SusChEM: Collaborative Research: Environmental Fate and Effects of Dichloroacetamide Safeners: An Overlooked Class of Emerging Contaminants?

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PI Names: John SiveyProposal Number: 1703796 Many of the herbicide formulations applied to crop fields include a safener. Safeners are so-called "inert" ingredients, which are added to protect crops (but not weeds) from possible damage caused by herbicides. Safeners have application rates on par with many herbicide active ingredients; however, unlike most herbicide active ingredients, the environmental fate and effects of safeners are poorly understood. The purpose of this project is to address the extensive knowledge gaps associated with the environmental fate and ecological effects of a major class of safeners. This collaborative project unites a multidisciplinary team of experts and students from a primarily undergraduate institution (Towson University) and a doctoral-granting institution (University of Iowa) with the goal of promoting sustainable agricultural practices related to the use of safeners. This project seeks to advance our understanding of the environmental persistence and ecotoxicological risks of dichloroacetamide safeners and their transformation products. Despite being classified as "inert", safeners are biologically active and their bioactivity is anticipated to increase via selected environmental transformations (including photolysis and reductive dechlorination). Due to their extensive use, safeners likely represent an overlooked class of emerging contaminants. Using commercial safeners and their herbicidal co-formulants, this project will (1) determine their rates and mechanisms of photochemical transformation in surface waters; (2) quantify their extent of removal and/or transformation during simulated drinking water treatment; (3) establish timescales associated with their biotransformation; (4) identify products of these transformations, including how reactions alter enantiomeric signatures of chiral safeners; and (5) evaluate ecotoxicological risks of safeners and their transformation products toward non-target aquatic organisms. Commercial formulations can include enantiomerically-enriched herbicides co-formulated with racemic mixtures of safeners. As such, experiments will include individual safener enantiomers, safener racemates, and safener + herbicide binary mixtures representative of commercial formulations. As safener use is projected to increase in the future, there is urgent need to obtain reliable environmental assessment data for this chemical class. This project will provide some of the first non-industrial data necessary to assess persistence and risk associated with safeners in natural and engineered aquatic systems. Moreover, as dichloroacetamide safeners are applied extensively to corn used for food, animal feed, and biofuel production, this work confronts challenges to sustainable development at the food-energy-water nexus. As society grows increasingly reliant on agrochemical advances to feed a swelling population, this work promotes sustainable agriculture by guiding the design of environmentally-benign safener formulations. Central to this project is a research partnership between a PUI (Towson University) and an R1 (University of Iowa). A signature effort of this partnership is the participation of undergraduates in the Summer Research Opportunities Program (SROP) at the University of Iowa. SROP provides promising underrepresented students with research experience, in addition to workshops and seminars designed to enhance academic success and promote graduate education in STEM. In total, two graduate and several undergraduate students will receive training at the interface of environmental engineering, analytical chemistry, and toxicology, which will help to better prepare tomorrow's research leaders and technical workforce to confront the multi-faceted challenges at the food-energy-water nexus.