Neonicotinoids are a group of moderately to highly water-soluble insecticides, with a broad range of applications in urban and agricultural settings. Over 400 agricultural and domestic neonicotinoid containing products are registered for use in Australia. Globally, neonicotinoids have attracted research and media attention for their adverse effects on non-target species such as honeybee populations across North America and Europe. The aquatic environment is a major sink of neonicotinoid insecticides from sources such as agricultural and runoff, and wastewater treatment plant (WWTP) effluents released into environmental waters, which may put aquatic species at increased risk of neonicotinoid exposure.
Little is known about the occurrence of neonicotinoids in Australian aquatic environments. Popular neonicotinoid insecticide Imidacloprid is occasionally included in environmental monitoring programs with few peer-reviewed studies documenting the occurrence of some neonicotinoids in Australian waters. Furthermore, lack of regulatory guidelines leaves data hard to interpret in terms of associated risk to aquatic environments.
The aim of this work was to investigate the occurrence of neonicotinoid insecticides in Australian aquatic environments by revisiting environmental monitoring campaigns with analytical methods recently developed for the full suite of seven neonicotinoids. From here, we aim to understand the associated risk of these chemicals to Australia’s aquatic environments.
Over 450 samples across 59 sites collected using both grab and passive sampling techniques from various environmental monitoring campaigns including drinking water, Great Barrier Reef pesticide monitoring, wastewater effluent and various smaller projects were quantitatively analysed for neonicotinoids.
Imidacloprid was the most frequently detected neonicotinoid in approx. 40% of samples with mean concentration of 0.33 µg/L and exceeded draft regulatory guidelines (0.11 µg/L in freshwater) in 6% of samples that were >LOD. Regulatory guidelines do not exist for other neonicotinoids. We discuss their environmental risk using a species sensitivity distribution approach.