title: Analysis of eight oil spill dispersants using rapid, in vitro tests for endocrine and other biological activity.
abstract: The Deepwater Horizon oil spill has led to the use of >1 M gallons of oil spill dispersants, which are mixtures of surfactants and solvents. Because of this large scale use there is a critical need to understand the potential for toxicity of the currently used dispersant and potential alternatives, especially given the limited toxicity testing information that is available. In particular, some dispersants contain nonylphenol ethoxylates (NPEs), which can degrade to nonylphenol (NP), a known endocrine disruptor. Given the urgent need to generate toxicity data, we carried out a series of in vitro high-throughput assays on eight commercial dispersants. These assays focused on the estrogen and androgen receptors (ER and AR), but also included a larger battery of assays probing other biological pathways. Cytotoxicity in mammalian cells was also quantified. No activity was seen in any AR assay. Two dispersants showed a weak ER signal in one assay (EC50 of 16 ppm for Nokomis 3-F4 and 25 ppm for ZI-400). NPs and NPEs also had a weak signal in this same ER assay. Note that Corexit 9500, the currently used product, does not contain NPEs and did not show any ER activity. Cytotoxicity values for six of the dispersants were statistically indistinguishable, with median LC50 values approximately 100 ppm. Two dispersants, JD 2000 and SAF-RON GOLD, were significantly less cytotoxic than the others with LC50 values approaching or exceeding 1000 ppm.
authors.affiliation: National Center for Computational Toxicology, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA. judson.richard@epa.gov
authors.forename: Richard S
authors.initials: RS
authors.lastname: Judson
authors.forename: Matthew T
authors.initials: MT
authors.lastname: Martin
authors.forename: David M
authors.initials: DM
authors.lastname: Reif
authors.forename: Keith A
authors.initials: KA
authors.lastname: Houck
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Knudsen
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Rotroff
authors.forename: Menghang
authors.initials: M
authors.lastname: Xia
authors.forename: Srilatha
authors.initials: S
authors.lastname: Sakamuru
authors.forename: Ruili
authors.initials: R
authors.lastname: Huang
authors.forename: Paul
authors.initials: P
authors.lastname: Shinn
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Austin
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Kavlock
authors.forename: David J
authors.initials: DJ
authors.lastname: Dix
mesh_terms: D055884:Chemical Hazard Release; D052244:Endocrine Disruptors / Q000032:analysis*; D052918:Environmental Restoration and Remediation; D008055:Lipids / Q000633:toxicity; D011960:Receptors, Estrogen / Q000378:metabolism; D013501:Surface-Active Agents / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D052244:Endocrine Disruptors; D008055:Lipids; D011960:Receptors, Estrogen; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical; C470995:corexit 9500