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Environmental impacts of polymeric flame retardant breakdown

Nature Sustainability volume 8, pages 432–445 (2025)Cite this article

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Abstract

The industrial use of monomeric halogenated flame retardants has now gradually been phased out due to their toxicity to humans and ecosystems. Polymeric flame retardants are emerging as a ‘safe’ alternative and so have a high production and consumption volume. However, the environmental fate and toxicity of their derivatives remain unknown, making it difficult to understand and adequately manage the associated risk. We take two tetrabromobisphenol A-based polymers (polyTBBPAs) that are widely used in electronics as model flame-retardant chemicals, and we study their behaviour when they break down in the environment and the toxicity of the derivative products. Our results show that polyTBBPAs break down into smaller products in the environment. Using a non-target screening strategy called BrMiner developed by us, we identified 76 breakdown products of polyTBBPAs with molecular weights in the range 400–2,000 Da. These were detected in environmental samples taken from electronic waste recycling facilities in South China. Toxicity tests with zebrafish embryos showed that when they break down in the environment, polyTBBPAs become more toxic, with mitochondrial dysfunction representing a key toxicity mechanism. This study reveals that there are environmental risks associated with polymeric flame retardants, and therefore, their use should be adequately assessed and regulated.

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Fig. 1: The framework for the exploration of polyTBBPA breakdown and subsequent impact on environmental or health risks.
Fig. 2: Establishing the BrMiner strategy.
Fig. 3: Exploration of polyTBBPA breakdown products and pathways.
Fig. 4: Environmental distribution of polyTBBPA breakdown products.
Fig. 5: Zebrafish embryonic developmental toxicity.

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Data availability

The data supporting the findings of this study are available within the paper and its Supplementary Information. Source data are provided with this paper.

Code availability

The code for BrMiner is already open access and can be found at: https://github.com/speakinside/BrMiner. All other tools used in this study are publicly accessible commercial software.

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Acknowledgements

We acknowledge funding support from the National Key Research and Development Programme of China (Grant Nos. 2023YFC3706601 and 2022YFC3202101 to X.L. and X.Z.), the National Natural Science Foundation of China (Grant Nos. 42477236 and 22176229 to X.L. and Y.W.) and the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2024B1515020050 to X.L.). We thank Y. Yang from the Guangdong University of Technology for supporting sample collection, G. Qu from the Research Center of Eco-Environmental Sciences, Chinese Academy of Sciences, for providing synthesized standards of selected TBBPA-related chemicals, and Y. Wu from the Research Center of Analysis and Test of East China University of Science and Technology for NMR characterization of synthesized standards. We also thank L. Birnbaum and R. Fuoco, MPH, for their invaluable comments.

Author information

Author notes

  1. These authors contributed equally: Xiaotu Liu, Yinran Xiong, Xiao Gou.

Authors and Affiliations

  1. College of Environment and Climate, Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou, China

    Xiaotu Liu, Lei Zhao, Xiaoyun Fan, Yang Yu & Da Chen

  2. School of Chemistry & Molecular Engineering and Research Centre of Analysis and Test, East China University of Science and Technology, Shanghai, China

    Yinran Xiong, Yiping Du & Ting Wu

  3. State Key Laboratory of Pollution Control & Resource Reuse, School of the Environment, Nanjing University, Nanjing, China

    Xiao Gou & Xiaowei Zhang

  4. Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Sun Yat-Sen University, Guangzhou, China

    Shanquan Wang

  5. Guangdong Provincial Key Laboratory of Food, Nutrition and Health, Department of Toxicology, School of Public Health, Sun Yat-sen University, Guangzhou, China

    Yanhong Wei, Zhuyi Zhang & Shuxin Jiang

  6. Green Science Policy Institute, Berkeley, CA, USA

    Arlene Blum & Lydia Jahl

  7. Department of Earth Sciences and School of the Environment, University of Toronto, Toronto, Ontario, Canada

    Miriam L. Diamond

  8. School of Ecology and Environmental Science, Yunnan University, Kunming, China

    Xiaowei Zhang

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Contributions

D.C., T.W. and X.L. designed the research. Y.X., X.L. and Y.D. carried out the development and validation of BrMiner. X.L., L.Z. and Y.Y. analysed the environmental samples and performed the laboratory simulations. S.W. carried out microbial experiments. X.F. carried out the ball milling analysis. X.G. and X.Z. carried out the zebrafish embryo experiments. Y.W., Z.Z. and S.J. conducted the in vitro mitoROS assay. D.C., T.W., X.L., X.G. and Y.X. wrote the manuscript with input from all authors. A.B., L.J. and M.L.D. reviewed and edited the manuscript and Supplementary Information. D.C. directed and supervised the study.

Corresponding authors

Correspondence to Xiaowei Zhang, Ting Wu or Da Chen.

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The authors declare no competing interests.

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Nature Sustainability thanks Christoph Koch and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Notes 1–13, Figs. 1–42 and Tables 1–13.

Reporting Summary

Supplementary Data 1

Potential breakdown products of polyTBBPA under photolytic, microbial and physical processes identified with BrMiner.

Supplementary Data 2

Toxicity contributions of identified breakdown products in the polyTBBPA breakdown mixtures.

Supplementary Data 3

Source data for Supplementary Figs. 11–15 and 18–20.

Supplementary Data 4

Source data for Supplementary Figs. 26, 29, 31–34, 38–40 and 42.

Source data

Source Data Fig. 3

Statistical Source Data for Fig. 3.

Source Data Fig. 4

Statistical Source Data for Fig. 4.

Source Data Fig. 5

Statistical Source Data for Fig. 5.

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Liu, X., Xiong, Y., Gou, X. et al. Environmental impacts of polymeric flame retardant breakdown. Nat Sustain 8, 432–445 (2025). https://doi.org/10.1038/s41893-025-01513-z

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