Pesticide transformation products are nearly ubiquitous in small U.S. streams

Release Date:

Pesticide transformation products (TPs) may be a critical missing piece of the toxicity puzzle for aquatic life in small U.S. streams, according to a new study by the USGS.

The continental-scale study of pesticide TPs, the most geographically extensive to date, reveals the near-ubiquity of these chemicals in small U.S. streams. One or more TPs were detected in nearly 90% of 442 small U.S. streams investigated during 2013–2017. The most frequently detected TPs were degradates of nine herbicides, one insecticide, and two fungicides; the summed concentrations of these transformation products frequently exceeded the concentration of the parent pesticide.

The “disappearance” of a pesticide in the environment often is a result of incomplete degradation (transformation) that creates one or more pesticide TPs—new chemicals related to but different from the parent pesticide. Many TPs are less toxic to aquatic life than the parent, but some are more toxic. However, toxicity information is available for only about one quarter of the 117 TPs analyzed for this study.  A toxicity analysis using the assumption that TPs have the same toxicity as their parent pesticide indicates that potential aquatic effects of pesticide-related compounds could be underestimated by an order of magnitude or more.

TPs were commonly detected during baseflow conditions, implicating groundwater as an important source of TPs to streams. The presence of TPs in baseflow indicates chronic and potentially long-term environmental exposures of aquatic life to TPs.

Related Content

Filter Total Items: 4
Date published: March 4, 2019
Status: Active

National Water-Quality Assessment (NAWQA)

Our surface water, groundwater, and aquatic ecosystems are priceless resources, used by people across the Nation for drinking, irrigation, industry, and recreation. The National Water-Quality Assessment (NAWQA) Project is a leading source of scientific data and knowledge for development of science-based policies and management strategies to improve and protect our water resources.

Contacts: Mindi Dalton
Date published: March 1, 2019
Status: Active

Pesticides and Water Quality

Pesticides are chemicals designed to kill pests, including insects (insecticides), weeds (herbicides), and fungi (fungicides). The USGS assesses the occurrence and behavior of pesticides in streams, lakes, and groundwater and the potential for pesticides to contaminate our drinking-water supplies or harm aquatic ecosystems.

Contacts: Lisa Nowell
Date published: February 28, 2019
Status: Active

Regional Stream Quality Assessment (RSQA)

The goals of the Regional Stream Quality Assessment (RSQA) are to characterize multiple water-quality factors that are stressors to aquatic life (contaminants, nutrients, sediment, and streamflow alteration) and to develop a better understanding of the relation of these stressors to ecological conditions in streams throughout the region.

Attribution: Water Resources
Date published: September 17, 2018
Status: Active

Stream Ecology

Who lives in your stream? Rivers and streams, even small ones, are teeming with a vast number of species, including fish, aquatic invertebrates, and algae. Stream ecology is the study of those aquatic species, the way they interrelate, and their interactions with all aspects of these flowing water systems.

Filter Total Items: 3
Date published: January 29, 2021

Pesticide and transformation product concentrations and risk quotients in U.S. headwater streams

This dataset includes a subset of previously released pesticide data (Morace and others, 2020) from the U.S. Geological Survey (USGS) National Water Quality Assessment Program (NAWQA) Regional Stream Quality Assessment (RSQA) project and the corresponding hazard index results calculated using the R package toxEval, which are relevant to Mahler and others, 2020.

Date published: December 22, 2020

Non-linear baseflow separation model with parameters and results

This data release provides source code and an R workspace with functions comprising a non-linear baseflow separation model, calibrated values of parameters and estimates of the baseflow component of daily streamflow at selected streamflow gages. Parameter values were determined by calibration of the model. Estimates of the baseflow component include daily values and the total baseflow as a...

Date published: March 26, 2020

Concentrations of pesticides in sediment in 82 streams and in biofilms in 54 streams in California in 2017

Hydrophobic (sediment-associated) pesticides were measured in sediment samples collected from 82 wadeable streams and in biofilm in 54 of those streams in the Central California Foothills and Coastal Mountains ecoregion.115 current-use and 3 legacy pesticides were measured in stream sediment; 93 of the current-use pesticides and the same 3 legacy pesticides were measured in biofilm. On aver...