Statewide Investigation of the Role of Pyrethroid Pesticides in Sediment Toxicity in California’s Urban Waterways

Abstract

A statewide investigation of urban creek sediment toxicity was conducted in California in recognition of increased incidences of toxicity linked to pyrethroid pesticides. The goals were to examine the spatial occurrence and magnitude of sediment toxicity in California urban creeks, and to examine the role of pyrethroids in toxic urban creek sediment samples. After a preliminary screening of 90 sites, 30 creeks were sampled in eight geographical regions. Sediment toxicity was assessed using 10 day bioassays with the resident amphipod Hyalella azteca. Bioassays were conducted at two test temperatures of 23 degrees C and at 15 degrees C to provide evidence of the cause of toxicity, and to more accurately reflect ambient environmental temperatures. Twenty-five of 30 samples were toxic when tested at 23 degrees C, and all 30 samples were toxic when tested at 15 degrees C. The magnitude of toxicity increased in samples tested at 15 degrees C suggesting the influence of pyrethroids, which are more toxic at colder temperatures. Pyrethroids were present in all sediment samples and were the only compounds detected at concentrations toxic to H. azteca. Bifenthrin was the pyrethroid of greatest toxicological concern, occurring in all 30 samples at concentrations up to 219 ng/g. Pyrethroid contamination of urban creeks was most severe in the Los Angeles, Central Valley, and San Diego regions, respectively. However, pyrethroids were also linked to urban creek aquatic toxicity in all regions sampled, including the less urbanized areas of the North Coast and Lake Tahoe.

Distribution and toxicity of current-use insecticides in sediment of a lake receiving waters from areas in transition to urbanization

“…Similar to the current study, SPs have been frequently detected in sediments from California (Amweg et al, 2006;Holmes et al, 2008;Trimble et al, 2009;You et al, 2008;Weston et al, 2004Weston et al, , 2005, Texas (Hintzen et al, 2009), and Illinois (Ding et al, 2010) in USA, as well as the PRD in China . The OPs, however, were detected at lower frequencies and concentrations in those studies.…”

“…On the other hand, the mean S 8 SPs concentration in sediment from Chaohu Lake was significantly lower than that in more urbanized areas in previous studies including the PRD in China , and Illinois (Ding et al, 2010) and California (Amweg et al, 2006;Holmes et al, 2008;Weston et al, 2005) in USA, while it was comparable to that in Texas, USA (Hintzen et al, 2009) (Fig. 3a).…”

“…It suggested that the riverine input of Zhigao River is an important source of OPs, and it was consistent to a previous finding which reported elevated concentrations of dichlorodiphenyltrichloroethane and its metabolites in water adjacent to Zhigao River and claimed Zhigao River played a key role in insecticides' transport to Chaohu Lake . Generally higher OP concentrations were detected in sediment near the lake shore, and the lowest Holmes et al, 2008;Trimble et al, 2009), Illinois (Ding et al, 2010), and Texas (Hintzen et al, 2009) in USA, the Pearl River Delta Mehler et al, 2011), and Chaohu Lake (the current study) in China.…”

“…Permethrin, esfenvalerate, and cypermethrin were the most frequently detected and the most abundant SPs in sediment from Chaohu Lake, with cypermethrin and permethrin being frequently found at elevated concentrations in the PRD . In USA, the dominated sediment-associated SPs in concentration were bifenthrin, permethrin, and esfenvalerate in Texas (Hintzen et al, 2009), bifenthrin, permethrin, and cypermethrin in California (Amweg et al, 2006;Holmes et al, 2008;Weston et al, 2004Weston et al, , 2005, and permethrin in Illinois (Ding et al, 2010). Permethrin was prevalent in all locations, however, its contribution to sediment toxicity was relatively low as it was the least toxic SP.…”

“…As a result of their extensive applications, residues of current-use insecticides have been frequently detected in sediments from both agricultural Weston et al, 2004) and urban areas (Amweg et al, 2006;Ding et al, 2010;Hintzen et al, 2009;Holmes et al, 2008;Lao et al, 2010;Li et al, 2011;Trimble et al, 2009;Weston et al, 2005). Recently, Li et al (2011) reported detection of sediment-associated current-use insecticides in urban waterways of the Pearl River Delta (PRD) in South China, and SPs were identified as one of the principal causes of sediment toxicity to benthic invertebrates .…”