2021 RMP Water Cruise Plan

San Francisco Estuary Institute (SFEI) | October 14th, 2021

This report details plans associated with the annual Regional Monitoring Program for Water Quality in the San Francisco Estuary (RMP) water cruise. The RMP water samplin

This report details plans associated with the annual Regional Monitoring Program for Water Quality in the San Francisco Estuary (RMP) water cruise. The RMP water sampling program was redesigned in 2002 to adopt a randomized sampling design at thirty-one sites in place of the twenty-six base program stations sampled previously. In 2007, the number of sites was decreased to twenty-two stations, and it remains as such for 2021. The analytes for 2021 have been modified based on the Status and Trends (S&T) Review process that started in 2020. The analytes that are being removed from the program include selenium and methylmercury (dissolved and particulate), while bisphenols and organophosphate esters (OPEs) have been added to S&T monitoring.

A multi-scale approach for identification of potential pesticide use sites impacting vernal pool critical habitat in California

Science of the Total Environment (Elsevier) | October 17th, 2022

Spatially explicit ecological risk assessment (ERA) requires estimating the overlap between chemical and receptor distribution to evaluate the potential impacts of exposu

Spatially explicit ecological risk assessment (ERA) requires estimating the overlap between chemical and receptor distribution to evaluate the potential impacts of exposure on nontarget organisms. Pesticide use estimation at field level is prone to error due to inconsistencies between ground-reporting and geospatial data coverage; attempts to rectify these inconsistencies have been limited in approach and rarely scaled to multiple crop types. We built upon a previously developed Bayesian approach to combine multiple crop types for a probabilistic determination of field-crop assignments and to examine co-occurrence of critical vernal pool habitats and bifenthrin application within a 5-county area in California (Madera, Merced, Sacramento, San Joaquin, and Stanislaus counties). We incorporated a multi-scale repeated sampling approach with an area constraint to improve the delineation of field boundaries and better capture variability in crop assignments and rotation schemes. After comparing the accuracy of the spatial probabilistic approach to USDA Census of Agriculture crop acreage data, we found our approach allows more specificity in the combination of crop types represented by the potential application area and improves acreage estimates when compared to traditional deterministic approaches. In addition, our multi-scale sampling scheme improved estimates of bifenthrin acreage variability for co-occurrence analysis and allowed for estimates of crop rotations that were previously uncaptured. Our approach could be leveraged for more realistic, spatially resolved exposure and effects models both in and outside of California.

A pesticide and iPSC dopaminergic neuron screen identifies and classifies Parkinson-relevant pesticides

Nature Portfolio (Springer Nature) | May 16th, 2023

Parkinson’s disease (PD) is a complex neurodegenerative disease with etiology rooted in genetic vulnerability and environmental factors. Here we combine quantitative ep

Parkinson’s disease (PD) is a complex neurodegenerative disease with etiology rooted in genetic vulnerability and environmental factors. Here we combine quantitative epidemiologic study of pesticide exposures and PD with toxicity screening in dopaminergic neurons derived from PD patient induced pluripotent stem cells (iPSCs) to identify Parkinson’s-relevant pesticides. Agricultural records enable investigation of 288 specific pesticides and PD risk in a comprehensive, pesticide-wide association study. We associate long-term exposure to 53 pesticides with PD and identify co-exposure profiles. We then employ a live-cell imaging screening paradigm exposing dopaminergic neurons to 39 PD-associated pesticides. We find that 10 pesticides are directly toxic to these neurons. Further, we analyze pesticides typically used in combinations in cotton farming, demonstrating that co-exposures result in greater toxicity than any single pesticide. We find trifluralin is a driver of toxicity to dopaminergic neurons and leads to mitochondrial dysfunction. Our paradigm may prove useful to mechanistically dissect pesticide exposures implicated in PD risk and guide agricultural policy.

Agrichemicals in surface water and birth defects in the United States

Acta Paediatrica (Wiley) | March 6th, 2009

Objectives: To investigate if live births conceived in months when surface water agrichemicals are highest are at greater risk for birth defects. Methods: Monthly conc

Objectives: To investigate if live births conceived in months when surface water agrichemicals are highest are at greater risk for birth defects. Methods: Monthly concentrations during 1996–2002 of nitrates, atrazine and other pesticides were calculated using United States Geological Survey's National Water Quality Assessment data. Monthly United States birth defect rates were calculated for live births from 1996 to 2002 using United States Centers for Disease Control and Prevention natality data sets. Birth defect rates by month of last menstrual period (LMP) were then compared to pesticide/nitrate means using logistical regression models. Results: Mean concentrations of agrichemicals were highest in April–July. Total birth defects, and eleven of 22 birth defect subcategories, were more likely to occur in live births with LMPs between April and July. A significant association was found between the season of elevated agrichemicals and birth defects. Conclusion: Elevated concentrations of agrichemicals in surface water in April–July coincided with higher risk of birth defects in live births with LMPs April–July. While a causal link between agrichemicals and birth defects cannot be proven from this study an association might provide clues to common factors shared by both variables.

Assessing the presence of current-use pesticides in mid-elevation Sierra Nevada streams using passive samplers, California, 2018–19

U.S. Geological Survey (USGS) | February 9th, 2023

Passive sampler devices were deployed in six northern California streams five times between November 2018 and December 2019 to measure the presence or absence of current-

Passive sampler devices were deployed in six northern California streams five times between November 2018 and December 2019 to measure the presence or absence of current-use pesticides in surface water. In the targeted areas, there are reported pesticide uses for agriculture, commercial forestry, and rights of way maintenance along with unreported pesticide use at private residences and cannabis grow sites. The sites sampled in this study were not previously monitored for current-use pesticides. Streams in the Sierra Nevada foothills of northern California are important habitats for many sensitive species including salmonids, but the logistics of sampling these areas can be difficult using traditional water-quality sampling techniques, especially when sampling watersheds where contaminant transport is episodic. Chemcatcher passive sampling devices and silicone bands were deployed in these areas to concentrate pesticides for days to weeks at a time. The U.S. Geological Survey, in cooperation with the Central Valley Regional Water Quality Control Board, was responsible for developing passive sampler field deployment and laboratory analytical methods for current-use pesticides, providing pesticide measurements from streams in the study region, and determining how well passive samplers detect pesticides in these environments. Six sites were monitored during the study, and passive sampler extracts were analyzed for a total 155 current-use pesticides in this study. A total of 19 out of the 155 pesticides including 9 insecticides, 5 fungicides, and 5 herbicides were detected in extracts from passive samplers. The most frequently detected pesticides were the herbicides hexazinone and dithiopyr, the insecticides bifenthrin and methoxyfenozide, and the fungicide azoxystrobin.

Assessment of Interim Flow Water-Quality Data of the San Joaquin River Restoration Program and Implications for Fishes, California, 2009–11

U.S. Geological Survey (USGS) | June 29th, 2015

After more than 50 years of extensive water diversion for urban and agriculture use, a major settlement was reached among the U.S. Departments of the Interior and Commerc

After more than 50 years of extensive water diversion for urban and agriculture use, a major settlement was reached among the U.S. Departments of the Interior and Commerce, the Natural Resources Defense Council, and the Friant Water Users Authority in an effort to restore the San Joaquin River. The settlement received Federal court approval in October 2006 and established the San Joaquin River Restoration Program, a multi-agency collaboration between State and Federal agencies to restore and maintain fish populations, including Chinook salmon, in the main stem of the river between Friant Dam and the confluence with the Merced River. This is to be done while avoiding or minimizing adverse water supply effects to all of the Friant Division contractors that could result from restoration flows required by the settlement. The settlement stipulates that water- and sediment-quality data be collected to help assess the restoration goals. This report summarizes and evaluates water-quality data collected in the main stem of the San Joaquin River between Friant Dam and the Merced River by the U.S. Bureau of Reclamation for the San Joaquin River Restoration Program during 2009–11. This summary and assessment consider sampling frequency for adequate characterization of variability, sampling locations for sufficient characterization of the San Joaquin River Restoration Program restoration reach, sampling methods for appropriate media (water and sediment), and constituent reporting limits. After reviewing the water- and sediment-quality results for the San Joaquin River Restoration Program, several suggestions were made to the Fisheries Management Work Group, a division of the San Joaquin River Restoration Program that focuses solely on the reintroduction strategies and health of salmon and other native fishes in the river. Water-quality results for lead and total organic carbon exceeded the Surface Water Ambient Monitoring Program Basin Plan Objectives for the San Joaquin Basin, and results for copper exceeded the U.S. Environmental Protection Agency Office of Pesticide Programs’ aquatic-life chronic and acute benchmarks for invertebrates. One sediment sample contained detections of pyrethroid pesticides bifenthrin, lambda-cyhalothrin, and total permethrin at concentrations above published chronic toxicity thresholds.

Bifenthrin, a ubiquitous contaminant, impairs the development and behavior of the threatened Longfin Smelt during early life stages

American Chemical Society (ACS) | June 23rd, 2023

The Longfin Smelt (Spirinchus thaleichthys) population in the San Franscisco Bay/Sacramento-San Joaquin Delta (Bay-Delta) has declined to ∼1% of its pre-1980s abundance

The Longfin Smelt (Spirinchus thaleichthys) population in the San Franscisco Bay/Sacramento-San Joaquin Delta (Bay-Delta) has declined to ∼1% of its pre-1980s abundance and, as a result, is listed as threatened under the California Endangered Species Act. The reasons for this decline are multiple and complex, including the impacts of contaminants. Because the spawning and rearing seasons of Longfin Smelt coincide with the rainy season, during which concentrations of contaminants increase due to runoff, we hypothesized that early life stages may be particularly affected by those contaminants. Bifenthrin, a pyrethroid insecticide commonly used in agricultural and urban sectors, is of concern. Concentrations measured in the Bay-Delta have been shown to disrupt the behavior, development, and endocrine system of other fish species. The objective of the present work was to assess the impact of bifenthrin on the early developmental stages of Longfin Smelt. For this, embryos were exposed to 2, 10, 100, and 500 ng/L bifenthrin from fertilization to hatch, and larvae were exposed to 2, 10, and 100 ng/L bifenthrin from one day before to 3 days post-hatch. We assessed effects on size at hatch, yolk sac volume, locomotory behavior, and upper thermal susceptibility (via cardiac endpoints). Exposure to these environmentally relevant concentrations of bifenthrin did not significantly affect the cardiac function of larval Longfin Smelt; however, exposures altered their behavior and resulted in smaller hatchlings with reduced yolk sac volumes. This study shows that bifenthrin affects the fitness-determinant traits of Longfin Smelt early life stages and could contribute to the observed population decline.

California regulation of agricultural runoff

American Bar Association (ABA) | November 1st, 2017

Agriculture in California is a multibillion dollar industry that produces more than half of the nation’s fruits, nuts, and vegetables. But this comes at a cost. Agricul

Agriculture in California is a multibillion dollar industry that produces more than half of the nation’s fruits, nuts, and vegetables. But this comes at a cost. Agriculture is the primary source of water pollution, with irrigation and rainfall sweeping excess fertilizers and pesticides off the fields into adjoining waters and, over time, leaching into groundwater. As a result, waterbodies—spanning roughly 8,000 miles of rivers and streams and 300,000 acres of lakes, bays, and wetlands—are impaired.

Chlorinated Byproducts of Neonicotinoids and Their Metabolites: An Unrecognized Human Exposure Potential?

American Chemical Society (ACS) | January 14th, 2019

We recently reported the initial discovery of neonicotinoid pesticides in drinking water and their potential for transformation through chlorination and alkaline hydrolys

We recently reported the initial discovery of neonicotinoid pesticides in drinking water and their potential for transformation through chlorination and alkaline hydrolysis during water treatment. The objectives of this research were: (1) to determine if neonicotinoid metabolites are relevant to drinking water exposure and (2) to identify the products formed from chlorination of neonicotinoids and their metabolites. Desnitroimidacloprid and imidacloprid-urea, two known metabolites of imidacloprid, are documented for the first time in drinking water. Desnitro-imidacloprid was present above the lower level of detection (0.03 ng/L) in 67% of samples (six of nine) from drinking water systems but detectable in all samples (up to 0.6 ng/L). Although concentrations of desnitro-imidacloprid were lower than concentrations of the parent neonicotinoids, desnitro-imidacloprid exhibits significantly greater mammalian toxicity than imidacloprid. Using LC-HR-ToF-MS/MS analysis of  results from laboratory experiments, we propose structures for novel transformation products resulting from the chlorination of clothianidin, imidacloprid, desnitro-imidacloprid, imidacloprid-urea, and hydrolysis products of thiamethoxam. Formation of chlorinated neonicotinoid byproducts occurs at time scales relevant to water treatment and/or distribution for the imidacloprid metabolites (t1/2 values from 2.4 min to 1.0 h) and thiamethoxam hydrolysis products (4.8 h). Neonicotinoid metabolites in finished drinking water and potential formation of novel disinfection byproducts during treatment and/or distribution are relevant to evaluating the exposure and potential impacts of neonicotinoids on human health.

Comments on the Draft Pyrethroid Control Program and Research Plan

Delta Stewardship Council (Delta Council) | September 18th, 2023