Non-active substances in agriculture, medicine, and other everyday items have generally been disregarded as possible pollutants in drinking water supplies. Nevertheless, although these compounds are inactive in specific products, they can still present dangers when they interact with different substances during the water treatment process.
A recent investigation conducted by scholars from the McKelvey School of Engineering at Washington University in St. Louis illustrates the extent of this effect. Jean Brownell, a postgraduate student collaborating with Kimberly Parker, an associate professor specializing in energy, environmental, and chemical engineering, spearheaded the research. Brownell studied the application of amines in herbicides and their potential function as precursors to nitrosamines, detrimental byproducts produced during water disinfection.
Brownell found that inactive amines, utilized as stabilizers in herbicides to improve solubility and minimize drift, may play a more significant role than active ingredients in the formation of disinfection byproducts (DBPs) associated with various health dangers, although effects differ by location and time. The findings were published in the April 15 edition of Water Research.
“Everyone needs nutritious food and clean drinking water, so there’s a clear reason for us to investigate how herbicides used in agriculture affect water treatment downstream,” stated Brownell. “We require herbicides to facilitate effective contemporary farming, but it’s also essential to reassess our beliefs about these products to ensure we haven’t overlooked adverse effects that may threaten public health and safety. That’s why we’re analyzing changes in herbicide usage trends over the last two decades that have not yet been reevaluated with respect to their influence on chemical precursors of DBPs.”
Brownell compared the yearly usage of amines in herbicides with other recognized nitrosamine precursors, such as the commonly used medications ranitidine and metformin. She observed that the application of amines in herbicide blends has risen in recent decades, particularly impacting regions such as the Midwest.
Due to the substantial quantity of amines employed, Brownell determined that these inactive compounds are potentially more significant as nitrosamine precursors than earlier assumptions suggested. Amines sourced from herbicides might enter the environment at rates comparable to those of precursors originating from pharmaceuticals. This could have considerable ramifications for water treatment processes, as nitrosamines are recognized to pose serious health threats even at minimal concentrations.
“We always want to identify the precursors and their origins,” Parker remarked. “The established belief was that the primary source of nitrosamine precursors was consumer goods—items like pharmaceuticals, fabric dyes, and so on—that enter the ecosystem through municipal wastewater, and agricultural runoff wasn’t seen as a major contributor. However, when agricultural practices shift, we cannot continue to rely on outdated findings. We must adapt our research and challenge our assumptions to confirm that our conclusions are either universally applicable or, alternatively, should be tailored to specific local contexts.”
Brownell’s examination reinforces that evolving trends in herbicide formulation and usage require a more meticulous investigation of nitrosamine precursors. Such studies must occur at distinct locations and times of the year to accommodate variations across space and time, which Brownell found could be substantial and impactful. Brownell and Parker also emphasized the critical need for gathering and sharing high-quality data from farmers and agencies across different regions to promote consistent best practices for food and water safety.
“This paper raises questions that call for further research to seek answers,” Parker indicated. “We do need to reevaluate our notions that led us to underestimate agriculture’s role in nitrosamine precursors, but this must be pursued through fieldwork to assess and confirm these observations.”
Brownell JM, Chen M, Parker KM. Making waves: Formulation components used in agriculture may serve as significant precursors for nitrogenous disinfection byproducts. Water Research, April 15, 2025. DOI: https://doi.org/10.1016/j.watres.2025.123116
This research is funded by the National Science Foundation (ECO–CBET 2033714, 2344232) and the Monticello College Foundation/Washington University in St. Louis (Spencer T. and Ann W. Olin Fellowship for Women in Graduate Study to J.M. Brownell).
Initially published on the McKelvey Engineering website
The article Inactive components in agricultural runoff could contribute to drinking water hazards first appeared on The Source.