally similar compounds, in particular, appear to be a cause for concern.

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.

Determination of benzotriazole and benzothiazole derivatives in human urine by eco-friendly deep eutectic solvent-based ultrasound-assisted liquid-liquid microextraction followed by ultrahigh performance liquid chromatography quadrupole-time-of-flight mass spectrometry

Benzotriazole (BTRs) and benzothiazole (BTHs) derivatives have been classified as high production volume pollutants of emerging concern. The present work describes a rapid and simple process using an eco-friendly deep eutectic solvent (DES) based-ultrasound-assisted liquid-liquid microextraction (DES-UALLME) technique to effectively extract five BTRs and four BTHs in human urine samples, and then applying ultrahigh-performance liquid chromatography and electrospray ionization (+)-quadrupole time-of-flight mass spectrometry (UHPLC-ESI(+)-QTOF-MS) for their detection and quantification. DESs are a group of novel "green" solvents, and their applications in sample pretreatment are appropriate for the requirements for green chemistry, environmental protection and sustainable development. Furthermore, to overcome the challenges related to different experimental conditions, multivariate experimental design approaches conducted by means of a multilevel categorical design and a Box-Behnken Design were applied to screen and optimize parameters that have significant influences on the extraction efficiency of DES-UALLME. After optimization, the method was validated and shown to possess low limits of quantitation (LOQs; 0.4 - 9 ng mL^-1), high precision (3-12%), and high accuracy (mean spiked recoveries; 80-101%). The developed method was then successfully applied for the analysis of BTRs and BTHs in human urine samples. Interestingly, 5,6-dimethyl-1H-benzotriazole (XTR) was detected in almost all of the urine samples, which correlates with its high production and widely applications in industry processes and consumer products in Taiwan. These target analytes could potentially be used as biomarkers to assess exposure of BTRs and BTHs in biomonitoring programs and studies.

2,6-Di-tert-butylphenol and its quinone metabolite trigger aberrant transcriptional responses in C57BL/6 mice liver

2,6-Di-tert-butylphenol (2,6-DTBP) is used as an antioxidant with wide commercial applications and its residues have been detected in various environmental matrices. 2,6-DTBP may enter human body via ingestion, inhalation or other exposure pathways. However, its susceptibility to biotransformation and potential of the metabolic products to trigger aberrant transcriptional responses remain unclear. Here, we investigated in vitro and in vivo biotransformation of 2,6-DTBP and characterized the RNA-Seq based transcriptional profiling of C57BL/6 mice liver after the exposure to 2,6-DTBP and its metabolites. 2,6-DTBP was metabolized into hydroxylated (2,6-DTBH) and para-quinone (2,6-DTBQ) products with residues detected in serum and liver of C57BL/6 mice. 2,6-DTBP and 2,6-DTBQ induced the aberrant transcription in C57BL/6 mice liver featured with 373-2861 differentially expressed genes (DEGs). They also up-regulated 1.09-2.92 fold mRNA expression of carcinogenesis-related genes such as Ccnd1, TGFβ1 and FOS in C57BL/6 mice liver. Our study indicated potential carcinogenic risk of 2,6-DTBP and its metabolites, beneficial to further evaluation of health risk of TBPs-related contaminants.

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.

Potential involvement of environmental triggers in protein aggregation with mercuric chloride as a model

Heavy metal based toxicity has a direct relation with the perturbation of protein structure. We have investigated the progressive unfolding of ovalbumin, in the presence of increasing concentration mercury (0-6.25 μM) using different spectroscopic techniques. Formation of amorphous aggregate has been observed at the physiological pH. Initial addition of HgCl₂ resulted in the association of monomers to oligomers that proceeded to non-fibrillar aggregates on further addition. The sigmoidal curve obtained from the Stern-Volmer plot clearly divided into three stage transition. A strong lag phase is observed indicating the time dependence for the association of competent monomers. The second stage was resolved into non-cooperative binding. These results match very well with the data from atomic force microscopy and the free energy change observed in the regions. Raman spectroscopic studies indicated toxic antiparallel β-sheets structure. Time dependent atomic force microscopy study revealed the off-pathway nature of amorphous aggregates. At molten globular state, similar quenching behaviour is observed. The atomic force microscopy images clearly indicate at pH 2.2 the initiation of fibril formation occurs at lower concentration of HgCl₂ itself. Our results revealed the conformation switch of ovalbumin upon the contact of an environmental toxin and its possible way of toxicity.

Transcriptomic, proteomic and metabolomic profiling unravel the mechanisms of hepatotoxicity pathway induced by triphenyl phosphate (TPP)

Triphenyl phosphate (TPP) has been found in various environmental media and in biota suggesting widespread human exposure. However, there is still insufficient information on the hepatotoxicity mechanisms of health risk exposed to TPP. In this study, TPP could induce human normal liver cell (L02) apoptosis, injury cell ultrastructure and elevate the levels of reactive oxygen species (ROS). The integrated multi-omic (transcriptomic, proteomic, and metabolomic) analysis was used to further investigate the mechanisms. Transcriptomic analysis revealed that TPP exposure markedly affected cell apoptosis, oncogene activation, REDOX homeostasis, DNA damage and repair. Additionally, proteomic analysis found that the related proteins associated with apoptosis, oxidative stress, metabolism and membrane structure were affected. And metabolomic analysis verified that the related metabolic pathways, such as glycolysis, citrate cycle, oxidative phosphorylation, lipid and protein metabolism, were also significantly disrupted. Based on the multi-omic results, a hypothesized network was constructed to discover the key molecular events in response to TPP and illustrate the mechanism of TPP-induced hepatotoxicity in L02 cells. Therefore, molecular responses could be elucidated at multiple biological levels, and multi-omic analysis could provide scientific tools for exploring potential mechanisms of toxicity and chemical risk assessment.

Prenatal exposure to benzotraizoles and benzothiazoles in relation to fetal and birth size: A longitudinal study

The presence of benzotriazoles and benzothiazoles (BTs) in maternal urine and amniotic fluid indicated the widespread fetal exposure to the contaminants. We investigated the associations of prenatal BTs exposure with fetal and birth size and explored the window of susceptibility. Participants consisted of 856 mother-infant pairs drawn from a prospective birth cohort between 2014 and 2015 in Wuhan, China. Prenatal BTs exposure were measured in multiple urine samples collected across three trimesters. We observed positive associations between prenatal exposure to specific BTs (e.g., 1-H-benzotriazole, 1-hydroxy-benzotriazole and 2-amino-benzothiazole) and femur length (FL) and birth length z-scores among girls. In boys, a 2-fold increase of averaged concentration of urinary benzothiazole (BTH) was associated with decrement in FL (β = -0.068, p < 0.001) and birth length (β = -0.055, p = 0.005) z-scores. Further analysis indicated that the negative associations between urinary concentrations of BTH and birth length z-score among boys were observed at exposure measurement in 25-35 gestational weeks. This study reported the associations between prenatal exposure to BTs and fetal and birth size, suggests the associations maybe in a sex-specific manner and the window of exposure may influence susceptibility. These findings require replication in future research.

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.

Identification of in vitro phase I metabolites of benzotriazole UV stabilizer UV-327 using HPLC coupled with mass spectrometry

The benzotriazole UV stabilizer (BUVS) 2-(5-chloro-benzotriazol-2-yl)-4,6-di-(tert-butyl)phenol (UV-327) is used in various plastic products to protect them against harmful UV radiation. Meanwhile, there are concerns about potential adverse health effects on humans, as residues of UV-327 and other BUVSs have already been detected in various environmental matrices. However, information on the metabolism of UV-327 is not yet available. Therefore, in vitro experiments with human liver microsomes (HLMs) were performed in order to identify phase I metabolites to be used as specific biomarkers of exposure in biomonitoring studies. The samples were analyzed by HPLC coupled with mass spectrometry (HPLC/MS). Potential metabolites, which were formed by hydroxylation and further oxidation to carboxylic acid, were tentatively identified. Special metabolite structures were suspected and custom-synthesized as reference substances for verification. In total, seven phase I metabolites, which may be suitable biomarkers for the assessment of exposure to UV-327, have been identified and quantified. The results of the present study provide initial insights into the metabolic pathway of UV-327, which is essential for further research on its human metabolism.

Elucidating mechanisms of immunotoxicity by benzotriazole ultraviolet stabilizers in zebrafish (Danio rerio): Implication of the AHR-IL17/IL22 immune pathway

Benzotriazole ultraviolet stabilizers (BUVSs) are widely used additives in industrial materials and personal care products that protect products from ultraviolet damage. Due to their high production volume and potential to bioaccumulate, BUVSs are an environmental pollutant of concern. In this study, juvenile zebrafish (Danio rerio) were exposed to 4 BUVSs (UV-234, UV-326, UV-329, and UV-P) at 10 and 100 μg/L for 28 d. BUVSs induced hepatic vacuolization and nuclei pyknosis in the liver following 100 μg/L UV-234 and UV-329 exposure. Transcriptomic analysis in the liver uncovered pathways related to inflammation that were affected by BUVSs. Based upon these data, we measured the expression levels of 9 genes involved in AHR-IL17/IL22 pathway in zebrafish larvae exposed to each BUVSs at one dose of either 10 or 100 μg/L for 6 days in a second set experiment. Transcript levels of interleukins il17a and il22 were decreased, while il6 mRNA was increased with exposure to UV-234, UV-329, and UV-P. No change to targeted transcripts was observed with UV-326 treatments. Moreover, cyp1a1 and ahr2 levels were increased in larvae treated with 100 μg/L UV-329 or UV-P. Consistent with expression data, protein abundance of IL22 was decreased by 29% with exposure to 100 μg/L UV-P. Taken together, these results demonstrate that exposure to different benzotriazole congeners may be associated with immunotoxicity in zebrafish through the AHR-IL17/IL22 pathway, and this may be associated with hepatic damage with prolonged exposures. This study provides new insight into unique pathways perturbed by specific BUVSs congeners.

Embryo/larval toxicity and transcriptional effects in zebrafish (Danio rerio) exposed to endocrine active riverbed sediments

Sediment toxicity plays a fundamental role in the health of inland fish communities; however, the assessment of the hazard potential of contaminated sediments is not a common objective in environmental diagnostics or remediation. This study examined the potential of transcriptional endpoints investigated in zebrafish (Danio rerio) exposed to riverbed sediments in ecotoxicity testing. Embryo-larval 10-day tests were conducted on sediment samples collected from five sites (one upstream and four downstream of the city of Milan) along a polluted tributary of the Po River, the Lambro River. Sediment chemistry showed a progressive downstream deterioration in river quality, so that the final sampling site showed up to eight times higher concentrations of, for example, triclosan, galaxolide, PAH, PCB, BPA, Ni, and Pb, compared with the uppermost site. The embryo/larval tests showed widespread toxicity although the middle river sections evidenced worse effects, as evidenced by delayed embryo development, hatching rate, larval survival, and growth. At the mRNA transcript level, the genes encoding biotransformation enzymes (cyp1a, gst, ugt) showed increasing upregulations after exposure to sediment from further downstream sites. The genes involved in antioxidant responses (sod, gpx) suggested that more critical conditions may be present at downstream sites, but even upstream of Milan there seemed to be some level of oxidative stress. Indirect evidences of potential apoptotic activity (bcl2/bax < 1) in turn suggested the possibility of genotoxic effects. The genes encoding for estrogen receptors (erα, erβ1, erβ2) showed exposure to (xeno)estrogens with a progressive increase after exposure to sediments from downstream sites, paralleled by a corresponding downregulation of the ar gene, likely related to antiandrogenic compounds. Multiple levels of thyroid disruption were also evident particularly in downstream zebrafish, as for thyroid growth (nkx2.1), hormone synthesis and transport (tg, ttr, d2), and signal transduction (trα, trβ). The inhibition of the igf2 gene reasonably reflected larval growth inhibitions. Although none of the sediment chemicals could singly explain fish responses, principal component analysis suggested a good correlation between gene transcripts and the overall trend of contamination. Thus, the combined impacts from known and unknown covarying chemicals were proposed as the most probable explanation of fish responses. In summary, transcriptional endpoints applied to zebrafish embryo/larval test can provide sensitive, comprehensive, and timeliness information which may greatly enable the assessment of the hazard potential of sediments to fish, complementing morphological endpoints and being potentially predictive of longer studies.

The molecular mechanism of the antagonistic activity of hydroxylated polybrominated biphenyl (OH-BB80) toward thyroid receptor β

Polybrominated biphenyls (PBBs) were widely used as additive brominated flame retardants. Their hydroxylated products (OH-PBBs) have been detected frequently in various marine mammals, causing an increased health risk. Till now, there lacks information on the potential disruption of OH-PBBs toward thyroid hormone receptor (TR) and the molecular characteristics of their interactions remain largely unknown. We herein in vitro and in silico evaluated the disrupting effect of 3,3',5,5'-tetrabromobiphenyl (BB80) and its metabolite 2,2'-dihydroxy- 3,3',5,5'-tetrabromobiphenyl (OH-BB80) toward human TR. The recombinant human TRβ two-hybrid yeast assay reveals the moderate antagonistic activity of OH-BB80 with IC₂₀ at 2 μmol/L, while BB80 shows no agonistic or antagonistic activity. OH-BB80 binds at the binding cavity of TRβ ligand binding domain (LBD) and forms one hydrogen bond with Phe272. Electrostatic interactions and hydrophobic interactions contribute much to their interactions. The binding of OH-BB80 quenches the intrinsic fluorescence of TRβ LBD at static quenching mode. Our study extends knowledge on the endocrine disrupting effect of OH-PBBs and suggests the full consideration of the biotransformation for further health risk assessment of PBBs and related structurally similar emerging contaminants.