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Agrochemical Mixtures and Amphibians: The Combined Effects of Pesticides and Fertilizer on Stress, Acetylcholinesterase Activity, and Bioaccumulation in a Terrestrial Environment
Van Meter, R., R. Adelizzi, D. Glinski, AND Matt Henderson. Agrochemical Mixtures and Amphibians: The Combined Effects of Pesticides and Fertilizer on Stress, Acetylcholinesterase Activity, and Bioaccumulation in a Terrestrial Environment. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 38(5):1052-1061, (2019). https://doi.org/10.1002/etc.4375
Agrochemicals, primarily pesticides and fertilizers, are used regularly in an effort to control damaging crop organisms and increase crop productivity and yield. The widespread use of chemicals in agriculturally intensive landscapes poses a significant risk for non-target organisms, both during and after application. Amphibians are one non-target species group that traverse long-distances, to and from breeding ponds, often through croplands, leaving them vulnerable to agrochemical exposure (Mann et al. 2009; Berger et al. 2012; Fryday & Thompson 2012; Lendhardt et al. 2015). Population loss among many amphibian taxa is a prevalent and a well-known conservation concern (e.g., Stuart et al. 2004; Pounds et al. 2006; Alford et al. 2006). Understanding the potential role that agrochemicals play in amphibian declines is essential for both short- and long-term population sustainability.
Tank mixtures are popular within the agricultural community because they are time‐ and cost‐effective, but field applications leave nontarget organisms at risk of exposure. We explored the effects of a common herbicide (atrazine and alachlor) and fertilizer (urea) tank mixture on juvenile frog corticosterone stress levels, acetylcholinesterase (AChE) activity, and pesticide bioaccumulation. Single agrochemical or tank mixtures were applied to terrestrial microcosms, and then individual Southern leopard frog (Lithobates sphenocephala) juveniles were added to microcosms for an 8‐h exposure. Afterward, frogs were transferred to aquatic microcosms for 1 h to monitor corticosterone prior to euthanasia, brain tissues were excised to evaluate AChE, and tissue homogenates were analyzed for pesticide bioconcentation with gas chromatography–mass spectrometry. Atrazine significantly increased corticosterone in frogs, particularly when combined with alachlor and urea. Atrazine increased AChE and urea decreased AChE, although no interactive effects of chemical combinations were discernible. Relative to their individual treatments, the complete tank mixture with all 3 agrochemicals resulted in 64% greater bioconcentration of atrazine and 54% greater bioconcentration of alachlor in frog tissues. Our results suggest that agrochemical mixtures as well as their active ingredients can lead to altered stress levels and impaired physiological responses in amphibians. An improved understanding of the effects of co‐exposure to environmental contaminants in amphibians is important in assessing the ecological risks these compounds pose.
Record Details:Record Type: DOCUMENT (JOURNAL/PEER REVIEWED JOURNAL)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL EXPOSURE RESEARCH LABORATORY
EXPOSURE METHODS & MEASUREMENT DIVISION
INTERNAL EXPOSURE INDICATORS BRANCH