Sub-sewershed Monitoring to Elucidate Down-the-Drain Pesticide Sources.

Pesticides have been reported in treated wastewater effluent at concentrations that exceed aquatic toxicity thresholds, indicating that treatment may be insufficient to adequately address potential pesticide impacts on aquatic life. Gaining a better understanding of the relative contribution from specific use patterns, transport pathways, and flow characteristics is an essential first step to informing source control measures. The results of this study are the first of their kind, reporting pesticide concentrations at sub-sewershed sites within a single sewer catchment to provide information on the relative contribution from various urban sources.

Wash-off potential of pyrethroids after use of total release fogger products.

Pyrethroids are frequently detected in urban wastewater. Even though treatment facilities remove most pyrethroids (> 90 %) in wastewater, residual concentrations can exceed thresholds that are acutely toxic to sensitive aquatic species. Total release foggers (also known as "bug bombs") are widely used by the general public for insect control.

Assessing pesticide uses with potentials for down-the-drain transport to wastewater in California.

Pesticides and degradates are ubiquitously detected in municipal wastewater influent in the United States. However, little detailed information exists on their sources. The aim of this study is to investigate California Pesticide Use Report (PUR) and sales data to identify pesticide uses with a high potential for indoor down-the-drain (DtD) transport.

An evaluation of temporal and spatial trends of pyrethroid concentrations in California surface waters.

Pyrethroid insecticides are frequently detected in urban surface waters at levels that are deleterious to sensitive aquatic species. The California Department of Pesticide Regulation (CDPR) Surface Water Protection Program collected 717 water and 191 sediment samples from 2009 to 2018 throughout California, providing a large dataset to conduct spatial and temporal trend analysis of pyrethroid concentrations. The pyrethroid bifenthrin accounted for 72% of average sample concentrations, and a strong relationship between whole water bifenthrin concentrations and the observed toxicity to the test species Hyallela azteca was established.

Fipronil washoff to municipal wastewater from dogs treated with spot-on products.

Fipronil and fipronil degradates have been reported in treated wastewater effluent at concentrations that exceed USEPA Aquatic Life Benchmarks, posing a potential risk to the surface waters to which they discharge. Fipronil is a common insecticide found in spot-on flea and tick treatment products that have the potential for down-the-drain transport and direct washoff into surface water. Volunteers currently treating their dogs with a fipronil-containing spot-on product were recruited.

An integrated vegetated ditch system reduces chlorpyrifos loading in agricultural runoff.

Agricultural runoff containing toxic concentrations of the organophosphate pesticide chlorpyrifos has led to impaired water body listings and total maximum daily load restrictions in California's central coast watersheds. Chlorpyrifos use is now tightly regulated by the Central Coast Regional Water Quality Control Board. This study evaluated treatments designed to reduce chlorpyrifos in agricultural runoff.

Monitoring Fipronil and Degradates in California Surface Waters, 2008-2013.

The phenylpyrazole insecticide fipronil has become a popular replacement pest management tool as organophosphorus insecticides have been phased out for residential use and pyrethroids have come under scrutiny as a surface water contaminant. There has been an increasing concern of offsite transport of fipronil to surrounding surface waters and a corresponding increase in potential toxicity to aquatic organisms. The California Department of Pesticide Regulation Environmental Monitoring Program has collected over 500 urban surface water samples throughout California since 2008 to determine the presence and concentrations of fipronil and five degradate products.

The Effects of the Landguard™ A900 Enzyme on the Macroinvertebrate Community in the Salinas River, California, United States of America.

Agricultural use of organophosphate pesticides are responsible for surface water toxicity in California and has led to a number of impaired water body listings under section 303(d) of the Clean Water Act. Integrated passive-treatment systems can reduce pesticide loading in row crop runoff, but they are only partially effective for the more soluble organophosphates. The Landguard™ enzyme has been effectively proven as an on-farm management practice for the removal of chlorpyrifos and diazinon in furrow runoff, but it has not been used in larger-scale treatment because of concerns regarding the potential impact on in-stream macroinvertebrates after chronic use.

Pesticide occurrence and aquatic benchmark exceedances in urban surface waters and sediments in three urban areas of California, USA, 2008-2011.

Urban pesticide use has a direct impact on surface water quality. To determine the extent of pesticide contamination, the California Department of Pesticide Regulation initiated a multi-area urban monitoring program in 2008. Water and sediment samples were collected at sites unaffected by agricultural inputs in three areas: Sacramento (SAC), San Francisco Bay (SFB), and Orange County (OC).

Removal mechanisms and fate of insecticides in constructed wetlands.

Constructed wetlands (CWs), along with other vegetative systems, are increasingly being promoted as a mitigation practice to treat non-point source runoff to reduce contaminants such as pesticides. However, studies so far have mostly focused on demonstrating contaminant removal efficiency. In this study, using two operational CWs located in the Central Valley of California, we explored the mechanisms underlying the removal of pyrethroids and chlorpyrifos from agricultural runoff water, and further evaluated the likelihood for the retained pesticides to accumulate within the CWs over time.

Zaleplon (Sonata) analysis in postmortem specimens by gas chromatography-electron capture detection.

Zaleplon (Sonata) is a sedative hypnotic prescription medication used for the short-term treatment of insomnia. Although Zaleplon was approved by the FDA in 1999, there has been limited postmortem information about the drug cited in the toxicology literature. Zaleplon was separated from postmortem biological specimens utilizing liquid-liquid extraction coupled with a solid-phase extraction technique, and detection was accomplished by a gas chromatography-electron capture detector.

Efficacy of constructed wetlands in pesticide removal from tailwaters in the Central Valley, California.

Pollutants in agricultural irrigation return flow (tailwater) constitute a significant nonpoint source of pollution in intensive agricultural regions such as the Central Valley of California. Constructed wetlands (CWs) represent a feasible mitigation option to remove pollutants including pesticides in the tailwater. In this study, we evaluated two CWs in the Central Valley for their performance in removing pyrethroid and organophosphate insecticides under field-scale production conditions.

Enantioselective degradation and chiral stability of pyrethroids in soil and sediment.

Synthetic pyrethroids contain two or three chiral centers, making them a family of chiral pesticides with a large number of stereoisomers. Recent studies showed significant differences in aquatic toxicity between enantiomers from the same diastereomers of pyrethroids. To better understand the ecotoxicological effect and fate of pyrethroid insecticides, chirality in biodegradation must also be considered.