UNITED STATESENVIRONMENTAL PROTECTIONAGENCY WASHINGTOND.C., 20460
OFFICE OF PREVENTION, PESTICIDESAND TOXIC SUBSTANCES PC Code: 056502 DPBarcode: 291271 Date: March 22,2010 MEMORANDUM Subject: 2008 Science Advisory Panel Meeting Follow Up: Assessment of the Bioaccumulation and Long-Range Transport Potential (LRTP) and of Pentachloronitrobenzene (PCNB) and Associated Ecological Risks To: Jill Bloom, Risk Manager Reviewer Pesticide ReregistrationDivision From: Kristina Garber,M.S.,Biologist Environmental Risk Branch N EnvironmentalFate and Effects Division (7507P) Reviewed by: Thomas Steeger,Ph.D., Senior Biologist Cheryl Sutton,Ph.D., Environmental Sci 

### R. David Jones, Ph.D. Senior Agronomist 

### (f Environmental Risk Branch

### N Keith Sappington, M.S., SeniorBiologist hdk

## sPfi .y4n (Tmr 

# fi33

. 

## ?/, Environmental Risk Branch V EnvironmentalFate and Effects Division (7507P) Approved by: Elizabeth Behl, M.S., Branch Chief Environmental Risk Branch IV 

# bM 

# ~4 JCN) 7-23

## -la EnvironmentalFate and Effects Division (7507P) Attached please find an assessment of the bioaccumulation potential of PCNB and its degradates, and contaminants and their associated ecological risks. Also included is an assessment of the long-range transport potential of PCNB and its degradates. PCNB and its degradates and contaminants are considered sufficiently persistent and likely to bioaccumulate in aquatic food chains to represent a chronic risk to mammals that consume aquatic organisms. In addition, PCNB is expected to move through long-range atmospheric transport to considerable distances from its site of application. Technical PCNB contains several contaminants, including hexachlorobenzene, polychlorinated dibenzodioxins and polychlorinated dibenzofurans, which are listed under the StockholmConvention as Persistent Organic Pollutants (POPS). The weight of evidence suggests that PCNB, when considered with its residues and contaminants of concern, is a persistent, bioaccumulative, toxic chemical (PBT).

Page 1of 70

# Assessment of the Bioaccumulation and Long Range Transport Potential of Pentachloronitrobenzene (PCNB) and Associated Ecological Risks

Prepared by: Kristina Garber, M.S., Biologist Contribution by: Faruque Khan, Ph.D., Senior Physical Scientist Reviewed by: Thomas Steeger,Ph.D., Senior Biologist Cheryl Sutton,Ph.D., Environmental Scientist R. David Jones, Ph.D. Senior Agronomist Keith Sappington,M.S., Senior Biologist Elizabeth Behl, M.S., Branch Chief U. S,Environmental ProtectionAgency OfficeofPesticide Programs Environmental Fate and Effects Division Environmental Risk BranchIV 1200 PennsylvaniaAve., NW Mail Code 7507P Washington, DC 20460

March22,2010

Page 2 of 70Executive Summary The enviranmental fate and ecological risk assessment written in support of the Reregistration Eligibility Decision (RED) for PCNB (finalized in 2005) provided evidence that PCNB has the characteristics of a Persistent,Bioaccumulative and Toxic (PBT) chemical. The risk assessment also concluded that PCNB has the potential for long-range transport to non-target sites. In October 2008, the Environmental Fate and Ecological Effects Division (EFED) met with the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP) to discuss approaches for evaluating pesticides with attributes characterized as PBT (EPA, 2008). This assessment integrates available data on PCNB and its degradates in the context of recommendations from the SAP. The current assessment refines the previous conclusions relevant to the PBT characteristics of PCNB and its degradates. This is accomplished using the methods discussed during the 2008 SAP meeting. Specifically, this assessment has 4 main objectives: 1)to investigate the impact of assumptions of the aquatic exposuremodel used by EPA (EXAMS) for persistent chemicalsand the influence of those assumptionson estimated exposure and risk of PCNB; 2) to characterize the bioaccumulation potential of PCNB, its degradates, and its contaminants in aquatic systems and subsequent risks associated with each of these compounds; 

### 3) to characterize the bioaccumulation potential of PCNB and its degradates in terrestrial systems and subsequent effects on risks; and 4) to investigate the long-range transport potential of PCNB and its degradates. The results ofthis assessment indicate that inclusion ofpesticide burial, alterationof equilibrium partitioning of PCNB between aqueous and sorbed phases (on entering soil particles) and mass transfer between the water column and the benthic compartment using the EXAMS model do not alter the risk conclusions of EPAYs previous ecological risk assessment for PCNB. Therefore, consistent with the 2005 assessment, current uses of PCNB poses acute and chronic risk to freshwater fish and invertebrates,acute risk to estuarinelmarine invertebrates, and chronic risk to estuarinelmarine fish and invertebrates. This assessment investigated in greater detail the propensity for PCNB and its degradates to bioaccumulate in aquatic organisms. Using available bioconcentration data for PCNB and modeling results (KABAM), results indicate that PCNB and its degradates are likely to accumulate in tissues of aquatic organisms. Modeling further demonstrates that mammals consuming aquatic organisms have the potential to experience adverse effects due to chronic exposuresto PCNB and its degradates in aquatic forage items from registered uses of PCNB on turf, cabbage, peanuts, cotton and potatoes. Use of PCNB on turf poses a risk of chronic effects to birds, amphibians and reptilesconsuming aquaticorganisms. Technical PCNB contains several contaminants, including hexachlorobenzene (HCB), polychlorinated dibenzodioxins(PCDDs) and polychlorinated dibenzohrans (PCDFs), which are listed under the Stockholm Convention as Persistent Organic Pollutants (POPS). HCB, PCDDs and PCDFs are expected to bioaccumulate in aquatic systemsto levels that pose risk of chronic effectsto mammals consuming aquatic organisms.

Page 3 of70In previous ecological risk assessments of PCNB, bioaccumulation of PCNB and its degradates in terrestrial organisms was not considered. Based onthe estimated octanol-air and ocjtanol-water partition coefficientsfor PCNB and its degradates, PCNB and its degradates have the potentialto bioaccumulate in terrestrial ecosystems. Estimated concentrations ofPCNB and its degradates in earthworms are two orders ofmagnitude higher than concentrations in soil,indicating that PCNB and its degradates can accumulate in soil-dwelling organisms inhabiting fields tfeated with PCNB. Available studies with terrestrial plants (i.e., crops) and animals indicate that PCNB is metabolized by terrestrial organisms; however, all metabolites that were identified were polychlorinated phenyl compounds, which are oftoxicological concern. At this time, OPP has no tool available to assessbioaccumulation in terrestrial food webs (beyond earthworms). Thbrefore, the extent of bioaccumulation of PCNB in terrestrial ecosystems cannot be quantified by EFED at this time, and risks to terrestrial animals resulting from terrestrial bioaccumulation cannot be precluded. In addition to bioaccumulation, this assessment considers the ability of PCNB and its degradates to move to non-target sites via long-range transport. The volatility of PCNB coupled with its likely persistence in the atmosphere allow for potential long-range atmospheric transport of PCNB. Detections of PCNB in the atmosphere over areas in which the pesticide was not used provide evidence of the possibility for long-range transport. Modeling indicates that PCNB has comparable or higher long-range transport potential compared to chemicals that are known to move via this route oftransport.

Page 4 of 70

### Table of Contents
1



### .Introduction



### ................................................................................................................................. 3 1


## .1.Purpose of Assessment



### ........................................................................................................ 3 1.2.PCNB Use Characterization



### ............................................................................................... 3 

### 1.3.PCNB Residues of Concern



### ................................................................................................. 3 1.4. CharacterizationofEnvironmental Persistence



### ................................................................... 3 1.5.Characterization of Effects to Non-target Animals



### ............................................................. 3 1.5.1.Aquatic Animals



### ........................................................................................................... 3 1.5.2. Terrestrial Animals



### ...................................................................................................... 3 1.6.Risk Conclusions from Ecological Risk Assessment Supporting RED



### ............................ 3 2



### .Accumulation of PCNB and its Degradatesin Aquatic Systems



### ............................................... 3 2.1. Consideration of Pesticide Burial inAquatic Exposure Modeling



### ...................................... 3 2.2. Equilibrium between Sediment and Water Column Concentrations



### ................................... 3 2.3. Mass Transfer ofPesticide fiomWater into Sediment



### ........................................................ 3 3


## .Bioaccumulation of PCNB and its Degradates and Contaminantsin Aquatic Organismsand Associated Ecological Risks



### ........................................................................................................... 3 

### 3.1. Bioconcentration Factors (BCFs) ofPCNB and its Degradates



### .......................................... 3 3.1



### .1.Estimated BCFs Using Modeling



### ................................................................................. 3 3.1.2



### .Empirical BCFs



### ............................................................................................................. 3



### ....................................................................... 3.2.Metabolism of PCNB in Aquatic Organisms 3



### ........................................................................................... 3.3. PCNB Residues in Fish Tissues 3 3.3.1.Monitoring Data



### ............................................................................................................ 3 3.3.2. Estimated Concentrations of PCNB and its Degradates in Tissues ofAquatic Organisms



### ............................................................................................................................... 3 3.3.3. Comparison of Field Measured and Estimated Concentrations of PCNB and its



### ...................................................................................................... degradates in Fish Tissues 3



### ............ 3.3.4. Estimated Concentrations of ContaminantsinTissues of Aquatic Organisms 3 3.4. Risks to Mammals, Birds, Terrestrial-phase Amphibians and Reptiles Consuming Aquatic



### ................................................................................................................................... Organisms 

### 3 3.4.1. Chronic Risks to Mammals fiom PCNB and its Degradates



### ........................................ 3



### ........................................................... 3.4.2. Chronic Risks to Mammals from Contaminants 3 3.4.3. Chronic Risks to Birds, Terrestrial-phase Amphibians and Reptiles from PCNB and its Degradates



### .......................................................................................................................... 3 3.4.4. Chronic Risks to Birds, Terrestrial-phase Amphibians and Reptiles from



### .......................................................................................................................... Contaminants 3 4



### .Bioaccumulation ofPCNB and its Degradatesin Terrestrial Organisms and Associated Risks 

### 3 4.1. Accumulation of PCNB and its Degradates in Soil



### ............................................................. 3 4.2. Bioaccumulation Potential



### ................................................................................................... 3 4.3. Metabolism of PCNB in Terrestrial Organisms



### .................................................................. 3 4.4. Risks to Mammals, Birds, Terrestrial-phase Amphibians and Reptiles Consumidg Earthworms



### ............................................................................................................................... 3 5



### .Long Range Transport Potential (LRTP) ofPCNB and its Degradates



### ..................................... 3 5.1



### .Volatilization Data



### ............................................................................................................... 3 5.2. Monitoring Studies



### ............................................................................................................... 3 5.3. Modeling Long-Range Transport Potential



### ......................................................................... 3

Page 5 of 70

### . 

### ......................................................................................................... 6 Summary and Conclusions 

### 3



### ......................................................................................................................... 7



### .References Cited 

### 3



### . 

### ..................... Appendix A Octanol-waterPartitioningCoefficients ofPCNB and its Degradates 3



### . 

### ... Appendix 

### B Open literaturereview summaries for bioconcentration studies involving PCNB 

### 3 Appendix C


## .Use offugacity approachto estimate pesticide concentrationsin earthworms



## . located on treated fields



### .............................................................................................................. 3

Page 6 of 70

### 1. Introduction 1.1,Purpose of Assessment The environmental fate and ecological risk assessment written in support of the Reregistration Eligibility Decision (RED) for PCNB (finalized in 2005; DP Barcode D291276), provided evidence that PCNB has the characteristics of a Persistent, Bioaccumulative and Toxic (PBT) chemical. The risk assessment also concluded that PCNB has the potential for long-range transport to non-target sites.
In October 2008, the Environmental Fate and Ecological Effects Division (EFED) of the U.S. Environmental Protection Agency's Office of Pesticide Programs (OPP) met with the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP) to discuss current and proposed approaches for evaluating pesticides with attributes characterized as PBT. The background document provided to the SAP entitled "Methodsfor AssessingEcologicalRisks of Pesticides with Persistent, Bioaccumulative and Toxic Characteristics" (USEPA 2008a), described current approaches and recent improvements to the tools, methods and data which have been used to evaluate the ecological risks ofpesticides with PBT-like characteristics. EPA requested that the SAPprovide input on whether the EPA's approaches to addressing PBT issues and its use of additional methods are consistent with the available science and are appropriate for further development and integration into the EPA's risk assessment process. Overall, the SAP agreed that the EPA identified many of the challenging issues related to ecological risk assessments of pesticides with PBT characteristics and long-range transport potential (LRTP). The SAP indicated that the refinements proposed in the White Paper represented "a leap forward" for the EPA and that EPA's proposed refinements are rooted in science. The purpose ofthis assessment is to further refine EPA's conclusions on the PBT characteristics of PCNB and its degradates that were made in the original ecological risk assessment written in support ofthe reregistrationdecision (DP Barcode D291276). This assessment uses the methods described in the EPA's white paper (USEPA 2008a), with consideration of the comments provided by the SAP and has 

### 4 main objectivesl) to investigatethe impact of assumptions ofthe aquatic exposure model used by EPA (EXAMS) for persistent chemicals and the influence of those assumptions on estimated exposure and risk of PCNB; 2) to characterize the bioaccumulation potential of PCNB, its degradates and its contaminants in aquatic ecosystems and subsequent risks associated with each of these components; 

### 3) to characterize the bioaccumulation potential of PCNB and its degradates in terrestrial ecosystems and subsequent risks; and 4) to investigate the long range-transport potential of PCNB and its degradates. 1.2. 

### PCNB Use Characterization PCNB is a contact fungicidethat provides preventative and residual protection against soil-borne diseases. The environmental fate and ecologicalrisk assessment chapter written in support ofthe RED (DP Barcode D291276) for PCNB focused on the five major uses, i.e., turf, peanuts, cole crops (e.g. cabbage,broccoli),potatoes and cotton. At the time the assessmentwas written, these uses accounted for over 86% of the national usage ofPCNB.

Page 7 of70The current assessment was developed based on maximum label application rates for PCNB use on turf, peanuts, cotton, potatoes and cabbage that were defined in the ecological risk assessment chapter for PCNB (DP Barcode D291276). Since the ecological risk assessment chapter was completed, the EPA determined that the majority of these uses were ineligiblefor reregistration. According to the RED, the only uses of PCNB that are eligible for reregistration include: cole crops (for control of clubroot), commercial production of flowering bulbs and seed treatments (USEPA 2006). 

### 1.3. PCNB Residues of Concern PCNB has several environmentaldegradates and contaminants ('present in technical PCNB) that are of toxicological concern. Degradates and contaminants are of toxicological concern when their structure includes a polychlorinated phenyl ring. Environmental degradates ofPCNB that were identified in the environmental fate and ecological risk assessment chapter for the RED (DP Barcode D291276)include: pentachloroaniline (PCA), pentachlorothioanisole (PCTA), pentachlorobenzene (PCB; also present as a contaminant), pentachlorophenol (PCP), pentachlorothioanisole sulfoxide(PCTASO), and pentachlorothioanisole sulfone (PCTAS02). This assessment considers exposures and risks of PCNB and all of its environmental degradates that contain a polychlorinated phenyl ring; in other words, all of the degradates listed above. Available toxicity data for PCNB and its degradates are provided below. Based on environmental fate studies available at the time the environmental fate and ecological risk assessment chapter was written, three major degradatesofPCNB were identified:PCA, PCTA and PCB (Figure 1).

PCNB PCA PCTA PCB Figure 1. Structures of PCNB and its major environmental degradates. Technical PCNB contains several manufacturing impurities, which are termed "contaminants" in this assessment. These include hexachlorobenzene (HCB), PCB, polychlorinated dibebodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). HCB, PCDDs and PCDFs ark currently listed under the Stockholm Convention as Persistent Organic Pollutants (POPS). In August 2010, PCB, which is a degradate and a contaminant ofPCNB, will alsobe listed as a POP.
Page 8 of70In EFEDYs environmental fate and ecological risk assessment chapter for PCNB, HCB and PCB were identified as contaminants. For HCB and PCB, the EPA allows a maximum of 500 ppm and 100 ppm, respectively, in technical PCNB'. According to samples recently (2010) analyzed by the OPP Biological and Economic Assessment Division and historical data reported in the Canadian Reevaluation Decision for Quintozene (i.e., PCNB; Health Canada 2009), polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are present in technical grade PCNB (Table 1). 

### An assessment of data previously submitted to the EPA had indicated that dioxins were expected to be below the EPA-specified Limits of Quantitation (USEPA 2004~). The reasons for the differences in residues measured by EPA in 2010 and Canada in 2009 are currently being exploredby EPA.

To roughly estimate potential environmental loading of PCDDs and PCDFs, the EPA estimate of national usage of PCNB from 1990-2000 is 1.825 million Ibs per year (DP Barcode D291276). Using the reported levels of contaminants in Table 1, this translates to an annual application of approximately between 0.5 and 4 Ibs of PCDDs and PCDFs. The contaminants PCDDs and PCDFs were not considered in the 2005 ecological risk assessment chapter for PCNB; however, in light of the occurrence in recent reports they are included in this assessment. Chemicals such as PCDD and PCDF are considered to be persistent, bioaccumulative and are not metabolized by mammals (Van Den Berg et

### al. 2006). In general, considering the Log 

### &, values of PCDDs and PCDFs (Log 

### &, range: 7.9-9.5) relative to those of PCNB and its degradates (5.0, see Appendix A for details on how this value was derived), these contaminants would be expected to bioaccumulateto a greater extent than PCNB and its degradates. Therefore, this assessment considers the bioaccurnulation of these contaminants in aquatic systems separately from PCNB and its degradates. 1.4. Characterization ofPCNB Environmental Persistence PCNB is characterized as stable to hydrolysis (MRIDs 40865301, 40972601) and photodegradation on soil (MRIDs 4 1004801,4 17 13201).Available aqueous photolysis half-lives for PCNB were 1.1 (MRID 42336201) and 2.5 days (MRIDs 42606210, 42606202). Available 

## ' Personal communicationwith Jill Bloom. Page 9 of 70aerobic soil metabolism half-lives for PCNB combined with its degradates were 983 and 1052 days (MRIDs 429 11902, 41384501, 4173202, 42112801).Anaerobic soil metabolism data yield a half-life of 334 days for PCNB combined with its degradates (MRIDs 41203602, 42094401, 41384301, 41686001, 41713202, 421 12802). Aquatic metabolism data for PCNB are not available. Based on available data, PCNB and its degradates, considered together, are considered likely to be persistent in the environment. Although the primary route of degradation for PCNB is through aqueous photolysis, the ideal conditions for this route of degradation (i.e.,clear, shallow water) is limited under natural conditions because runoff water tends to be turbid and incident light in surface water bodies is attenuated with increasing depth of water. PCNB is a moderately volatile compound that can be expected to dissipate through volatilization. Volatilization was observed in the laboratory metabolism studies cited above; however the rate of volatilization in these studies would be expected to be different than that in the field. Therefore, volatilization was factored out of the metabolism studies by adding the volatilized residues back into the estimates of total residues. Volatilization of PCNB and its deigradates is expected to represent a relevant route of dissipation; however, the overall persistence of PCNB and its degradates in the air isunknown. 1.5. Characterization ofEffects to Non-target Animals 1.5.1.Aquatic Animals On an acute exposure basis, PCNB and several of its degradates are considered highly toxic (defined as 100 5 LCs0<lo00 pg1L) to freshwater fish and invertebrates and very highly toxic (defined as LC50 400pglL) to estuarinelmarine invertebrates. Available acute toxicity data for fish and aquatic invertebrates exposed to PCNB and its degradates indicate that some of the degradates are of similar or greater toxicity to aquatic animals. Available 96-h LCSo values for 3 species of fish exposed to PCNB range 100-7900 pg/L. LC50 values for PCA, PCB and PCP range 56-800 pg/L for seven species of fish (Table 2). For aquatic invertebrates, ECsovalues range 12-770 pg/L for acute exposures to PCNB. Acute LCsovalues for aquaticinvertebrates exposed to PCA, PCB and PCB are similar to PCNB, with LCsovalues ranging from 50 to 450 pg/L for these degradates (Table 2). Toxicity data were not available for acute exposures of aquatic animals to PCNB degradates PCTA, PCTASO, and PCTAS02. 

### In order to characterize the relative toxicity of PCTA, PCTASO, PCTAS02to PCNB and PCA, PCB and PCP, the predictive tool ECOSAR v. 0.99h was run to estimate 96-h LCs0values for fish and aquatic invertebrates. ECOSAR estimates of acute toxicity indicate that PCTA may be of similar or greater toxicity compared to PCNB. ECOSAR estimatesindicate that PCTASO and PCTASOzmay be of lesser toxicity compared to PCNB.

Page 10of70Table 2. Summary of

### 96-h LC50 (units in pg/L) estimatesfor fish as calculated

### by ECOSAR and measured in toxicitv tests.

Toxicity data are available in the open literature involving exposures of aquatic animals to HCB and to PCDDs and PCDFs (identified using ECOTOX). These data are not discussed fhther in this assessment since effects of direct exposures of fish and aquatic invertebrates to HCB and PCDDs and PCDFs are not considered. 

### 1.5.2.Terrestrial Animals Mortality from acute exposures is not considered to be of concern in this risk assessment, since PCNB is practically non-toxic (defined as LD5~>2000 mag bw) to birds and mammals on an acute oral exposurebasis (MRIDs406 18001,40652602,40652603,41443101).
For chronic effects, the toxicity endpoint isthe no observed adverse effectlevel (NOAEL) or the no observed adverse effect concentration (NOAEC). The most sensitive toxicity endpoints available from surrogate test species are used to estimate treatment-related effects on chronic assessment endpointsof impaired growth, survival and/or reproduction. Chronictoxicity data are available only for the parent compound; no data are available to define the chronic toxicity of PCNBYs degradates to birds and mammals. Therefore, it is assumed that the toxicity of the degradatesto birds and mammals is equivalent to that of theparent PCNB based on the similarity in parentldegradate chemical structures and toxicity to aquaticvertebrates and invertebrates. Chronic toxicity data are available for Northern bobwhite quail (Colinus virgindanus) and mallard duck (Anas platyrhynchos) exposed to PCNB. In an avian reproduction study, adult mallard ducks exposed to dietary concentrations of PCNB as low as 1200mag-diet (LOAEC) exhibited significantly lower body weights compared to controls. The resulting NOAEC for mallard ducks was 600 mag-diet (MRID 41332802). In an avian reproduction study with northern bobwhite quail, the LOAEC was also 1200mglkg-diet, based on a decreased Survival of offspring (specifically, a reduction in the number of 14-d survivors as a perGentage of hatchlings). The resulting NOAEC for northern bobwhite quail was also 600 mglkg-dfet(MRID 41332801). These data are used as a surrogate for non-target birds as well as terrespial-phase amphibians and reptiles; in the absence of data to the contrary, PCNB degradates arepresumed to have similar toxicityto that oftheparent compound.

Page 11of70Chronic toxicity data are availablefor laboratory rats (Rattusnorvegicus) exposed to PCNB. In a 2-generation study with rats (MRID 41918701), decreased body weight was observed in parents and in offspring exposed to PCNB levels as low as 169 mgkg-bwlday (LOAEL). Decreased body weight gain was also observed at the LOAEL in parents. The resulting NOAEL for this study was 1.2mglkg-bwlday (equivalent to a NOAEC of 24 mglkg-dietlday using standard FDA lab rat conversion);because of a lack of data to the contrary, PCNB degradates are presumed to have similartoxicityto that of theparent compound. Because PCNB has been demonstrated to contain residues of PCDDs and PCDFs, this assessment uses available data on the toxicity of these compounds to assess potential risks to birds and mammals. A great deal ofresearch has been conducted to characterize the toxicitiesof PCDDs and PCDFs especially relative to each other, since these compounds are o$en present together in the environment. The EPA (USEPA 2008b) and the World Health Organi$ation

### (Van Den Berg et al. 1998 and 2006) have established toxicity equivalency factors (TEFs) for dioxins and dioxin-like compounds (including PCDFs and polychlorinatedbiphenyls) as they relate to mammals and to birds. The TEFs of the PCDDs and PCDFs that represent contaminants of technical PCNB are provided in Table 3. These TEFs are used to estimatepotential risks to mammals and birds exposed to PCDDs and PCDFs present in technicalgrade PCNB. Table3. Toxicity equivalency factors (TEFs) for mammals and birds for dioxins and dioxin-likecontaminants of technicalPCNB 

### (USEPA2008b).



### I HxCDF 

### 1 0.1 

### 1 0.1 

### 1 I OCDF 

### I 0.0003 

### 1 0.0001 

### 1

'compared to 2,3,7,8-TCDD In the TEF approach,the toxicities ofthese chemicalsare related to 

### 2,3,7,8-tetrachlorodibenzo-pdioxin (TCDD). Chronic toxicity endpoints for mammals exposed to 2,3,7,8-TCDDhave been identified by the USEPA Office of Water (OW) for the Great Lakes Water Quality Initiative Criteria for the Protection of Wildlife (USEPA 1995). OW defined a NOAEL of 0.001 ygkgbwlday (1x10-~ mgkg-bwlday) for reproductive effects to mammals exposed to 2,3,7,8-TCDDin food. This NOAEL was based on reduced fertility in first (fi) and second generation (fi) rats exposed to a LOAEL of 0.01 pglkg-bwlday (Murray et al. 1979). OW also identified several studies reporting toxicity data involving chronic exposures of birds to 2,3,7,8-~~~~i however, these data were not considered in this assessment because, in all of the studies, the birds were dosed via intraperitoneal injection, not through their diet.

Page 12 of701.6. Risk Conclusions from OPP's previous PCNB Ecological Risk Assessment, supportingthe RED The following risk conclusions are fiom the environmental fate and ecological risk assessment written in supportofthe PCNB 

### RED in 2005(DPBarcode D291276). These conclusions are also summarized in Table 

### 4. The ecological risk conclusions discussed in the 

### RED did not consider risks from the contaminants associated with PCNB. Acute risk levels of concern (LOCs) were exceeded for freshwater aquatic animals. Chronic risk LOCs were exceeded for freshwater fish and invertebrates; chronic effects included reduced number of eggs produced and reductions in the number of young surviving. Based on acute-to-chronic ratios derived from freshwater studies, estimatedNQAECs for estuarinelmarine invertebrates suggested that chronic risk was possible fiom the uses of PCNB modeled in the assessment. No data were available to characterize the effects of PCNB on aquatic or terrestrial plants; therefore, it was not possible to assess the risks of PCNB to plants. Screening-level models indicated that exposure ofterrestrial animals to PCNB was likely through consumption of treated seed and foliar residues. However, the likelihood of acute mortality to birds and mammals was considered low given that PCNB is practically nontoxic to both birds and mammals on an acute exposure basis. Chronic LOCs were exceeded for birds and mammals following consumption of PCNBtreated seed and PCNB residues on forageitems (on treated fields). Although OPP does not typically estimate risks to terrestrial invertebrates, available data suggested that PCNB is practically nontoxic to adult bees. Table 4. Summary of risk conclusions from ecological risk assessmentfor PCNB supporting the 

### OPP RED (DP Barcode ~291276).


# I marine) Habitat
Aquatic (freshwater, estuarine and 

# I I Sediment -dwelling invertebrates Taxa
Fish, amphibians Water column invertebrates Plants 

# I Terrestrial 

# 1 I no 

# I Yes 

# I Exceeds Acute

Risk LOC'? Yes Yes unknown3 Exceeds Chronic RisKLOC~? Yes Yes unknown3

IAcute risk to listed species LOC exceeded ifrisk quotient (RQ)>0.05 for aquatic animals and >0.1 for terrestrial animals. 2Chronic risk LOC exceeded ifRQ>l.O. 3~nknown because no toxicity data are available with which to evaluate risk. 4Animals feeding on foliage, insects and seeds located on the treated field. Birds, amphibians, reptiles4 Plants

Page 13 of70 no unknown3 Yes unknown32. Accumulation ofPCNB and its Degradates in Aquatic Systems Based on available data, PCNB and its degradates, considered together, are considered likely to be persistentin the aquaticenvironment. Although theprimary route of degradationfor PCNB is through aqueous photolysis, the ideal conditions for this route of degradation (clear, shallow water) are limited under natural conditions as runoffwater tends to be turbid and incident light in surface water bodies is attenuated with increasing depth ofwater. EFED uses the Pesticide Root Zone Model coupled with the Exposure Analysis Model System (PRZMIEXAMS)to estimate pesticide concentrations in aquatic ecosystems. PRZM simulates pesticide application, movement and transformation on an agricultural field and the resultant pesticide loadings to a receiving water body via runoff, erosion and spray drift. EXAMS simulates the fate of the pesticide and resulting concentrations in the water body. The standard scenario used for ecological pesticide assessments assumes application to a 10-hectare agricultural field that drains into an adjacent 1-hectare water body, 2-meters deep (20,000 m3 volume) with no outlet. At the 2008 SAPmeeting, the EPA discussed the OPP's standardpond scenario and its use in the EXAMS for modeling surface and pore (benthic) water concentrations of persistent pesticides. The SAP expressed concernsover EXAMS' lack ofinclusion of sediment burial in its conceptual model, current model assumptions regarding pesticide dissociation from incoming sediments and model assumptions regarding pesticide mass transfer between the water column and benthic compartments of the standard pond. The following sections explorethese three concerns and the influences of model assumptions on estimated concentrations and associated risks of 

### PCNB and its degradates in aquatic systems. 2.1. Consideration of Pesticide Burial in Aquatic Exposure Modeling OPP's standard pond scenario used with EXAMS does not include burial of pesticide mass within the benthic compartment. It is assumed that although sediment burial of sorbed chemicals may occur in some natural water bodies, sediment deposits may be re-exposed in natural systems as a result of hydrodynamic processes and by bioturbation caused by animals in the benthic compartment. Therefore, pesticide loss from an aquatic system due to sediment burial is not conservative because temporarily buried pesticide mass is expected to be re-exposed in many natural systems. The SAP commented that burial of PBT chemicals in sediment deposits could represent a major removal mechanism and must be taken into account, either explicitly or implicitly in risk estimation for these types of pesticides. EXAMS can be used to model loss of pesticide mass from the benthic compartmentby using a first-orderrate constant (USEPA 2004b).
In the background document develop for the SAP (USEPA 2008a), EPA explored the( impact of the burial of pesticide-laden sediment on estimates of pesticide exposures in the water column and benthic area of a farm pond. EPA estimated a value for a first-order rate coefficient, based

Page 14 of70on the assumption that sediment burial is equal to the sediment residence timd. Sediment residence time in this case was estimated by dividing the average daily sediment inflow rate [mass per day] by the mass of the sediment in the benthic compartment. The daily sediment inflowrate was based on the Mississippi cotton modeling scenario because it represents a PRZM scenariowith a high soil erosion rate and a high burial rate. The resulting half-life due to burial was 222 days. This half-life is expected to represent a higher benthic sediment burial rate than would be derived using other PRZM scenarios.
To evaluate the impact of burial on PCNB estimates, OPP used the sediment residence time calculated above to estimate concentrations of PCNB and its degradates in water column and benthic zones ofthe OPP standard pond. Table 

### 5 and Table 6 provide the original peak, 21-d and 60-d EECs for PCNB in the water column and benthic compartments of the OPP standard pond as reported in the original Ecological Risk Assessment for PCNB (DP 291276), which used earlier versions of PRZM and EXAMS. These tables also include EECs calculated using the most current versions of PRZM (~3.12.2)~ EXAMS (v2.98.4.6) and the Pe shell (Pe5) with and without burial. In general, EECs generated for the original ecological risk assessment for PCNB are somewhat different compared to those generated using the most current versions of PRZM and EXAMS. This can be attributed to changes in the model versions (e.g., different method of applying curve number, incorporation of irrigation) as well as changes in the parameterization of the PRZM scenarios themselves (e.g., change in meteorological files, change in curve number, change in emergence date). Importantly, the impact of burial on concentrations estimated in the water column and the benthic layer (using the burial half-life, 222 d, in place of the benthic halflife of 2004) is relatively small,i.e., <lo%. Resulting RQs from EECsthat incorporate sediment burial areprovided in Table 7 

### - Table 9.None of the changes (revision of PRZM and EXAMS and consideration of burial) alter the risk conclusions of the previous ecological risk assessment for PCNB (DP 291276), i.e., that use of PCNB poses acute and chronic risk to freshwater fish and invertebrates, acute risk to estuarine/marine invertebrates, and chronicriskto estuarine/marine fish and invertebrates.

Page 15of 70Table

### 5. Surface water EECs for PCNB and its degradates. Values generatedwit33 and without consideration of burial. Use 

## I Pe4 shell* No burial ( Pe5 shell No burial 

## 1 Pe5 shellwith burial PeakEECs (pg/L)

*From Table 9 of original ecological risk assessmentfor PCNB. Turf Cabbage Peanuts Cotton Potatoes

Potatoes

Table 6. Benthic EECs for PCNB and its degradates. Values generated with and without consideration ofburial. 259 84 97 28 22

11

- - 

### 1 Cabbage 

### I 2 1 

### I 2 1 

### I 21- d EECs (pg/L)

60- d EECs (pg/L)

Use



### 1 Peanuts 

### 1 34 

### I 28 

### 1 27 

### 1 128 98 64 25 23
Turf Cabbage Peanuts Cotton 11

Turf Cabbage Peanuts Cotton Potatoes

Pe4 shell* No burial 

## I Pe5shell No burial 

## I Pe5 shell with burial



### I Cotton 

### I 12 

### I 14 

### I 13 

### I 128 98 64 25 23

11 187 5 6 46 20

139 36 25 14 5.1

Peak EECs(pg/L) Turf

Potatoes

Page 16 of 70110 55 3 7 16

79 35 22 10 5.7

Turf Cabbage Peanuts Cotton Potatoes 110 55 3

7 15

79 35 22 10 5.7

108

4.2 21- d EECS(pg/L)

*From Table 9 of original ecological risk assessment for PCNB. 101 20 3 0 12 3.6 57

4.7
Turf Cabbage Peanuts Cotton Potatoes 55

4.5

53 20 26 13 4.2 106 21 33 12 4.1
5 1 18 25 12 4.0 56 2 1 28 13 4.6 54 19 27 13 4.4**From Table 9 of originalecologicalrisk assessment for PCNB. Table 7. Acute RQs forfreshwater fish and invertebrates based on peak EECs generated with and without consideration of sediment burial.

Table 

### 8. Acute RQs for estuarinelmarine fish and invertebrates based on peak EECs Use
Turf Cabbage Peanuts Cotton Potatoes

generated with and without consideration of sediment burial.

*RQ exceeds acute listed-species LOC (0.05)



## 1 No burial 

## 1 No burial 

## 1 wl burial 

## 1 No burial 

## I No burial 

## 1 wl burial 

# -

I Turf I 0.03 I 0.02 1 0.02 1 21.6" 1 10.7" 1 10.7" 1 Pe5 shell wlburial

1.28" 0.98" 0.64' 0.25" 0.23" Fish (LCs0= 100 pgL) (Invertebrates (ECS0 =$70 vg/L)

Use

I I I I Cabbane 0.01 0.01 0.01 7.00" 

### 1 8-17" 

### 1 8.17" 

## 1 Pe4 shell*" No burial

2.59" 0.84" 0.97" 0.28" 0.22" Pe4 shell** No burial

0.34" 0.11" 0.13" 0.04 0.03

Fish (LCs0=7900pglL) Pe4 shell** 

# I Pe5 shell 

### ( Pe5 shell Pe5 shell No burial 1.28" 0.98" 0.64" 0.25" 0.23"



### I Potatoes 

### 1 <0.01 

### 1 c0.01 

### 1 c0.01 

### 1 1.83" 

### 1 1.92" 

### 1 1.92" 

### 1 Pe5 shell 

### ' No burial
,

0.17" 0.13" 0.08" 0.03 0.03

Peanuts

I I

*RQ exceeds acute listed-species LOC (0.05) **From Table 9 of original ecological risk assessment for PCNB. Pe5 shell wlburial

0.17" 0.13" 0.08" 0.03 0.03

0.01

2~~s generated using 2 1 -d surface water EECs £komTable 5. *RQ exceeds chronic LOC (1.O) **From Table 9 of original ecological risk assessment for PCNB. Cotton

Table 9. ChronicRQs for freshwater fish and invertebrates based on EECs generated with and without consideration of sediment burial.

2.2. Equilibrium between Sediment and Water Column Concentrations 0.01

Use
Turf Cabbage Peanuts Cotton Potatoes

EXAMS takes into consideration the sorption and desorption of sediment-bound pesticide that enters the pond from the PRZM field. In EXAMS, desorption ofpesticide mass is acqounted for on the simulationday of the runoff event that brings the sediment-bound pesticide mass into the pond. This is accomplished using the parameter called PRBEN, which distributes a fraction of the sediment-bound pesticide directly to the benthic compartment of the pond. The remaining <0.01

Page 17of70 0.0 1

'RQS generated using 60-d surface water EECs from Table 5. 8.08* 

### ( 5.33" 

## 1 5.33" <0.01

Fish (NOAEC = 13pg/L)' Pe4 shell** No burial 10.7" 2.8" 1.9" 1.1" 0.4 Invertebrates (NOAEC = 18pg/L) <0.01

Pe4 shell** No burial 10.4" 3.1" 2.6" 1.1" 0.6 2.33" 

### 1 2.08" 

### 1 2.08"

Pe5 shell No burial 6.1" 2.7" 1.7" 0.8 0.4 Pe5 shell W/burial 6.1" 2.7" 1.7" 0.8 0.4 Pe5 shell No burial 6.1" 3.1" 2.1" 0.9 0.6 Pe5 shell w/ burial 6.1" 3.1" 2.1" 0.8 0.6fraction of the sediment-bound pesticide mass remains in the water column of $e pond to equilibrate. In the OPP standard pond, PRBEN is set to 0.5, "based on the observation that, in general, about 50% of sorbed chemical is usually labile and about 50% recalcitrant to rapid reequilibration in water" (USEPA 2004b). The organic carbon partition coefficient (Koc) of a chemical can be used to explore reasonable proportions of pesticide mass that would be expected to desorb from sediment to reach equilibrium within the water column (USEPA 2008a). The fraction of pesticide expected to be sorbed to 30 mg/L of suspended sediments in the water column (this is the assumed concentration of suspended sediments in the standard pond) will vary based on a compound's Koc. Using a Koc of 6470 Llkg-oc to represent of PCNB and its degradates, the fraction on solid would be less than 0.1 (see Figure 4.11 of USEPA 2008a). This indicates that an appropriate PRBEN value for PCNB and its degradates would be less than the default value of 0.5. Use of a PRBEN value <0.5 would result in an increase in peak EECs in the water column. Since the EECs from the standard pond (without alteration of PRBEN) are already sufficient to result in RQs that exceed acute risk LOCs for aquatic animals, use of a different PRBEN value would not change the conclusion that PCNB and its degradates pose risks to aquatic animals residing in the water column. 2.3. Mass Transfer of Pesticide from Water into Sediment
In EXAMS, the mass transfer coefficient (MTC) controls the rate of pesticide movement from the water column compartment into the sediment compartment of the OPP standard pond. The pesticide concentration in the water column should increase as MTC values decrease. Conversely, the sediment pore water and sediment concentrations should decrease as MTC values decrease. A sensitivity analysis was conducted to assess the impact of changes in the value of MTC on concentrationsof PCNB and its degradates in the water column and sediment pore water. This sensitivity analysis was performed using MTC values ranging 3.0x10-~ to 3.0x10-~ m2/hr; the default value of the MTC in the OPP standard pond is 3x10-~ m2/hr. Results were generated using the most current versions of PRZM/EXAMS and the pe5 shell. Results indicate that the peak water column concentration is not particularly sensitiveto orders of magnitude changes in the value ofthe MTC (Table 10). Table 

### 10. Concentrations ofPCNB and its degradatesin the water column and pore water of the OPP standard pond with different mass transfercoefficient values. Results are based on PCNB use on turf.
MTC Value (m2/hr)
3x10~ 3x10-~ 

### * 3x10-~ 3x1 

### o-~ 3x10-' *Default value
Page 18of70 BenthicEECs (porewater?pg/L) Water Column EECs (@L) 60-d 68 53 l9

- 

### , 8.8

5.3 Peak

80 57 19 8.9 5.3 60-d

68 79 98 101 102 21-d 79 56 19 8.8 5.3 Peak

118 128 129 129 129 21-d 86 110 119 

## 1 120 120Acute RQs based on these concentrations are provided in Table 11.Regardless of the value of the MTC, acute RQs for freshwater fish and estuarinelmarine invertebrates exceed LOCs for acute risk to non-listed and listed species. Also, RQs for freshwater invertebrates exceed the acute risk to listed species LOC for all values of MTC. Therefore, changes in the value of the MTC do not alter the risk conclusions of the previous ecological risk assessment for PCNB (DP 291276), i.e.,that use of PCNB poses acute risk to freshwater fish and invertebrates, as well as estuarinelmarine invertebrates. Table 11. Acute RQs generatedfor different

### MTCvalues. RQs generated usingPeak water column EECs from Table 10 

### (udL).

v r

When the MTC value increases, chronic EECs and associated RQs for fi-eshwater fish and invertebrates increase. When the MTC is decreased by an order of magnitude below the default value (from 3x1

## oq5 t03x10-~ 

### m2/hr), chronic water column EECs decrease by 22% for the 21-d EEC and 14% for the 60-d EEC (Table 10). Despite this decrease in exposure, RQs for freshwater fish and invertebrates exceed the chronic risk LOC of 1.0 (Table 12). Therefore, use of a differentMTC value would not change the conclusion that chronic exposures to PCNB and its degradates pose a risk to aquaticanimalsresiding in the water column. MTC value

3x10"

Table 12. ChronicRQs generatedfor differentMTC values. RQs generatedusing,water Freshwater fish (LCs0

= 100 pg/L)



# I *Default value 1 RQ exceeds acute risk to non-listed speciesLOC (0.5) 2RQ exceeds acute risk to listed species LOC (0.05) 1.29"'

columnEECs from Table 11 

### (&I,).

Page 19of70 Freshwater invertebrate (ECso=770 pg/L)

0.17'

MTC value

3x10'~ 3x10-* Estuarinelmarine invertebrate (ECSo = 12 pg/L)

10.7S1>'

Freshwaterfish

*Default value 'RQS generated using 60-d surface water EECs. 2~~s generated using 21 -d surface water EECs. 3RQ exceeds chronic risk LOC (1.0) 7.g3 7.g3 Freshwater invertebrate

6.73 6.73 

### C)-

### 3. Bioaccumulation of PCNB and its Degradates and Contaminantsin Aquatic Oirganisms and Associated Ecological Risks The environmental fate and ecological risk assessment written in support of the Raregistration Eligibility Decision (RED) for PCNB provided evidence that PCNB and its degradates have potential to bioaccumulate in aquatic ecosystems and would therefore have the potential to pose risk to mammals and birds that consume aquatic animals.At the time the assessmentwas written, no tool was available to quantifl the risks to mammals and birds consuming aquaticaimalsthat have accumulated pesticide residues. Since the ecological risk assessment chapter was finalized, the 

### KO, (Based) Aquatic Bioaccumulation Model (KABAM; version 1.0; USEPA 2009) was developed and has been implemented for risk assessment by OPP. KABAM estimates bioaccumulation of pesticides in aquatic ecosystems and subsequent exposure and risk to mammals and birds consuming aquatic organismscontaminated with the pesticide. Figure 2 depicts the foodweb of KABAM. At the October 2008 meeting with the FIFRA SAP, the OPP presented an approach of using multiple methods for assessing aquatic bioaccumulation 

### (i.e., lab studies, field studies, mathematical models). The SAP suggested that such an approach should be based on modeling and rely upon lab or field data to verify model assumptions and/or make adjustments to model parameters. The SAP generally supported the use of food web bioaccumulation models for assessingbioaccumulation. This assessment follows the suggestion of the SAP to rely upon model estimates of bioaccurnulation and to supplement model estimates using available empirical data. This assessment use's KABAM to build upon previous conclusions that PCNB and its degradates may bioaccumulate in aquatic systems. Risks of PCNB and its degradates to mammals and birds that consume aquatic organisms are also assessed using KABAM. Available information from laboratory bioconcentration studies are used to validate estimated biocorrcentration. Bioaccumulation estimates of contaminants of technical PCNB are also assessed, along with their associated risks.

Page 20 of70Water column

Medium fish

Filter feeders Benthic invertebrates



## I Sediment 

## I Figure 2. Conceptual model depicting movement (see arrows) of PCNB and its degradates from sediment and water to various trophic levels in an aquaticfood chain (e.g., phytoplankton, zooplankton, fish) and to birds and mammals consuming aquatic organisms. Organisms also take up PCNB and its degradates from the water column.

3.1. Bioconcentration Factors (BCFs) ofPCNB and itsDegradates 3.1.1. Estimated BCFs Using Modeling KABAM was run to estimate BCFs for aquatic organisms accumulating PCNB and its degradates. The model used a logarithmic transformation of the octanol water partition coefficient (Log KO,) of 5.0 to represent the partitioning of PCNB and its degradates to aquatic organisms. The SAP recommended that KO, data are carefully reviewed before their use in bioaccumulation models and that a "best value" (notjust an average value) be selected for use in modeling. They recommended that selection of the "best value" should consider uncefiainties in different measurement methods and chemical properties. Appendix A of this documelptprovides a characterizationof available

### K,, data for PCNB and its degradates and describes haw the Log 

### L, value of 5.0 was selected to represent PCNB and its degradates.

Page 21 of 70In estimatingBCFs, it is assumedthat the concentrationof dissolved oxygen in water is 

### 5 mg/L and the water temperatureis 15OC.Thebody characteristics of aquatic organisms in various trophic levels are consistent withthe defaultvalues of KABAM ( Table 13). The resulting bioconcentration factors (BCFs) for the various aquatic trophic levels are depicted in Table 14. Estimated BCFs indicate that PCNB and its degradates are expected to bioconcentrate in aquatic organisms.

Table 13. Characteristics ofmodel aquatic organismsused to derive BCFs for PCNB and its degradates. Values are KABAM default assumptionsfor aquatic organismsin model ecosvstem. d Trophic Level phytoplankton
benthic invertebrates filter feeders Wet Weight (kg) N/A

small fish medium fish

Table 14. KABAM-estimatedPCNB residueBCF values for aquatic organismsbised on total wei~ht. 1.OE-04



### [ large fish Lipid content 2.0% zooplankton

1.OE-02 1.OE-01 12.0% 3.0%

1.OE+00

. -

.. . - . . - - ---- Non-lipid organic matter content
85.0% 8.0% 1.OE-07

4.0% 4.0%

Trophic Level Phytoplankton


### 1 Filter Feeders 

### 1 2401 

### 1 Water content 90.0% 3.O% 2 1.O% 1.OE-03

4.0%

BCF (ygtkg-NTV)/( yg/L) 4801

I 76.0% 13.0% 2.0% 23.0% 23.0%

Benthic Invertebrates

3.1.2. Empirical BCFs 85.0% 73.0% 73.O% 23.0%

Zoo~lankton 36.53

Small Fish Medium Fish

Large Fish

Registrants have submitted studies on bioconcentration involving bluegill sunfish (Lepomis macrochirus) exposed to PCNB (Guideline 850.1730). In addition, EFED used ECOTOX, a database ofpublically available scientific literaturemaintained by EPA's Office of Research and Development, to identify studies which are related to bioconcentration of PCNB in algae and in fish. These studies are described below, with reviews ofthe studiesprovided in Appendix B of this document. Reported BCFs of the laboratory studies along with values estimated using KABAM are available in Table 15. Modeled estimates ofBCF were derived using KABAM and input values representing the study conditions (i.e., water temperature, fish body weights, dissolved oxygen, pesticide concentration in water). In cases where information was not provided in a study report to define relevant study conditions, default parameter vzllues were used. BCFs in Table 15 are different than values reported in Table 14, which are parameterized to represent the standard farmpond used by OPP for ecological risk assessments. 73.0%

3421

4699 4699 4806

Page 22 of 703.1.2.1. Registrant-Submitted Studies
In a registrant-submitted bioconcentration study (MRIDs 4 1200001 and 4 1951701 ), PCNB residues accumulated in bluegill sunfishexposed to 14c-pc~~, at a mean aqueous concentration of 0.88 pg/L (range of 0.47-1.2 pg/L) for 35 days. In this study, PCNB represented a small fraction (22% on average)ofthe totalradioactive residues present in the treatment water, leading to uncertainty in the specific residues that the fish were exposed to during the study. The maximum BCF of the study, which was observed at day 35, was 1100for total residues in whole fishtissues. The KABAM-predicted BCF (4806; Table 15)was 4.4X higher than the maximum BCF observed in this study. In this study, it appeared that PCNB residues in fish reached a plateau at day 28 (residuesmeasured at days 28 and 35 were similar), indicatingthat steady state was likely reached in test organisms by day 28 of the study. Radioactive residues in fish tissues were predominantly composed of PCTA, indicating that PCNB was metabolized by fish to one of the PCNB's degradates of concern. At the end of the study's 21-day depuration period, 78- 82% of the accumulated 14c residues were eliminated from the fish tissues, which corresponded to atotal depuration rate constant of 0.0732 d". KABAM was used to estimate a total depuration constant of 0.125 d-I,which represents chemical loss through respiration, fecal elimination, and growth dilution, assuming that the loss through metabolism is 0. The similarity between the empirical and estimated total elimination rate constant supports the assumption that loss pathways of PCNB and its degradates can be represented by respiration, fecal elimination and growth dilution and that metabolism does not contribute significantlyto the elimination ofPCNB and its degradatesfrom fish.
In a second registrant-submitted bioconcentration study (MRIDs 40580202 and 43179301), PCNB residues accumulated in bluegill sunfish exposed to radiolabeled PCNB, at a mean aqueous concentrationof 0.54 pg/L (range of 0.31-0.67 pg/L) for 28 days. The maximum BCF of the study, which was observed at Day 28, was 960X. The KABAM-predicted BCF (4806; Table 15) was 5.OX higher than the BCF observed in this study. At the end of the exposure period of the study, BCFs had not yet reached a plateau, suggesting that steady state was not reached in test organisms; however, given the results of the previously described registrantsubmitted study, it is likely that this study was close to reaching steady state. As with the previously described registrant-submitted study, PCNB residues in fish tissues were predominantly (in this case, >90% of residues in edible tissues) composed of PCTA. At the end of the 2 1 -day depurationperiod, 8 1-84% of the accumulated I4c residues were eliminated from the fish tissues, which corresponded to a total depuration rate constant of 0.0836 d". This depuration rate constant is similar to the one calculated for PCNB and its degradates (0.123 dm') using KABAM. This indicatesthat the KABAM estimation of depuration, without consideration ofmetabolism, is similarto what has been observed in the laboratory. 3.1.2.2. Studiesfrom the Public Literature (identified using 

### ECOTOX) Several articleshave reported the results of a bioconcentration study with green algae (Chlorella fusca) exposed to 50 pg/L radiolabeled PCNB (Geyer et al. 1984; Freitag et al. 1982 and 1984). After a 24-hour exposureperiod, 

## I4c residues in algae and in water were measured, with 67% of total mass in algae and 38% in water. The resulting BCF was 3100, which is within a factor of

Page 23 of 701.5X of the KABAM-predicted BCF (4801



### . Potential degradatiodmetabolism of PCNB is not 

# h discussed in the articles; however, since 

# ' C residues were measured, it was assumed that the reported BCFs are representative oftotal PCNB and its degradates. An additional study involving 

### C,fusca reported by Korte (1978; one of the authors of Freitag et al. 1982 and 1984) included two BCFs resulting from I-d exposures of green algae to 49 pg/L 14c-labeledPCNB. Values were reported on a dry weight basis as 14,000 and 22,000 (units: (pglkg-dw)/(pg/L)).Assuming that this species of green algae contains 1 g dry weight for every 5 g wet weight (based on Geyer et al. 1984), these dry weight BCFs can be translated to wet weight BCF values of 2800 and 4400 (units: (&kg-ww)/(pg/L)), respectively. The BCF value estimated by KABAM for PCNB and its degradates in phytoplankton (4801) is within a factor of 1.1-1.7 of the reported values (Table 15). Potential degradation/metabolism of PCNB is not discussed in the article; however, since 

## 14c residues were measured, it was assumed that the reported BCFs are representative of total PCNB and its degradates.
In a bioconcentration study with golden orfes (Leuciscusidus melanotus), five fish were exposed to 0.4 pg/L 14c-labeledPCNB for 3 days. The reported BCF was 1140 (Freitag et al. 1982 and 1984). In a second study with golden orfes, conducted under similar conditions, the BCF was 1130 (Korte 1978). The KABAM-estimated BCF value for total PCNB and its degradates in fish (4806) is within a factor of 4.3X of the reported values for golden orfes (Table 15). Given that these studies were only conducted for 3 days, and given the observation of the studies with bluegill sunfish (MRIDs 41200001 and 4195 1701) that steady state was reached for bluegill sunfish in approximately 28 days, it is uncertain whether steady state was reached in the golden orfes. If steady state was not reached, the reported BCFs could underestiaate values representative of steady state conditions.Potential degradation of PCNB is not discussed in the articles; however, since 14c residues were measured, it was assumed that the reported BCFs are representative ofPCNB and its degradates.
In a bioconcentration study with rainbow trout (Oncorhynchus mykiss, formerly Salmo gairdneri), fish were exposed to 0.69 pg/L PCNB in a mixture that contained 17 other chloronitrobenzenes for 36 days. The BCF values for PCNB measured at 5, 12, 20, 28, and 36 days ranged fiom 114 to 261, with an overall mean of 17 1 (standard deviationk89). The authors ofthis studyreported that fish tissue concentrations ofPCNB reached equilibrium within 

### 5 days, but significant differences in BCFs were observed at different time periods (Niimi et al. 1989). The BCF value estimated by KABAM for PCNB and its degradates in fish (4806; Table 15) is within a factor of 6.3-14X ofthe reported values for rainbowtrout. PCNB was not radiolabelled, but was quantified using gas chromatography. PCNB's degradates were not included as analytes, indicating that reported BCFs likely underestimate values representative of PCNB and its degradates. Additionally, there is considerable uncertainty regarding how other chloronitrobenzenes present in the study may have affected uptake and/or depuration of PCNB and its degradates.
In another bioconcentration study with rainbow trout (Oliver andNiimi 1985),fish were exposed for different time intervals (7, 21, 35, 75 and 96 days) to a mixture of 18 chlorinated and brominated organic chemicals, including PCNB. Fish were exposed at either 0.0014 or 0.014 pg/L PCNB. BCFs measured at the indicated time intervals ranged from 90 to 950 for PCNB.

Page 24 of 70The KABAM estimated BCFs for total PCNB residues in fish were 8006 for the 0.0014 pg/L concentration and 7506 for the 0.014 pg/L concentration (Table 15; differences in BCF values can be attributed to different fish body weights and lipid contents). KABAM-estimated values deviated by factors of 8.4X to as much as 83X from the values reported in this study. As in the previously discussed study (Niimi et al. 1989), only PCNB parent was measured in this study, likely resulting in an underestimation of the BCF that would be representative of PCNB and its degradates. Several articles reported the results of a BCF study with wild-caught topmouth gudgeon (Pseudorasbora parva) (Kanazawa 1980; 1981a; 1981 b; 1983). In this study, 15-20 fish were exposed to 10-20 pg/L PCNB for 14 days, with a resulting BCF of 238 for PCNB. The KABAM-estimated BCF for PCNB and its degradates in fish (4565) is within a factor of 19Xof the reported value for topmouth gudgeon. As with the studies with rainbow trout, only PCNB was measured in this study, likely resulting in an underestimation of the BCF that would be representative ofPCNB and its degradates.

3.1.2.3. Summary of comparison between empirical and estimated BCFs In cases where laboratory BCF studies included PCNB and its degradates, there is generally good agreement between empirical and estimated BCFs, where estimated values are within a factor of 1.1to 5X of observed values. Differences between empirical and estimated BCFs may be attributed to several factors, including: 1) A lack of steady-state in test organisms of laboratory studies, resulting in underestimated BCF values. 2) A differencebetween the actual lipid content oftest fish (which is generally not provided in BCF studyreports) and the lipid content ofthe fish assumed for KABAM (4%). 3) Inconsistency between the assigned Log 

### &, value of PCNB and its degradate~ (5.0) and the actual partitioning of PCNB and its degradates in aquatic organisms, As noted in Appendix A, reported Log 

### KO, values ofPCNB range of 4.22-5.30 and estimated Log 

## L, values ofPCNBYs degradates are abroader range of 3.7-5.8. 4) Several studies available in the scientific literature analyzed fish tissues for only PCNB. Thus the results likely underestimate BCFs associated with PCNB and its degradates. This is supported by observations associated with the two registrant-submitted BCF studies where the PCTA was identified asrepresenting the majority ofPCNB residues in fish.

Page 25 of70Table 15. Summary of reported and estimated (using KABAM) BCFs from studies submittedby registrants and availablein

Page 26 of 70 the scientific literature.

Korte 1978 Freitaget al. 1982and 1984

Kanazawa 1980; 198la; 1981b; 1983 Niimi et al. 1989 Oliver and Niimi 1985 Oliver and Niimi 1985 NA = not applicable 1 Estimatedusing KARAM- Input parameters were as follows. Log KO, = 5.0 and study parameter values for weight, 11p1dcontent, dissolved 02, temperature and PCNB concentration in water. All other parameters were set to KABAM defaults.In cases where data were not prov~ded in the studyreport (e.g,lipid content), KABAM defaultvalues were used 2 The studyreport did not provide information on the lipid content ofthe test organisms.Therefore, the KABAM defaultwas used in estirnattngBCF and the total elimination rate constant. 3 The study report did not prov~de informationon the dissolved oxygen concentration.Therefore, it was assumed that the test solutlonwas at saturation. 4 Calculated as.Est~mated +Emp~r~cal Golden

orfe Golden

orfe Topmouth gudgeon Rainbow

trout Rainbow

trout Rainbow

trout 3
3

3 0

5-36
7-96
7-96 3.5 1.5

3.5

178
237
245 42
42

42

0.84
7.2
6.7 83

83

83
83
83 23
22.5

20

15
15
15 0.4
0.4

10-20

0.69
0.0014
0.014 I 1130
1140

23 8

1 14-26 1
380-950
90-4 10 I 4806
4806

4806

1646
8006
7506 4.3
4.2

20

6.3-14
8.4-21
18-83 Yes
Yes

No

NO
No
No3.2. Metabolism ofPCNB in Aquatic Organisms The SAP recommended that when data are not available from which to estimate chemical metabolism by biota, a rate of zero could be assumed. However, they cautioned that this can produce highly conservative estimates and suggested that EPA employ a recent approach by John Arnot for estimatingmetabolism as a step forward.
In using KABAM with its default settings, it is assumed that the elimination of a pesticide from aquatic organisms through metabolism does not occur, i.e., the metabolism rate constant 

### (kM) equals 0. In the case of PCNB, there is evidence from registrant-submitted BCF studies with bluegill sunfish that PCNB is metabolized by fish; however, PCNB is metabolized to PCTA, which has similar bioaccumulative properties (based on KO,) as the parent compound. When KABAM is used to predict BCFs for comparisonto empirical values (Table 

### 151,estimated values were within a factor of 1.1 to 

### 5 of empirical BCFs that were based on PCNB and its degradates. When empirical BCFs were based on PCNB parent compound alone, KABAM predictions were much higher than the empirical values for PCNB alone (by factorsrahging from 6.3X to 83X). This indicates that KABAM predictions of bioconcentration are consistent with empirical studiesinvolving totalresidues ofPCNB. Depuration rate constants for PCNB and its degradates fkom registrant-submitted BlCF studies with bluegill sunfish were within a factor of 2 of predicted total depuration rate constants for PCNB and its degradates. This indicates that additional depuration caused by metabolism was not a significantprocess. Therefore, in this assessment, it is assumed that metabolism does not increasedepuration ofPCNB and its degradates. 3.3. PCNB Residues in Fish Tissues 3.3.1. MonitoringData OPP has identified two monitoring studiesthat include data for PCNB concentrations in fish. In the first study, USEPA collected fish samples at 362 sites. PCNB was detected in 

### 4 samples of fish, with all detections40 &kg (USEPA 1992).
In the second study, data on PCNB concentrations in fish are available from the National Lake Fish Tissue Study (NLFTS), which was the first survey of fish contamination in lakes and reservoirs in the 48 contiguous states based on a probability survay design (http://www.epa.aov/waterscience/fish/studv/, Stahl et 

### al. 2009, and Olsen et al. 2009). This study included 268 of the chemicals with PBT properties, including PCNB. The USEPA implemented the study in cooperation with states,tribal nations, and other federal age~cies, with field collection occurring at 500 lakes and reservoirs over a four-year period (2000-2003). The sampled lakes and reservoirswere selected using a spatially balanced unequal probability survey design from 270,761 lake objects in USEPAys River Reach File Version 3 (RF3). In tqe NLFTS, there were a total of 1003 composite fish samples in the U.S. that were evaluated for these samples, 90 (9%) contained detectable levels of PCNB, with a concentratio

Page 27 of700.766-5.54 pg/kg. PCNB was detected in fish samples collected throughout the 4-yew sampling period and throughout the continental US (including locations in: AL, 

### AZ, CA, CO,FL, IL, 

### IN, KS, ME, MI, MN, MS, MI, MT, NE, NV, 

### NH, NJ, NY, OH, OK, OR, RI, TX, UT, VA, WAY WI, WY). Detections occurred inboth predator and bottom-dwelling fish. These monitoring data likely underestimate PCNB's residues of concern because the monitoring studies focused only on PCNB; fish tissues were not analyzed for PCNBYs degradates. This is especially a concern given that the PCNB degradate PCTA has been identified as representing the majority ofPCNB residues in the two registrant-submitted BCF studies with bluegill sunfish. Additionally, these monitoring data likely underestimate concentrations of PCNB since the fish sampled during this monitoring program were not targeted to coincide with either PCNB application areas (spatially)or application periods (temporally). As such, the residues measured in the fish samples likely underestimate residues in fish collected in close proximity to PCNB use sites. 3.3.2. Estimated Concentrations ofPCNB and its Degradates in Tissues of Aquatic Organisms The bioaccumulation of PCNB and its degradates in a freshwater aquatic ecosystem was estimated using KABAM in default mode (see user's guide for full description), with a Log 

### KO,

= 5.0 (see Appendix A) and a 

### &, = 6470 L/kg-oc (DP Barcode D291276). Surface water column and benthic compartment (pore water) estimated environmental concentrations (EECs) were determined for PCNB use on turf, cabbage, peanuts, cotton and potatoes. Since KABAM assumesthat aquatic organisms at steady state, it is necessary to enter surface water and benthic EECs that are representativeof a steady state concentration of the chemical being modeled. The estimated time to steady state for PCNB (based on the Log 

### Ed, of 5.0) is 30 days. This is supported by the observation that steady state was likely achieved within 28 days during a laboratory BCF studies with fish (MRIDs 

### 4 1200001 and 4195 1701).Therefore, the 1 -in-10 year EEC averaging period used to represent the concentration of the pesticide in the sediment pore and surface waters of the aquatic habitat was selected as 21 days, which is the closest averaging period used by the PRZM/EXAMSto calculate aquaticEECs. For these different uses, sediment pore water, 21-d EECs were between 4.6 and 56 yg/L and surface water, 21-d EECs ranged between 11and 110 pg/L (Table 16). Table 16.21-daypore water and surface water EECs (pg/L;21-d values) ofPCNB and its degradates generated by currentversion of

### PRZMIEXAMS. Use 

## 1 Surface Water (pg/L) ) Sediment Pore Water (pg/L)



### I potatoes 

### 1 11 

### I 4.6 

### I

Turf Cabbage Peanuts Cnttnn

Estimated concentrations of PCNB and its degradates in tissues of aquatic orgqnisms are provided in Table 17.Predicted concentrations of PCNB and its degradates in aquaticlorganisms range 28 to 1020 mgkg (wet weight), with values differing between trophic levels and for

Page 28 of70 110 55 37 16 56 2 1 28 13different PCNB uses. Concentrations ofPCNB and its degradates intissues of aquatic organisms (Table 17) are used to derive RQs based on dose-based and dietary-based exposures of mammals, birds, terrestrial-phaseamphibians and reptiles consuming contaminated aquatic prey. Table 17.Estimated concentrations (mgkg-ww) ofPCNB and its degradatesin aquatic organism at different trophiclevels based on different uses of

### PCNB. Values calculated using KABAM and 21-d EECs from 

### PRZMIEXAMS.


### I Phytoplankton 

### 1 500 

### 1 250 

### 1 168 

### 1 73 

### 1 50 

### 1 

# - Trophic Level

According to the user's guide for 

### KABAM, 

### KO, is the input parameter that has the most influence on the predictions associated with bioaccumulation. As noted previously, a Log 

### KO, of 5.0 was used to represent PCNB and its degradates. A weight of evidence approach was used to determine the appropriate Log 

### KO, to represent PCNB and its degradates (Appendix A); however, there is some uncertainty associated with the selected Log 

### K,,, value. The first source of uncertainty is related to the available Log 

### KO, values for PCNB, which range fiom 4.22 to 5.30. Considerationof the range of Log 

### KO, values available for PCNB indicates that predicted concentrations of PCNB and its degradates in aquatic organisms can vary by an order of magnitude (Table 

### 18 and Table 19),with tissue concentrations increasing with 

### KO,. The second source of uncertainty is associated with the assigned Log 

### KO, value (5.0) used to represent PCNB and its degradates is the differences in partitioning of PCNB's degradates to each other and to PCNB. The major degradates of PCNB are PCA, PCTA and PCB; estimated Log 

### KO, values are 4.30, 5.2 and 5.8, respectively (estimated using EPISuite v.4.0 (USEPA 2008~)). Although the estimated Log 

### &, value for PCA is lower than 5.0, suggesting that predicted concentrations of PCNB and its degradates would be lower than predicted (Table 18 and Table 

### 19), the predicted value for PCA still falls within the range of empirical values available for PCNB. As described above, available BCF studies with fish indicate that PCNB is metabolized by fish to PCTA. Giventhat PCTA has a higher estimated Log 

### KO, value than 5.0, it is possible that PCTA will depurate to a lesser extent than PCNB, once PCTA is formed. Therefore, PCNB and its degradatesmay be more likely to accumulate in aquatic organisms than predicted by the methodsused in this assessment.

Zooplankton Benthic Invertebrates Filter Feeders Small Fish Medium Fish Large Fish

Page 29 of70 Turf (mglkg-ww)
3 86 425 279 627 740 1020 Cabbage (mg/kg-ww)
193 211 139 3 12 368 510 Peanuts (mglkg-ww)
130 145 95 213 252 346 Cotton (mglkg-ww) Potatoes (mglkg-ww)
56 63 4 1 92 109 150 3 9 42 28 62 74 102Table 18.Predicted concentrations ofPCNB and its degradatesin aquatic organismsusing different 

### Log 

### &, values to represent PCNB and its degradates. Values arebased on PCNB

"Values are used to generateRQs (Table 35

### - Table41). Phytoplankton Zooplankton Benthic Invertebrates Filter Feeders

Small Fish Medium Fish

Large Fish

A major assumption associated with KABAM is that the model assumes that the chemical has reached steady state within aquatic organisms. Given the episodic nature of pesticide applications, sporadicpeak exposuresto aquatic organisms would be expected. The EEC used to represent the concentration of thepesticide in the pore and surfacewaters of the aquatic habitat is selected so that the averaging period (i.e., 4-d, 21-d, 60-d, 90-d, 1 year), is consistent with the time to steady state estimated for that chemical. Generally, the time to reach steady state can be related to the Log 

### KO, of a chemical, with increasing time required as the Log 

### &, increases. 

### In the case of PCNB and its degradates, the estimated time to steady state is 30 days. This time to steady state is supported by a registrant-submitted BCF study with bluegill sunfish (MRIDs 41200001 and 41951701) where steady state was reached at approximately 28 days! Since the standard output file fiom PRZMIEXAMS does not include a 30-d average, the nCxt closest averaging period was selected (i.e., 21 days). The use of the 21-d average (1-in-10 yew) EEC to represent concentrations of PCNB and its degradates potentially results in overestimbtes of the steady state concentrationsof PCNB and its degradates in tissues of aquatic organism



### . In order to account for uncertainty associated with the use of the 21-d average EEC to re resent the steady state concentration of PCNB residues in water, KABAM was run using

# 4 0-d EECs generated using the current versions of PRZWEXAMS (Table 20). The resulting eqtimates of 85 63 67 44 89 9 1 99

Table 19.Predicted concentrations ofPCNB and its degradatesin aquatic organisms using different Log Kow values to represent PCNB and its degradates. Values arebased on PCNB use on potatoes (low end ofEECs) and calculated usingKABAM.

Page 30 of70 Trophic Level Phytoplankton Zooplankton Benthic Invertebrates Filter Feeders Small Fish Medium Fish Large Fish 500 386 425 279 627 740 1020 972 788 891 585 1467 1969 3455

*Valuesare used to generateRQs (Table 35

### - Table4 1). LogKm 4.22 (mg/kg-ww) 9 6 7 4 9 9 10 5.0" (mglkg-ww) 50 3 9 42 28 62 74 102 5.30 (mglkg-ww) 97 79 89 58 146 196 344PCNB and its degradatesin aquatic organismswere lower (Table 21), but still onthe same order ofmagnitude compared with tissue concentrations generated from the 2 1 -d EECs (Table 17). Table 20.60-day average sedimentpore water and water column ofPCNB and its degradates (generated by PRZMIEXAMS). Use Turf Cabbage Peanuts Cotton Potatoes

The ecologicalrisk assessment chapter developed in 2005 by OPP supporting the reregistration decision (DP Barcode D291276) described the potential for PCNB and its degradates to volatilize. The version of the PRZMIEXAMS model used to generate EECs for this lassessment is unable to account for volatilization; however, volatilization could be a significapt route of dissipationPCNB and its degradates when PCNB is not incorporated into the soil at the time of application. A provisional version of PRZMIEXAMS (PRZM9; dated November 10, 2004) which accounts for volatilization was used to evaluate the impact of this process oq estimated exposure. Results indicated that 21-day and 60-day EECs decrease due to volatilization by approximately 22% and 28%, respectively, for the turf use. If the 21-d EECs in both the surface water and sediment compartments (Table 16) are decreased by 22%, estimated conce~trations of PCNB and its degradates in aquatic organisms are lower (Table 22), but still approximatelythe same order ofmagnitude compared with pesticide residues generated from the 2 1 -d EECs where volatilizationwas not considered (Table 17). Table 21. 60-d average estimated concentrationsof PCNB and its degradates in aquatic NB,

Page 31of 70 Surface Water (PgW

79 35 22 10 5.7

Filter Feeders Small Fish Medium Fish Large Fish Sediment Pore Water (PdJ-4

53 20 26 13 4.2

202 453 536 738 89 200 236 326 5 8 129 153 208 26 59 70 95 15 33 39 53Table

### 22. Estimated concentrations ofPCNB and its degradatesin aquatic organisms when considering surface water concentrations that account forvola~lization~

3.3.3. Comparison of Field Measured and Estimated Concentrations of PCNB and its degradatesin Fish Tissues Estimated concentrationsofPCNB and its degradates in fish range from 6.2 

### x lo4pgkgto 1.0 x lo7 pglkg (Table 17). These estimates differ by several orders of magnitude when compared to measured concentrations of PCNB (only) in field-collected fish tissues (range of 0.766-5.54 pgkg; see Section 3.3.1). These differences can be attributed to several factors,including: 1) Monitoring studies analyzed fish tissues for PCNB only. Given that PCTA has been identified as representing the majority ofPCNB residues (as much as 90%), it is likely that reported values for PCNB parent compound alone underestimate total PCNB residues of concern, which include PCNB and its degradates. 

### 2) Estimated concentrations of PCNB and its degradates are based on maximum use rates of PCNB as allowed by labels (considered current at the time the ecological risk assessment chapter for PCNB was written). Measured concentrationsof PCNB in field collected fish may be representative ofuse rates that were lower than maximum rates definedby labels. 3) Fish were not collected relative to temporal or spatialPCNB use. As such, residues in fish reported through this monitoring effort likely under-represent peak residues where fish habitat are adjacentto PCNB use sites. 4) Surface water column and benthic sedimentpore water EECs generatedby PRZMIEXAMS are based on the assumption that 100% of the watershed, associated with the water body that represents the habitat of the aquatic food web (of KABAM), is treated with PCNB at the same time. Larger watersheds often are not represented by a homogenous land cover, but rather are represented by a mixture of different land covers. Not all ofthe land covers of a watershed are likely to be use sites ofPCNB. Therefore, it ishighly unlikely that 100% of the watersheds associated with the water bodies where fish were collected were treated at the same time with PCNB. Furthermore, locations within the watershed that are treated are probably not treated every year, as is assumed for the PRZMEXAMS simulations. 5) Surface water column and benthic sediment pore water EECs generatedby PRZMEXAMS are based on the assumptionthat the receiving water body is a pond with a staticvolume no outflow. This could lead to higher estimated concentrations of PCNB and its degradates comparedto water bodies with outflows.

Page 32 of703.3.4. Estimated Concentrations of Contaminantsin Tissues ofAquatic Organisms The two contaminants HCB and PCB have estimated Log 

### Lw values (5.86 and 5.22, respectively) that are similar to each other and to those of PCNB and its degradates. In contrast, the 

### hw values of the PCDD and PCDF contaminants of technical PCNB are several orders of magnitude above PCNB and its degradates and its other contaminants(estimated Log 

### L, values range 7.92 

### - 9.50)


## . Therefore, the bioaccumulation potentials of HCB and PCB are considered separately from the PCDD and PCDF contaminants. 3.3.4.1. HCB and PCB The bioaccumulation of HCB and PCB (as contaminants of technical grade PCNB); in a freshwater aquatic ecosystem was estimated using KABAM run in default mode (see user's guide for hlldescription). This analysis does not account for bioaccumulation ofPCB formed as a degradate of PCNB. The 

### KO, and 

### LC values for HCB and PCB were estimated using EPISuite v.4.0 (USEPA 2008c) (Table 23). These values were used in KABAM to estimate the bioaccumulation of each chemical in aquatic food webs. Table23. Estimated 

### Knw. Kno and time to steadv state values for HCB and PCB. -.., 

### --

hexachlorobenzene

'~stimated using Kow method from EPISuite v.4.0 (USEPA 2008c) 3Estimated using KABAM. Contaminant pentachlorobenzene

The time to steady state for HCB and PCB is determined based on 

### KO,. This parameter is used to determine the appropriate averaging period of EECs in surface water and the benthic compartment. Based on the estimated time to steady state of HCB (48 d), the appropriate averaging period for the water column and benthic EECs is the annual 1-in-10 year value. For PCB, the estimated 48 d time to steady state falls between the 21-d and 60-d averaging periods used by the pe5 shell of PRZMfEXAMS. To be conservative, the 21-d EECs generated by PFUMJEXAMS are used for PCB. Water column and benthic EECs for HCB and PCB were determined based on the annual 1 -in-10year values generated for PCNB and its degradates ( Table 24 and Table 25, respectively). These EECs were multiplied by the maximum percent of each contaminant that is allowed by EPA in technical PCNB. As noted previously, the EPA allows a maximum of 500 ppm (0.05%) for HCB and 100ppm (0.01%) for PCB~, in technical PCNB. In this approach, it is assumed that PCNB, its degradates, HCB and PCB (which is also a degradate) have similar transport and degradation properties. The resulting estimated concentrationsof HCB and PCB are provided in Table 26 and Abbreviation HCB

2 Personal communication with Jill Bloom. Time to steady state3 Log K,,'

'~stimated using EPISuitev.4.0 (USEPA 2008c) PCB

Page 33 of70 KO: 5.86 5.22 5495 200 d 8492 48 dTable 

### 27, respectively.

Table25.1-in-10 year 21-d mean EECs (pg/L) forPCNB and its degradates aswell as PCB in the water column and benthic compartment of the standard pond. Table24.1-in-10 year annualmean EECs (pg/L) forPCNB and its degradates as well as

Table26. Estimated concentrations of HCB in tissues of aquatic organisms (base4 on maximum allowed level of contamination in technical PCNB). potatoes

Use turf cabbage peanuts cotton potatoes

Page 34 of 70 "Calculated as 0.05% ofEEC for PCNB +degradates (valuesin adjacentcolumn). 1.56 0.00078 1.90 

## 1 0.00095

*Calculatedas 0.05% ofEEC for PCNB

### +degradates(values in adjacentcolumn). Water column PCNB

### + degradates 110 37 5 5 11 16 Benthic PCB
0.011 0.0037 0.0055 0.0011 0.0016 PCNB 

### + degradates 56 28 2 1 4.6 13 PCB
0.0056 0.0028 0.0021 0.00046 0.0013Table 

### 27. Estimated concentrations ofPCB in tissues of aquaticorganisms (based on maximum allowed level of contamination in technicalPCNB).

3.3.4.2. PCDDs and PCDFs Small Fish MediumFish Large Fish

The bioaccumulation of PCDDs and PCDFs in a freshwater aquatic ecosystem was estimated using KABAM 

### run in default mode (see user's guide for hll description). The 

### KO, and 

### KO, values for PCDDs and PCDFs were estimated using EPISuite v.4.0 (USEPA 2008c) (Table 28). These values were used to determine input parameter values for KABAM to estimate the bioaccurnulation oftotal PCDDs and PCDFs in aquatic food webs. There is greater uncertainty in the bioaccumulation estimates for these contaminants oftechnical PCNB because KABAM is generally appropriate for chemicals with Log 

### &, values 24 to 

### I 8. All of the dioxins and furans that are considered contaminants, with the exception of Hexachlorodibenzofuran (HxCDF) have estimated Log 

### &, values >8. Uncertainty increases as the Log 

### KO, value increases above 8because the bioaccumulation model of KABAM (Arnot and Gobas 2004) has generally been validated using chemicals with Log 

### KO, values within the range of 4 - 8. Although predictions for a chemical with a Log 

### KO, > 8 are based upon extrapolations in KABAM's subroutines, the model is still expected to be useful for predicting bioaccumulation ofPCDDs and PCDFs. 0.116 0.150 0.244

Table 

### 28. Estimated

### K,, 

### KO, and time to steady state values for PCDDs and PCDlFs that represent contaminants of technicalPCNB.

Page 

### 35 of70 0.039 0.051 0.083 0.058 0.074 0.122 0.012 0.015 0.024 0.017 0.022 0.036'~stimated using EPISuitev.4.0 (USEPA 2008c) '~stimated using Kow method from EPISuitev.4.0 (USEPA 2008c) 3stimatedusing KABAM The time to steady state for each contaminant was determined based on 

### KO,. This parameter is used to determine the appropriate averaging period of EECs in surface water and the benthic compartment. All ofthe contaminants, with the exception ofPCB, require an annual I-in-10 year EEC to represent the appropriate averaging period (Table 28). Therefore, this averaging period (>1 yr) was selected to be representative of PCDDs and PCDFs that contaminate technical grade PCNB. The TEFs ofthe PCDDs and PCDFs that represent contaminantsoftechnical PCNB are provided in Table 29. For each PCDD and PCDF, the concentration of the chemical is multiplied by its TEF. The sum of the product for each PCDD and PCDF represents the toxicity equivalence concentration (TEC; Equation 1;USEPA 2008a). Equation 1. 

### TEC = 

### on cent ration, 

## *TEF,
Table 29. Measured concentrationsofPCDDs and PCDFs in technicalPCNB and toxicity equivalency factors (TEFs) for mammals for PCDDs and PCDFs that represent contaminants of technicalPCNB (TEFs from USEPA 2008b).



## I

1

Compared to 2,3,7,8-TCDD OCDD

1234678-HpCDF I. IYC+UI V.UI 3570

Based on the concentration of contaminants in the sample analyzed by EPA, the mammalian TEC is 0.51 ppb. The congeners 1,2,3,4,6,7,8-HpCDD, 1,2,3,6,7,8-HxCDF and 1,2,3,4,6,7,8- HpCDF make up the majority (80%) of the TEC. Therefore, these three congeners are used to generate a representative 

### &, (average =4.4~10~) for 

### PRZMIEXAMS and Log 

### KO, (range 7.92- 8.85) for KABAM. The TEC was multiplied by the use-specific maximum application rates on the label for PCNB to determine the amount of 2,3,7,8-TCDD equivalent PCDDs and PCDFs applied with PCNB. The PRZMIEXAMS input parameters for PCDDs and PCDFs used to derive surface water and pore water EECs are in Table 30 and Table 31.The resulting surface water 1 

### - 2.16E+02 

### ( 0.0003 

## 1 13%

1234789-HpCDF OCDF

Page 36 of 70 1.09E-01 2.28E+00 0.01 0.0003 4% 4%

### in-10 year yearly EECs (water and benthic) are in Table 32. The KABAM-estimated concentrations ofPCDDs and PCDFs are provided in Table 33 

### and Table 34.

Table 30. Use-specific input parameters used in PRZM for PCDDs andPCDFs.

1.5xlO*' ( 1 ( FL cabbage 

### I Aug 15 0.51 x10-' 

### I 1 

## 1 NC peanut 

## I April 15 0.10x10-~ 

### I 1 

### I MS cotton 

### 1 Auril 20 nade via a ground spraywith a spray drift fraction of 0.0 App, Method foliar spray ground spray; incorp. to 10cm 

### ** ground spray ground spray ground spray; incorp. to 10 cm 

### ** 1and an application efficiency of 0.99 - - - - 

### . * cabbage is a surrogate for all

### COG crops. 3Application rates representmaximum values allowedby product labels current at the time the ecologicalrisk assessment chapter (DP Barcode 291276)was conducted. 4 Based on USDA Crop Profiles information located athttp://pestdata.ncsu.edu/cropprofiles V1-d application interval **CAM =4
Table 31. Chemical-specific input parameters used in PRZMIEXAMS forPCDDs and PCDFs.

Table 32.1-in-10year surface water and pore water EECs (pg/L) ofPCDDs and 

### E?CDFS generatedby current version ofPRZM/EXAMS. Use ( Surface Water (pg/L) 

### I Sediment Pore Water (pg/L)



### Page 37 

### of70 7 Source Average of: 375 (HxCDF),409 (HpCDF), 425

(HpCDD), values calculatedusing EpiSuite v.4.0 Average of: 1.1 e-7 (HxCDF), 2.9e-8 (HpCDF), 2.7e-9 (HpCDD), values estimatedusing EpiSuite v.4.0 Average of: 6.8e-6 (HxCDF), 5.0e-6 (HpCDF),

1.4e-6(HpCDD),values estimatedusing bond method of EpiSuitev.4.0 Average of: 5.9e-5 (HxCDF), 1.0e-5 (HpCDF), 1.6e-5 (HpCDD), values estimatadusing EpiSuite v.4.0 Assume stable Assume stable Assume stable Assume stable Assume stable Mean of EpiSuitev4.0 values for HpCDD, HxCDF and HpCDF Parameter (units)
MolecularWeight (glmol)
Vapor Pressure (torr)
Henry's Law Constant (atm-m3-mol)

Solubilityin Water at 25'C (mg/L) Hydrolysis Half-life @pH7 (days) Aquatic Photolysis Half-life @pH 5 (days)

Aerobic Soil MetabolismHalf-life (days)

AerobicAquatic MetabolismHalf-life (days) Anaerobic Aquatic Metabolism Half-life (days) Soil Partition Coefficient(Kd;mL/g) Value
403

4.7 x10-~

4.5 x10-~

2.8x~o-~ 0 0 0 0 0 4.4XIO~

## I Turf 

## I Cabbage 0.84 ~10~' 0.23x10-" 

# 1

Table 33. Estimated concentrationsofPCDDs and PCDFs in aquatic organisms. Values generated using Log Kow =7.92. Peanuts Cotton Potatoes



### I Phytoplankton 

### 1 9.7x10-~ 

### 1 1.3~10.~ 

### 1 2.4x10*~ 

### 1 5.8 XIO-~ 

### 1 4.6 x10-~ 

### I 1.5x~O-~ 0.36x10e8 0.029xl0-'

- - - 0.43 ~10~" 0.097 x10-~ 0.0079 x10-'

Trophic Level

Table 34. Estimated concentrations ofPCDDs and PCDFs in aquatic organisms.Values generated using Log 

### KO,= 8.85. - - Zooplankton Benthic Invertebrates Filter Feeders Small Fish Medium Fish Large Fish Turf

3.4. Risks to Mammals, Birds, Terrestrial-phaseAmphibians and Reptiles Consuming Aquatic Organisms 8.9x~o-~ 9.0 X~O" 6.1 XIO-~ 2.2 x~o-~ 3.7 XIO-~ 9.4 x~o-~

Trophic Level Phytoplankton Zooplankton Benthic Invertebrates Filter Feeders Small Fish Medium Fish Large Fish

OPP compared EECs of PCNB and its degradates in tissues of aquatic organisms (Table 17) to chronic toxicity data for mammals and birds using the risk quotient (RQ) method to evaluate the risks of adverse ecological effects from PCNB and its degradates to non-target species. As discussed previously, chronicRQs are calculated by dividing exposureconcentrationsby chronic toxicity endpoints (i.e., NOAEL or NOAEC). The RQs are then compared to the Agency's established level of concern (LOC) to evaluate risks to non-listed and listed animals. The chronic risk LOC for both non-listed and listed species is an RQ value of greater than or equal to 1.0 OJSEPA 2004a). If RQ values exceed the 

### LOC, then the assessed use of PCNB has the potential to cause adverse chronic effects to non-target mammals, birds, terrestrial-phase amphibiansand reptiles that consume aquaticorganisms. Cabbage

Page 38 of 70

1.2x~o*~ 1.2x~o-~ 8.4 x10-~ 3.0xlOW5 5.1 xlo-' 1.3xlOV4

Turf 1.0x~o-~ 1.8x10b4 8.3 xlo" 5.8xlo" 8.3 XIO-~ 5.9 ~104 4.5 XIO-~ Peanuts

2.2 ~10'~ 2.2 x~o-~ 1.5x~o-~ 5.4XIO-~ 9.2XIO-~ 2.3 x10q4

Cabbage 1.4x1u6 2.4XIO-~ 1.1~10" 8.1 x10-~ 1.1XIO-~ 8.1 x10-~ 6.1 x10-~ Cotton Potatoes

5.2 x10-~ 5.3x10-~ 3.6x10-~ 1.3x~o-~ 2.2x~o-~ 5.6 xlo"

Peanuts 2.5 x10-~ 4.4 XIO-~ 2.1 x~o-~ 1.4x~o-~ 2.0 XIO-~ 1.4x~o-~ 1.1~104 4.2 x10'~ 4.3 x~o-~ 2.9xlu7 1.0x10-~ 1.8x10-~ 4.5 x10-~

Cotton 6.0x~o-~ 1.0X~O-~ 4.9 x10m6 3.4 ~10'~ 4.9x10-~ 3.5 x10-~ 2.6 x10-~ Potatoes 4.8 x10-' 8.4XIO-~ 4.0 x~o-~ 2.8XIO-~ 3.9x~o-~ 2.8XIO-~ 2.1x~o-~RQs for mammals and birds exposed to PCNB and its degradates on a chronic exposure basis through consumption of aquatic organisms are provided in Table 35 to Table 41. As discussed previously, RQs for birds are used as surrogates for terrestrial-phase amphibians and reptiles that consume aquatic organisms. The exposure component of the RQ values was calculated using KABAM v1

### .O. 3.4.1. Chronic Risks to Mammals from PCNB and its Degradates For chronic, dose-based exposures of mammals to PCNB and its degradates, RQs exceed the chronic risk LOC (1.0) for all default mammals (i.e., fog shrew, water shrew, rice rat, star-nosed mole, mink and river otter) across all assessed uses of PCNB (Table 

### 35). Dietary-based RQs also exceed chronic risk LOCs for all mammals modeled and for all uses of PCNB (Table 36). Although dietary-based RQ values are considerably lower than dose-based RQ values, the former do not take into account that different sized animals consume differing amounts of food. If dietary-based RQ values are adjusted to account for differential food consumption, the adjusted RQ value would likely approximate the dose-based RQ value.



### 1 rice ratistar-nosedmole 

### 1 126" 

### 1 62.4" 

### 1 42.7" 

### 1 18.5" 

### 1 12.5" 

### 1 Table 

### 35. RQs for chronic, dose-basedexposures to mammals consuming aquatic organisms which have accumulatedPCNB and its degradates. Values calculated using KABAM v1.0.



### I smallmink 

### 1 193" 

### 1 95.7" 

### 1 65.6" 

### 1 28.4" 

### 1 19.2" 

### 1 1 large mink 

### 1 213' 

### 1 106" 

### 1 72.5' 

### 1 31.4" 

### 1 21.2" 

### 1 TrophicLevel fodwater shrew Peanuts 33.6"

Table 36. RQs for chronic, dietary-basedexposures to mammals consuming aquatic Turf 98.7"

smallriver otter large river otter

- - organisms which have accumulated total 

### PCNB and its degradates. Values calculqtedusing KABAM v1.0. Cotton 14.6" Cabbage

49.0" Potatoes 9.8"

*RQ exceeds chronicLOC (RQ21) for listed and non-listedmammals. 229" 343"

TrophicLevel foglwatershrew



### I large river otter 

### 1 42.6" 

### / 21.2" 

### 1 14.4" 

### 1 6.3" 

### 1 4.D" 

### I 114" 171"

rice ratistar-nosedmole small mink large mink smallriver otter *RQ exceeds chronicLOC for listed and non-listedmammals. Turf 17.7"

The chronic toxicity component of the RQs for mammals is based on the level where no effects (NOAEL) to rats exposed to PCNB were observed in a 2-generation reproduction study (i.e., 1.2 mglkg-bwlday). At the LOAEL for the study (169 mglkg-bw), decreases were observkd in body weights ofoffspring and parents. Dose-based EECs calculated by KABAM for PCNB use onturf 78.0" 116"

18.5" 30.8" 30.8" 30.8"

Page 39 of 70 33.8" 

## 1 22.8" 50.3" 

## 1 34.2"

Cabbage

8.8" 9.2" 15.3" 15.3" 15.3" Peanuts 6.0" 6.3" 10.5" 10.5" 10.5" Cotton 2.6" Potstoes 1.8" 2.7" 4.6" 4.6" 4.6" 1.8" 3.1" 3.1" 3.1"and cabbage are sufficient to exceed the dose-based LOAEL for this study. This indicates that concentrations of PCNB residues in aquatic organisms are estimated to be above levels where effects to rats were actually observed in the laboratory. The concentration ofPCNB and its degradates in fish that is sufficient to be ofconcern for mink and otters is >3 mglkg (i.e., would result in a RQ that exceeds the LOC). For all uses ofPCNB, predicted concentrations of PCNB and its degradates in aquatic organismsbased onthe lowest Log 

### KO, (4.22) value reported for PCNB are still sufficient to exceed the chronic risk level of concern for mink and otter (Table 18 and Table 19). If RQs were generated for mammals using the 60-d EECs in Table 21, these values would be sufficient to exceed the chronic risk LOC for mammals across all modeled uses of PCNB (i.e., predicted concentrations in aquatic organisms exceed 3 mglkg). Therefore, the use of surface water and sediment pore water EECs with 21-d and 60-d averaging periods (which represents a bound of the 30-d time to steady state that is representative of PCNB and its degradates) yield the same conclusions that for all assessed uses of PCNB, predicted concentrations of PCNB and its degradates in aquatic organisms are sufficient to pose a risk of chronic effects to mammals. The number of days where the water column concentration is sufficient to result in concentrations of PCNB and its degradates in aquatic organisms that are of concern can also be considered. According to the KABAM user's guide, for a chemical with a Log 

### KO, of 5, estimates of pesticide concentrations in aquatic organisms are sensitive to changes in the water column EEC, but not to changes in the benthic EEC. Therefore, with the pore water EEC set to 0, the highest value was determined for the water column EEC that results in a chronic (dosebased) RQ that does not exceed the LOC. Based on the NOAEL of 1.2 mglkg-bw, this water column EEC is 0.32 pg/L. The number of simulated days (out of 10958) that result in water column EECs that exceed 0.32 pg/L for each use of PCNB are provided in Table 37.

Using the exposure values in Table 22 that account for volatilization, concentrations of PCNB and its degradates in aquatic organisms would be sufficient to exceed the chronic risk LOC for all assessed uses of PCNB for mammals (i.e., predicted concentrations in aquatic organisms exceed 3 mglkg). Therefore, although accounting for loss (from the application site and aquatic water body) of PCNB and its degradates through volatilization results in decreased predictions of PCNB and its degradates in aquatic organisms, the conclusions associated with the cllronicRQs for mammals and birds (Table 35 and Table 36) do not change. Table

### 37. Number of simulated days in 

### PRZMIEXAMSwhere water column

### EEC is at a level sufficientto exceed riskto mammals consuming aquatic organisms that have accumulated PCNB and its degradates.

Page 40 of 70 Use
Turf Cabbage Peanuts Cotton Potatoes # days where water concentrationis sufficient to exceedLOC 8695 9578 9584 8068 6348 % of total days where water columnEEC that is sufficient to exceed LOC 79% 87% 87% 74% 58%Based on this information, fog shrews, water shrews, rice rats, star-nosed moles, mi& and river otters consuming aquatic organisms that have accumulated residues of PCNB and its degradates have the potential to experience adverse chronic effects due to exposures to PCNB and its degradates in aquatic forage items. 3.4.2. Chronic Risks to Mammals from Contaminants 3.4.2.1.HCB and PCB For PCNB contaminants HCB and PCB, dose-based RQs were derived for a large river otter (assumed to eat 100% large fish) based on individual contaminant levels in those fish and toxicity data for PCNB. In this approach, it was assumed that HCB and PCB were equivalent in toxicity to PCNB. The large river otter was selected since it represents the highest (most conservative) RQ for mammals consuming aquatic organisms. The river otter 

### RQ for HCB resulting from PCNB use on turf exceeds the chronic risk LOC, suggesting potential for effects from the HCB contaminant when PCNB is used on turf (assumes HCB is present at 0.05% oftechnical PCNB). All other modeled uses of PCNB result in RQs for HCB that are below the chronic risk LOC, indicating a low potential for adverse chronic effects to mammals consuming fish (Table 

### 38). All modeled uses of PCNB result in RQs for PCB (as a contaminant) that are below the LOC. This indicates that the maximum level of PCB contamination allowed by the EPA (0.01% of technical PCNB) has a low potential for risk to mammals consuming fish (Table 38). Note that this conclusion does not consider exposure due to degradation of PCNB to PCB.
Table38. Chronic, dose-based RQs for large otter (most conservative RQs generatedby KABAM) exposed to HCB and PCB.


### I Turf 

### I 1.64* 

### 1 0.082 

### / Use 

## 1Cabbage 0.57 0.03 HCB

*ExceedsLOC (1.O) PCB

Peanuts Cotton Potatoes

3.4.2.2.PCDDs and PCDFs Estimated concentrations of PCDDs and PCDFs in aquatic organisms (Table 33 and Table 34) were used to determine potential chronic risks to mammals. These EECs were compared to chronic mammalian toxicity endpoints for 2,3,7,8-TCDD that were identified by the USEPA Office of Water (OW) for the Great Lakes Water Quality Initiative Criteria for the ~rbtection of Wildlife (USEPA 1995). As discussed previously in this assessment, OW defined a NOAEL of 0.75 0.25 0.13

Page 41 of 70 0.04 <0.01 0.0 10.001 pglkg-bwlday (1x10-~ mglkg-bwlday) for reproductive effects to mammals exposed to 2,3,7,8-TCDD in food. This NOAEL was based on reduced fertility in first (fi) and second generation (fi) rats exposed to a LOAEL of 0.01 &kg-bwlday reported by Murray et al. 1979. When this NOAEL is used in KABAM, chronic, dose-based mammalian RQs for PCDDs and PCDFs representing contaminants of PCNB are sufficient to exceed the chronic risk LOC (1.0) for all modeled mammals for PCNB uses on turf, cabbage, peanuts and cotton (Table 39 and Table 40). In addition, estimated levels ofPCDDs and PCDFs resulting from PCNB use on turf, cabbage, peanuts and cotton are sufficientto exceed the LOAEL (i.e., 0.01 yglkg-bw/day) for reproductive effects for some mammals. Therefore, for PCNB use on turf, cabbage, peanuts and cotton, PCDDs and PCDFs residues in technical PCNB (based on the levels measured by EPA) pose a risk ofreproductive effectsto mammalsthat consume aquaticorganisms. For PCNB use on potatoes,PCDD and PCDF levels in aquatic organismsare sufficientto exceed the chronic risk 

### LOC only for the large river otter when considering the lower Log KO, value (7.92) within the range of 

### KO, values representative of PCDDs and PCDFs that contaminate PCNB.
Table 

### 39. Chronic, dose-basedRQs for mammals (that consume aquatic organisms) exposedto PCDDs and PCDFs. RQs based on use ofLog 

### K, =7.92. Species

Table 

### 40. Chronic, dose-based RQs for mammals (that consume aquatic organisms) exposedto PCDDs and PCDFs. RQs based on use ofLog 

### &, =8.85. fogiwater shrew rice ratlstar-nosed mole small mink large mink small river otter large river otter Turf

*RQ exceeds LOC (1.0). 25* 42

### * 120" 130" 140X 380"

Species Cabbagc

foglwater shrew rice ratlstar-nosed mole small mink

3.4.3. Chronic Risks to Birds, Terrestrial-phase Amphibians and Reptiles from PCNB and its Degradates 3.4" 5.8" 16" 18" 19" 52"

Turf

large mink small river otter large river otter

Page 42 of70 Peanuts

23

### * 25" 18* 6.2" 

### lo* 29" 32* 34" 93

### *

Cabbage

*RQ exceeds LOC (1.0). 20" Cotton

3.2" 3.5* 2.5" 2.8" 

## 1 2.0"

pp

### 1 3.0" Potatoes 1.5" 2.5" 6.9" 7.6" 8.2" 22"

Peanuts

1.2" 1.3" 5.4" 0.12 0.20 0.56 0.61 0.66 1.8"

5.7" 6.3" 4.5" 0.10 0.10 22

### * Cotton

18" Potatoes 1.4" 1.5* 1.1" 0.1 1 0.12 0.09

2.5" 4.4" 1.1" 0.09Dietary-based RQs for turf exceed the chronic risk LOC (1.0) for birds represented by small osprey and white pelicans (which have a diet comprised entirely of fish; Table 41). Chronic RQs are based on the level (NOAEC) where no effects to birds were observed inreproduction studies. Birds are assumed to be surrogates for terrestrial-phase amphibians and reptiles. Therefore, PCNB use on turf has the potential to result in chronic effects to birds, amphibians and reptiles that consume aquatic organisms that have accumulatedPCNB and its degradates. Dietary-based RQs for birds from use of PCNB on cabbage, peanuts, cotton and potatoes do not exceed the LOC (Table 41). Therefore, for PCNB uses other than turf, effects on growth and reproduction are not expected in birds, amphibians andreptiles that consume aquatic organisms.

Table 41. RQs for chronic, dietary-basedexposures to birds consuming aquatic organisms which have accumulated 

### PCNB and its degradates. RQs for birds sewe as surrogates for



### 1 Cranes 

### 1 0.8 

### 1 0.4 

### 1 0.3 

### 1 0.1 

### 1 0.1 

### 1 terrestrial-phase amphibiansand reytiles.Exposure calculatedusing

### KABAM (v1.0).



### ( Herons 1 .O 0.5 0.3 0.1 0.1 TrophicLevel sandpipers 

## I Rails I I I I I Turf 0.7 Cabbage 0.4
0.9

RQs for PCNB and its degradates arebased on a Log 

### KO, value of 5.0. This leads to uncertainty in bioaccumulation and associated risk estimates. This uncertainty can be explored by considering the lowest and highest reported Log 

### KO, values for PCNB, which are 4.22 and 5.3, respectively. For all uses of PCNB, predicted concentrations of PCNB and its degradates in aquatic organisms based on the lowest Log 

### KO, (4.22) value reported for PCNB are not sufficient to represent a chronicrisk to birds for any assessed use of PCNB. For the highest Log 

### KO, value for PCNB (5.3), concentrations ofPCNB and its degradates in aquatic organisms are sufficient to be of concern for birds for use ofPCNB on turf,peanuts and cabbage. If RQs were generated for birds using the 60-d EECs in Table 21, these values would be sufficient to exceed the chronic risk LOC for birds for the use of PCNB on turf. Therefore, the use of surface water and sedimentpore water EECs with 21 -d and 60-d averaging periods (which represents a bound of the time to steady state of uptake of PCNB and its degradates) yield the same conclusion that for use of PCNB on turf, predicted concentrations of PCNB and its degradates in fish are sufficient to result in adverse chronic effects to birds and by extension to terrestrial-phase amphibiansand reptiles. Peanuts 0.3

small osprey white pelican

Using the exposure values in Table 22 that account for volatilization, PCNB and its degradatesin aquatic organisms would be sufficient to exceed the avian chronic risk LOC from use of PCNB on turf



### . Therefore, although accounting for loss (from the application site and body) of PCNB and its degradates through volatilization results in decreased 0.4

*RQexceeds chronic LOC for listed and non-listed birds. 0.6 0.8 1.2* 1.7*

Page 43 of 70 Cotton 0.1
0.3 0.1 Potatoes 0.1
0.1
0.4 0.6 0.2 0.3 0.1 0.2PCNB and its degradates in aquatic organisms, the conclusions regarding potential risks to birds (Table 41) do not change.

3.4.4. Chronic Risks to Birds, Terrestrial-phase Amphibians and Reptiles from Contaminants 3.4.4.1. HCB and PCB Chronic, dietary-based RQs for all of the avian surrogate species used in the KABAM model exposed to the PCNB contaminants HCB and PCB fkom PCNB use on turf are at least 4 orders of magnitude below the chronic risk LOC (1.0). This indicates that for all uses of PCNB, the maximum levels of HCB and PCB are not expected to cause effects on growth and reproduction ofbirds, terrestrial-phase amphibiansandreptiles. 3.4.4.2. Polychlorinated-dibenzodioxins and -dibenzofurans Chronic avian toxicity data identified by OW for 2,3,7,8-TCDD were not considered in this assessment because the birds were dosed intraperitoneally and not through the diet. Therefore, potential risks to birds, terrestrial-phase amphibians and reptiles have not been assessed for PCDDs and PCDFs.

4. Bioaccumulation ofPCNB and its Degradates in Terrestrial Organisms and Associated Risks Pesticide bioaccumulation in terrestrial ecosystems has rarely been incorporated into past ecological risk assessments conducted by OPP. In previous ecological risk assessments of PCNB, bioaccumulation ofPCNB and its degradates was not considered. At this time, OPP does not have specific data requirements or sufficiently vetted tools to estimate pesticide bioaccumulation in terrestrial ecosystems. Methods related to assessing bioaccumulation in terrestrial ecosystems are not as developed as those available for aquatichabitats.
In regard to factorsthat EPA can consider when identifying terrestrialbioaccumulation potential of a pesticide, the SAP indicated that a chemical's octanol-water and octanol-air partition coefficients (KO, and KO,, respectively) are important. As discussed in USEPA 2008a, several authors, including: Kelly and Gobas (2003), Armitage and Gobas (2007) and Kelly et al. (2007) concluded that chemicals with Log I(OA>5 and Log I(Ow>2may biomagnify in terrestrial food chains. The SAP also indicated that metabolism of pesticides by organisms should also be considered, since metabolism of a chemical may change the likelihood of a chemical to bioaccurnulate. Currently,OPP uses a simplefugacity approach (described below) for estimating concentrations of PCNB and its degradates in earthworms inhabiting fields treated with PCNB, as an initial indicationofbioaccumulationpotential.

Page 44 of 704.1. Accumulation ofPCNB and its Degradatesin Soil Because PCNB and its degradates are persistent in soil (with an upper 90% confidencebound on the mean aerobic soil metabolism half-life of 1052 days) and do not have a tendency to leach from soil (non-sand 

### Kd values range 15.5 

### - 210 mL/g, 

### MRID 41648201), an analysis was conducted to characterize the levels of PCNB and its degradates in the soil of a treated site after 30 years of applications.In order to accomplish this, PRZM was run using the input parameters for PCNB and its degradates as defined in Table 42 and Table 43. The studies and analysis that form the basis for these values are more thoroughly described in the environmental fate and ecological risk assessment chapter written in support of the 

### RED for PCNB 

### (DP Barcode 291276).

0.99 2 Cabbage is a surrogate for all cole crops. 3Application rates representmaximum values allowedby product labels current at the time the ecological risk assessment chapter (DP Barcode 291276)was conducted. 4 Based on USDA Crop Profiles informationlocated at http://pestdata.ncsu.edu/cropprofiles Table 

### 43. Chemical-specific input parameters for PCNB and its degradates used in PRZM. Parameter (units) MolecularWeight (dmol) - .- 

# I Vapor Pressure (Tori-) , I

42112801

Aerobic Aquatic Metabolism Half-life (days) 

### I 2248 

### I MRIDs42911902,41384501,41713202, 1.13x lo4 Henry's Law Constant (atm-m5-mol) Solubilityin Water at 25OC (ppm) Hydrolysis Half-life @pH 7 (days) Aquatic Photolysis Half-life @pH 5 (days) Aerobic Soil Metabolism Half-life (days) Value 295.3 Product chemistry data

input value is 2X the aerobic soil metabolism half-life input value fortotal residues asper input parameter guidance

input value is two times the anaerobic soil metabolism half-lifevalue Of 1002 days, calculatedfortotal residues as per inputparameter guidance 4 lowestnon-sand Kd Source Product chemistrv data
4.42x 10" 0.44 stable

1.83 1124

## '

AnaerobicAquatic Metabolism Half-life (days) Soil Partition Coefficient(Kd;mL/g)

Page 45 of 70 Productchemistry data Product chemistry data MRIDs 40865301,40972601 MRIDs42606201,42606202,42336201 MRIDs 42911902,41384501,41713202,

representsthe 90' percentile ofthe upper confidencebound on the mean of 2 half-lifevalues; fortotal residues 2004 15.5 421 12801 MRID 41384301 MRlD 41648201The resulting estimates of PCNB and its degradates in soil based on PCNB use 

### on cabbage, cotton, peanuts, potatoes and turf are depicted in Figure 

### 3, which indicates that PCNB and its degradatesare expected to increase over time in soils where PCNB is applied. It is assumed that the annual average soil concentrationis representative ofthe steady state concentration of PCNB and its degradates in soil (Table44).

simulation day -Cabbage - Cotton Peanut Potatoes ---Turf Figure 3. Estimated concentrations of PCNB and its degradatesin soil of cabbage, cotton, peanut, potato and turf fields treatedwith ofPCNB.



## I Cabbage 55 Table 44. Average of annual averages (30years) of estimated concentrations ofPCNB and its degradatesin soil for differentuses ofPCNB. Use

4.2. Bioaccumulation Potential Average of annual averages (mg/m3)

Peanuts Cotton Potatoes

As discussed above, Kelly and Gobas (2003), Armitage and Gobas (2007) and Kelly et al. (2007),concludedthat chemicals which do not undergo substantial metabolism within organisms and have >lo5 and KO, >lo2 have the potential to bioaccumulate and biomagnify in terrestrial food chains. For example, Kelly and Gobas (2003) estimated biomagnifications factors for HCB (Log KOA = 7.1, Log KO, = 5.5) ranging 5.4-41.1 for male wolves. Based on the 27 5.3 14

Page 46 of70 Turf 10estimated (log) 

### KOA and

### I?, values for PCNB and its individual degradates, which are provided in Table 45, PCNB and its degradates have thepotential to biomagnify in terrestrial ecosystems.

A simple fugacity approach is used in this assessment to estimate concentrations of PCNB and its degradates in earthworms inhabiting fields treated with PCNB as an initial indication of bioaccumulation potential. This approach is explained in detail in Appendix C. Using PRZMestimated concentrations of PCNB and its degradates that are representative of steady state (average of annual averages), concentrations of PCNB and its degradates in earthworms range from 0.21 to 2.2 mglkg (Table 46). These concentrations are two orders of magnitude higher than estimated concentrations in the soil in which the earthworms live, indicating that PCNB and its degradatescan accumulate in soil-dwelling organisms inhabiting fieldstreated with PCNB. Table 45. Estimated Log KOA and Kow values for PCNB and its degradates. Residue pentachloronitrobenzene pentachloroanilinel pentachlorothioanisolel pentachlorobenzenel pentachlorophenol pentachlorothioanisole sulfoxide pentachlorothioanisole sulfone

Table 46. Estimated concentrations ofPCNB and its degradatesin soil and in earthworms.



### I Cotton 

### 1 0.0032 

### 1 0.21 

### 1

'~ajor environmental degradate Estimated using EPISUITE v. 4.0 (USEPA 2008c) Abbreviation PCNB PCA PCTA PCB PCP PCTASO PCTAS02

Use Turf Cabbage
.d I - - I

Potatoes 0.0085 0.55 

## I *Calculated using average of annual averages reported in Table 44 and converting them using th8 soil bulk density (1650 kg soil/m3). Peanuts

4.3. Metabolism of PCNB in Terrestrial OrganismsLog ~0.4~ 7.4 9.6 8.7 6.7 11 11 8.7

Concentrationin soil (mg/kg)* 0.0061 0.033

The 

### HED Metabolism Assessment Review Committee (MARC) met on April 16'~~ 2003 to determine the residues of concern and the PCNB tolerance expression for plants and livestock, as well as degradates of concernin water. The following text, from the MARC memo3, summarizes the findingsofthe review: Log

### KO$ 5.O 4.3 5.8 5.2 4.7 3.7 3.8

Concentration in earthworms (mg/kg) 0.39 2 2 0.016

3 Pentachloronitrobenzene (PCNB). (List A, CaseNo.0128) The Outcome of the HED Metabolism Assessment Review Committee Held on April 16th,2003 to discuss residues ofconcern in risk assessment and tolerance expression ofPCNB. Chemical 056502. Mohsen Sahafeyan & Laurence Chitlik. May 27th,2003 1.1

Page 47 of 70The MARC reviewed the major and minor metabolites of pentachloronitrobenzene (PCNB) identified in three plant metabolism studies (peanuts, potatoes, and cabbage), livestock (ruminant and poultry) metabolism study, rotational crop studies (lettuce,turn* roots and tops, and wheat), available field trial data, and information on environmental persistence and degradation of PCNB. The 

## URC also reviewed the available rat metabolism studies. For the primary crops,plant metabolism studies onpeanuts, potato, and cabbage [study deemed unacceptable] indicated that the major ident@ed radioactive residues (i.e. 210% total radioactive residue or TRR) were PCNB, S- (pentach1orophenyl)malonycysteine (PCP-MalCys), N-malonyl-S-(tetrach1oroaminophenyl)- cysteine, tetrachlorophenyl methyl sulfoxide 

### (TCPM sulfoxide), and tetrachlorophenyl methyl sulfone (TCPM sulfone). Other residues comprising 210% of the TRR were not identzfied or characterized in the cabbage study. However, for peanutfive metabolites and for potato thirty-six metabolite residues were identified.As all ofthe identifiedplant metabolites of PCNB in primary crops arepoly-chlorinatedphenyl compounds, all ofthese compounds (including minor metabolites) are of concern. For rotational crops, numerous metabolites were identijied in just about all cropparts studied in the confined rotational cropstudy. The crop parts studied included: turnip root and tops from 365 days after soil treatment (DAT), lettuce (30, 120, and 365DAT), wheat forage (30 and 120 DAT), wheat grain (30, 120, and 365 DAT), and wheat straw (120 DAT).As all ofthe identified metabolites in rotational crops are poly-chlorinatedphenyl compounds, all ofthese compounds (including minor metabolites) are ofconcern. Studies concerning the metabolism of PCNB in lactating goats and poultry were submitted. The major identged metabolites in ruminant tissues included PCA, pentachlorothiophenol (PCTP), tetrachlorothioanisole (TCTA), N-(pentachloroaniline) glucuronide (PCA-Gluc), and glucuronide of

### N-hydroxypentachloroaniline (2vOHPCAGluc). The major identified metabolites in poultry tissues included PCNB, PCA, pentachlorothiophenol (PCTA), pentachlorothioanisole sulfoxide (PCTA sulfoxide), TCA sulfoxide, tetrachlorophenyl methyl sulfone (TCP methyl sulfone) and tetrachloroaniline methyl sulfoxide (TCA sulfaxide isomers).As all of the identified metabolites arepolychlorinated phenyl compounds, all of these compounds (including minor metabolites) are ofconcern. In summary, available studieswith terrestrial plants (i.e., crops) and animals indicate that PCNB is metabolized by terrestrial organisms; however, all metabolites that were identified were polychlorinated phenyl compounds and deemed by 

### HED to be of concern. The effect of PCNB metabolism on the overall bioaccumulation in terrestrial organisms is unknown; however, metabolism ofPCNB does not necessarily render the degradates less toxic than theparent. 4.4. Risks to Mammals, Birds, Terrestrial-phase Amphibians and Reptiles Consuming Earthworms

Page 48 of 70PCNB is classified aspractically non-toxic to mammals and birds on an acute exposure basis. By assuming equivalent toxicity of PCNB and its degradates, the likelihood of mortality in these animals from acute exposures to PCNB and its degradates is considered low. Longer-term concentrations of PCNB and its degradates in earthworms (0.2 1-2.2 mglkg; Table 46) are below the chronic toxicity endpoints for mammals (i.e., NOAEC = 24 mglkg) and for birds, terrestrial-phase amphibians and reptiles (i.e., NOAEC = 600 mglkg). Therefore, it is unlikely that these animals will be subject to risk fkom chronic exposures to PCNB and its degradates as a result of consuming earthworms on fieldstreated with PCNB. This assessment only considers accumulation of PCNB and its degradates in one trophic level and the subsequent risks to animals consuming earthworms (i.e., vermivores). If PCNB and its degradates subsequently accumulate in vermivores, such as voles and robins, predators of these vermivores (e.g., foxes, hawks) may be exposed to even higher levels of PCNB and its degradates than are predicted in earthworms. Since OPP has no tool available to assess bioaccumulation in terrestrial food webs (beyond earthworms), the extent of this accumulation cannot be quantified at this time. Therefore, risks to higher trophic level animals consuming terrestrialanimals cannot be precluded.

5. Long Range TransportPotential (LRTP) ofPCNB and its Degradates The SAP advised the Agency to consider a holistic approach utilizing all available lines of evidence to evaluate the LRTP of persistent pesticides. In addition to using travel distance to characterizeLRTP of a pesticide, they also suggested that EPA include the evidence of sources and sinks ofpersistent pesticides in the ecosystem. This requires going beyond simple ranking of the long range transport potential of chemicals and providing a more quantitative analysis of pesticide transport to air from a use site and transport away from sourceregions. As a short-term solution to assessing the LRTP of a chemical, the SAP suggested that EPA employ a tiered approach: o Tier 1: Determine ifthe estimated (EPISUITE:AOPWIN) or measured atmospheric degradation half-life is great&than 2 days o Tier 2: Use the OECD Screening Tool to calculateoverall persistence, travel distance and transfer efficiency for the compoundsof interest and compare outputs to those of known persistent organic pollutants (POPS). o Tier 3: Use more sophisticated models (e.g., GloboPOP)to assess LRTP. In this assessment, the LRTP of PCNB and its degradates is assessed by considering available data on PCNB volatilization, by evaluating available monitoring data, and by using the Tier 2 methodology recommended by the SAP. 5.1. VolatilizationData PCNB is a moderately volatile compound that can be expected to dissipatethrough volatilization. Volatilization is a more significant route of dissipation of the parent and the PCA degradate when PCNB is not incorporated into the soil at application. This will occur when PCNB is

Page 49 of70applied as a foliar spray (e.g., to turf) or is applied by chemigation through overhead sprinkler irrigation (e.g., to potatoes). Based on its vapor pressure (1.13 x 

### 1 

## o4 tow @25OC), PCNB is expected to existprimarily in the vapor phase while in the atmosphere. Submitted data from a laboratory volatility study (MRID 41178001) showed that maximum volatilization ofPCNB residues occurred within 24 hours oftreatment. In a field volatility study (MRID 4375 1101),volatilizedPCNB and PCA were both at their observed maximums on Day 0 and declined throughout the rest of the 13-day study. It should be noted that large amounts of rain fell during study days 3 to 9 may have altered the volatilizationrate relative to that which might otherwise have occurred. Casely (1968) observed that PCNB may volatilize more from moist or saturated soils relative to dry ones due to decreased adsorption in the wetter soils. In this study, greater than two thirds of the approximately 80% of applied PCNB was lost due to volatilization from soil during 10 months ofincubation, with the remaining losses attributed to microbial degradation. Large Henry's Law constants for the degradates PCA, PCTA, PCB and PCP (onthe order of to atm/m3-mol) indicate that volatilization may also be an important environmental fate process for these compounds as well. 

### 5.2. Monitoring Studies Monitoring studies reported in the literaturethat involved PCNB included studies conducted in Canada where PCNB was detected in air over Saskatchewan (SK). PCNB was detected in 10 of 1 1 samples (at 0.01 

### -1.60 ng/m3)collected during a 3-month period in the summer of 1994over Regina, SKY and in 2 of 5 samples collected during that time over Waskesiu, SK (Table 47). The compound was not detected in any of 7 samples collected over Yellowknife, SK. The authors indicated that the registered uses of PCNB in Canada at that time (i.e., ornamentals, ginseng and turf)were not "major crops" grown in thatpart of SK (Thompsonetal., 1997). Table 47. Measured concentrationsofPCNB in air samples collected at areas removed from anr~lication sites.

Waskesiu, Saskatchewan Mount Revelstoke national Park, British Columbia

In another study that was conducted in Canada, PCNB was detected in air samples collected from 3 national parks in 2003 and 2004. At Mount Revelstoke National park, measured concentrationsranged 6-17 pg/m3. At Yoho National park, measured concentrationsranged 2-5 pg/m3. At Observation Peak in Banff National Park, measured concentrations of PCNB ranged 0.4-1.3 pg/m3(Daly et al. 2007; Table 47). Yoho National park, British Columbia Banff National Park, Alberta

Page 50 of70 Summer 1994

2003-2004 2003-2004 2003-2004 30-380 6-17 Thompsonet al., 1997 Daly et al. 2007 2-5 0.4-1.3 Daly et al. 2007 Daly et al. 2007The detection of PCNB in the atmosphere over areas in which the pesticide was ,not used is evidence of the possibility for long-rangetransportofthe compound. Available monitoring data for the major degradate PCB are not presented here as PCNB is not the single source for these compounds in the environment and the available monitoring data could not be linked to the use of PCNB. Air monitoring data could not be located for PCTA and PCA. Measured concentrations of PCNB, PCTA and PCA in soil, sediment and biota located in areas removed from treatment siteshave not been identified. 

### 5.3. Modeling Long-Range Transport Potential The "OECD Pov and LRTP Screening Tool" (version 2.0~) was used in evaluating the overall persistence (Pov), and LRTP of PCNB and its major degradates. The OECD Tool requires estimated degradation half lives in soil, water and air, and partition coefficients between air and water and between octanol and water as chemical-specific input parameters to calculate persistence and the metrics ofLRTP.
In the OECD tool, overall persistence is estimated based on a chemical's degradation rate constants in soil, water and air. Theresulting value represents the combined effect ofdegradation in every medium (soil, water, air) and represents the overall degradation of the chemical in the environment; it is determinedby the slowest responding medium (Scheringeret al.,2006). The LRTP of a chemical is based on two metrics: the characteristic travel distance (CTD) and the transfer efficiency (TE). CTD represents the potential of a chemical to be transported over long distances in air or water. In the OECD Tool, CTD is the distance at which the concentration of chemical decrease to 37% due to transport of chemical by a constant flow of air (wind speed of 0.02 mls) or water (ocean water circulation speed of 0.02mIs (Scheringer et al., 2006). For example, volatile chemicals that are highly persistent in air have high CTD values. TE is a dimensionless metric of the potential for atmospheric transport and deposition of parent compound in terrestrial and aquatic environments of a remote region (Wegmann et al., 2007). It is a ratio between the depositional flux (mollday) in remote region and emission 

### fldx from the source area. TE values greater than 100% are possible since some chemicals may undergo several cycles of deposition and revolatilization during their residence time in the environment (i.e.,the "grasshopper effecty'; Wagmannet a1

### ., 2007). Results fiom the OECD Tool do not indicate absolute loading of pesticides in the environment but help to compare the inherent characteristics with reference pesticides identified by the Stoclcholm Convention as Persistent Organic Pollutants (POPS) according to their overall persistence, CTD and TE. In this case, Aldrin and HCB are used as reference chemicals. Modeling results for PCNB and its (major) degradates are compared to those of aldriq and HCB. HCB was selected as a reference POP since it has a similar structurecompared to PCNB and it is

4 Available online at: http://www.oecd.org/documentl17/0,3343,en~2649~34373~40754961~1~1~1~1,00.html
Page 51 of70a contaminant of technical PCNB. Input parameters for aldrin, HCB, PCNB and its major degradates are provided in Table 48.

2Calculatedusing EPISUITEv.4.0. 3~stimated using Aopwin ofEPISUITE 4Input parameterto PRZWEXAMS for aerobic aquatic metabolism half-life (Table 43) 5PRZMJEXAMS input parameter for aerobic soil metabolism half-life (Table 43) Table 48. Physicochemical and environmental fate propertiesused as input for estimating overall persistence and long-range transport potential for selectedPOPSand PCNB and its major degradates using the OECD Tool.

By comparison, PCNB and its degradates have similar overall persistence compared to HCB, and longer overallpersistence compared to aldrin (Table 49). Name of Chemical

The CTD ofPCNB (1

## o4km) and PCB (1

## o4krn) are on a similar order ofmagnitude compared to HCB (10~-10'

### km). CTD values for PCA and PCTA an order of magnitude lower than that of PCNB; however, the CTD of PCNB and its major degradates exceed that of aldrin by at least 2 orders of magnitude (Table 

### 49). Based on these model results, PCNB and PCA have similar LRTP compared to HCB. PCNB and its major degradates have greater LRTP than aldrin. The TE of PCNB (235%) is on a similar order of magnitude compared to HCB (229-11,300%). TE values for PCNB's major degradates are 1-3 orders ofmagnitude lower PCNB. Compared to aldrin, PCNB has an estimated TE that is 3 orders of magnitude greater. PCA and PCTA have estimated TE values that are 1 order of magnitude greater than aldrin. PCB has a TE that is 2 orders of magnitude greater than aldrin (Table 49). Based on these model results, PCNB has a similar LRTP compared to HCB. PCNB and its major degradates have similar or greater LRTP than aldrin. Table 49. Overall persistence and characteristictravel distances generated using the OECD Tool. Molecular Weight Log KAw LogKO,

P 6.38-6.86 -1.57-(-1.10)

Page 52 of70 'parameter values based on reference chemical data in OECD tool. 

### Olrs) 0.905-9.05 7134-71340 147g3 96.g3 106~ 2220~ HCB PCNB PCA PCTA PCB

Chemical Half life in Air ( hrs) 846-8460 10800-108000 540004 540004 540004 540004 284.8 295.3 265.4 296.4 250.3

Overall Persistence (Days) (hrs) - 1210-12100 10800-108000 ,27000~ 270005 270005 27000' Half life in Water Halflife in Soil

5.49-5.97

5.03~ 4.~2~ 5.~2~ 5.222

CharacteristicTravel Distance (km) -1.62-(-1.14) -2. 742 -4.762 -2.84' -1.54~

Transfer Efficiency (%)

### 6. Summary and Conclusions Aldrin HCB PCNB PCA PCTA PCB

This assessment investigatedinfluences on previous risk conclusions attributed to assumptions of PRZMIEXAMS as these assumptions relate to persistent chemicals. The results of this assessment indicate that inclusion of pesticide burial, alteration of equilibrium partitioning of PCNB between aqueous and sorbedphases (on entering soil particles) and mass transfer between the water column and the benthic compartment do not alter the risk conclusions of the previous ecological risk assessment for PCNB that was conducted for the 

### RED. Therefore, use of PCNB poses acute and chronic risk to freshwater fish and invertebrates, acute risk to estuarinelmarine invertebrates,and chronic riskto estuarinelmarinefish and invertebrates. This assessment expands upon previous conclusions that PCNB and its degradates bioaccumulate in aquatic organisms. This is accomplished using available bioconcentration data for PCNB and modeling results from KABAM. The results of this assessment indicate that PCNB and its degradates and contaminants accumulate in tissues of aquatic organisms. Mammals consuming aquatic organisms have the potential to experience chronic effects due to exposures to PCNB and its degradates in aquatic forage items from uses of PCNB on turf, cabbage, peanuts, cotton and potatoes. Use of PCNB on turf poses a risk of chronic effects to birds, terrestrial-phase amphibians and reptiles consuming aquatic organisms. Contaminants of technical PCNB, including hexachlorobenzene and polychlorinateddibenzodioxins and polychlorinated dibenzofurans are also expected to bioaccumulate in aquatic systems. These contaminantspose risk of chronic effectsto mammals consuming aquaticorganisms. 7 1.7-689 607-6040 1400 2600 1490 1073

In previous ecological risk assessments of PCNB, bioaccumulation of PCNB and its degradates interrestrial organisms was not considered. Based on the estimated octanol-air and octanol-water partition coefficients for PCNB and its degradates, PCNB and its degradateshave the potential to bioaccumulate in terrestrial ecosystems. Estimated concentrations of PCNB and its degradates in earthworms are two orders ofmagnitude higher than concentrationsin soil,indicatingthat PCNB and its degradates can accumulate in soil-dwelling organisms inhabiting fields treated with PCNB. Available studies with terrestrial plants (i.e., crops) and animals indicate that PCNB is metabolized by terrestrial organisms; however, all metabolites that were identified were polychlorinated phenyl compounds, which are oftoxicological concern. At this time, OPP has no tool available to assessbioaccumulation interrestrial foodwebs (beyond earthworms). Therefore,the extent of bioaccumulation of PCNB in terrestrial ecosystems cannot be quantified bv EFED at this time and risksto terrestrialanimals cannotbe precluded.

Page 53 of 70 62.7-188 94900-6 16000 24400

3900 2131 43400 0.001-0.19 229-11300 235 2.65 2.11 71.5In additionto bioaccumulation, this assessment considers the ability of PCNB and its degradates to move to non-target sites via long range transport. The volatility of PCNB coupled with its likely persistence in the atmosphere allow for potential long-range atmospheric transport of PCNB. Detections of PCNB in the atmosphere over areas in which the pesticide was not used provide evidence of the possibility for long-range transport. Modeling indicates that PCNB has comparable or higher long range transport potential compared to chemicals that are known to move via long range transport.

7. References Cited Armitage, J.M. and F.A.P.C. Gobas. 2007.A terrestrial food-chain bioaccumulationmodel for POPS.Environmental Scienceand Technology, 4 1(11): 40 19-4025. Amot, J.A. and F.A.P.C. Gobas. 2004. A food web bioaccumulation model for organic chemicals in aquatic ecosystems. Environmental Toxicologyand Chemistry, 23 (10): 2343-2355. Casely, J.C. The loss of three chloronitrobenzene fungicides from the soil. 1968.Bull. Environ. Contam. Toxicol. 3:180-193. Daly, G.L., Lei, Y.D., Teixeira, C., Muir, D.C.G. and F. Wania. 2007. Pesticidesin Western CanadianMountain Air and Soil. Environmental Scienceand ~echnolog~, 41:6020-6025. Freitag, D., J.P. Lay, and F. Korte. 1984. Environmental Hazard Profile

### - Test Results as Related to Structuresand Translation into the Environment. In: K.L.E.Kaiser (Ed.), QSAR in Environmental Toxicology, Proc.of the Workshop held at McMaster University, Hamilton, Ont., Aug.16-18, 1983, D.Reide1 Publ.Co., Dordrecht, Netherlands :1 1 1 

### -131. Freitag, D., H. Geyer, A. Kraus, R. Viswanathan, D. Kotzias, A. Attar, W. Klein, and F. Korte. 1982. Ecotoxicological Profile Analysis VII. Screening Chemicals for Their Environmental Behavior by Comparative Evaluation.Ecotoxicol.Environ.Saf.6:60-8 1 Geyer, H., G. Politzki, and D. Freitag. 1984. Prediction of Ecotoxicological Behaviour of Chemicals: Relationship Between N-OctanolIWater Partition Coefficient and Bioaccumulation of Organic Chemicals by Alga Chlovella. Chemosphere 13(2):269-284 Grant DL, Phillips WEJ, & Hatina GV. 1977.Effect ofhexachlorobenzeneon reproduction in the rat. Arch Environ Contam Toxicol, 5: 207-2 16. Health Canada. 2009. Proposed Re-evaluation Decision for Quintozene. PRVD2009-02. 13 February 2009. Available online at:http://www.hc-sc.gc.calcps-spc/pest/part~consu1tations/qrvd2009-021quintozene-eng.php. Kanazawa, J. 1980. Prediction of biological concentration potential of pesticides in aquatic organisms. Rev. Plant Protec. Res. 13,27-36. Kanazawa, J. 1981a. Measurement of the Bioconcentration Factors of Pesticides by Freshwater Fish and Their Correlation with Physicochemical Properties or Acute Toxicities.Pestic.Sci. 12(4):417-424. Kanazawa, J. 1981 b. Bioconcentrationpotential of pesticidesby aquatic organisms. Japan pesticide information; 39, 12-16.

Page 54 of 70Kanazawa, J. 1983. A method of predicting the bioconcentration potential of pesticides using fish. JARQ, 17(3), 173-179. Kelly, B.C. and F.A.P.C. Gobas. 2003. An Arctic terrestrial food-chain bioaccumulation model for persistent organic pollutants. Environmental Science and Technology, 37(13): 2966-2974. Kelly, B.C.; Ikonomou, M.G.; Blair, J.D.; Morin, A.E. and F.A.P.C. Gobas. 2007. Food webspecific biomagnifications of persistent organic pollutants. Science 3 17:236-239. Korte, F., D. Freitag, H. Geyer, W. Klein, A.G. Kraus, and E. Lahaniatis. 1978. A Concept for Establishing Ecotoxicologic Priority Lists for Chemicals. Chemosphere7(1):79-102 McLeese, D.W., V. Zitko, and M.R. Peterson. 1979. Structure-Lethality Relationships for Phenols, Anilines and Other Aromatic Compounds in Shrimp and Clams. Chemosphere 8(2):53-57.ECOTOX reference#5810. Murray, F.J., Smith, F.A., Nitschke, K.D., Huniston, C.G, Kociba, R.J, and B.A. Schwetz. 1979. Three-generation reproduction study of rats given 2,3,7,8-tetrachlorodobenzo-p-diozin (TCDD) in the diet. Toxicol. Appl. Phannacol. 50:241-252. Niimi, A.J, Lee, H.B., and G.P. Kissoon. 1989. Octanollwaterpartition coefficients and biococnetration factors of chloronitrobenzenesin rainbow trout (Salmogairdneri). Environmental Toxicology and Chemistry; 8: 8 17-823. Oliver and Niimi. 1985. Bioconcentration factors of some halogenated organics for rainbow trout: limitations in their use for prediction of environmental residues. Environmental Science and Technology; 19, 842-849. Olsen, A.R., Snyder, B.D., Stahl, L.L. and J.L. Pitt. 2009. Survey design for lakes and reservoirs in the United States to assess contaminants in fish tissue. Environ Monit Assess, 150:91-100. Scheringer,M., MacLeod, M. and F. Wegmann. 2006. Analysis of four current POP candidates with the OECD Pov and LRTP screening Tool. Available online at: http://www.sustchem.ethz.clddocs/POP~Candidates~OECDDTool.pdf. Stahl, L.L., Snyder, B.D., Olsen, A.R., and J.L.Pitt. 2009. Contaminants in fish tissue fromUS lakes and reservoirs: a national probabilistic study. Environ Monit Assess, 150:3-19. Thompson, T.S., R.G. Treble, D.T. Waite, and A.J. Cessna. 1997. Bull. Environ.Contam. Toxicol. 58: 939-944. USEPA. 1992. National study of chemical residues in fish. United States Environmental Protection Agency. Office of Science and Technology. Volumes 1and 2. EPA 823-R-92-008 a and b. USEPA. 1995. Great Lakes Water Quailty Initiative criteria Documents for the Protection of Wildlife - DDT, Mercury, 2,3,7,8-TCDD, PCBs. U.S. Environmental Protection Agency, Office of Water. March 1995. EPA/820/B/951008. USEPA. 2004a. Overview of the Ecological Risk Assessment Process in the Office of Pesticide Programs. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, Washington DC. 100pp. January 23,2004. USEPA. 2004b. Exposure Analysis Modeling System (EXAMS): User manual and system documentation. United States Environmental Protection Agency. Revision G (May 2004). EPA1600m-00/081, USEPA. 2004c. Memorandum entitled: "Revised reregistraiton eligibility decision document (RED) of pentachloronitrobenzene (PCNB, PC Code 056502): Product and Residue Chemistry Considerations."U.S. Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Office ofPegticide Programs, Health Effects Division. July 2 1,2004.

Page 55 of 70USEPA. 2006. Reregistration Eligibility Decision for Pentachloronitrobenzene. U.S. Environmental Protection Agency, Office of Prevention, Pesticidesand Toxic Substances, Office of Pesticide Programs,Washington DC. USEPA.2008a. White paper on methods for assessing ecological risks ofpesticideswith persistent,bioaccumulative and toxic characteristics. Submitted to the FIFRA ScientificAdvisory Panel for review and comment. United States Environmental Protection Agency, Environmental Fate and Effects Division. Available online at: http://www.epa.gov/scipoly/sap/meetings/2008/october/sapgbt~whitepaper~final~Oct~7~08d.pdf. USEPA. 2008b. Framework for application of the toxicity equivalence methodology for polychlorinated dioxins, furans, and biphenyls in ecologicalrisk assessment.United States Environmental Protection Agency. Office of the Science Advisor,Risk Assessment Forum.EPA 1001R-081004.June 2008. USEPA. 2008c. EPI SuiteTM v4.0. United States Environmental Protection Agency. Available online at: http://www.epa.gov/oppt/exposure/pubs/episuite.htm. USEPA 2009. User's guide and technical documentation for KABAM version 1.0. United States Environmental ProtectionAgency. Office of PesticidePrograms. Environmental Fate and Effects Division.April 7, 2009.

van Birgelen,A. P. (1998). Hexachlorobenzene as a possiblemajor contributor to the dioxin activity ofhuman milk. Environ. Health Perspect. 106,683488.
Van den Berg, M., L. Birnbaum, A.T. Bosveld et al. 1998. Toxic equivalency factors (TEFs) for PCBs, PCDDs, PCDFs for humans and wildlife. Environ. Health Perspect. 106(12):775-792.
Van den Berg, M., L.S. Birnbaum, M. Denison et al. 2006. The 2005 World Health Organization re-evaluation of human and mammalian toxic equivalency factors for dioxins and dioxin-like compounds. Toxicol. Sci. 93(2):223- 241. Wagmann, F., M. Maclead, M. Scheringer. 2007. POP Candidates 2007. Model results on overall peirsistence and Long-range transport potential using the OECD Pov and LRTP Screening tool. Sweiss Federal Institute of Technology, ETH Zurich, Switzerland. httl3://www.sustchem. cthz.ch/dovvnloads/POPPCandidates~~O07~ETI 1Z.pdf. WHO. 1997. Hexachlorobenzene. Environmental Health Criteria 195. Geneva:World Health Organization. Available online at: http://www.inchem.org/documents/ehc/ehc/ehc195.htm.
DP Barcode D291276. "Environmental Fate and Ecological Risk Assessment for the Re-registration of Pentachloronitrobenzene." United States Environmental Protection Agency, Office of Pesticide Programs, Environmental Fate and Effects Division. Submitted StudiesIdentzjiedby MRlD number:
MRID 40580202. Forbis, A. (1988) Uptake, Depuration and Bioconcentration of Carbon 14-PCNB to Bluegill Sunfish (Lepomismacrochirus): Final Report No. 35965. Unpublished study prepared by AnalyticalBio-Chemistry Laboratories, Inc. 37 p. MRID 40618001. Grimes, J.; Jaber, M. (1988) PCNB: An Acute Oral Toxicity Study with the Bobwhite: Final Report: ProjectNo. 117-157. Unpublished study preparedby Wildlife International Ltd. 39p. MRID 4061 8004. Surprenant,D. (1988) Acute Toxicity of Pentachloronitrobenzene Technical to Bluegill (Lepomis macrochirus) Under Flow-through Conditions: Report No. 88-4-2697; Study No. 4 1.1 187.6108.105.Unpublished study prepared by Springborn Life Sciences, Inc. 37 p. MRID 40652602. Fletcher, D. (1988) Technical Grade PCNB: 9-day Acute Dietary LC50 Study in Bobwhite Quail: Rept. No. 88 QC 108.Unpublished study preparedby Bio-Life Associates, Ltd. 29 p.

Page 56 of 70MRID 40652603. Fletcher, D. (1988) Technical Grade PCNB: 9-day Acute Dietary LC50 Study in Mallard Ducklings: Rept. No. 88 DC 107. Unpublished study prepared by Bio-Life Associates, Ltd. 29 p. MRID 40832301. Suprenant, D. (1988) Acute Toxicity of Pentachloronitrobenzene Tec- hnical to Mysid Shrimp (Mysidopsis bahia) Under Flow-through Co- nditions: SLS Report #88-6-2748: SLS Study #41.1187.6109.515. Unpublished study prepared by Springborn Life Sciences, Inc. 38p. MRID 40865301. Bowman, B. (1988) Determination of the Hydrolysis Rate of ?Carbonl- PCNB: Project ID. 36821. Unpublished study prepared by Analyti- cal Bio-Chemistry Laboratories, Inc. 304p. MRID 40882902. Surprenant, D. (1988) Acute Toxicity of Pentachloronitobenzene (PCNB) to Eastern Oysters (Crassostrea virginica) Under Flow- through Conditions: Project ID: SLS Report No. 88-6-2760; SLS Study No. 11857.0488.6101.504. Unpublished study prepared by Springborn Life Sciences, Inc. 43 p. MRID 40882903. Surprenant, D. (1988) Acute Toxicity of Pentachloronitrobenzene to Sheepshead Minnow (Cyprinodon variegatus) Under Flow-through Conditions: Project ID: Report No. 88-7-2764; SLS Study No. 11857.0488.6100.505. Unpublished study prepared by Springborn Life Sciences, Inc. 39p. MRID 40972601. Bowman, B.; Fennessey, M. (1988) Determinationofthe Hydrolysis Rate of ?Carbon 141-PCNB: ABC Final Rept. #36005. Unpublished study preparedby Analytical Bio-Chemistry Laboratories, Inc. 50 p. MRID 40992701. Swigert, J. (1988) Acute Flow-through Toxicity of PCNB to Rainbow Trout (Salmo gairdneri): Final Report #36829. Unpublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 279 p. MRID 41004801. Carpenter, M.; Bowman, B. (1988) Photodegradation Study of ?carbon 141-PCNB on Soil Surface: ABC Final Report No. 36823. Unpu- blished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 313p. MRID 41178001. Bowman, B. (1989) Laboratory Volatility from Soil of PCNB: ABC Final Report #37090. Unpublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 311 p.
MRID 41200001. Burgess, D. (1989) Uptake, Depuration and Bioconcentration of Carbon 14-PCNB by Bluegill Sunfish (Lepomis rnacrochirus): Rept. # 36872. Unpublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 346p. MRID 41203602. Daly, D. (1989) Anaerobic Soil Metabolism of ?Carbon 

### - 141-Penta- chloronitrobenzene: Final Report No. 35905. Unpublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 49 p. MRID 41332801. Beavers, J.; Foster, J.; Lattin, A.; et al. (1989) Pentachloronitrobenzene (PCNB): A Onegeneration Reproduction Study with the Bobwhite (Colinus virginianus): Lab Project Number: 1171161. Unpublished study prepared by Wildlife International Ltd. 113p. MRID 41332802. Beavers, J.; Foster, J.; Lattin, A.; et al. (1989) Pentachloronitrobenzene (PCNB): A Onegeneration Reproduction Study with the Mallard (Anasplatyrhynchos): Lab Project Number: 1171162. Unpublished study prepared by Wildlife International Ltd. 115 p.
MRID 41384301. Cranor, W.; Patterson, C. (1989) Anaerobic Soil Metabolism of ?Car- bon 141- pentachloronitrobenzene: ABC Final Report #36825. Un- published study prepared by Analytical Bio-Chemistry Labora- tories, Inc. 759 p.
MRID 4 1384501. Cranor, W. (1 989) Aerobic Soil Metabolism of ?Carbon 141-penta- chloronitrobpzene: ABC Final Report # 36824. Unpublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 1088p.

Page 57 of 70MRID 41443101. Kuhn, J. (1989) Acute Oral Toxicity Study in Rats: Technical Grade PCNB 95%: Lab Study Number: 6085-89. Unpublished study prepared by Stillmeadow,Inc. 11p. MRID 41648201. Dykes, J. (1990) Soil Adsorption/Desorption with ?Carbon 141-PCNB: Lab Project Number: 38405. Unpublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 509 p. MRID 41686001. Cranor, W.; Patterson, C. (1990) Amended Final Report to: Anaerobic Soil Metabolism of ?carbon 141-Pentachloronitrobenzene, MRID 41- 384301: Lab Project Number: #36825. Unpublished study prepared by Analytical Bio-Chemistry Laboratories, Inc. 49 p. MRID 4 17 13201. Kabler, K. (1990) Photodegradation Study of ?C 141-PCNB on Soil Surface: Supplement to MRID 4 100480 1: Lab Project Number: 36823 1. Unpublished study prepared by Analytical Bio-Chemistry Labs, Inc. 129p. MRID 41713202. Cranor, W. (1 990) Aerobic Soil Metabolism of ?C 141-Pentachloro-nitrobenzene: Supplement to MRID 41384501: Lab Project Number: 368241. Unpublished study prepared by Analytical Bio-Chemistry Labs, Inc. 1 17 p. MRID 41795702. Feiler, W. (1991) PCNB: Physical And Chemical Characteristics: Unpublished study prepared by Amvac Chemical Co. 76 p. MRID 4 191870 1. Schardein, J. (1991) PCNB: Two-Generation Reproduction Study in Rats: Lab Project Number: 399-086. Unpublished study prepared by International Research and Development Corp. 633 p. MRID 41951701. Halls, T. (1991) Characterization of carbon 14 -PCNB Residues in Water and Bluegill (Lepomis macrochirus) Tissues: Lab Project Number: 37024. Unpublished study prepared by ABC Labs, Inc. 58 p. MRID 42094401. White, C. (1991) Reply to EPA Rejection of PCNB Anaerobic Soil Metabolism Study MRID #41203602. Unpublished study prepared by Uniroyal Chemical Co., Inc. 18p. MRID 42112801. Cady, C.; Cranor, W. (1991) Supplement to: Aerobic Soil Metabolism of Carbon 14- Pentachloronitrobenzene on Sandy Loam Soil: Lab Project Number: 368242. Unpublished study prepared by ABC Labo- ratories, Inc. 270 p. MRID 42112802. Cady, C.; Cranor, W. (1991) Supplement to: Anaerobic Soil Metabol- ism of Carbon 14- Pentachloronitrobenzene on Sandy Loam Soil: Lab Project Number: 368251. Unpublished study prep&ed by ABC Laboratories, Inc. 264p. MRID 42336201. Horree, D. (1992) Aqueous Photolysis of PCNB: Lab Project Number: 9127. Unpublished study prepared by Uniroyal Chemical Co., Inc. 5 1 p. MRID 4260620 1. Bashir, M. (1992) Aqueous Photolysis of (carbon 14)-Pentachloronitrobenzene:Lab Project Number: 368223. Unpublished study prepared by ABC Labs, Inc. 9 18 p.
MRID 42606202. Bashir, M. (1992) Aqueous Photolysis of (carbon 14)-Pentachloronitrobenzene:Lab Project Number: 368223A. Unpublished study prepared by ABC Labs, Inc. 105 p. MRID 4291 1902. Misra, B. (1993) Aerobic Soil Metabolism of Pentachloronitrobenzene (PCNB): Lab Project Number: ME 9100 131.Unpublished study prepared by Pittsburgh Environmental Research Lab., Inc. 89 p. MRID 43 179301. Vithala, R. (1 994) PCNB Metabolite Characterization in Fish and Water Samples from a FlowThrough Bluegill Bioconcentration Study: Review in Conjunction with MRID 40580202: Lab Project Number: 92 131:40366. Unpublished study prepared by ABC Labs., Inc. and Uniroyal Chemical Co., Inc. 131 p.

Page 58 of 70MRID 43751 101. Merricks,D.; Jensen, M. (1995)PCNB Field Volatility Study: Lab ProjectNumber: 1919: 9234: 92-109.Unpublished study preparedby AgrisearchInc. 143p.

Page 59 of 70Appendix A. Octanol-waterPartitioningCoefficients ofPCNB and its Degradates The predictions of the bioaccumulation portion of KABAM are most sensitive to the octanolwater partition coefficient (Kow) value selected to represent a chemical. Therefore the accuracy ofthis parameter influences the uncertainties and certainties associatedwith model predictions of concentrationsof PCNB in tissues of aquatic organismsresultingfrom bioaccumulation.
In a registrant-submitted study (MRID 41795702), the Kow of PCNB was calculated using the HPLC retention time correlationmethod. Followingthis method, retention times were calculated for 

### 6 reference chemicals with known Kow values (specifically: benzene, bromobenzene, biphenyl, bibenzyl, DDE and hexachlorobenzene). Note that several of the reference chemicals were organochlorines. A log linear relationship 

### (R~ = 0.98) was then derived where retention time was related to Kow. The log linear relationship was then used to translate the experimental retention time ofPCNB into an estimateofKow. Theresulting Log Kow ofPCNB was 5.0. The registrant-submitted Kow estimate for PCNB is consistent with literature values that were experimentally derived using the HPLC retention time correlation method (Log Kow range: 5.01- 5.30; Table Al). Note that the other studies using the HPLC retention time correlation method used different sets of reference chemicals to derive log linear relationships between retention time and Kow. The registrant-submitted value is also consistent with the EPISuite (USEPA 2008) estimate of 5.03, which was determined using the atomlfiagment contribution method. Several studies are available in the literature that report Kow values for PCNB that were calculated using the shake flask method. These values are lower than the registrant submitted Log KO, value of 5.0 (range: 4.22-4.77;Table Al). In general, the shake flask method is useful for chemicals with Log KO, values below 5, but becomes less accurate for chemicals with Log KO, values above 5 (USEPA 2003). Despite this, the Kow values calculated using the shake flaskmethod are still within an order ofmagnitude ofthe registrant submitted value.
Table Al.Available Kow data for PCNB.
I Kanazawa 198 1 I Shake flask 1 16.552 1 4.22 1

Source 

## I Gever et al. 1984 I I I 

### I Shake flask (OECD Guideline 107. 1981) 

### 1 43.652 

### 1 4.64 

## 1 I Niimi et al. 1989 I I I 

### I Shake flask WSEPA 60014-79-032) 

### 1 58.884 

### 1 4.77 

## 1

Method

I 

### - 

## - 

## 1 Kawamoto and Urano 1989 

### 1 HPLC retention time correlation I I 

### 1 151.000 

### 1 5.18 

## 1 Kow Log Kow

I

The mean of all of the experimentally derived Kow values provided in Table A1 (including the shake flask and HPLC retention time correlation methods) is 104,000, which is equivalent to a Log KO, of 5.0. 100,000 102,329 107.152 MRID 4 1795702 Nakamura et al. 2001 USEPA 2007
McDuffie 1981 Donovan and Pescatore 2002

Page 60 of70 5.00 5.01 5.03 HPLC retention time correlation (EPA TSCA guideline) HPLC retention time correlation QSAR (atomlfiament contribution method)
HPLC retention time correlation HPLC retention time correlation 162,181 199,526 5.21 5.30Based on the above information, a Log KO, of 5.0 was selected as a representative value for PCNB. Thisvalue is used in this assessment to estimatethe bioaccumulation potential of PCNB. Since this assessment is also relevant to PCNB's degradates, it is necessary to understand the partitioning of the residues. Log KO, values for PCNB's degradates were estimated using EPISuite (USEPA 2008) and are provided in Table A2. PCA, the major environmental degradate ofPCNB, has a lower estimated Log KO, value comparedto PCNB. This indicatesthat PCA would accumulate in aquatic organisms less than PCNB. However; PCTA, which has been identified as a major degradate in fish BCF studies, has a higher estimated Log KO,, indicating that PCTA may accumulate more in aquaticorganisms comparedto PCNB. Table A2. Estimated Log Kow values for PCNB and its degradates. Residue 

## I Abbreviation 

## I Estimated Log K~~~

# 1 I pentachloronitrobenzene 

## I PCNB' 

## I 5.0 

## I

pentachloroaniline pentachlorothioanisole ~entachlorobenzene

Estimated using EPISUITE v. 4.0 (USEPA 2008). pentachlorothioanisole sulfoxide pentachlorothioanisole sulfone

References Donovan, S.F.and M.C. Pescatore. 2002. Method formeasuring the logarithm of the octanol-water partition coefficient", J. Chromatogr. A 952,47-61. PCA' PCTA'

PCB

Geyer, H., G. Politzki, and D. Freitag. 1984. Prediction of Ecotoxicological Behaviour of Chemicals: Relationship Between N-OctanolIWater Partition Coefficient and Bioaccumulation of Organic Chemicals by Alga Chlorella. Chemosphere 13(2):269-284 4.3 5.8 5.2

'~dentified in fishtissue. PCTASO' PCTASOz

Kanazawa, J. 198 1 a. Measurement of the Bioconcentration Factors of Pesticides by Freshwater Fish and Their Correlation with Physicochemical Properties or Acute Toxicities. Pestic.Sci. 12(4):417-424. 3.7 3.8

Kawamoto, K. and K. Urano. 1989. Parameters for predicting fate of organochlorine pesticides in the environment. I. Octanolwater and air-water partition coefficients,Chemosphere 18(9-lo), 1987-1996. McDuffie, B. 1981.Estimation of octanollwater partition coefficients for organic pollutants using reverse-phase HPLC, Chemosphere 10(1),73-83.
MRID 4 1795702. Feiler, W. (1991)PCNB: Physical And Chemical Characteristics: Unpublished study prepared by Amvac Chemical Co. 76 p. Nakamura, M., Suzuki, T.Ammo, K. and S. Yamada. 2001. Relation of sorption behavior of agricultural chemicals in solid phase extraction with their octanol-water partition coefficients evaluated by HPLC, Anal. Chim. Acta 428(2), 219-226 (2001). Niimi, A.J, Lee, H.B., and G.P. Kissoon. 1989. Octanollwater partition coefficients and biococnetration factors of chloronitrobenzenes in rainbow trout (Salmo gairdneri). Environmental Toxicology and Chemistry; 8: 817-823.
USEPA. 2008. EPI SuiteTM v4.0. United States Environmental Protection Agency.

Page 61 of70Appendix B. Open literature review summariesfor bioconcentration studies involving 

### PCNB On 9/16/09, ECOTOX (htt~:/lcfpub.e~a.~ovlecotox/) was searched for aquatic "accumulation" studies relevant to PCNB. The following list of studies were returned by ECOTOX:

ECOTOX # Citation: 378 Freitag, D., H. Geyer, A. Kraus, R. Viswanathan,D. Kotzias, A. Attar, W. Klein, and F. Korte. 1982. Ecotoxicological Profile Analysis VII. Screening Chemicals for Their Environmental Behaviorby Comparative Evaluation.Ecotoxicol.Environ.Saf.6:60-81.
5113 Niimi, A.J, Lee, H.B., and G.P. Kissoon. 1989. Octanol/waterpartition coefficientsand biococnetration factors of chloronitrobenzenesin rainbow trout (Salmo gairdneri). Environmental Toxicology and Chemistry; 8: 817-823.
7079 Korte, F., D. Freitag, H. Geyer, W. Klein, A.G. Kraus, and E. Lahaniatis. 1978. A Concept for Establishing Ecotoxicologic Priority Lists for Chemicals. Chemosphere7(1):79-102.
9146 Schauerte,W., J.P. Lay, W. Klein, and F. Korte. 1982.Long-Tern Fate of Organochlorine Xenobiotics in Aquatic Ecosystems. Distribution, Residual Behavior, and Metabolism of Hexachlorobenzene.Ecotoxicol.Environ.Saf.6:560-569.
10750 Kanazawa,J. 1983. A method of predicting the bioconcentration potential of pesticides using fish. JARQ, 17(3), 173-179.
11297 Geyer, H., G. Politzki, and D. Freitag. 1984. Prediction ofEcotoxicological Behaviour of Chemicals: Relationship BetweenN-OctanoVWaterPartition Coefficientand Bioaccumulationof Organic Chemicalsby Alga Chlorella. Chemosphere 13(2):269-284
12534 Kanazawa, J. 1981b.Bioconcentration potential of pesticides by aquatic organisms. Japan pesticide information; 39, 12-16.
14353 Oliver, B.G., and A.J. Niimi. 1985. Bioconcentration Factors of Some Halogenated Organics for Rainbow Trout: Limitations in Their Use for Prediction of Environmental Residues. Environ.Sci.Techno1. 19(9):842-849. 15599 Kanazawa, J. 1981a.Measurement of the Bioconcentration Factors ofPesticidesby Freshwater Fish and Their Correlation with Physicochemical Properties or Acute Toxicities.Pestic.Sci. 12(4):417-424.
17318 Freitag, D., J.P. Lay, and F. Korte. 1984. Environmental Hazard Profile

### - Test Results as Related to Structures and Translation into the Environment. In: K.L.E.Kaiser (Ed.), QSAR in Environmental Toxicology,Proc.ofthe Workshop held at McMasterUniversity, Hamilton, Ont., Aug.16-18, 1983, D.Reide1Publ.Co., Dordrecht, Netherlands :1 11-131 59925 Kanazawa, J. 1980. Prediction of biological concentration potential of pesticides in aquatic organisms. Rev. Plant Protec. Res. 13,27-36.
The reviews of these studies are provided below

Page 62 of 70Open Literature Review Summary Chemical Name: pentachloronitrobenzene (PCNB) (CAS # 82-68-8) ECOTOX Record Numbers and Citations: ECOTOX # 3781. Freitag, D., H. Geyer, A. Kraus, R. Viswanathan, D. Kotzias, A. Attar, W. Klein, and F. Korte. 1982. Ecotoxicological Profile Analysis VII. Screening Chemicals for Their Environmental Behavior by Comparative Evaluation. Ecotoxicol.Environ.Saf. 6:60-81. ECOTOX # 11297. Geyer, H., G. Politzki, and D. Freitag. 1984. Prediction of Ecotoxicological Behaviour of Chemicals: Relationship Between N-OctanolIWater Partition Coefficient and Bioaccumulation of Organic Chemicals by Alga Chlorella. Chemosphere 13(2):269-284 ECOTOX # 17318. Freitag, D., J.P. Lay, and F. Korte. 1984. Environmental Hazard Profile - Test Results as Related to Structures and Translation into the Environment. In: K.L.E.Kaiser (Ed.), QSAR in Environmental Toxicology, Proc.of the Workshop held at McMaster University, Hamilton, Ont., Aug.16-18, 1983, D.Reide1 Publ.Co., Dordrecht, Netherlands :111-1 3 1 Purpose ofReview: RED follow up Date ofReview: September 16,2009 Summary of Study Findings: One of the purposes of this study was to develop Bioconcentration Factors (BCFs) for algae and for fish. All three ECOTOX references reported the results of a study where green algae (Chlorella fusca) were exposed to 50 yglL 14

C-labeled PCNB and maintained at room temperature (20-25°C). Algae were tested in 500 mL Erlenmeyer flasks, with glass stoppers. After a 24 hour exposure period, 14c residues in algae and in water were measured, with 67% in algae and 38% in water. The resulting BCF was 3,100 based on wet-weight (units: (pglg-ww)l(pglmL)).
In addition, Greitag et al. 1982 and 1984 reported results of a study involving the bioconcentration of PCNB in golden orfs (Leuciscus idus melanotus). In the study, 5 fish were exposed to 0.4 pglL 14c-labeledPCNB for 3 days at room temperature (20-25OC). Fish were approximately 1.5 g and were maintained in a 12.5 L flask containing 10 L of test solution. Fish were not fed during the exposure period and the test solutions were not aerated. The resulting BCF value was 1140 (Freitag et al. 1982and 1984) (units: (pglg-ww)l(pglmL)). Description of Use in Document: Qualitative Rationale for Use: For characterizationofbioaccumulation potential ofPCNB in aquatic ecosystems Limitations of Study: Potential degradation of PCNB in algae and in fish is not discussed in the articles, however; since 14c residues were measured, residues of PCNB are included in the reported BCF values. In addition, lipid compositions of the test organisms, which can affect bioconcentration results, were not reported by the study authors. Reviewer comments: 1) Comparison of study design and results reported in the 3 studies cited here indicates that these publications report the results (relevantto algae and fish) ofthe same study. 2) This study also included data for 34 other chemicals. Only information relevant to PCNB was reviewed. 3) This study included information where chemical degradation by activated sludge was examined. This part of the study was not reviewed. 4) This study included information where laboratory rats were dosed with PCNB and retention and elimination of PCNB was examined. This part of the study was not reviewed. 5)ECOTOX # 11297 also included results of an octanol-water partition coefficient (Kow) study conductedusing the shake flask method (according to OECD guideline 107, dated 1981). The resulting Log Kow was 4.64. Reviewer: Kristina Garber, Biologist, ERB4

Page 63 of 70Open Literature Review Summary Chemical Name: pentachloronitrobenzene (PCNB) (CAS # 82-68-8) ECOTOX Record Number and Citation: ECOTOX#7079. Korte, F., D. Freitag, H. Geyer, W. Klein, A.G. Kraus, and E. Lahaniatis. 1978. A Concept for Establishing Ecotoxicologic Priority Lists for Chemicals. Chemosphere 7(1):79-102. Purpose of Review: RED follow up Date ofReview: September 16,2009 Summary of Study Findings: One of the purposes ofthis study was to develop Bioconcentration Factors (BCFs) for algae and for fish. This article reported the results of a study where green algae (Chlorellafusca) were exposed to 49 pgL 14c-labeled PCNB and maintained at room temperature (20-25°C). Algae were tested in 250 mLround-bottom flasks, with glass stoppers. After a 24 hour exposure period, 14c residues in algae and in water were measured. Two BCFs were reported: 14,000 and 22,000based on dry-weight (units: (pg/g-dw)/(pg/mL)). Geyer et al. 1984(ECOTOX #11297) report that C. fusca is approximately 1 g dry weight to 5 g wet weight. Using this conversion, the BCF values reported in this study correspond to 2800 and 4400, respectively, on a wet-weight basis (units: (pglg-ww)/(pg/mL)). This article also reported results of a study involving the bioconcentration of PCNB in golden orfs (Leuciscus idus melanotus). In the study, 5 fish were exposed to 14c-labeledPCNB for 3 days at room temperature (23~t3'C).Fish weighed approximately 2-5 g and were maintained in a 12 L flask (capped) containing 10 L of test solution. Fish were not fed during the exposure period and the test solutions were not aerated. Three test concentrations were used: 33, 6 and 0.4 pgL. Toxicity was observed in the 33 and 6 pg/L levels and therefore, the BCF values from these exposure concentrations are not considered useful. The BCF value for the 0.4 pg/L exposure level was 1130 (units: (~g/g-ww)/(pg/mL)). Description of Use in Document: Qualitative Rationale for Use: For characterization ofbioaccumulation potential ofPCNB in aquatic ecosystems Limitations of Study: Potential degradation of PCNB in algae and in fish is not discussed in the article, however; since 14c residues were measured, residues of PCNB are included in the reported BCF values. In addition, lipid compositions of the test organisms, which can affect bioconcentration results, were not reported by the study authors. Reviewer comments: 1)The study design is similar to that ofECOTOX#s 3781,11297 and 17318. 2) This study also included data for 3 several other chemicals. Only information relevant to PCNB was reviewed. 3) This study included information where chemical degradation by activated sludge was examined. This part ofthe study was not reviewed. 4) This study included information where laboratory rats were dosed with PCNB and retention and elimination of PCNB was examined. This part ofthe study was not reviewed. Reviewer: Kristina Garber, Biologist, ERB4 Citation: ECOTOX # 11297. Geyer, H., G. Politzki, and D. Freitag. 1984. Prediction of Ecotoxicological Behaviour of Chemicals: Relationship Between N-OctanolIWater Partition Coefficient and Bioaccumulation of Organic Chemicals by Alga Chlorella. Chemosphere 13(2):269-284

Page 64 of 70Open Literature Review Summary Chemical Name: pentachloronitrobenzene (PCNB) (CAS # 82-68-8) (also called Qunintozene) ECOTOX Record Numbers and Citations: #59925. Kanazawa, J. 1980. Prediction of biological concentration potentialofpesticides in aquatic organisms. Rev. Plant Protec. Res. 13,27-36. #15599. Kanazawa, J. 1981a. Measurement of the Bioconcentration Factors of Pesticides by Freshwater Fish and Their Correlation with Physicochemical Propertiesor Acute Toxicities.Pestic.Sci. 12(4):417-424. # 12534. Kanazawa, J. 1981 b. Bioconcentration potential of pesticides by aquatic organisms. Japan pesticide information; 39, 12-16. #10750. Kanazawa, J. 1983. A method of predicting the bioconcentrationpotential of pesticides using fish. JARQ, 17(3), 173-179. Purpose ofReview: RED followup Date of Review: September 16,2009 Summary of Study Findings: One of the purposes ofthis study was to develop Bioconcentration Factors (BCFs)for fish. All four ECOTOX references reported the results of a bioconcentration study where wild-caughttopmouth gudgeon (Pseudorasborapawa) were exposedto PCNB. Fish weighing 2-5 g were caught from the Inari River (Japan) and acclimated for approximately 1 month prior to exposure. Fish were maintained in aerated 20 L tanks with flow through systems (300 mllmin) and maintained at a temperature of 20h2"C. Technical grade PCNB was added to purified water with acetone as a solvent.Fish (15-20) were exposed to 10-20 pglL PCNB for 14 d, then transferred to "clean" water for 30 d. Fish were fed once per day. PCNB concentrations were measured using gas chromatography.TheresultingBCF for PCNB was 238 based on wet-weight. Description ofUse in Document: Qualitative Rationale for Use: For characterizationofbioaccumulationpotential ofPCNB in aquaticecosystems Limitations of Study: Potential degradation of PCNB in fish is not discussed in the articles. Since residues of PCNB were not included as analytes, the reported BCF is likely an underestimateof the expected value relevant to total residues of concern. In addition, lipid compositions of the test organisms, which can affect bioconcentration results, were not reported by the study author. Reviewer comments: 1) Comparisonof study design and results reported in the 4 studies citedhere indicates that thesepublications report the results of the same study. 2) This study also included data for severalother chemicals.Only information relevant to PCNB was reviewed. 3) This study also included results of an octanol-waterpartition coefficient (Kow) study conductedusing the shake flask method. The resulting Kow was 16,552 (Log Kow =4.22). Reviewer: Kristina Garber,Biologist, ERB4

Page 65 of 70Open Literature Review Summary Chemical Name: pentachloronitrobenzene (PCNB) (CAS # 82-68-8) ECOTOX Record Numbers and Citations: #5113. Niimi, A.J, Lee, H.B., and G.P. Kissoon. 1989. Octanollwaterpartition coefficients and biococnetration factors of chloronitrobenzenes in rainbow trout (Salmo gairdneri). Environmental Toxicology and Chemistry; 8: 8 17-823. Purpose of Review: RED followup Date of Review: September 16,2009 Summary of Study Findings: One of the purposes of this studywas to develop Bioconcentration Factors (BCFs)for fish.
In a bioconcentration study, rainbow trout (Salmo gairdneri) were exposed to 0.69 pg/L PCNB, as well as 17 other chloronitrobenzenes for 36 days. Fish weighed 153(*29) g at test initiationand 178(%30) g at test completion. Mean lipid content of fish averaged 8.4(&1.4) mglg wet weight (equivalent to 0.84%).BCF values taken at 5, 12, 20, 28, and 36 day time periods ranged 114-261 (see Table below), with an overall mean of 171 (339). The authors ofthis study observed that fish concentrations of PCNB reached equilibrium within 5 days, but significant differences in BCF values were observed at different time periods. BCF values for PCNB at different days ofthe study.

Description of Use in Document: Qualitative Rationale for Use: For characterizationofbioaccumulationpotential ofPCNB in aquaticecosystems Mean BCF

Limitations of Study: This study design involved exposing fish to 18 chemicals. It is unknown whether or not the mixture of chemicals would influence the bioconcentrationofPCNB. Standard deviation

In addition, potential degradation of PCNB in fish is not discussedin the articles. Sinceresidues of PCNB were not included as analytes,the reported BCF is likely an underestimate of the expected value relevant to total residues of concern. Reviewer comments: 1) As noted above, this study also included data for several other chemicals. Only information relevant to PCNB was reviewed. 2) This study also included results of an octanol-water partition coefficient (Kow) study conductedusing the shake flask method. The resulting Log Kow was 4.77. Reviewer: Kristina Garber, Biologist,ERB4

Page 66 of70Open Literature Review Summary Chemical Name: pentachloronitrobenzene (PCNB) (CAS # 82-68-8) ECOTOX Record Numbers and Citations: ECOTOX #14353. Oliver, B.G., and A.J. Niirni. 1985. Bioconcentration Factors of Some Halogenated Organics for Rainbow Trout: Limitations in Their Use for Prediction of Environmental Residues. Environ.Sci.Techno1. 19(9):842-849. Purpose ofReview: RED follow up Date ofReview: September 17,2009 Summary of Study Findings:One ofthe purposes of this study was to develop Bioconcentration Factors (BCFs) for fish. In this bioconcentration study, rainbow trout (Salmogairdneri) were exposed for different time intervals (7,21, 35, 75 and 96 days) to a mixture of 18 chlorinated and brominated organic chemicals, including PCNB. Fish were exposed at either 1.4or 14 ngIL PCNB. Fish were maintained in "self-cleaning" tanks with a flow rate of 6LImin). The temperature was 15OC. At test initiation, 32 fish were placed in the tanks (1 per test concentration).At each time interval, 6 fish were removed and analyzed for chemical concentrations. BCF values relevant to each time step are provided in the table below.

Description ofUse in Document: Qualitative Rationale for Use: For characterization of bioaccumulation potential ofPCNB in aquatic ecosystems Limitations of Study: This study design involved exposing fish to 18 chemicals. It is unknown whether or not the mixture of chemicals would influence the bioconcentration of PCNB. In addition, potential degradation of PCNB in fish is not discussed in the articles. Since residues ofPCNB were not included as analytes, the reported BCF is likely an underestimate of the expected value relevant to total residues of concern. 50 75 96 Mean

Reviewer comments: 1) As noted above, this study also included data for several other chemicals. Only information relevant to PCNB was reviewed. 2) In the publication, the authors indicate that predicted bioconcentration of PCNB is greater than observed bioconcentration since the chemical is metabolized rapidlyby fish. 3) There is some confusion regarding the notation associated with the BCF values. The article indicates that all BCF values shouldbe x10". However, in Figure 1 of the article, the BCFs are displayed as lo3. Based onthe;properties of the chemicals tested, and other BCF values for PCNB, it appears that the notation is incorrect. Therefore, the results displayed in the table above are reflective of the reviewer's assumption that all BCF values given in the study report shouldbe lo3. ND =not detected SD = standard deviation *Reviewer calculated 0.65 (0.47) ND 0.95 (0.53) 0.59 (0.27)

Reviewer: Kristina Garber, Biologist,ERB4 202 (35) 258 (57) 3 12 (49)

237"

Page 67 of 70 0.35 (0.08) 0.09 (0.04) 0.41 (0.12) 0.26 (0.15) 6.9 (2.5) 6.9 (1.7) 7.3 (1.5)

6.7* 284 (54) 262 (63) 288 (57)

245* 8.0 (1.3) 6.7 (1.O) 8.0 (1.8)

7.2"Open Literature Review Summary Chemical Name: pentachloronitrobenzene (PCNB) (CAS # 82-68-8) ECOTOX Record Numbers and Citations: ECOTOX # 9146. Schauerte, W., J.P. Lay, W. Klein, and F. Korte. 1982. Long-Term Fate of Organochlorine Xenobiotics in Aquatic Ecosystems. Distribution, Residual Behavior, and Metabolism of Hexachlorobenzene. Ecotoxicol.Environ.Saf.6560-569. Purpose ofReview: RED follow up Date of Review: September21,2009 Summary of Study Findings:PCNB was applied to a small pond (2-3 m diameter, 0.85 m deep). Five applications of 50 pg/L (ppb) 14c PCNB were made during approximately 1 month. Residue concentrations of the 3 chemicals were measured in water, sediment, aquatic plants (Lemna minor, Ranunculus aquatilis) and animals (Notonecta glauca, Libella quadrimaculata) present in the ponds for up to 166 weeks after the application. The study authors observed that the PCNB concentration in the water column decreased by 50% by 1.8 days after the last application. They attributed this to adsorption to sediment and biota present in the pond. Measured concentrations of PCNB in aquatic organisms were provided in Figure 3 ofthe article (provided below). Based on this information, it appeared that PCNB residue concentrations in aquatic organisms and in sediment were above 1 mglkg (ppm) for several months after the last application of PCNB to the pond. PCNB was not detected (detection limit 0.002 mgtkg) in aquatic plants at 24 weeks after the last application.

I1 1 I



### 1 1977 1979 last application FIG.3. PCNB-derived residues in an experimentally polluted smail pond. A, ~otonecfa glauca; B, Libella quadrimaculata (larvae); C,Lemna minor;D, Ranunculus aqualiiis;and E, sediment. Description of Use in DocumentlLimitations of study: This value has limited use for the PCN~ aquatic bioaccumulation assessment because it does not provide measured values of PCNB residues in aquatic organisms in a tabular form. Values are only displayed in Figure 3. Because tabular concentrations of PCNB in aquatic organisms,the water column and the sediment were not provided, the reviewer could not calculate bioaccumulation factors. In addition, the study authors indicated that PCNB was converted to pentachloroaniline and pentachlorthioanisole at 30 weeks after application; however, the article did not provide reports assoc$atedwith the measured concentrations of these degradates. Reviewer: Kristina Garber, Biologist, ERE34
Page 68 of 70Appendix C. Use of fugacity approach to estimate pesticide concentrations in earthworms located on treated fields
In order to explore the potential exposures of mammals and birds to pesticides in the soil and earthworms on the treatment site, a simple fugacity approach can be employed to estimate concentrations of the pesticide of interest earthworms. Fugacity is most often regarded as the "escapingtendency" of a chemical from a particular phase. Fugacity 

### (F) has units of pressure, generally pascals (Pa), and can be related to phase concentrations. For any particular environmental phase (e.g., water, soil, air, or biota) there is a corresponding "fugacity capacity" with units of mol/m3-pa and is denoted by Z. The relationship between fugacity, fugacity capacity and chemical concentration (C) is defined by Equation 1. Equation 1. C =Z

## *F Fugacity capacities for a given chemical are calculated for the phases of interest as part of the exposure point estimation methodology (Mackay and Paterson 1981). The following calculations of fugacity capacities for soil (Zs) and earthworms (ZE) (Equations 2 and 3, respectively) require several chemical-specific parameters and assumptions of system temperature (25OC) and steady state equilibrium.Parameter values relevant to Equations 2 and 3 are defined in Table C 1.
Equation 2. 

### Zs = Kd 

## * PS H Equation 3. 

### Z, = 

### L*Kow H Fugacity capacities for a given chemical are calculated for the phases of interest as part of the exposurepoint concentration estimationmethodology. By definition, the ratio between 

### Z values of differentphases (compartments) equals thepartitioning coefficient (e.g., Equation 4).

Zoc tan ol Equation 4. - -

### Kow 'water In this approach, it is assumed that a pesticide partitions between the soil, the (pore) water and the air contained within the soil of the treatment site. It is assumed that earthworms dwelling within the soil are exposed to a pesticide via ingestion of contaminated soil. The concentration of a pesticide in earthworm tissues can be calculated according to Equation 5 (see Table Cl for parameter definitions).
Equation 5. C, = C,

## * -& 

# ES 

# I

Page 69 of 70

# I CE 

# 1 Chemical concentration in earthworm tissue 

## I Table C1. Summary of parameters relevant to earthworm fugacity model.



## I H 

## I Henry's Law constant 

## I m3-palm01 

## I Units Symbol

CE'
cs 

# I Kd 

# I Soil partitioning coefficient 

# I cm3/g Definition



## I Kow 

## I Octanol to water partition coefficient 

## I none 

## I Chemical concentration in earthworm tissue Chemical concentration in soil



## \ L 

## I Lipid fkaction of earthworm 

## I none 

## I g/kg mol/m3



## I MW 

## I molecular weight ofchemical 

## / glmol 

## I I ZF 

## I Fuaacity capacity ofpesticide in earthworms 

## I mol/m3-pa 

## I

zs 

# I Fugacity capacity of pesticide in soil 

# I mol/m3-pa

Equation 5 can be redefined using equations 

### 2 and 

### 3 as follows in Equation 

### 6. Equation 6 is used to calculate the concentrationof apesticide in earthworms inhabitingthe soil oftreatment sites.

PE PS

C, 

### *L*K,,

Equation 6. C, = Kd 

## * Ps
Cs is intended to be representativeofthe steady-stateconcentrations ofthe pesticide ofinterest in soil. This value is calculated using PRZM. Kd and Kow are chemical-specific parameters. Kd was chosen to be consistent with the value input into 

### PRZM (15.5 cm31g). ps is dependant upon the soil properties of the selected PRZM scenario used to derive Cs. A value of 1.65g/cm3was selectedto represent ps. 

### L is based on the lipid content of earthworms, which was assumed to be 0.01 (Cobb et al. 1995). The resulting CEvalue is in units of mol/m3. This value is converted to units of gikg using equation 7. The density of the earthworm (pE)is assumed to be 1000kg/m3 (equivalent to density of water). density ofearthworm Bulk density of soil

Equation 7. C; = C, 

# *m PE kg/m3 g/cm3

References Cobb, G.P., E.H. Hol, P.W. Allen, J.A Gagne, R.J. Kendall. 1995. Uptake, metabolism, and toxicity ofterbufos in the earthworm (Lumbricus terrestris) exposed to COUNTER-15G in artificial soils. Environ. Toxicol. Chem. 14(2):279-285. Mackay, D. and S. Paterson. I981. Calculating fugacity. Environ. Sci. Technol. 15: 1006-1014. USEPA. 2008. User's Guide: T-REX Version 1.4.1 (Terrestrial Residue Exposure model). United States Environmental Protection Agency. Environmental Fate and Effects Division.

Page 70 of70