Ecotoxicity of Fire Retardants to Zebrafish (<i>Danio rerio</i>) in Early Life Stages

With the escalating frequency and intensity of global wildfires driven by climate change, fire retardants (FRs) have become essential tools in wildfire management. Despite their widespread use, the environmental safety of newer FR formulations—particularly in relation to aquatic ecosystems and devel...

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Main Authors: Darlan Quinta Brito, Tathyana Benetis Piau, Carlos Henke-Oliveira, Eduardo Cyrino Oliveira-Filho, Cesar Koppe Grisolia
Format: Article
Language:English
Published: MDPI AG 2025-05-01
Series:Journal of Xenobiotics
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Online Access:https://www.mdpi.com/2039-4713/15/3/79
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author Darlan Quinta Brito
Tathyana Benetis Piau
Carlos Henke-Oliveira
Eduardo Cyrino Oliveira-Filho
Cesar Koppe Grisolia
author_facet Darlan Quinta Brito
Tathyana Benetis Piau
Carlos Henke-Oliveira
Eduardo Cyrino Oliveira-Filho
Cesar Koppe Grisolia
author_sort Darlan Quinta Brito
collection DOAJ
description With the escalating frequency and intensity of global wildfires driven by climate change, fire retardants (FRs) have become essential tools in wildfire management. Despite their widespread use, the environmental safety of newer FR formulations—particularly in relation to aquatic ecosystems and developmental toxicity—remains insufficiently understood. In particular, their effects on fish embryos, which represent a sensitive and ecologically important life stage, are poorly characterized. This study investigated the acute toxicity of three commercially available FRs—N-Borate, N-Phosphate+, and N-Phosphate-—on early life stages of zebrafish (<i>Danio rerio</i>), based on an OECD 236 Fish Embryo Toxicity (FET) test. Notably, N-Phosphate- FR exhibited significant toxicity with a 96 h LC50 of 60 mg/L (0.0055%), while N-Borate (>432 mg/L, >0.032%) and N-Phosphate+ (>1181 mg/L, >0.08%) showed substantially lower toxicity. Sublethal effects, including reduced yolk sac absorption and yolk sac darkening, were observed across all FRs, highlighting potential developmental disruptions. The elevated toxicity of N-Phosphate- FR likely stems from its surfactant content. These findings reveal variations in the acute toxicity of different FR formulations, emphasizing the need for ecotoxicological assessments to guide the selection of safer FRs for wildfire management and to protect aquatic biodiversity. The results highlight the importance of incorporating developmental endpoints in FR risk assessments and provide foundational data for regulatory decisions regarding FR application near aquatic habitats. Further research is necessary to elucidate the mechanisms underlying observed effects and to evaluate cross-species toxicity at environmentally relevant concentrations.
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spelling doaj-art-0fc0b90867e440f395bd7ca674f5f2ca2025-08-20T03:16:33ZengMDPI AGJournal of Xenobiotics2039-47052039-47132025-05-011537910.3390/jox15030079Ecotoxicity of Fire Retardants to Zebrafish (<i>Danio rerio</i>) in Early Life StagesDarlan Quinta Brito0Tathyana Benetis Piau1Carlos Henke-Oliveira2Eduardo Cyrino Oliveira-Filho3Cesar Koppe Grisolia4Faculty UnB at Planaltina, University of Brasília, Planaltina 73345-010, BrazilLaboratory of Genetic Toxicology (G-Tox), Department of Genetics and Morphology, University of Brasília, Brasília 70910-900, BrazilDepartment of Ecology, Institute of Biological Sciences, University de Brasília, Brasília 70910-900, BrazilLaboratory of Ecotoxicology, Embrapa Cerrados, Planaltina 73310-970, BrazilLaboratory of Genetic Toxicology (G-Tox), Department of Genetics and Morphology, University of Brasília, Brasília 70910-900, BrazilWith the escalating frequency and intensity of global wildfires driven by climate change, fire retardants (FRs) have become essential tools in wildfire management. Despite their widespread use, the environmental safety of newer FR formulations—particularly in relation to aquatic ecosystems and developmental toxicity—remains insufficiently understood. In particular, their effects on fish embryos, which represent a sensitive and ecologically important life stage, are poorly characterized. This study investigated the acute toxicity of three commercially available FRs—N-Borate, N-Phosphate+, and N-Phosphate-—on early life stages of zebrafish (<i>Danio rerio</i>), based on an OECD 236 Fish Embryo Toxicity (FET) test. Notably, N-Phosphate- FR exhibited significant toxicity with a 96 h LC50 of 60 mg/L (0.0055%), while N-Borate (>432 mg/L, >0.032%) and N-Phosphate+ (>1181 mg/L, >0.08%) showed substantially lower toxicity. Sublethal effects, including reduced yolk sac absorption and yolk sac darkening, were observed across all FRs, highlighting potential developmental disruptions. The elevated toxicity of N-Phosphate- FR likely stems from its surfactant content. These findings reveal variations in the acute toxicity of different FR formulations, emphasizing the need for ecotoxicological assessments to guide the selection of safer FRs for wildfire management and to protect aquatic biodiversity. The results highlight the importance of incorporating developmental endpoints in FR risk assessments and provide foundational data for regulatory decisions regarding FR application near aquatic habitats. Further research is necessary to elucidate the mechanisms underlying observed effects and to evaluate cross-species toxicity at environmentally relevant concentrations.https://www.mdpi.com/2039-4713/15/3/79wildfiresfire retardants<i>Danio rerio</i>embryotoxicity
spellingShingle Darlan Quinta Brito
Tathyana Benetis Piau
Carlos Henke-Oliveira
Eduardo Cyrino Oliveira-Filho
Cesar Koppe Grisolia
Ecotoxicity of Fire Retardants to Zebrafish (<i>Danio rerio</i>) in Early Life Stages
Journal of Xenobiotics
wildfires
fire retardants
<i>Danio rerio</i>
embryotoxicity
title Ecotoxicity of Fire Retardants to Zebrafish (<i>Danio rerio</i>) in Early Life Stages
title_full Ecotoxicity of Fire Retardants to Zebrafish (<i>Danio rerio</i>) in Early Life Stages
title_fullStr Ecotoxicity of Fire Retardants to Zebrafish (<i>Danio rerio</i>) in Early Life Stages
title_full_unstemmed Ecotoxicity of Fire Retardants to Zebrafish (<i>Danio rerio</i>) in Early Life Stages
title_short Ecotoxicity of Fire Retardants to Zebrafish (<i>Danio rerio</i>) in Early Life Stages
title_sort ecotoxicity of fire retardants to zebrafish i danio rerio i in early life stages
topic wildfires
fire retardants
<i>Danio rerio</i>
embryotoxicity
url https://www.mdpi.com/2039-4713/15/3/79
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AT carloshenkeoliveira ecotoxicityoffireretardantstozebrafishidaniorerioiinearlylifestages
AT eduardocyrinooliveirafilho ecotoxicityoffireretardantstozebrafishidaniorerioiinearlylifestages
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