Synthetic pyrethroids, such as bifenthrin, permethrin and cypermethrin, are a group of insecticides that are widely used in agriculture and urban areas. These pesticides accumulate in sediments where they can persist for many months to years. In addition, bifenthrin has been shown to enter waterways through urban runoff and through dust and therefore, has the capacity to travel long distances before contaminating waterbodies. In Melbourne, concentrations are particularly high in new residential areas. We provide an overview of the sources, impacts and management options for bifenthrin, using several of our case studies across Greater Melbourne.
These studies found bifenthrin to be a common contaminant in urban wetland sediments, detected at between 64-78% of sites (120 sites). There are multiple uses of bifenthrin in urban areas but their use in termite control may be the cause for their frequent detection and higher concentrations in waterways adjacent to new housing estates.
Our studies have also shown that concentrations of bifenthrin found within rivers and wetlands around Melbourne have the potential to be toxic to a range of aquatic organisms. Ecotoxicological data (survival, growth, biochemical biomarkers and behavior) for zooplankton, invertebrates and frogs from these studies will also be presented.
A particular focus will be a case study investigating the concentrations of bifenthrin in new housing estates and how these concentrations change over time in surrounding sediment ponds and receiving waterways. Bifenthrin was found to be persistent in these receiving waterways for over 5 years after urban construction has finished.
The implications of bifenthrin found within waterways will be discussed in the context of ecological health, as well as potential management interventions such as alternative chemical application practices (e.g. industry codes of practice) and sediment control guidelines.