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## T ASK 

## O RDER 

## 68 UNDER 

## C ONTRACT 

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# P EER 

# R EVIEW OF THE 

# D RAFT 

# A QUATIC 

# L IFE 

# A MBIENT 

# E STUARINE 

# /M ARINE 

# W ATER 

# Q UALITY 

# C RITERIA FOR 

# C OPPER



# PEER REVIEW SUMMARY REPORT

January 4, 2016

Submitted to: 

### U.S. Environmental Protection Agency Office of Water, Office of Science and Technology Health and Ecological Criteria Division 1200 Pennsylvania Avenue, NW Washington, DC 20460 Attn: Luis Cruz Cruz.Luis@epa.gov

Submitted by: 

### Eastern Research Group, Inc. 110 Hartwell Avenue Lexington, MA 02421

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## CONTENTS

1.0 INTRODUCTION

................................ ................................ ................................ .............................. 1
1.1 Background

................................ ................................ ................................ ................................ ...... 1
1.2 Peer Revie wers

................................ ................................ ................................ ................................ 1

2.0 SUMMARY OF REVIEWER COMMENTS ORGANIZED B Y CHARGE QUESTION

................................ ..... 2
2.1 Please comment on the overall clarity of the document and construction as it relates to the derivation of each criterion.

................................ ................................ .............................. 2
2.2 Please comment on the technical approach used to derive the draft copper criteria; is it logical, does the science support the conclusion, and is it consistent with the protection of estuarine/marine aquatic life from acute, chronic, and bioaccumulative ffects?

................................ ................................ ................................ ................................ ........... 7
2.3 (a) Please comment on the data used to deriv e the revised criteria, including data adequacy/ comprehensiveness, and the appropriateness of the data selected and/or excluded from the derivation of the draft criteria.

................................ ................................ .... 14 Are there other relevant data that you are aware of that should be included? If so, please provide the criteria.

................................ ................................ ................................ ........ 15
2.4 Are the derived criteria appropriately protective of listed species and commercially and recreationally important species?

................................ ................................ ....................... 17
2.5 Other Comments Provided

................................ ................................ ................................ ......... 19

3.0 NEW INFORMATION PROV IDED BY REVIEWERS

................................ ................................ ............. 21

APPENDIX A CHARGE T O REVIEWERS

................................ ................................ ................................ ... A

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APPENDIX B INDIVIDU AL REVIEWER COMMENTS

................................ ................................ ................. B

- 1
R eviewer 1

. ................................ ................................ ................................ ................................ ....................... B

- 3
Reviewer 2

................................ ................................ ................................ ................................ ........................ B

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Reviewer 3

................................ ................................ ................................ ................................ ...................... B

- 13
Reviewer 4

................................ ................................ ................................ ................................ ...................... B

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Reviewer 5

................................ ................................ ................................ ................................ ...................... B

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1 **1.0 INTRODUCTION** 
This report documents the results of an independent peer review of the Draft Aquatic Life Ambient Estuarine/Marine Water Quality Criteria for Copper
, developed by the U.S. Environmental Protection Agency (EPA). Eastern Research Group, Inc. (ERG, a contract or to EPA) organized this review and developed this report. Section s 2 .1 to 2.4 of this report present, for each charge question, the individual reviewer comments and a summary of those comments ; Section 2.5 presents additional minor comments provided by t wo reviewer s

. New information (e.g., references) provided by reviewers is presented in Section 3. Appendices A and B provide, respectively, the charge to reviewers and the complete set of comments submitted by each reviewer.

**1.1 Background** 
EPA’s Office of Water is charged with protecting ecological integrity and human health from adverse anthropogenic, water

- mediated effects, under Section 304(a)(l) of the Clean Water Act. T o reflect the latest scientific knowledge
, t he Agency has been worki ng to update water quality criteria to protect aquatic life and aquatic

- dependent wildlife from c opper in estuarine/marine enviro nments

. EPA’s Aquatic Life Ambient Estuarine/Marine Water Quality Criteria for Copper presents draft acute and chronic criteri a expressed as concentrations of copper in estuarine/marine waters ( dissolved). The 2015 copper criteria update utilizes the recently developed marine BLM to provide updated acute and chronic water quality criteria for copper in estuarine/marine waters. The BLM is based on the premise that toxicity is related to the amount of metal bound to a biochemical site (the biotic ligand) and that binding is related to total dissolved metal and complexing ligands concentrations in the water . This differs from previ ous metals criteria which are based on empirical relationships between toxicity and water hardness

.

**1.2 Peer Reviewers** 

ERG searched for , identified, and selected five reviewers who met technical selection criteria provided by EPA and who had no conflict of in terest in performing th is review:

• Gretchen K. Bielmyer

- Fraser , Ph.D.; Associate Professor, Department of Biology, Valdosta State University

.
• David Buchwalter, Ph.D.; Associate Professor, Department of Biological Sciences, North Carolina State University

.
• Claude Fortin
, Ph.D.; Researcher, INRS

- Eau, Terre et Environnement

.
• Stephen Klaine , Ph.D.; Professor and Director, Institute of Environmental Toxicology , Clemson University

.
• Gregory Möller, Ph.D.; Professor of Environmental Chemistry and Toxicology, University of Idaho

. ERG provided reviewers with instructions, the review document (including appendices), the charge to reviewers (Appendix A of this report ) prepared by EPA, and su pplemental materials as described in the charge. R eviewers worked individually to develop written comments in response to the charge questions. After receiving reviewer comments, ERG summarized reviewers’ responses to the charge questions, noting areas of agreement and disagreement, where relevant ( see Section 2).

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2 **2.0 SUMMA**  **R Y OF REVIEWER COMMEN**  **TS ORGANIZED BY CHARGE**  **QUESTION**
This section presents summaries of reviewer comments organized by charge question. Each summary is followed by a table presenting the individual reviewer comments by charge question. Individual c omments are copied directly from written comments as submitted by each reviewer and presented in Appendix B

.

**2.1 Please comment on the overall clarity of the document and construction as it relates to the**  **derivation of each criterion.**

All reviewers found the document to be clear, and Reviewer 5 wrote that the draft document is comprehensive, accurate, persuasive , well written, and well organized

. Reviewer 1 , however, added that the Biotic Ligand Model (BLM) description section is “a bit” redundant and that the description of the final Acute to Chronic Ratio (ACR) derivation is “a bit” convoluted.
Reviewer 2 commented that the document will be useful for those charged with regulating copper in marine and estuarine waters. The r eviewer also noted that the Problem Formulation section is nicely laid out and describes the exposure scenarios well ; the case study is a nice illustration and educational tool ; Figure 5 is particularly useful; and the comparison between freshwater and marine scenarios is useful. Reviewer 4 noted that the criteria derivation is clear.

Reviewer 2 commented that a major drawback is that the BLM is an equilibrium model that does not allow for consideration of pulsed or episodic exposure with organ recovery . T he reviewer clarified that this comment was not a criticism of the document, but rather a consider ation for future research . Reviewer 3 said that it is difficult to appreciate the rigor of the approach without access to some of the cited references, and su ggested that an appendix be added. Reviewer 3 also said that the use of the term “bioavailable” is not always correct (because of the dynamic nature of metal binding, one cannot say that a particular metal species is not bioavailable), and suggested removing Section 2.5 because it is superfluous.

Reviewer 3 commented that Figures 4 through 7 are missing information that would allow the reader to understand them . This reviewer also noted that Figure 11 is not very useful with only two values and that its y- axis label should read copper instead of cadmium. Reviewer 4 had some questions about Figures 4 and 5 and noted that the discussion about these figures is confusing.

Reviewer 5 commented that the cited references represent major works in the related fi elds and, overall, are supportive of the draft document. The reviewer made several suggest ions :

• Review the final version of Chadwick et al. (2008) and update the reference accordingly

.
• In Section 2.1, b roaden the discussion to include copper sulfate use in dairy cattle footbaths , an emerging source of copper release to the environment (see the referenced Agricultural Extension publication 1 and Jokela et al.
, 2010 2 ).

• Include the reviews by Turner (2010) 3 , Thomas and Brooks (2010) 4 , and Kiaune and Singhaseman on (2011) 5 in the development of the environmental fate and transport of marine copper.

1 http://articles.extension.org/pages/22177/copper

- sulfate

- foot

- baths

- on

- dairies

- and

- crop

- toxicities
2 Jokela, WE, et al. 2010. Manure Nutrient Content on Vermont Dairy Farms: Long

- Term Trends and Relationships. Communications in Soil Science and Plant Analysis. Volume: 41 Issue: 5 Pages: 623

- 637.
3 Turner, A. 2010. Marine pollution from antifouling paint particles. Marine Pollution Bulletin. Volu me: 60 Issue: 2 Pages: 159

- 171.

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3 • Include a short comment about marine sediment copper geochemistry (e.g., Skrabal et al., 2000 6 ) in Section 2.2.

• Add Erickson (2013) 7 (a sign ificant review reference describing BLM strengths and cautionary weaknesses ) to the discussions in Section s 2.4 and 3.8.3.

Reviewer Comments EPA Response to Comments

Reviewer 1 The document is reasonably clear, albeit a bit redundant in that some of the same language is recycled several times in describing the Biotic Ligand Model (BLM).
The language regarding the derivation of the final Acute to Chronic Ratio (ACR) is a bit convoluted in the use of freshwater values.

Reviewer 2 I believe this is a very good work product and should be quite useful for those entities charged with regulating copper in marine and estuarine waters.
Problem formulation. Well done, nicely laid out and exposure scenarios described well.
Case Study. Nice illustration and should serve as educational to ol.
The comparison between freshwater and marine scenarios is also useful and should benefit the reader.
Figure 5 was particularly useful and leads the reader to figure 6.
Major drawback: It is an equilibrium model and does not allow for consideration of pulsed or episodic exposure with organism recovery. This is not necessarily a criticism of the document. Rather, it should be a consideration for future research.
How does the varying salinity in estuaries pose special challenges?

Given the obvious mechani sm of phytotoxicity for copper, it is

4 Thomas, KV and Brooks, S. 2010. The environmental fate and effects of antifouling paint biocides. Biofouling. Volume: 26 Issue: 1 Pages: 73

- 88.
5 Kiaune, L and Singhasemanon, N. 2011. Pesticidal Copper (I) Oxide: Environme ntal Fate and Aquatic Toxicity. Edited by: Whitacre, DM. Reviews of Environmental Contamination And Toxicology, VOL 213. Book Series: Reviews of Environmental Contamination and Toxicology. Volume: 213 Pages: 1

- 26.
6 Skrabal, SA et al. 2000. Pore water dist ributions of dissolved copper and copper

- complexing ligands in estuarine and coastal marine sediments. Geochimica et Cosmochimica Acta. Volume: 64 Issue: 11 Pages: 1843

- 1857.
7 Erickson. 2013 . The biotic ligand model approach for addressing effects of ex posure water chemistry on aquatic toxicity of metals: Genesis and challenges. Environmental Toxicology and Chemistry. Volume: 32 Issue: 6 Pages: 1212

- 1214.

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4 Reviewer Comments EPA Response to Comments surprising that little data exists for estuarine plants. However, it is likely that the same mechanisms that make estuarine plants tolerant to salinity likely make them less sensitive to metals such as copper.

Review er 3 a) The text is clearly written. There are some repetitions but they are probably useful to remind the reader about limits and scope of the work. It is however difficult for the reader to appreciate the rigor of the approach without reading some of the cited references such as Chadwick et al (2008) which may not be easily accessible. Perhaps an appendix could be added.
b) The use of the term “bioavailable” is, in my opinion, not always correct. Because of the dynamic nature of metal binding, one cannot say that a particular metal species is not bioavailable. This was clearly laid out in the original Morel book [1] as well as in Campbell [2] . Here is part of page 55 of the latter reference:

I have noted many st atements with such a bioavailability misconcept being conveyed: p. 1, l. 15; p. 14 (4 times); p. 47 penultimate line.
c) Figures 4, 5, 6 and 7 are lacking information for the reader to understand them. The meaning of the inserted legends is unknown. The legen d of figure 4 says “Values collapse into a single dose response when compared with measured copper accumulation” but it is not clear what this refers to. In figure 5 dotted lines are not described.
d) Section 2.5 (pp. 22

- 24) seems superfluous. Consider removi ng. e) P. 40, middle: “Application of the BLM may reduce, if not

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5 Reviewer Comments EPA Response to Comments eliminate, the need for site

- specific modifications to account for site

- specific chemistry influences on metal toxicity .” I would argue that the use of the BLM is another way to account for site specific differences. Consider rephrasing.
f) P. 11 . Last paragraph is incomplete and incoherent but I was instructed to ignore this paragraph.
g) P. 46, Figure 11: I am not convinced this figure is useful with only two values. Note also that the y

- axis label should read copper and not cadmium.

Reviewer 4 Overall the document is well written and clear as to how the criteria are derived. I do have a few minor comments, however, on areas that could be clarified.
Pgs. 17

- 18: The discussion about Figs 4 and 5 is a little confusing the way it’s presented.
Fig. 4: Define “(N)” and “(S)”.
Fig. 5: Where is the “convergence”? Please clarify the “single model representation”.

Reviewer 5 Overall the draft document content is comprehensive, accurate, and persuasive. It is well written and well organized. The cited references represent major works in the related fields and these are overall supportive of the Draft Update of Aquatic Life Ambient/Marine Water Quality Criteria for Copper (herein referred to as MWQC

- Cu ). The Chadwick et al. (2008) citation requires review and update (see detail below). The overall report is well

- written in a clear and communicative style. The report heading and subheadings are helpful to reader and present an organized development of the supp orting work for the draft acute and chronic criterion. The Table of Contents has font mismatches. The List of Figures, List of Tables, List of Appendices and Acronyms list are complete. In my reading of the report text, the balance of number of figures and number of table to sup port the development and explanation of the criterion development was satisfyingly complete. The document is well edited for correct grammar and spelling, clear sentence structure, and informative paragraph development. Paragraph tra nsitions are present and logical, and maintain the flow of thought throughout the report.
The Introduction provides overall sufficient background for

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6 Reviewer Comments EPA Response to Comments copper and previews major points in aquatic ecosystem concerns and concomitant regulatory science develop ment. Section 2.1, Overview of Copper Sources and Occur, page 5 paragraph 1 could be broadened to also include copper sulfate use in dairy cattle foot baths, an emerging source of problematic copper release to the environment because of animal hygiene and manure management practices associated with large animal agriculture operations. For example in the Agricultural Extension publication:
http ://articles.extension.org/pages/22177/copper

- sulfate

- foot

baths

- on

- dairies

- and

- crop

- toxicities

and in
Jokela, WE, et al. (2010) Manure Nutrient Content on Vermont Dairy Farms: Long

- Term Trends and Relationships COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS Volume: 41 Issue: 5 Pages: 623

- 637 DOI: 10.1080/00103620903531193
Directly germane and important in the development of the EFT of marine copper, yet absent in the citations to this report, is a significant review by Turner (2010):

Turner, A (2010) Marine pollution from antifouling paint particles MARINE POLLUTION BULLETIN Volume: 60 Issue: 2 Pages: 159

- 171 DOI: 10.1016/j.marpolbul.2009.12.004
Thomas, KV and Brooks, S (2010) The environmental fate and effects of antifouling paint biocides BIO FOULING Volume: 26 Issue: 1 Pages: 73

- 88 DOI: 10.1080/08927010903216564
The same could be said of the review by Kiaune and Singhasemanon (2011):
Kiaune, L and Singhasemanon, N (2011) Pesticidal Copper (I) Oxide: Environmental Fate and Aquatic Toxicity. Edi ted by: Whitacre, DM REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY, VOL 213. Book Series: REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY Volume: 213 Pages: 1

- 26 DOI: 10.1007/978

- 1

- 4419

- 9860

- 6_1

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7 Reviewer Comments EPA Response to Comments

Copper flux from sediments is an important EFT dynamic in marine ecosystems and a source of exposure for benthic organisms and may be a significant driver of Cu speciation and concentration in the overlaying waters. Section 2.2 of the Introduction would be strengthened by a short comment about marine s ediment Cu geochemistry such as could be developed by references such as:
Skrabal, SA et al. (2000) Pore water distributions of dissolved copper and copper

- complexing ligands in estuarine and coastal marine sediments GEOCHIMICA ET COSMOCHIMICA ACTA Volume: 64 Issue: 11 Pages: 1843

- 1857 DOI: 10.1016/S0016

- 7037(99)00387

- 7 Published: JUN 2000
Section 2.4, Overview of Historic and BLM Criteria Development Methods, would be improved with the citation and short distillation of Erickson (2013), a significan t review reference describing BLM strengths and cautionary weaknesses:
The biotic ligand model approach for addressing effects of exposure water chemistry on aquatic toxicity of metals: Genesis and challenges ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Volume: 32 Issue: 6 Pages: 1212

- 1214 DOI: 10.1002/etc.2222
Erickson (2013) would also provide significant support for the discussion of MWQC

- Cu Section 3.8.3, BLM Uncertainties and Performance.

**2.2 Please comment on the technical approach used to derive the draft**  **copper criteria; is it logical, does the science support the conclusion, and is it consistent with the protection of**  **estuarine/marine aquatic life from acute, chronic, and bioaccumulative effects?**

Reviewers 2, 3, 4 , and 5 commented that the technical approach is sound. Reviewer 2 added that it is consistent with previous BLM efforts
, as well as established methodology for developing water quality criteria. The reviewer noted that the results are sound and scientifically defensible even though short on chronic data. Reviewer 3 said that the use of the BLM is an improvement over the use of empirical hardness relationships. The reviewer added that there should be a different set of biotic ligand constants with copper for each organism and that ionic streng th is missing from the calculation of copper speciation. Reviewer 4 noted that higher temperatures may increase copper bioaccumulation and toxicity to aquatic organisms; therefore, the criteria may not be adequately protective in tropical environments. Rev iewer 5 concluded that
, with minor adjustments, the technical approach is logical, scientifically supported, and consistent with

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8 the protection of estuarine/marine aquatic life from acute, chronic and bioaccumulative effects

. The reviewer suggested that EP A briefly address the observations of d e Polo and Scrimshaw (2012) 8 and Deruytter et al. (2015) 9 in the report and consider includ ing the toxicodynamic work of de Polo et al. (2014) 10 in Section 2.3. Reviewer 5 also noted that Chadwick et al. (2008) is now final (see http://www.dtic.mil/dtic/tr/fulltext/u2/a499564.pdf ).

Reviewer 1 was concerned that the draft document ignored a lot of credible science and, therefore, that the proposed water quality criteria were based on only a portion of current scientific understanding. In particular , the reviewer described both the toxicity overview and the document’s treatment of bioaccumulative effects as substantially inadequate

. Regarding bioaccumulation, EPA only acknowledges the potential for copper toxicity via dissolved exposures , which is incomplete because dietary bioaccumulative effects are well documented in the literature and the literature also shows that copper toxicity can result from dietary exposures

. The r eviewer recommended that EPA use (1) the dissolved concentrations the diet was exposed to as an exposure descriptor
, and (2) the BLM to better understand exposures via water and ingestion. This reviewer also was ver y uncomfortable with the language, on page 33, about the stability of marine waters and its application to estuarine waters, which are less stable.

Reviewer Comments EPA Response to Comments

Reviewer 1 I have a lot of respect for the scientific merit associated with the BLM. If toxicity of Cu was exclusively based on surficial binding and associated osmoregulatory effects, the approach used in this WQC would be fine. Unfortunately, a lot of credible scie nce is ignored, and a WQC is being proposed that only uses a portion of our scientific understanding. The criteria is based on a narrow literature evaluation of copper toxicity. It ignores literature that shows dietary Cu bioaccumulation and effects (e.g. Bielmeyer paper that was not considered because the exposure route was via diet). It only acknowledges a segment of what is known about Cu toxicity in general (all biota) and in aquatic organisms specifically. The oxidative toxicity of Cu is ignored comple tely despite dozens of papers that describe it in aquatic organisms.

I've attached a new book chapter that may be helpful. (Bielmeyer and Grosell, Chapter 5: Emerging issue in marine metal toxicity.)

8 de Polo, A and Scrimshaw, MD. 2012. Challenges for the development of a biotic ligand model predic ting copper toxicity in estuaries and seas. Environmental Toxicology and Chemistry. Volume: 31 Issue: 2 Pages: 230

- 238.
9 Deruytter, D, et al. 2015. Salinity and dissolved organic carbon both affect copper toxicity in mussel larvae: Copper speciation or co mpetition cannot explain everything. Environmental Toxicology and Chemistry. Volume: 34 Issue: 6 Pages: 1330

- 1336.
10 de Polo, A, et al. 2014. A New Role for Carbonic Anhydrase 2 in the Response of Fish to Copper and Osmotic Stress: Implications for Multi

- S tressor Studies. Plos One. Volume: 9 Issue: 10 Article Number: e107707.

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9 Reviewer Comments EPA Response to Comments The treatment of bioaccumulative effects is terribly inadequate, particularly in light of the lack of chronic data. It is well established that invertebrates receive considerable tissue concentrations of metals from their diets. It is also well established that Cu that is not detoxified can be a potent pro

- o xidant. This is acknowledged as only occurring in mammals in this document despite abundant literature describing this phenomenon in aquatic organisms. It seems that EPA is only acknowledging the potential for toxicity via dissolved exposures. This is inco mplete. It seems as though EPA discounts metal bioaccumulation as potentially problematic because a single tissue effects threshold does not exist. If toxicity can result from dietary exposures (shown in the literature), there should be no problem in using the dissolved concentrations that the diet was exposed to as a descriptor of exposure.
P. 1: “The biotic ligand is the gill surface and the site of toxicity on the organism”. This statement is only partially true. Gill binding is associated with toxicity , most likely via interactions with ion transport systems and carbonic anhydrase. However this is not the only way copper causes toxicity (see comment above). Bioaccumulated Cu (from all exposure routes) has the potential to be toxic as well.
P. 12: Figur e 2 is not particularly informative.
P. 12: The overview of toxicity is woefully inadequate. This is an exceptionally well

- studied metal. There is no reason for this section to not provide a comprehensive overview of what is known about Cu toxicity.

P. 1 3: With all of the work that has examined the bioavailability of Cu from sediments, the only thing mentioned is AVS? (AVS is not universally recognized and is highly controversial among knowledgeable scientists.
P. 16 Figure 3: Shouldn’t the anions and th eir importance in complexation reactions be portrayed here?
P. 16: Again, the overly simplistic and incomplete view of toxicity is expressed here.
P. 17: It is interesting that whole body accumulation values are used here. It is interesting that the interpretation is that whole body accumulation is related

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10 Reviewer Comments EPA Response to Comments to surficial binding, with surficial binding being the cause of toxicity where it could very we ll be that toxicity results from whole body accumulation. Along those lines, it opens up the idea that bioaccumulated Cu is potentially important, and the simple BLM

- only view of the world is not complete.
P. 24: The conceptual model includes ingestion bu t none of the acceptable data include ingestion as an exposure route. This is a huge source of uncertainty. Importantly, the BLM could be used to better understand both direct exposure via water, and ingestion pathways because it is well known that water c hemistry affects Cu uptake in phytoplankton (which is typically accumulative).

P. 31: section 2.8.2 check gramma r of first sentence.
P. 33: These criteria apply to marine and estuarine waters......I’m very uncomfortable with the language about the stability of marine waters and its application to estuarine waters as well (which are less stable).

P. 34: I’m not sure about the use of the term “threshold” to describe an LC50.

P. 38: What is a 96 hour static multi

- generational test?

P. 39: What if rot ifers were fed a diet that was equilibrated to the same copper concentrations? Would the toxicity values be expected to change?

P. 41 Table 8: I assume the 2°C is a typo?
P. 46 Figure 11: check Y axis label. This is a copper criterion not a cadmium criterion.

It is in teresting that copper is used as an aquatic herbicide, yet several times in the text it is noted that toxicity to plants is comparable to toxicity in animals. Shouldn’t this raise concerns?

Reviewer 2 The technical approach is sound and consistent with both previous BLM efforts as well as the established methodology for deve loping water quality criteria. Table 3 lays out the data, summary statistics and metrics and should be easily understood by the reader. While a little short on chronic data, the resul ts are sound and scientifically defensible.

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11 Reviewer Comments EPA Response to Comments

Reviewer 3 a) I think the use of the BLM is an improvement over the use of empirical hardness relationships. The BLM approach is based on sound premises and previous successful applications.
b) P. 17: “An advantage of the BLM is that most of the parameters are invariant for different organisms, despite the complexity of the modeling framework. All of the thermodynamic constants used to simulate inorganic and organic chemical equilibrium reactions are determined by ch aracteristics of the metal and the available ligands. As such, the constants do not change for simulations involving different organisms. ” That is true for all reactions between metals and ligands in solution but there should be a different set of biotic l igand constants with copper for each organism. The way this paragraph is written may mislead the reader.
c) A missing piece of information is related to the calculation of copper speciation. In saltwater, the ionic strength is 0.7 M. At such a high ionic stre ngth, adjustment of binding constants is not straightforward. The commonly used empirical relations of Davies or Debye

- Hückel cannot be used. How does the BLM account for ionic strength?

Reviewer 4 The technical approach used to derive the draft copper

c riteria is logical and scientifically sound. The premise of the BLM and the input parameters are adequately explained. A limitation is that the criteria may not be adequately protective in tropical environments. The BLM uses a temperature of 22 0 C and higher temperatures may increase copper bioaccumulation and toxicity to aquatic organisms.

Reviewer 5 The MWQC

- Cu relies heavily on the Environmental Security Technology Certification Program U.S. Department of Defense (ESTCP

- DoD) study cited as:
Chadwick, D.B., I. Rivera

- Duarte, P.F. Wang, G. Rosen, R. Santore, P. Paquin and A. Ryan. 2008. Demonstration of an integrated compliance model for predicting copper fate and effects in DoD Harbors, Environmental Security Technology Certification Program ( ESTCP). Project ER

- 0523, Draft Final

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12 Reviewer Comments EPA Response to Comments Technical Report, June 16, 2008

. This citation should be updated to the “ Final Report November 1, 2008 ” as found at http://www.dtic.mil/dtic/tr/fullte xt/u2/a499564.pdf if the authors view the modifications from the draft to the final report for Project ER

- 0523 to be not significant or substantial with regards to the application of this report and its seawater BLM parameters to the development of the MWQ C

- Cu. I could not locate the Draft Final Technical Report, June 16, 2008.
The Chadwick et al. (2008) project report does not appear to have made it into the peer

- reviewed literature using my Web of Science searches for “Chadwick, D.B/author”, “copper biot ic ligand model/topic” or “marine biotic ligand model/topic” or “seawater biotic ligand model/topic.” While this is unfortunate in the development of the MWQC

- Cu, exemplified by descriptors in the report referring to “emerging” seawater BLM, I explored thi s reference in sufficient detail to support it as a primary and well

- executed scientific resource in the development of the MWQC

- Cu. The role and expertise of some of the Project ER

- 0523 report authors as the primary scientists responsible for the well

- est ablished freshwater BLM science

– which is a significant advancement in water quality risk management

– lends significant support for application of the Project ER

- 0523 report as a key resource in support of the MWQC

- Cu. In particular, the laboratory valid ation approaches cited as SERDP Projects ER

- 1156 and ER

- 1157 in Chadwick et al. (2008) appear as significant bench validation of seawater Cu behavior in application the BLM. As reported in Chadwick et al. (2008), the seawater BLM tested well against a rigo rous set of model validation performance metrics. This effort coupled with the knowledge of an almost constant competing cation load and inorganic ligand load of seawater relative to freshwater, as illustrated in Figure 3, secures the high stability and ad aptability of the BLM in a seawater application and thus in the development of the MWQC

- Cu. Thus I conclude that the overall technical model approach of the seawater BLM

– if there is concordance between the Draft Final Technical Report, June 16, 2008 as c ited with the Final Report November 1, 2008

– is scientifically sound and supported.

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13 Reviewer Comments EPA Response to Comments There are two recent papers by Deruytter, et al. that are not cited in the present draft report. The work:
Deruytter, D, et al. (2014) The Combined Effect of Dissolved Or ganic Carbon and Salinity on the Bioaccumulation of Copper in Marine Mussel Larvae ENVIRONMENTAL SCIENCE & TECHNOLOGY Volume: 48 Issue: 1 Pages: 698

- 705 DOI: 10.1021/es4024699

and
Deruytter, D, et al. (2015) Salinity and dissolved organic carbon both affect copper toxicity in mussel larvae: Copper speciation or competition cannot explain everything ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Volume: 34 Issue: 6 Pages: 1330

- 1336 DOI: 10.1002/etc.2924 Deruytter, D, et al. (2015) appears to expand on the

conce rns of work published by de Polo and Scrimshaw (2012) that suggests incorporation of an osmotic gradient into the seawater BLM since the intestine can also be a biotic ligand.
de Polo, A and Scrimshaw, MD (2012) Challenges for the development of a biotic ligand model predicting copper toxicity in estuaries and seas ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Volume: 31 Issue: 2 Pages: 230

- 238 DOI: 10.1002/etc.1705
The primary driver of the MWQC

- Cu is the work of Chadwick et al (2008), but because it never appea red in the primary peer

- reviewed literature, it is uncited in de Polo and Scrimshaw (2012) or Deruytter, D, et al. (2015). Figure 8 of the MWQC

- Cu describing the Conceptual Model for Copper Effects on Aquatic Organisms shows gills and integument and thus appears to address some of the concerns of de Polo and Scrimshaw (2012). Coupled with the practical description of the well

supported salinity sensitivity of some Cu sensitive juvenile test species (e.g. Mytilus ) discussed on page 21 there appears to be solid data to directly and briefly address the observations of de Polo and Scrimshaw (2012) and Deruytter, D, et al. (2015) within the MWQC

Cu draft report. In addition, the follow

- up toxicodynamic

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14 Reviewer Comments EPA Response to Comments work of de Polo, A, et al. (2014) may be very usefu l the MWQC

- Cu Section 2.3, Overview of Copper Toxicity:
de Polo, A, et al. (2014) A New Role for Carbonic Anhydrase 2 in the Response of Fish to Copper and Osmotic Stress: Implications for Multi

- Stressor Studies PLOS ONE Volume: 9 Issue: 10 Article Number: e107707 DOI: 10.1371/journal.pone.0107707
With the minor adjustments outlined above, the technical approach used to derive the draft copper criteria is logical, scientifically supported, and is consistent with the protection of estuarine/marine aquatic li fe from acute, chronic, and bioaccumulative effects.

**2.3 (a)**  **Please comment on the data used to derive the revised criteria, including data adequacy/ comprehensiveness, and the appropriateness of the data selected and/or**  **excluded from the derivation of the draft criteria.** 

Reviewer 2 thought that the data used to generate the new criteria we re sound, the approach wa s transparent, and the results we re in line with what would be expected from examining current data

. Reviewer 5 commented that the peer

- reviewed and published data included in the report were complete and comprehensive.
Reviewer 1 reiterated that excluding dietary studies was unfortunate and troubling
, and repeated the recommendation that EPA use the exposure concentration the food is exposed to as an exposure descriptor.

Reviewer 3 could not find a rationale for the use of 1.3 mg/L as the amount of dissolved organic carbon. This reviewer r ecommended that EPA includ e a sensitivity analysis to better understand the influence this parameter has on the aquatic life criteria. R eviewer 1 also suggested that EPA provide information on uncertainty of the data when that information is available, perform error propagation calculations when possible, and reduce the number of significant figures to two.

Reviewer 3 commented that the rationale for accepting/rejecting data wa s not provided and suggested including an appendix to summarize the decision criteria

. Reviewer 4 also commented that including a list of criteria for d ata inclusion would be helpful.

Reviewer 4 thought that the acute data used to derive the criterion maximum concentration (CMC) we re adequate and comprehensive ; however, the chronic data we re severely lacking. Even so, th is reviewer said that the approach used to derive the criterion continuous concentration (CCC) was logical and that the CCC should be protective of most aquatic organisms.

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15 **(b) Are there other relevant data that you are aware of that should be included? If so,**  **please provide the criteria.**

Reviewers 1 and 4 both disagreed with excluding Bielmyer ’s work from the report. Reviewer 1 commented that , to alleviate the uncertainties about toxicity, industry should support the generation of chronic tests that include the use of food that has been eq uilibrated with the identical aqueous solutions used as the exposure water to the test animals. Reviewer 5 suggested including the findings from Oliveira et al. (2014). 11 Reviewers 2 and 3 did not suggest additional data.

Reviewer Comments EPA Response to Comments

Reviewer 1 The exclusion of dietary studies is unfortunate and does not reflect the current scientific understanding of metal toxicology. The exclusion of the Bielmyer papers is particularly without scientific justification. I understand the need to relate WQC to dissolved concentrations here, but the exposure concentration that the food is exposed to can be used as a descriptor of exposure.
EPA’s failure to consider all exposure routes is very troubling. This would be analogous to setting a tolerance for a chemical residue on a food but not considering drinking water as important in a human health hazard assessment. Are there other relevant data that you are aware of that should be included? If so, please provide the criteria.
Industry shoul d support the generation of chronic tests that include the use of food that has been equilibrated with the identical aqueous test solutions used as the exposure water to the test animals. Only then will uncertainties about toxicity be alleviated.

Reviewer 2 The additional data used to generate the new criteria are sound and the approach transparent. Results are in line with what would be expected by simply examining the current data set.
Are there other relevant data that you are aware of that shou ld be included? If so, please provide the criteria.

No.

11 Oliveira, BL. 2014. Acute copper toxicity in juvenile fat snook Centropomus parallelus ( Teleostei: Centropomidae ) in sea water. Neotropical Ichthyology. Volume: 12 Issue: 4 Pages: 84 5

- 852.

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Reviewer 3 a) Here the rationale for accepting /rejecting data is not provided. It might be useful to include an appendix to summarize how these decisions are made without having to dig up the report o n this method.
b) One of the key parameters of the proposed copper BLM that influence the resulting values is the amount of dissolved organic carbon. I could not find a rationale for the use of the value of 1.3 mg/L. There is only a reference to a footnote in appendix A. A sensitivity analysis would be useful for the reader to appreciate the influence of this parameter on the aquatic life criteria.
c) It would be useful for the reader to get an idea of the uncertainty on the values given throughout the report. Th is could be done through several changes: i) provide uncertainty on data when available (for every mean values, a standard error can be computed); ii) perform error propagation calculations when possible, if not warn reader about the potential error; and i ii) reduce the number of significant figures to two (I have seen many values with five significant figures; these mislead the reader to think that these values are very accurate).

Reviewer 4 The acute data used to derive the CMC are both adequate and comprehensive; however the chronic data are severely lacking, with data provided from only two animal species and no plant species. I do agree that criteria protective of animals should also theoretically be protective of plants, given that plants are gene rally more tolerant. That is a logical assumption. Even with the limited number of species in the chronic toxicity data set, the approach used to derive the CCC was logical and the CCC should be protective of most aquatic organisms.
Tables are provided in appendices listing the unused data and the reasons for not using them. However, adding a list of the criteria necessary for data/studies to be included would be helpful (i.e., minimum number of animals, etc.). I do not think that I saw that in this documen t.

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Are there other relevant data that you are aware of that should be included? If so, please provide the criteria.
(See the answer to question #4).

Reviewer 5 My review of MWQC

- Cu Section 3 and Section 4 and the related report citations suggests a complete and comprehensive inclusion of the available peer

- reviewed and published data validated for application to this purpose. For this review I did not access the individual pa pers to validate that the data was correctly used and transcribed in the context of the original citation.

Are there other relevant data that you are aware of that should be included? If so, please provide the criteria. My search of the marine/seawater Cu toxicity literature found only one marine aquatic toxicity reference uncited in the MWQC

- Cu draft document, Oliveira, et al. (2014). My brief assessment of the findings of this work suggest it would not change the criterion developed in the MWQC

- Cu, howev er the authors may wish to confirm this and add this reference for completeness.
Oliveira, BL (2014) Acute copper toxicity in juvenile fat snook Centropomus parallelus (Teleostei: Centropomidae) in sea water NEOTROPICAL ICHTHYOLOGY Volume: 12 Issue: 4 Pag es: 845

- 852 DOI: 10.1590/1982

- 0224

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**2.4 Are the derived criteria appropriately protective of listed species and commercially and**  **recreationally important species?**

Reviewer 2 commented that the derived criteria are appropriate, protective, and scientifically defensible. Reviewer 5 said that the acute and chronic criteria are a major step forward in marine/estuarine management of copper , and noted that the derived criteria are appropriately protective of listed species and commercially and recrea tionally important species. Reviewer 5 commented that the authors followed accepted pathways of aquatic ecosystem risk analysis and risk management using best available knowledge and practices
, and were honest about the limitations inherent with all modeli ng approaches.
Reviewer 1 responded that EPA’s failure to consider all exposure routes leads to uncertainty about whether the criteria are protective. Reviewer 4 pointed out that because symbiotic organisms were not included, they may not be protected by the copper CCC, particularly in tropical environments.

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18 Reviewer 3 did not respond because this question was outside the reviewer’s area of expertise, but noted that the few commercially and recreationally important species we re well identified in the report.

Reviewer Comments EPA Response to Comments

Reviewer 1 I think ignoring all exposure routes leads to uncertainty here.

Reviewer 2 In my opinion the derived criteria are appropriate, protective and scientifically defensible

.

Reviewer 3 This question falls out of my area of expertise. However, the few commercially and recreationally important species are well identified in the report.

Reviewer 4 I think that the Bielmyer et al., 2010 paper (listed in the unused data table) should have been included because it presented chronic data about a sensitive tropical coral species that had been listed as threatened under the ESA. It was not included because the coral are symbiotic and contained algae housed in their coral exoskeleton. If the algae were separated from the coral, then the coral would be stressed, and toxicity data from those organisms would be skewed. Because symbiotic organisms are not included, they may not be protected by the copper CCC, particularly in t ropical environments. This is another limitation of the chronic data set.

Reviewer 5 In my review of the draft report the MWQC

- Cu, the derived criteria are appropriately protective of listed species and commercially and recreationally important species, by direct inclusion or extrapolation from published work. The authors have followed accepted pathways of aquatic ecosystem risk analysis and risk management, using best available knowledge and practices accepted in the major disciplinary areas overlapped i n this complex challenge. In my view, the BLM has been satisfactorily adapted to seawater/marine environments within the generally accepted limitations of all modeling approaches. The MWQC

- Cu draft report is honest about these limitations and the major MWQ C

- Cu citation of Chadwick et al. (2008) explicitly and exhaustively explores the practical and economic limitations of quantitative risk assessment/management

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19 Reviewer Comments EPA Response to Comments and the advantages of using well vetted models in a complex scenario of dynamic variables, multip le stressors, and multiple receptors. In this regard the acute and chronic criteria developed are a major step forward in marine/estuarine management of copper.

**2.5 Other**  **Comments Provided** 

Reviewer Comments EPA Response to Comments

Reviewer 3 Other comments:

• Foreword, 1 st paragraph: “copper” rather than “cadmium”.

• Throughout the text there is an inconsistent use of: spacing before and after equal (=) signs; spacing between parentheses; e.g. “)(“ or “)_(“; “fresh water” and “freshwater”; “salt water” and “saltwater”.

• Acronyms missing on page xii: MDR; GMCV

.

• P. 4: Not clear to me why “registration” and “reregistration” are both used

.

• P. 11: “...which form of Cu +1 or Cu +2 is found...” OR “...which form s of Cu +1 or Cu +2 are found...”

• P. 11: “...the free cupric (Cu 2 + ) ion may be present”: the use of the word “may” suggests that this species may be absent which is physically impossible. All species are always present but the s e concentrations may be very low.

• P. 12, Figure 2: “forms” or “chemical species” instead of “s trategy”?

• P. 21: Check font size for “μ”.

• P. 22, last line: Delete extra period.

• P. 33: HCO 3

.

• P. 40, penultimate line: while alkalinity

. References cited : [1] Morel FMM ed. 1983. Principles of Aquatic Chemistry.

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20 Reviewer Comments EPA Response to Comments John Wiley & Sons, New York, NY, USA.
[2] Campbell PGC. 1995. Interactions between trace metals and aquatic organisms: A critique of the free

ion activity model. In Tessier A, Turner DR, eds, Metal Speciation and Bioavailability in Aquatic Systems

. John Wiley & Sons, New York, N Y, USA, pp 45

- 102.

Reviewer 4 Minor Comments:
Pg. 16 and Fig. 6: Delete blue outline around figures.
Pg. 22, last line: Delete the double period.
Pg. 26, Table 2: Change “cadmium” to “copper”
Pg. 32, 1 st sentence: Delete “to”
Pg. 40, second to last line: Change “whilealinity” to “while salinity”
Pg. 41, Table 8: Change the temperature to “22” instead of “2”
Table 9, 1 st line: Delete the space after “FAV” before “:”
Fig. 11: Change “cadmium” to “copper”
Appendix F: Delete “Unused” as it is redundant.

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21 **3.0 NEW INFORMATION PROV**  **IDED BY REVIEWERS**

This section presents all new information that reviewers provided in addition to or within their specific responses (presented in Section 2, above) to t he charge questions

.

Reviewer New Information Provided EPA Response to Comment s

Reviewer 1 Bielmeyer and Grosell, Chapter 5: Emerging issue in marine metal toxicity.

Reviewer 5 Question 1
Agricultural Extension publication: http://articles.extension.org/pages/22177/copper

sulfate

- foot

- baths

- on

- dairies

- and

- crop

- toxicities Jokela, WE, et al. (2010) Manure Nutrient C ontent on Vermont Dairy Farms: Long

- Term Trends and Relationships COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS Volume: 41 Issue: 5 Pages: 623

- 637 DOI: 10.1080/00103620903531193

T urner, A (2010) Marine pollution from antifouling paint particles MARINE POLLUTION BULLETIN Volume: 60 Issue: 2 Pages: 159

- 171 DOI: 10.1016/j.marpolbul.2009.12.004

Th omas, KV and Brooks, S (2010) The environmental fate and effects of antifouling paint biocides BIOFOULING Volume: 26 Issue: 1 Pages: 73

- 88 DOI: 10.1080/089270109 03216564

K iaune, L and Singhasemanon, N (2011) Pesticidal Copper (I) Oxide: Environmental Fate and Aquatic Toxicity. Edited by: Whitacre, DM REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY, VOL 213. Book Series: REVIEWS OF ENVIRONMENTAL CONTAMINATIO N AND TOXICOLOGY Volume: 213 Pages: 1

- 26 DOI: 10.1007/978 -1- 4419

- 9860

- 6_1

Skrabal, SA et al. (2000) Pore water distributions of

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22 Reviewer New Information Provided EPA Response to Comment s dissolved copper and copper

- complexing ligands in estuarine and coastal marine sediments GEOCHIMICA ET COSMOCHIMICA ACTA Volume : 64 Issue: 11 Pages: 1843

- 1857 DOI: 10.1016/S0016

- 7037(99)00387

- 7 Published: JUN 2000 Erickson (2013), a significant review reference describing BLM strengths and cautionary weaknesses:
The biotic ligand model approach for addressing effects of exposure water chemistry on aquatic toxicity of metals: Genesis and challenges ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Volume: 32 Issue: 6 Pages: 1212

- 1214 DOI: 10.1002/etc.2222

Question 2
Deruytter, D, et al. (2014) The Combined Effect of Dissolved Organic Carbon and Salinity on the Bioaccumulation of Copper in Marine Mussel Larvae ENVIRONMENTAL SCIENCE & TECHNOLOGY Volume: 48 Issue: 1 Pages: 698

- 705 DOI: 10.1021/es4024699

Deruytter, D, et al. (2015) Salinity and dissolved organic carbon both affect copper toxicit y in mussel larvae: Copper speciation or competition cannot explain everything ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Volume: 34 Issue: 6 Pages: 1330

- 1336 DOI: 10.1002/etc.2924

de Polo, A and Scrimshaw, MD (2012) Challenges for the development of a biotic ligand model predicting copper toxicity in estuaries and seas ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Volume: 31 Issue: 2 Pages: 230

- 238 DOI: 10.1002/etc.1705

de Polo, A, et al. (2014) A New Role for Carbonic Anhydrase 2 in the Response of Fish to Copper and Osmotic Stress: Implications for Multi

- Stressor Studies PLOS ONE Volume: 9 Issue: 10 Article Number: e107707 DOI: 10.1371/journal.pone.0107707

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Question 3

Ol iveira, BL (2014) Acute copper toxicity in juvenile fat snook Centropomus parallelus (Teleostei: Centropomidae) in sea water NEOTROPICAL ICHTHYOLOGY Volume: 12 Issue: 4 Pages: 845

- 852 DOI: 10.1590/1982

- 0224

- 20140040

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- 029 Task Order 68 November 2015



## External Letter Peer Review of EPA’s Draft Aquatic Life Ambient Estuarine/Marine Water Quality Criteria for Copper

BACKGROUND The U.S. Environmental Protection Agency (EPA) Office of Water is charged with protecting ecological integrity and human health from adverse anthropogenic, water

- mediated effects, under the purview of the Clean Water Act (CWA). In support of this mission, EPA is working to update water quality criteria to protect aquatic life and aquatic

- dependent wildlife from the presence of copp er in estuarine/marine environments. EPA’s document presents draft acute and chronic criteria expressed as concentrations of copper in estuarine/marine waters (dissolved). Criteria for copper were last updated in 2007. The 2007 release only updated freshwa ter criteria and differed from EPA’s previous metals criteria primarily based on how metal availability to organisms is addressed with use of the biotic ligand model (BLM). The BLM is based on the premise that toxicity is related to the amount of metal bou nd to a biochemical site (the biotic ligand) and that binding is related to total dissolved metal and complexing ligands concentrations in the water, and differs from previous metals criteria which are based on empirical relationships between toxicity and water hardness. The 2015 copper criteria update utilizes the recently

- developed marine BLM to provide updated acute and chronic water quality criteria for copper in estuarine/marine waters.

CHARGE QUESTIONS
The draft document provided is the focus of this review. Model files have been provided to reviewers as supplemental information only and it is not required to run the model or review these files (at your discretion).

1. Please comment on the overall clarity of the document and construction as it relates t o th e d erivation of each criterion.

2. P lease comment on the technical approach used to derive the draft copper criteria; is it logical, does the science support the conclusion, and is it consistent with the protection of estuarine/marin e aq uatic life from acute, chronic, and bioaccumulative effects?

3. P lease comment on the data used to derive the revised criteria, including dat a

a dequacy/comprehensiveness, and the appropriateness of the data selected and/or excluded from the derivation of the draft criteria.

A re there other relevant data that you are aware of that should be included? If so, please provide the criteria.

4. A re the derived criteria appropriately protective of listed species and commercially and recreationally important species?

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### External Letter Peer Review of EPA’s Draft Aquatic Life Ambient Estuarine/Marine Water Quality Criteria for Copper

1. Please comment on the overall clarity of the document and construction as it relates to the derivatio n
o f each criterion.

The document is re asonably clear, albeit a bit redundant in that some of the same language is recycled several times in describing the Biotic Ligand Model (BLM).
The language regarding the derivation of the final Acute to Chronic Ratio (ACR) is a bit convoluted in the use of freshwater values.

2. Please comment on the technical approach used to derive the draft copper criteria; is it logical, does the science support the conclusion, and is it consistent with the protection of estuarine/marine aquatic life from acute, chronic, and bioaccumulative effects?
I have a lot of respect for the scientific merit associated with the BLM. If toxicity of Cu was exclusively based on surficial binding and associated osmoregulatory effects, the approach used in this WQC would be fine. Unfo rtunately, a lot of credible science is ignored, and a WQC is being proposed that only uses a portion of our scientific understanding. The criteria is based on a narrow literature evaluation of copper toxicity. It ignores literature that shows dietary Cu b ioaccumulation and effects (e.g. Bielmeyer paper that was not considered because the exposure route was via diet). It only acknowledges a segment of what is known about Cu toxicity in general (all biota) and in aquatic organisms specifically. The oxidative toxicity of Cu is ignored completely despite dozens of papers that describe it in aquatic organisms.
I've attached a new book chapter that may be helpful. (Bielmeyer and Grosell, Chapter 5: Emerging issue in marine metal toxicity.)

The treatment of bioac cumulative effects is terribly inadequate, particularly in light of the lack of chronic data. It is well established that invertebrates receive considerable tissue concentrations of metals from their diets. It is also well established that Cu that is not d etoxifie d can be a potent pro

- oxidant. This is acknowledged as only occurring in mammals in this document despite abundant literature describing this phenomenon in aquatic organisms. It seems that EPA is only acknowledging the potential for tox icity via di ssolved exposures. This is incomplete. It seems as though EPA discounts metal bioaccumulation as potentially problematic because a single tissue effects threshold does not exist. If toxicity can result from dietary exposures (shown in the literature), ther e should be no problem in using the dissolved concentrations that the diet was exposed to as a descriptor of exposure.

P. 1 : “The biotic ligand is the gill surface and the site of toxicity on the organism”. This sta tement is only partially true. Gill binding is associated with toxicity, most likely via interactions with ion transport systems and carbonic anhydrase. However this is not the only way copper causes toxicity (see comment above). Bioaccumulated Cu (from all exposure routes) has the potential to be toxic as well.

P. 1 2: Figure 2 is not particularly informative.

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B-6 P. 1 2: The overview of to x icity is woefully inadequate. This is an exceptionally well

- studied metal. There is no reason for this section to not provide a comprehensive overview of what is known about Cu toxicity.

P. 1 3: With all of the work that has examined the bioavailability of Cu from sediments, the only thing mentioned is AVS? (AVS is not universally recognized and is highly controversial among knowledgeable sci entists.

P. 1 6 Figure 3: Shouldn’t the anions and their importance in complexation reactions be portrayed here?

P. 1 6: Again, the overly simplistic and incomplete view of toxicity is expressed here.

P. 1 7: It is interesting that whole body accumulation values are used here. I t is interesting that the interpretation is that whole body accumulation is related to surficial binding, with surficial binding being the cause of toxicity where it could very well be that toxicity results from whole body accumulation. Along those lines, it opens up the idea that bioaccumulated Cu is potentially important, and the simple BLM

- only view o f th e world is not complete.

P. 2 4: The conceptual model includes ingestion but none of the acceptable data include i n gestion as an exposure route. This is a huge source of uncertainty. Importantly, the BLM could be used to better understand both direct exposure via water, and ingestion pathways because it is well known that wate r chemistry affects Cu uptake in phytoplankton (which is typically accumulative)

.

P. 3 1: section 2.8.2 check gramma r o f first sentence

. P. 33: These criteria apply to marine and estuarine waters......I’m very uncomfortable with the language about the stability of marine waters and its application to estuarine waters as well (which are less stable)

.

P. 3 4. I’m not sure about the use of the term “threshold” to describe an LC50

.

P. 3 8: What is a 96 hour static multi

- generational test?

P. 3 9: What if rotifers were fed a diet that was equilibrated to t he same copper concentrations? Would the toxicity values be expected to change?

P. 4 1 Table 8: I assume the 2°C is a typo?

P. 4 6: Figure 11: check Y axis labe l. This is a copper criterion not a cadmium criterion.
It is interesting that copper is used as an aquatic herbicide, yet several times in the text it is noted that toxicity to plants is compa rable to toxicity in animals. Shouldn’t this raise concerns?

3. Please comment on the data used to derive the revised criteria, including data adequacy/ comprehensiveness, and the appropriateness of the data selected and/or excluded from the derivation of the draft criteria.
The exclusion of dietary studies is unfortunate and does not reflect the current scientific unde rstanding of metal toxicology. The exclusion of the Bielmyer papers is particularly wi thout scientific justification. I

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B-7 understand the need to relate WQC to dissolved concentrations here, but the exposure concentration that the food is exposed to can be used as a descriptor of exposure.
EPA’s failure to consider all expo sure routes is v ery troubling. This would be analogous to setting a tolerance for a chemical residue on a food but not considering drinking water as important in a human health hazard
assessment.

Are there other relevant data that you are aware of that should be included? If so, please provide the criteria.
Industry should support the generation of chronic tests that include the use of food that has been equilibrated with the identical aqueous test solutions used as the exposu re water to the test animals. Only then will uncertainties about toxicity be alleviated.

4. Are the derived criteria appropriately protective of listed species and commercially and recreationally important species?
I think ignoring all exposure routes leads to uncertainty here

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1. Please comment on the overall clarity of the document and construction as it relates to the derivatio n
o f each criterion.
I believe this is a very good work product and should be quite useful for those entities charged with regulating copper in marine and estuarine waters.
Problem formulation. Well done, nicely laid out and exposur e scenarios described well.
Case Study. Nice illustration and should serve as educational tool.
The comparison between freshwater and marine scenarios is also useful and should benefit the reader.
Figure 5 was particularly useful and leads the reader to f igure 6.
Major drawback: It is an equilibrium model and does not allow for consideration of pulsed or episodic exposure with organism recovery. This is not necessarily a criticism of the document. Rather, it should be a consideration for future research.
How does the varying salinity in estuaries pose special challenges?
Given the obvious mechanism of phytotoxicity for copper, it is surprising that little data exists for estuarine plants. However, it is likely that the same mechanisms that make estuarine plants tolerant to salinity likely make them less sensitive to metals such as copper.

2. Please comment on the technical approach used to derive the draft copper criteria; is it logical, does the science support the conclusion, and is it consistent with the protection of estuarine/marine aquatic life from acute, chronic, and bioaccumulative effects?
The technical approach is sound and consistent with both previous BLM efforts as well as the established methodology for developing water quality criteria. Table 3 lays out the data, summary statistics and metrics and should be easily understood by the reader. While a little short on chronic data, the results are sound and scientifically defensible.

3. Please comment on the data used to derive the revised criteria, incl uding data adequacy/ comprehensiveness, and the appropriateness of the data selected and/or excluded from the derivation of the draft criteria.
The additional data used to generate the new criteria are sound and the approach transparent. Results are in li ne with what would be expected by simply examining the current data set.

Are there other relevant data that you are aware of that should be included? If so, please provide the criteria.

No.

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B- 12 4. Are the derived criteria appropriately protective of listed species and commercially and recreationally important species?
In my opinion the derived criteria are appropriate, protective and scientifically defensible.

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1. Please comment on the overall clarity of the document and construction as it relates to the derivatio n
o f each criterion.
a) The text is clearly written. There are some repetitions but they are probably useful to remind th e

re ader about limits and scope of the work. It is however difficult for the reader to appreciate the rigor of the approach without reading some of the cited references such as Chadwick et al

. (2008) which may not be easily accessible. Perhaps an appendix could be added.
b) The use of the term “bioavailable” is, in my opinion, not always correct. Because of the dynamic nature of metal binding, one cannot say that a particular metal species is not bioavailable. This was clearly laid out in the original Morel book [1] as well as in Campbell [2] . Here is part of page 55 of th e l atter reference:

I have noted many statements with such a bio availability misconcept being conveyed: p. 1, l. 15; p. 14 (4 times); p. 47 penultimate line.
c) Figures 4, 5, 6 and 7 are lacking information for the reader to understand them. The meaning of the inserted legends is unknown. The legend of figure 4 says “Values collapse into a single dose response when compared with measured copper accumulation” but it is not clear what this refers to. In figure 5 dotted lines are not described.
d) Section 2.5 (pp. 22

- 24) seems superfluous. Consider removing.
e) P. 40, middle: “Application of the BLM may reduce, if not eliminate, the need for site

- specific modifications to account for site

- specific chemistry influences on metal toxicity.” I would argue that the use of the BLM is another way to account for site specific differences. Consider rephrasing.

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B- 16 f) P. 11. Last paragraph is incomplete and incoherent but I was instructed to ignore this paragraph.
g) P. 46, Figure 11: I am not convinced this figure is useful with only two values. Note also that the y

axis label should read copper a nd not cadmium.

2. Please comment on the technical approach used to derive the draft copper criteria; is it logical, does the science support the conclusion, and is it consistent with the protection of estuarine/marine aquatic life from acute, chronic, and bioaccumulative effects?
a) I think the use of the BLM is an improvement over the use of empirical hardness relationships. The BLM approach is based on sound premises and previous successful applications.
b) P. 17: “An advantage of the BLM is that most of the par ameters are invariant for different organisms, despite the complexity of the modeling framework. All of the thermodynamic constants used to simulate inorganic and organic chemical equilibrium reactions are determined by characteristics of the metal and the available ligands. As such, the constants do not change for simulations involving different organisms.” That is true for all reactions between metals and ligands in solution but there should be a different set of biotic ligand constants with copper for ea ch organism. The way this paragraph is written may mislead the reader.
c) A missing piece of information is related to the calculation of copper speciation. In saltwater, the ionic strength is 0.7 M. At such a high ionic strength, adjustment of binding consta nts is not straightforward. The commonly used empirical relations of Davies or Debye

- Hückel cannot be used. How does the BLM account for ionic strength?

3. Please comment on the data used to derive the revised criteria, including data adequacy/ comprehensiven ess, and the appropriateness of the data selected and/or excluded from the derivation of the draft criteria. Are there other relevant data that you are aware of that should be included? If so, please provide the criteria.
a) Here the rationale for accepting / rejecting data is not provided. It might be useful to include an appendix to summarize how these decisions are made without having to dig up the report on this method.
b) One of the key parameters of the proposed copper BLM that influence the resulting value s is th e

am ount of dissolved organic carbon. I could not find a rationale for the use of the value of 1.3 mg/L. There is only a reference to a footnote in appendix A. A sensitivity analysis would be useful for the reader to appreciate the influence of this parameter on the aquatic life criteria.
c) It would be useful for the reader to get an idea of the uncertainty on the values given throughout the report. This could be done through several changes: i) provide uncertainty on data when available (for every mean values, a standard error can be computed); ii) perform error propagation calculations when possible, if not warn reader about the potential error; and iii) reduce the number of significant figures to two (I have seen many values with five significant fig ures; these mislead th e

re ader to think that these values are very accurate).

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B- 17 4. Are the derived criteria appropriately protective of listed species and commercially and recreationally important species?
This question falls out of my area of expertise. How ever, the few commercially and recreationally important species are well identified in the report.

Other comments:

• Foreword, 1 st paragraph: “copper” rather than “cadmium”.

• Throughout the text there is an inconsistent use of: spacing before and after equal (=) signs; spacin g b etween parentheses; e.g. “)(“ or “)_(“; “fresh water” and “freshwater”; “salt water” and “saltwater”.

• Acronyms missing on page xii: MDR; GMCV

.

• P. 4: Not clear to me why “registration” and “reregistration” are both used

.

• P. 11: “...which form of Cu +1 or Cu +2 is found...” OR “...which form s of Cu +1 or Cu +2 are found...”

• P. 11: “...the free cupric (Cu 2+ ) ion may be present”: the use of the word “may” suggests that this species may be absent which is physically impossible. All species are always pres ent but there concentrations may be very low.

• P. 12, Figure 2: “forms” or “chemical species” instead of “strategy”?

• P. 21: Check font size for “μ”.

• P. 22, last line: Delete extra period.

• P. 33: HCO 3.

• P . 40, penultimate line: while alkalinity

.
References cited : [1] Morel FMM ed. 1983. Principles of Aquatic Chemistry. John Wiley & Sons, New York, NY, USA.

[2] Campbell PGC. 1995. Interactions between trace metals and aquatic organisms: A critique of the free

ion activity model. In Tessier A, Turner DR, eds, Metal Speciation and Bioavailability in Aquatic Systems

. Jo hn Wiley & Sons, New York, NY, USA, pp 45

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## COMMENTS SUBMITTED B Y

Reviewer 4This Page intentially left blank

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### External Letter Peer Review of EPA’s Draft Aquatic Life Ambient Estuarine/Marine Water Quality Criteria for Copper

1. Please comment on the overall clarity of the document and construction as it relates to the derivatio n
o f each criterion.

Overall the document is well written and clear as to how the criteria are derived. I do have a few minor comments, however, on areas that could be clarified

. Pgs. 17

- 18: The discussion about Figs 4 and 5 is a little confusing the way it’s presented.

Fig. 4: Define “(N)” and “(S)”.

Fig. 5: Where is the “convergence”? Please clarify the “single model representation”.

2. Please comment on the technical approach used to derive the draft copper criteria; is it logical, does the science support the conclusion, and is it consistent with the protection of estuarine/marine aquatic life from acute, chronic, and bioaccumulative effects?
The technical approach used to deriv e the draft copper criteria is logical and scientifically sound. The premise of the BLM and the input parameters are adequately explained. A limitation is that the criteria may not be adequately protective in tropical environments. The BLM uses a temperatu re of 22 0 C and higher temperatures may increase copper bioaccumulation and toxicity to aquatic organisms.

3. Please comment on the data used to derive the revised criteria, including data adequacy/comprehensiveness, and the appropriateness of the data selected and/or excluded from the derivation of the draft criteria.
The acute data used to derive the CMC are both adequate and comprehensive; however the chronic data are severely lacking, with data provided from only two animal species and no plant species. I do agree that criteria protective of animals should also theoretically be protective of plants, given that plants are generally more tolerant. That is a logical assumption. Even with the limited number of species in the chronic toxicity data set, the app roach used to derive the CCC was logical and the CCC should be protective of most aquatic organisms.
Tables are provided in appendices listing the unused data and the reasons for not using them. However, adding a list of the criteria necessary for data/stu dies to be included would be helpful (i.e. minimum number of animals, etc.). I do not think that I saw that in this document.
Are there other relevant data that you are aware of that should be included? If so, please provide the criteria.
(See the answer to question #4 .)

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B- 22 4. Are the derived criteria appropriately protective of listed species and commercially and recreationally important species?
I think that the Bielmyer et al.
, 2010 paper (listed in the unused data table) should have been included because it presented chronic data about a sensitive tropical coral species that had been listed as threatened under the ESA. It was not included because the coral are symbiotic and contained algae housed in their coral exoskeleton. If the algae were separated from the coral, then the coral would be stressed, and toxicity data from those organisms would be skewed. Because symbiotic organisms are not included, they may not be protected by the copper CCC, particularly in tropical environments. This is another limitation of the chronic data set.

Mi nor Comments:
Pg. 16 and Fig. 6: Delete blue outline around figures.
Pg. 22, last line: Delete the double period.
Pg. 26, Table 2: Change “cadmium” to “copper”

Pg. 32, 1 st sentence: Delete “to”
Pg. 40, second to last line: Chan ge “whilealinity” to “while salinity”
Pg. 41, Table 8: Change the temperature to “22” instead of “2”

Table 9, 1 st line: Delete the space after “FAV” before “:”

Fig. 11: Change “cadmium” to “copper”
Appendix F: Delete “Unused” as it is redundant.

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## COMMENTS SUBMITTED B Y

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### External Letter Peer Review of EPA’s Draft Aquatic Life Ambient Estuarine/Marine Water Quality Criteria for Copper

1. Please comment on the overall clarity of the document and construction as it relates to the derivation of each criterion.
Overall the draft document content is comprehensive, accurate, and persuasive. It is well written and well organized. The cited references represent major works in the related fields and these are overall supportive of the Draft Update of Aquatic Life Ambient/Marine Water Quality Criteria for Copper (herein referred to as MWQC

- Cu ). The Chadwick et al. (2008) citation requires review and update (see detail below). The overall report is well

- writ ten in a clear and communicative style. The report heading and subheadings are helpful to reader and present an organized development of the supporting work for the draft acute and chronic criterion. The Table of Contents has font mismatches. The List of F igures, List of Tables, List of Appendices and Acronyms list are complete. In my reading of the report text, the balance of number of figures and number of table to support the development and explanation of the criterion development was satisfyingly compl ete. The document is well edited for correct grammar and spelling, clear sentence structure, and informative paragraph development. Paragraph transitions are present and logical, and maintain the flow of thought throughout the report.
The Introduction pro vides overall sufficient background for copper and previews major points in aquatic ecosystem concerns and concomitant regulatory science development. Section 2.1, Overview of Copper Sources and Occur, page 5 paragraph 1 could be broadened to also include copper sulfate use in dairy cattle foot baths, an emerging source of problematic copper release to the environment because of animal hygiene and manure management practices associated with large animal agriculture operations. For example in the Agricultura l Extension publication:
http://articles.extension.org/pages/22177/copper

- sulfate

- foot

- baths

- on

- dairies

- and

- crop

- toxicities

and in
Jokela, WE, et al. (2010) Manure Nutrient Content on Vermont Dairy Farms: Long

- Term Trends and Relationships COMMUNICATIONS IN SOIL SCIENCE AND PLANT ANALYSIS Volume: 41 Issue: 5 Pages: 623

- 637 DOI: 10.1080/00103620903531193

Directly germane and important in the d evelopment of the EFT of marine copper, yet absent in the citations to this report, is a significant review by Turner (2010): Turner, A (2010) Marine pollution from antifouling paint particles MARINE POLLUTION BULLETIN Volume: 60 Issue: 2 Pages: 159

- 171 D OI: 10.1016/j.marpolbul.2009.12.004

T homas, KV and Brooks, S (2010) The environmental fate and effects of antifouling paint biocides BIOFOULING Volume: 26 Issue: 1 Pages: 73

- 88 DOI: 10.1080/08927010903216564

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B- 26 The same could be said of the review by Kiaune and Singhasemanon (2011):
Kiaune, L and Singhasemanon, N (2011) Pesticidal Copper (I) Oxide: Environmental Fate and Aquatic Toxicity. Edited by: Whitacre, DM REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY, VOL 213. Book Series: REVIEWS OF ENVIRONMEN TAL CONTAMINATION AND TOXICOLOGY Volume: 213 Pages: 1

- 26 DOI: 10.1007/978 -1- 4419

- 9860

- 6_1
Copper flux from sediments is an important EFT dynamic in marine ecosystems and a source of exposure for benthic organisms and may be a significant driver of Cu speciation and concentration in the overlaying waters. Section 2.2 of the Introduction would be strengthened by a short comment about marine sediment Cu geochemistry such as could be developed by references such as:
Skrabal, SA et al. (2000) Pore water distrib utions of dissolved copper and copper

- complexing ligands in estuarine and coastal marine sediments GEOCHIMICA ET COSMOCHIMICA ACTA Volume: 64 Issue: 11 Pages: 1843

- 1857 DOI: 10.1016/S0016

- 7037(99)00387 -7 Published: JUN 2000
Section 2.4, Overview of Historic and BLM Criteria Development Methods, would be improved with the citation and short distillation of Erickson (2013), a significant review reference describing BLM strengths and cautionary weaknesses:
The biotic ligand mode l approach for addressing effects of exposure water chemistry on aquatic toxicity of metals: Genesis and challenges ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Volume: 32 Issue: 6 Pages: 1212

- 1214 DOI: 10.1002/etc.2222
Erickson (2013) would also provide significant support for the discussion of MWQC

- Cu Section 3.8.3, BLM Uncertainties and Performance.

2. Please comment on the technical approach used to derive the draft copper criteria; is it logical, does the science support the conclusion, and is it consistent with the protection of estuarine/marine aquatic life from acute, chronic, and bioaccumulative effects?

The MWQC

- Cu relies heavily on the Environmental Security Technology Certification Program U.S. Department of Defense (ESTCP

- DoD ) study cited as:
Chadwick, D.B., I. Rivera

- Duarte, P.F. Wang, G. Rosen, R. Santore, P. Paquin and A. Ryan. 2008. Demonstration of an integrated compliance model for predicting copper fate and effects in DoD Harbors, Environmental Security Technology Certification Program (ESTCP). Project ER

- 0523, Draft Final Technical Report, June 16, 2008

. This citation should be updated to the “ Final Report November 1, 2008 ” as found at http://www.dtic. mil/dtic/tr/fulltext/u2/a499564.pdf if the authors view the modifications from the draft to the final report for Project ER

- 0523 to be not significant or substantial with regards to the application of

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B- 27 this report and its seawater BLM parameters to the deve lopment of the MWQC

- Cu. I could not locate the Draft Final Technical Report, June 16, 2008.
The Chadwick et al. (2008) project report does not appear to have made it into the peer

- reviewed literature using my Web of Science searches for “Chadwick, D.B/aut hor”, “copper biotic ligand model/topic” or “marine biotic ligand model/topic” or “seawater biotic ligand model/topic.” While this is unfortunate in the development of the MWQC

- Cu, exemplified by descriptors in the report referring to “emerging” seawater B LM, I explored this reference in sufficient detail to support it as a primary and well

- executed scientific resource in the development of the MWQC

- Cu. The role and expertise of some of the Project ER

- 0523 report authors as the primary scientists responsibl e for the well

- established freshwater BLM science – which is a significant advancement in water quality risk management – lends significant support for application of the Project ER

- 0523 report as a key resource in support of the MWQC

- Cu. In particular, th e laboratory validation approaches cited as SERDP Projects ER

- 1156 and ER

- 1157 in Chadwick et al. (2008) appear as significant bench validation of seawater Cu behavior in application the BLM. As reported in Chadwick et al. (2008), the seawater BLM tested w ell against a rigorous set of model validation performance metrics. This effort coupled with the knowledge of an almost constant competing cation load and inorganic ligand load of seawater relative to freshwater, as illustrated in Figure 3, secures the hig h stability and adaptability of the BLM in a seawater application and thus in the development of the MWQC

Cu. Thus I conclude that the overall technical model approach of the seawater BLM – if there is concordance between the Draft Final Technical Report, June 16, 2008 as cited with the Final Report November 1, 2008 – is scientifically sound and supported.
There are two recent papers by Deruytter, et al. that are not cited in the present draft report. The work:
Deruytter, D, et al. (2014) The Combined Effe ct of Dissolved Organic Carbon and Salinity on the Bioaccumulation of Copper in Marine Mussel Larvae ENVIRONMENTAL SCIENCE & TECHNOLOGY Volume: 48 Issue: 1 Pages: 698

- 705 DOI: 10.1021/es4024699

and Deruytter, D, et al. (2015) Salinity and dissolved organic carbon both affect copper toxicity in mussel larvae: Copper speciation or competition cannot explain everything ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Volume: 34 Issue: 6 Pages: 1330

- 1336 DOI: 10.1002/etc.2924
Deruytter, D, et al. (2015) appears to expan d on the concerns of work published by de Polo and Scrimshaw (2012) that suggests incorporation of an osmotic gradient into the seawater BLM since the intestine can also be a biotic ligand.
de Polo, A and Scrimshaw, MD (2012) Challenges for the development of a biotic ligand model predicting copper toxicity in estuaries and seas ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY Volume: 31 Issue: 2 Pages: 230

- 238 DOI: 10.1002/etc.1705

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B- 28 The primary driver of the MWQC

- Cu is the work of Chadwick et al (2008), but because it never appeared in the primary peer

- reviewed literature, it is uncited in de Polo and Scrimshaw (2012) or Deruytter, D, et al. (2015). Figure 8 of the MWQC

- Cu describing the Conceptual Model for Copper Effects on Aquatic Organisms shows gills and integument and thus appears to address some of the concerns of de Polo and Scrimshaw (2012). Coupled with the practical description of the well

- supported salinity sensitivity of some Cu sensitive juvenile test species (e.g. Mytilus ) discussed on page 21 there appears to be solid data to directly and briefly address th e observations of de Polo and Scrimshaw (2012) and Deruytter, D, et al. (2015) within the MWQC

- Cu draft report. In addition, the follow

- up toxicodynamic work of de Polo, A, et al. (2014) may be very useful the MWQC

- Cu Section 2.3, Overview of Copper Toxici ty:
de Polo, A, et al. (2014) A New Role for Carbonic Anhydrase 2 in the Response of Fish to Copper and Osmotic Stress: Implications for Multi

- Stressor Studies PLOS ONE Volume: 9 Issue: 10 Article Number: e107707 DOI: 10.1371/journal.pone.0107707

With the minor adjustments outlined above, the technical approach used to derive the draft copper criteria is logical, scientifically supported, and is consistent with the protection of estuarine/marine aquatic life from acute, chronic, and bioaccumulative effects.

3. Please comment on the data used to derive the revised criteria, including data adequacy/ comprehensiveness, and the appropriateness of the data selected and/or excluded from the derivation of the draft criteria.
My review of MWQC

- Cu Section 3 and Sec tion 4 and the related report citations suggests a complete and comprehensive inclusion of the available peer

- reviewed and published data validated for application to this purpose. For this review I did not access the individual papers to validate that the data was correctly used and transcribed in the context of the original citation.

Are there other relevant data that you are aware of that should be included? If so, please provide the criteria.
My search of the marine/seawater Cu toxicity literature foun d only one marine aquatic toxicity reference uncited in the MWQC

- Cu draft document, Oliveira, et al. (2014). My brief assessment of the findings of this work suggest it would not change the criterion developed in the MWQC

- Cu, however the authors may wish
t o confirm this and add this reference for completeness.
Oliveira, BL (2014) Acute copper toxicity in juvenile fat snook Centropomus parallelus (Teleostei: Centropomidae) in sea water NEOTROPICAL ICHTHYOLOGY Volume: 12 Issue: 4 Pages: 845

- 852 DOI: 10.1590/ 1982

- 0224

- 20140040

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B- 29 4. Are the derived criteria appropriately protective of listed species and commercially and recreationally important species?
In my review of the draft report the MWQC

- Cu, the derived criteria are appropriately protective of listed speci es and commercially and recreationally important species, by direct inclusion or extrapolation from published work. The authors have followed accepted pathways of aquatic ecosystem risk analysis and risk management, using best available knowledge and practices accepted in the major disciplinary areas overlapped in this complex challenge. In my view, the BLM has been satisfactorily adapted to seawater/marine environments within the generally accepted limitations of all modeling approaches. The MWQC

- Cu draft report is honest about these limitations and the major MWQC

- Cu citation of Chadwick et al. (2008) explicitly and exhaustively explores the practical and economic limitations of quantitative risk assessment/management and the advantages of using well vetted models in a complex scenario of dynamic variables, multiple stressors, and multiple receptors. In this regard the acute and chronic criteria developed are a major step forward in marine/estuarine management of copper.