preparation of dispersant and oil water accommodated ... 2010 dwh testing program test 8 dispersants...
TRANSCRIPT
Office of Research and DevelopmentNHEERL, Gulf Ecology Division, Gulf Breeze, FL 32561Office of Research and DevelopmentNHEERL, Gulf Ecology Division, Gulf Breeze, FL 32561
Mace BarronUSEPA Office of Research and Development
Dispersant ToxicologyEfficacy and Effects
Insert/replace photos
Of relevance to EDC tests
Outline
• Overview of oil spill dispersant efficacy and effects
• EPA dispersant testing program
• Implications for spill response
Background Reports:
• NRC (2005) oil spill dispersant efficacy and effects
• RSC (2015) Canada expert report on oil behavior and impacts
• EPA journal articles on dispersant testing
www.nap.edu/catalog/11283/oil-spill
-dispersants-efficacy-and-effects
www.rsc-src.ca/sites/default/
files/pdf/OIW%20Report.pdf
3
What is a dispersant?
• Many products, varied components
• proprietary formulations of surfactants, light petroleum, solvents
• break oil into tiny droplets
• facilitates biodegradation, dilution
• effective on <30% weathered oil
• moves oil from slick into the water column
• tradeoff between surface/shoreline impacts and water column effects
• increased toxicity to aquatic organisms below the surface
www.nalcoesllc.com/nes/documents/MSDS/
NES-LLC-COREXIT-EC9500A-March_2012.pdf
www.nalcoesllc.com/nes/documents/MSDS/NESLLC-
COREXIT-_EC9527A-March_2012.pdf
Corexit MSDS
• similar composition; 9500A contains light petroleum distilates
• lab tests show similar toxicity and efficacy
• intrinsic toxicity of oil does not increase
• moderately toxic and much less toxic than oil
• chemically dispersed oil similar toxicity as physically dispersed oil
• increase the concentration of oil in the water column
• greater bioavailabilty to aquatic life
• reduce risks to shorelines and surface species
• increased risk to subsurface species (top 30 feet of water column)
• impacts to sub-surface resources less obvious
Principles of Dispersant Toxicology
EPA 2010 DWH Testing Program
Test 8 dispersants on NCP Product Schedule: • identify lower toxicity alternatives (EPA Administrator)
• verify information on NCP Product Schedule
• test Louisiana crude oil (SLC) instead of fuel oil #2
• concerns for nonylphenol ethoxylate degradation
Laboratory testing program:
• efficacy of oil+dispersant
• in vitro endocrine and cytotoxicity screening
• acute toxicity to two Gulf estuarine species
dispersant alone; SLC oil+dispersant
Lab Determination of Dispersant Effectiveness
• Baffled Flask Test (BFT) at 41 and 77 oF with SLC oil
• 3 of 8 satisfactory dispersion results (>70% efficacy)
• similar results at cold and warm temperatures SLC
• Corexit 9500A 75-80% lab dispersion
0
10
20
30
40
50
60
70
80
90
100
Me
an
DE
, %
*
5 ºC
25 ºC
p = 0.45
p = 0.068 p = 0.27
p = 0.059
p = 0.13
p = 0.051
p = 0.0026
p = 0.053
p = 0.33
Core
xit 9
500
Noko
mis
3F4
JD 2
000
Noko
mis
3AA
Saf
Ron G
old
ZI400
Sea
Bra
t #4
SLC
Alo
ne
80.4080.18
78.0975.35
72.9870.80
28.36
28.36
49.13
42.56 31.19
18.44
22.29
40.16
14.24
19.58
5.24 5.63
Dis
persi
t SPC
1000
53.24
9500
Cytotoxicity and Endocrine Screening
• only test dispersants (no oil)
• in vitro testing using 80 mammalian cell line assays
• determine cell death, estrogen and androgen receptor activity
• dispersant only: tested at concentrations up to 10,000 ppm
• similar results in all 8 dispersants
• no estrogenic or androgenic activity detected at 10,000 ppm
• test tube cell death above 10 ppm
Dis
persi
t SPC10
00
Noko
mis
3-A
A
Noko
mis
3-F
4
Core
xit 9
500A
ZI-400
Sea
Bra
t#4
Saf
-Ron G
old
JD-2
000
LC
50
(p
pm
)
1
10
100
1000
1
10
100
1000
EPA ORD
NCPPracticallyNon Toxic
SlightlyToxic
ModeratelyToxic
Comparison of EPA DWH and
NCP Dispersant-only test results
LessTo
xic
Oil-
Only
Noko
mis
3-A
A
Sea
Bra
t#4
JD-2
000
Dis
persi
t SPC10
00
Saf
-Ron G
old
Core
xit 9
500A
Noko
mis
3-F
4
ZI-400
LC
50 (
pp
m)
0.1
1
10
100
0.1
1
10
100
SlightlyToxic
ModeratelyToxic
HighlyToxic
Dispersant + oil Testing
• similar toxicity as oil alone
• dispersant-only less toxic
co
rexit
on
ly
LessTo
xic
co
rexit
+o
il
Conclusions from EPA DWH Testing
• max efficacy in lab ~80% dispersion
• in vitro toxicity in mammalian cell lines toxicity > 10ppm
• acute ecotox consistent with NCP dispersant testing
• dispersants less toxic than dispersant + oil mixtures
• Corexit 9500A: moderate toxicity; reasonable efficacy
New EPA Testing Program
• dilbits (diluted bitumens; Keystone, other transport)
develop baseline tox data fresh and weathered dilbits
marine, freshwater species; acute and sublethal testing
• crude oils (support for Subpart J proposed rule)
develop baseline data for new EPA reference oils (TBD)
evaluate selected dispersants to determine impact on listing
expand testing beyond 2 standard test species
evaluate and refine proposed toxicity test guidelines
• Effectiveness depends on:
– accuracy of application
– oil type and weathering (less effective on heavy, weathered oils)
– how well mixed with oil (sufficient wave energy)
• Reduce risks to shorelines and surface species (birds, turtles, dolphin)
• Increased risk to subsurface species (top 30 feet of water column)
– impacts to sub-surface resources less obvious
• Standard toxicity testing only evaluates short term exposures
– sublethal and long term effects possible; research ongoing
Implications for Spill Response
Determining Dispersant Use
• Will mechanical response be sufficient?
• Is the spilled oil known to be dispersible?
• Are sufficient chemical response assets available?
• Are environmental conditions conducive to successful application
and dispersion?
• Will application reduce water surface and shoreline impacts without
significantly increasing aquatic life impacts?
QUESTIONS?
Mace Barron
Gulf Ecology Division, U.S. EPA
1 Sabine Island Drive, Gulf Breeze FL 32561
(850) 934 9223