Scientists in Queensland have taken the lead in adopting a new method to evaluate the long-term risks posed by toxic substances such as pesticides in rivers and oceans. Researchers at the University of Queensland have developed the "Time-Response Surface" (TRS) method, which can be applied to chemicals with cumulative or delayed toxicity, including the neonicotinoid insecticide imidacloprid widely used in agriculture. The findings have been published in the journal Environmental Science & Technology.
Cath Neelamraju, a PhD candidate at the University of Queensland's School of the Environment, said the method helps address a critical regulatory gap, better aligning environmental protection with real-world ecological risks. Neelamraju noted that existing regulatory guidelines may underestimate the ecological risks of prolonged exposure to such chemicals. Taking imidacloprid as an example, it binds to nerve receptors in aquatic insects and crustaceans, and even at low concentrations, its toxic effects intensify over time. However, current guidelines do not account for the progression of long-term toxicity, leading to an underestimation of its impact.
Previous studies have raised concerns that imidacloprid concentrations in some Queensland waterways may affect aquatic organisms, altering community structure and function. The TRS method incorporates exposure duration into ecosystem protection guidelines, providing a practical solution for long-term conservation that is consistent with established risk assessment frameworks, including Australia and New Zealand's freshwater and marine water quality guidelines and the European Water Framework Directive.
Associate Professor Ryan Turner, Director of the Reef Catchments Science Partnership, praised the University of Queensland team's work as world-leading. He believes the TRS method represents an important step toward developing more appropriate environmental guidelines for chemicals with cumulative or delayed toxicity, helping to better protect aquatic ecosystems in Australia and globally. The Dutch National Institute for Public Health and the Environment has expressed interest in exploring the method's relevance in a European context, where long-term risks from toxic substances in waterways are a key concern.
The researchers plan to further investigate how the TRS method can be applied to other toxic substances with cumulative effects, such as organophosphate pesticides, other neonicotinoids, and mercury, while also extending the approach 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 Environment, Tourism, Science and Innovation and the University of Sydney.
