title: Comparative responses of freshwater organisms to exposures of a commercial naphthenic acid.
abstract: Comparative toxicity studies using unconfounded exposures can prioritize the selection of sensitive sentinel test species and refine methods for evaluating ecological risks of complex mixtures like naphthenic acids (NAs), a group of organic acids associated with crude oils and energy-derived waters that have been a source of aquatic toxicity. The objectives of this study were to compare responses of freshwater aquatic organisms (vertebrate, invertebrates, and a macrophyte; in terms of acute toxicity) to Fluka commercial NAs and to compare measured toxicity data with peer-reviewed toxicity data for other commercial NA sources and energy-derived NA sources. Exposures were confirmed using high performance liquid chromatography. Responses (7-d LC50s/EC50) ranged from 1.9 mg L(-1) for Pimephales promelas to 56.2 mg L(-1) for Typha latifolia. Following P. promelas in order of decreasing sensitivity were Ceriodaphnia dubia (7-d LC50 = 2.8 mg L(-1)), Hyalella azteca (7-d LC50 = 4.1 mg L(-1)), Chironomus dilutus (7-d LC50 = 6.5 mg L(-1)), and T. latifolia (7-d EC50 = 56.2 mg L(-1)), indicating that in terms of sensitivities, fish > invertebrates > plant for Fluka NAs in this study. Factors that affect exposures and measurements of exposures differ among commercial and energy-derived NAs and constrain comparisons. Despite differences in exposures, fish and invertebrates were relatively sensitive to both commercial and energy-derived NA sources (based on laboratory measurements and peer-reviewed data) and could be appropriate sentinel species for risk evaluations.
authors.affiliation: Department of Forestry and Environmental Conservation, 261 Lehotsky Hall, Clemson University, Clemson, SC 29634-0001, USA. Electronic address: cierakinley@gmail.com.
authors.forename: Ciera M
authors.initials: CM
authors.lastname: Kinley
authors.affiliation: Department of Forestry and Environmental Conservation, 261 Lehotsky Hall, Clemson University, Clemson, SC 29634-0001, USA.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: McQueen
authors.affiliation: Department of Forestry and Environmental Conservation, 261 Lehotsky Hall, Clemson University, Clemson, SC 29634-0001, USA.
authors.forename: John H
authors.initials: JH
authors.lastname: Rodgers
mesh_terms: D000818:Animals; D002264:Carboxylic Acids / Q000633:toxicity*; D003530:Cyprinidae / Q000378:metabolism*; D007448:Invertebrates / Q000187:drug effects*; D007928:Lethal Dose 50; D032401:Typhaceae / Q000187:drug effects*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D002264:Carboxylic Acids; D014874:Water Pollutants, Chemical; C046170:naphthenic acid
keywords: Commercial naphthenic acid; Comparative toxicity; Sentinel aquatic organisms