Queensland scientists have pioneered a new method to assess the long-term risks posed by toxicants such as insecticides in rivers and the ocean.
The Temporal Response Surface (TRS) method developed by researchers at The University of Queensland can be applied to chemicals that exhibit cumulative or delayed toxicity, including the neonicotinoid insecticide imidacloprid which is used in agriculture.
PhD candidate Cath Neelamraju from UQ's School of the Environment said the method helps to address an important regulatory gap, ensuring environmental protections are better aligned with real-world ecological risks.
"Existing regulatory guidelines may be underestimating the ecological risks of prolonged exposure to these kinds of chemicals," Ms Neelamraju said.
"Imidacloprid binds to the neural receptors in aquatic insects and crustaceans and its toxic effects intensify over time, even at lower concentrations.
"The impact of this pesticide is being underestimated because current guidelines do not account for the progression of toxicity over extended periods."
Previous research has raised concerns that imidacloprid concentrations in some Queensland waterways have the potential to impact aquatic life, altering community structure and function.
The TRS method offers a practical solution by integrating exposure duration into ecosystem protection guidelines to better support long-term protection.
It aligns with established risk assessment frameworks, such as the Australian and New Zealand Guidelines for Fresh and Marine Water Quality and the European Water Framework Directive.
Associate Professor Ryan Turner , Director of the Reef Catchments Science Partnership said the work of the UQ team was world-leading.
"The TRS approach represents a major step toward more appropriate environmental guidelines for chemicals with cumulative or delayed toxicity, helping to better protect aquatic ecosystems both in Australia and globally," Dr Turner said.
"There is already interest from the Dutch National Institute for Public Health and the Environment to explore its relevance in a European context, where long-term risks from toxicants in waterways are a critical concern."
The researchers plan to explore how the TRS method can be applied to other toxicants with cumulative effects, including organophosphorus insecticides, other neonicotinoids, and mercury.
The method may also be expanded to account for additional environmental stressors such as pH fluctuations and temperature changes.
The method was developed in collaboration with researchers from the Queensland Government Department of the Environment, Tourism, Science and Innovation and the University of Sydney.
The research is published in Environmental Science & Technology.
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