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USGS Mendenhall Postdoctoral  Research Fellowship Program

S13. Advancing Environmental Analytical Chemistry Techniques to Link Current-use Pesticide Exposure to Effects on Birds

A wide variety of pesticides are applied to agricultural and urban areas throughout the United States and are transported off-site either dissolved in water, bound to sediments, or by aerial drift during application. The effects of these current-use pesticides on ecosystem health are not well understood. Pesticide residues in tissues of non-target organisms demonstrate exposure and may serve as a metric that can be linked to biological endpoints. Recent studies of legacy pollutants have shown that tissue concentrations are potentially a better surrogate for characterizing toxicity to non-target organisms than traditional toxicity tests using external exposure concentrations (water, sediment, diet). Relatively little data are available on the occurrence of current-use pesticides in non-target organisms, and rarely are linkages between tissue concentration and toxicological endpoints established for many of these compounds. To better assess potential ecosystem effects, the first step is to characterize pesticide exposure to organisms of concern by directly measuring concentrations in tissue. The postdoctoral fellow is expected to develop an analytical method to measure current-use pesticides and potential metabolites in blood.

Because organisms are typically exposed to complex mixtures of pesticides, method development is focused on multi-residue methods which include as many pesticides as possible. Current-use pesticides vary considerably in their physical–chemical properties, which makes it difficult to develop multi-residue methods for different environmental media. USGS has developed a series of analytical methods to analyze over 100 current-use pesticides and degradates in tissues that vary widely in their lipid content. Whole body or individual organs are extracted by pressurized liquid extraction, followed by further cleanup using gel-permeation chromatography and various solid-phase extraction cartridges. Both gas-chromatography and liquid-chromatography platforms are used for analysis. Laboratory and field studies have shown that current-use pesticides do accumulate in aquatic organisms, including amphibians, crabs and crab embryos, fish, shorebird eggs, and black fly larvae (Smalling et al., 2010, 2013a, 2013b; Wilson et al., 2014). The next step is to analyze blood which will allow non-lethal sampling of fish or wildlife. Comparative analysis of blood, liver, and muscle of largemouth bass and alligators has shown that current-use pesticides are primarily detected in blood (Wieser et al., 2013; Wiebe et al., 2013).

Bird populations are declining throughout the US and pesticides are thought to be one potential cause. Although legacy organochlorine pesticides, such as DDT and its metabolites, were shown to cause chronic effects on bird reproduction, much less is known about the effects of current-use pesticides. Ingestion is considered the most significant route of exposure (Zhang et al., 2015) through ingesting treated seeds or eating insects, fish or smaller mammals that have accumulated pesticides.

This Mendenhall Opportunity provides a place for a scientist with a strong background in environmental analytical chemistry and an interest in toxicology to conduct interdisciplinary research on pesticides and birds. The goal of research under this Opportunity is aimed at providing critical knowledge on the exposure of birds to current-use pesticides in various environments.

The postdoctoral fellow is expected to develop an analytical method to measure select current-use pesticides and potential metabolites in blood using GC/MS/MS and LC/MS/MS platforms. Pesticides of particular interest include the second-generation rodenticides, neonicotinoid insecticides, and newer fungicides. The proposed project is expected to use a combination of laboratory and field studies to assess exposure and subsequent accumulation of pesticides in birds. Laboratory studies could involve controlled exposure of standard bird or fish models to pesticides and range from measuring residues in blood to more complex toxicokinetics to track the movement of pesticide and metabolites through the body. Exposure studies will need to be done in collaboration with other USGS scientists having the expertise and facilities to raise and conduct controlled exposures. Field studies could involve measuring residues in blood of wild birds or fish and include correlation of residues to effects, comparing species differences, dietary differences, or tracking potential exposure routes. Ultimately these results will be used in multidisciplinary collaborations with toxicologists and ecologists studying effects of contaminants on condors and golden eagles, quail and other seed-eating birds, insectivorous birds, and fish.


Smalling, K.L., Morgan, S., and Kuivila, K.K., 2010, Accumulation of current-use and organochlorine pesticides in crab embryos from northern California, USA, Environ. Toxicol. Chem., v. 29(11), p. 2593-2599.

Smalling, K.L., Fellers, G.M, Kleeman, P.M, Kuivila, K.M, 2013a, Accumulation of pesticides in Pacific Chorus frogs (Pseudacris regilla) from California’s Sierra Nevada Mountains, USA, Environ. Toxicol. Chem., v. 32(9), p. 2026-2034.

Smalling, K.L, Kuivila, K.M, Orlando, J.L., Phillips, B.M, Anderson, B.A., Siegler, K., Hunt, J.W., Hamilton, M., 2013b, Environmental fate of fungicides and other current-use pesticides in a central California estuary, Marine Poll. Bull., v. 73, p.144–153.

Wilson, E.R., Smalling, K.L., Reilly, T.J., Gray, E, Bond, L., Steele, L., Kandel, P., Chamberlin, A., Gause, J., Reynolds, N., Robertson, I., Novak, S., Feris, K., and White, M.M., 2014, Assessing the Potential Effects of Fungicides on Nontarget Gut Fungi (Trichomycetes) and their Associated Larval Black Fly Hosts, J. Am. Water Resour. Assoc., v. 50(2), p.420-433.

Wiebe, J.J., Rice, K., Wieser, C.M., Gross, T.S., 2003, U.S. Geological Survey Greater Everglades Science Program: 2002 Biennial Report, An Evaluation of Contaminant Exposures and Potential Effects on Health and Endocrine Status for Alligators in the Greater Everglades Ecosystem, Open-File Report 03-54.

Wieser, C.M., Wiebe, J.J., Ruessler, D.S., Gross, T.S., Lange, T., 2003, U.S. Geological Survey Greater Everglades Science Program: 2002 Biennial Report, An Evaluation of Contaminant Exposures and Potential Effects on Health and Endocrine Status for Largemouth Bass in the Greater Everglades Ecosystem, Open-File Report 03-54.

Zhang, C., Cheng, F., Sun, L., Zhuang, S., Li, W., Liu, G., Lee, P.W., Tang, Y., 2015, In silico prediction of chemical toxicity on avian species using chemical category approaches, Chemosphere, vol. 122, p.280–287.

Proposed Duty Station: Sacramento, CA

Areas of Ph.D.: Environmental chemistry, environmental toxicology, environmental engineering (candidates holding a Ph.D. in other disciplines but with knowledge and skills relevant to the Research Opportunity may be considered).

Qualifications: Applicants must meet one of the following qualifications: Research Chemist. (This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the USGS Human Resources specialist.)

Research Advisor(s): Kathryn Kuivila, (503) 251-3257,; Michelle Hladik, (916) 278-3183,

Human Resources Office Contact: Michelle Liu,, (916) 278-9449.

How to apply for a Mendenhall Fellowship: Go to

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Last modified: 10:52:08 Thu 15 Oct 2015
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