Predicted transport of pyrethroid insecticides from an urban landscape to surface water

Abstract

We developed a simple screening-level model of exposure of aquatic species to pyrethroid insecticides for the lower American River watershed (California, USA). The model incorporated both empirically derived washoff functions based on existing, small-scale precipitation simulations and empirical data on pyrethroid insecticide use and watershed properties for Sacramento County, California. We calibrated the model to in-stream monitoring data and used it to predict daily river pyrethroid concentration from 1995 through 2010. The model predicted a marked increase in pyrethroid toxic units starting in 2000, coincident with an observed watershed-wide increase in pyrethroid use. After 2000, approximately 70% of the predicted total toxic unit exposure in the watershed was associated with the pyrethroids bifenthrin and cyfluthrin. Pyrethroid applications for above-ground structural pest control on the basis of suspension concentrate product formulations accounted for greater than 97% of the predicted total toxic unit exposure. Projected application of mitigation strategies, such as curtailment of structural perimeter band and barrier treatments as recently adopted by the California Department of Pesticide Regulation, reduced predicted total toxic unit exposure by 84%. The model also predicted that similar reductions in surface water concentrations of pyrethroids could be achieved through a switch from suspension concentrate categorized products to emulsifiable concentrate categorized products without restrictions on current use practice. Even with these mitigation actions, the predicted concentration of some pyrethroids would continue to exceed chronic aquatic life criteria.

Development and application of the adverse outcome pathway framework for understanding and predicting chronic toxicity: II. A focus on growth impairment in fish

“…Pyrethroids are widely used neurotoxic insecticides frequently found in aquatic systems worldwide (Jorgenson et al, 2013) and shown to persist in sediments (Amweg et al, 2005;Weston et al, 2013). Pyrethroids are highly toxic to non-target organisms, including aquatic invertebrates and fish (Werner and Moran, 2008).…”

Concentrations and loads of PCBs, dioxins, PAHs, PBDEs, OC pesticides and pyrethroids during storm and low flow conditions in a small urban semi-arid watershed

“…In the few studies to date, concentrations have commonly been detected in direct correlation with the local use patterns of agricultural and urban insecticides (Weston et al, 2009;Hladik and Kuivila, 2009;Weston and Lydy, 2010;Jorgenson et al, 2013). Estimates of loads and yields from watersheds are rare and relationships between differing land use patterns and individual pyrethroids are likely complex and confounded by the somewhat random availability of products and applicator trends at the local scale.…”

Mixture Toxicity of Imidacloprid and Cyfluthrin to Two Non-target Species, the Fathead Minnow Pimephales promelas and the Amphipod Hyalella azteca

“…This increase in toxicity from the mixture further emphasizes the importance of testing mixtures especially because cyfluthrin and imidacloprid are found together in household insecticides, and it is likely that chemical mixtures leach into waterways and affect nontarget aquatic species (Jorgenson et al 2013). Furthermore, mixture testing is important to conduct for estimations of toxicity because organisms are seldom exposed to a single chemical stressor.…”

“…Several household and turf pesticides are available to consumers that include pyrethroid-neonicotinoid mixtures (Larson et al 2014); therefore, it is important to examine the effects of the two insecticides to nontarget species due to potential for the pesticide mixture to travel off-site into nearby urban streams (Jorgenson et al 2013). Several studies examined effects to nontarget species from cyfluthrin and imidacloprid individually, but none have evaluated the mixture.…”