United States
Environmental Protection
Agency
Environmental Research
Laboratory
Gulf Breeze FL 32561
Research and Development
EPA-600/S4-84-055 Sept. 1984
&EPA Project Summary
Results of the Drilling Fluids
Research Program Sponsored by
the Gulf Breeze Environmental
Research Laboratory, 1976 -
1983, and Their Application to
Hazard Assessment
Thomas W. Duke and Patrick R. Parrish
This report summarizes a cooperative
research program supported by the
U.S. Environmental Protection Agency
(EPA) from 1976-1984 to evaluate the
impact of drilling fluids on the marine
environment. EPA issues permits for
the discharge of drilling fluids on the
U.S. Outer Continental Shelf (DCS)
under the National Pollutant Discharge
Elimination System (NPDES). Informa-
tion gained from this research program
and fully reported in a final report can be
used by EPA personnel and others
involved in the NPDES permitting
process.
The report is divided into four sections:
(1) a brief discussion of the uses and
characteristics of drilling fluids; (2) a
presentation of the results of the
research program, including a review of
pertinent publications resulting from
the program, data derived from chemi-
cal and biological studies of used
drilling fluid samples from the Gulf of
Mexico and from laboratory studies
with generic drilling fluids, a discussion
of environmental concentrations, and a
synthesis of fate and effects data
obtained through the Adaptive Environ-
mental Assessment (AEA) process; (3)
recent reviews and reports; and (4)
conclusions.
This Project Summary was developed
by EPA's Environmental Research
Laboratory, Gulf Breeze, FL, to announce
key findings of the research project that
are fully documented in a separate
report of the same title (see Project
Report ordering information at back).
Introduction
Drilling fluids (also called muds) are
essential to rotary drilling processes used
in exploratory and production wells on
the OCS. These fluids are pumped
through the drill pipe and drill bit and
returned to the surface, bringing sand,
rocks, and drill cuttings. The fluids
perform several important functions,
including cooling, lubrication, reduction
of corrosion, and maintenance of hydro-
static pressure. Drilling fluids contain a
heterogenous mixture of chemicals and
other ingredients. Their exact formulation
depends upon the substrate through
which the drilling is taking place, depth of
the well, and particular functions of the
fluid required at a specific time.
Release of drilling fluids from drilling
platforms into the marine environment is
of concern because of their potential
adverse impacts on organisms and
alteration of substrates and other aspects
of the environment. Through the research
described herein, EPA has attempted to
provide scientific information on the fates
and effects of drilling fluids in the marine
environment.
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Methods
Research efforts for this project were
accomplished mainly through EPA Coop-
erative Agreements with academic
institutions and contracts with private
laboratories. The principal investigators
at participating institutions were encour-
aged to publish their results in peer-
reviewed journals or peer-reviewed EPA
reports available through the National
Technical Information Service (NTIS).
Investigators used a variety of drilling
fluids and various techniques in their
experiments; detailed information can be
found in the respective published papers
referenced herein.
Results
Some examples of results obtained
include the impact of drilling fluids on
various species of marine organisms.
Corals were studied by several investiga-
tors (Dodge, 1982; Szmant-Froelich et al.,
1982; Szmant-Froelich, 1983; Kendall et
al.. 1983; and Parker et al., 1984). Expo-
sure of Montastrea annularis to 100 parts
per million (ppm) of used drilling fluid
significantly reduced calcification and
respiration rates, gross photosynthesis,
nitrate uptake rate, and feeding response,
but exposure to 1 and 10 ppm of the same
fluid did not. However, Montastrea
annularis exposed to 1 ppm, 10 ppm, or
100 ppm of used drilling fluid showed
significant effects in three biochemical
measures—diacylphospholipids, plas-
malogen phospholipids and free amino
acids. Acropora cervicornis responded to
exposures of 25 ppm, 50 ppm, and 100
ppm with significant decreases in calcifi-
cation rate and soluble tissue protein
content in growing tips.
Conklin et al. (1983)andDoughtieetal.
(1983) tested the effects of samples of
used drilling fluids on molting grass
shrimp (Palaemonetes pugio}. Concen-
trations from 360 ppm to 14,500 ppm
caused 50 percent mortality in the test
within 96 hours (96-h LC50). There was a
high correlation between the presence of
diesel oil-like hydrocarbons in the drilling
fluid samples and toxicity, but a low cor-
relation between chromium content and
toxicity.
Derby and Atema (1981) and Capuzzo
and Derby (1982) conducted research on
the effects of used drilling fluids on
American lobsters (Homarus americanus).
Exposures of lobster legs to 10 ppm and
100 ppm for 3 to 5 minutes caused
diminished response to food odors by
29% and 44%, respectively. The 96-h
LC50's for five drilling fluids were from
74 ppm to 500 ppm, and sublethal
exposures resulted in alterations of
normal physiological functions, such as
growth and respiration rates.
Other experiments were conducted
with invertebrates by Schatten et al. (in
press) and Crawford and Gates (1983)
who studied sea urchins and sand
dollars. Lytechinus variegatusandArbacia
punctulata exposed to >1 millimolar
barium sulfate (233 ppm) exhibited
reduced fertilization processes, and 10
millimolar exposure halted all fertilization
and development. The development of
Echinarachnium parma embryos was not
adversely affectd by <100 ppm drilling
fluid, but 1 and 10 parts per thousand
(ppt) adversely affected fertilization and
subsequent embryo development.
Crawford and Gates (1981) also inves-
tigated the effects of used drilling fluids
on development of a fish, Fundulus
heteroclitus. Embryos placed in concen-
trations from 1 ppm to 10 ppt showed no
significant adverse effects during early
development but, by the seventh day of
exposure, various sublethal effects were
observed. The no-observable-effect con-
centration was 10 ppm.
The adverse effect of used drilling
muds containing diesel oil-like hydrocar-
bons on several species of marine
organisms was illustrated recently in a
research project coordinated by EPA's
Environmental Research Laboratory at
Gulf Breeze, Florida (ERL/GB). Eleven
mud samples, collected from operating
wells at various geographical locations
and depths in the Gulf of Mexico by the
Petroleum Equipment Suppliers Associa-
tion, were split into subsamples. Duplicate
samples were sent to the American
Petroleum Institute and retained at
ERL/GB where tests were conducted to
evaluate the effects of the liquid, suspended
particulate, and solid phases of each
drilling fluid and the whole fluid on
mysids (Mysidopsis bahia). In addition,
Conklin and Rao (University of West
Florida) evaluated the effects of the fluids
on grass shrimp (Palaemonetes interme-
dius); the New England Aquarium (NEA)
staff, hard clams (Mercenaria mercenaria);
Powell (Texas A&M University), corals
(Acropora cervicornis); and Crawford
(Trinity College), the mummichog (Fundu-
lus heteroclitus), sand dollars (Echinara-
chnius parma), and sea urchins (Strongy-
locentrotus purpuratus, Lytechinus pic-
tus, and L variegatus).
Chemical analyses of the 11 drilling
fluids were performed by Science Appli-
cations, Inc. (SAI) and by NEA. The SAI
group analyzed the fluids for barium,
aluminum, cadmium, chromium, copper,
and iron as well as for aromatic and
aliphatic fractions. The NEA staff analyzed
the fluids for barium, cadmium, chromium,
copper, manganese, lead, and zinc. The
two oxidation states of chromium, Cr*3
and Cr+6, were studied. Also, the NEA
group determined concentrations of
"diesel" in each of the drilling fluid
samples.
In summary, the toxicity of these 11
used muds to mysids, grass shrimp, hard
clams, and coral was greater (lower
LC50's) than previously reported for used
muds, with the exception of those from
Mobile Bay, Alabama. The LCSO's ranged
from 25 ppm to ^>1,500 ppm. Also, some
embryological research with mummichog
and several species of echinoderms
indicated that some of the muds signifi-
cantly inhibited embryological develop-
ment; one required a 105 dilution to reach
a "safe" concentration. An inspection of
the data reveals, with the exception of
corals, a relationship between the
"diesel" oil content and toxicity of the
muds. A Spearman Rank Order Correla-
tion Analysis (Steel and Torrie, 1980)
yielded significant (cr=0.05) correlation
coefficients between -0.74 and -0.96.
Subsequent results obtained by testing
the toxicity of drilling muds before and
after addition of API #2 fuel oil also
confirmed that addition of diesel increased
the toxicity of the muds tested.
The Adaptive Environmental Assess-
ment Method was used to synthesize
data on the impact of drilling fluids on the
marine environment and to prepare
dynamic simulation models to describe
the impact. The models were constructed
and refined by participants at two
workshops who agreed at the onset that
the models could serve as a tool for
evaluating the impact of drilling fluids on
the environment, but that they were
inappropriate as the sole basis for
environmental evaluations. The param-
eters used in the models, outputs from
various scenarios, and discussions of
applicability of the outputs are discussed
in the final project report and by Auble et
al. (1982).
Conclusions and
Recommendations
Results of research activities from this
and other projects show that drilling
fluids are toxic to marine organisms at
certain concentrations and exposure
regimes. Further, drilling fluids can
adversely affect animals—especially
benthos—through physical contact, by
burying, or by altering substrate composi-
tion. Drilling fluids also can exert effects
by disrupting essential physiological
functions of organisms.
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Much less information is available on
the environmental concentrations of
drilling fluids that result from discharges
into the marine environment than is
available on toxic effects. However,
available data and models suggest that
when discharges are made from platforms
located in open, well-mixed, and relatively
deep (>20 meters [m]) marine environ-
ments under the ranges of operating and
environmental conditions discussed in
the Adaptive Environmental Assessment
workshops, most detectable acute effects
will be limited to an area within several
hundred meters of the point of discharge.
Based on laboratory-derived effects data,
there will be sufficient dilution of the
drilling fluids in the water column (106
dilution within approximately 1,000 m of
the point of discharge) to minimize acute
effects on water column organisms
similar to those tested to date. Benthic
organisms within about 300 m of the
discharge will be potentially subject to
adverse effects caused by burial and
chemical toxicity; they may also be
susceptible to direct effects or substrate
changes for greater distances. Possible
exceptions to these generalizations could
occur when discharges are near sensitive
biological areas, such as coral reefs, or in
poorly flushed environments.
Laboratory toxicity tests indicated that
#2 fuel oil of known composition, "diesel-
like" hydrocarbons in used drilling fluids
from the Gulf of Mexico, and mineral oil
were correlated with toxicity — the
higher the hydrocarbon content, the
greater the toxicity. Tests showed that
when API #2 fuel oil (diesel) was added to
one of the used fluids with a low "diesel"
content, the treatment increased the
toxicity of the fluid to grass shrimp.
Similar results were obtained when
mineral oil was added to laboratory-
prepared generic drilling fluids; the
toxicity of fluid to mysids increased as the
concentration of mineral oil increased.
Experiments conducted with grass shrimp
indicated that when equal amounts of API
#2 fuel oil and mineral oil were added to a
hydrocarbon-free reference drilling fluid
prepared by the National Bureau of
Standard for use in the ERL/GB research
program, the fuel oil-treated preparation
was about three times more toxic than
the reference fluid with mineral oil added.
Additional tests are needed to compare
the toxicity of these two additives to other
organisms as are tests to determine their
no-observed-effect concentrations on
various species and communities. It
would also be useful to establish a data
base on the long-term toxicity of other
drilling fluid additives, including biocides.
More data on sublethal and chronic
effects should be developed to assess the
potential long-term toxicity of drilling
fluids to benthic communities. Such
studies should generate information on
the bioaccumulation of specific drilling
fluid components. Additional evaluations
of the toxicity of Cr+3 and Cr*6, and the
effects and bioavailability of other drilling
fluid components such as barite are also
needed. Additional research also is
needed to quantitatively address the limits
of applicability of the assumptions and
inputs of the fate models developed in the
AEA workshops in order to validate the
models. Special emphasis should be
placed on the evaluation of models of
discharges from multiple development
rigs because these are the sites of the
most intensive drilling fluid discharges.
The Adaptive Environmental Assess-
ment process appears to be a sound
approach in developing models to explain
the fate and effects of drilling fluids
discharged in the marine environment.
Development of the AEA models has
accentuated certain gaps in our know-
ledge and has emphasized the importance
of considering the potential magnitude of
the effects of natural episodic events and
the dynamics of marine ecosystems. The
rigor and general applicability of these
models in special cases where discharges
are close to shore in areas of high
productivity, or where discharges are
proximal to unique habitats, is not well
established. Along with a general effort to
validate the predictive capability of the
models, a special effort is needed to
determine how well these models address
special cases and other contingencies.
The need is particularly acute where
permit activities involve nearshore coastal
or estuarine environments.
In summary, it is possible through
existing data and empirical and numerical
models to estimate the impact of drilling
fluids on specific areas of the marine
environment, based on predicted envi-
ronmental concentrations and effects
(determined mainly in the laboratory) at
those concentrations. However, the
data base for the models should be
expanded by (a) monitoring existing and
proposed discharges for specific informa-
tion, and (b) conducting long-term tests at
environmentally realistic concentrations
to determine community and system
effects and chronic effects on organisms
representative of areas of biological
concern. At present, there is not sufficient
evidence that acute toxicity tests, even
under optimal conditions, reveal subtle,
adverse effects that could occur at the
ecosystem level of biological complexity
as the result of drilling fluid discharges.
Literature Cited
Auble, G.T., A.K. Andrews, R.A. Ellison,
D.B. Hamilton, R.A. Johnson, J.E.
Roelle, and D.R. Marmorek. 1982.
Results of an adaptive environmental
assessment modeling workshop con-
cerning potential impacts of drilling
muds and cuttings on the marine
environment. EPA-600/9-82-01 9,
Environmental Research Laboratory,
Gulf Breeze, FL 64 pp.
Cappuzzo, J.M. and J.G. Smith Derby.
1982. Drilling fluid effects to develop-
mental stages of the American Lobster.
EPA-600/4-82-039, Environmental
Research Laboratory, Gulf Breeze, FL.
52pp.
Conklin, P.J., D. Drysdale, D.G. Doughtie,
K.R. Rao, J.P. Kakareka, T.R. Gilbert,
and R.F. Shokes. 1983. Comparative
toxicity of drilling muds: Role of
chromium and petroleum hydrocar-
bons. Marine Environmental Research
J0(2):105-125.
Crawford, R.B. and J.D. Gates. 1981.
Effects of a drilling fluid on the
development of a teleost and an
echinoderm. Bulletin of Environmental
Contamination and Toxicology 26:207-
212.
Derby, C.D. and J. Atema. 1981. Influence
of drilling muds on the primary chemo-
sensory neurons in walking legs of the
lobster, Homarus americanus. Canadian
Journal of Fisheries and Aquatic
Sciences 38(3):268-274.
Dodge, R.E. 1982. Effects of drilling mud
on the reef-building coral Monstastrea
annularis. Marine Biology 71(2):141-
147.
Doughtie, D.G., P.J. Conklin, and K.R.
Rao. 1983. Cuticular lesions induced in
grass shrimp exposed to hexavalent
chromium. Journal of Invertebrate
Pathology 42(2):249-258.
Kendall, J.J., Jr., E.N. Powell, S.J. Connor
and T.J. Bright. 1983. The effects of
drilling fluids (muds) and turbidity on
the growth and metabolic state of the
coral Acropora cervicornis, with com-
ments on methods of normalization for
coral data. Bulletin of Marine Science
33(2):336-352.
Parker, J.H., J.S. Nickels, R.F. Martz, M.J.
Gehron, N.L. Richards, and D.C. White.
1984. Effect of oil and gas well-drilling
fluids on the physiological status and
microbial infection of the reef building
coral Montastrea annularis. Archives
of Environmental Contamination and
Toxicology 13(1):113-118.
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Schatten, G., D. Simerly, and H. Schatten.
In press. The effects of barium sulfate
on sea urchin fertilization and early
development. In: Wastes in the Sea,
Vol. 3. John Wiley and Sons, Inc., New
York.
Steel, R.G. and J.H. Torrie. 1980. Princi-
ples and Procedures of Statistics, 2nd
Ed. McGraw-Hill, New York. 633 pp.
Szmant-Froelich, A., V. Johnson, T.
Hoehn, J. Battey, G.J. Smith, E.
Fleischmann, J. Porter, and D. Dall-
meyer. 1982. Physiological effects of
oil-drilling muds on the Caribbean coral
Monastrea annularis. In: Reef and
Man: Proceedings of the Fourth Inter-
national Coral Reef Symposium, Manila.
E.D. Gomez et al., Editors. Pp. 163-168.
Szmant-Froelich A. 1983. Physiological
effects of drilling muds on reef corals.
EPA-600/3-83-013, Environmental
Research Laboratory, Gulf Breeze, FL
54 pp.
The EPA authors Thomas W. Duke and Patrick R. Parrish are with the
Environmental Research Laboratory. Gulf Breeze. FL 32561.
The complete report, entitled "Results of the Drilling Fluids Research Program
Sponsored by the Gulf Breeze Environmental Research Laboratory. 1976-1983,
and Their Application to Hazard Assessment, "(Order No. PB 84-223 072; Cost:
$ 17.50, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, v'A 22)'61
Telephone: 703-487-4650
The EPA authors can be contacted at:
Environmental Research Laboratory
U.S. Environmental Protection Agency
Sabine Island
Gulf Breeze, FL 32561
U.S. GOVERNMENT PRINTING OFFICE; 1984 — 759-015/7786
United States
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Agency
Center for Environmental Research
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Official Business
Penalty for Private Use $300
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