ms. tessa fojut january 20, 2017 page 2 · review. these draft water quality criteria (wqc) and...

Ms. Tessa Fojut

January 20, 2017

Page 2

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January 20, 2017

Ms. Tessa Fojut

Central Valley Regional Water Quality Control Board

11020 Sun Center Drive Ste. 200

Rancho Cordova, CA 95670-6114

Via electronic mail: [email protected]

SUBJECT: Comments on the Central Valley Regional Water Quality

Control Board’s Draft Water and Sediment Quality

Criteria Report for Fipronil (October 2016)

Dear Ms. Fojut:

The Sacramento Regional County Sanitation District (Regional San)

appreciates the opportunity to comment on the Water and Sediment Quality

Criteria Report for Fipronil (10/2016) (draft Report) developed by the

University of California, Davis (UCD) (Bower and Tjeerdema, 2016).

Regional San owns and operates the Sacramento Regional Wastewater

Treatment Plant, and provides wastewater collection, conveyance and

treatment services to over 1.4 million residents and thousands of commercial

and industrial customers in the Sacramento region. We offered some general

comments on the draft Report in our November 9, 2016 letter, responding to

peer review questions, and are providing more specific comments in an

attachment to this letter that led to our main concerns listed below.

Regional San understands the Central Valley Regional Water Quality Control

Board’s interest and efforts to protect the environment from adverse effects

due to pesticides. However, we have concerns about the continual use of Clean

Water Act authority to address potential environmental impacts from

pesticides, rather than being proactive and focusing on the pesticide

registration/review process to evaluate the fate, transport, and toxicity of new

pesticides with the goal of reducing impacts to water quality.

In addition we have the following concerns with the draft report that are

detailed in the attached CH2M Tech Memo, which are intended to improve

deficiencies in the draft report.

mailto:Tessa.fojut@waterboards

Ms. Tessa Fojut

January 20, 2017

Inappropriate use of assessment factors resulting in too much conservatism, which can

unnecessarily burden public agencies, as well as industry without providing any higher level

of environmental protection.

Lack of data regarding ambient concentrations in water or sediment, for understanding the

relevance of the draft criteria.

Uncertainty is not adequately addressed.

Use of sublethal toxicity data for deriving acute Water Quality Criteria (WQC) is highly

conservative.

Relative and reliable ranking for sublethal toxicity results and non-standard test organisms

have many quality deficiencies.

Inappropriate use of sublethal toxicity data in the determination of acute WQC when the

linkage has not been clearly made between survival, growth or reproduction and chronic

toxicity.

We request you consider recirculating a revised draft of the report after responding to comments by

the peer reviewers, and others, addressing deficiencies in the draft Report.

Thank you for your considerations. Please contact me at (916) 876-6030, [email protected], if

you have any questions.

Sincerely,

Linda Dorn

Environmental Program Manager

cc: Lisa Thompson, Regional San

Christoph Dobson, Regional San

Terrie Mitchell, Regional San

Tim Mussen, Regional San

Attachment: January 20, 2017, CH2M Tech Memo, Comments on draft Water and Sediment Quality

Criteria Report for Fipronil. Phase III: Application of the Pesticide Water and Sediment Quality

Criteria Methodologies. Prepared for the Central Valley Regional Water Quality Control Board by

Bower and Tjeerdema. UC Davis. October, 2016

M E M O R A N D U M

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Comments on the draft Water and Sediment Quality Criteria Report for Fipronil. Phase III: Application of the Pesticide Water and Sediment Quality Criteria Methodologies. Prepared for the Central Valley Regional Water Quality Control Board by Bower and Tjeerdema. UC Davis. October, 2016.

PREPARED FOR: Linda Dorn/SRCSD

PREPARED BY: Cameron Irvine/CH2M

Christine Arenal/CH2M

DATE: January 20, 2017

PROJECT NUMBER: 386701

Introduction

Draft criteria for the protection of aquatic life from the insecticide Fipronil and degradates (Draft Report) have been provided by the Central Valley Regional Water Quality Control Board (CVRWQCB) for public review. These draft water quality criteria (WQC) and sediment quality criteria (SQC) are based on derivation techniques developed by the UC Davis (TenBrook et al., 2009; Fojut et al. 2014) for the CVRWQCB. As confirmed in the Draft Report, the necessary toxicity studies are insufficient to use standard USEPA (1985) methodology to develop the criteria, and the UC Davis approach allows for this. WQC and SQC for some Fipronil degradates were not calculated due to insufficient data to meet the UC Davis criteria derivation requirements. The resulting draft Report presents conservative WQC and SQC due to the use of Assessment Factors (AFs) that are used to fill data gaps. These comments were prepared based on a technical review of the Draft Report and supporting documentation on behalf of the Sacramento County Regional Sanitation District.

Documents: http://www.swrcb.ca.gov/rwqcb5/water_issues/tmdl/central_valley_projects/central_valley_pesticides/criteria_method/index.shtml

Specific comments regarding inconsistencies and calculation errors

SC-1) The draft report incorrectly identifies data as survival when it is for sublethal toxicity endpoints. Section 10.1.2 for Fipronil-sulfide erroneously states that the lowest LC50 value was 9.3 ng/L for Chironomus dilutus (Weston and Lydy 2014). Rather, the reported value is an EC50 and the correct LC50 value is >62.4 ng/L (the LC50 could not be calculated as it was greater than the highest tested concentration). Likewise, Section 10.1.3 for Fipronil-sulfone erroneously states that the lowest LC50 value was 7.9 ng/L for Chironomus dilutus (Weston and Lydy 2014). Rather, the reported value is an EC50 and the corresponding LC50 value is >106 ng/L (the LC50 could not be calculated as it would be

http://www.swrcb.ca.gov/rwqcb5/water_issues/tmdl/central_valley_projects/central_valley_pesticides/criteria_method/index.shtml

http://www.swrcb.ca.gov/rwqcb5/water_issues/tmdl/central_valley_projects/central_valley_pesticides/criteria_method/index.shtml

COMMENTS ON THE DRAFT WATER AND SEDIMENT QUALITY CRITERIA REPORT FOR FIPRONIL. PHASE III: APPLICATION OF THE PESTICIDE WATER AND SEDIMENT QUALITY CRITERIA METHODOLOGIES. PREPARED FOR THE CENTRAL VALLEY REGIONAL WATER QUALITY CONTROL BOARD BY BOWER AND TJEERDEMA, OCTOBER 2016

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greater than the highest tested concentration). Test 1 results for the midge in this study actually report the lowest EC50 of 7.5 ng/L Fipronil-sulfone and lowest LC50 as >102 ng/L.

SC-2) It is not clear why Fojut et al (2014), a method for deriving SQC, is referenced for the AF approach to calculate the WQC for Fipronil-sulfide (Section 7.1.2). There are also conflicting AFs in Table 3.13 of TenBrook et al. (2009) and Table 17 in Fojut et al. (2014) that should be reconciled so that the WQC calculation approach is clear and an explanation is needed if the more recent SQC associated AFs from 2014 are used instead of those in the 2009 WQC method.

SC-3) Figure 6 shows one interpretation of acute toxicity data for Fipronil-sulfone, but the regression is extrapolated over an order of magnitude below the lowest data point. There is great uncertainty when extrapolating beyond the ranges of data. It would be very helpful to add confidence intervals onto Figure 6 to more accurately describe the error around the 1st and 5th percentile estimates as was done in Figure 4. Adding both the upper and lower 95% confidence limits around these entire regressions would be even more helpful in describing the accuracy of these regressions.

SC-4) The chronic WQC for Fipronil-sulfide is calculated as 0.13 ng/L (Section 7.2.2) but then is incorrectly described in the final criteria statement (Section 12.3) as 0.10 ng/L. There is no discussion of the significant figures used to calculate this WQC that would change the number of significant figures and concentrations in McNamera (1990b), which is the basis for this WQC, and were reported to two significant figures.

SC-5) The text in Section 7.2.4 (Page 20) states that the only chronic aqueous toxicity value for Fipronil-desulfinyl is an MATC of 1.67 µg/L for Daphnia magna; however, Table 12 only lists one MATC for D. magna and the value is 64 µg/L. Please correct this inconsistently.

SC-6) Section 8.1.1 (page 21) incorrectly references Table 16 when Table 15 is the correct table containing Fipronil final acute sediment toxicity data.

SC-7) Section 8.1.4 (page 23) incorrectly references Table 17 when it should refer to Table 18 for the lowest sediment EC50 for Fipronil-desulfinyl.

SC-8) Section 8.1.4 (page 23) has an incorrect conversion from 1.166 µg/g OC to 1.2 ng/g OC Fipronil-desulfinyl. The correct result is 1166 or 1200 ng/g OC (if rounded to two significant figures). This error is carried forward to Section 12.3 (page 40) where the interim acute SQC is incorrectly presented.

SC-9) Likewise, Section 8.2.4 (page 25) has an incorrect conversion from 0.204 µg/g OC to 0.20 ng/g OC for the Fipronil-desulfinyl interim chronic SQG. The correct value is 204 ng/g OC. This error is carried forward to Section 12.3 (page 40) where the interim chronic SQC is incorrectly presented.

SC-10) Throughout the document there is a misuse of the singular when referring to data (plural). Datum is the singular form. For example, see page 40.

“Fipronil and degradates have been monitored in urban environments in California and a summary of this these data is are given to provide context for the use of water quality criteria for these compounds.”

SC-11) Section 10.3 (page 29) incorrectly references Table 23 when Table 22 is the correct table.

SC-12) Section 12.2 (Page 37) ambiguously states that “The lowest SMAV in the RR data set of 0.04 µg/g OC…concentration of x ng/L…” Please provide the missing value for “x” which we expect is 0.26 ng/L.


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SC-13) There is no ‘summary’ of ambient monitoring data for Fipronil and its degradates as stated in the last paragraph (page 40). Rather, there is a text discussion of detection frequencies, but no concentration data are presented. Measured ambient concentrations are essential for interpreting the relevance of these draft WQC and SQC and should be presented when available. This discussion also seems to be in the wrong place since it refers to Fipronil and degradates yet it is in a section for Fipronil-desulfinyl.

SC-14) Weston and Lydy (2013) (page 40) and TenBrook et al. (2009a) (page 26) are cited in the Draft Report but are missing from the References Section.

SC-15) The Draft Report does not define if SQC are based on a dry weight or wet weight sediment concentration basis. This would be helpful to clarify.

SC-16) Tables 3 and 8 incorrectly identify the toxicity endpoints for Fipronil in Weston and Lydy (2014). Table 3 refers to these as survival endpoints but the values presented are for the sublethal immobilization response. Whereas Table 8 refers to the results as immobilization when reporting the result for survival. These data are also recorded incorrectly in Appendix A. The effect concentration for Helicopsyche sp. in table 8 is also incorrectly reported as >842 µg/L when Weston and Lydy (2014) state the LC50 is >0.842 µg/L as presented.

SC-17) Please explain what a bold LC/EC50 value indicates in Tables 3-7, 9-12, and 15-20.

SC-18) An incorrect value of 0.0634 µg/L EC50 was used in the Fipronil species sensitivity distribution modelling (Appendix E) instead of the reported value of 0.634 µg/L.

SC-19) Some of the RL, LR, and LL data described in Appendix A2 are not shown in Table 14 (see detailed comments for Appendix).

SC-20) Toxicity test result rankings should be performed separately for multiple endpoints in a single study. The Draft Report separately evaluated rankings for different species and chemical combinations from individual sources, but various endpoints, which have different methods and control requirements, should be considered independently.

General Comments

GC-1) The overall uncertainty with each draft WQC and SQC is very high and this should be clearly indicated to environmental managers who might adopt them for regulatory use. Some of these uncertainties are discussed in Section 12; however, they are underemphasized and there is not a comprehensive uncertainty discussion or estimate of the magnitude of uncertainty to inform responsible management use of these WQC and SQC. The following points deserve additional recognition and discussion in Section 12.

Data were insufficient for calculations using EPAs (1985a) WQC protocols. Therefore, SSDs were developed with fewer data than EPA would accept, or Assessment Factors (AFs) were applied to the lowest toxicity value to compensate for the lack of data. Fojut et al (2014) illustrates in Table 17 that the use of AFs will almost always result in acute values lower than the SSD 5th percentile, often by more than one order of magnitude.

Water quality properties (e.g. dissolved organic carbon and total suspended solids) that could bind hydrophobic contaminants and protect aquatic organisms from chemical exposure are not considered in the draft WQC. These are variables in ambient surface waters (more so in stormwater) that are lacking in laboratory toxicity testing waters and increases the conservative nature of toxicity


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test data. Effect levels in lab toxicity tests will therefore be lower than those in ambient waters due to these naturally occurring constituents in surface water.

The use of sublethal toxicity data for deriving acute WQC is highly conservative (see comments below).

The most sensitive response is selected for use in the criteria calculation when multiple test results are available for a chemical-organism combination in a study. It is not clear why the most sensitive result is used from identical test repetitions rather than the geometric mean of the results, which would be a more accurate reflection of the average organism response and reduce uncertainty introduced from test variability.

Uncertainty in the 5th percentile estimate of the SSD increases as the number of data points decreases. When only three points are used in the SSD (too few data for SSD calculations with the UCD method) the 95th percentile confidence interval on the median 5th percentile of the SSD can vary by a factor of 10 to 1x10^6, depending on the calculation method (Pennington 2003). Including the 95% confidence intervals around each SSD regression would help to illustrate the precision around each regression, or lack thereof.

As a result, as discussed in Section 10 (page 27), The acute Fipronil SQC (4.2 ng/g OC) is two orders of magnitude lower than the most sensitive effect in any sediment test with this chemical (10-day EC50 of 100 ng/g OC for C. dilutus). The chronic Fipronil-sulfide WQC (0.1 ng/L) is three orders of magnitude lower than the lowest MATC (470 ng/L). The chronic Fipronil-sulfide SQC (0.4 ng/g OC) is also three orders of magnitude lower than the lowest MATC (160 ng/g OC for immobilization of C. dilutus). These vast differences between the toxicity data and draft derived criteria should raise concern that the criteria are overly conservative. All of these criteria are derived from a sub-lethal endpoint (immobilization) that has not been clearly linked with survival or growth, albeit for a sensitive species. Caution is therefore urged for resource managers considering their use in regulation.

GC-2) Toxicity results from Weston and Lydy (2014) comprise a large proportion of the toxicity data determined to be Relevant and Reliable. However, it is not clear how they received this RR ranking for sublethal toxicity results and non-standard test organisms given many quality deficiencies. Many of the invertebrates used in these tests were collected from urban streams with no evaluation of the stressors organisms were exposed to prior to collection. Because organisms secured from a wild population lack any guarantee that they will be of the age, size, quality, or condition needed for performing bioassays, procedures exist for proper evaluation and acclimation (USEPA 1985b). ASTM E1706-05 (2010) recommends avoiding tests with organisms from wild populations unless cultured through several generations to help address these concerns. Test organisms should also be identified using an appropriate taxonomic key, and verification should be documented. Furthermore, the degree of manipulation and stress that would have been required to identify these invertebrates to the species level would presumably stress them enough to render them unreliable for a bioassay without a substantial acclimation period. These wild organisms were collected, identified, and used for bioassays after only 24-hours. Laboratory toxicity data for field collected organisms (i.e., as reported in Weston and Lydy 2014) should therefore be considered with caution and not used as a primarily line-of-evidence in WQC derivation unless it meets all the described quality criteria.

Further, control survival was less than 90%, an accepted test acceptability criterion for short-term tests, for many of the species and endpoints. Weston and Lydy (2014) state that “90% is often used as a threshold for acceptability when testing with standard species,” but that the standards should be relaxed when testing a non-standard species in sub-optimal testing conditions. However, Chironomus dilutus is a commonly used, “standard” bioassay species (formerly known as Chironomus tentans) and standard methods have been developed. EPA (2002) states that control organism survival in short-term


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acute toxicity tests must be greater than 90% and ASTM E1706-05 (2010) guidance agrees that 90% control organism survival is a minimum test acceptability criteria. Furthermore, precedence suggests that 90% control survival is important even when using non-standard species/procedures. Specifically, in a review of Fipronil studies, EPA (USEPA 2006) classified a study of Hexagenia sp. (one of the species used in Weston and Lydy, 2014) as invalid due to failure to meet a 90% control survival standard.

We are also concerned over the efficacy of using subjective sublethal toxicity endpoints (i.e., ‘ability to swim’, ‘ability to thrash when prodded’, ‘ability to cling’, and ‘ability to crawl’) for deriving acute WQC. It has not been clearly demonstrated that these results are reproducible among labs, among different cohorts or populations of wild animals, or that the range of ‘normal’ behaviors have been adequately described. Interlaboratory comparisons have shown high variability when evaluating this immobilization response1. The range of control results for these behaviors are also not described in Weston and Lydy (2014). Therefore, it is not known if or how the sublethal toxicity endpoints were compared to a control response and the lack of sublethal performance controls should disqualify these results from an RR rating (note that he survival in a control treatment is not a valid basis for assessing the control performance of sublethal responses). The basis for sublethal toxicity endpoint interpretations should be made clear before these data are used in WQC derivation.

Finally, the reliability scores for this study do not seem to have followed the UC Davis WQC derivation Method (Tables 3.7 and 3.8 in TenBrook et al. 2009). Results for sublethal behavioral endpoints in Weston and Lydy (2014) should have been assessed Acceptability Rating points based on the lack of appropriate controls (6) and control response within test guidance (8). Acceptability Rating points for tests with field collected organisms should have been further assessed points based the lack of information on appropriate size/age/growth phase of organisms (3), no prior contaminant exposure (4), organisms fed 2 h before solution renewal or not fed in acute test (3), and organisms properly acclimated and disease free prior to testing (1). Likewise, the Documentation Ratings for sublethal behavioral responses should have been assessed points based the lack of information on control type (8). Tests with field collected organism should have also been assessed Documentation Ratings points based on the source (5) and age/life stage/size/growth phase (5). These deductions would lower the Documentation scores by 18 points from 85 to 67 and Acceptability scores would be lowered by 25 points from 86 to 71 for some test results. Given these concerns, the Draft Report authors should reconsider the RR ranking of data from Weston and Lydy (2014) and other similar studies.

GC-3) The Draft Report does not provide a description of the cutoff scores for the R, L, and N rankings. Please provide a reference to TenBrook et al. (2009; Table 3.11), which used results for chlorpyrifos to set cutoffs for all pesticides, if this approached was used. It would also be helpful to discuss the applicability of rating Fipronil toxicity data as “R” for reliability (i.e., 74-100 was used in TenBrook et al, 2009) based on a review of chlorpyrifos.

GC-4) It is not appropriate to include sublethal toxicity data in the determination of acute WQC when the linkage has not been clearly made with survival, growth or reproduction. The Draft Report should include a discussion and rationale linking these sublethal responses with survival if they are to be used in acute WQC derivation. This would be consistent with previous responses to comments (TenBrook and Tjeerdema, 2009).

“...6 very important and therefore heavily weighted requirements (endpoints linked to survival growth or reproduction, conducted in freshwater, chemical of at least 80% purity, family in North America, report a numerical toxicity values or one is calculable, report a control

1 http://www.waterboards.ca.gov/waterrights/water_issues/programs/bay_delta/deltaflow/docs/exhibits/sac_rcsd/srcsd_exh2a.pdf

http://www.waterboards.ca.gov/waterrights/water_issues/programs/bay_delta/deltaflow/docs/exhibits/sac_rcsd/srcsd_exh2a.pdf


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treatment/response). If a study does not meet one of these requirements the score would be reduced by 15 points. By this system only studies that have all 6 of these requirements will be used in the SSD and calculation of criteria. The lack of one or two of these important parameters would make the study available only for supplemental information (not used in the SSD calculation), and a lack of 3 more of these parameters excludes the study from the whole criteria derivation process.” Response to comment 6-5. Page 31. In. TenBrook and Tjeerdema (2009).

UC Davis Reponses to Comments 7-5 and 7-6 agree that studies that do not report survival, growth, or reproduction endpoints should not be used as primary lines of evidence to generate WQC.

“COMMENT 7-6: Studies that do not report toxicological endpoints of survival, growth, or reproduction (e.g., standard EPA endpoints) should not be used to generate water quality criteria.

RESPONSE TO COMMENT 7-6: UCD See response to comment 7-5.

RESPONSE TO COMMENT 7-5: ... A study using an impure chemical standard would loose[sic] 15 points (out of 100) and studies with a relevance score of 70-90 are only to be used as supplemental information. So this instance (and those described in comments 7-6, 7-7, 7-8) would receive relevance scores of 85 and would therefore be unacceptable for criteria derivation by this method.”

EPA has been clear in describing acute toxicity as being based on lethality within a relatively short time period (USEPA 2002). Regarding acute toxicity endpoints, an expert panel stated, “The results of these tests usually measure lethality, an obvious and easily measured effect, often expressed as the concentration lethal to 50% of the test organisms.” (Chapman 1996). It is also overly conservative to use a sublethal response measured over a 2-4 day exposure as the basis for an acute WQC that applies to a one-hour average concentration.

GC-5) It is questionable to use toxicity data for sediment dwelling organisms (i.e., Chironomidae) as a primary line of evidence for deriving WQC. These organisms are highly appropriate for determining SQC and would be helpful secondary lines-of-evidence to validate a proposed WQC. If the next most sensitive water-column species was selected for the acute WQC derivation of Fipronil-sulfide (Isoperla sp. with and LC50 of 0.0945 µg/L), then the final acute criterion would be 5.9 ng/L compared to 0.58 ng/L calculated using the sediment-dwelling midge. This alternative acute WQC would be applicable to a one-hour average concentration and would be sufficiently protective of aquatic life.

GC-6) The UC Davis Sediment Method assessment factor approach requires a benthic crustacean as one of the acute data in order to use the Assessment Factor (AF) procedure (section 3.5.2, Fojut et al. 2014), as 'typically available and likely to be relatively sensitive.’ However, the available data indicate that diptera of the family Chironomidae are much more sensitive to Fipronil and its degradates than crustaceans. If the sediment-dwelling larvae are to be used in developing WQC then it would seem that acute data from an insect larvae from the family Chironomidae would be an appropriate requirement for deriving criteria for Fipronil and its degradates.

GC-7) Alternative curve fitting should be explored for these data. Figure 6 shows one interpretation of acute toxicity data for Fipronil-sulfone, where the 5th and 1st percentiles are calculated far beyond the range of available data where uncertainty is very high. The fitted curve does not appear to be a best fit and drives overly conservative WQC. It would be more appropriate and increase the scientific validity to assess multiple models to fit the SSD and then select the regression with the best fit (e.g., using the


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Anderson-Darling statistic2). The UCD method of sequential testing for a regression that meets some minimum requirements does not result in a best-fit. It would also be extremely helpful to add confidence intervals for the curve on all SSD figures to more accurately depict the uncertainty in these calculations.

GC-8) The method, including the use of conservative AFs to drive down the derived WQC in the absence of data, has produced draft WQC that are generally below MDLs for most of these parameters for 2 of 3 California Labs (Exhibit 1). Those with NPDES permits in the Central Valley could have WQOs adopted into their permits based on these WQCs that will effectively be at the limit of detection.

Although not recognized in the draft Fipronil criteria derivation, quantitation limits may have an impact on the ability of agencies and dischargers to achieve TMDL goals. The ability to detect concentrations below one ppt (less than one ng/L) in a complex matrix such as effluent is even more challenging than detecting these low concentrations in a clean matrix and has not yet been demonstrated. Responses to previous comments have indicated that the recommended criteria are developed independent of considering how they would be implemented and that it is up to the CVRWQCB to determine how they would be adopted and implemented. However, now that other WQC that also fall below achievable quantitation limits have been (e.g., the final 2015 esfenvalerate WQC), were developed for use by CVRWQCB staff this comment should be addressed.

Exhibit 1. Laboratory MDLs and RLs associated with Fipronil and its degradates

Pesticide Fipronil (ng/) Fipronil-sulfide

(ng/L) Fipronil-sulfone

(ng/L) Acute WQC 14 0.58 1.3

Chronic WQC 2.2 0.13 0.17 Lab 1 MDL 0.5 0.5 0.5

RL 1 1 1 Lab 2 MDL 2.9 1.8 3.5 Lab 3 MDL 3 2 2 Notes:

Water Quality Criteria were not developed for Fipronil-desulfinyl and Fipronil-carboxamide due to a lack of toxicity data. MDL = method detection limit ng/L = nanogram per liter RL = reporting limit Lab 1 method - SW846 8270 Mod (GCMS-NCI-SIM) Lab 2 method - USGS TM-5-C2 (GC/MS) Lab 3 method - USGS O-1126-02 Shaded values indicate where the lab MDL or RL is insufficiently low to characterize WQC exceedance

GC-9) The text in Section 12.2 (page 35) indicates that California Department of Fish and Wildlife have used the EPA method for calculating WQC in cases where only seven of the eight requirements are met when the missing taxon are known to be insensitive. It would be helpful if the data are discussed supporting a conclusion that the missing taxa (i.e., Phylum other than Arthropoda or Chordata such as Rotifera, Annelida, or Mollusca) are insensitive. If data do not support a conclusion that these missing taxa are insensitive then the consequences of this data gap on the WQC should also be discussed.

2 Anderson, T. W.; Darling, D. A. (1952). "Asymptotic theory of certain "goodness-of-fit" criteria based on stochastic processes". Annals of Mathematical Statistics. 23: 193–212. doi:10.1214/aoms/1177729437.

https://en.wikipedia.org/wiki/Digital_object_identifier

https://dx.doi.org/10.1214%2Faoms%2F1177729437


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GC-10) Fojut et al. (2014) is currently only available as a draft from the referenced State Water Resources Control Board website. The reference to Fojut et al. (2014) in the Fipronil Water and Sediment Quality Criteria Draft Report should be updated to reflect this document is a draft and it would be helpful to indicate which Phase (I, II, or III) report is specifically referenced. It seems that the Phase II report is the one referenced. The appropriateness for SQC to be derived based on draft guidance that has not considered public review should also be made clear to risk managers. Alternatively, if the documents have been finalized then it would be very helpful to reviewers if the final versions could be posted.

Editorial comments

There are many cases where tables are not referenced in the text when numbers from the tables are discussed. This makes it difficult for the reader to find information quickly and it would be helpful to include. For example, Section 8.2.2 would benefit from a reference to Table 20 for the MATC value (0.16 µg/g OC) provided. Section 10.1 would benefit from references to Tables 14 and 21 (which have supplemental data), as well as other tables (with RR data) when used.

Page vii, List of Tables – Tables 21 and 22 are missing from the list of tables. Please add the following:

Table 21 Supplemental sediment toxicity values excluded from Fipronil/degradates BSQC derivation (found on page 31)

Table 22 Threatened, endangered, or rare species predicted values by Web-ICE (found on page 32)

Figure 2 is not referenced in the text. It could be referenced in the third paragraph of the introduction on page 1.

Tables 1 and 2 are not referenced in the text descriptions preceding the tables.

, Section 5 – The RR sediment studies are summarized in Tables 15-20, not 15-21.

Page 10, Section 5 – Tables 13, 14, and 21 are not referenced in the text.

Page 10, Section 6 – Define SMAV and SMCV on first use (2nd paragraph under aqueous data).

Page 10, Section 6 – There is an error message showing up in the second paragraph that says “(Error! Reference source not found.-7)”.

Page 14, Section 7.1.2 – Add a reference to Table 4 when discussing the EC50 value (0.0093 µg/L).

Page 15, Section 7.1.3 – Reference to Figure 3 in the first paragraph is incorrect. This should reference Figure 5.

Page 17, Section 7.1.4 – Reference Table 6 when discussing the available fish data.

Page 18, Section 7.2.1 – Reference Table 9 for the MATC value (14 µg/L) provided.

Page 19, Section 7.2.2 – Reference Table 10 for the MATC value (17 µg/L) provided.

Page 20, Section 7.2.3 – Reference Table 11 for the MATC value (0.97 µg/L) provided. Appendices The page numbering in all the appendices is “C1, C2, C3, etc...” but it would be more helpful if changed to a unique page numbering for each appendix. For example, Appendix A could be A1, A2, A3, etc...and Appendix B could be B1, B2, B3, etc...


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Appendix A Pages C129-130, Fipronil – data for Aedes aegypti reported from Ali 1998 are not listed in Table 14, though study is rated as RL – 95% CI LC50=0.00154 (0.00143-0.00165) µg/L - survival

Pages C157-158, Fipronil Sulfide – data for Cheumatopsyche brevilineata reported from Iwafune 2011 are not listed in Table 14; study rated as LL – 95% CI EC50=0.052 (0.042-0.059) µg/L – immobilization

Pages C159-160, Fipronil – data for Cheumatopsyche brevilineata reported from Iwafune 2011 are not listed in Table 14; study rated as LL – 95% CI EC50=0.133 (0.112-0.148) µg/L – immobilization

Pages C161-162, Fipronil sulfone – data for Cheumatopsyche brevilineata reported from Iwafune 2011 are not listed in Table 14; study rated as LL – 95% CI EC50=0.066 (0.054-0.078) µg/L – immobilization

Pages C163-164, Fipronil desulfinyl – data for Cheumatopsyche brevilineata reported from Iwafune 2011 are not listed in Table 14; study rated as LL – 95% CI EC50=0.177 µg/L – immobilization; Additionally, there is a mistake in the range of confidence interval data. The table has 0.054-0.078 µg/L, but that is for Fipronil sulfone (above) and cannot be the range for a 95% CI of 0.177 µg/L.

Pages C165-166, Fipronil carboxamide – data for Cheumatopsyche brevilineata reported from Iwafune 2011 are not listed in Table 14; study rated as LL – 95% CI EC50=4.95 (3.23-26.0) µg/L – immobilization

Pages C167-168, Fipronil – data for Cheumatopsyche brevilineata reported from Yokoyama 2009 are not listed in a Table 14; study rated as LL – 95% CI LC50=0.153 (0.142-0.164) µg/L – survival

Page C167 – Typographical error for Test vessels randomized? Result - “Not repoted” should be “Not reported”.

Page C169-170, Fipronil – data for Chironomus crassicaudatus reported from Ali 1998 are not listed in a Table 14; study rated as RL – 95% CI LC50 0.00042 (0.00032-0.00052) µg/L – survival.

Pages C195-196, Fipronil sulfide – data for Daphnia magna reported from Iwafune 2011 are not listed in Table 14; study rated LL – 95% CI EC50=28 (22.6-33.8) µg/L – immobilization.

Page C228 – Typographical error - “P. clarkia” should be “P. clarkii”.

Appendix B Page C36-39, Fipronil – data shown for Hyalella azteca from Picard (2015) do not match the H. azteca data presented in Table 15. This appears to be caused by the number of significant figures listed in Table 15 compared to the write up in Appendix B. Table 15 has the LC/EC50 as 13.33 (11.48-15.19) µg/g OC, whereas the LC50 on Page C38 of Appendix B has 13 (11-15) µg/g OC. Please correct this inconsistency.

References

American Society of Testing and Materials (ASTM). 2010. Standard Test Method for Measuring the Toxicity of Sediment-Associated Contaminants with Freshwater Invertebrates Designation: E1706 − 05 (Reapproved 2010).

Chapman, GA. et al. (1996). Discussion synopsis, methods and appropriate endpoints. Chapter 3 In: Whole Effluent Toxicity Testing: An Evaluation of Methods and Prediction of Receiving System Impacts.

Fojut TL, Vasquez M, Trunnelle KJ, Tjeerdema RS. 2014. Methodology for Derivation of Pesticide Sediment Quality Criteria for the Protection of Aquatic Life, Report prepared by the University of California Davis for the Central Valley Regional Water Quality Control Board. Available at:


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http://www.swrcb.ca.gov/rwqcb5/water_issues/tmdl/central_valley_projects/central_valley_pesticides/sediment_quality_criteria_method_development/index.shtml

McNamara PC. (1990b) (M & B 45950)-Acute toxicity to daphnids (Daphnia magna) during a 48-hour flow-through exposure. Springborn Laboratories, Inc., Wareham, Massachusetts.

Pennington, D.W. 2003. Extrapolating ecotoxicological measures from small data sets. Ecotoxicology and Environmental Safety. 56:238-250.

TenBrook and Tjeerdema. 2009. Responses to Public Comments. Phase I: Review of Existing Methodologies. Phase II: Methodology Development and Derivation of Chlorpyrifos Criteria of the Methodology for Derivation of Pesticide Water Quality Criteria for the Protection of Aquatic Life in the Sacramento and San Joaquin River Basins.

TenBrook, P.L., A.J. Palumbo, and R.S. Tjeerdema. 2009. Methodology for Derivation of Pesticide Water Quality Criteria for the Protection of Aquatic Life - Phase II, Methodology Development and Derivation of Chlorpyrifos Criteria.

USEPA. 1985a. Guidelines for deriving numerical national water quality criteria for the protection of aquatic organisms and their uses, PB-85-227049, section III-B-1. US Environmental Protection Agency, National Technical Information Service, Springfield, VA. URL< http://www.waterboards.ca.gov/waterrights/water_issues/programs/bay_delta/deltaflow/docs/exhibits/sac_rcsd/srcsd_exh1w.pdf>

USEPA. 1985b. Methods for Measuring the Acute Toxicity of Effluents to Freshwater and Marine Organisms, EPA-600/4-85-013. US Environmental Protection Agency, Office of Water, Washington DC.

USEPA. 2002. Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms, EPA-821-R-02-012. US Environmental Protection Agency, Office of Water, Washington DC.

USEPA. 2006. Memorandum: Review of Aquatic Invertebrate Toxicity Studies for Fipronil. Available at DM # 3926590.

Weston, D.P. and M. Lydy. 2014. Toxicity of the insecticide Fipronil and its degradates to benthic macroinvertebrates of urban streams. Environmental science & technology. 48(2):1290-1297.



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