title: Comparative in vitro toxicity assessment of perfluorinated carboxylic acids.
abstract: Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are synthetic fluorinated compounds that are highly bioaccumulative and persistent organic pollutants. Perfluorooctanoic acid (PFOA), an eight-carbon chain perfluorinated carboxylic acid, was used heavily for the production of fluoropolymers, but concerns have led to its replacement by shorter carbon chain homologues such as perfluorohexanoic acid (PFHxA) and perfluorobutanoic acid (PFBA). However, limited toxicity data exist for these substitutes. We evaluated the toxicity of PFOA, PFHxA and PFBA on a zebrafish liver cell line and investigated the effects of exposure on cell metabolism. Gross toxicity after 96 h of exposure was highest for PFOA and PFO-, while PFHxA and PFBA exhibited lower toxicity. Although the structural similarity of these compounds to fatty acids suggests the possibility of interference with the transport and metabolism of lipids, we could not detect any differential expression of peroxisome proliferator-activated receptor (ppar-α, -β and -γ), fabp3 and crot genes after 96 h exposure to up to 10 ppm of the test compounds. However, we observed localized lipid droplet accumulation only in PFBA-exposed cells. To study the effects of these compounds on cell metabolism, we conducted fluorescence lifetime imaging microscopy using naturally fluorescent biomarkers, NADH and FAD. The fluorescence lifetimes of NADH and FAD and the bound/free ratio of each of these coenzymes decreased in a dose- and carbon length-dependent manner, suggesting disruption of cell metabolism. In sum, our study revealed that PFASs with shorter carbon chains are less toxic than PFOA, and that exposure to sublethal dosage of PFOA, PFHxA or PFBA affects cell metabolism. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Purdue University, Department of Forestry and Natural Resources, West Lafayette, IN, 47907, USA.
authors.forename: Cecon T
authors.initials: CT
authors.lastname: Mahapatra
authors.affiliation: Bindley Bioscience Center, Purdue University, West Lafayette, IN, USA.
authors.forename: Nur P
authors.initials: NP
authors.lastname: Damayanti
authors.affiliation: Purdue University, Department of Forestry and Natural Resources, West Lafayette, IN, 47907, USA.
authors.forename: Samuel C
authors.initials: SC
authors.lastname: Guffey
authors.affiliation: Purdue University, Department of Forestry and Natural Resources, West Lafayette, IN, 47907, USA.
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Serafin
authors.affiliation: Bindley Bioscience Center, Purdue University, West Lafayette, IN, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Irudayaraj
authors.affiliation: Purdue University, Department of Forestry and Natural Resources, West Lafayette, IN, 47907, USA.
authors.forename: Maria S
authors.initials: MS
authors.lastname: Sepúlveda
mesh_terms: D000818:Animals; D001692:Biological Transport; D015415:Biomarkers / Q000378:metabolism; D002208:Caproates / Q000633:toxicity*; D002210:Caprylates / Q000633:toxicity*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004785:Environmental Pollutants / Q000633:toxicity*; D005466:Fluorocarbons / Q000633:toxicity*; D015870:Gene Expression / Q000187:drug effects; D050356:Lipid Metabolism / Q000187:drug effects* / Q000235:genetics; D008099:Liver / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D008856:Microscopy, Fluorescence; D013329:Structure-Activity Relationship; D015027:Zebrafish
chemical_list: D015415:Biomarkers; D002208:Caproates; D002210:Caprylates; D004785:Environmental Pollutants; D005466:Fluorocarbons; C033094:perfluorobutyric acid; C023036:perfluorooctanoic acid; C479228:perfluorohexanoic acid
keywords: Fluorescence Lifetime Imaging Microscopy; Liver; Perfluoroalkyl substances; Perfluorobutanoic acid; Perfluorohexanoic acid; Zebrafish