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RESEARCH ARTICLE

1H NMR metabolomics of Eisenia fetida responses after sub-lethal exposure to perfluorooctanoic acid and perfluorooctane sulfonate

Brian P. Lankadurai A , André J. Simpson A and Myrna J. Simpson A B
+ Author Affiliations
- Author Affiliations

A Department of Chemistry, University of Toronto, 1265 Military Trail, Toronto, ON, M1C 1A4, Canada.

B Corresponding author. Email: myrna.simpson@utoronto.ca

Environmental Chemistry 9(6) 502-511 https://doi.org/10.1071/EN12112
Submitted: 31 July 2012  Accepted: 18 October 2012   Published: 10 December 2012

Environmental context. Perfluoroalkyl acids are persistent environmental contaminants that are also found in soils. We use a metabolomics approach based on nuclear magnetic resonance analyses to investigate the responses of earthworms to exposure to sub-lethal levels of two perfluoroalkyl acids. The results indicate that this metabolomics approach is able to delineate the toxic mode of action of contaminants present at sub-lethal levels.

Abstract. Metabolomics entails the analysis of endogenous metabolites within organisms exposed to an external stressor such as an environmental contaminant. We utilised 1H NMR-based metabolomics to elucidate sub-lethal toxic mechanisms of Eisenia fetida earthworms after exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). Earthworms were exposed to a range of concentrations of PFOA (6.25 to 50 μg cm–2) and PFOS (3.125 to 25 μg cm–2) by contact tests for 2 days. Earthworm tissues were extracted using a mixture of chloroform, methanol and water, and the polar fraction was analysed by 1H NMR spectroscopy. NMR-based metabolomic analysis revealed heightened E. fetida toxic responses with higher PFOA and PFOS exposure concentrations. Principal component analysis (PCA) exhibited significant separation between control and exposed earthworms along PC1 for all PFOA and PFOS exposure concentrations. Leucine, arginine, glutamate, maltose and adenosine triphosphate (ATP) are potential indicators of PFOA and PFOS exposure as these metabolite concentrations fluctuated with exposure. Our data also indicate that PFOA and PFOS exposure may increase fatty acid oxidation and interrupt ATP synthesis due to a disruption in the inner mitochondrial membrane structure. NMR-based metabolomics has promise as an insightful tool for elucidating the environmental toxicology of sub-lethal contaminant exposure.

Additional keywords: contact test, fatty acid oxidation, MOA, mode of action, PFOA, PFOS.


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