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Analysis of Eight Oil Spill Dispersants Using Rapid, In Vitro Tests for Endocrine and Other Biological Activity
Citation:
JUDSON, R., M. T. MARTIN, D. REIF, K. A. HOUCK, T. B. KNUDSEN, D. ROTROFF, M. XIA, S. SAKAMURU, R. HUANG, P. SHINN, C. P. AUSTIN, R. J. KAVLOCK, AND D. J. DIX. Analysis of Eight Oil Spill Dispersants Using Rapid, In Vitro Tests for Endocrine and Other Biological Activity. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 44(15):5979-5985, (2010).
Impact/Purpose:
EPA’s Office of Research and Development was asked to evaluate the potential toxicity of eight oil spill dispersants, including Corexit 9500. Because of the need for rapid turnaround, it was decided to employ a series of in vitro, cell-based assays. One mode of toxicity that is of concern for dispersants is endocrine disruption (2), due to of the fact that nonylphenol ethoxylates (NPEs) are used in some of the dispersants as part of the surfactant component. NPEs can degrade to produce nonylphenol (3), which can strongly interact with the estrogen receptor (4-7). NPEs themselves have been shown to inhibit testicular growth in rainbow trout (8). Because of this fact, the focus of our in vitro studies was on measuring potential interaction of the dispersants with the estrogen receptor (ER) and the androgen receptor (AR).
Description:
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 ∼100 ppm. Two dispersants, JD 2000 and SAFRON GOLD, were significantly less cytotoxic than the others with LC50 values approaching or exceeding 1000 ppm.
URLs/Downloads:
Analysis of Eight Oil Spill Dispersants Using Rapid, In Vitro Tests for Endocrine and Other Biological Activity Fact Sheet (PDF, NA pp, 80 KB, about PDF)Analysis of Eight Oil Spill Dispersants Using Rapid, In Vitro Tests for Endocrine and Other Biological Activity
