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United State* Science Advisory EPA-SAB-EPEC-92-O14
Environmental Board (A-101) January 1992
Protection Agency
AIM SAB REPORT: REVIEW
OF A TESTING MANUAL
FOR EVALUATION OF
DREDGED MATERIAL
PROPOSED FOR OCEAN
DISPOSAL
PREPARED BY THE SEDIMENT
CRITERIA SUBCOMMITTEE OF THE
ECOLOGICAL PROCESSES AND
EFFECTS COMMITTEE
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UNITED STATES ENVIRONMENTAL PROTECTION AGE\C
WASHINGTON DC 20-160
January 9, 1992
EPA-SAB-EPEC-92-014
The Honorable William Reilly
Administrator
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
RE: SAB Report "Review of a Testing Manual for Evaluation of
Dredged Material Proposed for Ocean Disposal"
Dear Mr. Reilly:
The Sediment Criteria Subcommittee of the Ecological Processes and Effects
Committee of the Science Advisory Board has completed its review of the draft
manual "Evaluation of Dredged Materials Proposed for Ocean Disposal - Testing
Manual". This manual, commonly referred to as the "Green Book", is an update of
the 1977 version. It provides National technical guidance for use in establishing
the Limiting Permissible Concentration (LPC) for ocean disposal of dredged
material. The manual uses a tiered approach, which the Agency's Contaminated
Sediment Strategy Task Force is also considering for use in other programs.
The Subcommittee was asked by the Office of Water to review a portion of
the 1991 Green Book to assess the adequacy of the bioaccumulation and toxicity
testing procedures in the manual and to identify other methods which could
address chronic toxicity and bioaccumulation. The Subcommittee met on April 15-
16, 1991 and again on September 24, 1991 to complete the review.
The Subcommittee found that the revised manual is a significant
improvement over the preexisting 1977 "Green Book", with respect to the use of
the reference sediments, the selection of test organisms, and the option of using a
28-day bioaccumulation study. There are, however, several changes which should
be made now, including those which: identify which tests and test organisms are
mandatory; standardize definitions of endpoints and stressors; and provide an
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interpretative framework for decisions at the local Corps of Engineers and EPA
offices. On a somewhat longer time scale, the Subcommittee recommends that
EPA make additional changes to: focus the tiered evaluation process in the
manual toward reducing uncertainty, develop guidelines to interpret
bioaccumulation tests, conduct studies of the relationship of body burdens to "no
observed effect levels", update the concept of an application factor, and define how
sediment quality criteria will apply to the "Green Book".
The Sediment Criteria Subcommittee has been asked by the Office of Water
to conduct another review of the technical guidance needs for disposal of dredged
materials at inland sites that are covered under the Clean Water Act. Several of
the recommendations from this review should also be considered by EPA in the
development of this second guidance.
We look forward to receiving your response to our recommendations and we
are particularly interested in any plans that the Agency may have to further its
understanding of the evaluation and interpretation of bioaccumulation of
substances from sediments and the use of application factors. We look forward to
advising you in the future on these and other issues related to contaminated
sediments.
Sincerely yours,
Raymond Loehr, PhD.
Chair
Science Advisory Board
Kenneth L. Dickson, PhD.
Chair
Ecological Processes and
Effects Committee
E, PhD.
Chair
Sediment Criteria Subcommittee
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NOTICE
This report has been written as a part of the activities of the Science
Advisory Board, a public advisory group providing extramural scientific
information and advice to the Administrator and other officials of the Environ-
mental Protection Agency. The Board is structured to provide a balanced expert
assessment of scientific matters related to problems facing the Agency. This
report has not been" reviewed for approval by the Agency, and, hence, the contents
of this report does not necessarily represent the views and policies of the
Environmental Protection Agency or other Agencies in Federal Government.
Mention of trade names or commercial products do not constitute a recommen-
dation for use.
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US. ENVIRONMENTAL PROTECTION AGENCY
SCIENCE ADVISORY BOARD
ECOLOGICAL PROCESSES AND EFFECTS COMMITTEE
SEDIMENT CRITERIA SUBCOMMITTEE
ROSTER
CHAIRMAN
Dr. Robert Huggett, Virginia Institute of Marine Science, School of Marine Sciences,
College of William and Mary, Gloucester, Virginia
MEMBERS
Dr. William Adams, ABC Laboratories, Columbia, Missouri
Dr. Donald F. Boesch, Director, Center for Environmental and Estuarine Studies
System, University of Maryland, Cambridge, Maryland
Dr. Peter Chapman, E.V.S. Consultants, Vancouver, British Columbia, Canada
Dr. Rolf Hartung, School of Public Health, University of Michigan, Ann Arbor,
Michigan
Dr. Frederick K. Pfaender, Department of Environmental Sciences and Engineering,
University of North Carolina, Chapel Hill, North Carolina
FEDERAL AGENCY LIAISONS
Dr. Robert Scott Carr, NFCR Field Research Station, US FWS, Corpus Christi,
Texas
Dr. Suzanne Bricker, NOAA, Rockville, Maryland
SCIENCE ADVISORY STAFF
Dr. Edward S. Bender, Biologist and Designated Federal Official
Ms. Marcia K. Jolly, Staff Secretary
Mr. Robert Flaak, Asistant Staff Director
Dr. Donald G. Barnes, Staff Director
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ABSTRACT
This report represents the findings and recommendations of the U.S. Environmen-
tal Protection Agency's Science Advisory Board summarizing a review of the
"Evaluation of Dredged Materials for Ocean Disposal-Testing Manual". The review
was conducted by the Sediment Criteria Subcommittee at two meetings on April 16-
17 and September 24, 1991. The manual outlines a tiered testing approach for
evaluating dredged materials for compliance with the limiting permissible concentra-
tion (LPC) as defined by the Ocean Dumping Regulations. The Subcommittee
reviewed the adequacy of the bioaccumulation and toxicity testing procedures in the
manual and provided recommendations for mandatory tests, selection of test
organisms, and the development of a regulatory framework for interpreting the
results. The Subcommittee also recommended that EPA revise the guidance to
clarify the use of the tiered approach, to elaborate the requirements for evaluation
under tier IV of the scheme, define the relationship of Sediment Quality Criteria to
the "Green Book", expand guidance on the selection of reference sites, and to
address several scientific questions about bioaccumulation and its effects on the
organism. The Subcommittee further recommended several editorial changes for
clarity and consistency of the definitions, eliminating redundancies, and consolidat-
ing the quality assurance requirements for the test results.
Kev Words: Dredged Materials; Bioaccumulation Potential, Toxicity; Tier testing.
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TABLE OF CONTENTS
1.0 EXECUTIVE SUMMARY 1
2.0 INTRODUCTION 2
2.1 Statement of the Charge 2
2.2 Subcommittee Review Procedures 3
3.0 EVALUATION OF THE BIOASSAY AND BIOACCUMULATION
METHODS FOR DREDGED MATERIALS 4
3.1 General Comments 4
3.1.1 Tiered Testing 4
3.1.2 Microbiological Concerns 5
3.1.3 Quality Assurance and Quality Control 5
3.1.4 Definitions 6
3.1.5 Synergistic Effects 6
3.1.6 Use of Sediment Quality Criteria 7
3.1.7 Redundancy 7
3.2 Selection of Organisms used in Bioassays 7
3.2.1 Recommended Species List 7
3.2.2 Criteria for species selection 8
3.2.3 Bioaccumulation Tests 8
3,2.4 Development of Tests 8
3.2.5 Mandatory Tests 8
3.3 Bioassays and Endpoints 9
3.3.1 Water Column Concentrations 9
3.3.2 Application Factor 10
3.3.2 Theoretical Bioaccumulation Potential 12
3.3.3 Rationale for Bioaccumulation Tests 13
3.3.5 Toxicity Test Endpoints 14
3.4 Reference Area Concept 15
3.5 Interpretative Guidance 15
3.6 Tier IV Requirements 16
4.0 SUMMARY OF RECOMMENDATIONS 17
5.0 LITERATURE CITED 19
IV
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1.0 EXECUTIVE SUMMARY
The Sediment Criteria Subcommittee met twice April 16-17 and September
24, 1991, to review the bioassays and bioaccumulation test procedures that were
used in the draft manual entitled, "Evaluation of Dredged Materials for Proposed
Ocean Disposal-Testing Manual (February, 1991)". This manual is referred to as
the "Green Book" and represents an update of a 1977 version. Both manuals were
developed jointly by the Corps of Engineers and EPA. The Subcommittee was
asked to evaluate the adequacy of the bioaccumulation and toxicity test procedures
in the revised manual for assessing contamination of sediments in the National
Ocean Disposal Program.
The Subcommittee found that the revised manual represented a significant
improvement over the 1977 version with regard to the use of the reference
sediments, the selection of test organisms, and the option of using a 28-day
bioaccumulation study. In its deliberations, the Subcommittee found that this
manual addressed several principles that had significant implications for the
evaluation of dredged materials for disposal in freshwater as well as for managing
contaminated sediments in other situations. However, the Subcommittee believed
that the manual could benefit from careful editing and further refinement of the
tiered approach.
There were several changes, which the Subcommittee has recommended, that
should be made now, including those which: specify which tests and test organisms
are mandatory; standardize definitions of endpoints and stressors; and provide an
interpretative framework for decisions at the local Corps of Engineers and EPA
offices.
On a somewhat longer time scale, the Subcommittee recommends that EPA
focus the tiered evaluation process toward reducing uncertainty, develop guidelines
to interpret the results of bioaccumulation tests, conduct studies of the relationship
of body burdens to "no observed effect levels", and re-evaluate and modify, if
necessary the concept of a constant application factor. The tiered approach should
also be revised to allow the reevaluation at higher tiers for sediments that failed at
a lower tier. The manual should be revised to address microbiological issues or
renamed and provide the reader with other sources or references for test
procedures to address these issues. Guidance on quality assurance should be
consolidated and a glossary of terms should be added and used in a consistent
fashion throughout the document. The Subcommittee recommended that EPA
define the relationship between the "Green Book" and Sediment Quality Criteria.
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2.0 INTRODUCTION
The maintenance of navigation channels requires dredging. The disposal of
that dredged material is a concern to government, industry, and public sectors.
For ocean disposal, the dredged material must be evaluated to determine its impact
adjacent to the disposal site. In 1977, EPA and the Army Corps of Engineers
(COE) developed a manual "Ecological Evaluation of Proposed Discharge of Dredged
Material into Ocean Waters" which contains technical guidance on chemical,
physical, and biological procedures to determine the acceptability of dredged
material for ocean disposal. In February 1991, the EPA and COE published a
revised draft of this manual, commonly called "the Green Book" that included more
testing procedures. This manual will be updated in the future in accordance with
revised rules for Ocean Dumping.
The manual outlines what is called a tiered testing procedure for evaluating
compliance with the limiting permissible concentration (LPC) for long term
exposures that are defined by the ocean dumping regulations. The liquid phase or
water column LPC must not exceed applicable marine water quality criteria or a
toxicity threshold (0.01, an application factor, times the acutely toxic concentration).
The suspended and solid phase LPCs must not cause unreasonable toxicity or
bioaccumulation. The manual describes four levels (tiers) of evaluations. Tiers I
and II utilize existing information, which is often available for recurring disposals
of dredged materials from channel maintenance to determine the appropriateness of
ocean disposal. Tier III contains most of the laboratory bioassays, and Tier IV
includes some tests of bioaccumulation and a range of possible field investigations.
The manual also recommends use of a reference site, which is intended to be free
from contamination, as source of sediments for comparison testing with the dredged
materials.
2.1 Statement of the Charge
On March 6, 1991, the Office of Marine and Estuarine Protection requested
that the SAB review the toxicity testing and bioaccumulation methods of the "Green
Book". As part of that review the Subcommittee was asked to address the following
question:
Are the bioassays, (bioaccumulation, chronic/sublethal, and acute toxicity
tests) currently in use or under development by EPA and the Corps of
Engineers, appropriate for assessing contamination of sediments for use in
the National Ocean Disposal Program? How can they be improved?
The Subcommittee accepted the charge but noted that it was also necessary
to review the bioassays in the context in which they would be applied. In
particular, the Subcommittee felt the review must include some aspects of the tiered
approach and the use of a reference site to evaluate some of the bioassay results.
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2.2 Subcommittee Review Procedures
The Sediment Criteria Subcommittee, a standing group of the Ecological
Processes and Effects Committee of the SAB, was established to review and
evaluate methods and procedures for assessing the quality of sediments. The
membership of the Subcommittee has changed to provide expertise that is needed
for specific reviews, however, the Chairman and a small nucleus of experienced
members have been retained to provide consistency. For this review, the
Subcommittee relied on background materials and briefings on the manual and the
development of methods of testing acute and chronic toxicity.
The Subcommittee met twice to review the Dredged Materials guidance, first
on April 16-17, 1991 and again on September 24, 1991 in public meetings. Between
the two meetings, draft comments were prepared and EPA reconsidered the charge
for the Subcommittee as discussed in section 2.1. The Subcommittee expects to
address broader aspects of sediment control strategies in another review in 1992.
During the September meeting, the Subcommittee was also advised of additional
guidance that EPA and the Corps of Engineers are developing for disposal of
dredged materials in freshwater and estuarine sites under the jurisdiction of the
Clean Water Act. Following the public meeting, the Subcommittee held a writing
session prepare the revise the draft report.
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3.0 EVALUATION OF THE BIOASSAY AND BIOACCUMULATION
METHODS FOR DREDGED MATERIALS
3.1 General Comments
The document represents an improvement over the preexisting 1977 "Green
Book". It includes a hierarchial testing approach with emphasis on the use of
aquatic toxicity tests and it provides better guidance on species selection and use of
reference material. It also provides the option of using a 28-day bioaccumulation
study. The approach, although not incorporating a true tiered approach, should
help eliminate unnecessary testing as well as identify those sediments that should
be tested further.
The emphasis of the man"*! is clearly on toxicity and bioaccumulation test
methods, with brief coverage of physical and chemical characterization of sediments
and dredged materials. Microbiological issues, introduction of new species,
genotoxicity testing, etc., are not covered. If EPA wishes to maintain the manual's
focus on toxicity and bioaccumulation testing, it should consider renaming the
document to better describe its contents or include a section in future drafts
identifying all the testing required by the legislation and directing the user to other
documents that contain testing procedures for parameters not covered by this
document.
3.1.1 Tiered Testing
The Subcommittee supports the concept of tiers, best professional judgement,
site-specific information, expertise and judgement calls. However, the framework
for their use and the limitations to such use must be clearly enunciated.
Conceptually, increasing tiers should correspond to decreasing uncertainty. This is
not the case in the present document. Tier III appears always to be required.
Additive effects are always expected to occur and are the basis of EPA's own risk
assessment guidelines for mixtures (U.S. EPA, 1982). Synergism, if defined as a
greater than additive response, cannot be predicted for complex mixtures. It is to
be expected in an unknown proportion of cases and can only be established by
determining the toxicities of all of the ingredients of the mixture compared to the
toxicity of the mixture itself (Hartung, 1988; Stara & Erdreich, 1985; N.R.C., 1988).
Consequently Tier III, as presently defined, will always be required. Also, there is
no connection between Tiers III and IV. If applicants fail Tier III, there is no
alternative to prove that the sediment is acceptable and, similarly, regulators also
have no mechanism to require further testing if sediments pass Tier III.
Most tiered assessment systems are designed so that the lower and more
simplistic tiers embody more conservative assumptions than do the higher tiers.
This is the correct strategy, because the minimal information requirements in the
lower tiers yield a broader range of uncertainties than the more extensive
information requirements in higher tiers, However, this strategy produces the
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ramification that some dredged materials that would fail a lower tier, could pass
when tested in a higher tier. Unless the criteria for passing the higher tier
requirements are fatally flawed, such a dredged material should be perfectly
suitable for disposal. However, in the present strategy a material that fails at any
tier is not eligible for more detailed evaluation at a higher tier. Further, the
document clearly states that applicants can skip tiers. True tiered testing does not
have superfluous tiers and does not allow entry at any point. True tiered testing
allows for flexibility to challenge the assumptions and preliminary results at lower
tiers; the present "tiers" minimize flexibility. The Subcommittee recommends that
EPA revise its tiered approach to allow revaluation at higher tiers of failures at
lower tiers, to clarify the linkages between tiers, and to emphasize reducing
uncertainly as the level of tier testing increases.
3.L2 Microbiological Concerns
Sections 227.7(c)l, 228,10.6 and perhaps other portions of the revised rules
for Ocean Dumping deal with the relocation of materials containing pathogenic
microorganism, including viruses. This may be a very real issue, both in instances
where sewage- contaminated materials are being dredged, especially if they are
deposited on beaches, and for those human pathogens indigenous to the marine
environment, i.e. Vibrio parahaemolyticus and Vibrio vulnificans. The testing
manual contains no guidance on how dredged materials, control and reference sites
should be evaluated for this class of biological contaminants. EPA's response to
this issue seems to be that the manual under review deals with chemical toxicity
and bioaccumulation testing and therefore microorganisms were not included. Since
pathogenic microorganisms of fecal origin are usually present in environmental
samples at concentrations too low to be directly detected by routinely available
methods, we use bioassays of indicator organisms to provide evidence of their
presence and the potential for human disease. Many different indicator organisms
and testing approaches are available, ranging from the traditional coliform bacteria
and fecal streptococci to more recent suggestions of bacteriophage and enteric
viruses. The strengths and weaknesses of each have been extensively reviewed and
discussed. The fact that there are significant problems in the application of some
of these indicators and detection approaches in marine waters suggests that
guidance is needed in a document that emphasizes bioassay testing methods. At a
minimum the topic should be mentioned and the user directed to pertinent
documents, many generated by EPA such as the National Estuary Program
Monitoring Guidance Document, APHA Standard Methods for the Examination of
Water and Wastewater, and EPA's methods published under Section 304.602 of the
Clean Water Act that contain appropriate guidance and methods.
3.1.3 Quality Assurance and Quality Control
All quality assurance/quality control discussion should be consolidated in one
section. Throughout the manual there is a great deal of redundancy regarding
QA/QC and there is some incorrect information. For example, 24-h reference
toxicant tests are recommended for amphipods, whereas 96-h testing is the correct
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requirement. The Subcommittee recommends that QA/QC be a separate, detailed
Section, and that testing protocols be appropriate and clearly specified.
Method Detection Limits should be provided for all chemicals in all media; in
certain cases, there could be ranges rather than a single value. In either case,
guidance is required and could be provided with a table showing how much tissue
is required to achieve what detection limits by what analysis. This information
would provide guidance for a priori selection of species and methods.
3.1.4 Definitions
Definitions are not always provided for critical terms used in the document,
including: chronic, sublethal, sublethal chronic. The definition of bioaccumulation
needs to be consistently applied throughout. The definition of LPC uses the
wording "unreasonable toxicity", which should be defined. Three separate terms are
defined under "may": may, can and might. These terms should be defined
separately so the reader can find them. The terms "as similar as practicable" and
"to the maximum extent possible" under Reference Sediment should be clarified.
Preparation of Whole Sediment allows press-sieving and the "additions of small
amounts of seawater"; the latter is of concern regarding dilution of the chemicals
and the modification of their toxicity and no documentation is provided to support
the statement "These procedures are unlikely to substantially alter chemical or
toxicological properties of the respective whole sediments." "Pollution" as used on
page 2-7, line 3 of paragraph 1 should also be defined. The document contains
many abbreviations (e.g., LPC, LBP, TBP, MDL, etc.), but it does not contain a list
of abbreviations used for reference purposes.
The Subcommittee recommends that a Glossary of Terms be generated and
that the terms, as defined, be used in a consistent manner throughout the
document.
3.1.5 Synergistic Effects
On pages 2-5, 2-6 and 3-11 the use of the words "synergistic effects" does not
accurately reflect the state-of-the-art for aquatic toxicological tests. The draft
document requires that the LPC be 0.01 of the acute toxicity when there are no
water quality criteria or when the chemicals present are suspected of producing
"synergistic effects". Years of acute toxicity testing and to a lesser extent chronic
toxicity tests with aquatic organisms for a wide variety of test chemicals have
indicated that synergistic effects are very rare. Most chemicals when tested in
combination show additive effects or in some cases antagonistic effects. The
manner in which the phrase "synergistic effects" is used in the document is either
inappropriate or the authors meant "additivity".
The treatment of the toxicity of mixtures in the document does not take full
advantage of the existing scientific literature. The NAS/NRC, U.S. EPA, and others
have published reviews on the toxicity of mixtures which lend support to the
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hypothesis that the acute toxicity of a mixture is, on the average, predicted by the
sum of the acute toxicities of the components in the mixture. Thus, additive
toxicity is the expected outcome, although greater than expected toxicities (variously
defined as supra-additive, synergism, potentiation), as well as less-than expected
toxicities (antagonism or infra-additive), have also been observed experimentally.
3.1.6 Use of Sediment Quality Criteria
EPA is in the process of developing guidance for the development and
application of sediment quality criteria (SQC) based on equilibrium partitioning.
The approach being used for non-ionic chemicals is to compare the interstitial water
concentration (based on the organic carbon normalized whole sediment chemical
concentrations and partitioning between the organic carbon and interstitial water)
with existing water quality criteria. This methodology has been reviewed by the
SAB ("Evaluation of the Equilibrium Partitioning (EqP) Approach for Assessing
Sediment Quality" EPA-SAB-EPEC-90-006, February, 1990) and the reader is
referred to this document for an evaluation of its strengths and weaknesses. Since
it is not clear how SQC will be utilized in the disposal of dredged materials, the
Subcommittee recommends that the applicability of sediment quality criteria to
dredged materials be delineated in the new "Green Book" Guidance.
3.1.7 Redundancy
The Manual is repetitive in places, especially in the first seven Sections. In
addition, there is a marked contrast in the level of guidance provided by equally
important sections. The Subcommittee recommends elimination of redundancies
and repetition such that important information is clear and not obscured.
3.2 Selection of Organisms used in Bioassays
3.2.1 Recommended Species List
Consistent with the objectives of the regulations, it is important that
"appropriate sensitive" organisms be selected both for water-column and sediment
bioassays. It should be understood that not all species deemed appropriate based
on the criteria listed in Section 11.1.1 are necessarily sensitive and that the range
of sensitivity of within a listed species is highly variable. Thus, it would be entirely
possible to select test species of very low sensitivity and maximize the potential for
passing the tests. However, it is also recognized that there are valid reasons to
select species which are economically or ecologically important in the receiving
waters, either to allay public concerns or to assess potential ecological effects in the
field. It is important to include bioassays of species known to be highly sensitive to
toxic effects of dredged material elutriates, including those designated by an
asterisk in Table 11-1, sea urchin larvae to the veliger stage and bivalve larvae to
the prossidonch stage. Additional bioassays of economically or ecologically
important species which may not be highly sensitive may also be included, but
should, to the extent practical, be based on the most sensitive life history stages of
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these species. The use of sensitive species mentioned above will lessen the need for
an application factor of 0.01 of the LC50 (Figure 3-2, page 3-9).
The Subcommittee recommends that Table 11-1 be amended such so that at
least one species with an asterisk must be tested and adult bivalves should be
removed from this list The option of testing with sand dollar larvae should also be
included. Further, larval tests should be clearly defined as involving development
of the fertilized egg to the prossidonch I (bivalve) or veliger (echinoderm) stage.
3.SL2 Criteria for species selection
There must be a clear and consistent rationale and explanation for the
species selection decisions. For instance, the argument for using zooplankton
rather than phytoplankton (Page 2-8, second line of first paragraph) is that the
latter are extremely variable. Zooplankton are also naturally very variable and in
many cases populations increase and collapse in direct response to changes in
phytoplankton populations. There are other cogent reasons for using zooplankton,
including techniques available, sensitivity, use as indicators, etc., and these should
be clearly stated.
3.2.3 Bioaccumulation Tests
The list of appropriate test species for bioaccumulation testing is provided in
Table 12-1 and includes both organisms in intimate contact with the sediment and
some that are not. The Subcommittee recommends that Table 12-1 be amended
such that recommended species be those in intimate contact with the sediments or
those that ingest sediments.
3.2.4 Development of Tests
The Army Corps of Engineers has devoted a considerable research effort to
developing a "chronic" toxicity test with the polychaete Neanthes arenaceodentata
for testing in Tier IV. However, evidence to date indicates that the Neanthes
arenaceodentata 20-day growth and survival test is no more sensitive than acute
lethality tests with infaunal amphipods. Since the purpose in recommending
chronic tests in Tier IV is apparently to achieve increased sensitivity, it would
appear that other test methods and test species other than Neanthes
arenaceodentata may be better suited for this task. Accordingly, the Subcommittee
questions whether the effort and emphasis on the Neanthes arenaceodentata
"chronic" test is warranted. We do not question a general emphasis on polychaetes
and amphipods for test development, as long as the tests are appropriately sensitive
and useful.
3.2.5 Mandatory Tests
The Subcommittee agrees with the current emphasis on acute toxicity,
specifically the limitation to mortality, and with the addition of the amphipod
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toxicity test. However, at present, the amphipod test is a recommendation, not a
requirement.
There are several specific requirements in the Ocean Dumping Regulations
(Title 40, Code of Federal Regulations, Part 220-228) which have not been
adequately addressed in the green book testing guidance. In Subpart G 227.27 (b),
the regulations state 'The limiting permissible concentration of the suspended
particulate and solid phases of a material means that concentration which will not
cause unreasonable acute or chronic toxicity or other sublethal adverse effects based
on bioassay results using appropriate sensitive marine organisms." The guidance in
the new green book does not provide recommendations for determining either
chronic or sublethal 'effects in solid-phase toxicity tests.
Some species of infaunal amphipods are considerably more sensitive than the
other "appropriate test species" endorsed for use in solid-phase tests in the new
green book. Although we recognize that there is no single bioassay organism which
is universally applicable for testing aquatic sediments, the guidance in the new
manual could permit an applicant to essentially insure that no significant toxicity
would occur by selecting the more insensitive "appropriate test species". The
Subcommittee recommends that the inclusion of a sensitive infimnal amphipod or
preferable an appropriately sensitive test incorporating measures of chronic
sublethal effects, as stated in the Ocean Dumping Regulations, be required in Tier
m.
The tests and test species recommended for solid-phase testing are not nearly
as sensitive as those recommended for water-column testing and there is no "safety"
factor or other means of providing a margin-of-error in the interpretation of the
toxicity data from solid-phase tests. In addition, the reference sediment, which is
collected from the vicinity of the disposal site, may be contaminated from previous
disposal operations or by its proximity to other anthropogenic inputs and therefore
serves to increase the probability of contaminated material being judged suitable for
ocean disposal.
3.3 Bioaasays and Endpoints
3.3.1 Water Column Concentrations
Page 5-2 of the document indicates that "step 1 of the tier II water column
evaluation comprises a screen that assumes that all of the contaminants in the
dredged material are released into the water column during the disposal operation."
If this results in a concentration in the water column that exceeds a water quality
criterion, then a leachate test is performed to better estimate the actual water
column concentration. Scientific knowledge regarding the bioavailability of
chemicals sorbed to sediments indicates that the presence of sediment reduces the
bioavailability of chemicals as compared to aqueous exposure without the presence
of sediment. Therefore, the above assumption is a very worst case and most often
unrealistic. The results of the elutriate tests should provide a large data base to
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draw from which would indicate the extent to which the bioavailability is reduced.
These data could be used to provide a more accurate assumption for step 1 of the
tier II water column evaluation.
3.3.2 Application Factor
The application factor is defined as:
AF = ["Safe" concentration]/[96hr. LC50 concentration]
Application factors were proposed as early as 1957 by Henderson to estimate
"safe" concentrations for compounds for which no chronic toxicity data were
available (NAS, 1972). It was recognized from the beginning that the AF was not a
constant, but that it varied for different substances and species. The use of generic
AF values for estimating "safe" concentrations, when only acute toxicity data were
known, was proposed by the NAS/NAE Committee on Water Quality Criteria (NAS,
1972). This publication used "...present knowledge, experience and judgement..." to
determine two classes of toxic compounds, for which different application factors
were applied (page 121 of the document):
1. non-persistent (half-life <4d) or non-cumulative chemicals were
considered "safe" at the following concentrations:
0.1 X 96-h LC50 at any time or place
0.05 X 96-h LC50 for a 24-h average
2. persistent, accumulative chemicals were considered "safe" at the
following concentrations:
0.05 X 96-h LC50 at any time or place
0.01 X 96-h LC50 for a 24-h average.
Specific wording of the recommendation is provided on page 269 of the document:
In general, marine life with the exception of fish-eating birds and
mammals should be protected where the maximum concentrations of the
chemical in the water does not exceed one-hundredth (0.01) of the LC50
values listed in Column 7, table 10-7, pp. 265-268. This factor is
arbitrary and was derived from data available on marine life and
freshwater organisms (See Section III, p. 121). It assumes that a
concentration of one-hundredth (0.01) of that causing harm to the most
sensitive species to be protected will not damage this species or the
ecosystem. Future studies may show that the application factor must be
decreased or increased in magnitude.
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Where data were available, this document recommended specific application
factors for the following chemicals, derived by dividing the "safe" concentration by
the 96-h LC50:
Freshwater Application Factors
PAEs, Cu - 0.1
Cyanides, detergents, phenolics - 0.05
Marine Water Application Factors
Fluorides, cyanides, ammonia, chlorine, boron, sulfide -0.1
Ag, Ba, Mo, Tl, Va - 0.05
Ni, Mn;Pb -0.02
Al, Cu, As, Cr, phosphorous, Se, Cd, Be, Zn, uranium - 0.01
Clearly, the 0.01 application factor was a "worst case" estimate made almost
two decades ago in the expectation that future research would result in refinement
of values for specific chemicals. Some refinement was even provided in the
document. Instead, the 0.01 value has become dogma. For instance, page 10 of the
1985 Technical Support Document for Water Quality-Based Toxics Control
(September 1985, 74pp + appendices) notes:
State standards often include the application factors (to derive a "safe"
toxicity value from an* acute toxicity value) that were recommended in
the 1972 "Blue Book" guidance (i.e., 0.05 for nonpersistent wastes and
0.01 for persistent wastes).
A variant of this approach is used in the development of present water
quality criteria, which employ the acute to chronic ratio (ACR) to estimate chronic
concentrations from acute toxicity data. The ACR is not a generic value, but is
calculated for each chemical on the basis of bioassay data.
The new "Green Book" (page 11-9, Section 11.1.7) refers to the LPC as being
"...0.01 of the 48- or 96-h LC50, depending on the test duration." This is a very
conservative estimate that assumes persistent chemicals are present; if
nonpersistent contaminants are present, this application factor may be too
stringent, particularly if truly sensitive test species are used, as we recommend.
Further, this application factor was intended to apply to acute toxicity data (e.g., it
does not apply to bivalve EC50 data).
Clearly, specific rather than generic application factors are justified by the
original [19 year old] source document. The Subcommittee recommends that EPA
produce a peer-reviewed report that provides direction on the application factor
issue appropriate for the 1990s and that the mamml clearly indicate that the 0.01
application factor is only potentially appropriate for LC50 data with persistent
chemicals.
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3.3.2 Theoretical Bioaccumulation Potential
The degree of bioaccumulation is considered to be unacceptable if animals
exposed to dredged material bioaccumulate statistically greater amounts of
contaminants than do animals exposed to reference sediments (page 2-3). This goal
statement is reiterated in different words in section 5.2 (pages 5-5 to 6). The
sections of the act are referenced, but the pertinent points of the act are not
highlighted. The acceptability of the bioaccumulation is to be judged by the
Theoretical Bioaccumulation Potential (TBP).
The basic formula that is proposed for calculating the Theoretical
Bioaccumulation Potential (TBP) is:
TBP = 4 (Cg/%TOC)%L
This simplistic relationship seeks to summarize the differences in the
partitioning characteristics of sedimentary total organic carbon (TOO) and the total
lipids present in the biota compared with the concentration in the reference
sediment (Cs). The derivation of the proportionality factor of "4" encompasses
many kinds of variability which become important in the assessment. The
Committee recommends that the derivation of the factor "4" be documented to
include the variance associated with this point estimate.
The assessment of the Theoretical Bioaccumulation Potential is largely
dependent upon the comparative statistical distributions of the non-polar
contaminants in the dredged material and at the reference site. Both the
concentrations in reference sediments and dredged materials are expected to vary,
and of course the concentrations of contaminants and total organic carbon
concentrations are expected to co-vary. The overall null-hypothesis is that reference
sediments are not significantly different from dredged materials. The rigor of this
assessment is dependent upon the choice of the reference site and the adequacy of
the sampling of the reference site and the dredge materials in relation to the
occurrence of a and P errors in hypothesis testing. These complex relationships are
not clearly stated in the manual. It is possible to discern some of these problems
by careful analysis of topics that are widely dispersed in the manual.
At present, the extent of bioaccumulation is judged with respect to
compliance with FDA guidelines and with respect to significant differences from
reference sites.~In the absence of FDA guidelines the judgment criteria can
generate ambivalent results if the reference site is also contaminated. When the
concentration of contaminants in the dredged materials exceeds the concentration
found in the reference sediments, then the present methodology forces a decision
that there is a problem, regardless of whether there is an effect that is discernible
in biological studies. The manual indicates (pages 2-4 and 6-4) that a statistically
significant increase in chemical concentrations in the tissue of organisms exposed to
dredged materials as compared to organisms exposed to reference sediments is
interpreted as a specific biological effect and has the potential to cause ecologically
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unacceptable impact. The Subcommittee points out that statistically significant
increases in tissue concentrations do not constitute biologic effects per se. The
current guidance on bioaccumulation is driven by existing statutes. It is
recommended that appropriate consensus guidelines be drafted for interpretation of
bioaccumulation tests and that these guidelines be incorporated into the regulatory
framework. It is further recommended that the Agency conduct studies that relate
body burdens to "no observed effect levels" (NOEO as part of chronic toxicity
protocols.
As an adjunct to using the FDA guidelines, the Agency should routinely
measure the concentrations of test materials in the test organisms at the
termination of selected long-term toxicity studies. The important endpoint is the
body burden of the chemical found at the "No Observed Effect Concentration"
(NOEC). In long-term toxicity studies (on the order of months) the test organism
should have achieved a practical bioconcentration equilibrium with the test
substance, so that the concentration of the substance in the organism at the NOEC
could be used just as an FDA guideline level. In the case of organic substances it
may be useful to normalize the concentrations to the percent lipids in the organism.
There is some evidence that the effective concentrations of specific chemicals at
target sites are comparable over a wide range of species.
3.3.3 Rationale for Bioaccumulation Tests
The major concern over bioaccumulation is the build-up of toxicants in the
food chain and, ultimately, human health risk. Thus, the major reason for this
relatively expensive testing is to protect against biomagnification. But very few
chemicals have been shown to biomagnify. Moreover, biomagnification is usually
restricted to air breathing vertebrates (e.g., mink, heron, gulls, raptors, and seals).
Finally, there are no good endpoints for bioaccumulation testing at this time.
The blanket recommendation on the duration of 10 or 28 days for the uptake
studies is not appropriate. The basic problem with a 10-28 day bioconcentration
test is that the bioconcentration coefficient is defined as the ratio of the
concentration found in the exposed organism as related to the concentration of the
contaminant in water, determined at equilibrium. There is no assurance that the
exposed organism has achieved equilibrium at the end of 10 of 28 days. This
problem cannot be solved by inspection of the data, but can only be solved by
applying pharmacokinetic modeling to the test data (Spacie & Hamelink, 1985).
However, if bioaccumulation testing is necessary at lower tiers due to regulations (it
is not clear that this is, in fact, the case), then the 28-d test is a reasonable
compromise at present between over stressing organisms and getting a clear signal.
Still, it is important to note that steady state is not reached in all cases and the
accumulation factor of 4, based on PCB's, does not provide any additional
information. The range of mean application factor can be up to 20X different as
was apparent from presentations to the Committee from the COE. Further, the
statement that mortality of up to 25% in 28-d tests is acceptable (page 13-33,
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narrative line 14) is confusing given previous, apparently conflicting guidance on
acceptable mortality in these tests.
The suggested duration of exposure is clearly judgmental and arbitrary.
However, all of the evidence that has been uncovered to date supports the fact that
bioaccumulation in aquatic organisms follows a subset of the same rules that govern
the discipline of pharmacokinetics. Additional confounding factors for poikilotherms
and long durations of exposure are 1.- the influence of temperature on uptake and
clearance rate constants, and 2.- the influence of growth during prolonged
exposures. Regardless of these factors, the time to approximate equilibrium
concentration is governed by an inverse exponential function of the clearance
excretion rate constant K in the form of F(l-e ). Consequently the time to
approach equilibrium is some multiple of the clearance (or depuration) half-life. In
practice it can be very difficult to determine, on the basis of inspection alone, when
an equilibrium concentration has been reached. Furthermore, clearance half-lives
for compounds with high KQW values (octanol to water partition coefficients) are
often longer than 30 days and can approach a year. The Subcommittee
recommends that the estimation of the equilibrium concentrations be based upon
phannacokinetic modeling.
3.3.5 Toxicity Test Endpoints
In certain situations where additional information is necessary for a thorough
assessment of the biological effects component of the testing (i.e., Tier IV), it may
be appropriate to test for sublethal effects using sensitive species. Observations of
survival, growth and/or reproduction should not be abandoned. However, the
Agency and the Corps of Engineers should address the potential for genotoxic,
immunological, histopathological and other biochemical and physiological effects
which are not presently addressed by the testing guidance document. There are a
number of tests with marine organisms currently available to determine the
potential for these types of effects. These non-conventional end points should be
included as part of tier 4 in the "other sublethal effects" that should be considered
when determining the limiting permissible concentration (LPC), as stated in the
Ocean Dumping Regulations.
The responses of an organism to exposures to a given chemical are influenced
by a wide range of extrinsic and intrinsic factors. The intrinsic factors include, for
example, species, sex, life-stage, age, individual variation, genetic differences in
enzyme levels, etc. The extrinsic factors include disease history, nutritional status,
ambient physical and chemical environment, etc. The combination of these intrinsic
and extrinsic factors exert strong influences on the variability of responses to
toxicological insults. The impacts of specific factors are likely to differ when one
compares environmental exposures with laboratory tests, and exact equivalence
among responses under these two conditions is unlikely. The certain existence of
these complications demands great care of the developer of testing protocols.
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3.4 Reference Area Concept
While we agree with the reference area concept, reference areas must be
better defined and quantified (as must control areas). The collection of reference
sediment is not mentioned. Terms such as "as similar in grain size to dredged
material as practical" must be defined. Reference areas must represent test sites
as closely as practical.
The usage of the reference area concept is not clear or consistent throughout
the new "Green Book". For instance (page 1-6, Reference Sediment), it is stated
that if adequate reference sediments cannot be obtained, organisms not sensitive to
grain size should be used in testing. This statement is repeated hi the last
paragraph on page 3-1 and top of page 11-10. However, later (page 11-1, 3rd
paragraph, lines 11-12) an alternative is stated: "...or the effects of grain size have
to be determined and considered when designing benthic bioassays and evaluating
the test results." The text must clarify what is and what is not an alternative, and
must be consistent.
The decision to permit disposal of dredged materials is to a large extent
determined by the results of either toxicity or bioaccumulation tests performed with
the dredged materials and reference site sediment samples. The selection of
appropriate reference sites and the number of samples taken are critical factors in
the final decision relative to the acceptability for ocean disposal of dredged
materials. It is recommended that the reference site and sample selection guidance
provided in pages 1-6 and 3-2 be expanded. Additional guidance is needed for
determining when the "reference-point approach" should be used as compared to the
"reference area approach". This guidance should discuss the needs for an
appropriate statistical design that accounts for the variance that exists in the
reference samples and the bioassay comparisons with the dredged materials. The
statistical design should provide guidance for setting both the alpha and beta Type
I and II error levels, the number of samples needed, and the conditions under
which samples may or may not be combined for testing or analysis. Additionally,
the Subcommittee recommends that the Ocean Disposal M«"ii«l prohibit the use of
reference sediments from the proposed disposal area except where this area has not
previously been used for disposal of contaminated material.
3.5 Interpretative Guidance
Interpretative guidance is lacking in the document; each region is allowed to
proceed independently. This lack of guidance is not satisfactory as it is likely that
different regions will make different decisions and there will be no consistency.
Present provision of guidance (page 1-2, paragraph 6, lines 3-5) does not include
comprehensive information on uses, limitations, and interpretation. In some cases
(e.g., Tier IV), guidance on "...sound interpretation of the results..." is deferred to
local agencies. The Subcommittee recommends that interpretative guidance, in the
form of a framework for action, be provided now. This guidance should also
provide the user with a list of critical changes that may be appropriate relative to
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recent developments and reviews. Such action is necessary to allow for consistency
in use and decision-making, and to assist regions which do not have the technical
expertise or resources for such open-ended decision-making. Information provided
in the letter of transmittal to the draft Manual only addresses this concern in part
and is physically separated from the manual.
3.6 Tier IV Requirements
Presently, this tier is very poorly defined as regards both implementation and
rationale/usage. Clearly "chronic" tests must include a substantial portion (if not
all) of the life-cycle of a test organism. Endpoints must be related to population
dynamics: survival, growth and reproduction are key parameters to measure at the
individual organism level. Measures of growth must distinguish between somatic
and gametic growth. This tier should determine and differentiate between
statistical and ecological significance. Specifically, are the results of sensitive tests
in tier III which indicate the potential for a concern likely to be realized in the
environment? As such, there is a requirement for directed testing, not simply more
testing. The Subcommittee recommends that the manual describe some of the types
of analyses and bioassays which may be included in Tier IV and discuss the
rationale for such testing.
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4.0 SUMMARY OF RECOMMENDATIONS
a. The Subcommittee recommends that EPA revise its tiered approach to allow
revaluation at higher tiers of failures from lower tiers, to clarify the linkages
between tiers, and to emphasize reducing uncertainty as the level of tier testing
increases.
b. The Subcommittee recommends that QA/QC be a separate, detailed Section,
and that protocols be appropriate and clearly specified.
c. The Subcommittee recommends that the manual describe some of the types
of analyses and bioassays which may be included hi Tier IV and discuss the
rationale for such testing.
d. The Subcommittee recommends that a Glossary of Terms be generated and
that the terms, as defined, be used in a consistent manner throughout the
document.
e. The Subcommittee recommends elimination of redundancies and repetition
such that important information is clear, and not obscured.
f. The Subcommittee recpmmends that Table 11-1 be amended so that at least
one species with an asterisk must be tested and adult bivalves should be removed
from this list.
g. The Subcommittee recommends that Table 12-1 be amended such that
recommended species be those in intimate contact with the sediments or which
ingest sediments.
h. The Subcommittee questions whether the effort and emphasis on the
Neanthes arenaceodentata "chronic" test is warranted. We do not question a
general emphasis on polychaetes and amphipods for test development, as long as
the tests are appropriately sensitive and useful.
i. The Subcommittee recommends that the inclusion of a sensitive infaunal
amphipod or preferably an appropriately sensitive test incorporating measures of
chronic sublethal effects, as stated in the Ocean Dumping Regulations, be required
in Tier III. The tests should also be regionally appropriate.
j. The Subcommittee recommends that the issue of application factors be
revisited and that EPA produce a peer-reviewed report that provides direction on
this issue appropriate for the 1990s. Further we recommend that the manual
clearly indicate that the 0.01 application factor is only potentially applicable to
LC50s with persistent chemicals.
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k. It is recommended that appropriate consensus guidelines be drafted for
interpretation of bioaccumulation tests and that these guidelines be incorporated
into the regulatory framework. It is further recommended that the Agency conduct
studies that relate body burdens to "no observed effect levels" (NOEC) as part of
chronic toxicity protocols.
1. The Subcommittee recommends that the estimation of the equilibrium
concentrations for measuring bioaccumulation rates be based upon pharmacokinetic
modeling.
m. The Subcommittee recommends that the Ocean Disposal Manual prohibit the
use of reference sediments from the proposed disposal area, unless the area can be
shown to be free of contamination. It is recommended that the reference site and
sample selection guidance provided in pages 1-6 and 3-2 be expanded. Additional
guidance is needed for determining when the "reference-point approach" should be
used as compared to the "reference area approach".
n. The Subcommittee recommends that interpretative guidance, in the form of a
framework for action, be provided now. This guidance should also provide the user
with a list of critical changes that may be appropriate relative to recent
developments and reviews.
o. Since it is not clear how SQC will be utilized in the disposal of dredged
materials, we recommend that the applicability of sediment quality criteria to the
new "Green Book" be defined.
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