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Xu X, Zhang D, Zhao K, Liu Z, Ren X, Zhang X, Lu Z, Qin C, Wang J, Wang S. Comprehensive analysis of the impact of emerging flame retardants on prostate cancer progression: The potential molecular mechanisms and immune infiltration landscape. Toxicology 2024; 501:153681. [PMID: 38006928 DOI: 10.1016/j.tox.2023.153681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 11/18/2023] [Accepted: 11/21/2023] [Indexed: 11/27/2023]
Abstract
Emerging flame retardants have been used to replace traditional flame retardants, but their potential impact on cancer, especially prostate cancer, is not well understood. Our study aimed to explore the link between flame retardants and prostate cancer, and identify potential carcinogenic mechanisms among populations exposed to emerging flame retardants. We screened flame retardant interacting genes differentially expressed in prostate cancer patients and identified hub genes by protein-protein interaction (PPI) analysis based on the STRING database. Univariate and multivariate Cox regression analyses were performed to construct risk models and identify flame retardant-related prognostic genes. We calculated the proportion of immune cell infiltration to explore the potential mechanism of the prognostic gene, and verified the target cell population of the prognostic gene in the single-cell transcriptome dataset. Our study revealed a significant link between emerging flame retardants and prostate cancer. We constructed a risk model with good predictive ability for prostate cancer prognosis using TCGA dataset, and identified six flame retardant-related prognostic genes validated in the GSE70769 dataset. We found that the expression of M2 macrophages was up-regulated in patients with high expression of prognostic genes, and the single-cell dataset confirmed the expression of prognostic genes in macrophages. Our study confirms the link between emerging flame retardants and prostate cancer, and highlights the role of immune-related pathways in the high-risk population exposed to these flame retardants.
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Affiliation(s)
- Xinchi Xu
- The State Key Lab of Reproductive, Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province 210029, China; Department of Urology, The Second People's Hospital of Wuhu, Wuhu, Anhui Province 241000, China
| | - Dong Zhang
- The State Key Lab of Reproductive, Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province 210029, China
| | - Kai Zhao
- The State Key Lab of Reproductive, Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province 210029, China
| | - Zhanpeng Liu
- The State Key Lab of Reproductive, Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province 210029, China
| | - Xiaohan Ren
- The State Key Lab of Reproductive, Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province 210029, China
| | - Xu Zhang
- The State Key Lab of Reproductive, Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province 210029, China
| | - Zhongwen Lu
- The State Key Lab of Reproductive, Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province 210029, China
| | - Chao Qin
- The State Key Lab of Reproductive, Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province 210029, China
| | - Jiawei Wang
- Department of Urology, The Second People's Hospital of Wuhu, Wuhu, Anhui Province 241000, China.
| | - Shangqian Wang
- The State Key Lab of Reproductive, Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province 210029, China.
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Guo X, Liu B, Liu H, Du X, Chen X, Wang W, Yuan S, Zhang B, Wang Y, Guo H, Zhang H. Research advances in identification procedures of endocrine disrupting chemicals. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:83113-83137. [PMID: 37347330 DOI: 10.1007/s11356-023-27755-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 05/15/2023] [Indexed: 06/23/2023]
Abstract
Endocrine disrupting chemicals (EDCs) are increasingly concerned substance endangering human health and environment. However, there is no unified standard for identifying chemicals as EDCs, which is also controversial internationally. In this review, the procedures for EDC identification in different organizations/countries were described. Importantly, three aspects to be considered in identifying chemical substances as EDCs were summarized, which were mechanistic data, animal experiments, and epidemiological information. The relationships between them were also discussed. To elaborate more clearly on these three aspects of evidence, scientific data on some chemicals including bisphenol A, 1,2-dibromo-4-(1,2 dibromoethyl) cyclohexane and perchlorate were collected and evaluated. Altogether, the above three chemicals were assessed for interfering with hormones and elaborated their health hazards from macroscopic to microscopic. This review is helpful for standardizing the identification procedure of EDCs.
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Affiliation(s)
- Xing Guo
- College of Public Health, Zhengzhou University, Zhengzhou, Henan, 450001, People's Republic of China
| | - Bing Liu
- College of Public Health, Zhengzhou University, Zhengzhou, Henan, 450001, People's Republic of China
| | - Haohao Liu
- College of Public Health, Zhengzhou University, Zhengzhou, Henan, 450001, People's Republic of China
| | - Xingde Du
- College of Public Health, Zhengzhou University, Zhengzhou, Henan, 450001, People's Republic of China
| | - Xinghai Chen
- Department of Chemistry and Biochemistry, St Mary's University, San Antonio, TX, USA
| | - Wenjun Wang
- College of Nursing, Jining Medical University, Jining, Shandong, People's Republic of China
| | - Shumeng Yuan
- College of Public Health, Zhengzhou University, Zhengzhou, Henan, 450001, People's Republic of China
| | - Bingyu Zhang
- College of Public Health, Zhengzhou University, Zhengzhou, Henan, 450001, People's Republic of China
| | - Yongshui Wang
- College of Public Health, Zhengzhou University, Zhengzhou, Henan, 450001, People's Republic of China
| | - Hongxiang Guo
- College of Life Sciences, Henan Agricultural University, Zhengzhou, Henan, 450001, People's Republic of China
| | - Huizhen Zhang
- College of Public Health, Zhengzhou University, Zhengzhou, Henan, 450001, People's Republic of China.
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Wang N, He L, Lv G, Sun X. Potential environmental fate and risk based on the hydroxyl radical-initiated transformation of atmospheric 1,2-dibromo-4-(1,2dibromoethyl)cyclohexane stereoisomers. JOURNAL OF HAZARDOUS MATERIALS 2021; 417:126031. [PMID: 34020355 DOI: 10.1016/j.jhazmat.2021.126031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 04/10/2021] [Accepted: 04/27/2021] [Indexed: 06/12/2023]
Abstract
1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), as an emerging brominated flame retardant (EBFR) pollutant, has been often observed in the air, and to comprehend its fate in the environment is still challenging due to the diversity of its stereoisomers. In this work, the environmental transformation behavior and potential toxicological implications of TBECH stereoisomers under the oxidation of OH· in the gas phase were investigated by computational chemistry. Our results indicate the complexity of the TBECH transformation reactions and the diversity of its transformation products in the atmosphere. Although the reactions of TBECH enantiomers with OH· exhibit highly consistency, it is obvious that the reactions of the four diastereoisomers of TBECH with OH· and their subsequent reactions have both specificity and similarity. The dehydrogenation intermediates produced by H-abstraction of OH· in the initial reactions may undergo oxidative debromination, hydroxylation and decomposition reactions, leading to the transformation into low bromine and monohydroxy substituted compounds, as well as debrominated or unbrominated unsaturated fatty ketones. The toxicity assessments show that all transformation products are less toxic to aquatic organisms than TBECH, but some of them are still classified at toxic or harmful levels. More importantly, some transformation products still exhibit carcinogenic and teratogenic activity. To our knowledge, this study provides, for the first time, a deep insight into the transformation mechanism, kinetics, and environmental impacts of atmospheric TBECH by theoretical calculations.
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Affiliation(s)
- Ning Wang
- Environment Research Institute, Shandong University, Qingdao 266237, China
| | - Lin He
- Atmospheric Chemistry Department (ACD), Leibniz-Institute for Tropospheric Research (TROPOS), Leipzig 04318, Germany
| | - Guochun Lv
- Environment Research Institute, Shandong University, Qingdao 266237, China
| | - Xiaomin Sun
- Environment Research Institute, Shandong University, Qingdao 266237, China.
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Marteinson SC, Bodnaryk A, Fry M, Riddell N, Letcher RJ, Marvin C, Tomy GT, Fernie KJ. A review of 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane in the environment and assessment of its persistence, bioaccumulation and toxicity. ENVIRONMENTAL RESEARCH 2021; 195:110497. [PMID: 33232751 DOI: 10.1016/j.envres.2020.110497] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 11/12/2020] [Accepted: 11/14/2020] [Indexed: 06/11/2023]
Abstract
Following the ban of many historically-used flame retardants (FRs), numerous replacement chemicals have been produced and used in products, with some being identified as environmental contaminants. One of these replacement flame retardants is 1,2-dibromo-4-(1,2-dibromoethyl)-cyclohexane (DBE-DBCH; formerly abbreviated as TBECH), which to date has not been identified for risk assessment and potential regulation. DBE-DBCH technical mixtures consist largely of α- and β-diastereomers with trace amounts of γ- and δ-DBE-DBCH. The α- and β-isomers are known contaminants in various environmental media. While current global use and production volumes of DBE-DBCH are unknown, recent studies identified that DBE-DBCH concentrations were among the highest of the measured bromine-based FRs in indoor and urban air in Europe. Yet our mass balance fugacity model and modeling of the physical-chemical properties of DBE-DBCH estimated only 1% partitioning to air with a half-life of 2.2 d atmospherically. In contrast, our modeling characterized DBE-DBCH adsorbing strongly to suspended particulates in the water column (~12%), settling onto sediment (2.5%) with minimal volatilization, but with most partitioning and adsorbing strongly to soil (~85%) with negligible volatilization and slow biodegradation. Our modeling further predicted that organisms would be exposed to DBE-DBCH through partitioning from the dissolved aquatic phase, soil, and by diet, and given its estimated logKow (5.24) and a half-life of 1.7 d in fish, DBE-DBCH is expected to bioaccumulate into lipophilic tissues. Low concentrations of DBE-DBCH are commonly measured in biota and humans, possibly because evidence suggests rapid metabolism. Yet toxicological effects are evident at low exposure concentrations: DBE-DBCH is a proven endocrine disruptor of sex and thyroid hormone pathways, with in vivo toxic effects on reproductive, metabolic, and other endpoints. The objectives of this review are to identify the current state of knowledge concerning DBE-DBCH through an evaluation of its persistence, potential for bioaccumulation, and characterization of its toxicity, while identifying areas for future research.
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Affiliation(s)
- Sarah C Marteinson
- Environment and Climate Change Canada, 867 Lakeshore Rd, Burlington, ON, L7S 1A1, Canada
| | - Anjelica Bodnaryk
- University of Manitoba, Department of Biological Sciences, Winnipeg, MB, R3T 2N2, Canada
| | - Mark Fry
- University of Manitoba, Department of Biological Sciences, Winnipeg, MB, R3T 2N2, Canada
| | - Nicole Riddell
- Wellington Laboratories, 345 Southgate Dr., Guelph, ON, N1G 3M5, Canada
| | - Robert J Letcher
- Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, 1125 Colonel By Dr., Ottawa, ON, K1S 5B6, Canada
| | - Chris Marvin
- Environment and Climate Change Canada, 867 Lakeshore Rd, Burlington, ON, L7S 1A1, Canada
| | - Gregg T Tomy
- University of Manitoba, Department of Chemistry, Winnipeg, MB, R3T 2N2, Canada
| | - Kim J Fernie
- Environment and Climate Change Canada, 867 Lakeshore Rd, Burlington, ON, L7S 1A1, Canada.
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Dong L, Wang S, Qu J, You H, Liu D. New understanding of novel brominated flame retardants (NBFRs): Neuro(endocrine) toxicity. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 208:111570. [PMID: 33396099 DOI: 10.1016/j.ecoenv.2020.111570] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 10/22/2020] [Accepted: 10/25/2020] [Indexed: 06/12/2023]
Abstract
Traditional brominated flame retardants (BFRs) negatively affect the environment and human health, especially in the sensitive (developing) nervous system. Considering the physicochemical similarities between novel brominated flame retardants (NBFRs) and BFRs, more and more evidence reveals the neurotoxic effects of NBFRs. We reviewed the neuro(endocrine) toxic effects of NBFRs in vivo and in vitro and discussed their action mechanisms based on the available information. The neurotoxic potential of NBFRs has been demonstrated through direct neurotoxicity and disruption of the neuroendocrine system, with adverse effects on neurobehavioral and reproductive development. Mechanistic studies have shown that the impact of NBFRs is related to the complex interaction of neural and endocrine signals. From disrupting the gender differentiation of the brain, altering serum thyroid/sex hormone levels, gene/protein expression, and so on, to interfere with the feedback effect between different levels of the HPG/HPT axis. In this paper, the mechanism of neurotoxic effects of NBFRs is explored from a new perspective-neuro and endocrine interactions. Gaps in the toxicity data of NBFRs in the neuroendocrine system are supplemented and provide a broader dataset for a complete risk assessment.
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Affiliation(s)
- Liying Dong
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China.
| | - Shutao Wang
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China.
| | - Jinze Qu
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China.
| | - Hong You
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China; School of Marine Science and Technology, Harbin Institute of Technology at Weihai, Weihai 264209, China.
| | - Dongmei Liu
- State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China.
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Wang X, Wei L, Wang Y, He B, Kong B, Zhu J, Jin Y, Fu Z. Evaluation of development, locomotor behavior, oxidative stress, immune responses and apoptosis in developing zebrafish (Danio rerio) exposed to TBECH (tetrabromoethylcyclohexane). Comp Biochem Physiol C Toxicol Pharmacol 2019; 217:106-113. [PMID: 30528700 DOI: 10.1016/j.cbpc.2018.12.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 11/30/2018] [Accepted: 12/02/2018] [Indexed: 12/21/2022]
Abstract
Tetrabromoethylcyclohexane (TBECH), as one emerging brominated flame retardants, is ubiquitous in the environment, including water and aquatic organisms. TBECH was found to exhibit endocrine-disrupting effects in different models, whereas a survey of comprehensive toxic effects of TBECH on zebrafish is limited. In the present study, zebrafish (Danio rerio) were waterborne exposed continuously to TBECH from embryonic stage (3 h post-fertilization (hpf)) to the time when the respective parameters were evaluated. Exposure to TBECH reduced hatchability of zebrafish embryos at 72 and 96 hpf, diminished heart rate of zebrafish larvae at 48 hpf, and increased malformation in zebrafish larvae at 96 hpf. In addition, exposure to TBECH diminished free swimming distance both in the light and under a photoperiod of 10 min light/10 min dark cycles in zebrafish larvae at 6 days post-fertilization (dpf). Moreover, exposure to TBECH elevated activities of superoxide dismutase (SOD) and catalase (CAT), malondialdehyde (MDA) content, whereas it reduced glutathione (GSH) content, in zebrafish larvae at 6 dpf. Accordingly, RT-qPCR analysis demonstrated that TBECH exposure increased the mRNA levels of sod1, sod2, cat, and gpx1 in zebrafish larvae at 6 dpf. With respect to the immune aspect, the mRNA levels of pro-inflammatory genes, including il-1b, il-6, il-8, and tnfa, in larval zebrafish at 6 dpf were increased by exposure to TBECH, while pretreatment with TBECH inhibited 24 h of exposure to LPS-stimulated elevation in the mRNA levels of the abovementioned four pro-inflammatory genes in zebrafish larvae at 6 dpf. Furthermore, TBECH treatment increased caspase-3 enzyme activities and regulated apoptosis-related genes in larval zebrafish at 6 dpf. Taken together, the data obtained in this study demonstrated that TBECH caused developmental and locomotor behavioral toxicity, immunotoxicity, oxidative stress and proapoptotic effects in early life zebrafish. The present study will help to understand the comprehensive toxicity of TBECH in zebrafish.
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Affiliation(s)
- Xia Wang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Lai Wei
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Yi Wang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Bingnan He
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Baida Kong
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Jianbo Zhu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Yuanxiang Jin
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China
| | - Zhengwei Fu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou 310014, China.
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Marteinson SC, Fernie KJ. Is the current-use flame retardant, DBE-DBCH, a potential obesogen? Effects on body mass, fat content and associated behaviors in American kestrels. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2019; 169:770-777. [PMID: 30597775 DOI: 10.1016/j.ecoenv.2018.11.104] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 11/21/2018] [Accepted: 11/22/2018] [Indexed: 06/09/2023]
Abstract
The current-use brominated flame retardant, 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (DBE-DBCH), is capable of perturbing sex steroid and thyroid hormone pathways in vitro and in vivo. Chemicals with this capability may also disrupt metabolic processes and are candidate obesogens, but this potential has not yet been determined for DBE-DBCH. Our objective was to examine gross biomarkers of metabolic disruption in captive American kestrels. Birds were exposed by diet to the β isomer at the environmentally relevant dose of 0.239 ng β-DBE-DBCH/g kestrel/day, from 30 days (d) prior to pairing through until chicks hatched (82 d) (n = 30 breeding pairs) or for 28 d (n = 16 pre-breeding pairs), and were compared with vehicle-only exposed controls. Body mass was assessed throughout the breeding season at biologically relevant time points, flight and feeding behavior was measured in 5-min samples daily, and plasma triglycerides and cholesterol were assessed at d10 of brood rearing. Treated males were heavier than controls at pairing (p = 0.051), the final week of courtship (p = 0.061), and at d10 (p = 0.012) and d20 of brood rearing (p = 0.051); β-DBE-DBCH-exposed breeding females were similar in weight to control females. Treated birds tended to have higher plasma triglycerides (p = 0.078), which for females, was positively associated with body mass (p = 0.019). Heavier breeding males had higher plasma concentrations of testosterone and total thyroxine (p ≤ 0.046). Overall, both sexes exposed to β-DBE-DBCH demonstrated reduced flight behavior and increased feeding behavior during courtship. In the pre-breeding pairs, treated male and female kestrels had a higher percentage of body fat than respective controls (p = 0.045). These results demonstrate that β-DBE-DBCH elicited inappropriate fat and weight gain in adult American kestrels, consistent with their increased feeding, reduced flight activity and endocrine changes, and suggests that DBE-DBCH may be an obesogen warranting further research to test this hypothesis.
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Affiliation(s)
- Sarah C Marteinson
- Ecotoxicology & Wildlife Health Division, Science & Technology Branch, Environment and Climate Change Canada, Burlington, Ontario, Canada
| | - Kim J Fernie
- Ecotoxicology & Wildlife Health Division, Science & Technology Branch, Environment and Climate Change Canada, Burlington, Ontario, Canada.
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Marteinson SC, Palace V, Letcher RJ, Fernie KJ. Disruption of thyroxine and sex hormones by 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (DBE-DBCH) in American kestrels (Falco sparverius) and associations with reproductive and behavioral changes. ENVIRONMENTAL RESEARCH 2017; 154:389-397. [PMID: 28189029 DOI: 10.1016/j.envres.2017.01.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 12/21/2016] [Accepted: 01/05/2017] [Indexed: 06/06/2023]
Abstract
1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (DBE-DBCH - formerly TBECH) is an emerging brominated flame retardant (BFR) pollutant with androgen potentiating ability and other endocrine disrupting effects in birds and fish. The objectives of this study were to determine the effects of exposure to environmentally-relevant levels of DBE-DBCH on circulating levels of thyroid and sex steroid hormones in American kestrels, and if hormonal concentrations were related to previously reported changes in reproductive success and courtship behaviors. Sixteen kestrel pairs were exposed to 0.239ng β-DBE-DBCH/g kestrel/day by diet, based on concentrations in wild bird eggs, from 4 weeks before pairing until the chicks hatched (mean 82 d), and were compared with vehicle-only-exposed control pairs (n=15). As previously reported, DBE-DBCH concentrations were not detected in tissue or eggs of these birds, nor were any potential metabolites, despite the low method limits of detection (≤0.4ng/g wet weight), suggesting it may be rapidly metabolized and/or eliminated by the kestrels. Nevertheless, exposed kestrels demonstrated changes in reproduction and behavior, indicating an effect from exposure. During early breeding, males were sampled at multiple time points at pairing and during courtship and incubation; females were blood sampled at pairing only; both sexes were sampled at the end of the season. All comparisons are made to control males or control females, and the relative differences in hormone concentrations between treatment and control birds, calculated separately for each sex, are presented for each time point. Males exposed to β-DBE-DBCH demonstrated significantly (p=0.05) lower concentrations of total thyroxine (TT4) overall, that were 11-28% lower than those of control males at the individual sampling points, yet significantly higher (p=0.03) concentrations of free thyroxine (FT4), that were 5-13% higher than those of control males at the individual sampling points; females had similar concentrations of TT4 and FT4 at the time of pairing, and T4 was similar in both sexes at the end of the breeding season. Testosterone (T) concentrations in the treatment males were significantly higher during early (85%) and mid-courtship (30%) (time*treatment p=0.001), whereas females demonstrated a reduction in T at the time of pairing (17%, p=0.05). In the treatment females, concentrations of 17β-estradiol (E2) showed a non-significant decrease (20%) and were positively correlated with T concentrations (p=0.03); E2 concentrations were below quantification limits in males. For males, some variation in T was also significantly associated with their sexual behavior (p<0.001) and FT4 concentrations (p=0.01). For females, there was no relationship between hormones measured at pairing and subsequent sexual behaviors or reproductive measures. This study demonstrates that exposure to β-DBE-DBCH at levels that are likely below those experienced by wild birds, affects the thyroid and sex steroid axes in birds and thus may be a contaminant of concern for wildlife warranting further research.
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Affiliation(s)
- Sarah C Marteinson
- Ecotoxicology & Wildlife Health Division, Science & Technology Branch, Environment and Climate Change Canada, Burlington, Ontario, Canada
| | - Vince Palace
- International Institute for Sustainable Development - Experimental Lakes Area (IISD-ELA), 111 Lombard, Suite 325, Winnipeg, Manitoba R3B 0T4, Canada
| | - Robert J Letcher
- Ecotoxicology & Wildlife Health Division, Science & Technology Branch, Environment and Climate Change Canada, National Wildlife Research Centre, Ottawa, Ontario, Canada
| | - Kim J Fernie
- Ecotoxicology & Wildlife Health Division, Science & Technology Branch, Environment and Climate Change Canada, Burlington, Ontario, Canada.
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