x>EPA
www.epa.gov/ord
science  in  ACTION
BUILDING A SCIENTIFIC FOUNDATION  FOR SOUND ENVIRONMENTAL DECISIONS
    US EPA's Oil Spill Dispersant Screening Results
    RAPID TESTING  FOR POTENTIAL ENDOCRINE RELATED ACTIVITY & CYTOTOXICITY
   The US Environmental Protection
   Agency and the U.S. Coast Guard
   have authorized BP to use oil spill
   dispersants as one tool in the
   response to the Deepwater Horizon
   oil spill. Preliminary testing results
   indicate that underwater use of
   dispersants is effective at reducing
   the amount of oil reaching the
   surface and allows the use of less
   dispersant than is needed once the
   oil reaches the surface. However
   because of the unprecedented
   volume of dispersants being used on
   the BP oil spill, there are questions
   about the potential hazard of the
   dispersants that have been used or
   are being considered for use.

   To address these questions, EPA
   used innovative research nationwide
   to conduct numerous rounds  of tests
   to compare eight of the 14
   commercially available oil spill
   dispersants for their relative
   potential to be harmful to the health
   of people and to aquatic species
   living in the Gulf. The first round of
   testing used fast, automated
   screening tests from EPA's Toxicity
   Forecaster (ToxCast), and the Tox21
   federal partnership with the NIH
   Chemical Genomics Center, to
   compare each dispersant's potential
   for endocrine activity and relative
   toxicity to living cells. The
   ToxCast/Tox21 screening results
   have been published in the journal
   Environmental Science and
   Technology.

   ToxCast/Tox21 screened the eight
   dispersants for potential endocrine
   activity due to the presence of the
   chemical nonylphenol ethoxylate
   (NPE) in some commercial

Dispersit SPC 1000
Nokomis 3-F4
Nokom is 3-AA
Zl 400
Sea Brat #4
Corexit9500
SAP-RON GOLD
JD2000


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                                          10
                                                   100
                                                             1000
                                                                      10000
            Figure 1: Toxicity data for the dispersants, combining data from 3 cell-based assays -with data
            on aquatic species. Each horizontal band shows the data for one dispersant. Cytotoxicity
            values (concentration at-which 50% lethality or effect is observed) are indicated by circles.
            Aquatic species LC50 values are indicated by triangles. Note that all dispersants -were tested in
            all assays, and missing data points indicate that no toxicity -was seen in that assay at the
            highest concentration tested (1000 ppm). 95% confidence intervals are shown for all assays.
            formulations. The presence of NPE
            could lead to endocrine disruption
            and impair reproductive function
            and development.

            EPA used over 80 rapid screening
            tests from the ToxCast and Tox21
            programs. These included multiple
            estrogen receptor (ER), and
            androgen receptor (AR) tests for
            endocrine activity, and multiple tests
            for cytotoxicity, which is a measure
            of how toxic a chemical is to living
            cells.

            A wide range of dispersant
            concentrations from 0.001 to 10,000
            parts per million (ppm) were tested,
            and overall results did not indicate
            biologically significant estrogenic or
            androgenic activity  for the
dispersants, although weak activity
was observed for two dispersants in
one estrogen receptor test.
Cytotoxicity was observed at
concentrations above 10 parts per
million for all of the dispersants.

In summary, EPA's results indicated
that none of the eight dispersants
tested, including the product in use
in the Gulf, displayed biologically
significant endocrine disrupting
activity. The tested dispersants alone
had relatively low potential for
cytotoxicity, with JD-2000 and SAP-
RON GOLD being the least
cytotoxic.


These data from ToxCast and Tox21
tests were combined with additional
EPA studies in the report published
           U.S. Environmental Protection Agency
           Office of Research and Development

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June 30, 2010 entitled Analysis of
Eight Oil Spill Dispersants Using In
Vitro Tests for Endocrine and Other
Biological A ctivity.


In progress are EPA studies on fish
and shrimp to determine the relative
toxicity of the oil and the dispersants
to aquatic species in the Gulf of
Mexico. Initial results on this testing
were published June 30, 2010 in the
report Comparative Toxicity of Eight
Oil Dispersant Products on Two
Gulf of Mexico Aquatic Test Species.

ToxCast is a multi-year, multi-
million dollar effort that uses
advanced science tools to help
understand how human body
processes are affected by exposure
to chemicals. It currently includes
500 fast, automated chemical
screening tests that have assessed
over 300 environmental chemicals.
The screening tests do not use
animals to assess the potential
toxicity of a chemical. ToxCast type
tests are routinely used by the
pharmaceutical industry to study  the
effects of drugs and by EPA to
assess environmental chemicals.

Tox21is a partnership between the
EPA, the NIH Chemical Genomics
Center, the National Toxicology
Program and the Food and Drug
Administration. The Tox21
collaboration pools federal agency
resources (research, funding and
testing tools) to develop ways to
more effectively predict how
chemicals will affect human health
and the environment. The goals are
to screen up to 10,000 widely used
environmental chemicals and drugs
through a battery of non-animal
based toxicity tests.

EPA's  ToxCast and Tox21
screening tools are part of the
Computational Toxicology Research
Program (CompTox). The goal of
CompTox is to provide fast,
automated tests for screening and
assessing chemical exposure, hazard
and risk

For more information:
www.epa.gov/comptox
www. epa. gov/toxcast
www.epa.gov/BPSpill

References
Judson et al. (2010) "Analysis of
Eight Oil Spill Dispersants Using
Rapid, In Vitro Tests for Endocrine
and Other Biological Activity"
Environmental Science and
Technology
(http://pubs.acs.org/doi/abs/10.1021/
esl02150z)

Originating Organization for Fact
Sheet
EPA

Primary Author of Fact Sheet
Monica Linnenbrink

Secondary Authors of Fact Sheet
Robert Kavlock, David Dix and
Richard Judson

First/Lead Author of Paper
Richard Judson

Contact:
Monica Linnenbrink
Office of Research & Development
National Center for Computational
Toxicology
919-541-1522
linnenbrink.monica@epa.gov
        U.S. Environmental Protection Agency
        Office of Research and Development

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