The Toxicologist - Society of Toxicology

contribution of epigenetics to complex disease phenotypes appears to be very large,
i.e. between 70% and >97%. The interaction of Mendelian genetics (changes in
DNA sequence) with Lamarckian genetics (no alterations in DNA sequence; i.e.
epigenetics) will be emphasized in this overview presentation.
825 TOXICOLOGICAL CONSIDERATIONS IN THE GULF
OF MEXICO OIL SPILL.
M. C. Madden. ORD, NHEERL, HSD, Clinical Research Branch, U.S. EPA,
Chapel Hill, NC.
The Deepwater Horizon oil rig explosion on April 20, 2010 resulted in a release of
petroleum crude oil into Gulf of Mexico waters. The release, 41 miles offshore, was
about 1 mile in depth. Oil dispersants were employed to change surface oil and underwater
properties. Surface oil was also combusted and physical barriers deployed.
Oil was estimated to have spread to an estimated 2500 square mile in the Gulf. On
July 15, the well head was capped reducing oil flow to a minimum. A number of exposure
uncertainties have arisen as a result of the spill related to the locations the oil
has dispersed to, including volatilization to the atmosphere; and the dose of contaminant
reaching wildlife, humans, and vegetation in the affected areas, and
physicochemical properties of the dispersant-treated and aged oil. We will present
findings related to understanding the migration of the spill components, the habitats
and organisms contaminated, and the characteristics of altered crude. Routes of
exposure for humans to oil components will be presented in part based on data
from other studied oil spills. Knowledge of these currently unsure parameters will
assist in understanding the potential biological and health effects induced by the
spill. The major possible ecological effects will be described and compared to the
normal Gulf ecosystem dynamics. The choice of the specific oil dispersants utilized
will be discussed with an emphasis on the toxicity assays employed; toxicity endpoints
still not fully examined will be identified. The types and likelihood of possible
human adverse health effects, both acute and latent, will be presented in light of
what will be known of the exposure routes and the conditions (e.g. heat). In order
to comprehend possible effects in a comprehensive manner in order to develop estimates
of various risks, the data sources available to perform such an assessment will
be identified (e.g., estimates of contaminated seafood consumption). Finally, data
deficiencies needed for risk assessment will be described.
826 THE GULF OF MEXICO ECOSYSTEM:
CONSEQUENCES OF THE BP OIL SPILL.
W. Benson, S. Jordan, R. Greene, V. Engle, M. Hemmer and M. Barron. Gulf
Ecology Division, U.S. EPA, Gulf Breeze, FL.
The Gulf of Mexico, a semi-enclosed basin of the Atlantic Ocean, is bounded by 5
U.S. states, Mexico, and Cuba. Its shorelines mostly adjoin low-lying coastal plains,
where extensive estuaries, marshes, barrier islands, and shallows provide outstanding
habitats for fish, shellfish, and wildlife. Seaward, the broad continental shelf
drops off to the abyssal zone, >3000 m deep, thus the Gulf is endowed with a full
range of marine habitats. The abundance of physical habitats and a climate spanning
warm temperate, sub-tropical, and tropical zones combine to make the Gulf
one of the world’s most productive bodies of water, a center of biodiversity, and
home to major commercial and recreational fisheries. Since the April 2010 explosion
of the Deepwater Horizon oil exploration platform, unprecedented quantities
of crude oil have been released into the Gulf. Nearly 2 million gallons of oil dispersant
have been applied. It is far too early to know the total damage to the Gulf’s
ecosystem, but comprehensive baselines of data are available for estuaries, coastal
waters, and wetlands as a result of surveys conducted by EPA and partners. An EPA
report was prepared in response to the disaster that summarizes historical and immediate
(2010) ecological baseline conditions for Gulf estuaries, including water
and sediment quality, fish tissue contaminants, and other indicators. This baseline
will be used for comparison with current and future monitoring data to detect
changes in condition. Additional reports by EPA examined the acute toxicity of dispersants,
oil, and dispersant-oil mixtures on sensitive Gulf aquatic species, but the
full extent of toxicological effects on aquatic species and other wildlife remain unknown.
The best case scenario for the Gulf ecosystem is that the major effects of the
oil disaster will be local in extent and short-lived. The worst case is that pervasive effects,
especially chronic toxicity, will be widespread, enduring, and disruptive of reproduction
and survival for fish, invertebrates and wildlife.
827 THE FATE, BEHAVIOR, AND WEATHERING OF SPILLED
OIL FROM THE DEEPWATER HORIZON SPILL.
J. Michel. Research Planning, Inc., Columbia, SC. Sponsor: M. Madden.
The oil from the Deepwater Horizon spill had unique fates,, behaviors, and
weathering patterns because of the release from 5,000 feet below the water surface
and the chemical composition of the oil. However, the oil did follow expected pat-
178 SOT 2011 ANNUAL MEETING
terns based on our understanding of oil behavior in the environment. These patterns
of oil fate and behavior affect the toxicity of the oil, both to water column
and shoreline resources. An understanding of these properties would help predict
the possible toxicity of the pollutant and what species would potentially be exposed.
This presentation will discuss the physicochemistry & fate of oil in seawater,
with some emphasis on the type of oil spilled, weathering changes in different
environments (water column, water surface, and shoreline), pathways of exposure,
the habitats that were affected, and the different response options used to reduce
overall impacts.
828 OIL SPILL CHEMICAL DISPERSANTS: THE GOOD,
THE BAD, OR THE UGLY?
C. L. Mitchelmore. Center for Environmental Science, University of Maryland,
Solomons, MD. Sponsor: M. Madden.
The use of chemical dispersants following an oil spill event has always been a controversial
issue. Their use during the Deepwater Horizon oil leak has again raised issues
regarding the numerous data gaps and uncertainties on their impacts on organisms,
especially in the long-term, to many understudied and sensitive taxa (e.g.
corals). Their use in this specific incident has brought into question further issues
given the extent of their use (1.8 million gal. over 3 months) and their novel use directly
at the wellhead 5000 ft underwater. During this spill intense scrutiny was
placed on the specific types of dispersants being using (Corexit 9527 and 9500A)
and calls for using less toxic alternatives or stopping altogether were heavily reported
issues. This presentation will give an overview on what is and isn’t known
about the toxicity of the chemical dispersants listed on the National Contingency
Plan Product Schedule, including an analysis of past and current data sets and an
overview of some of the limitations regarding these toxicity tests. The presentation
will evaluate whether enough sufficient toxicity data exists to make rationale decisions
about their use, and what are the major uncertainties and data gaps. We have
recently attempted to fill some of these data gaps in understudied, sensitive taxa, by
exposing corals to oil (weathered Arabian Light crude oil), dispersant (Corexit
9500A) and chemically-dispersed oil using environmentally realistic, controlled
and fully-chemically characterized laboratory test solutions. In comparison to other
species, our data shows that the soft coral (Xenia elongata) is impacted at the population
level by short-term (8hr), low-levels (ppm) of Corexit 9500A and chemicallydispersed
oil. Exposure to oil components occurred from both the dissolved and
particulate oil phases resulting in delayed mortality and a variety of sub-lethal biological
effects. We recommend that further experiments should characterize the response
of hard coral species and in the meantime careful trade-off decisions should
be made when considering dispersant use in or near a coral reef.
829 SHORT-TERM HEALTH EFFECTS FROM OIL SPILLS.
N. Sathiakumar. University of Alabama at Birmingham, Birmingham, AL. Sponsor:
M. Madden.
The Gulf of Mexico oil spill is the largest accidental release of oil into marine waters
causing considerable concern on the potential human health effects from exposure
to the massive quantities of spilled oil and the chemical dispersants used in cleanup
operations. Much of the knowledge on human health effects following exposure to
spilled oil comes from epidemiologic studies of supertanker oil spills. Of 38 supertanker
spills since 1980s, only 7 have been studied. The available studies provide
consistent evidence of short-term toxic symptoms involving ocular, respiratory and
neurological systems and of psychological symptoms among exposed community
members and among cleanup/volunteer workers. In addition, certain subgroups of
cleanup/volunteer workers had a high frequency of dermal symptoms besides other
toxic symptoms, ergonomic symptoms such as back pain and work-related injuries.
Durations of employment in cleanup operations was identified as a risk factor. The
use of personal protective equipment (PPE) was less than optimal among volunteer
workers. Poorly-informed workers on PPE use had an increased risk of exposure.
Selected biochemical measurements for kidney and liver functions and/or spirometry
for lung function among exposed community members, subgroup of children
and cleanup workers were within normal limits. One study suggests that genotoxic
and endocrine function alternations may be related to exposure, whereas another
study found no evidence of genotoxicity damage. In conclusion, the short-term
health effects of oil spills are primarily acute toxic symptoms and impairment of
psychological health. No firm conclusion can be drawn on systemic effects or of
genotoxicity as the relevant data are available only at a single point in time.
Considerable uncertainty remains with regard to the potential for long-term health
effects. Identification of the magnitude of the short-term effects will assist in devising
strategies to limit exposures and control adverse health outcomes, particularly
among vulnerable populations. Long-term biomonitoring studies of high risk populations
are needed to evaluate the potential long-term health effects following oil
spill-related exposures.