### NO 2



### Cl

Cl

Cl Cl Cl 

# Environmental Fate and Ecological Risk Assessment for the Re-registration of Pentachloronitrobenzene

CAS Registry Number 82-68-8 PC Code 056502

Prepared by:

Cheryl Sutton, Ph.D., Environmental Scientist John E. Ravenscroft, Biologist Thomas M. Steeger, Ph.D., Senior Biologist R. David Jones, Ph.D., Senior Agronomist Kevin Costello, Risk Assessment Process Leader U. S. Environmental Protection Agency Office of Pesticide Programs Environmental Fate and Effects Division Environmental Risk Branch IV 1200 Pennsylvania Ave., NW Mail Code 7507C Washington, DC 20460 Reviewed by: Elizabeth Behl, Branch Chief2 EXECUTIVE SUMMARY
Pentachloronitrobenzene (PCNB) is a contact fungicide used on a broad range of crops as both a soil and seed treatment and foliar application. This screening-level assessment focused on five major uses, i.e., turf, peanuts, cole crops, potatoes and cotton which account for over 86% of PCNB uses nationally. Turf and cotton combined account for 76% of the total pounds of active ingredient applied domestically, with potatoes accounting for an additional 9.9%. The three agricultural crops with the highest percentage of their total U.S. planted acres treated with PCNB are brussels sprouts (a cole crop), cotton and potatoes. The five agricultural or recreational (turf) uses of PCNB chosen to represent the use of the compound in the environment are turf, peanuts, cabbage (cole crop), potatoes and cotton. To simulate these uses, OPP used a standard Pennsylvania turf scenario, a standard North Carolina peanuts scenario, a standard Florida cabbage scenario, a standard Idaho potatoes scenario, and a standard Mississippi cotton scenario. Although there is a higher (1/3 greater) maximum rate for turf than the one modeled, it is an allowed usage only in California, Washington, and Oregon.
PCNB is a persistent, moderately volatile chemical that is not likely to be very mobile in most soils given the chemical’s tendency to sorb to organic matter. However, on sandy soils low in organic matter, PCNB may leach to groundw ater. PCNB can also move to surface waters in runoff and through spray drift (particularly for foliar applications such as to turf). Consistent with other chlorinated benzenes with moderate to high volatility, PCNB can also move to areas distant from use sites via long-range atmospheric transport. Once in the atmosphere, PCNB is not expected to degrade by photooxidation.
PCNB and its degradates (pentachloroaniline, pentachlorothioanisole, pentachlorothioanisole sulfoxide, pentachlorothioanisole sulfone, pentachlorophenol and pentachlorobenzene) are likely to be persistent. The primary route of degradation for PCNB is through aqueous photolysis, the ideal conditions for this route of degradation (clear, shallow water) are limited under natural conditions as runoff water tends to be turbid and incident light in surface water bodies is attenuated with increasing depth of water. Although two guideline studies indicated that pentachlorophenol (PCP) is a degradate of PCNB, the exact conditions that favor the formation of this compound in soil or aquatic systems are uncertain. Although PCP is routinely detected in water/sediment monitoring studies, the compound PCP is also used as a wood preservative. Based on available information (including open literature data) it is deemed unlikely that the degradation of PCNB will result in levels of PCP in the environment that should be cause for concern relative to the environmental load already present from direct use of PCP.
Tier II (PRZM/EXAMS) models indicate that desp ite the volatility of PCNB and limited m obility in most soils, current maximum label application rates for one use (turf, other than on golf courses) could result in estimated surface water concentrations that reach the solubility limit (440 μg/L at 25 o C) of PCNB in water; the next highest estimated acute concentration (195 ppb) was less than half that value. While high application rates coupled with the persistence of PCNB yielded refined PRZM/EXAMS model estimates of acute drinking water concentrations at the solubility limit of PCNB

, chronic values are estimated to be an order of magnitude lower (66 μg/L). However, the currently used version of the PRZM/EXAMS model is unable to correctly account for volatility; thus, both acute and chronic es timated concentrations are likely overestimated, particularly for uses involving foliar application, such as on turf, where volatiliza tion may be a significant route of dissipation for the parent and the degradate PCA. Based on modeling results from a provisional version of PRZM/EXAMS (PRZM9; dated November 10, 2004), for which a QA/QC has not yet been completed by EFED, the estimated acute surface water concentrations from turf use are predicted to decrease by approximately 25- 27% (for drinking water and ecological exposure) when volatilization is accounted for. However, because the solubility limit of 440 ppb is used for the estimated drinking water concentration (in lieu of the previous model output value of 586.4 ppb), the effective decrease from taking volatilization into account is only 1.9%3 for acute exposure. Chronic drinking water exposures for turf use are predicted to decrease by approximately 34%, while chronic ecological exposures for turf use (21- and 60-day values) are predicted to decrease by approximately 22% and 28%, respectively, when volatilization is accounted for. For groundwater-derived drinking water, estimated concentrations of 31 μg/L were determined using the screening-level model SCIGROW based on PCNB use on bulbs where the application rate was the highest annual and highest single application rate of any of the labels evaluated.
PCNB has been detected in a limited number of surface water monitoring studies; however, the monitoring studies were either not targeted to PCNB application sites and times, or insufficient information was provided to allow for a complete evaluation of the data.
Estimated environmental concentrations for aquatic exposure assessments attempted to account for total residues (parent plus degradates/contaminants) of PCNB and included pentachloroaniline, pentachlorothioanisole, pentachlorobenzene, pentachlorophenol, pentachlorothioanisole sulfoxide, pentachlorothioanisole sulfone and hexachlorobenzene, inclusive of volatiles. PCNB is highly toxic to freshwater fish and invertebrates and is very highly toxic to estuarine/marine fish and invertebrates on an acute exposure basis. As indicated earlier, exposure to aquatic animals is likely and acute risk levels of concern are exceeded. Chronic risk levels of concern were also exceeded for freshwater fish and invertebrates; chronic effects include reduced number of eggs produced and reductions in the number of young surviving. Again, it is uncertain whether these chronic effects are indicative of PCNB’s ability to act on endocrine-mediated processes. The likelihood of chronic risk to estuarine/marine animals is uncertain since no data are available with which to assess the chronic toxicity of PCNB to estuarine/marine animals. However, based on acute to chronic ratios derived from freshwater studies, estimated NOEC’s for estuarine/marine invertebrates suggest that chronic risk is possible from the uses of PCNB modeled in this assessment.
No data were available on the effects of PCNB on either aquatic or terrestrial plants; therefore, it is not possible to assess the risks to plants associated with the current uses of PCNB. However, the single incident reported for PCNB affected terrestrial plants. Open literature suggests that, like aquatic animals, aquatic plants are able to accumulate PCNB residues and serve as a route of entry for PCNB into the aquatic food chain, although compounds such as PCNB and PCA are associated with relatively low dietary absorption efficiency and short metabolic half-lives. However, the likely persistence and toxicity of PCNB and its degradates coupled with the chemicals’ propensities to bioconcentrate, are concerns that underscore the potential vulnerability of aquatic communities to PCNB exposure resulting from labeled uses of the fungicide.
Given the persistence of PCNB and its degradates in the aquatic environment and the propensity of the compounds to bioconcentrate with bioconcentration factors as high as 22,000X, its presence in the benthic sediments is expected to serve as a likely route of exposure to benthic fauna and serve as a means of entry into aquatic food chains where the compound and/or its degradates may biomagnify as well. The data indicate that residues of PCNB and its degradates have been detected in aquatic plants and invertebrates; PCNB residues have also been detected in bottom-feeding fish at concentrations as high as 16 μg/kg.
Chronic and acute exposure from multiple applications of PCNB were estimated using a 35-day foliar half-life, a default value used for terrestrial assessments in the absence of data. This value is expected to result in overestimates of exposure of PCNB. At this time, no total foliar residue data for PCNB have been evaluated to determine their utility for dissipation rate determination. Although screening-level models indicate that terrestrial exposure to PCNB is likely through consumption of treated seed and foliar residues, the likelihood of acute mortality (risk) to either birds or mammals, based on a deterministic (risk quotient) approach, is low given that PCNB is practically nontoxic to both birds and mammals on an acute exposure basis. However, chronic risk levels of concern are exceeded for birds and mammals following consumption of PCNB-treated4 seed and PCNB residues on forage items. Chronic effects such as reductions in the number of eggs laid, number of viable embryos and numbers of 14-day survivors may result from chronic exposure of birds to PCNB. Although chronic exposure to PCNB did not result in reproductive effects in mammals, toxic effects on the liver and thyroid were noted. However, the relevancy of the mammalian chronic toxicity measurement endpoints to ecological assessment endpoints, i.e., survival, growth and reproduction, is uncertain. Chronic reproductive effects observed in birds and the thyroidal effects in mammals may be indicative of PCNB’s capacity to impact endocrine-mediated processes; literature data indicate that PCNB and two of its degradates (PCTA and PCP) have estrogen-binding abilities.
Although OPP does not typically estimate risks to terrestrial invertebrates, available data suggest that PCNB is practically nontoxic to bees. The honeybee contact LD 50exceeded the highest concentration tested, i.e., 100 μg/bee.
Major uncertainties associated with this assessment include the degree to which volatilization will impact exposure, the potential effects of PCNB on plants (terrestrial and aquatic), the chronic toxicity of PCNB to estuarine/marine animals, the endocrine disrupting potential of the compound, and potential effects of PCNB degradates along with the HCB contaminant. Although both terrestrial and aquatic risks have been identified for nontarget animals, OPP believes the predominate risk is associated with aquatic animals based on the likely presence of the PCNB and its degradates in sediments and the water column coupled with the ability of aquatic plants and animals to bioconcentrate these compounds.5 Acknowledgment
The Environmental Fate and Effects Division would like to thank Syracuse Research Corporation (Mario Citra, Antonio Quiñones-Rivera, Molly Ram sey, Gary Diamond, Sarah Rosenberg, Liz Gabriel and Philip Goodrum) and Syracuse Environmental Research Associates, Inc., for their efforts in conducting extensive literature searches on PCNB and its degradat es. We would also like to thank Syracuse Research Corporation (Philip Goodrum, Antonio Quiñones-Rivera , Molly Ramsey, Mario Citra, Janet Burris and Gary Diamond) for constructing a problem formulation for c onducting a more refined aquatic risk assessment. The contributions made by these individuals improved O PP’s understanding of relevant open literature and how the available literature might be used in probabilistic risk assessment context. Additionally, OPP would like to thank Chris Russom and Patricia Schmieder withEPA’s Office of Research and Development National Health and Environmental Research Laboratory Mid- Continent Ecology Division (MED) for improving our understanding of how extended literature searches compared with information contained within EPA’s on-line ECOTOX database and for their efforts in providing ecot oxicity profiles for PCNB and its degradates using the ASTER (Assessment Tools for the Evaluation of Risk) model. Finally, the EFED PCNB team would like to thank Michele Mahoney (formerly of EFED) for her efforts in interfacing between MED and OPP on the extended literature searches for PCNB.6 TABLE OF CONTENTS

EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

PROBLEM FORMULATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Mode of Action . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Use Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Major Crops Treated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Geographic Regions of Major Use Sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Historical Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

ENVIRONMENTAL FATE AND TRANSPORT CHARACTERIZATION . . . . . . . . . . . . . . . . . . . . . 16 Monitoring Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Soil and Sediment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

WATER RESOURCES ASSESSMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Surface Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Drinking Water EDWC’s (Surface Water) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Drench Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Refinement of Estimated Surface Water Concentrations for Golf Course Turf Use . . . 29 Groundwater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Pentachlorophenol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Monitoring Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
AQUATIC EXPOSURE ASSESSMENT (TIER II) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 EEC’s for Ecological Risk Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Seed treatment applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Avian Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Mammalian Exposure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Foliar Applications and Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

ECOLOGICAL EFFECTS CHARACTERIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Plant Toxicity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

RISK CHARACTERIZATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Risk Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Nontarget Terrestrial Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 Nontarget Aquatic Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Birds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56 Risk Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Refined Conceptual Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Endocrine Disruption Potential . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 Uncertainties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 Endangered Species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 637 LITERATURE CITED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

APPENDIX A1. USE CLOSURE MEMO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Registrants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Application Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 Application Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Use Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 Responses to specific questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

APPENDIX A2. ADDENDUM TO USE CLOSURE MEMO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 Application Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Use Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92 Responses to Specific Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
APPENDIX A3. QUANTITATIVE USAGE ANALYSIS FOR PCNB . . . . . . . . . . . . . . . . . . . . . . . . 99

APPENDIX B. ENVIRONMENTAL FATE DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Abiotic Degradation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Hydrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Aqueous Photolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Soil Photolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104 Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 Aerobic Soil Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 Anaerobic Soil Metabolism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106 Mobility and Persistence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Adsorption/Desorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Laboratory Volatility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 Field Volatility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109 Terrestrial Field Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 Bioaccumulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115 Bioaccumulation in Fish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

APPENDIX C. STRUCTURES FOR PCNB AND ITS MAIN FATE DEGRADATES . . . . . . . . . . . 116
APPENDIX D1. DRINKING WATER ASSESSMENT (TIER I) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Estimated Drinking Water Concentrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 Preliminary EDWC’s for a Soil Drench Use Scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Monitoring Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 Pentachlorophenol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126 Literature Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Attachment 1: FIRST File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 Attachment 2: SCI-GROW File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 Attachment 3: General fate and physical-che mical property source data for PCNB modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
APPENDIX D2. DRINKING WATER ASSESSMENT (TIER II) . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 Attachment 1. PRZM/EXAMS Outputs for the Drinking Water Assessment . . . . . . . . . . . . . 1378 Turf (Standard Pennsylvania Turf Scenario) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 Peanuts (Standard North Carolina Peanuts Scenario . . . . . . . . . . . . . . . . . . . . . . . . . . 139 Cabbage (Standard Florida Cabbage Scenario . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141 Potatoes (Standard Idaho Potatoes Scenario) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Cotton (Standard Mississippi Cotton Scenario) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
APPENDIX D3. INITIAL (TIER 1) SCREENING-LEVEL DRINKING WATER ASSESSMENT OF 11/12/03 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Attachment 1: FIRST File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 Attachment 2: SCI-GROW File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 Attachment 3: General fate and physical-che mical property source data for PCNB modeling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

APPENDIX D4. DRINKING WATER ASSESSMENT OF HCB AND PCB . . . . . . . . . . . . . . . . . . 160

APPENDIX D5 PRZM/EXAMS OUTPUTS FOR ECOLOGICAL RISK ASSESSMENT . . . . . . . . 177 Cabbage (Standard FL Cabbage Scenario) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 surface water numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177 benthic numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178 Cotton (Standard Mississippi Cotton Scenario) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 surface water numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 benthic numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183 Peanuts (Standard North Carolina Peanuts Scenario) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 surface water numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 benthic numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 Potatoes (Standard Idaho Potatoes Scenario) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 surface water numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 benthic numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 Turfgrass (Standard Pennsylvania Turfgrass Scenario) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 surface water numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 benthic numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195

APPENDIX D7. SCI-GROW MODELING OUTPUTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 Turf (two applications at 32.67 lb a.i./A/application) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 Peanuts (two applications at 10.0 lb a.i./A/application) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 Cole Crops (one application at 30.0 lb a.i./A/application) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209 Potatoes (one application at 25.0 lb a.i./A/application) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 Bulb Crops (one application at 213.4 lb a.i./A/application) . . . . . . . . . . . . . . . . . . . . . . . . . . . 210 Beans – dry type (one application at 40.84 lb a.i./A/application) . . . . . . . . . . . . . . . . . . . . . . . 210

APPENDIX E. ECOLOGICAL EFFECTS ASSESSMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 Toxicity to Terrestrial Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 Acute and Subacute Toxicity to Birds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 Chronic Toxicity to Birds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212 Acute and Chronic Toxicity to Mammals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214 Toxicity to Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 Toxicity to Freshwater Aquatic Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 Freshwater Fish, Acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215 Freshwater Fish, Chronic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2179 Freshwater Invertebrates, Acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 Freshwater Invertebrate, Chronic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218 Toxicity to Estuarine and Marine Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 Estuarine/Marine Fish, Acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 Estuarine and Marine Fish, Chronic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 Estuarine and Marine Invertebrates, Acute . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 Estuarine and Marine Invertebrate, Chronic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221

APPENDIX F. SPREADSHEET-BASED TERRESTRIAL EXPOSURE VALUES . . . . . . . . . . . . . 222
APPENDIX G. TERRESTRIAL EXPOSURE MODEL (ELL FATE Version 1.4a) OUTPUT . . . . . 223 Cabbage Maximum Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 Cabbage Mean Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224 Peanuts SLN (TX) Maximum Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 Peanuts SLN (TX) Mean Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226 Peanuts SLN (TX) #2 Maximum Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 Peanuts SLN (TX) #2 Mean Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228 Peanuts Maximum Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229 Peanuts Mean Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230 Potato Maximum Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231 Potato Mean Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 Turf Maximum Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233 Turf Mean Residues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234

APPENDIX H: ECOLOGICAL RISK ASSESSMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 Exposure and Risk to Nontarget Terrestrial Animals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23610 PROBLEM FORMULATION
In general, the analysis plan and rationale for completing this assessment, i.e. , the problem formulation, have been to determine whether current label uses of PCNB provide a means of exposure that could potentially represent an unreasonable likeli hood of adverse effects (risk) to nontarget endangered/threatened and nonendangered animals and plants that coul d potentially impact the reregistration eligibility decision under the Federal Insecticide, Fungici de and Rodenticide Act, the Food Quality Protection Act, and the Endangered Species Act. Over the cour se of its assessment, OPP has attempted to refine its problem formulation for PCNB by integrating both registrant-submitted guideline data and information collected from open literature to characterize the envir onmental fate and ecological effects of PCNB and its degradates. Because of over 1,700 use-pattern combin ations reported in EPA’s Label Use Information System (LUIS) database, and difficulties associated with sometimes poorly defined usage information, EFED extended extensive efforts to accurately characterize all of the labeled uses. However, based on information provided by the Biological and Economics Analysis Di vision (BEAD) and gleaned from internet-available sources such as the U. S. Geological Survey and the National Center for Food and Agricultural Policy’s (NCFAP) National Pesticide Use database, OPP iden tified several major crops based on pounds of PCNB used (turf, peanuts, cabbage [cole crop], pot atoes and cotton) on which to base its assessment.

The risk assessment considers formulations used fo r soil and foliar treatments, including granular, as well as seed treatments. Not all routes of exposure are considered, though. This ecological risk assessment does not take into account atmospheric transport in estimating environmental c oncentrations, nor does it account for ingestion of PCNB residues by animals in drinking water or contaminated grit, ingestion through preening activities, or uptake through inhalation or dermal absorption by terrestrial animals. Exposure to terrestrial animals is based primarily on dietary cons umption of foliar residues and treated seeds while aquatic assessments assume that all potential routes of direct exposure are accounted for. While PCNB is used in greenhouses and drench applications, these uses are typically conducted indoors and, thus, exposure to nontarget animals is limited. However, plants under going drench application indoors, or started indoors in treated soil mixtures, may eventually be transplanted outside along with the PCNB treated potting soil. This route of potential exposure, however, is not accountedfor in this assessment. Additionally, although a food web study suggests pentachloroaniline bioaccumulates, neither terrestrial nor aquatic assessments account for secondary exposure.
Maximum application rates on vulnerable soils for representative crops are selected for modeling environmental concentrations for this screening- level deterministic (risk quotient-based) assessment. Although there is a higher (1/3 greater) maximum rate fo r turf than the one modeled, it is an allowed usage only in CA, WA, and OR. This assessment is not inte nded to represent a site or time-specific analysis, i.e. assessments are intended to represent a national-level e xposure based on vulnerable soils as opposed to being a regionally specific exposur e assessment. Likewise, the most sens itive toxicity endpoints are used from surrogate test species to estimate treatment-related direct effects on acute mortality and chronic reproductive, growth and survival assessment endpoints. Toxicity tests are intended to determine pesticidal effects on birds, mammals, fish, terrestrial and aquatic invertebrates and plants. These tests include short-term acute, subacute and reproduction studies and are typically arranged in a hierarchical or tiered system which progresses form basic laboratory tests to applied field studies. The studi es are used to evaluate the potential of a pesticide to cause adverse effects, to determine whether further t esting is required, and to determine the need for precautionary label statements to minimize the potential adverse effects to nontarget animals and plants (CFR 40 §158.202, 2002).11 Surface water and groundwater-derived drinking wa ter estimates are provided for PCNB plus a degradate of concern, pentachloroaniline (PCA), and are used in human health risk assessments conducted by the Health Effects Division. Estimated environmen tal concentrations used in terrestrial ecological risk assessment are based on PCNB alone for terrestrial animal s. For aquatic ecological risk assessment, estimated environmental concentrations are based on total residues of PCNB, i.e. , parent plus its degradates identified in submitted guideline environmental fate studies (incl uding volatiles) and assumed to be of equal toxicity to the parent. No plant toxicity data were availabl e for PCNB; thus, the ecological risk to plants cannot be evaluated.
This screening-level assessment is not intended to pr ovide a site-specific understanding of particular PCNB uses and their effects on specific sp ecies. However, some refinements, e.g. Tier II aquatic exposure assessments, have been incorporated in to this assessment. Additionally, wh ere uncertainties exist, they have been identified along with possible avenues to address th e uncertainties in terms of additional data. Because the majority of PCNB use on turf is on golf course tu rf, which is the overall major use for PCNB, estimated surface water concentrations for both the drinking wa ter and ecological exposure assessments were adjusted to account for pesticide use on less than the total tu rf acreage. However, the values used in the risk assessment for turf use are based on non-ad justed EEC’s, as there are labeled turf uses other than golf course turf. The adjusted values for golf c ourse turf use are reported in a separate section of the chapter, rather than being incorporated throughout.
As part of its analysis plan, OPP worked with Office of Research and Development (ORD) National Health and Environmental Research Laboratory Mid- Continent Ecology Division to reduce uncertainty regarding the potential effects of PCNB and its degrad ates by using toxicity data captured in the on-line ECOTOX database. Additional toxicity estimates were provided for PCNB and its degradates using the ASTER (Assessment Tools for the Evaluation of Risk) model. OPP did not rely on the ASTER model outputs in its assessment of ecological risk to animals si nce sufficient data were available through registrantsubmitted and open literature to conduct a screening-level assessment; however, should a more refined assessment be required, the model outputs are available. Although ASTER did not estimate the toxicity of PCNB to aquatic plants, it was useful in providing aqua tic plant toxicity estimates for a number of chlorinated benzenes.
The conceptual model used to depict the ecologi cal risk associated with PCNB was initially fairly generic and assumed that as a pesticide, PCNB was cap able of affecting terrestrial and aquatic animals provided environmental concentrations were sufficien tly elevated as a result of labeled uses. However, through an iterative process of examining fate and eff ects data, the conceptual model has been refined to reflect the exposure pathways and the organisms for wh ich risk is most likely. Based on OPP’s screeninglevel assessment, the refined conceptual model for depi cting the risks of PCNB to nontarget animals is one that primarily focuses on birds and the aquatic envi ronment where exposure results from a combination of direct spray-drift and runoff of sediment-bound residues. Given the propensity for PCNB to sorb to sediments, acute mortality and chronic reproductive/grow th effects in aquatic animals may occur following exposure to PCNB and its major degradates suspended in the water column and/or in benthic sediments Although chronic risks to terrestrial animals may take place, there is uncertainty regarding the ecological relevancy of the measurement endpoints used to assess ch ronic effects in mammals. Thus the predominate concern for terrestrial animals focu ses on chronic risks to birds.
In the following sections, the use, environmental fate, and ecological effects of PCNB are characterized and, using a risk quotient (ratio of expos ure concentration to effects concentration) approach, risks to nontarget terrestrial and aquatic animals are estimated. Although risk, in the context intended here, is often defined as the likelihood and magnitude of adverse ecological effects, the risk quotient-based12 approach does not provide a quantitative estimate of like lihood and/or magnitude of an adverse effect. Such estimates may be possible through a more refined, probabilistic assessment; however, it is beyond the scope of this screening-level assessment.

INTRODUCTION
Pentachloronitrobenzene (PCNB; PC Code 056502) is a br oad-spectrum, contact fungicide belonging to the organochlorine (polychlorinated aromatic) class of chemicals. It is used to control various diseases caused by Rhizoctonia solani , as well as other fungal pathogens ( e.g ., Botrytis spp., Rhizopus spp., Aspergillus spp., Pellicularia spp., Fusarium spp. ). PCNB is reportedly used as the key chemical in controlling karnal bunt (caused by Tilletia caries ) in wheat. The compound is registered for use in controlling fungal diseases on a variety of food/feed and non-food crops, either as a seed treatment or soil/foliar treatment, and is currently undergoing a re-registration eligibility assessment. Seed treatment uses (with predominant uses in bold) on food/feed crops include: barley, beans, corn , cotton , garlic cloves, oats, peanut , peas, rice, safflower, sorghum, soybean , sugar beet, and wheat . Soil treatment uses (with predominant uses in bold) on food/feed crops include: beans (dry, succulent, snap ), cole crops ( broccoli , chinese broccoli, brussels sprouts, cabbage , chinese cabbage, cauliflower , collards, kale, mustard greens), cotton , garlic, hot pepper, peanut , pepper , potato, and tomato . Soil treatment uses (with predominant uses on bold) on non-food crops include: ornamental plants (b edding, bulb soak, cut flowers, flowering, foliage, trees, tropical foliage, woody), ornamental lawns and turf (grasses and dichondra), turf ( golf courses , home lawns, institutional areas, sod farms), and mushroom farms (outdoor areas). Formulation types for end use products include granular, liquid, emulsifiable concen trate, flowable, wettable powder, water soluble pouch and dust. PCNB is commonly used in combination with other insecticides and fungicides ( e.g ., carbaryl, imazalil, triadimenol, fuberidazole), partic ularly for soil applications to cotton ( e.g ., with etridiazole, disulfoton, and phorate), turf, potato, and peanuts ( e.g. , with ethoprop); and for seed treatment applications ( e.g. , with captan, carboxin, metalaxyl, TBZ, and Bacillus subtilis ). More specific information on the uses, formulations, and application rates of the compound can be located in the Use Characterization section (below) and in the Use Closure memo in APPENDIX A1, its addendum in APPENDIX A2 and the quantitative use analysis in APPENDIX A3

.
Mode of Action
The chemical’s mode of action is the inhibition of hyphal growth by means of the competitive inhibition of inositol. PCNB is used to control (p reventative and residual) against soil-borne diseases prior to infection of the plants. To date, resistan ce to PCNB has reportedly not been observed.

Use Characterization
PCNB is a contact fungicide that provides prev entative and residual protection against soil-borne diseases. Based on the current labels, it will be applie d in the environment either as a seed treatment or to soil. Applications to soil will be mainly as a ground spra y or as a granular formulation, with the potential for some foliar interception for applications that are post- emergent; some foliar applications will also occur based on information provided by the Registrants ( APPENDIX A1 : Use Closure Memo for PCNB Reregistration of 1/23/03; amendment 6/23/03 APPENDIX A2 ). While aerial application and chemigation are labeled methods for peanuts, the registrants indicated (AM VAC PCNB Smart Meeting, July18, 2001) that neither application method is an important one for that crop. Application methods that are used in the field (based on documents provided to OPP by the Registrants fo r the 7/18/2001 SMART Meeting) include broadcast or row drench, pre-emergent broadcast, row spray, in-fu rrow (spray and granular), furrow, foliar spray, band,13 transplant solution, and chemigation. Applications of PCNB are typically made only once a season, although the labels allow for repeat applications for some uses, such as turf. PCNB may be applied as a seed treatment, a pre-emergent, at planting or transplant, or as a post-emergent (either at mid-season for beans, peanuts, potatoes or ornamentals; or at the first appearance of disease on turf).
Major Crops Treated
Crops associated with the predominant uses of PCNB, as reported by the Registrants, were shown previously (in bold) in the Introduction section. The Registrants reported that the predominant uses are cotton, peanuts, turf, potatoes and seed treatment, and that the four crops most commonly (commercially) treated with PCNB as a seed treatment ar e cotton, peanut, soybean and wheat.

Based on information obtained from the National Ce nter for Food and Agricultural Policy (NCFAP; www.ncfap.org/database/default.htm ; accessed January 2004), among agricultural crops, PCNB is used most frequently on cotton, followed by peanuts. In the benchmark year 1997 (based on crop acreage in 1997 and pesticide use patterns for the year s 1995–1998), applications to cotton and peanuts accounted for more than 96% of the national use of PCNB on agricultural crops , with approximately 746,000 lbs of active ingredient applied to over 1 million acres of cotton and approxi mately 31,000 lbs applied to approximately 6000 acres of peanuts (NCFAP, 2000).
As reported in the Quantitative Usage Analysis (d ated 10/12/2001) completed by the Biological and Economics Analysis Division of OPP/EPA for PCNB for the years 1990–2000, the crops with the highest percentages of the total number of pounds of PCNB (active ingredient) applied domestically during those years were turf (49%), cotton (27%) and potatoes (9.9%). For that time period, the annual estimated total domestic use averaged approximately 1,825,000 lbs activ e ingredient (BEAD, 2001). Crops with the highest percentage of their total U.S. planted acres treated w ith PCNB were brussels sprouts (13%), cotton (5%) and potatoes (3%); no other crop had more than 2% of acreage treated with PCNB (BEAD, 2001). Crops with the largest amount of acreage treated with PCNB during that time period were cotton (700,000 ac), potatoes (45,000 ac), beans/peas (green; 15,000 ac), peanuts (10,000 ac) and tobacco (10,000 ac; BEAD, 2001). The use of PCNB on tobacco reportedly ended in 1997 (BEAD, 2004); tobacco is not a currently registered use for PCNB.
Geographic Regions of Major Use Sites
The Registrants reported that cotton and peanut use sites are predominantly in the south; potato use sites are usually in the Pacific Northwest and the Gr eat Lakes regions; turf use sites for snow mold ( Typhula spp . and Microdochium nivale ) control are mainly in the Great Lakes region; and geographic regions for seed treatment are “evenly distributed depending upon crop.” The states with the highest usage of PCNB on agricultural cropland, based on data from 1990–1998 (as re ported in the National Pesticide Use Database), include California, Florida, Arkansas and Texas (NCFAP). Based on information obtained for the 1992 Census of Agriculture, the heaviest usages of PCNB per unit area (>5 lbs per square mile of county/yr) occurred in large parts of TX, MS, TN, AL, and GA; and in smaller parts of CA, OK, AR, SC, NC and VA (U.S. Geological Survey NAWQA website).
Based on information reported in the QUA (BEAD; 10/12/2001), the states with the most usage of PCNB in terms of the percentage of total pounds of activ e ingredient used with respect to selected major crops are: 1) turf – not reported; 2) cotton – MS, AR, LA, TN, AL, NC; 3) brussels sprouts – CA; 4) cabbage – NC, WA; 5) potatoes – not reported; 6) peanuts – TX, GA, OK, AL, AZ.14 Figure 1. Estimated uses of PCNB by crop a nd county for benchmark year 1992. Figure source: U.S. Geological Survey (USGS), NAWQA web site. Da ta were obtained from the National Pesticide Use Database maintained by the National Center for Food and Agricultural Policy. Historical Use
Total annual applications of PCNB in the U.S., in terms of pounds active ingredient (a.i.), appear to have generally decreased with time during the last sev eral decades. In 1997, just over 800,000 lbs of PCNB were applied, down from 1.6 million lbs in 1992 (NCF AP, 2000). Total PCNB released (as a fungicide) in the U.S., in pounds of a.i., was reported to be 2. 25 million in 1989, 2.52 million in 1982, and 4.23 million in 1976 (Gianessi, 1992). In the Quantitative Usage An alysis for PCNB for the years of 1990 through 2000, the estimated average annual total domestic usage was reported to be approximate ly 1,825,000 lbs. a.i. for 794,000 acres treated (BEAD, 2001).
As displayed in Figure 1 , the estimated annual agricultural use of PCNB in benchmark year1992 (based on crop acreage in 1992 and pesticide use patte rns for the years 1990–1993) was 1,694,994 lbs; cotton and peanuts were the crops receiving the highest amount of PCNB in terms of total lbs applied. As displayed in Figure 2, the estimated annual agricultural use of PCNB in benchmark year 1997 (the latest data available from the USGS) had decreased relative to benchmark year 1992, to 809,602 lbs, representing a 52% decline in total pounds of PCNB applied to agricultural crops. In terms of total lbs of active ingredient applied,15 Figure 2. Estimated used on PCNB by crop a nd county for benchmark year 1997. Figure source: U. S. Geological Survey (USGS), NAWQA web site. Data were obtained from the National Pesticide Use Database maintained by the National Center for Food and Agricultural Policy.

PCNB use on cotton declined by approximately 461,000 lbs (38%) from benchmark years 1992 to 1997. While PCNB use on peanuts and cabbage declined by 93% and 85%, respectively, during that time period, its use on cauliflower and green beans increased by 195% and 90%, respectively. However, while data from benchmark years 1992 and 1997 show changes in amounts of use (either increases or decreases), it is important to keep in mind that more recent data (post 1997) could not be located and that historical uses may not accurately predict future uses, particularly given th at pesticide uses/needs are a ffected by multiple factors, including the weather, as well as changes in economic markets for specific crops.16 ENVIRONMENTAL FATE AND TRANSPORT CHARACTERIZATION
Based on the submitted environmental fate data, its physical-chemical properties, the proposed use patterns, and information found in the published literature, pentachloron itrobenzene (PCNB) is, in general, expected to be a persistent, modera tely volatile compound that will be immobile in most soils, but may have slight or even moderate mobility in coarser (sandy) so ils, particularly those that are low in organic matter. Table 1 summarizes the physico-chemical properties of PCNB, a relatively high molecular weight compound with low water solubility. More complete informati on on the environmental fate studies can be located in APPENDIX B.
Table 1. General fate and physical-chemical pr operties of PCNB based on information from the registrant.

PARAMETER VALUE SOURCE Chemical Name pentachloronitrobenzene – Molecular Weight 295.3 -- Solubility (25 o C) 0.44 mg/L (440 ppb) -- Vapor Pressure (25 o C) 1.13 x 10 -4 mmHg – Hydrolysis Half-life (pH 5, 7, 9; 25 o C) stable MRID’s 40865301, 40972601 Aqueous Photolysis Half-life (pH 5) t 1/2 = 2.5 days t 1/2 = 26.8 hours MRID’s 42606201, 42606202 MRID 42336201 Soil Photolysis Half- life stable MRID’s 41004801, 41713201
Aerobic Soil Metabolism Half-life t 1/2 = 77, 189 days (parent only); t 1/2 = 489, 1012 days (parent plus PCA) t 1/2 = 983, 1052 days (total residues) MRID’s 42911902, 41384501, 41713202, 42112801

Anaerobic Soil Metabolism Half-life t 1/2 = 9 days, <30 days (DT 50 ; parent only); t 1/2 = 410 days (parent plus PCA) t 1/2 = 334 days (total residues) MRID’s 41203602, 42094401, 41384301, 41686001, 41713202, 42112802)

Organic Carbon Partition Coefficient (K oc ) 1588, 2912, 3870, 17508 MRID 41648201

Soil Partition Coefficient (K d , mL/g) 7.3, 15.5, 19.1, 210 MRID 41648201 Bioconcentration Factor (BCF) in fish 370-400 edible tissue 1800 viscera 960-1100 whole fish tissue MRIDs 40580202, 41200001

Based on the submitted environmental fate studies, th e major degradates of PCNB in the environment are: pentachloroaniline (PCA) and pentachlorothioan isole (PCTA), and pentachlorobenzene (PCB; which is also present as an impurity); minor degradates ar e pentachlorothioanisole sulfoxide (PCTASO), and pentachlorothioanisole sulfone (PCTASO 2 ). PCNB also contains the manufacturing contaminant hexachlorobenzene (HCB), which was de tected in seven of the eight submitted terrestrial field dissipation studies (at maximums of 0.03-0.076 ppm) as well as in an anaerobic aquatic metabolism study, at a single sampling interval, where it was present as a volatile at 0.023 ppm. Structures of the parent compound and its degradates are presented in APPENDIX C . While pentachlorophenol (PCP) was detected in two of the submitted studies (MRID’s 412036-02 & 420944-01; MRID 430615-01), and studies (Murthy and Kaufman,17 1978) in the published literature indicate that there are conditions under which PCP can form in the environment, there is not sufficient information (eith er from the submitted data or from published literature) to determine what conditions favor PCP formation and which do not. Nor is there sufficient information to quantify the amount and rate of formation of PCP from PCNB when PCP is produced.
PCNB is a moderately volatile compound that can be expected to dissipate through volatilization; however, this route of dissipation from the soil should be minimized for many uses by incorporation of the pesticide into the soil at application. Volatilization should be a more significant route of dissipation of the parent and the degradate PCA when PCNB is not incorpor ated. This will occur when the pesticide is applied as a foliar spray ( e.g. , to turf) or is applied by chemigation (through overhead sprinkler irrigation; e.g. , to potatoes. Submitted data from a laboratory vol atility study (MRID 41178001) showed that maximum volatilization occurred within 24 hours of treatment. Submitted data from a field volatility study (MRID 437511-01) showed that volatilized PCNB and PCA were both at a maximum on day 0 and declined throughout the rest of the 13-day study (although large am ounts of rain which fell during study days 3 to 9 may have altered the volatilization rate relative to that which might occur under more typical field conditions). It has been observed that PCNB may vola tilize more from moist or saturated soils relative to dry ones due to decreased adsorption in the wetter soils (Casely, 1968). Casely (1968) reported that greater than 2/3 of the approximately 80% of the applied PCNB th at was lost from soil during 10 months of incubation was due to volatilization, with the remaining losses attri buted to microbial degradation. Data on volatilization from foliar surfaces were not available. Large Henry’ s Law constants for the degradates PCA, PCTA, PCB and PCP (on the order of 10 -7 to 10 -4 atm-m 3 -mol) indicate that volatilization may also be an important environmental fate process for these compounds.
The primary degradation pathway for PCNB is aqueous photodegradation when the compound is present in an unsorbed state in clear and sha llow surface water under favorable light conditions. Photodegradation of PCNB in surface water is moderate ly rapid, with half-lives on the order of a few days or less. While evidence of aqueous photodegradation of PCNB was not found in the scientific literature, OPP found the two submitted guideline studies (MRID 423362-01; MRIDs 426062-01 and 426062-02) acceptable and, therefore, used the half-life values determin ed in those studies to assess the compound’s fate in the environment. However, direct photolytic degradation of PCNB in turbid and/or deeper waters may be limited by the attenuation of sunlight due to unfavorable conditions. Thus, cauti on must be used in extrapolating laboratory photolysis data to the environment. Also , adsorption of the compound to suspended particles in the water column will decrease the amount of compound available for photolytic degradation.
PCNB is stable to hydrolysis and is effectivel y stable to photodegradation on soil (half-life of 80 days). PCNB biodegrades slowly in aerobic soils , with submitted guideline study data (MRID 429119-02; MRIDs 413845-01, 417132-02, and 421128-01) showing half-lives of 77 and 189 days. Data from published literature also indicate that PCNB will be degraded sl owly in aerobic soil, with half-lives of 4.7-9.7 months reported by Wang and Broadbe nt (1972) and half-lives of 213, 425, 535 and 699 days reported by Beck and Hansen (1974). While PCNB is onl y expected to biodegrade slowly in most aerobic environments, it is biodegraded more rapidly (DT 50 's of <30 days in soil based on submitted data) in anaerobic soil environments. Although guideline study data on the a quatic metabolism of the compound we re not submitted, data in the literature showed a rapid biodegrad ation of PCNB in anaerobic estuari ne sediment (previously exposed to anthropogenic compounds from nearby industry), with a reported half-life of 0.8 days (Susarla et al. 1996). Ko and Farley (1969) also reported rapid degradation in anaerobic (flooded) soil, with a reported half-life of approximately 2 weeks. However, while Schauerte et al. (1982) found a quantitative conversion of PCNB to the degradates PCA and PCTA in the sediment phase of an experimental pond study, Susarla et al. (1996) found that in anaerobic sediment, PCNB degraded to multiple less-chlorinated anilines following the initial conversion to PCA. In submitted guideline terrestrial field dissipation studies, PCNB dissipated more rapidly18 in the plots in which the pesticide was not incorpor ated, with a half-life range of 39-57 days (MRIDs 430615- 01; 438874-03; 41210501,420944-03 and 420944-04) versus a half-life range of 128-324 days (MRIDs 438874-01; 438874-02; 417214-01; 412164-01 and 424859-01; 412164-02 and 424859-02) for plots with incorporated PCNB. Major degradates in those st udies included PCA, PCTA and PCB. Although PCB is present as a manufacturing impurity in PCNB, increases in its concentration over time confirmed that it was formed as a degradate of PCNB in the field. The ma nufacturing contaminant HCB was detected in all except one of the field studies, at maximum concentrations ranging from 0.03 to 0.076 ppm. In a study of field soils (cropped with potatoes) in Denmark to which PCNB ha d been applied over the previous 5 to 11 years, Beck and Hansen (1974) determined field half-lives rangi ng from 117 to 1059 days, with a mean of 434 days (for 22 values). Degradates observed in the Danish field soils were PCA, PCTA and PCB.
PCNB is immobile in most soils, but may have slight or even moderate mobility in soils low in organic matter, as its adsorption correlates well with organic carbon content. Data from batch equilibrium studies, when considered along with results from Tier I ( APPENDIX D1 andD3 ) screening models, Tier II ( APPENDICES D2 and D4 ) refined models and guideline terrestrial field dissipation studies, indicate a low potential for leaching to groundwater. Because adsorpti on of the compound is related to soil organic carbon content, a slightly higher, though still low, potential for leaching to groundwater might exist for PCNB in soils which are relatively low in organic matter, as is often the case with coarse-textured soils. In an experimental small pond study conducted in Germany, PC NB did not leach below the 15- to 20-cm sediment layer and did not leach significantly into the adjacent soil (Schauerte et al. 1982). Based on submitted guideline study data (MRIDs 435005-02; 435005-01 ), the major degradates pentachloroaniline (PCA) and pentachlorothioanisole (PCTA) are expected to be immob ile in soil. Data reported in the literature indicates that PCB will have slight mobility in soil (Forst et al. 1994) or will be immobile (Sabljic et al. , 1995); the latter author also reported a K oc for PCA indicating it will be immobile in soil. These data are in basic agreement with observations made in the submitted terrestrial field dissipation studies, in which PCNB generally did not leach below the 6- to 12-inch soil depth; and PCA, PCTA and PCB generally remained in the 0- to 6-inch soil depth, although PCA and PCB leachedinto the 6- to 12-inch soil depth at some sites.
There is a potential for PCNB to reach surface wa ter through spray drift when applied using ground spray, as would be utilized for many of the labeled u ses. Greater spray drift will be associated with foliar applications (such as to turf), while in-furrow applica tions (such as to cotton and peanuts) should result in relatively lower levels of drift. Uses such as seed trea tment and drench application, used for many of the labeled crops, should not result in spray drift. Because PCNB and its major degradates are all generally persistent under field conditions, ove r time the compounds may be present in field runoff and could thus reach surface water bodies. The slow biodegradation of PCNB in most soils will increase the potential for both groundwater and surface water contamination. Howeve r, the potential for groundwater contamination should be decreased by the tendency of the compound (and its major degradates PCA and PCTA) to adsorb to surface soils. While PCNB is likely to adsorb to aquatic sediments, the potential for the compound to accumulate in such environments may be decreased by the more rapid degradation of the compound in anaerobic conditions. Based on information reported in th e literature, PCNB will rapidly be degraded to PCA in anaerobic sediment, with subsequent transforma tion of that compound to lesser-chlorinated anilines (Susarla et al. , 1996). However, Schauerte et al. (1982) only reported a quantita tive conversion of PCNB to the degradates PCA and PCTA in the sediment phase of an experimental pond study. In the Schauerte et al. study, the majority of PCNB residues remaining in the sediment at up to 145 weeks post-treatment were present in the 0- to 10-cm layer, but decreased with tim e. Overall, information on the rate and products of biodegradation in both aerobic and anaerobic aquatic systems is limited and guideline studies were not submitted. Additional information is needed to accurately assess the potential for accumulation of PCNB and/or its biodegradation produc ts in aquatic environments.19 Based on the results of a guideline study (MRID 405802-02 ), PCNB has a very high potential to bioaccumulate in fish, but is metabolized in such, and will undergo moderately rapid depuration when the fish are no longer exposed to the compound. Residues in bluegill sunfish exposed to [ 14 C]PCNB at # 1.0 ppb were bioaccumulated to a greater extent in the viscer a, with bioconcentration factors (BCF) of 1800X in each of two studies, versus in edible tissue, with BCF’s of 370X and 400X; in whole fish tissue, measured BCF values were 960X and 1100X. As reported in the lite rature, PCNB was bioaccumulated in rainbow trout exposed to PCNB at 0.69 ppm, with BCF’s of 114-261X (Niimi et al. 1989). A BCF value of 238X was reported for PCNB in topmouth gudgeon (Kanazawa, 1981). Reported BCF values for guppies exposed to PCNB range from 363 to 1030 (DeWolf, 1992). Higher BCF values have been reporte d for aquatic plants. Korte et al. (1978) reported BCF values of 14,000X a nd 20,000X for PCNB in algae; and Wang et al. (1996) reported 4508X for PCNB in Chlorella fusca . However, the values reported by Korte et al. were determined on a dry-weight basis; on a wet-weight basis (as u sed in other studies) the high value of 20,000X would decrease to a BCF of 3100X.
For the purposes of the drinking water assessment (DWA) and the ecological risk assessment (ERA), half-lives were recalculated using parent data plus data for some of the degradates, as appropriate. To determine the half-lives, the concentrations of the pare nt and appropriate degradate(s) were summed, and halflives were calculated normally (using first-order linear re gression). Degradation kinetics for the parent and the various degradates were not determined separately and then comb ined. The approach used by EFED, while conservative, should not overly lengthen the hal f-life estimates relative to such estimates determined using individual kinetic rates for each compound, given that EFED is interested in the overall half-life for the residues of interest (PCNB and PCA for drinking wa ter and total residues for ecological ponds). The continuous formation and decline of degradates in a sequential manner does not affect the half-lives calculated using this approach, as the other major degradate, PCTA (which was only present as a minor degradate in three of the four soil metabolism studies), is formed from PCA in the proposed metabolic pathway.

Volatiles were included when half-lives were r ecalculated because it was assumed that volatilization from the small (e.g., 10 g) soil samples incubated in tubes in the laboratory under ideal conditions would likely be greater, on a relative basis, than would occur in the field when the pesticide is incorporated into the soil (with an intended goal of decreasing volatilization). The pattern of volatilization observed in one of the submitted aerobic soil metabolism studies, in which volatiliza tion was minimal at first (only 9% of the applied by 60 days) and increased with time, was questionable because it did not agree with the pattern observed in both the field (MRID 437511-01) and laboratory (MRID’s 411780-01, 425074-01) volatilization studies in which the majority of the volatilization occurre d during the initial 24 hours following treatment. Additionally, the use of an in-furrow application (or othe r type of incorporation) should theoretically reduce the level of volatilization of PCNB in the field. Insubmitted field studies, dissipation was more rapid (halflife range of 39-57 days) in the plots in which the pes ticide was not incorporated relative to dissipation (halflife range of 128-324 days) for plots with incorporated PCNB. Therefore, it would likely be underestimating the remaining level of the pesticide in the field ( i.e. , in soil) to assume that the ha lf-life determined in the lab, which was affected by the high level of volatilization that occurred, would be representative of what might occur in the field in the case of a volatile compound like PCNB.

When the half-lives were recalculated for use inthe DWA using concentration data (including volatiles) for the parent compound plus the degradate PCA, th e recalculated aerobic soil metabolism half-lives for the parent and parent/PCA combination ar e 489 days and 1012 days, respectively (MRID’s 42911902, 41384501, 41173202, 42112801). The recalculated value for the anaerobic soil metabolism half-life for the parent plus PCA combination was 410 days (MRID 413843- 01). When the half-lives were recalculated using20 concentration data (including volatiles) for total residues (defined here as including only the following compounds of interest: PCNB, PCA, PCTA, PCB, PCP, PCTASO, PCTASO 2 and/or HCB) for use as estimated environmental concentrations for the eco logical exposure assessment, the recalculated aerobic soil metabolism half-lives for total resi dues were 983 da ys and 1,052 days. The recalculated value for the anaerobic soil metabolism half-life for total residues was 334 days.
Monitoring Data
Limited monitoring data (post-1990) were found fo r PCNB and its major degradates PCA and PCTA in water, sediment and air. Water monitoring data are discussed in the Water Resources section of the chapter. Available monitoring data for the degrad ates PCB and PCP are not presented here as PCNB is not the single source for these compounds in the environmen t and the available monitoring data could not be linked to the use of PCNB.

Soil and Sediment
In a U.S. Geological Survey (1992-1995) monitoring study of semi-volatile organic compounds in streambed sediment at 536 sites in 20 U.S. major river b asins, PCNB was detected at only 0.2% of the sites, at a maximum concentration of 180 μg/kg (Lopes and Furlong, 2001). Based on information in the NAWQA database, PCNB was not detected in bed sedimentat 605 sites in 45 states during 1992-2001 with three exceptions: It was detected in Boulder Co., CO (9 μg/kg); Adams Co., CO (10 μg/kg); and Hillsborough Co., FL (180 μg/kg). In California, the state with the hi ghest usage of PCNB, the compound was not detected in the bed sediments at any of the NAWQA sampling s ites at any sampling date (NCFAP; Pesticide Use Database, 2000).
In samples from 982 counties in 48 states collected in 1992-2001, the degradate PCA was not detected in the NAWQA bed sediment samples above the limit of detection (1 μg/kg) for the majority of the sampling sites and dates. It was detected at 0. 20-3.8 μg/kg in samples from Greene and Warren Counties in Ohio, and in Cook County, Illinois. In 1988-1990 studies of suspended sediment in the Mississippi River and its main tributaries, PCA was detected in the spring times at a range of 0.76 to 7.4 μg/kg and in the summers at a range of 0.08 to 1.4 μg/kg (Rostad et al. , 1993; Rostad et al. , 1999).
Based on information presented in the National Ins titute of Health/National Library of Medicine’s Hazardous Substances Data Bank (HSDB; http://toxnet.nlm.nih.gov) , PCA has been detected at a range of 0.1-3.75 ppm in soil samples from a field previously treat ed with PCNB. In a study of soil from a field in which PCNB was used extensively, PCA was detected at 10.1 ppm. Samples of agricultural field soils from Belgium and Denmark contained PC A at a range of 0.85-2.5 ppm.
Monitoring data for soil/sediment could not be located for the degradate PCTA.

Air
In a study of air samples collected in 1994 over areas of non-farmed land near Larimore, ND, PCNB was detected in 1 of 7 samples, at a concentration of 0.0017 ng/m 3 (Hawthorne et al., 1996). In air monitoring studies done in Canada, PCNB was detected over Sask atchewan despite no evidence of the application of PCNB in that area. PCNB was detected in 10 of 11 samples (at 0.01-1.60 ng/m 3 ) collected during a 3-month period in the summer of 1994 over Regi na, Canada, and in 2 of 5 samples collected during that time over Waskesiu, Canada; the compound was not detected in any of 7 samples collected over Yellowknife, Canada21 (Thompson et al., 1997). The detection of PCNB in th e atmosphere over areas in which the pesticide was not used is evidence of the possibility for long-range transport of the compound. It is noted that PCNB is a listed Hazardous Air Pollutant (HAP) for which standards must be set under the Clean Air Act (amended 1990). PCNB is not listed on the U.S. EPA’s list of Persistent Organic Pollutants (POPs) as found at http://www.epa.gov/oppfead1/international/pops.html.
In an air monitoring study of pesticides in Lompoc , California, PCNB was detected in ambient air at a maximum acute (24-hr) concentration of 48 ng/m 3 , a maximum subchronic concentration of 18 ng/m 3
, and a maximum chronic concentration of 8.5 ng/m 3 (CDPR 2003; http://www. cdpr.ca.gov/docs/dprdocs/lompoc/lompoc.htm ).
In a study of long-range transport of organochlorin es based on detection in the snow of the Canadian Arctic, PCA was one of the most prominent pollutants found (Welch et al. 1991). PCA was detected at a mean concentration of 1230 pg/L in melted snow and a particle concentration of 4.3 μg/kg.
Air monitoring data could not be located for the degradate PCTA.

WATER RESOURCES ASSESSMENT

This section identifies the data used as the source of the input parameter values, as well as the actual input parameter values, used in m odeling to determine the Estimated Dr inking Water Concentrations (EDWC) for the drinking water assessment and the Estimated Envi ronmental Concentrations (EEC) for the ecological risk assessment; and specifies which values are to be u sed as EDWC’s or EEC’s for the two risk assessments.
In determining surface water EDWC’s for the drinking water assessment and the EEC’s for the ecological risk assessments, OPP utilized the Tier II screening models PRZM/EXAMS; groundwater EDWC’s for the drinking water assessment were gene rated using the Tier 1 screening model SCI-GROW. The EDWC’s recommended by OPP for use in the hum an health risk assessment for PCNB are presented in Table 2 . Reported values represent the maximum contam ination levels resulting from the labeled uses (excluding ornamental, greenhouse or residential uses, as well a geographically restricted use on turf) listed in the 1700+ uses on the labels, as presented in EPA’s LUIS report for labels accepted as of 2/20/02 (LUIS Report Run date 6/28/02). The EEC’s utilized by O PP for use in the ecologi cal risk assessment for PCNB are presented in Table 3 . The general fate and physical-chemical pr operty data used as the source of the input parameter values for modeling were obtained from th e guideline studies and other submissions from the registrant.22 Table 2. EDWC’s for the drinking water assessm ent based on PCNB use on turf in Pennsylvania (surface water) and bulb crops (groundwater). Source Crop EDWC Surface water drinking water Turf acute: 440 μg/L (ppb) 1 1-in-10-years annual mean (chronic): 65.5 μg/L (ppb) 30-year mean: 33.7 μg/L (ppb) Groundwater drinking water Bulbs 30.6 μg/L (ppb) 2

1 Surface water EDWC values were generated using the PRZM/EXAMS m odel with a foliar/ground spray to turf in Pennsylvania applicat ion scenario (two applications of 33.67 lb a.i./A, at a 21-day interval). The actual output value from PRZM/EXAMS was 587.7 ppb for the c abbage use acute concentration. However, as this is greater than the aqueous solubility of 440 ppb at 25 o C for PCNB, the solubility limit should be used instead.
2 Groundwater EDWC’s are based on PCNB use on bulb crops at 213.4 lb a.i./A/application in a single application.

Table 3. Surface water EEC’s for eco logical risk assessment based on PCNB 1 use on various crops.

Crop Acute (ppb) 1-in-10 Year 21-day Concentration (ppb) 1-in-10 Year 60-day Concentration (ppb) 1-in-10 Year 21-day Benthic Concentration (ppb)
Turf 259 187 139 106

Peanuts 97 46 25 33 Cabbage 84 56 36 21

Potatoes 22 11 5 4

Cotton 28 20 14 12

1 half lives are calculated based on total residues. A separate drinking water assessment was conducte d previously by OPP for the manufacturing contaminant HCB, which was detected at low levels (0 .03-0.076 ppm) in seven of the eight terrestrial field dissipation studies conducted using PCNB . The contaminant was also detected as a volatile at a single sampling interval in an anaerobic aquatic metabo lism study. The drinking water assessment conducted was also for the manufacturing impurity/minor degradat e PCB. The assessment essentially concluded that, based on both modeling results and monitoring data, both HC B and PCB are relatively unlikely to contaminate groundwater and that long-term concentrations in su rface water will not exceed 0.01 ppb (10 pptrillion). The DWA memo is attached as APPENDIX D4.

Surface Water
The EDWC’s/EEC’s for surface water bodies were determined using the Tier II screening-level simulation models PRZM (v. 3.12; input generated by PE4VO1.pl, dated 8/8/03) and EXAMS (2.98.04). Input parameter values utilized for PRZM/EXAMS modeling are presented in Table 4 . EDWC’s for surfacewater derived ( Table 5 ) and SCIGROW estimated groundwater-derived EDWC’s ( Table 6 ) are used for the human health risk assessment Additional information on the models PRZM and EXAMS can be located at: http://www.epa.gov/oppefed1/models/water/

. Some of the input values have been changed since the initial Tier II DWA conducted in 12/2003, most notably the incorporation depths and CAM numbers (which reflect pesticide application practices) used for some of the crops. The incorporation depth va lues used here were obtained from specific labels, as indicated in Table 2. Another change affecting th e EDWC’s was the correction of model output values (for23 drinking water only) to account for the Percent Cropped Area; this was not done in the 12/2003 DWA (despite statements which indicated such). While th e anaerobic aquatic metabolism half-life input value was also changed, it did not have any effect on the EDWC’s.
The five agricultural or recreational (turf) uses of PCNB chosen to represent the use of the compound in the environment are turf, peanuts, cabbage (cole cr op), potatoes and cotton. To simulate these uses, OPP used a standard Pennsylvania turf scenario, a standardNorth Carolina peanuts scenario, a standard Florida cabbage scenario, a standard Idaho potatoes scenario, a nd a standard Mississippi cotton scenario. Application dates were chosen based on whether PCNB is applied as a pre- or post-emergent to the respective crops as well as on reported planting dates found in the USDA agricultural crop profiles at www.pestdata.ncsu.edu/cropprofiles. Separate simulations were perfo rmed to determine estimated water concentrations for the human health (drinking wa ter component) risk assessment and the ecological risk assessment. The human drinking water EDWCs were dete rmined using the standard index reservoir scenario in which a 172-ha field drains into a 5.3-ha r eservoir and percent cropped area (PCA) is taken into consideration. The PCA for each of the four crops m odeled except turf is the default value of 0.87; a value of 1.0 is used for turf. While cotton has a PCA of 0.20, the default PCA of 0.87 was used in light of the fact that other crops which receive PCNB may be grown on the same cropland. The surface water EEC’s for the ecological assessments were determined using the standa rd pond scenario in which a 10-ha field drains into a 10,000-m 2 pond, 2-m deep, with the assumption that the small field is cropped at 100%. Complete PRZM and EXAMS output files can be found in APPENDIX D5. Chemical property input values were chosen according to the current EFED standard guidance document ( Input Parameters in Modeling the Environmental Fate and Transport of Pesticides, Version II , February 28, 2002).24 Table 4. PRZM/EXAMS input parameter values for PCNB plus PCA for the drinking water assessment.

Parameter Value Source and/or Comments

Application Rate (lb a.i. /A/application) turf: 32.67 peanuts: 10 cabbage (cole crop): 30 potatoes: 25

cotton: 2 Reg. 5481-419 (LUIS line 1524) Reg. 5481-472 (LUIS line 1405)

Reg. 400-453 (LUIS line 360) Reg. 5481-450 (LUIS line 1503)

Reg. 400-399 (LUIS line 630)
Number of Applications turf: 2 peanuts: 1 cabbage: 1 potatoes: 1 cotton: 1 Reg. 5481-419 Reg. 5481-472 Reg. 400-453 Reg. 5481-450 Reg. 400-399
Interval Between Appli cations (days) turf: 21 peanuts: Not Applicable (NA) cabbage: NA potatoes: NA cotton: NA Reg. 5481-419

–

–

–

-- Date of First Application turf: November 15 (post-emergent) peanuts: April 15 (pre-plant) cabbage: August 15 (pre-plant) potatoes: May 20 (pre-plant) cotton: April 20 (pre-plant) Based on USDA Crop Profiles information located at http://pestdata.ncsu. edu/cropprofiles/

Application Type, and Depth of Incorporation (cm), CAM input turf: foliar/ground spray; 0 cm; CAM = 2 peanuts: band/ground spray; 0 cm; CAM = 1 cabbage: broadcast spray; 10 cm; CAM = 4 potatoes: granular; 10 cm; CAM = 4 cotton: in-furrow spray; 0 cm; CAM = 1 Reg. 5481-419 Reg. 5481-472 Reg. 400-453 Reg. 5481-450 Reg. 400-399
Soil Partition Coefficient (K d ; mL/g) 15.5 MRID 41648201; lowest non-sand K d Aerobic Soil Metabolism Half-life (days) t 1/2 = 1555 days (parent plus PCA) MRID’s 42911902, 41384501, 41713202, 42112801; represents the 90 th percentile of the upper confidence bound on the mean of 2 half-life values
Spray Drift Fraction (ground spray) 0.01 Input parameter guidance
Application Efficiency 0.99 Input parameter guidance
Molecular Weight 295.3 g/mole Product chemistry data
Vapor Pressure 1.13 x 10 -4 Torr Product chemistry data
Henry’s Law Constant 4.42 x 10 -5 atm-m 3 -mol Product chemistry data
Solubility in Water at 25 o C (ppm) 4.4 ppm set at 10X solubility limit of 0.44 ppm based on input parameter guidance
Aerobic Aquatic Metabolism Half-life (days) t 1/2 = 3110 days (parent plus PCA) input value is 2X the aerobic soil metabolism half-life input value as in input parameter guidance
Anaerobic Aquatic Metabolism Half-life (days) t 1/2 =1460 days (parent plus PCA) input value is 2X the anaerobic soil metabolism half-life value (as in input parameter guidance); calculated using

source data from MRID 41384301
Hydrolysis Half-life @ pH 7 (days) stable MRID’s 40865301, 40972601Parameter Value Source and/or Comments

25 Aquatic Photolysis Half-life @ pH 5 (days) 1.83 MRID’s 42606201, 42606202, 42336201

Table 5. PRZM/EXAMS surface water EDWC result s for PCNB plus PCA for the drinking water assessment.

Crop Percentage Cropped Area PRZM/EXAMS Results (ppb)
acute 1-in-10 year 30-year average

Turf 1.0 440 1 65.50 33.73

Peanuts 0.87 195.1 13.87 7.04 Cabbage 0.87 164.6 14.28 7.73

Potatoes 0.87 27.80 2.53 1.47

Cotton 0.87 53.73 6.48 3.16

1 The actual output value from PRZM/EXAMS was 587.7 ppb for the turf use acute concentration. However, as this is greater than the aqueous solubility of 440 ppb for PCNB, the sol ubility limit should be used instead.

Table 6. SCI-GROW2 input parameter values a nd results for pentachloronitrobenzene (based on PCNB plus PCA) applied to various crops by soil or foliar applications only.

Parameter Value
Maximum Application Rate (lb a.i./A/application) turf: 32.67 peanuts: 10 cole crops: 30 potatoes: 25 bulb crops: 213.4
Maximum Number of Applications per Year turf: 2 (21-day interval) peanuts: 1 cole crops: 1 potatoes: 1 bulb crops: 1
Aerobic Soil Metabolism Half-life (days) t 1/2 = 750.5 days (parent plus PCA; average of two values)
Organic Carbon Partition Coefficient (K oc ) 1588 (lowest value of four; based on parent compound only) (MRID 41648201)
Results (Estimated Drinking Water Concentrations for groundwater, in ppb) turf: 9.38 peanuts: 1.44 cole crops: 4.31 potatoes: 3.59 bulb crops: 30.6

The use of the Pennsylvania standard scenario is b ased on the registrant’s information that PCNB is used on turf (as a post-emergent), to prevent snowmold, mainly in the Great Lakes regions. An application date of November 15 thwas chosen to represent a post-emergent application (generally done prior to26 Thanksgiving) made during the part of the growing season in which snow mold occurs (November through April). Incorporation of the pesticide was not mode led, as the application simulated was a post-emergent (foliar/ground) spray. The application rate and timi ng were obtained from a registered label (Reg. 5481-419). Although there is a higher (43.56 lb ai/A, applied twice at a 7-day interval) maximum rate for turf than the one modeled, it is an allowed usage only in California, Washington, and Oregon.

The use of the Florida standard scenario for cabbage is based on the pesticide survey usage information that the crop with the highest usage in te rms of its total U.S. planted acres treated with PCNB is the cole crop brussel sprouts. However, because EFED did not have a standard modeling scenario available for brussel sprouts, cabbage (which is treated at the same rate as brussel sprouts) was chosen as the representative cole crop. An application date of August 15 thwas chosen for a pre-plant application of PCNB based on a planting time of August to February in north east Florida, where 50% of the state’s cabbage acreage is located. The application simulated represents a ground spray with an incorporation to 10 cm. The application rate and depth of incorporation were obtained from a registered label (Reg. 400-453).
The use of the North Carolina peanuts and the Mi ssissippi cotton standard scenarios are based on the registrant’s information that PCNB is used on those cr ops predominantly in the south. An application date of April 15 thwas chosen for a pre-plant application to peanuts based on a planting time of April 20 thto May 20 th . An application date of April 20 thwas chosen for a pre-plant application to cotton based on a May 1 st planting time. The application simulated for both cr ops represents a ground spray with no incorporation. Although the application to cotton is in-furrow (T-band) and incorporation of some of the pesticide to 1⁄2-1 inch (the seeding depth) would occur, this type of a pplication at such a shallow depth is best modeled as a broadcast with no incorporation (R.David Jones, EFED; Personal Communication 7/04 ). The application rates and depths of incorporation were obtained fro m respective registered labels (Reg. 5481-472 and Reg. 400-399).
The use of the standard Idaho potatoes scenario is based on the registrant’s information that PCNB is used on that crop mainly in the Pacific Northwest a nd the Great Lakes regions. An application date of May 20 thwas chosen for a pre-plant application to potatoes based on a planting time of April to June 10 thfor eastern Idaho, where the majority of the crop is grown in the state. The application simulated represents a granular formulation with an incorporation to 10 cm. The application rate and depth of incorporation were obtained from a registered label (Reg. 5481-450).
Drinking Water EDWC’s (Surface Water)
The data previously presented in Table 2 reflect the use of PCNB on turf in Pennsylvania at an application rate of 32.67 lb a.i./A/app lication, applied twice (total application rate of 65.3 lb a.i./A) at a 21- day interval as a post-emergent foliar/ground spray appli cation. That modeling scenario was chosen for use in the human health risk assessment because it represents one of the highest single application rates on the labels (with the exception of bulb crops, for which a st andard scenario was not available, or a Special Local Need use on turf in California, Washington and Oregon only), and results in the highest EDWCs. Table 5 presents input parameter values utilized for PRZM/E XAMS modeling and the resultant EDWCs for the five use scenarios (Pennsylvania turf, North Carolina peanut s, Florida cabbage, Idaho potatoes, Mississippi cotton) for which modeling was conducted. The use scenarios were chosen for the high application rates and/or for the high usages (in total lb. active ingredients) associated with those crops in the U.S.
In response to a decision made by the Health Effect s Division’s Metabolism Assessment Review Committee (MARC), the reviewer conducted the dr inking water modeling to account for the parent1 Personal communication, Lawrence Burns, Office of Research a nd Development, United States Environmental Protection Agency, Athens, GA

27 compound plus PCA, a degradate considered to be a resi due of concern. In this approach, the aerobic and anaerobic soil metabolism half-lives were calculated usi ng concentration data (including volatiles) for the parent compound plus PCA. Because separate aqueous photolysis data were not available for PCA, the photolysis half-life used in the modeling was calculate d using parent compound concen tration data only. The lack of information on the photolysis rate of PC A comprises an uncertainty surrounding the surface water EDWCs.
Additionally, the reviewer used soil adsorption coefficients determined only for the parent compound; however, other available information from the guideline studies indicates PCA has soil mobility characteristics similar to that of the parent compound. Again, the use of parent data only for this input parameter increases the uncertainty surrounding the surface water EDWCs as well as the groundwater EDWC. Because of other conservative assumptions usedin modeling, the generated EDWCs should provide a reasonable upper bound estimate of potential concentrations of the parent plus degradate that may be found in surface water or groundwater in the environment.
In addition to uncertainty associated with mode ling inputs, there is an uncertainty component associated with limitations of the Tier II models ( i.e. , PRZM/EXAMS). One particular uncertainty in the EDWC’s which warrants some further discussion is how th e effects of solubility have been handled in this assessment. In the environment, solubility places an upper limit on the concentration in solution (not including any suspended solid material) at a particular temperature. While concentrations higher than the solubility do occur ( i.e ., supersaturation), they are highly unlikely in the environment, given the large number of nucleation sites (soil and organic matter particles) av ailable on which precipitation reactions can start. Due to the restrictions in place in the EXAMS model, it ca nnot simulate an aqueous concentration that saturates the water body at the aqueous solubility limit of th e compound, as EXAMS does not use the solubility input parameter as the direct upper limit on concentration. Ingeneral, the model disregards a portion of the mass of the compound once the concentration of that co mpounds exceeds a set limit (50% of the solubility), thereby effectively removing some mass and making it unavailable from that point onward so that it cannot be reintroduced into the water phase even as the compound is degraded. This is done as a way to reflect Freundlich adsorption behavior in EXAMS 1 . Unfortunately, the removal of mass from the system when onehalf the solubility is exceeded tends to overestimate th e removal of the substance from the environment. In addition, it prevents EXAMS from reflecting concentra tions in the environment higher than one-half the solubility, even though they can physically occur. C onsequently, OPP’s policy is to multiply the solubility by 10 (to obtain the input parameter value) to prev ent EXAMS from using the solubility dependent routines. While this does not change the results ( i.e., the model output values), it does allow for output values that exceed the solubility limit (at the modeled temperature of 25 o C). In cases where the resulting EDWC’s are greater than the solubility, they are reported as e quivalent to the solubility limit (440 μg/L at 25 o C). It is thought that this better reflects the fate of the pestic ide in the environment for the purposes of the drinking water and ecological risk assessments.

For use in the human health risk assessment, EFED recommends an acute surface water EDWC of 440 ppb and a chronic EDWC of 65.5 ppb, both based on the use of PCNB on turf at a rate of two applications of 32.67 lb a.i./A at a 21-day interval. Note that the value “440 ppb” is the aqueous solubility limit of the parent compound at 25 o C. While the use of PCNB on (ornamental) bulb crops at an application rate of 213.4 lb a.i./A/application (single applicati on) may result in higher values, OPP does not have a standard modeling scenario available to simulate app lication to (ornamental) bulb crops. Since the model28 results for turf were an estimated acute concentra tion which was equal to the solubility limit for the compound, the predicted acute concentration for bulb crops could not be higher (thus, more conservative) than the one ( i.e ., 440 ppb) recommended for use in the human h ealth risk assessment. Also, although there is a higher ( 

### a greater) maximum rate for turf than the one u sed to determine EEC’s, it is an allowed usage only in California, Washington, and Oregon. Based on the higher turf application rate of 43.56 lb a.i./A applied twice at a 7-day interval, the acute EDWC was 18.4% greater (696 ppb vs . 588 ppb) and the chronic EDWC was 32.9% greater (87.1 ppb vs . 65.5 ppb).
Based on modeling results from a provisional ve rsion of PRZM/EXAMS (PRZM9; dated November 10, 2004), for which a QA/QC has not yet been comp leted by EFED, the estimated acute surface water concentrations from turf use are predicted to decr ease by 26.5%, from the previous value of 586.4 ppb to 431.9 ppb, when volatilization is accounted for. Ho wever, because the solubility limit of 440 ppb is used for the EDWC (in lieu of the model output valu e of 586.4 ppb), the effective decrease from taking volatilization into account is only 1.9% for acute expos ure. Chronic drinking water exposures for turf use are predicted to decrease by approximately 34%, from 65.3 ppb to 43.4 ppb. Detailed information on the modeling and complete results are presented in Appendix D6.
Drench Applications
While previous versions of the risk assessment cont ained a discussion of the drench application and resulting surface water concentrations, this has been removed from the revised chapter. Additional information obtained from the registrants following the receipt of the comments helped to clarify apparent discrepancies concerning the use of drench applicati on, as mentioned in the error only comments and then the public comments from the registrant. EFED was able to determine that the drench use and rates did not represent a maximum rate (among all uses) and was not a major use for PCNB; thus, modeling for drench uses is not necessary.
Refinement of Estimated Surface Water Co ncentrations for Golf Course Turf Use
Because the majority of PCNB use on turf is on golf course turf, estimated surface water concentrations for both the drinking water and ecologi cal exposure assessments were adjusted to account for pesticide use on less than the total turf acreage. Golf course facilities c onsist of separate playing areas that are classified as tees, greens, practice green, fairways , driving range, and roughs, in addition to “unmanaged grounds” where lakes, ponds, out-of-play areas, conserva tion areas, and buildings are located. Management practices and intensity vary with the type of playing area, and it is common for pesticides to be applied only to tees,greens and fairways. Based on the registrants’ formally documented intention to restrict PCNB use on golf course turf to tees, greens and fairways, and to exclude roughs, a “Golf Course Adjustment Factor” (GCAF) was applied to the EDWC ’s and EEC’s determined using the Tier II model PRZM/EXAMS. However, the GCAF is only applicable to golf course use scenarios, and cannot be used to modify estimated surface water concentrations associated wtih sodgrass fa rm, residential, right-of-ways, (other) recreational, or any other turf uses. As the PCNB labels allow for ot her turf uses, the adjusted values are to be considered separately and will not be used in place of the turf use values reported for the drinking water and ecological exposure assessments.
To refine the EDWC’s (surface water) and EEC’s for PCNB for golf course turf use on tees, greens, and fairways, the EDWC’s and EEC’s were multiplied by 0.27 based on the premise that tees and greens account for a total of approximately 4% of total managed golf course turf and fairways account for 23%. Adjusted values are presented in Table 7 . The GCAF should not be considered to be analogous to a29 Percentage Crop Area (PCA) factor, which is applicable only to agricultural crops and refers to the fraction of a watershed that is planted with a particular crop. Because the GCAF is not analogous to a PCA, but is merely a correction factor to account for the partial land area treatment of total golf course acreage, the GCAF has been applied here to the EDWC’s usedin the drinking water assessment as well as to the EEC’s used in the ecologi cal exposure assessment. The GCAF has not been applied to the groundwater values determined using the Tier 1 model SCI-GROW, because th e model is based on a treated field rather than a watershed.
While the implementation of a GCAF will allo w for a modification of the EDWC’s and EEC’s determined by EFED Tier 1 and Tier II aquatic expos ure models for a golf course turf use scenario, it is not a complete remedy for the uncertain ties involved with estimating surface water concentrations associated with the use of a pesticide on a golf course. There are sev eral aspects of pesticide use on golf course turf that may result in the model scenario underestimating surface wa ter concentrations. Golf courses are commonly built near water; many are near wetlands. Golf courses are typically designed to drain water, incorporating a mix of areas with higher slopes, depressions, and tile drainage systems. These drains rapidly transport water that infiltrates to discharge points in nearby surface water bodies. Currently, neither the Tier I nor the Tier II aquatic exposure models utilized by OPP can account for subsurface drainage as commonly occurs on golf courses. Also, the use of the GCAF assumes that the estimated surface wa ter concentrations will be reduced in equal proportion to the reduced level of acreag e treated; supporting data for this assumption are not available.
Table 7. Adjusted Tier II EDWCs and EEC’s for PCNB 1 based on golf course turf use.

Estimated drinking water concentrations acute: 159 μg/L (ppb) 2 1-in-10-years annual mean (chronic): 17.7 μg/L (ppb) 30-year mean: 9.1 μg/L (ppb) Surface water EEC’s for ecological exposure assessment acute: 69 1-in-10 Year 21-day Concentration: 50.5 (ppb) 1-in-10 Year 60-day Concentration: 37.5 (ppb) 1-in-10 Year 21-day Benthic Concentration: 28.6 (ppb)

1 Based on PCNB plus PCA for EDWC’s, and on total residues for EEC’s. 2 The actual output value from PRZM/EXAMS was 587.7 ppb for the turf use acute concentration. However, as this was greater than the aqueous solub ility of 440 ppb for PCNB, the solubility limit wa s used in the drinking water assessment. For the refinement, the adjustment factor wa s applied to the model output value (i.e., 587.7) rather than to the solubility limit.

Groundwater
Estimates for groundwater concentrations were ma de using the Tier I screening model SCI-GROW2 (Screening Concentrations in Ground Water). SCI-GRO W2 is based on a regression approach which relates the concentrations found in groundwater in Prospec tive Groundwater studies to the aerobic soil metabolism rate and soil-water partitioning properties of the chem ical. The model provides a groundwater exposure value to be used in determining the potential risk to hum an health from drinking water contaminated with the pesticide. SCI-GROW2 estimates likely groundwater concen trations if the pesticide is used at the maximum allowable rate in areas where groundwater is vulnerable to contamination. Characteristics of such vulnerable areas include high rainfall, rapidly permeable soil, and a shallow aquifer. In most cases, a large majority of the use area will have groundwater that is less vulnerable to contamination than the areas used to derive the SCI-GROW2 estimate. Input parameter values utilized for SCI-GROW2 and modeling results are presented in Table 6 along with the resultant EDWCs for the five use scenarios for which modeling was conducted; complete SCI-GROW output files can be found in APPENDIX D7 . The modeled uses were chosen because they represent the maximum single or annual use rates on the labels (excluding drench applications). As30 discussed previously in the Drinking Water EDWC’s section, the reviewer c onducted th e drinking water modeling (for both surface water and groundwater) to account for the parent compound plus PCA, a degradate considered to be a residue of con cern with regard to human health.
The data presented in the table include EDWC’s fo r the use of PCNB on bulb crops at an annual application rate of 213.4 lb a.i./A, applied in a single application. This use scenario was included in the Tier 1 screening because it represents the highest annual as well as the highest single application rate on the labels. For the purposes of comparison, th e groundwater ED WC for parent PCNB onl y (without including PCA), using the bulb application scenario. The EDWC for parent only was 13.0 ppb (vs. 30.6 ppb), indicating that the inclusion of PCA did have an effect on the groundw ater EDWC. The values for parent PCNB plus PCA are presented in Table 5

. Pentachlorophenol
It was decided by the OPP MARC committee that both pentachloroaniline (PCA) and pentachlorophenol (PCP) were both PCNB degradates of concern in water. Thus, the drinking water assessment must take into account these degradates in a ddition to the parent compound. The degradate PCA was accounted for by the recalculation of the parent ha lf-lives, as described previously. The degradate PCP, classified by EPA as a probable human carcinogen ( http://www.epa.gov/ttn/atw/hlthef/pentachl.html ), must be considered independently of PCNB and PCA. In the submitted guideline studies, pentachlorophenol (PCP) was detected as a degradate of PCNB in only two of the studies, an anaerobic soil metabolism study and a terrestrial field dissipation study. In the anaerobic so il metabolism study, PCP was first detected in the soil, at 0.28 ppm, immediately after the induction of anaerobi c conditions at 30 days, and was 0.33 ppm at 90 days (60 days post-flooding); in the water phase, PCP was 0.048 ppm at 60 days and 0.037 ppm at 90 days. [It is noted that, given current OPP modeling requirements, data from aerobic and anaerobic aquatic metabolism studies are generally considered more reliable than da ta from the anaerobic soil metabolism studies.] In the terrestrial field dissipation study in which PCP was detected, the compound was detected immediately after application at 0.022 ppm, increased with time to a maximum of 0.161 ppm by day 16, then decreased to 0.008 ppm by day 60, and was below the limit of quantif ication (LOQ; 0.005 ppm) by 120 days. The lack of detection of PCP in the second submitted anaerobic soil metabolism study and the other seven field dissipation studies does not indicate that the compound wasn’t present; it was simply not monitored in those studies. In a single aerobic soil metabolism study in which PCP was monitored, the compound was not detected.

As submitted environmental fate data on PCP (specifically, as a degradate of PCNB) are lacking, the treatment of PCP in OPP’s drinking water assessment must be qualitative in nature. The conclusions presented here were drawn mainly from informati on obtained from the published literature. Essentially, evidence that PCP is formed from PCNB during microbial degradation in soil has been found in the literature, but the weight of evidence is not substantial. Add itional data on the microbial metabolism of PCNB in both aerobic and anaerobic soil/water systems are necessary for a more complete evaluation of the environmental exposure (particularly with regard to PCP) associated with the use of PCNB.
PCP has been reported to be a “major” degrad ate of PCNB when the compound is microbially metabolized in soil (Murthy and Kaufman, 1978; Motoyama et al. , 2001). However, the term “major” was not defined in either of the publications and the second publication merely cited the first as the source of the information (as did other studies found in the literature). Thus, results of a fairly extensive literature search resulted in only one primary reference in which it was st ated that PCP is a soil metabolite of PCNB. Attempts31 to contact the study authors or their successors at the (former) USDA Pesticide Degradation Laboratory were unsuccessful.
In the first publication ( i.e. , Murthy and Kaufman, 1978), the study authors were unable to quantify the amount of PCP formed, as they discarded the aque ous portion (which accounted for 8-16% of the 56-58% of the applied that was extracted from the soil samples, for a maximum possible level of 9.28% of the applied) of their extract following an organic extraction, and were therefore unable to analyze the aqueous phase for PCP. In subsequent investigations, the study au thors were able to determine (through GLC and TLC), following acidification of the extract prior to partitioning with hexane, that PCP was the previously unidentified compound pr esent in the aqueous phase of the soil ex tract; however, they did not attempt to quantify the residues. The differences in the expe rimental conditions of the initial and subsequent investigations were not published. In a combinedsubmission from Amvac & Crompton Corporation, the registrants submitted data (based on their own laborat ory studies) which demonstrated that, had PCP been present in the initial investigations of Murthy and Ka ufman, the compound should have been detected in the organic phase in the initial experiments. They demons trated that acidification of the aqueous phase prior to partitioning with hexane would not have been necessary to extract the PCP, had it been present. Thus, they concluded that it was unlikely that PCP was actually present in the discarded aqueous phase in Murthy and Kaufman’s experiment.
In a study done in Japan, it appears that PCP was not detected in a volcanic ash soil which had been extensively treated in the past with PCNB and in wh ich the parent compound was detected in the soil at 10.10 ppm (Ohsawa et al. , 1984). However, the compound pentachloroan isole (PCAN), which is a methylated derivative of and can interconvert with PCP under certa in conditions, was detected at 0.009 ppm. (Further interpretation of this study was hindered by the fact th at much of the text was in Japanese and a translation was not available.) It has been suggested in the literature that PCAN is the product of the microbial degradation of PCP following that compound’s form ation from PCNB by soil microbes (Murthy and Kaufman, 1978; Murthy et al. , 1979). In a study of PCNB degradation by fungi, PCAN was detected (MoraTorres et al. , 1996). In a study on PCNB degradation by soil microbes native to France, neither PCP nor PCAN were observed; degradates included only PCA and PCTA (Mora-Torres et al. , 2000).
In a study of the metabolism of PCNB in anaer obic sediment in Japan, PCP was not identified as a degradate; degradates included pentachloroaniline, 2, 3,4,5-tetrachloroaniline, 3,4,5-trichloroaniline, 3,5- dichloroaniline and 3-chloroaniline (with 2-CA a nd 4-CA identified as intermediates; Susarla et al. , 1996). Tetrachloroaniline has also been identified as a metabolite of PCNB in other studies (Mora-Torres et al. , 1996).

These results indicate that there are conditions unde r which PCP can form in the environment, but that it does not form under all conditions. At this poi nt in time, we do not have sufficient information to determine what conditions favor PCP formation and which do not. Nor is there sufficient information to quantify the amount and rate of formation of PCP from PCNB when PCP is produced. Consequently, we were unable to estimate how much PCP might occur in drinking water from PCNB use. Additional data on the microbial metabolism of PCNB in both aerobic a nd anaerobic soil/water systems are necessary for a more complete evaluation of the risks associated with PCNB, particularly with regard to PCP. However, as is the case for PCB, it is likely that the contribution to the environmental loads of PCP from the use of PCNB is insignificant compared with that from the industrial uses of PCP.

Monitoring Data32 NAWQA monitoring data for PCNB and PCA in wate r are not available. Based on information contained in the USEPA’s Pesticides in Ground Water Database, A Compilation of Monitoring Studies: 1971-1991, National Summary , PCNB is not found in gr oundwater at significant leve ls or frequencies. In sampling of 1708 wells, only three detections of PCNB occurred, at a range of 0.008–0.275 μg/L. Sampled wells which did not contain measurable levels of PC NB included 459 wells in California, 71 in Maine, 649 in Minnesota, 263 in Mississippi, 10 in Oregon and 188 in Texas. However, there is no related information available with regard to whether the monitoring sit es corresponded with PCNB use sites or times of usage.
To supplement the monitoring data available from st andard sources, a literature search was conducted to obtain published information (generally post-1990 onl y) on the occurrences of PCNB and its degradates in the aquatic and terrestrial environments; informa tion on the former are included below. PCNB and its major degradates PCA and PCTA have not been detectedfrequently in North America. The presence of PCA and PCTA in the environment are most likely a result of the use of PCNB. Detections of the potential degradate PCP in the environment cannot necessarily be a ttributed to its existence as a degradate of PCNB, as PCP is extensively used as a pesticide (wood preserva tive). Similarly, detections of the degradate (and impurity in PCNB) PCB in the environment are most likely a result of its existence as a byproduct in the manufacture of other compounds or as a degradate of hexachlorobenzene (HCB), and its industrial uses.
In a groundwater monitoring study of 18 wells in three counties in California (July 1994–1995), PCNB was not detected (California EPA, 1995). In a review of multiple studies in which sampling was conducted in surface water and/or groundwater at golf courses, PCNB was monitored in surface water in an unspecified number of studies, but was not detected (Cohen et al. , 1999).
The compounds PCA, PCB and PCP were monitore d in the Mississippi River and many of its tributaries (Illinois, Missouri, Ohio, Arkansas, White, and Yazoo Rivers; Rostad et al. , 1993). PCA was detected in the surface waters at multiple locations, at concentrations of 0.018-0.055 ng/L. PCB was detected in the Mississippi River and two of its main tributaries, but was not likely a result of PCNB use. Its presence was attributed to its existence as a degradate of HCB, as suggested by the concentration profiles of the two compounds. PCP was not found in any of the surface water samples.
In summary, monitoring data on PCNB are somewh at scarce and/or incomplete information is available. As such, the data are not substantial e nough to quantitatively incorporate into the drinking water assessment. Additionally, the data have limitations in that it is not clear in most cases whether the water bodies/wells monitored correspond with or were even targeted to correspond with PCNB usage in terms of location and/or time.33 AQUATIC EXPOSURE ASSESSMENT (TIER II)
EEC’s for Ecological Risk Assessment

Table 8 presents parameter values utilized for PRZM/EXAMS modeling and the resultant EECs for the five use scenarios for which surface water modeling was conducted. The EEC’s calculated for the ecological risk assessment are based on data for total r esidues (defined here to include the parent, PCA, PCTA, PCB, PCP, PCTASO, PCTASO 2 and/or HCB, including volatiles). The EEC’s are, therefore, subject to the same uncertainties associated with the use of parent compound da ta for aqueous photodegradation and adsorption input values, as well as a potential for under estimation of the values due to model limitations, as described previously for the drinking water assessment.

Table 9 compares peak, 21-day maximum and 60-day maximum surface water concentrations to similar values for sediment concentrations pred icted using PRZM/EXAMS. While surface water concentrations decline between 45 to 77% from peak to 60-day maximums, declines ranging from 7 to 13% are estimated in benthic sediments. Thus, while expos ure may decline by as much as 77% in surface waters, sediment loads are estimated to remain relatively constant.
Based on modeling results from a provisional ve rsion of PRZM/EXAMS (PRZM9; dated November 10, 2004), for which a QA/QC has not yet been comp leted by EFED, the estimated acute surface water concentrations from turf use are predicted to decrease by 25.4% when volatilization is accounted for. Chronic ecological exposures for turf use (21- and 60-day valu es) are predicted to decrease by approximately 22% (from 186.8 ppb to 146.4 ppb) and 28% (from 138.6 ppb to 100.2 ppb), respectively, when volatilization is accounted for. Detailed information on the modeling and complete results are presented in Appendix D6.34 Table 8. PRZM/EXAMS input parameter values for PCNB (Total Residues) for the ecological risk assessment.

Parameter Value Source and/or Comments

Application Rate (lb a.i. /A/application) turf: 32.67 peanuts: 10 cabbage (cole crop): 30 potatoes: 25

cotton: 2 Reg. 5481-419 (LUIS line 1524) Reg. 5481-472 (LUIS line 1405)

Reg. 400-453 (LUIS line 360) Reg. 5481-450 (LUIS line 1503)

Reg. 400-399 (LUIS line 630)
Number of Applications turf: 2 peanuts: 1 cabbage: 1 potatoes: 1 cotton: 1 Reg. 5481-419 Reg. 5481-472 Reg. 400-453 Reg. 5481-450 Reg. 400-399
Interval Between Appli cations (days) turf: 21 peanuts: Not Applicable (NA) cabbage: NA potatoes: NA cotton: NA Reg. 5481-419

–

–

–

-- Date of First Application turf: November 15 (post-emergent) peanuts: April 15 (pre-plant) cabbage: August 15 (pre-plant) potatoes: May 20 (pre-plant) cotton: April 20 (pre-plant) Based on USDA Crop Profiles information located at http://pestdata.ncsu.

edu/cropprofiles/

Application Type, and Depth of Incorporation (cm), CAM input turf: foliar/ground spray; 0 cm; CAM = 2 peanuts: band/ground spray; 0 cm; CAM = 1 cabbage: broadcast spray; 10 cm; CAM = 4 potatoes: granular; 10 cm; CAM = 4 cotton: in-furrow spray; 0 cm; CAM = 1 Reg. 5481-419 Reg. 5481-472 Reg. 400-453 Reg. 5481-450 Reg. 400-399
Soil Partition Coefficient (K d ; mL/g) 15.5 MRID 41648201; lowest non-sand K d Aerobic Soil Metabolism Half-life (days) t 1/2 = 1124 days (total residues) MRID’s 42911902, 41384501, 41713202, 42112801; represents the 90 th percentile of the upper confidence bound on the mean of 2 half-life values
Spray Drift Fraction (ground spray) 0.01 Input parameter guidance
Application Efficiency 0.99 Input parameter guidance
Molecular Weight 295.3 g/mole Product chemistry data
Vapor Pressure 1.13 x 10 -4 Torr Product chemistry data
Henry’s Law Constant 4.42 x 10 -5 atm-m 3 -mol Product chemistry data
Solubility in Water at 25 o C (ppm) 4.4 ppm set at 10X solubility limit of 0.44 ppm based on input parameter guidance
Aerobic Aquatic Metabolism Half-life (days) t 1/2 = 2248 days (total residues) input value is 2X the aerobic soil metabolism half-life input value as in input parameter guidance
Anaerobic Aquatic Metabolism Half-life (days) t 1/2 = 2004 days (total residues) input value is two times the anaerobic soil metabolism half-life value (as in input parameter guidance); calculated using source data from MRID 41384301
Hydrolysis Half-life @ pH 7 (days) stable MRID’s 40865301, 4097260135 Aquatic Photolysis Half-life @ pH 5 (days) 1.83 MRID’s 42606201, 42606202, 42336201

Table 9. Surface water and sediment peak, 1-in-10 year 21-day and 1-in-10 year 60-day concentrations a (in ppb) of total residues (PCNB, PCA, PCTA, PCB, PCP, PCTASO, PCTASO 2 and/or HCB, including volatiles) and the percent decline in concentrations from peak to 60-day maximum.

Crop Peak Surface water conc. (ppb) Sediment conc. (ppb) 1-in-10 Year 21-day Surface water conc. (ppb) Sediment conc. (ppb) 1-in-10 Year 60-day Surface water conc. (ppb) Sediment conc. (ppb) Percent Decline from Peak to 1-in-10 Year 60-day Concentrations

Cabbage Surface water Sediment 84.1 21.0 56.1 20.8 35.8 19.9 57% 5.2%

Cotton Surface water Sediment 27.8 12.2 20.0 12.1 14.0 11.6 50% 4.9%

Peanuts Surface water Sediment 97.4 33.9 45.9 33.4 24.7 30.1 74% 11%

Potato Surface water Sediment 22.0 4.2 10.9 4.1 5.1 3.6 77% 14%

Turf Surface water Sediment 258.6 108.1 186.8 106.1 138.6 101.0 46% 6.6%

aconcentrations predicted using PRZM/EXAMS model.36 

### F BW W =

− 0 648 1 0 651 

### . * ( ) . 

### (EQ 1) TERRESTRIAL EXPOSURE ASSESSMENT
Application methods for all uses of PCNB include: drench, pre-plant broadcast, in-furrow (spray and granular), foliar spray, dip, transplant solution, ba nded, chemigation, and seed treatment. The combination of many uses and assorted application methods can poten tially result in various routes of non-target exposure to terrestrial and aquatic organisms. For this terr estrial exposure assessment, seed treatment applications and foliar applications are considered. Although PCNB is used in greenhouses, these uses do not typically result in terrestrial exposure since these uses are applied i ndoors and efforts are made to contain any off site movement of the pesticide. However, PCNB is used to treat (by drench or by use of treated soil mixtures) some greenhouse plants prior to their transfer outside to the field. This could potentially result in terrestrial exposure to birds and mammals; however, this route of exposure is not considered in this assessment.
Seed treatment applications
Birds and mammals in the field may be exposed to seed treated with pesticides by ingesting material directly with the diet. They also may be exposed by other routes, such as incidental ingestion of contaminated soil, dermal contact with treated seed surfaces and soil during activities in the treated areas, preening activities, inhalation of pesticide vapor and contaminated particulate, and ingestion of drinking water contaminated with pesticide. For estimating this rout e of exposure in this assessment, only ingestion of the treated seed was considered.

Terrestrial estimated environmental concentrations (EEC) and acute risk quotient values have been calculated in two different ways for the purposes of assessing risk from PCNB-treated seeds. The first way looks at the dietary dose assuming that an organism h as been eating only treated seed. This approach uses the acute oral toxicity for the toxicity endpoint (LD 50 ). The second method also uses the acute oral dose for toxicity (LD 50 ) but compares it to the available concentration of pesticide on the basis of pesticide per square foot.
In the process of assessing PCNB seed treatments, it was necessary to estimate the maximum likely seeding rates for a number of crops for use in the risk assessment. This informati on has been collected for other seed treatment pesticides, and in order to en sure consistency across Division products, these maximum estimated seeding rates are shown Table 10

. Avian Exposure
The first method of assessing exposure to treated seeds, was used to assess risk to the smallest birds that eat seeds, which weigh about 20 g. Small birds tend to eat more per unit body weight, so they will be the most vulnerable. Exposure is estimated from the concentration of PCNB on treated seed. For example, the maximum application rate to cotton (14.5 fl oz./cwt seed) is equivalent to 2265 mg a.i. kg -1 of seed. Using daily food intake as estimated by Nagy (1987) ( EQ 1 ), a 20-g bird will consume about 5.06 g of food (wet weight) based on the allometric equation:37 

### Adj.LD = LD 50 50 ( -1) 

### ( )

AW TW a 

### (EQ 2) Table 10. Seeding and PCNB application rates in pounds per acre for selected crops in the United States

Crop Maximum Seeding Rate (lbs seed/acre) a RTU-PCNB Application Rate

(fl oz ai/cwt) b Maximum Application Rate (lbs a.i/acre) c Barley 100 7.5 0.1171

Bean 65 3 0.0750

Corn 25 3 0.0117

Cotton 18 14.5 0.0408

Oats 128 11 0.2199

Pea 180 6 0.1687

Peanuts 135 3.5 0.0738

Rice 160 8.9 0.2224 Sorghum 8 1.75 0.0022 Soybeans 100 6 0.0937 Sugar beets 8 10.75 0.0134

Wheat 135 3 0.0633

a Seeding rates reported here are those used in some past assessm ents by OPP and which were obtained from crop profiles or throug h discussions with various pesticide registrants. Maximum seeding rates were us ed from various crop profiles (these profiles can be found at http://pestdata.ncsu.edu/croppr ofiles/cplist.cfm?org=crop ). When the registrant-submitted value was hi gher than those found in the crop profiles, they were used preferentially.
b Label rates

c Maximum application rate of PCNB (lbs ai/acre) =( Maximum seed ing rate (lbs seed/acre) * Maximum seed application rate (lbs ai /100 lbs seed))/100 where F is the food intake in grams of fresh weight per day, BW is the body mass (wet weight) of the organism, and W is the mass fraction of water in the food. For this assessment W is assumed to be 0.1. This results in a dose of PCNB of 573 mg a.i. day -1 (5.06 g seed day -1 * 0.001 kg g -1 * 2265 mg a.i. kg seed -1 ÷ 0.02 kg). In addition, extrapolations from one bird to another need to consider differences in the scaling of toxicity for differences in body weight. The LD 50 can be adjusted for body weight based on the formula ( EQ 2 ) recommended by Mineau et al. 1996:

where adjusted LD 50 is the median 50% lethal dose for the species being assessed, LD 50 is the median lethal dose in the test organism, AW is the body weight of the assessed organism, TW is the body weight for the test organism, and a is the slope of the regression line for estimating the assessed species LD 50 from the test species LD 50 (EFED default value of 1.15). In the case of assessing a small songbird, 20 g is a suitable value for AW. The test organism is a sub-adult bobwhite quail which weighs about 200 g. With a test LD 50 of greater than 2250 mg kg -1 , the adjusted LD 50 is greater than 1593 mg kg -1 . A summary of risk quotients calculated with this method can be found in the ecological hazard assessment section of this document.38 

### Adj.LD = LD 50 50 

### ( ) (. ) 

### TW AW 0 25 

### (EQ 4) 

### F BW W =

− 0 621 1 0 564 

### . * ( ) . 

### (EQ 3) For the second method of assessing risk due to treated seed, it is assumed that 100% of the seed is available for consumption. This is reasonable as the seed is small and is generally not planted deeply (<2 inches), although seeding depths of up to 2- to 3-inches and 3- to 4-inches may be used for crops such as peanuts and potatoes, respectively. Seed can either be planted by drill, or broadcast followed by a drag chain. With either method it will be near the surface and ge nerally available to wildlife. The amount of PCNB available is then the cotton seed application rate of 18 lbs of seed acre -1 (0.0408 lbs a.i./acre). This is equivalent to 0.43 mg ft -2 . The adjusted LD 50 (1593 mg•kg -1 ) is then multiplied by the weight of the assessed bird (0.020 kg) to yield the lethal dose of PCNB (31.9 mg) as above for cotton the risk quotient (0.43 ÷ 31.9) for this method is 0.01. Mammalian Exposure
A similar approach to that used for birds in calculating exposure was used for mammals. Equations used for calculating the daily food intake and the ad justed toxicity value for a 35 g mammal are provided below (Nagy 1987; USEPA 1995). The analysis assumed that small mammals would weigh 35 g and would consume roughly 5.13 g (wet wgt.) of food per day ( EQ 3 ). The estimated dose of PCNB in cotton would be 332 mg a.i. day -1
, i.e. , (5.13 g seed day -1 * 0.001 kg g -1 * 2265 mg a.i. kg -1 ÷ 0.035 kg). Also, similar to the approach used for birds, the LD 50 was adjusted to reflect the differential in toxicity to a 35 g mammal versus the rough average weight (350 g) of the rats used in the acute oral toxicity study; the adjusted LD 50 ( EQ 4 ) was determined to be 8980 mg kg -1

.

A summary of the risk quotients calculated using both methods can be found in the ecological hazard assessment section in this document.
Foliar Applications and Residues
Terrestrial exposure was also evaluated using EEC’s generated from a spreadsheet-based model (ELL-FATE) that calculates the decay of a chemi cal applied to foliar surfaces for single or multiple applications. The model uses the same principle as the batch code models FATE and TERREEC for calculation of terrestrial estimated exposure concen trations (TEEC) on plant surfaces following application. Further explanation of the model is presented in APPENDIX F

. The terrestrial exposure assessment is based on the methods of Hoerger and Kenaga (1972) as modified by Fletcher et al. (1994). Terrestrial estimated environmental concentrations (EECs) for nongranular formulations ( Table 11 ) were derived for major crops (col e crops, cotton, and turf) using current application rates and intervals between applications . Uncertainties in the terrestrial EECs are primarily associated with a lack of data on interception and sub sequent dissipation from foliar surfaces. When data are absent, as in this case, EFED assumes a 35-day foliar dissi pation half life, based on the work of Willis and McDowell (1987).
For pesticides applied as a nongranular product ( e.g. , liquid, dust), the estimated environmental concentrations (EECs) on food items followi ng product application are compared to LC 50 values to assess risk. Uses and associated application rates modele d for terrestrial exposure assessments are presented in39 Table 11a . The predicted maximum and mean residues of PCNB that may be expected to occur on selected avian or mammalian food items immediately following a pplication (at the maximum annual or seasonal label rate) for cole crops, peanuts, potatoes, and turf are presented in Table 11b . Although cotton is a major use of PCNB, it is not modeled for terrestrial exposure pur poses since the registrants have provided information indicating that there are no foliar uses of PCNB; fo r cotton, PCNB is applied to the ground and is then incorporated.
Table 11a. Selected uses and maximum PCNB app lication rates modeled for terrestrial exposure assessment.

Crop Rate (lb ai/A) No. of Applic. (interval) Timing Formulation Application Type Notes

cabbage 1 22.5 1 postplant wettable powder soil band trt. (sprayer) applic. is to soil, not foliage

peanuts 3 10 1 bloom emulsifiable concentrate chemigation (sprinkler irrigation) SLN (TX)

5 2 (30 d) bloom emulsifiable concentrate chemigation (sprinkler irrigation) SLN (TX)

3.2475 x 3

(total of 9.9975) 3 (interval not reported) postemergence wettable powder spray (sprayer)

potatoes 4 5 (single applic.); 20 total applic. no. of applic. not reported; interval not

reported foliar flowable concentrate chemigation (sprinkler irrigation) SLN (ID, OR, WA)

turf 32.67 2 (21 d) foliar40 Table 11b. Estimated environmental concentrat ions on avian and mammalian food items (ppm) following label specified applications of PCNB to cole crops, peanuts, potatoes, and turf.

Crop Application Rate lbs. a.i./A (# app / interval, days) Food Items Predicted Maximum Residue EEC (ppm) 1 Predicted Mean Residue EEC (ppm) 2

Cole crops 22.5
(1 / NA) Short grass 5400 1913 Tall grass 2475 810 Broadleaf plants/small insects 3038 1013 Fruits, pods, seeds, and large insects 338 158

Peanuts Special Local Needs (SLN)– TX

10
(1 / NA) Short grass 2400 850 Tall grass 1100 360 Broadleaf plants/small insects 1350 450 Fruits, pods, seeds, and large insects 150 70

SLN– TX

5
(2 / 30) Short grass 1862 660 Tall grass 854 279 Broadleaf plants/small insects 1048 349 Fruits, pods, seeds, and large insects 116 54

3.2
(3 / 7) Short grass 2049 726 Tall grass 909 307 Broadleaf plants/small insects 1152 384 Fruits, pods, seeds, and large insects 128 60

Potato SLN– ID, OR, WA

5
(4 / 7) Short grass 3946 1397 Tall grass 1808 592 Broadleaf plants/small insects 2220 740 Fruits, pods, seeds, and large insects 247 115

Turf SLN– CA, OR, WA

43.56
(2 / 7) Short grass 19555 6926 Tall grass 8963 2933 Broadleaf plants/small insects 11000 3667 Fruits, pods, seeds, and large insects 1222 570

1 Predicted maximum and mean residues are based on Ho erger and Kenaga (1972) as modified by Fletcher et al. (1994).
2 Predicted mean residues from Fletcher et al.: Short grass = 85; Tall grass = 36; Broadleaf plants / insects = 45; and Seeds / fruits = 741 ECOLOGICAL EFFECTS CHARACTERIZATION

APPENDIX E discusses the 34 ecological toxicology studies submitted by the registrant for consideration: 76% were classified as core (accepta ble) and having provided useful information toward fulfilling the required guideline data. The remain ing (24%) studies were classified as supplemental. Although ecological effects were documented over a broad range of concentrations, toxicity estimates for species assemblages, e.g., freshwater fish, were tightly clustered and thus consistent. Toxicity testing reported in this section does not represent all species of bird, mammal, or aquatic organism. Only a few surrogate species for both freshwater fish and birds are used to represent all freshwater fish (2000+) and bird (680+) species in the United States. For mammals, acute studies are usually limited to Norway rat or the house mouse. Estuarine/marine testing is usually limite d to a crustacean, a mollusk, and a fish. Also, neither reptiles nor amphibians are tested. The assessment of risk or hazard makes the assumption that avian and reptilian toxicities are similar. The same assump tion is used for fish and amphibians.
PCNB is practically non-toxic to honey bees, bird s and mammals; and highly toxic to freshwater fish and invertebrates; and very highly toxic to estuarine/marine fish and invertebrates. Table 12 provides a summary of the most sensitive ecological toxicity endpoints used in the hazard assessment of terrestrial animals and Table 13 summarizes the most sensitive endpoints used in the risk assessment of aquatic animals. No registrant-submitted data were available to assess the toxicity of PCNB to either terrestrial or aquatic plants and the chronic toxicity to estuarine/marine i nvertebrates. A more detailed discussion of the ecological toxicity studies that went into this assessment can be found in APPENDIX E

. Table 12. Summary of acute and chronic toxici ty data for terrestrial organisms exposed to pentachloronitrobenzene.

Species Acute Toxicity Chronic Toxicity

LD 50 (ppm) Acute Oral Toxicity (MRID) 5-day LC 50 (ppm) Subacute Dietary Toxicity (MRID) NOEC/LOEC (ppm) (MRID) Affected Endpoints

Northern bobwhite quail Colinus virginianus >2250 practically nontoxic (406180-01) >54,000 practically nontoxic (406526-02) 600/1200 (413328-01) reproduction

Mallard duck Anas platyrhynchos -- -- >54,000 practically nontoxic (406526--03) 600/1200 (413328-02) growth

Honey bee Apis meliferus >0.1 (mg/bee contact) practically nontoxic (405061-02) -- -- -- --

Laboratory rat Rattus norvegicus >5050 practically nontoxic (414431-01) -- -- 200/2000 (434693-03)

PCNB was practically non-toxic to bobwhite quail ( Colinus virginianus ) and rats ( Rattus norvegicus ) on an acute exposure basis and practically non-toxic to the mallard duck ( Anas platyrhynchos ) and bobwhite quail ( Colinus virginianus ) on a subacute dietary basis. Chronic toxicity data on ducks (NOEC = 600 ppm) revealed that reproduction and growth were the most sensitive endpoints. Chronic toxicity testing on rats (NOEC = 200 ppm) resulted in no compound-related re productive effects; however, liver and thyroid hypertrophy were noted.42 Table 13. Summary of acute and chronic aquatic toxicity estimates using pentachloronitrobenzene.

Species Acute Toxicity Chronic Toxicity

96-hr LC 50

(mg/L) 48-hr EC 50 (mg/L) Acute Toxicity (MRID) NOEC / LOEC (mg/L) Affected Endpoints (MRID)

Rainbow trout Oncorhynchus mykiss (TGAI) 0.32 -- highly toxic (409927-01) 0.013 /0.032 growth (416634-01)

Bluegill sunfish Lepomis macrochirus (TGAI) 0.10 -- highly toxic (406180-04) -- --

Rainbow trout Oncorhynchus mykiss (formulated product) 0.31 -- highly toxic (410608-02) -- --

Bluegill sunfish Lepomis macrochirus (formulated product) 0.24 -- highly toxic (410308-01) -- --

Water flea Daphnia magna -- 0.77 highly toxic (114167) 0.018 /0.030 reproduction (413213-01)
Sheepshead minnow Cyprinodon variegatus 7.9 -- moderately toxic (408829-03) -- --

Eastern oyster Crassostrea virginica 0.023 -- very highly toxic (408829-02) -- --
Mysid shrimp Mysidopsis bahia 0.012 -- very highly toxic (408323-01) -- –
Acute aquatic toxicity estimates ranged from 0. 012 to 7.9 mg/L for PCNB. Estuarine/marine organisms generally were more sensitive to the effect s of PCNB than their freshwater counterparts. The chronic toxicity of PCNB was 0.013 mg/L to rainbow trout ( Oncorhynchus mykiss ) and 0.018 mg/L to the water flea ( Daphnia magna ). The most sensitive endpoints were reduced growth and reproduction.
Although open literature indicates that some of the metabolites (pentachloroaniline, PCA; pentachlorothioanisole, PCTA; pentachlorobenzene, PCB; PCTA sulfoxide; PCTA sulfone; and pentachlorophenol, PCP) of PCNB are toxic, OPP has r eceived no specific toxicity data from the registrant(s) with which to evaluate the toxicity of those meta bolites. Thus, OPP utilized the ECOTOX (Ecotoxicology Database System) on-line database and also conducted an extensive open literature review in an attempt to supplement the registrant submitted data. ECOTOX is a comprehensive computer-based system that provides single chemical toxic effect data for aquatic life, terrestrial plants and terrestrial wildlife derived predominately from peer-reviewed literature. The literature relevant to the exposure and toxic effects of PCNB and the metabolites was collected, reviewed and ev aluated for inclusion into this chapter. Citations and abstracts were obtained by searching the following commercial or publicly available databases: TOXLINE, MEDLINE, BIOSIS previews, AGRICOL A, and AQUIRE, as well as, Dissertation Abstracts. For a more in-depth discussion of the ECOTOX on-line database, see http://www.epa.gov/ecotox/

. The terrestrial ECOTOX output of selected speci es for PCNB and three of the metabolites of toxicological concern, PCA, PCB, and PCP, is shown in Table 14 . A total of 782 terrestrial records were found in the ECOTOX on-line database for PCNB, PCA, PCB, and PCP, covering both plant and animals listings. The highest percentage of records (93.73% ) contained in the database output were found for PCP;43 thus, there were very limited data on parent PCNB. PCNB, PCA, and PCB accounted for 1.92%, 1.53%, and 2.81%, respectively, of the database output. The diffe rence in proportion in the output among the parent and 3 metabolites is probably due to PCP coming from the multiple industrial sources of PCP and therefore a broader awareness among researchers of the ecotoxicological concerns. While toxicity information did not often overlap for a given species among the parent and three metabolites for the terrestrial database output, some of the data available did suggest poten tial trends in toxicity among these compounds ( Table 14 ). Additionally, the selected records in Table 14 only represent a small fraction of the species represented in the total ECOTOX output for the PCNB metabolites.
Table 14. Summary of selected acute terrestrial toxicities for pentachloronitrobenzene, pentachloroaniline, pentachlorobenzene, and pent achlorophenol listed in the ECOTOX on-line database.

Scientific Name (Common Name) Acute Toxicity LC 50 (ECOTOX record number)

PCNB PCA PCB PCP

Mallard duck Anas platyrhynchos >5000 ppm (344)* ND ND 3763 ppm (344)*
Bobwhite quail Colinus virginianus >5000 ppm (344)* ND ND 5581 ppm (344)*
Honeybee Apis mellifera 0.1 μg/bee (344)* ND ND >48 μg/bee (344)*

Lettuce Lactuca sativa ND 471 (growth) (56443) 56 mg/kg (growth) (56443) 2.7 mg/kg (growth) (56443)

Earthworms Eisenia andrei ND ND

Red marsh worm Lumbricus rubellus ND ND

*ECOTOX record 344 represents registra nt-submitted data and not open literature. The on-line ECOTOX output for PCNB was rather limited, containing just 15 records. Six of those studies were field studies conducted using Kentucky bluegrass ( Poa pratensis) (4 records) and potatoes ( Solanum tuberosum ) (2 records). Of the remaining nine record s, there were two studies that examined the germination EC 50 effects of PCNB on Chinese radish ( Raphanus sativus ) and shattercane grass ( Sorghum bicolor drummondii ) and were unclear as to the effect of PCNB . The remaining seven records were for the honeybee ( Apis mellifera) , bobwhite quail ( Colinus virginianus ) and the mallard duck ( Anas platyrhynchos) and were already submitted to OPP in support of the registration of PCNB.
Like many other fungicides ), PCNB is toxic to earthworms. Studies not found in ECOTOX on-line, but in other literature searches show earthworms (Eisenia fetida ) exposed to soil containing 144 μg PCNB/cm 3 soil did not reproduce and died within 29 days of treatment (WHO, 1984). Another study found that there was no reproduction by worms and significant mortality in soil treated with PCNB (Roark et al. , 1979). Both PCB and PCP also showed toxicity to earthworms. PCB toxicities ranged from 134 to 201 mg/kg soil, while PCP toxicities ranged from 84 to 362 mg/kg soil.
Tests on both the mallard duck and bobwhite quail s howed that PCNB was practically non-toxic to birds. No mortalities were observed in studies with ducks and quail, but anorexia and significantly reduced weight gain compared to controls were reported in the highest treatment groups. Further literature searches44 found a study that described tests on white leghorn chic kens had similar results to the OPP-submitted studies (WHO, 1984). However, at the highest dose level ( 1000 mg/kg diet), onset of egg production was delayed by one month and the number of ch icks hatched from fertile eggs si gnificantly decreased from 91% in the controls to 69% in the treated birds. Additionally, body weight gains were significantly lower in hens fed at the highest dose rate.
The aquatic ECOTOX output of selected species for PCNB and three of the metabolites of toxicological concern, PCA, PCB, and PCP, is shown in Table 15 . There were a total of 2073 records contained in the database output for the parent and the three metabolites. As in the terrestrial output, PCP records made up the majority (88.71 %). PCNB, PCA, and PCB accounted for 3.04%, 0.60%, and 8.15%, respectively, of the database output. Additionally, as w ith the terrestrial output, toxicity information did not often overlap for a given species among the parent and three metabolites for the aquatic database output. Furthermore, the selected records in Table 15 only represent a small fraction of the species represented in the total on-line ECOTOX output.
Table 15. Summary of selected acute aquatic toxicities for pentachloronitrobenzene, pentachloroaniline, pentachlorobenzene, and pent achlorophenol listed in the ECOTOX on-line database.

Scientific Name (Common Name) Acute Toxicity LC 50 ECOTOX record number

PCNB PCA PCB PCP
Lepomis macrochirus (Bluegill sunfish) 100 μg/l (344)* ND 250 μg/l (5590) 115 μg/l (10775)
Pimephales promelas (Fathead minnow) ND ND 247 μg/l (14339) 95 μg/l (10679)
Oncorhynchus mykiss (Rainbow trout) 320 μg/l (344)* ND 190 μg/l (16044) 115 μg/l (6797)
Cyprinodon variegatus (Sheepshead minnow) 7900 μg/l (344)* ND 800 μg/l (10366) 442 μg/l (2080)

Danio rerio (Zebra danio) ND 56 μg/l (3279) 140 μg/l (3279) 400 μg/l (5938)

Poecilia reticulata (Guppy) ND ND 159.5 μg/l (2422) 204 μg/l (11344)

Carassius auratus (Goldfish) ND ND ND 117 μg/l (10775) *ECOTOX record 344 represents registra nt-submitted data and not open literature. The ECOTOX on-line database for aquatic organisms was not as limited as for terrestrial organisms; however, only 63 records were found in the PCNB out put, of which 16 records were already submitted to OPP in support of the registration of PCNB. Anothe r 26 records were bioconcentration studies to various fish and green algal species. Sixteen r ecords were neither bioaccumulation or LC 50 / EC 50 tests, although they contained toxicity endpoints of an unspecified nature. Finally, there were five records that described LC 50 information for carp.
The toxicity information on PCNB and its metabolites revealed that there is a potential for negative impacts to aquatic organisms. A study with zebrafish (van Leeuwen et al. , 1990) suggests that PCA may adversely affect development of fish exposed during th e early life stages of these organisms. The sand shrimp45 ( Crangon septemspinosa ) exposed to PCA for 96 hours exhibited an LC 50 = 300 μg/l (McLeese et al. , 1979). Because of this apparent aquatic toxicity and lack of submitted data on this chem ical, additional data on the acute and chronic toxicity of PCA to aquatic orga nisms would reduce uncertain ties in this risk assessment.
Growth, development, an d reproduction were impaired in aqua tic vertebrates and invertebrates exposed to sublethal concentrations of PCB (van Leeuwen et al., 1990). Brine shrimp ( Artemia salina ) exposed to PCB in a 24-hour experiment had an LD 50 = 1.5 mmol/m 3 (Abernethy et al. , 1986). Opossum shrimp ( Americamysis bahia ) exhibited an LC 50 = 160 μg/l in a 96-hour exposure experiment (U.S. EPA, 1978). Tests on chironomids resulted in a 48-hour LC 50 = 230 μg/l (Roghair et al. , 1994). Acute toxicity values for PCB show that the LC 50 values for several fish species (guppies, bluegills, fathead minnows, sheepshead minnows) occurred in the 100 to 800 μg/l range (highly toxic).
PCP also appears to be acutely toxic to various sp ecies of aquatic vertebrates and invertebrates. LC 50 values of PCP in several copepod species ranged fro m approximately 50 to 230 μg/l (Willis, 1999). Early larval stage copepods were similarly sensitiv e to PCP as were the adults. The amphipods, Chaetogammarus marinus and Crangonyx pseudogracilis, had LC 50 values of 450 μg/l and 139 μg /l, respectively (Spehar et al. , 1985; Adema et al. , 1981). The marine species flounder (Platichthys flesus ), sole ( Solea solea ) and sheepshead minnow ( Cyprinodon variegatus ) exhibited LC 50 values in the range of 450 to 770 μg/l, while those for Southern leopard frogs and Boreal toad tadpoles ranged from 140 to 370 μg/l (Bridges et al , 2002). LC 50 values for the Atlantic salmon ( Salmo salar) ranged from 58 to 500 μg/l (Burridge et al. , 1990 and U.S. EPA Office of Pesticide Programs, 2000).
Adverse effects on growth and development, repr oduction and behavior have been reported in aquatic organisms exposed to sublethal concentrations of PCP (Sais et al. , 1993, 1994). Development was also adversely affected in anuran amphibi ans (frogs/toads) exposed to sublethal concentrations of PCP with effects ranging from inhibited tail resorption (NOEC = 5.0 μg /l, LOEC = 10.0 μg/l, Fort and Stover, 1997) to underdeveloped gills and axial morphogenesis (LOEC = 15 μg/l), neural tube occlusion and edema (LOEC = 150 μg/l), inhibition of cephalization (LOEC = 300 μg /l) and significant developmental delays (LOEC = 1500 μg/l, Venegas et al. , 1993).
Plant Toxicity
No plant toxicity data were available for PCNB or many of its degradates. Estimates of aquatic plant toxicity for chlorinated benzenes ( Table 16 ) were provided through the ASTER model. ASTER (AS sessment T ools for the E valuation of R isk) was developed by the U. S. EPA Mid-Continent Ecology Division, Duluth, MN (MED-Duluth) to assist regul ators in performing ecological risk assessments. ASTER is an integration of the AQUIRE (AQUatic toxicity In formation REtrieval) toxic effects database and the QSAR (Quantitative Structure Activity Relationships) sy stem, a structure activity based expert system. When empirical data are not available mechanistically-based predictive models are used to estimate ecotoxicology endpoints, chemical properties biodegradation, and e nvironmental partitioning. AS TER is designed to provide high quality data for discrete chemicals, when av ailable in the associated databases and QSAR-based estimates when data are lacking. The QSAR system includes a database of physicochemical properties such as melting point, boiling point, vapor pressure, and water solubility as well as more than 56,000 molecular structures stored as SMILES (Simplified Molecular InputLine Entry System) strings for specific chemicals. For a more complete understanding of the model, please see http://www.epa.gov/med/databases/aster.htm.

Estimated EC 50 values for freshwater nonvascular plants s uggest that chlorinated benzene toxicity increases with the number of chlorines.46 Table 16. ASTER a model-generated 96-hr EC 50 estimates in mg/L (ppm) for selected chlorinated benzene compounds.

Species Chemical measurement endpoint 96-hr EC 50 mg/L
Green algae Selenastrium capricornutum chlorobenzene chlorophyll a 232

Green algae Selenastrium capricornutum chlorobenzene cell numbers 242

Green algae Selenastrium capricornutum 1, 2, 4-trichlorobenzene chlorophyll a 35.3

Green algae Selenastrium capricornutum 1, 2, 4-trichlorobenzene cell numbers 36.7

Green algae Selenastrium capricornutum 1, 2, 3, 5-tetrachlorobenzene chlorophyll a 17.2

Green algae Selenastrium capricornutum 1, 2, 3, 5-tetrachlorobenzene cell numbers) 17.7

Green algae Selenastrium capricornutum 1, 2, 4, 5-tetrachlorobenzene chlorophyll a 52.9

Green algae Selenastrium capricornutum 1, 2, 4, 5-tetrachlorobenzene cell numbers 46.8

Green algae Selenastrium capricornutum pentachlorobenzene chlorophyll a 6.78

Green algae Selenastrium capricornutum pentachlorobenzene cell numbers 6.63

aASTER (ASsessment Tools for the Evaluation of Risk) was devel oped by the U.S. EPA Mid-Continent Ecology Division, Duluth, MN47 RISK CHARACTERIZATION

Risk Estimation
To evaluate the potential risk to nontarget organi sms from the use of PCNB products, risk quotients (RQs) are calculated from the ratio of estimated envir onmental concentrations (EECs) to ecotoxicity values. RQs are then compared to levels of concern (LOC’s) used by OPP to indicate pot ential risk to nontarget organisms and the need to consider regulatory action (see APPENDIX G for more discussion). When available, field studies and incident data were compared to risk estimates for PCNB.
Nontarget Terrestrial Animals
The estimated environmental concentration (EEC) values used for terrestrial exposure are derived from the Kenaga nomograph, as modified by Fletcher et al. (1994), based on a large set of actual field residue data. The upper limit values from the nomograph represent the 95th percentile of residue values from actual field measurements (Hoerger and Kenega, 1972). The Fletcher et al. (1994) modifications to the Kenaga nomograph are based on measured field residues from 249 published research papers, including information on 118 species of plants, 121 pesticides, and 17 chemical classes. These modifications represent the 95 th percentile of the expanded data set. Risk quotients are based on the most sensitive LC 50 and NOAEC for birds (in this instance, bobwhite quail) and LD 50 for mammals (based on lab rat studies).
Acute and chronic risk quotients were calcu lated following the procedure outlined in APPENDIX G and were then compared to LOC’s. Acute restri cted use and acute risk to endangered species LOC’s (RQ $ 0.2) are exceeded for birds ( Table 17 ) foraging on short grass (RQ <0.36) and broadleaf plants/insects (RQ<0.2) at current application rates for turf wh ile the acute risk to endangered species LOC (RQ $ 0.1) is exceeded for birds feeding on tall grasses following applica tion to turf. The application rate on cole crops (cabbage) also exceeded the acute risk to endangered species LOC. Importantly, the LC 50 for Bobwhite quail used in the RQ calculations was greater than the highest concentration tested ( i.e. , LC 50 >54,000 ppm); therefore, all acute RQ values are l ess than the calculated value. For th is reason, OPP considers the likelihood of acute mortality to birds to be low for all of the modeled uses.
The chronic risk LOC (RQ $ 1.0) for birds, based on maximum estimated environmental concentrations, is exceeded (RQ range: 0.19 – 33) for all of the crops modeled. The single largest market for PCNB, as of 2000, is for turf (49%), which also produced the highest range of chronic RQs (2 – 33) with the chronic risk LOC exceeded across all forage categories. Aggregated, cole crops, peanuts, and potatoes also account for a use of PCNB; these various scenarios all produced RQs that ranged from 0.19 to 9. Only the “fruits, pods, seeds, and large insect” category for these crops had RQs below the chronic risk LOC. Estimated mean residue values are roughly 60% less than maximum estimated concentrations used in calculating chronic RQ’s; chronic RQ’s based on mean residues would decrease by roughly the same percent.
Acute mammalian risk LOC’s are exceeded (RQ range: 0.01 – 3.7) in at least one category for all major crops modeled ( Table 18 ). As with the birds, the turf scen ario produced the highest RQ values, followed by cole crops, potatoes, and peanuts. Th e mammalian RQ values were calculated using a rat LD 50 of greater than 5050 mg/kg bw (ppm), so all acute mammalian RQs are potentially less than the calculated value. As with the avian acute RQs, OPP consider s the likelihood of mammalian acute mortality to be low for all of the modeled uses.48 Chronic mammalian risk LOC’s are exceeded (RQ range: 1 – 1858) for all crops modeled ( Table 19 ) and on all forage items except seeds; for larger-si zed (1000 g) mammals, chronic RQ values were below the chronic risk LOC at the maximum application rate s for cole crops, peanuts and potatoes. While the chronic LOC’s are exceeded for the majority of crops modeled and food items evaluated, the highest RQs are associated with crops receiving the majority of th e annual PCNB applications in the United States.
Table 17. Avian acute and chronic risk quotients for selected uses of nongra nular products of PCNB based on a bobwhite quail LC 50 of >54,000 mg/kg diet ( ppm) and NOAEC of 600 mg/kg diet ( ppm).

Use/App. Method Application Rate lbs. a.i./A (# app / interval, days) Food Items Maximum EEC (mg/kg) e Mean EEC (mg/kg) e Acute RQ (EEC/LC 50 ) Chronic RQ (EEC/ NOAEC)

Cabbage 22.5
(1 / NA) Short grass 5400 1913 <0.10 d 9.0 e
Tall grass 2475 810 <0.05 4.1 e
Broadleaf plants/small insects 3038 1013 <0.06 5.1 e
Fruits, pods, seeds, and large insects 338 158 <0.01 0.56

Peanuts SLN (TX)

10
(1 / NA) Short grass 2400 850 <0.04 4.0 e Tall grass 1100 360 <0.02 1.8 e Broadleaf plants/small insects 1350 450 <0.03 2.3 e Fruits, pods, seeds, and large insects 150 70 <0.01 0.25

SLN (TX)

5
(2 / 30) Short grass 1862 660 <0.03 3.1 e Tall grass 854 279 <0.02 1.4 e Broadleaf plants/small insects 1048 349 <0.02 1.8 e Fruits, pods, seeds, and large insects 116 54 <0.01 0.19

3.2475
(3 / 7) Short grass 2049 726 <0.04 3.4 e Tall grass 939 307 <0.02 1.6 e Broadleaf plants/small insects 1152 384 <0.02 1.9 e Fruits, pods, seeds, and large insects 128 60 <0.01 0.21

Potato SLN (ID,OR,WA)

5
(4 / 7) Short grass 3946 1397 <0.07 6.6 e Tall grass 1808 592 <0.03 3.0 e Broadleaf plants/small insects 2220 740 <0.04 3.7 e Fruits, pods, seeds, and large insects 247 115 <0.01 0.41

Turf SLN (CA, OR, WA)

43.56
(2 / 7) Short grass 19555 6926 <0.36 c 33 e
Tall grass 8963 2933 <0.17 d 15 e
Broadleaf plants/small insects 11000 3667 <0.20 c 18 e
Fruits, pods, seeds, and large insects 1222 570 <0.02 2.0 e49 aestimated environmental concentrations predicted using 1 st -order degradation model based on foliar dissipation.
b exceeds acute risk (RQ $ 0.5), restricted use (RQ $ 0.2) and endangered species level of concern (RQ $ 0.1)

c exceeds restricted use (RQ $ 0.2) and endangered species level of concern (RQ $ 0.1)
d exceeds acute endangered species level of concern (RQ $ 0.1)

e exceeds chronic risk level of concern (RQ $ 1.0)
Table 18. Acute RQ values for small (15-g), interm ediate (35-g) and large (1,000-g) mammals feeding on short or tall grass, broadleaf plants/small in sects, fruits/pods/large insects and seeds exposed to PCNB following single and multiple applications based on a rat LD 50 >5,050 mg/kg bw (ppm).

Use/App. Method Application Rate lbs. a.i./A (# app / interval, days) Food Items Maximum EEC (mg/kg) d Acute Mammalian RQ
Body weight (g)

15 35 1000

Cabbage 22.5
(1 / NA) Short grass 5400 <1.0 a <0.71 a <0.16 c
Tall grass 2475 <0.47 b <0.32 b <0.07
Broadleaf plants/small insects 3038 <0.57 a <0.40 b <0.09
Fruits, pods, and large insects 338 <0.06 <0.04 <0.01
Seeds (granivores) 338 <0.01 <0.01 <0.01

Peanuts SLN (TX)

10
(1 / NA) Short grass 2400 <0.45 b <0.31 b <0.07 Tall grass 1100 <0.21 b <0.14 c <0.03 Broadleaf plants/small insects 1350 <0.25 b <0.18 c <0.04 Fruits, pods, and large insects 150 <0.03 <0.02 <0.01 Seeds (granivores) 150 <0.01 <0.01 <0.01 SLN (TX)

5
(2 / 30) Short grass 1862 <0.35 b <0.24 b <0.06 Tall grass 854 <0.16 c <0.11 c <0.03 Broadleaf plants/small insects 1048 <0.20 b <0.14 c <0.03 Fruits, pods, and large insects 116 <0.02 <0.02 <0.01 Seeds (granivores) 116 <0.01 <0.01 <0.01

3.2475
(3 / 7) Short grass 2049 <0.39 b <0.27 b <0.06 Tall grass 939 <0.18 c <0.12 c <0.03 Broadleaf plants/small insects 1152 <0.22 b <0.15 c <0.03 Fruits, pods, and large insects 128 <0.02 <0.02 <0.01 Seeds (granivores) 128 <0.01 <0.01 <0.01

Potato SLN (ID,OR,WA)

5
(4 / 7) Short grass 3946 <0.74 a <0.52 a <0.12 c Tall grass 1808 <0.34 b <0.24 b <0.05 Broadleaf plants/small insects 2220 <0.42 b <0.29 b <0.07 Fruits, pods, seeds, and large insects 247 <0.05 <0.03 <0.01Use/App. Method Application Rate lbs. a.i./A (# app / interval, days) Food Items Maximum EEC (mg/kg) d Acute Mammalian RQ
Body weight (g)

15 35 1000

50 Seeds (granivores) 247 <0.01 <0.01 <0.01

Turf SLN (CA, OR, WA)

43.56
(2 / 7) Short grass 19555 <3.7 a <2.6 a <0.58 a Tall grass 8963 <1.7 a <1.2 a <0.27 b Broadleaf plants/small insects 11000 <2.1 a <1.4 a <0.33 b Fruits, pods, and large insects 1222 <0.23 b <0.16 c <0.04 Seeds (granivores) 1222 <0.05 <0.04 <0.01

aexceeds acute high risk (RQ $ 0.5), restricted use (RQ $ 0.2) and endangered species level of concern (RQ $ 0.1)
b exceeds acute restricted use (RQ $ 0.2) and endangered species level of concern (RQ $ 0.1)
C exceeds acute endangered species level of concern (RQ $ 0.1)

Table 19. Chronic RQ values for mammals feeding on short grass, tall grass, broadleaf plants/insects, and seeds exposed to PCNB following single and multiple applications based on a NOEL of 200 ppm.

Use/App. Method Application Rate lbs. a.i./A (# app / interval, days) Food Items Maximum EEC (mg/kg) a Chronic Mammalian RQ
Body weight (g)

15 35 1000

Cabbage 22.5
(1 / NA) Short grass 5400 513 a 356 a 81 a
Tall grass 2475 235 a 163 a 37 a
Broadleaf plants/small insects 3038 289 a 200 a 46 a
Fruits, pods, and large insects 338 32 a 22 a 5 a
Seeds (granivores) 338 7 a 5 a 1 a

Peanuts SLN (TX)

10
(1 / NA) Short grass 2400 228 a 158 a 36 a Tall grass 1100 105 a 73 a 17 a Broadleaf plants/small insects 1350 128 a 89 a 20 a Fruits, pods, and large insects 150 14 a 10 a 2 a Seeds (granivores) 150 3 a 2 a 0.45 SLN (TX)

5
(2 / 30) Short grass 1862 177 a 123 a 28 a Tall grass 854 81 a 56 a 13 a Broadleaf plants/small insects 1048 100 a 69 a 16 a Fruits, pods, and large insects 116 11 a 8 a 2 a Seeds (granivores) 116 2 a 2 a 0.35Use/App. Method Application Rate lbs. a.i./A (# app / interval, days) Food Items Maximum EEC (mg/kg) a Chronic Mammalian RQ
Body weight (g)

15 35 1000

51 3.2475
(3 / 7) Short grass 2049 195 a 135 a 31 a Tall grass 939 89 a 62 a 14 a Broadleaf plants/small insects 1152 109 a 76 17 a Fruits, pods, and large insects 128 12 a 8 a 2 a Seeds (granivores) 128 3 a 2 a 0.38

Potato SLN (ID,OR,WA)

5
(4 / 7) Short grass 3946 375 a 260 a 59 a Tall grass 1808 172 a 119 a 27 a Broadleaf plants/small insects 2220 211 a 146 a 33 a Fruits, pods, and large insects 247 23 a 16 a 4 a Seeds (granivores) 247 5 a 4 a 0.74

Turf SLN (CA, OR, WA)

43.56
(2 / 7) Short grass 19555 1858 a 1291 a 293 a Tall grass 8963 851 a 592 a 134 a Broadleaf plants/small insects 11000 1045 a 726 a 165 a Fruits, pods, and large insects 1222 116 a 81 a 18 a Seeds (granivores) 1222 26 a 18 a 4 a

aexceeds chronic risk level of concern (RQ $ 1.0)
Nontarget Aquatic Animals
Surface water concentrations resulting from PCNB a pplication to selected crops were predicted with the Tier II models PRZM-EXAMS. Five scenarios were simulated: cabbage (cole crops), cotton, peanuts, potatoes and turf. Peak EECs were then compared to acute toxicity endpoints to derive acute risk quotients. The 21-day EECs were compared to chronic toxicity e ndpoints (NOEC) to derive chronic risk quotients for freshwater ( Table 20 ) and estuarine/marine organisms ( Table 21 ). Although benthic sediment exposure estimates are provided by PRZM/EXAMS, this risk assessment does not estimate risk through this route of exposure. Also, although there is a higher ( 

### a greater) maximum rate for turf than the one used to determine EEC’s, it is an allowed usage only in California,, Washington, and Oregon. Based on the higher turf application rate of 43.56 lb a.i./A applied twice at a 7-day interval, the acute EEC was 16.0% greater (299.9 ppb vs . 258.6 ppb) and the chronic EEC’s we re 12.3% (invertebrates; 209.5 ppb vs . 186.6 ppb) and 26.0% (fish; 174.7 ppb vs . 138.6 ppb) greater.
For the current application rates modeled on the ma jor crops where PCNB is applied, acute risk, restricted use and endangered species LOC’s are exceeded (RQ $ 0.5) for freshwater fish following at current maximum application rates for cole crops, peanuts and turf (RQ range 0.84 - 2.6); acute restricted use and endangered species LOC’s (RQ $ 0.1) are exceeded for cotton (RQ=0.28) and potatoes (RQ=0.22). Chronic risk LOC’s (RQ $ 1.0) are exceeded for freshwater fish (RQ range 1.5 - 8.3) on all crops modeled except potatoes (RQ = 0.8). For freshwater invertebrates the acute restricted use and endangered species LOC’s52 are exceeded for cole crops, peanuts and turf (RQ range : 0.11 - 0.34); the chronic risk LOC is exceeded for all crops (RQ range: 1.1 - 6) except potatoes (RQ=0.6).
While no acute LOC’s for estuarine/marine fish were exceeded ( Table 21 ) for any of the major crops modeled, the likelihood of adverse chronic effects is uncertain since no data were available to assess the chronic toxicity of PCNB to estuarine/marine fish. Es tuarine/marine invertebrates appeared to be much more sensitive to PCNB than their freshwater counterparts on an acute exposure basis; acute risk, restricted use and endangered species LOC’s for estuarine/marine inverteb rates are exceeded for all major crops modeled (RQ range: 1.8 – 22).
Table 20. Acute and chronic risk quotients for freshwater animals exposed to PCNB based on a bluegill sunfish acute LC 50 of 100 μg/L and chronic NOEC of 13 μg/L and an acute Daphnia magna EC 50 of 770 μg/L and chronic NOEC of 18 μg/L.

Crop Application Rate (# of apps) EECs Acute Risk Quotients Chronic Risk Quotients

Peak / 21-day Average ( : g/L) Freshwater Fish a LC 50 = 100 : g/L Freshwater Invertebrate b LC 50 = 770 : g/L Freshwater Fish a NOEC = 13 : g/L Freshwater Invertebrate b NOEC = 18 : g/L
Cole crops 30 (1) 84.1 56.1 0.84 c

– 0.11 d.

– -- 4.3 f – 3.1 f

Cotton 2.0 (1) 27.8 20.0 0.28 d

– 0.04

– – 1.5 f – 1.1 f

Peanuts 10 (1) 97.4 45.9 0.97 c

– 0.13 d

– – 3.5 f – 2.6 f

Potatoes 25 (1) 22.0 10.9 0.22 d

– 0.03

– – 0.8 – 0.6

Turf 32.67 (2) 258.6 106.1 2.6 c

– 0.34 d

– -- 8.2 f -- 5.9 f

aRainbow trout ( Oncorhynchus mykiss )
b Water flea ( Daphnia magna )

c exceeds acute high risk (RQ $ 0.5), restricted use (RQ $ 0.1) and endangered species level of concern (RQ $ 0.05)
d exceeds acute restricted use (RQ $ 0.1) and endangered species level of concern (RQ $ 0.05)

e exceeds acute endangered species level of concern (RQ $ 0.05)
f exceeds chronic level of concern (RQ $ 1.0)53 Table 21. Acute risk quotients for estuarine/marin e animals exposed to PCNB based on a sheepshead minnow acute LC 50 of 7900 μg/L and a mysid shrimp LC 50 of 12 μg/L .

Crop Application Rate (# of apps) EECs Acute Risk Quotients

Peak ( : g/L) Estuarine/marine Fish a LC 50 = 7900 : g/L Estuarine/marine Invertebrate b LC 50 = 12 : g/L
Cole crops 30 (1) 84.1 0.01 7.0 c

Cotton 2.0 (1) 27.8 <0.01 2.3 c

Peanuts 10 (1) 97.4 0.01 8.1 c

Potatoes 25 (1) 22.0 <0.01 1.8 c

Turf 32.67 (2) 258.6 0.03 22 c

aSheepshead minnow ( Cyprinodon variegatus )
b Mysid shrimp ( Mysidopsis bahia )

c exceeds acute high risk (RQ $ 0.5), restricted use (RQ $ 0.1) and endangered species level of concern (RQ $ 0.05)
d exceeds acute restricted use (RQ $ 0.1) and endangered species level of concern (RQ $ 0.05)

e exceeds acute endangered species level of concern (RQ $ 0.05)
f exceeds chronic level of concern (RQ $ 1.0)

Seed Treatment Applications and Non-target Exposure

Birds
The avian acute RQ values listed in Table 22 were calculated according to the two methods described previously in this chapter. All acute RQ values for both methods and for all crops examined are less than the reported value since no upper limit was observed in the toxicity study. While there endangered species LOC exceedances in seven of the crops modeled, PCNB is considered practically non-toxic to birds on an acute exposure basis and, therefore, OPP believes these exceed ances to be an artifact and not an actual indication of acute risk. The chronic avian risk was estimated using the peak concentration on the seed, as well as the NOAEC from the avian reproduction study (mallard duck NOAEC = 600 mg/kg, no LOAEC was reported for birds). Chronic RQ values ranged from 0.46 – 3.8. Four of the crops examined ( i.e ., beans, corn, sorghum and wheat) are below the chronic risk LOC; all other crops modeled exceed this LOC.54 Table 22. Summary of avian acute and chronic ri sk quotients for PCNB based on three methods of estimating exposure based on a mallard duck acute oral LD 50 of >5,620 mg kg -1 body weight and a chronic NOAEC of 600 mg kg -1 of diet. Crop EEC mg a.i./day Acute RQ Method 1 a EEC mg ai./ft 2 Acute RQ Method 2 b EEC mg/kg

seed Chronic RQ c

Barley 296 <0.19 d 1.22 <0.04 1171 2.0 e

Bean 119 <0.07 0.78 <0.02 469 0.78

Corn 119 <0.07 0.12 <0.01 469 0.78

Cotton 573 <0.36 d 0.43 <0.01 2265 3.8 e

Oats 435 <0.27 d 2.29 <0.07 1718 2.9 e

Peas 237 <0.15 d 1.76 <0.06 937 1.6 e

Peanuts 138 <0.09 0.77 <0.02 547 0.91

Rice 352 <0.22 d 2.32 <0.07 1390 2.3 e Sorghum 69 <0.04 0.02 <0.01 273 0.46 Soybeans 237 <0.15 d 0.98 <0.03 937 1.6 e Sugar Beets 425 <0.27 d 0.14 <0.01 1679 2.8 e

Wheat 119 <0.07 0.66 <0.02 469 0.78

aAcute RQ Method 1 = mg kg -1 day -1 / LD 50 b Acute RQ Method 2 = mg ft 2 / LD 50
c Chronic RQ = mg kg -1 seed / NOAEC
d Exceeds acute endangered risk (RQ > 0.1) level of concern

e Exceeds chronic risk (RQ $ 1.0) level of concern55 Mammals
The mammalian acute RQ values ( Table 23 ), similar to birds, were calculated using the methods described previously in this chapter. None of the uses modeled produced an acute risk LOC exceedance. The LD 50 reported for rats was greater than 5,050 mg kg -1 , so all estimated RQ values are potentially less than the calculated value; therefore, OPP believes that the risk of acute mortality is negligible. The chronic risk LOC’s are exceeded (RQ range: 1.4 – 11) for all of the uses modeled.

Table 23. Summary of mammalian acute and chronic risk quotients for PCNB using three methods of estimating exposure based on a rat acute oral LD 50 >5050 mg kg -1 and a chronic NOAEC of 200 mg kg -1 of diet.

Crop EEC mg a.i./day Acute RQ Method 1 a EEC mg ai./ft 2 Acute RQ Method 2 b EEC mg/kg

seed Chronic RQ c Method 3 Barley 172 <0.02 1.22 <0.01 1171 5.9 d

Bean 69 <0.01 0.78 <0.01 469 2.3 d

Corn 69 <0.01 0.12 <0.01 469 2.3 d

Cotton 332 <0.04 0.43 <0.01 2265 11 d

Oats 252 <0.03 2.29 <0.02 1718 8.6 d

Peas 137 <0.02 1.76 <0.01 937 4.7 d

Peanuts 80 <0.01 0.77 <0.01 547 2.7 d

Rice 204 <0.02 2.32 <0.01 1390 7.0 d
Sorghum 40 <0.01 0.02 <0.01 273 1.4 d
Soybeans 137 <0.02 0.98 <0.01 937 4.7 d
Sugar Beets 246 <0.03 0.14 <0.01 1679 8.4 d

Wheat 69 <0.01 0.66 <0.01 469 2.3 d

aAcute RQ Method 1 = mg kg -1 day -1 / LD 50 b Acute RQ Method 2 = mg ft 2 / LD 50
c Chronic RQ = mg kg -1 seed / NOAEC
d Exceeds chronic risk (RQ $ 1.0) level of concern56 Risk Discussion
Based on a national, deterministic screening-leve l assessment of fate (environmental exposure) and toxicity data (ecological effects) for PCNB, chronic risk to terrestrial animals (birds and mammals) and both acute and chronic risk to aquatic animals (fish and i nvertebrates) is possible from the current major labeled uses of PCNB modeled in this evaluation. Although PCNB is not mobile in most soils, the chemical and its degradates are sufficiently persistent to possibly result in environmental concentrations similar to those that have, in laboratory studies, resulted in adverse eff ects to nontarget animals. PCNB and its degradates bioconcentrate; thus, environmental concentrations can be amplified to levels where effects are more likely. Additionally, the effects of PCNB may not be limited to organisms in close proximity to PCNB use since the chemical is also subject to long-range atmospheric transport.
Major uncertainties associated with this assessment include the degree to which volatilization will impact exposure, the potential effects of PCNB on plants (terrestrial and aquatic), the endocrine disrupting potential of the compound, and potential effects of PCNB degradates along with the contaminant HCB. OPP believes the predominate risk from PCNB is associatedwith aquatic animals based on the likely presence of the PCNB and its degradates in sediments and the water column coupled with the ability of aquatic plants and animals to bioconcentrate these compounds. Additionally, ch ronic risk to birds is a concern. OPP is uncertain regarding the relevancy of the chronic mammalian measurement endpoints to chronic risk assessment endpoints. The persistent, toxic, and bioaccumulative properties of PCNB and its degradates in the aquatic environment are major concerns surrounding th e current labeled uses of this fungicide.
PCNB has been characterized as having over 1,700 product-use pattern combinations; exposure and effects evaluated in OPP’s assessment are based on a lim ited number of major agricultural uses and surrogate species toxicity data. The environmental e xposure assessment is based on those uses considered representative of maximum application rates in term s of pounds active ingredient applied per season and/or representative of major crops (turf, potatoes, cabbage , peanuts and cotton) on which PCNB is used. These uses were selected as they represent 86% of total u se nationally. This ecological risk assessment does not take into account atmospheric transport in estimati ng environmental concentrations nor does it account for ingestion by animals of PCNB residues in drinking water or contaminated grit, ingestion through preening activities, or uptake through dermal absorption by terrestrial animals.

Estimated environmental concentrations determ ined for aquatic ecological exposure assessment do attempt to account for total residues of PCNB, i.e. , pentachloroaniline (PCA), pe ntachlorothioanisole (PCTA), pentachlorobenzene (PCB), pentachlorophenol (PCP), pentachlorothioanisole sulfoxide (PCTASO), pentachlorothioanisole sulfone (PCTASO 2 ) and/or hexachlorobenzene (HCB), inclusive of volatiles; whereas, terrestrial exposure assessment accounts for the parent compound alone. While several degradates/biotransformation products (PCB and PCP) or impurities (HCB, PCB) have sources other than PCNB, OPP has not accounted for these alternate sources in its assessment. It is likely, though, that the contribution to the environmental loads of PCP and PCB from the use of PCNB are insignificant compared with the industrial uses of these compounds. HCB is in the PCNB formulation as a manufacturing impurity; the extent of contamination was not possible to assess.
Although OPP is not able to quantify the extent to which PCNB will undergo long-range atmospheric transport, this mechanism of transport will constitute a route of exposure for nontarget animals distant from use sites. Based on its vapor pressure, PCNB will ex ist almost exclusively in the vapor phase in the atmosphere. The estimated photo-oxidation half-life fo r PCNB in the vapor phase is estimated to be 2,20057 days, so degradation in the atmosphere is expected to be negligible given that the compound is also hydrolytically stable.
OPP does not believe that PCNB use will represent a risk of acute mortality to birds based on the available data. PCNB is practically nontoxic to birds on both an acute oral (LD 50 >2,250 mg/kg bw) and subacute dietary (LC 50 >54,000 mg/kg diet/day) exposure basis. Therefore, whether birds are consuming treated seeds or foliar residues, there is no evidence to suggest that acute mortality in birds will be likely from current labeled uses of PCNB.
Similarly, PCNB is practically nontoxic to mammals on an acute exposure basis, as no mortality was observed at the highest dose (LD 50 >5,050 mg/kg bw) tested. Therefore, the estimated risk of acute mortality in mammals due to current labeled uses of PCNB is low (RQs<3.7).
Although OPP does not typically evaluate risks to insects, PCNB is practically nontoxic to bees (LD 50 >0.1 μg/bee)
Owing to high maximum application rates (3.2 - 44 lbs a.i./A for all crops modeled for terrestrial animals, PCNB residues on terrestrial feed items are suffi ciently high to exceed chronic risk levels of concern (RQ $ 1.0) by factors ranging from 1 to 33, for birds feeding on short and tall grasses and broadleaf plants/insects. On turf, chronic risk LOC’s are ex ceeded across all avian food categories including fruits, pods, seeds and large insects. Although cotton is a major use of PCNB, it was not modeled for terrestrial exposure estimates since, according to the registrant, there are no foliar uses of PCNB on cotton. Uses with high application rates such as turf (2 applications of 44 lbs a.i./A) have correspondingly high exceedances ( e.g . RQ=33 for birds feeding on short grass). Chronic toxicity is also possible from the consumption of PCNB-treated seeds; chronic risk LO C’s are exceeded for 58% of the crops modeled by factors ranging from 1.6 to 3.8. Chronic effects to birds included a reduction of 14-day survivors (NOEC = 600 ppm); however, at much higher concentrations, i.e. , 11,200 and 22,000 ppm, significant reducti ons in the number of eggs laid, number of hatchlings, and number of viable embryos ar e reported. Based on current labeled use rates and estimated environmental concentrations though, it is possible that PCNB residues will reach the concentrations where these additional chronic endpoints have been reported.
Chronic risk LOC’s for mammals (based on an NOAEC of 200 ppm) are exceeded across all food categories and labeled uses evaluated by factors ranging from 1 to 1858 except for larger-sized (1000 g) mammals feeding on seeds following application to cabba ge, peanuts and potatoes. Chronic risk LOC’s are also exceeded following consumption of PCNB-treated seed for all of the uses modeled by factors ranging from 1.4 to 11. Chronic exposure to mammals can aff ect both the liver and thyroid leading to hypertrophy in both organs and follicular cell hyperplasia in th e thyroid; however, the relevance of these measurement endpoints to ecological assessment endpoints of impaired reproduction, growth and survival is not clear. The two-generation rat reproduction study on which the mammalian risk assessment is based concluded that there were no treatment-related effects on survival, growth or reproduction in either the first or second-generation parental group nor were there treatment-related effects on reproduction, survival or growth in the first and second-generation offspring.
Terrestrial exposure assessment relied on a default foliar dissipation half-life of 35 days since no data were available specific to PCNB; however, even with a considerably shorter foliar dissipation value, it is likely that chronic terrestrial LOC’s would be exceeded . It is likely that the volatility of PCNB will reduce exposure, especially from foliar surfaces. Also, so il incorporation of PCNB-treated seeds will reduce the likelihood of exposure; however, it is not possible to quantify the extent to which exposure would be reduced.58 In spite of PCNB’s limited solubility in water, moderate volatility and its limited mobility in most soils, estimated water column concentrations (in a st andard water body) across the five scenarios evaluated were sufficiently high to exceed acute risk LOC’s (RQ range: 0.22 - 2.6) for freshwater fish; chronic risk LOC’s for freshwater fish (RQ range: 1.5 - 8.3) are ex ceeded for all crops except potatoes. For freshwater invertebrates, acute endangered species (RQ range 0.11 - 0.34) are exceeded on three crops (cabbage, peanuts and turf) and chronic risk LOC’s (RQ range: 1.1 - 6) are exceeded on four crops (cabbage, cotton, peanuts and turf); however, for potatoes no acute or chronic ri sk levels of concern ar e exceeded are exceeded for freshwater invertebrates. The high RQ values for tu rf reflect the relatively high maximum application rate (2 applications of 32.6 lbs a.i./acre) used.
For estuarine/marine fish, the LC 50 value (7.9 mg/L) exceeds the sol ubility of PCNB in water (0.44 ppm at 25 o C) and no acute risk LOC’s are exceeded; however , estuarine/marine invertebrates were the most sensitive nontarget animals tested (mysid shrimp LC 50 = 0.012 ppm) and acute risk LOCs are exceeded (RQ range: 1.8 - 22) across all of the labeled uses modeled. Since no chronic toxicity data were available for estuarine/marine animals, no risk quotients were calcu lated; however, if the acute-to-chronic ratio (ACR = acute EC 50 /chronic NOEC) for freshwater invertebrates (rainbow trout ratio: 0.1/0.013=7.7; Daphnia magna ratio: 0.77/0.018 = 42.8) a NOEC of 1.02 ppm and 0.3 ppm can be estimated to represent the sensitivity of estuarine/marine fish and invertebrates, respectivel y, to total residues of PCNB. Using the estimated NOEC’s, no chronic risk LOC is exceeded for estuarine /marine fish; however, chronic risk LOC’s would be exceeded for estuarine/marine invert ebrates across all modeled uses by factors ranging from 35X to 925X.
No data were available to assess the toxicity of PCNB to terrestrial or aquatic plants; however, ASTER model toxicity estimates suggest that increasing the number of chlorine substitutions on the benzene ring from chlorobenzene to pentach lorobenzene increases the toxicity of the compound by an order of magnitude.
Although not frequently detected in NAWQA monitori ng data, PCNB has been detected in a low percentage (0.2%) of field samples across the U. S.; however, none of these data were from targeted monitoring studies. Monitoring data also show that PCNB and its degradates have been associated with benthic sediments. Open literature data confirm th at PCNB bioconcentrates and that sediment-dwelling invertebrates and bottom-feeding fish contain measura ble quantities of PCNB degradates. Aquatic plants have demonstrated bioconcentration factors ranging from 4,500X to as high as 22,000X (Korte et al. 1978; Wang 1996) and may reflect the inability of algae to metabolize PCNB. Fish exhibited bioconcentration factors around 1,000X.
While chronic effects are anticipated for terrestrial species, the presence of PCNB and its affinity for soil/sediment organic matter make benthic aquatic co mmunities particularly vulnerable to PCNB exposure and uptake. Unfortunately, OPP has no data to evaluate either the acute or chronic toxicity of PCNB or its degradates on benthic-dwelling organisms such as midge larvae ( Chironomis spp .). However, with estimated benthic sediment pore-water concentrations as high as 108 ppb and freshwater invertebrate sensitivities of 18 ppb, risk quotients (RQ = 108/18 or 6) based on estimated benthic exposure concentrations ( APPENDIX D4 ) exceed chronic risk levels of concern. Similarly, estuarine/marine invertebrates with the most sensitive EC 50 -value of 12 ppb (mysid shrimp) would also likely be at risk with RQ values as high as 9 (RQ=108/12).
Aquatic toxicity assays typically evaluate the biol ogical effects of chemicals present in the water phase. However, aquatic organisms might also be e xposed to organic chemicals that are deposited onto or assimilated into their food substrates. Thus, dietary upt ake is an additional route of exposure that should be considered in the toxicity assessment of chem icals such as PCNB that have a tendency to59 bioaccumulate/biomagnify. Although it is conceivable that toxic amounts of PCNB could be ingested by an aquatic omnivore, no food chain studies were identified in the open literature for this chemical to establish a relationship between concentrations in lower trophic level organisms and toxicity at higher tropic levels. However, in a food web study of the PCNB degradat e and contaminate pentachlorobenzene (PCB) in the Detroit River, PCB was highest for benthic invertebra tes with concentrations ranging from 5 to greater than 100 μ g/kg lipid (Russell et al. , 1999). Concentrations of PCB ranged from 8 to 20 μg/kg lipid in planktivorous/insectivorous feeding fish, from 2 to 9 μg /kg lipid in benthic feeding fish, and from 5 to 20 μg/kg lipid in piscivorus fish (Russell et al. , 1999).
The ability of lipophilic compounds such as PCNB and its degradates to partition across cell membranes and into lipid (fat) reserves plays an importa nt role in determining whether chemical body burden in aquatic organisms is determined by aqueous or dietary uptake or both (Qiao et al. , 2000). The low water solubility and large octanol-water partition coeffici ent values suggest that PCNB and its metabolites will bioconcentrate in aquatic organisms. Dietary ab sorption and metabolic half-lives are also important determinants of chemical body burden. However, the relatively low dietary absorption efficiency and short metabolic half-lives suggest that chloronitr obenzenes such as PCNB, chlorophenols such as pentachlorophenol (PCP), and chloroanilines such as pentachloroanaline (PCA) bioaccumulate to a lesser extent than chlorobenzenes such as pentachlorobenzene (PCB) and hexachlorobenzene (HCB) (Niimi et al. , 1989).
A single incident has been reported for PCNB in the Ecological Incident Information System and pertains to cotton plant damage (cotton seeds failed to germinate) following an unincorporated granular application of PCNB; however, no data were available to evaluate the effects of PCNB on either terrestrial or aquatic plants. There are a total of sixteen incide nts involving freshwater fish kills that are associated with PCP with as many as 271,000 fish dead; however, the in cident reports are not de tailed enough to determine the source of the PCP. It is likely that PCP at a su fficient concentration to result in acute mortality would have originated from the use of this chemical as a wood preservative. These incidents underscore the uncertainty surrounding which conditions favor the forma tion of PCP as a degradate of PCNB and the relative contribution from other sources of this compound. Howe ver, as is the case for PCB, it is likely that the contribution to the environmental loads of PCP from th e use of PCNB is insignificant compared with that from the industrial uses of PCP.
Refined Conceptual Model
Since PCNB is practically nontoxic to terrestrial animals on an acute exposure basis, the likelihood of acute risk from PCNB and its degradates is low. Ho wever, because of the chemical’s persistence, chronic risk of reduced reproductive success and growth may o ccur as chronic risk levels of concern are exceeded for birds. Even though chronic risk LOC’s are exceed ed for mammals, there is uncertainty regarding the relevancy of the measurement endpoints (hepatic/thyroi dal hyperplasia) to chronic risk assessment endpoints of impaired reproduction, growth a nd/or survival. Although in the aquatic environment PCNB will most likely be associated with benthic sediments, estimated water column concentrations from Tier II modeling indicate that acute mortality and chronic reproductive/gr owth effects may result in both freshwater fish and invertebrates from current uses of PCNB. Thus, the primary conceptual model for depicting the risks of PCNB to nontarget animals is one that focuses on birds and aquatic animals (vertebrates and invertebrates) where exposure results from a combination of spray-drift and runoff ( Figure 3 ) and potential trophic transfer through the food chain..60 PCNB Application to Foliage / Soil

PCNB Biolysis

Chemolysis

Spray Drift Runoff / Erosion

Aquatic Environments Leaching / Subsurface Transport PCP PCA PCTA PCB PCTASO PCTASO 2

Dermal Uptake Gill Uptake Ingestion

Biomagnification Bioconcentration

Vertebrates / Invertebrates

Sublethal Effects Acute Mortality Chronic Effects Terrestrial Environments

Dermal Uptake Ingestion

Birds

Chronic Effects PCNB Application to Foliage / Soil

PCNB Biolysis

Chemolysis

Spray Drift Runoff / Erosion

Aquatic Environments Leaching / Subsurface Transport PCP PCA PCTA PCB PCTASO PCTASO 2

Dermal Uptake Gill Uptake Ingestion

Biomagnification Bioconcentration

Vertebrates / Invertebrates

Sublethal Effects Acute Mortality Chronic Effects Terrestrial Environments

Dermal Uptake Ingestion

Birds

Chronic Effects PCNB Application to Foliage / Soil

PCNB Biolysis

Chemolysis

Spray Drift Runoff / Erosion

Aquatic Environments Leaching / Subsurface Transport PCP PCA PCTA PCB PCTASO PCTASO 2

Dermal Uptake Gill Uptake Ingestion

Biomagnification Bioconcentration

Vertebrates / Invertebrates

Sublethal Effects Acute Mortality Chronic Effects Terrestrial Environments

Dermal Uptake Ingestion

Birds

Chronic Effects Figure 3. Refined conceptual model depicting ecological risk based on current uses of PCNB.

Endocrine Disruption Potential
Based on information reported in open literature, PC NB, its major degradate PCTA, and its potential degradate PCP have the ability to bind estrogen recep tors and are therefore potential endocrine-disrupting compounds (Motoyama et al. , 2001; Zou et al. 2002). Both PCTA and PCP showed competitive binding on the estrogen receptor " , similar to the level exhibited by organoc hlorine insecticide dieldrin. Additionally, OPP is uncertain whether the reproductive effects in bi rds and fish (decreased numbers of eggs) and thyroidal effects in mammals are indicative of the ability of PCNB to act on endocrine mediated processes.
EPA is required under the FFDCA, as amended by FQPA, to develop a screening program to determine whether certain substances (including all pesticide active and other ingredients) “ may have an effect in humans that is similar to an e ffect produced by a naturally occurring estrogen, or other such endocrine effects as the Administrator may designate .” Following the recommendations of its Endocrine Disruptor Screening and Testing Advisory Committee (EDSTAC), EPA determined that there was scientific basis for including, as part of the program, the androgen and thyroid hormone systems, in addition to the estrogen hormone system. EPA also adopted EDSTAC’s reco mmendation that the Program include evaluations of potential effects in wildlife. For p esticide chemicals, EPA will use FIFRA and, to the extent that effects in wildlife may help determine whether a substance may ha ve an effect in humans, FFDCA authority to require the wildlife evaluations. As the science develops and resources allow, screening of additional hormone systems may be added to the Endocrine Disruptor Screening Program (EDSP). When the appropriate61 screening and/or testing protocols being considered under the Agency’s EDSP have been developed, PCNB may be subjected to additional screening and/or testi ng to better characterize effects related to endocrine disruption.

Uncertainties
In attempting to understand the potential ecological risks associated with the labeled uses of PCNB, OPP has identified a number of uncertainties lacking su fficient data to resolve certain aspects of the likely exposure and or effects resulting from the use of PC NB. Very limited information exists on whether pentachlorophenol (PCP) is a likely degradate of PCNB and which, if any, circumstances favor the formation of PCP. Additionally, given that PCP is used as a wood preservative, there is uncertainty regarding the cumulative exposure to PCP from various sources.
The degree to which volatilization from soil/plants will decrease exposure to aquatic organisms and exposure levels in surface water used for drinking is not known. The currently used version of the PRZM/EXAMS model used to gene rate EDWC’s and EEC’s is una ble to account for volatilization. However, volatilization should be a significant route of dissipation of the parent and the degradate PCA when PCNB is not incorporated into the soil. This will o ccur when the pesticide is applied as a foliar spray ( e.g. , to turf) or is applied by chemigati on (through overhead sprinkler irrigation; e.g. , to potatoes. Based on modeling results from a provisional version of PRZM/EXAMS (PRZM9; dated November 10, 2004), for which a QA/QC has not yet been completed by EFED, the estimated acute surface water concentrations from turf use are predicted to decrease by approximately 25-27% (for drinking water and ecological exposure) when volatilization is accounted for. However, because the solubility limit of 440 ppb is used for the EDWC (in lieu of the previous model output value of 586.4 ppb) , the effective decrease from taking volatilization into account is only 1.9% for acute exposure. Chronic drinking water exposures for turf use are predicted to decrease by approximately 34%, while chronic ecological exposures for turf use (21- and 60-day values) are predicted to decrease by approximately 22% and 28%, respectively, when volatilization is accounted for.
Although monitoring data indicate that PCNB undergo es long-range atmospheric transport, data are not available to assess the impact of that route of exposure to nontarget animals distant from use sites.
Data on the foliar dissipation half-life of PCNB ar e not available and therefore terrestrial exposure assessments relied on the default value of 35 days. Wh ile volatility may substantially reduce the amount of PCNB residues following foliar applications, there were no data submitted to dete rmine a more appropriate value for use in terrestrial exposure assessments.
Open literature indicates that PCNB and its major degradate, pentachlorothioanisole, and it potential degradate, pentachlorophenol, bind to estrogen recepto rs. Additionally, several of the chronic effects (reduced number of eggs produced, thyroid hyperplasi a) noted across taxonomic groups are consistent with endpoints that OPP uses to identify chemicals with a pot ential to impact endocrine-mediated processes. Since current chronic toxicity testing protocols are not necessarily sensitive measures of a chemical’s endocrine disrupting potential, we are not able to determine whether PCNB should be characterized as an endocrine disruptor. Toxicity endpoints measured in chronic studies meet the criteria though for further testing of PCNB as an endocrine disruptor.
Data on the toxicity of PCNB to sediment-dwelli ng invertebrates are not available. The likely presence of PCNB in benthic sediments could serve as a route of entry into aquatic food chains.62 Chronic data for PCNB on estuarine/marine fish or invertebrates are not available. Given the use of PCNB on golf courses, the proximity of some golf courses to coastal areas, and the use of PCNB on crops, e.g. cole crops, grown in coastal locations coupled withthe likely persistence of the compound, there is a potential for chronic exposure in estuarine environments.
Data on the toxicity of PCNB to terrestrial, semi-a quatic, or aquatic plants are not available; however, the only incident reported in the Ecological Incident Information System for PCNB involves plants and suggests that plants may be sensitive to PCNB. Additionally, the propensity for aquatic plants to bioconcentrate PCNB by factors as high as 22,000X underscores the need for better understanding the effects of PCNB on plants.
Endangered Species
Avian and mammalian chronic risk and aquatic acute and chronic risk LOC’s are exceeded based on OPP’s modeling of current PCNB uses in our screening-level risk assessment. The Office of Pesticide Programs recently published on its web site ( http://www.epa.gov/oppfead1/endanger/consultation/ecoriskoverview.pdf ) an overview of our ecological risk assessmen t process for threatened and endangered species. Because of the timing of that document and the fact that it still may undergo slight changes, the process described therein was not utilized for this screeni ng-level endangered species risk assessment. The Agency will reassess the potential risk of PCNB use to endangere d species using the new process at a later date and consult as appropriate with the Fish and Wildlife Servi ce and National Marine Fisheries Service at that time.

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Wang, C.H. and F. E. Broadbent. 1972. Kinetics of losses of PCNB and DCNA in three California soils. Soil Sci. Soc. Amer. Proc. 36:742-745.
Wang, X. , S. Harada, M. Watanabe, H. Koshikawa and H. J. Geyer

. 1996. Modeling the bioconcentration of hydrophobic organic chemicals in a quatic organisms. Chemosphere 32:1783-93.
Willis, Guye H., and Leslie.L. McDowell, 1987. Pesticide Persistence on Foliage. in Reviews of Environmental Contamination and Toxicology . 100:23-73.
Zou, E., M. Hatakeyama and F. Matsumura. 2002. Foci fo rmation of MCF7 cells as an in vitro screening method for estrogenic chemicals. Environmental Toxicology and Pharmacology 11 (2): 71 - 77.68 APPENDIX A1. USE CLOSURE MEMO

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES January 23, 2003

MEMORANDUM

FROM: Jill Bloom, Review Manager /s/ SRRD/Reregistration Branch 2 (7508C)

TO: PCNB RED Team

SUBJECT: Use Closure for PCNB Reregistration–Draft, Subject to Revision
We held a Smart Meeting with registrants and othe r interested parties on July 17, 2001. Utilizing use and usage information supplied by the registrants for th at meeting and subsequent research inside and outside EPA, I have drafted the Agency’s record of comm on understanding on the uses to be included in the human health and environmental risk assessments for PCNB. Th is record also covers responses to specific questions from the team.
I have asked the registrants to review this documen t with an eye to correcting out-of-date information and supplying missing information from their initial responses.
Furthermore, this document may be revised by comparison to the most recent LUIS report. I invite the team to provide comments on this memo. I have scheduled a team meeting for January 29, 2003 on this use closure memo and other RED development issues (p lease refer to the LotusNotes invitation for details) . If you wish to contact me via the telephone, my number is 703-308-8019.
Registrants
Uniroyal and Amvac are supporting re gistrations with soil and seed tr eatment applications. Gustafson is the primary seed treatment registrant.

Uses
PCNB is a fungicide used to control diseases on vegetables (cole crops, eggplants, peppers, green beans, peas), field crops (cotton, peanuts, potatoes, tob acco), mushrooms, turf, and ornamentals. It is applied both to soil and seeds.69 The following food/feed uses of PCNB will be s upported through reregistration (predominant uses in bold):
Amvac: beans (dry, snap [bush, pole], succulent), cole crops (broccoli, Chinese bro ccoli, Brussels sprouts, cabbage, Chinese cabbage, cauliflower, collards, kale, mustard greens), cotton , garlic, peanut , peppers, potatoes , tomatoes; seed treatments (barle y, beans, corn, cotton, oats, peas, safflower, sorghum, soybeans, sugar beets, rice, wheat). Also seed treatments (Amv ac sells technical to Gustafson): barley beans, corn, cotton, oats, peanuts, peas, rice, safflow er, sorghum, soybeans, sugar beets, wheat
Gustafson (seed treatments): barley, beans, corn, cotton , oats, peas, peanut , rice, safflower, sorghum, soybean , sugar beet, wheat
Uniroyal: beans (dry, succulent, snap ), cole crops ( broccoli , Chinese broccoli, Brussels sprouts, cabbage , Chinese cabbage, cauliflower , collards, kale, mustard greens), cotton , garlic, hot pepper, peanuts , peppers , potato seed piece (ME79000100), tomatoes
Complete list of soil treatment sites: beans, cole cr ops, cotton, garlic, hot peppe r, peanut, peppers, potatoes, tomatoes
Complete list of seed treatments sites: barley, beans, co rn, cotton, oats, peas, peanut, rice, safflower, sorghum, soybeans, sugar beets, rice, wheat
The following non-food uses of PCNB will be s upported through reregistration (predominant uses in bold):
Amvac: ornamental plants (bedding, cut flower s, flowering, foliage, tropical foliage, woody), ornamental lawns and turf (grasses and dichondra)
Uniroyal: turf ( golf courses , home lawns, institutional areas, sod farms), mushroom farms (outdoor areas), ornamentals (bedding, bulb soak, cut flowers, flowering, foliage, trees, woody)70Application MethodsTable 1. Application methods and formulation types for food use sites

Site At cultivation Band Band row Broadcast Chemigation Clove treatment In-furrow Row or row drench Seed treatment Transplant solutionbarleynot specifiedbean ECFGWPWSPECFGWSPWPEC not specifiedcole crop ECFGWSPWPECFGWSPWPECFGWSPWPECFWPWSPcornD*F*cotton EC ECFGWSPWPD*F**garlicECFG?WPWSPECFGWPWSPhome gardenveggiesG GSite At cultivation Band Band row Broadcast Chemigation Clove treatment In-furrow Row or row drench Seed treatment Transplant solution71hot pepperECFGWSPWPpeanot specifiedpeanut FGWPWSPECFGWPWSPECWPECFGWSPWPD***F*?pepperECFGWPWSPECFWPWSPoatsnot specifiedpotato F ECGECFECGricenot specifiedsafflowernot specifiedsorghumnot specifiedsoybeanD*F**sugar beetnot specifiedSite At cultivation Band Band row Broadcast Chemigation Clove treatment In-furrow Row or row drench Seed treatment Transplant solution72tomatoECFGWPWSPECFWPWSPwheatFLFor seed treatments:* on farm; ** commercial; *** both73Table 2. Application methods and formulation types for non-food use sites

Site Band Band row Broadcast Dip, direct spray Drench In-furrow Row or row drench Seed treatment Transplant solutionazaleas, camellias FGWPWSPG not specifiedbedding plants FGFWPFGWPWSPcalendula, larkspur, snapdragon,sweetpeaFGWPWSPcut flowersFgladiola FGWPFGWPWSPherbaceous,woody plantsGFFGWPWSPFbulbs FGWPWSPFGWPWSPFGWPWSPFGWPWSPSite Band Band row Broadcast Dip, direct spray Drench In-furrow Row or row drench Seed treatment Transplant solution74lily FGWPWSPFGWPWSPFpine FGWPWSProsesFGWPWSPtropical foliage plants FGFGWPWSPturf grass ECFGWPWSPdichondra FGWPWSP75 Additionally, Uniroyal states that its products may be applied to ornamentals by chemigation and through growth medium incorporation. Its flowable , granular, and wettable powder formulations may also be applied to mushroom farms via broadcast soil/su rface spray. Amvac says that granules may be aerially applied for peanuts (< 1% of applications to peanuts).
Application Timing
PCNB may be applied at any stage of crop growth. It is primarily applied just once per season, although multiple treatments may be made to turf. Timing can be categorized as:
1) seed treatment, at transplant
2) pre-plant
3) at planting
4) mid-season (1 to 6 weeks after initial treatment for beans, peanuts, potatoes, ornamentals; 4 months after initial top dressing for ornamentals; up to 19 treatments, 1 week apart, allowed annually on mushroom farm walkways and exterior surfaces)
5) at first appearance of disease on turf (approx. 3 weeks after initial treatment, 3 months after initial treatment for snow mold on turfgrass)76 Use Rates
Table 3. Use parameters for soil a nd transplant applications of PCNB
Application Rate lbs.ai/A # app lications application intervals
Use site minimum typical maximum maximum typical minimum typical
beans 1 1 2.06; not >10 lbs/yr ? 1 2 wks —

cole crops 11 11-18.75 15-30; 1.5-20 transplant sol’n 1 1 NA

cotton 0.75 0.75 3.75; 0.3 lbs/ 1000 lbs seed 1 1 NA

garlic --- — 10-20.6; 2.5 lbs /1000 lbs cloves 1 1 NA

hot peppers 1 1 1.5 1 1 NA
peanut 1 ? 10 2 1 30d(TX) NA

peppers, tomatoes 4.8 4.8 7.5; 3.75 transplant sol’n 1 1 NA

potatoes 2.5 ? 25; ? seed piece trt (SLN) ? 1 7d (ID, NV, OR, WA) ?77 Table 4. Treatment rates for seed, seed piece, and cloves treated commercially
Application Rate lbs ai/cwt
crop minimum typical maximum
barley 0.0394 0.1045 0.1307

bean 0.0256-0.0523

corn 0.0523

cotton 0.0656 0.2526 0.0788
garlic — — ---

oats 0.0394 0.0977-0.1045 0.1957
pea 0.0523 0.1045
peanut 0.0305 0.0375-0.0523 0.0610

potato — — ---

rice — — ---

safflower — — ---
sorghum — 0.0305 ---
soybean 0.0256 0.0256-0.0525 0.1045
sugar beet 0.0958 — 0.1873

wheat 0.0256 0.0256-0.0523 0.052578 Table 5. Treatment rates for seed, seed piece, and cloves treated on farm
Application Rate lbs ai/cwt, unless otherwise noted
crop minimum typical maximum
barley 0.0390 --- 0.0878

bean 0.0347 — 0.0750

corn 0.0372 --- 0.0558

cotton 0.0750 0.0750-0.1250 0.0150
garlic — — ---

oats 0.0302 — 0.0604
pea 0.0521 — 0.1042
peanut 0.0375 0.0375-0.0417 0.0750

potato — — ---

rice 0.0417 — 0.0926

safflower — — ---
sorghum — — ---
soybean 0.0695 — 0.1044
sugar beet 0.0313 — 0.0625

wheat 0.0347 — 0.0521
Table 6. Number of pounds per bushel for vario us crops (use to convert to lbs ai /cwt)

Number of pounds per bushel for various crops.

Crop Barley Bean Corn Cotton Peanut Pea Sorghum Soybean Oats Safflower Sugar beet Wheat Rice

Pounds 48 60 56 32 17 60 56 60 32 NA NA 60 45 Information obtained from Agricultural Statistics 2000.79 Responses to specific questions
Questions posed to registrant prior to SMART meeting:
1. What are the maximum label and typical (actual) application rates for each use? Does the application rate vary within individual crops, de pending on environmental or other factors? If so, what percent of crop is treated at the different application rates?
See Tables 3 and 4 above for application rates. Hi gher end use rates are more likely to be used in heavy and wet soils, cool climates, where there is minimum or reduced tillage, or when seed quality is poor. (The registrants have not responded to the last question in this series–could the registrants please address this point in their comments please?).
2. What are the maximum and typical number of applications per season?
For the most part, one application is made per season. Exceptions are detailed in Table 3. Some use sites limit total poundage per season.
3. What are the minimum and typical intervals between applications in one season?
Details are given in Table 3.
4. If you intend to support certain uses at lower thanthe maximum labeled application rate or number of applications, or with a greater than minimum application interval, please specify.
Neither Amvac or Uniroyal plans to reduce application rates or drop uses at this time.
5. Please describe all methods of application (air, ground, chemigation, injection, etc.). Please confirm that PCNB is applied aerially and through chemigation to peanuts.
Methods of application are shown inTables 1 and 2. Amvac: Chemigation is a labeled application method for peanuts and potatoes. Amvac states th at <1% of applications to peanuts are aerially applied. Uniroyal says there are no aerial applications of its PCNB products, and that its PCNB products are not applied to peanuts via chemigation. Uniroyal supplies this additional information:

For food and fiber seed plantings, Uniroyal’s PCNB products are applied using tractor-drawn in-furrow, banding, or broadcast equipment. Transplants are treatedat the time of planting, and garlic cloves are mistsprayed with product and sticker prior to planting. Equipment types were not detailed for transplants and garlic.80 Table 7. Equipment used in applying Uniroyal PCNB products to turf and ornamentals (more detailed information supplied in attachment to this memo from Uniroyal submission of 7/18/2001)
Equipment type Use site Formulation type
Tractor rear-mounted rotary-type applicator turf G
Push-type rotary applicat or turf spot treatments G
Tractor rear-mounted boom sprayer turf WP liquids
Hydraulic sprayer w/hand-held drench nozzle (water breakers) greenhouse-grown containerized ornamentals WP liquids
Overhead or drip tube irrigation greenhouse-grown containerized ornamentals WP liquids
Fully automated media incorporation greenhouse-grown containerized ornamentals G

Tractor-mounted 2-nozzle boom sprayer field-grown ornamentals; in-furrow and band applications multiple (see Table 2)

Tractor-mounted multi-nozzle boom sprayer f ield-grown ornamentals; broadcast applications (rare) multiple (see Table 2)

Automated tank soak bulb (dip) liquids

Amvac did not submit equivalent information.

6. For turf , what % of the pesticide is homeowner applied vs. professionally applied?
Amvac states that 95% of PCNB applications to tu rf are professionally applied. Uniroyal says that 95% of its turf products are applied to golf courses; 5% is applied to turf farms. Application at these sites is by professionals. Less than 0.5% of Un iroyal’s product use on turf is to home and garden. No estimate is given for professional use on these sites.
7. How much PCNB is applied/how many acres ar e treated per day and per season by a handler?
Amvac does not address. Uniroyal provides this information:81 Table 8. Amounts applied daily and seasonally by individual applicators
Use site Per day Per year
Cotton, in-furrow 500 A 2000 A
Peanuts, in-furrow 500 A 2000 A
Turf, worst-case 21 A 3700 lbs. ai (@ 43.5 lbs. ai/)
Ornamentals, greenhouse and field 1.5 A (1 or 2 people, w/hand-held equipment) see attached Uniroyal 7/18/2001 submission excerpt
8. For applications to trees where label rates are given as lbs of formulation per 100 gallons of water, please provide information on the number of trees treated per day by a handler and the number of gallons of diluted material per tree.
Neither Amvac nor Uniroyal supplied information.
9. For applications to cut flowers with a spray or di p, where rates are reported in lbs of formulation per 100 gallons of water, pl ease provide information on how many gallons of water are likely to be mixed and applied per day to cut flowers by a handler.
Neither Amvac nor Uniroyal supplied information.
10. For applications of surface spray treatments to outside surfaces of mushroom houses and weedy areas around them, where the rate is reported as lbs formulation per 1000 square feet treated, please supply information on the number of square feet likely to be treated by a handler in a day.
Uniroyal: The labeled use is for inside mushroom houses, but the product is not currently being used.
11. For seed treatment uses, please provide information on how many lbs of seed are treated by a handler in a day.
Gustafson provided information on the four crops most commonly treated with PCNB in commercial settings.82 Table 9. Typical quantities of seed trea ted with PCNB in commercial facilities

Crop Treating season lasts per hour per 7.5.hour workday
kg lbs kg lbs
Cotton 16 weeks 5,443 12,000 40,824 90,000
Peanut 16 weeks 4,082 9,000 30,618 67,500
Soybean 4-16 weeks 21,773 48,000 163,296 360,000
Wheat 12 weeks 6,804 15,000 51,030 112,500

12. For applications via watering-can, bulb soak, cut flower and dormant rose spray/dip, and transplant solution use patterns, please provide information on how much material a handler would apply in a day.
Amvac says these uses are not applicable to its products. Uniroyal provides this information:
Table 10. Transplant and ornamental uses; am ounts applied daily by individual applicators
Use site Daily usage
Field crops transplant solution plant 10 A/day
Turf and ornamentals; watering can no known use
Bulb soak 22.5 lbs. ai, maximum 12 times/year

Cut flower no known use
Dormant rose spray/dip not labeled for this use83 13. Describe personal protective equipment requirements and types. Describe equipment used for mixing and loading the pesticide (information on application methods is requested above).

Amvac:
Long-sleeved shirt, long pants, coveralls. Waterproof and chemical resistant gloves, shoes plus socks, protective eyewear, and Dust/mist filtering respir ators (TC-21C) for outdoor exposure, organic vapor removing cartridges with a prefilter approved for p esticides (TC-23C) or canisters ((TC14G) for indoor exposures. Chemical resistant apron required in a ddition to above when mixing and loading or cleaning equipment.
Uniroyal:
For field crops, varies by product. Long-sleeved shirt, long pants (or short-sleeved shirt, short pants and coveralls when combined with disulfoton or thimet ), waterproof or chemical resistant gloves, shoes + socks (or chemical resistant footwear + socks when combined with disulf oton or thimet), chemical resistant headgear and chemical resistant apron (when combined with disulfoton or thimet), protective eyewear, organic vapor/dust mist respirator.
For ornamentals and turf, varies by product. Often, no PPE is required; in some cases, only chemical resistant gloves and/or an organic vapor respirator is required.

Gustafson:
For commercially treated seed, mixers and loaders are required to wear long-sleeved shirt and long pants (or coveralls), shoes + socks, chemical resistant gloves, and chemic al resistant respirator (in some cases) or chemical resistant apron and goggles or face shield (in other cases). Applicators and other handlers are required to wear long-sleeved shirt and long pants (or coveralls), shoes + socks, chemical resistant gloves, and dust/mist filtering respirator or approved respirator w ith N, R, P, or HE filter (in some cases) or dust mask (in other cases)
For on-farm seed treatments, mixers, loaders, applicators, and other handlers are required to wear long-sleeved shirt and long pants (or coveralls), shoes + socks, chemical resistant gloves, dust/mist filtering respirator or approved respirator with N, R, P, or HE filter (in some cases) or dust mask (in other cases).84 14. Describe REIs for PCNB.
Amvac: 12 hours except when combined with Thiram (24 hours) or Disulfoton (48-72 hours). Uniroyal: 12 hours except when soil incorporated, or if combined with Disulfoton and/or Phorate, up to 48-72 hours, depending on average annua l rainfall in the area where applied.
15. How long are the PHIs for PCNB? What is the percent crop harvested at various PHIs?
Amvac: PHI is 45 days; most is a pplied at or near planting, so PHI doesn’t typically impact use practices. Peanuts may have an in-season application. Uniroyal: Since PCNB is applied once, at pre-plant, PHI is not an impediment to treatment.
16. Are there any rotational crop restrictions?
Amvac: Crop rotational restrictions are usually 12 months for sites not registered for PCNB use. Uniroyal: Cannot plan t root crops within 12 months of PCNB broadcast or banding applications unless registered for use on those crops.

17. Is a reduction in concentration factors associat ed with post-harvest processing (washing, trimming, blanching), transport, storage dnd cooking?
No, because PCNB is non-systemic.
18. Are there Federal or State imposed buffer ones for ground applications?

No.
19. Are there any groundwater restrictions? If so , describe specific uses and areas/sites to which restrictions apply.

No.
20. Are there any new chemical-speci fic monitoring data available for worker or dietary exposure, or ground-, surface, or drinking water?
Not to Amvac’s knowledge. Uniroyal: USDA’s P esticide Data Program Annual summary Calendar Year 1999 show a total of six detections in cucumber and fresh tomatoes only.
21. Will you be supporting any SLN registrations?
Amvac currently supports six SLN registrations; Uniroyal two.85 Table 11: Amvac SLN registrations
Registration Number Use sites
ID-000008 potatoes for white mold, via irrigation
NV-000005 potatoes for white mold, via irrigation
OR-000019 potatoes for white mold; via overhead irrigation
TX-920024 peanuts for white mold; via overhead irrigation
TX-900010 peanuts for white mold; via overhead irrigation
WA-000030 potatoes for white mold, via irrigation
Table 12: Uniroyal SLN Registrations
Registration Number Use sites
ME-790001 potato

PA-980001 mushroom
22. Is PCNB used in combination with any other pesticides?
Amvac: PCNB is commonly used in combination with another fungicide or insecticide, especially with applications to cotton, turf, potatoes, and seed treatments.
Uniroyal: PCNB is used in combination with etridiazole, disulfoton, and phorate for cotton; ethoprop for peanuts.
Gustafson: PCNB is combined with captan, carboxin, lindane, metalaxyl, TBZ, and B. subtilis in seed treatment formulations.
23. What alternatives are available? Are there any constraints such as cost, efficacy , or geographic concerns? What is unique about PCNB?
Amvac: There are alternatives, but PCNB is time-test ed, is used on a wide range of crops, is not prone to problems with resistance. For turf, very few produc ts offer comparable benefits in economics and overall performance. PCNB is especially used for controlling Rhizoctonia , and for seed treatments in protecting against Kernel bunt in wheat. For the latter disease, seed may be subject to country quarantine if the disease is untreated.86 Uniroyal: There are no alternatives with the same spectrum of control for cotton, peanuts, turf, ornamentals and vegetables. Resistance of fungal pathogens to PCNB has not been found, and none of the potential alternatives to PCNB has the same degree of residual disease control.
Gustafson: Newer chemistries can control a subset of diseases controlled by PCNB, some systemically, but do not have the broad spectrum of cont rol offered by PCNB. PCNB is applied at rates at least 10 times greater than these alternatives, and the cost of the higher rates is not constraining. PCNB can be viewed as a tool in preventing resistance developmen t especially when used in combination with the newer fungicides.
Potential alternatives as reported by the re gistrants are detailed in Tables 13 and 14.
Table 13. Alternative pesticide treatments fo r diseases controlled by PCNB (soil treatments)
Crop Disease PCNB Iprodione Azoxystrobin Tebuconazole

Cotton Rhizoctonia X X X

Fusarium X

Peanuts Rhizoctonia X X X X

Sclerotium X X X X
Vegetable/ bedding plants Rhizoctonia X X

Sclerotium X X

Beans Rhizoctonia X X

Garlic Sclerotium X X
Cole crops Rhizoctonia X X
Plasmodiophora X X87 Table 14. Alternative pesticide treatments fo r diseases controlled by PCNB (seed treatments)

Disease PCNB Triazoles Carboxides Strobilurins
Rhizoctonia damping-off X X (systemic) X (systemic) X (systemic)

Smuts and bunts X X X X
Botrytis X
Aspergillus X

Fusarium X
Rhizopus X

Penicillium X

24. Please provide any other additional, pertinent product- or formulation-specific information not anticipated by this list.
The registrants had nothing to add.APPENDIX A2. ADDENDUM TO USE CLOSURE MEMO

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES June 23, 2003

MEMORANDUM

FROM: Jill Bloom, Review Manager /s/ SRRD/Reregistration Branch 2 (7508C)

TO: PCNB RED Team

SUBJECT: Addendum to Use Closure for PCNB
This memo supplements and revises the draft Use Closure Memo for PCNB dated January 23, 2003. Crompton/Uniroyal Chemical, Amv ac Chemical, and Gustafson LLC were all asked to review the memo for accuracy with respect to their products and to provide upda ted and missing information. The revisions in this addendum are based on comments received from Crompton/Uniroyal on the memo and in subsequent communications. Gustafson provide d one general comment, that the memo correctly characterized the use of its registrations. Amvac Chem ical has not responded to the draft Use Closure Memo, but answered one specific question about reapplication, as noted below. Because Amvac did not respond comprehensively, there are a few cases in which I am not able to revise the memo to delete specific uses or application methods that Crompton/Uniroyal has indicated do not apply to its products, or to revise use rates and number of applications as suggested by Crompt on/Uniroyal, but I have noted Crompton/ Uniroyal’s claims for its own products.
SRRD does not anticipate obtaining any additional input from Amvac at this time, and recommends that the risk assessments be conducted using the availa ble information. OPP will have an opportunity to address any additional information provided by the registrants’ 30-day “error only” responses.

Uses
Crompton/Uniroyal is not aware of any use of PC NB on tobacco. In addition to the uses the January 23, 2003 memo shows that Crompton/Uniroyal is supporting through reregistration, add potatoes (in addition to potato seed piece) and the seed treatments barley, be ans, corn, cotton, oats, peas, peanut, safflower, sorghum, soybean, sugar beet, and wheat.89 Application Methods
The following application methods should be added to Table 2 in the draft memo:
For azaleas and camellias broadcast, add F, WP; for drench, add EC, F, WP. For bedding plants broadcast, add WP For calendula, etc. drench, add F, WP For cut flowers dip etc., add WP For herbaceous, etc. plants broadcast, add WP For bulbs drench, add F, WP For lily band, add G; for drench, add F, WP; for in-furrow, add WP For pine drench, add F, WP For roses broadcast, add F, G, WP; for drench, add F, WP For tropical foliage plants broadcast, add WP
In addition, Crompton/Uniroyal notes that its granular products are not used as a drench on herbaceous and woody plants; dip, direct spray, or in -furrow on bulbs; dip, direct spray on lily; dip, direct spray on roses; nor drench on tropical foliage plants..
Uniroyal adds that its products may also be applied to vegetable bedding plants (as well as ornamentals) through growth medium in corporation, and that only its flow able formulation (not granular or wettable powder formulations) may be applied to mushroom houses.
Although PCNB is mostly applied once per season, mu ltiple treatments may be made to ornamentals, as well as turf. Turf applications may also be made prior to first appearance of disease.
In response to questions about how repeat applications are made with PCNB, both Crompton/Uniroyal and Amvac supplied information. HED asked that the registrants supply information on repeat applications for the following use sites: azaleas/camellias/gardenias, beans, bulbs, magnolia, lawns/turf, ornamental bedding plants , vegetable bedding plants, field grown ornamentals. Specific instructions on reapplication for most of these sites are shown in the table below.90 Methods of Reapplication for PCNB on Selected Sites
Use site Registrant(s) How reapplied
Azalea, camellia Uniroyal Amvac first application prior to opening of buds; repeat every 3-4 weeks during blooming season; uniform coverage be neath bushes and in the plant bed
Beans (for white mold) Amvac first app lication at plant; repeat at 2-3 week intervals if disease problem is severe; 2.75 lb/A; direct spray at soil at base of plants
Bulbs Uniroyal Amvac (for bulb rot and stem rot on Dutch Iris; except for 5481-211, 400-405, 400-454, 400-457, and 400-479 which are labeled for the repeat application on bulb crops in general) first application at plant; reapply 3 more times at 15 day intervals; application method unspecified (see comments below)
Magnolia grandiflora Uniroyal foliar spray before disease typically appears, at least 4 sprays total at 2 week intervals
Lawns, turf Uniroyal Amvac repeat application every 7-10 days or 3-4 weeks or 4-6 weeks (depending on species and disease) after heavy rainfall or if disease is severe or reappears; application methods genera lly specified but not separately for repeat applications; important to water-in
Ornamental bedding plants Uniroyal Amvac one repeat application 4-6 weeks afte r initial application; various rates depending on soil depth, bench- or pot-grown; soil drench; for 400-405, 400-457 do not repeat treatment more than once in 4 months
Vegetable bedding plants Uniroyal Amvac one repeat application 4-6 weeks af ter initial application; soil drench; various rates depending depth of potting medium; soil drench
The reapplication method for bulbs is ambiguous on the labels, but Amvac states: “The way [Amvac’s] labels read the applicator would be direct ed to apply the product 3 times as a granular or liquid spray in a 12 inch band centered over the row after planti ng. This is a follow-up treatment to the at-planting application. Therefore, the products would contact both the soil around the base of the plant, as well as the plant itself. [Amvac does] not know of anyway [an app licator] could apply the products at this timing without contacting the plants, unless [the registrant] specified u se of drop tubes or nozzles th at were directed to the soil around the base of the plant.”
Crompton acknowledged that the use directions are not clear, and said: “The labels say the first application is applied over the row "at" planting time, and the title indicates this would be before planting time. With the planting operation, this would have the effect of incorporating the PCNB around the bulbs. The repeat applications are still under the "Prior to pl anting” heading, but obviously would be after planting and applied in a band over the row. This woul d probably be primarily to the soil surface, however the sprays would also contact at least the lower portion of the plants. At 15 days intervals, the 4th application (3rd repeat) would be at about 2 months , so the plants would be fairly large.
“For the 75W and 400 formulations these repeat app lications would most likely be as directed sprays to the soil and base of the plant. For the Turfcide 10G , this would be some type of granular application, probably either over the top of the plant or directed to the soil under the plant. There would be minimal PCNB stay on the plant from the 10G, because most of the granular would fall to the soil surface.”
Other sites in addition to those listed above may receive repeat treatments. Uniroyal 400-399 and 400-400 both indicate that a repeat application may be made to peanuts in general use instructions, but peanut-specific instructions say “use only at planti ng.” Amvac 5481-441 allows one repeat application on tropical foliage plants at 4-6 weeks after initial treatment; no application method is specified for the repeat91 application although the initial treatment is a soil dr ench. TX900010 (5481-212) allows repeat application on peanuts at 3 gal/A of product through overhead spri nkler irrigation 30 days after initial treatment of 2 lbs/A. TX920024 (5481-279) allows repeat applicati on on peanuts at 5 lbs/A of product through overhead sprinkler irrigation 30 days after initial treat ment of 8 lbs/A. ID000008, NV000005, OR000019, and WA000030 (5481-472) allow repeat appli cations on potatoes at 3-10 pints/A of product through irrigation (foliar) at 7-10 day intervals after initial treatment of 3-10 pints/A (not to exceed 20 lbs ai/A, or 40 pints/A).

Use Rates
Crompton/Uniroyal states that the maximum number of application for its products on beans is once/year, that the maximum number of application for its products on potatoes is once/year with a typical application rate of 2.5 lbs. ai/A, and that its maximum a pplication rate for peanuts is 2 lbs. ai/A. In addition, Uniroyal/Crompton supplied the attached table of use parameters for turf and ornamental sites–see Attachment 1.
Responses to Specific Questions
Question #8 in the draft memo reads, “For applications to trees where label rates are given as lbs of formulation per 100 gallons of water, please provide information on the number of trees treated per day by a handler and the number of gallons of diluted material per tree.” Uniroyal/ Crompton did not answer this question in its initial submission, but now indicates th at it couldn’t find any applicators with experience in this use, and so could not provide an answer. Crompton/Uniroyal had the same response to Question #9 , which asked for the same kind of information for a pplications to cut flowers with a spray or dip.
Uniroyal has also provided additional informa tion on alternatives for turf and ornamentals, in response to Question #23 –see attachment 2.

Attachments

25. Use Parameters for Turf and Ornamental Site Applications of PCNB (submitted by Crompton/Uniroyal, labeled Table II) 26. Alternative Pesticide Treatments for Diseases Controlled by PCNB (submitted by Crompton/Uniroyal, labeled “Turf & Ornamentals Information)92939495969798APPENDIX A3. QUANTITATIVE USAGE ANALYSIS FOR PCNBCase Number: 0128 Date: 10/12/2001 Analyst: Tim Kiely Data years: 1990 - 2000PC Code: 56502 Original QUA date: 01/11/99 QUAlast edited: 10/12/2001 Filename: PCNB2001.wpdBased on available pesticide survey usage information for the years of 1990 through 2000, an annual estimate of PCNB’s total domestic usage averagedapproximately 1,825,000 pounds of active ingredient (a.i.) appliedto 794,000 acres. PCNB is a fungicide with its largest markets in terms of total pounds activeingredient allocated to turf (49%) and cotton (27%). The crops with the highest percentage of their total U.S. planted acres treated with PCNB is Brussel Sprouts(13%), cotton (5%), and potatoes (3%). No other crop has more than 2% of their acreage treated with PCNB. Please see Table 1for estimates of usage by site.Table 1. Estimates of PCNB Usage by site.Site AcresGrown(000)Acres Treated(000)% of CropTreatedPounds AIApplied(000)Average Application Rate States of Most UsageWtdAvgEstMaxWtdAvgEstMaxWtdAvgEstMaxlb ai/acre/yr#appl/ yrlb ai/A/appl(% of total lb ai usedon this site)Apples 572 0* 0* 0* 0* 0* 0* -- -- -- --Pears 71 0* 0* 0* 0* 0* 0* -- -- -- --Bananas -- -- -- -- -- -- -- -- -- -- --Strawberries 47 0* 0* 0% 0% 0* 0* -- -- -- --Garlic 40 0 0 0% 0% 0 0 -- -- -- --Onions, Dry 140 0 0 0% 0% 0 0 -- -- -- --Eggplant/Peppers 121 2 4 2% 3% 4 8 1.8 1.5 1.2 NM NJ 100%Cole Crops /1 303 3 5 1% 2% 16 32 6.1 1.0 6.1 OR WA OH CA AZ 91%Site AcresGrown(000)Acres Treated(000)% of CropTreatedPounds AIApplied(000)Average Application Rate States of Most UsageWtdAvgEstMaxWtdAvgEstMaxWtdAvgEstMaxlb ai/acre/yr#appl/ yrlb ai/A/appl(% of total lb ai usedon this site)99- Mustard, greens 9 0* 0* 0% 0% 0* 0* -- -- -- --- Broccoli 126 1 2 0% 1% 2 4 3.6 1.0 3.6 CA 100%- Brussels Sprouts 4 0 1 13% 17% 10 20 22.2 1.5 14.8 CA 100%- Cabbage 82 1 1 1% 2% 1 1 0.7 1.0 0.7 NC WA OR 97%- Chinese Cabbage 12 -- -- -- -- -- -- -- -- -- --- Cauliflower 53 1 2 2% 3% 3 7 3.7 1.0 3.7 CA 85%- Collards 14 0* 0* 0% 0% 0* 0* -- -- -- --Kale 4 0* 0* 0% 0% 0* 0* -- -- -- --Broccoli, Chinese -- -- -- -- -- -- -- -- -- -- --Beets -- -- -- -- -- -- -- -- -- -- --Cucurbits /2 288 1 2 0% 1% 1 4 0.9 1.4 0.6 SC, GA, NC 93%Lettuce 309 0* 0* 0% 0% 0* 0* -- -- -- --Potatoes 1,420 45 65 3% 5% 180 260 4.0 1.0 4.0 --Tomatoes 477 0 1 0% 0% 1 2 2.2 1.0 2.2 FL CA 100%Site AcresGrown(000)Acres Treated(000)% of CropTreatedPounds AIApplied(000)Average Application Rate States of Most UsageWtdAvgEstMaxWtdAvgEstMaxWtdAvgEstMaxlb ai/acre/yr#appl/ yrlb ai/A/appl(% of total lb ai usedon this site)100Beans/Peas, Dry 2,237 0 1 0% 0% 0 1 0.8 1.0 0.8 WA 90%Beans/Peas, Green 708 15 20 2% 3% 15 20 1.0 1.1 0.9 FL GA NJ NC MD MS 85%Corn 71,433 0* 0* 0% 0% 0* 0* -- -- -- --Barley 8,190 0* 0* 0% 0% 0* 0* -- -- -- --Rice 3,175 0 0 0% 0% 0 1 2.0 1.0 2.0 AR 100%Wheat 71,464 1 3 0% 0% 0 1 0.5 1.0 0.5 AR DE 100%Soybeans 66,533 4 18 0% 0% 6 25 1.5 1.3 1.1 MS AR TN 88%Cotton 13,232 700 1,200 5% 9% 490 840 0.7 1.0 0.7 MS AR LA TN AL NC 80%Peanuts 1,515 10 23 1% 2% 17 36 1.7 1.2 1.4 TX GA OK AL AZ 81%Sugar Beets 1,434 0 2 0% 0% 0 1 1.0 1.0 1.0 MT CA 83%Tobacco 712 10 22 1% 3% 9 20 0.9 1.0 0.9 NC VA 84%Clover -- -- -- -- -- -- -- -- -- -- –Ginseng -- -- -- -- -- -- -- -- -- -- –Site AcresGrown(000)Acres Treated(000)% of CropTreatedPounds AIApplied(000)Average Application Rate States of Most UsageWtdAvgEstMaxWtdAvgEstMaxWtdAvgEstMaxlb ai/acre/yr#appl/ yrlb ai/A/appl(% of total lb ai usedon this site)101Coffee -- -- -- -- -- -- -- -- -- -- --Turf /3 -- -- -- -- -- 900 1,150 -- -- -- --Ornamental Plants /4 -- -- -- -- -- 45 70 -- -- -- --Seed Treatment /5 -- -- -- -- -- 125 200 -- -- -- --Total 794 1,082 1,825 2,263NOTES ON TABLE DATA- Usage data primarily covers 1990 - 2000.- Wtd Avg = Weighted average--the most recent yearsand more reliable data are weighted more heavily.- Est Max = Estimated maximum, which is estimated from available data.- Average application rates are calculated from the weighted averages.- Calculations of the above numbers may not appear to agreebecause they are displayed as rounded to the nearest 1000 for acrestreated or lb. a.i. (therefore 0 = < 500) and to the nearest wholepercentage point for % of crop treated (Therefore 0% = < 0.5%).- 0* = Available EPA sources indicate that no usage is observed inthe reported data for this site, which implies that there is little or no usage.- A double dash (--) indicates that information on this siteis NOT available in EPA sources or is insufficient.1. Cole Crops include broccoli, Brussels sprouts, cabbage, cauliflower, mustard greens, collards and Chinese cabbage.2. Cucurbits includes cucumber, squash and pumpkins.3. Turf includes golf courses, sod farms, and lawn care operators (with applications to residential turf and gardens).4. Ornamentals include nurseries and greenhouses.5. Seed Treatment includes barley, corn,cotton, peanut, pea, sorghum, soybean, oats, safflower, sugar beet, wheat, rice.Sources: EPA proprietary data, USDA National Agricultural ServiceChemical Use Reports, California Department of Pesticide Regulation Pesticide Use Database, and National Center for Foodand Agricultural Policy pesticide use database.102

### 103 APPENDIX B. ENVIRONMENTAL FATE DATA
Abiotic Degradation
Hydrolysis
Pentachloronitrobenzene (PCNB) is stable to hydr olysis at environmentally relevant pH’s and temperatures. In two separate studies conducted for 30 days in darkness at 25°C, PCNB (at 0.3 ppm) did not hydrolyze in sterile pH 5, 7 and 9 aqueous buffer solutions (MRID’s 40865301, 40972601). The submitted studies were both classified as acceptable and provi de adequate data for the risk assessment.
Aqueous Photolysis
PCNB is rapidly photodegraded in water under fa vorable light conditions. Two separate guideline studies were submitted. In one study, [U- 14 C]PCNB, at 0.075 ppm, photodegraded with a half-life of approximately 27 hours (corrected for continuous irradi ation conditions) in sterile pH 5 aqueous buffered solution maintained at 25°C and irradiated with a xenon lamp for 32 hours (MRID 42336201). In that study, it was determined that the majority of residues were chlorinated hydroxybenzenes and/or chloronitrophenols, but trihydroxydichloronitrobenzene was the only com pound tentatively identified. In the second study, [U-
14 C]PCNB, at 0.1 ppm, photodegraded with a half-life of 2.5 days in sterile pH 5 aqueous buffered solution maintained at 25°C and irradiated continuously (at half the intensity of natural sunlight) with a xenon lamp for 7 days (MRID’s 42606201, 42606202). Two major degradates, present at maximums of 26.3% and 20.5% of the applied, were isolated but were not identified. Additional analysis indicated that the two unidentified degradates were high molecular weight polar compounds which did not retain the benzene ring. Based on the results of the studies, photodegradation is expected to be a significant route of dissipation for PCNB in the environment when the compound is present in clear, shallow surface water in a non-adsorbed state. The two photodegradation studies were classified as acceptabl e and provide useful data for the risk assessment. The identification of the photoproducts of PCNB would pr ovide additional useful information for future risk assessments.
Soil Photolysis
PCNB photodegrades slowly on soil. Two separate guideline studies were submitted. In the first study, [ 14 C]PCNB degraded with a half-life of 80 days on sandy loam soil maintained at 25°C and irradiated with a xexon lamp for 30 days (MRID’s 41004801, 41713201) . No major degradates were detected; two minor degradates present at # 4% of the applied were not identified d espite additional analysis. The half-life reported in the study is of questionable value, as it was ex trapolated beyond the scope of the data. It is useful, however, in that it indicates that photodegradation of PCNB on soil will be a relatively slow process. This study was classified as acceptable and provides some useful data for the risk assessment.
In the second study, [ 14 C]PCNB, applied to sandy loam soil at 9.6 ppm, was photodegraded when maintained at 75% of 0.33 bar moisture content and irradiated with a xenon lamp for approximately 12 hours/day for 30 days at 25 °C (MRID 42841106; apparently also resubmitted as MRID 42911901). There were no major degradates; the minor degradates identified in the study (in both the irradiated and dark control soils) were pentachloroaniline (PCA ); pentachlorothioanisole (PCTA); pentachlorothioanisole sulfoxide (PCTASO); and pentachlorothioanisole sulfone (PCTASO 2 ). The half-life determined in the second study is not useful, however, as the material balance was unacceptable, with up to 35% (irradiated soils) and 15% (dark controls) of the applied radioactivity not account ed for by the end of the study. This study was

### 104 classified as nonacceptable (in reviews of both MRID’s ) and does not provide adequate data for the risk assessment.

Metabolism

Aerobic Soil Metabolism
PCNB is metabolized slowly in aerobic soil. The biodegradation of PCNB in aerobic soil was studied in multiple soils; two separate guideline studies were submitted. Based on the results of the studies, microbially mediated metabolism of PCNB in aerobic soil is expected to proceed slowly in the environment.
In one study, [ 14 C]PCNB, at 10 ppm, dissipated (degradation pl us volatilization) with an initial halflife (days 0-30) of 30 days in aerobic sandy loam soil that was incubated in the dark at 25 ± 1°C for 1 year (MRID 42911902). After this initial period, very little further degradation was observed (second phase DT 50 : 316 days). When the complete data set is used, the first-order half-life is estimated at 189 days; this value will be used in the risk assessment. By the end of the study, volatiles (mainly PCNB, with some PCTA, PCA, PCB and CO 2 ) accounted for 33.7% of the applied; at the time the half-life (189 days) occurred, volatiles accounted for 23.0-28.3% of the applied. None of the degradates were detected at $ 10% of the applied. The five minor degradates identified in the soil were pentachloroaniline (PCA; maximum of 0.91 ppm), pentachlorothioanisole (PCTA; maximum of 0.81 ppm), pentachlorothioanisole sulfoxide (PCTASO; maximum of 0.37 ppm), pentachlorothioanisole sulfone (PCTASO 2; maximum of 0.61 ppm), and pentachlorobenzene (PCB; maximum of 0.27 ppm). All five degradates appeared to be stable in soil. The potential degradate PCP was not detected in study samples. This study was classified as acceptable and provides adequate data for the risk assessment.
In the second study, [ 14 C]PCNB, at 10.5 ppm, dissipated (degradation plus volatilization) with a halflife of 77 days in aerobic sandy loam soil that was in cubated in the dark at 25 °C for 1 year (MRID’s 41384501, 41713202, 42112801). By the end of the study, vol atiles (mainly PCNB, with some PCA and minimal CO 2 ) accounted for 60.5% of the applied; at the time the half-life (77 days) occurred, volatiles accounted for 8.9-16.6% of the applied. The major degradate identified in th e soil was pentachloroaniline (PCA; maximum of 12.9% of the applied). One minor degradate, pentachlorothioanisole (PCTA; maximum of 1.9%), was identified in the soil. The potential de gradate PCP did not appear to be monitored in study samples. This study was classified as acceptable and provides adequate data for the risk assessment.
For the purposes of the water resources assessment, a nd in response to a decision made by the MARC committee, the half-lives were recalculated using c oncentration data for the parent compound plus the degradate PCA. The recalculated aerobic soil metabolis m half-lives for the parent/PCA combination are 489 days (r 2 = 0.54; MRID 42911902) and 1012 days (r 2 = 0.53; MRID’s 41384501, 41713202, 42112801); these are the values that will be used to determine estimateddrinking water concentrations (EDWC’s). While the MARC committee also decided that pentachlorophenol (PCP) was a degradate of interest and should be included in the water resources asses sment, the compound was not detected in either of the aerobic soil metabolism studies. For the determination of the estim ated environmental concentrations (EEC’s) for use in ecological risk assessment, the half- lives were recalculated using “total residues” (defined here as including only the following compounds: PCNB, PCA, PCTA, PCB, PCP, PCTASO, PCTASO 2 and/or HCB). The recalculated aerobic soil metabolism half-lives for total residues are 983 days (r 2 = 0.50; MRID 42911902) and 1052 days (r 2 = 0.53; MRID’s 41384501, 41713202, 42112801); these are the values that will be used in the determining EEC’s for the ecological risk assessment.

### 105 Anaerobic Soil Metabolism
PCNB is metabolized more rapidly in anaerobic soil than in aerobic soil. The biodegradation of PCNB in anaerobic soil was studied in multiple soils ; two separate guideline studies were submitted. Based on the results of the studies, microbially mediated metabolism of PCNB in anaerobic soil is expected to proceed moderately rapidly in the environment. Howe ver, the major degradate, PCA, appears to be stable to further degradation.
In one study, [ 14 C]PCNB, at 25 ppm, dissipated (degradation plus volatilization) with an observed DT 50 of <30 days in anaerobic sandy loam soil that was incubated under anaerobic conditions (flooding, nitrogen) in the dark at 25 °C for 60 days afte r being incubated aerobically for 30 days (MRID’s 41203602, 42094401). Post-flooding sampling intervals were inadequa te to accurately establish the half-life; flooded soils were sampled only at 60 and 90 days (30 and 60 days post-flooding). Of the residues recovered (approximately 96% of the applied at each sampling interval) at 60 and 90 days post-flooding, 78.5-79.5% were detected in the soil phase of the test system, 2.6-3.1% were in the water phase, and 9.2-10.5% were present as volatiles. PCNB was present in the soil at 9.65 ppm immediately post-flooding and decreased to 0.643 ppm and 0.627 ppm, respectively, following 30 and 60 days of anaerobic incubation. The major degradate PCA was present in the soil at a maximum of 13.8 ppm (30 days post-flooding). The minor degradates detected were PCTA, present in the so il during the anaerobic phase at a maximum of 0.57 ppm (immediately pre-flooding), and pentachlorophenol (PCP), present in the soil at a maximum of 0.33 ppm (60 days post-flooding). In the water phase, PCNB was not detected at 60 days, but was 0.028 ppm at day 90. The degradate PCA was present in the water at a maxi mum of 0.16 ppm (day 90). The degradate PCP was present in the water at 0.048 ppm at day 60 and 0.037 ppm at day 90. By the end of the aerobic incubation period (30 days), volatiles accounted for 1.3 ppm; by the end of the anaerobic incubation period, they accounted for 2.2 ppm. PCNB and PCA accounted for the ma jority of the volatiles at all intervals, with PCB and HCB detected only at 30 days and in small am ounts (2.7% and 1.9% of total volatiles, respectively) relative to PCNB and PCA. This study was classifi ed as acceptable and provides some useful information for the risk assessment. However, the half-life value is imprecise (due to sparse data). Additional data on the anaerobic metabolism of PCNB, particularly w ith regard to the degradate PCP, are necessary to adequately assess the environmental fate of the compound. It would be more useful, given current modeling requirements, to have data from anaerobic aquatic me tabolism studies rather than from additional anaerobic soil metabolism studies.
In the second study, [ 14 C]PCNB, at 10.47 ppm, dissipated (degradation plus volatilization) with a calculated half-life of 9 days in anaerobic sandy loam soil that was incubated under anaerobic conditions (flooding, nitrogen) in the dark at 25 °C for 60 days after being incubated aerobically for 30 days (MRID’s 41384301, 41686001, 41713203, 42112802). However, post-floodi ng sampling intervals were inadequate to accurately establish a valid half-life; flooded soils were sampled only at 60 and 90 days (30 and 60 days post-flooding). Of the residues recovered (approximately 96% and 91.2% of the applied, respectively) at 60 and 90 days post-flooding, 83.8-90.3% we re detected in the soil phase of the test system, 1.6-1.7% were in the water phase, and 4.2-5.8% were present as volatil es. PCNB was present in the flooded soil system at 71.4% of the applied immediately post-flooding and d ecreased to 1.3% and 0.7%, respectively, following 30 and 60 days of anaerobic incubation. The major degradate PCA was present at a maximum of 70.3% of the applied (day 60; 30 days post-flooding) and was still 66.5% at day 90. The minor degradate PCTA was present at a maximum of 1.9% of the applied (day 30). By the end of the aerobic incubation period (30 days), volatiles accounted for 3.2% of the applied; by the end of the anaerobic incubation period, they accounted for 5.8%. PCNB and PCA accounted for the majority of the volatiles at all intervals, with an unidentified compound detected at 3-30 days at 4.8-7.4% of the radio activity detected in the ethylene glycol volatile trap

### 106 (which was only 0.1-3.2% of the applied at 3-30 days). This study was classified as acceptable (prior to current modeling requirements) and provides some useful information for the risk assessment. However, the half-life value is imprecise (due to sparse data). Also, despite further analysis, radioactivity detected at the origin of the TLC plates (maximum of 7% of the applied) could not be fully identified. Based on the information reported in the study, the degradate PCP (notably found in the first anaerobic metabolism study) was not monitored in this study as a potential degr adation product. Additional data on the anaerobic metabolism of PCNB are necessary to adequately assess the environmental fate of the compound.
For the purposes of the water resources assessment, a nd in response to a decision made by the MARC committee, the half-lives were recalculated using c oncentration data for the parent compound plus the degradate PCA. The recalculated anaerobic soil metabo lism half-life for the parent/PCA combination is 410 days (r 2 = 0.92; MRID’s 41384301, 41686001, 41713203, 42112802); this is the source data value that will be used to determine estimated drinking water concentr ations (EDWC’s). A half-life could not be calculated using the data in MRID’s 41203602 and 42094401, as the concentration data (PCNB plus PCA) showed apparent increases over time. The data reporting for the study was both unclear and insufficient. Data were reported as “percent distribution” and as percentages of the recovered radioactivity (which varies with each sampling interval and test system phase) rather than in a straightforward manner such as in percentages of the applied or in units of concentration for each i ndividual compound in each phase (i.e., soil, water or air) of the test system. However, the data are somewhat useful in that they indicate the stability of the compounds (in combination) to anaerobic degradation. For the determination of the estimated environmental concentrations (EEC’s) for use in ecological risk assessm ent, the half-lives were recalculated using “total residues” (defined here as including only the followi ng compounds of interest: PCNB, PCA, PCTA, PCB, PCP, PCTASO, PCTASO 2 and/or HCB). The recalculated anaerobic soil metabolism half-life for total residues is 334 days (r 2 = 0.89; MRID’s 41384301, 41686001, 41713203, 42112802); this is the source data value that will be used to determine EEC’s for the ecological risk assessment. A half-life could not be calculated using the data in MRID’s 41203602 and 42094401. As with the PCNB plus PCA half-life determination, it was found that the concentration data (total residues) showed apparent increases over time.

Mobility and Persistence
Adsorption/Desorption
Based on soil adsorption coefficient (K d ) values determined using Freundlich adsorption isotherms with batch equilibrium study data, PCNB is expected to have slight to moderate mobility in some soils, particularly in coarse soils that are low in organic matte r, and to be immobile in most others; thus, it is also generally expected to bind to aquatic sediments as we ll as to organic matter in the water column. Based on soil adsorption coefficient (K d ) values determined using Freundlic h adsorption isotherms with batch equilibrium study data, the major degradates pentach loroaniline (PCA) and pent achlorothioanisole (PCTA) are expected to be immobile in soil. Three separ ate mobility studies (two batch equilibrium, one column leaching) were submitted for the parent compound. Single studies (batch equilibrium) were submitted for the degradates PCA and PCTA.
Soil characteristics and adsorption/desorption study results (batch equilibrium only) for PCNB are presented in Table B1 . In the first study, the adsorption of PCNB was studied in four soils treated with PCNB at five concentrations ranging from 0.006 to 0.172 μg/mL and maintained in darkness at 25 o C for four hours (MRID 41648201). After the equilibration period, adsorption of PCNB was 25.0-90.8%. The adsorption K values were 7.3-210 mL/g; adsorption K oc values were 1588-17508. Desorption, following

### 107 overnight equilibration, was 6.31-94%. The deso rption K values were 0.49-1.11 mL/g; desorption K oc values were 1208-9758. This study was classified as acceptable and provides adequate data on the parent compound for use in the risk assessment.
In the second study, the adsorption of PCNB was st udied in four soils treated with PCNB at only three concentrations ranging from 0.25 to 1. 26 ppm and maintained in darkness at 25 o C for 24 hours (MRID 00114168). Desorption was not studied. The adsorp tion K values were 64-1750 mL/g and adsorption K oc values were 6966-150,862. This study was supplemental and provides some useful information for the risk assessment, although the adsorption K values will not be used in modelling to estimate environmental concentrations in water. The adsorption of PCNB was studied using only three concentrations (four are necessary for the valid use of Freundlich isotherms) and it was not established in the study that the systems had reached equilibrium or that the test compound was completely dissolved in the calcium sulfate solution. The high treatment level (1260 ppb) was well above the solubility limit in water (440 ppb). Also, desorption was not studied. It is notable that all of the soils studi ed were acidic, with pH values of 4.7, 4.8, 5.0 and 5.7.
Table B1. Freundlich adsorption and desorp tion constants for PCNB in eight soils.

Soil type (% organic carbon; pH) Adsorption Desorption
K (mL/g) 1/n r 2 K oc K (mL/g) 1/n r 2 K oc silt loam (1.2%, pH 7.1) 1 19.1 0.83 0.98 1588 25.9 0.89 0.98 2161

clay (1.2%, pH 6.7) 1 210 1.06 0.97 17508 117.1 0.88 0.99 9758
sandy loam (0.4%, pH) 6.5) 1 15.5 0.87 0.93 3870 4.8 0.49 0.92 1208

sand (0.25%, pH 7.4) 1 7.3 0.9 0.89 2912 20.1 1.11 0.38 8044
sand (0.52%, pH5.7) 2 64.5 0.91 NR 3 12356

———— sandy loam (0.87%, pH 4.8) 2 64.1 1.15 NR 3 7368

————

silt loam (1.45%, pH 4.7) 2 101 0.94 NR 3 6966

————

silt loam (1.16%, pH 5.0) 2 1750 0.67 NR 3 150862

————

1 Data obtained from MRID 41648201. 2 Data obtained from MRID 00114168; study did not address desorption and adsorption values will not be used in the risk assessment due to expe rimental methodology shortcomings. 3 NR = not reported. A third study (MRID 400114181) conducted using leach ing columns was found to be supplemental and provides limited useful data for the risk assessment. [ 14 C]PCNB, at 5.72 ppm, was relatively immobile in two silt loam soils, a sand soil and a sandy loam soil in unaged soil columns, with 74.8-84.5% of the applied detected in the top 5-cm layers following leachi ng. In the 5- to 10-cm layer, PCNB was detected at 4.0-16.5% of the applied; <1.12% was detected below 10 cm. In aged soil columns (silt loam and sandy loam soils only), PCNB exhibited similar mobility. A total of 3.5-5.9% of the applied was detected at 5-10 cm. The degradates PCA and PCTA were detected at 3.1% a nd 0.46% of the applied, respectively, in the top 5-cm layer of the sandy loam soil column. [ 14 C]PCNB was not detected in the leachate from any of the columns. The study was sound to be supplementa l due to insufficient data reporting.
The adsorption of the degradate PCA was studied in four soils (sand, sandy loam, silt loam, and silty clay loam) treated with PCA at four concentrati ons ranging from 0.05 to 0.20 μg/mL and maintained in

### 108 darkness at 22.5 o C for 24 hours (MRID 43500502). The respective adsorption K values were 37, 78, 39, and 117; corresponding K oc values were 3337, 7116, 3581, and 10580. Desorption K values were 90 for the sand soil, 122 for the sandy loam soil, 42 for the s ilt loam soil, and 160 for the silty clay loam soil; corresponding K oc values were 8158, 11025, 3800, and 14533. The 1/N values ranged from 0.78 to 0.86 for adsorption and from 0.85 to 1.03 for desorption. The study is acceptable and provides adequate data on the degradate PCA for use in the risk assessment.
The adsorption of the degradate PCTA was studied in four soils (sand, sandy loam, silt loam, and silty clay loam) treated with PCTA at four concentra tions ranging from 0.05 to 0.20 μg/mL and maintained in darkness at 22.5 o C for 24 hours (MRID 43500501). The respective adsorption K values were 205, 214, 503, and 411; corresponding K oc values were 18610, 19395, 45662, and 37267. Desorption K values were 202 for the sand soil, 262 for the sandy loam soil, 244 for th e silt loam soil, and 630 for the silty clay loam soil; corresponding K oc values were 18299, 23730, 22176, and 57168. The 1/N values ranged from 0.89 to 1.26 for adsorption and from 0.93 to 1.06 for desorption. The study is acceptable and provides adequate data on the degradate PCTA for use in the risk assessment.
Laboratory Volatility
Based on laboratory studies of the volatility of PCNB, the compound is expected to be volatilized from soil. Two separate studies were submitted. In one study, the volatility of PCNB from soil was studied using PCNB that was incorporated into sandy loam soil which was incubated at 25 o C in darkness at 50% or 75% of field moisture capacity. Airflow through the system was 283-311 mL/min. PCNB, at 20 ppm, volatilized from soil at a range of 0.0622-0.171 μg/cm 2 /hr (MRID 41178001). The calculated vapor pressure was a range of 3.14-8.19 x 10 -5 mmHg and the vapor density was a range of 4.99 x 10 -4 to 1.30 x 10 -3 g/m 3

. At 7 days posttreatment, volatilized PCNB was a tota l of 1556-1650 μg (approximately 80% of the applied); no other volatile compounds were detected. The st udy was determined to be acceptable and provides adequate data for the risk assessment.
In the second study, the volatility of PCNB from soil was studied at 25 o C (in darkness for 15 days) using PCNB (formulated as Terraclor) applied to soil wh ich had been previously moistened to 75% of field capacity. The maximum volatilization rates were 4.31 x 10 -3 μg/cm 2 /hr for airflow at 50 mL/min and 6.08 x 10 -3 μg/cm 2 /hr for airflow at 150 mL/min (MRID 42507401). Maximum volatilization occurred within 24 hours of treatment. The vapor pressure of PCNB was reported to be 9.5 x 10 -5 mmHg at 25 o C. The study was determined to be acceptable and provi des adequate data for the risk assessment.
Field Volatility
Based on a field study of the volatility of PCNB applied to soil, the compound is expected to be volatilized from soil when applied by ground spray in a banded row. PCNB (as Terraclor 75% WP), at 10.2 lb ai/A, volatilized from an unvegetated silt loam soil inMississippi; approximately 65% of the total volatiles trapped were collected during the first two days of the study. Volatilized PCNB was at a maximum on day 0 and declined throughout the rest of the 13-day study . Total volatilized PCNB trapped by Lo-Vol filters ranged from 21.45 to 67.49 ng/liter during the four 2- hr sampling times on day 0, was 17.59-27.26 ng/liter on day 1, decreased to 3.37-4.41 ng/liter by day 5, and was 1.40-1.56 ng/liter on day 13. The majority of the PCNB trapped by Lo-Vol filters was at the 15-cm height, with decreasing amounts at 40, 70, and 150 cm. The total amount of PCNB trapped by on Hi-Vol f ilters was 6.12-18.64 ng/liter on day 0, 2.69-5.36 ng/liter on day 1, 0.55-1.14 ng/liter on day 5 and 0.21-0.33 ng/liter on day 13. The degradate PCA was also detected as a volatile. Total PCA volatilized was at a maximum on day 0 and declined throughout the rest of the study.

### 109 Total PCA trapped by the Lo-Vol filters ranged from 3.32 to 9.61 ng/liter during the four 2-hr sampling times on day 0 of the study, was 3.18-4.01 ng/liter at day 1, decreased to 0.74-1.26 ng/liter by day 5, and was 0-0.41 ng/liter on day 13. The majority of the PCA trapped by the Lo-Vol filters was at the 15 cm height, with decreasing amounts at 40, 70, and 150 cm. The total amount of PCA found on Hi-Vol filters was 0.63-1.78 ng/liter on day 0, 0.23-0.47 ng/liter on day 1, 0.02-0.07 ng/liter on day 5 and 0-0.03 ng/liter on day 13. This study was found to be acceptable and provides useful data on the volatility of banded row-applied PCNB from bare ground soil for the risk assessment. However, it is noted that the observed volatilization in the study may underestimate that which might have occurre d in the field under different weather conditions. As over five inches of rain fell in the study area (precluding air sampling on days 4 and 9) from days 3 to 9, the observed volatilization cannot be considered to be re presentative of that which might occur over time under more typical field conditions or in more arid regions, but the results are useful in that they indicate that volatilization can be expected to occur in the field.
Terrestrial Field Dissipation

Based on the results of the submitted terrestrial fi eld dissipation studies, PCNB is generally expected to be persistent in the field. The terrestrial field dissipation of PCNB was studied in three bare ground plots and five cropped plots at U.S. sites. Field study in formation and half-life and leaching results are presented in Table B2 . The half-lives (272 and 459 days) determined in two of the bare gr ound plot studies were of questionable value due to high data variability. In th e third bare ground plot (under treatment conditions for peanuts), the calculated half-life of PCNB was 57 days, although the (observed) DT 50 was less than 30 days

. Half-lives determined in the cropped plots (two in turf, two in potatoes, one in broccoli) ranged from 35 days (in turf) to 324 days (in potatoes). Dissipation was more rapid in the plots in which the pesticide was not incorporated, with a half-life range of 39-57 days vers us a half-life range of 128- 324 days (excluding the two half-life values of questionable validity) for plots with incorporated PCNB. In general, PCNB did not leach below the 6- to 12-inch soil depth. The degradates PC A, PCTA and PCB generally remained in the 0- to 6- inch soil depth, although PCA and PCB leached into the 6- to 12-inch soil depth at some sites. The degradates PCP, PCTASO and TCTSOO were detected at only one site, where they remained in the 0- to 6- inch soil depth. However, the potential degradate PCP was not monitored in most of the studies. Additional studies, not summarized below, were also s ubmitted. MRIDs 41313501 and 41747001 were classified as not acceptable. MRID 41752201 was reviewed and found not to contain sufficient information to upgrade MRID 41313501. The reviewer was unable to obtain information on MRID 44604501.
In one field study, PCNB 10G, applied at 212 lb ai/A to a bare ground loamy sand soil plot in Madera, CA, dissipated slowly with a half-life of 272 days (r2 = 0.20; MRID 43887401). However, the data exhibited high temporal and inter-replicate variability. In the 0-6" soil depth, PCNB was 165 (range of 89- 245) ppm on day 0, 123 ppm on day 1, 89 (range of 44-170) ppm on day 14, 82-86 ppm (range of 36-158) on days 119-210, and 49 ppm on day 241. At 6-12 inches, PCNB was a maximum at 90 days (mean of 1.319 ppm; replicate values of <LOQ, 3.93 ppm and 0.017 ppm) and ranged from 0.011-0.192 ppm, without a clear pattern, on days 150-241. PCNB was not detected belo w the 6-12" soil layer, except for one sampling at 14 days (0.058 ppm at 12-18"). The degradates PCB, PCA, and PCTA increased throughout the study in the 0- 6" layer. At 241 days, PCB was 0.075 ppm, PCA was 0.77 ppm, and PCTA was 0.20 ppm. The contaminant HCB was a maximum of 0.038 ppm on day 0. PCB and PCA were not detected below 6-12" and HCB and PCTA were not found below 6". The analytical method utilized did not allow for the detection of the potential degradate PCP. This study is classified as s upplemental. The half-life is of questionable validity due to the high temporal and inter-replicate data vari ability. The observed variability may be due, in part, to use of the granular formulation. However, the study does provide some useful information on leaching and general persistence of the parent compound.

### 110 In the second field study, PCNB 10G, applied at 232 lb ai/A to a bare ground sandy loam soil plot in Oglethorpe County, GA, dissipated with an estim ated half-life of 459 days (excluding day 269 data; r 2 = 0.14; MRID 43887402). However, the da ta exhibited high temporal and in ter-replicate variability. In the 0-6" soil depth, PCNB was 142 ppm on day 0, 139 ppm on day 1, 144 ppm on day 30, 104 ppm on day 120, 101 ppm on day 180, and 104 ppm on day 239. On day 269, the last day of sampling, PCNB was at a maximum for the study at 180 ppm. No explanation was given for this anomaly. At 6-12 inches, PCNB was at a maximum at 14 days (1.05 ppm). Although PCNB was found sporadically at lower depths, the pattern of detections does not indicate that PCNB was leached; it is likely that contamination occurred during the coring process. The degradates PCB, PCA, and PCTA increased throughout the study in the 0-6" layer. At 269 days, PCB was 0.24 ppm, PCA was 2.5 ppm, and PC TA was 0.73 ppm. The contaminant HCB was 0.03 ppm on days 0-30, was <LOQ on days 59-209, and w as 0.025 on day 239. On day 269, HCB was at a maximum of 0.07, but as is thought to be the case with PCNB, this was likely an error since HCB is a manufacturing impurity, not a degradate, and would not be expected to be at a higher concentration on the last day of the study versus day 0. HCB was not detected below the 0-6" layer. PCB and PCTA were detected below 0-6" only once (PCB: 0.006 ppm, 6-12" , day 269; PCTA: 0.01 ppm, 6-12", day 180). At 6- 12", PCA was detected at 0.01-0.02 ppm on days 14- 269, except for day 90 (<LOQ) and day 149 (0.06 ppm). PCA was not found below the 6-12" segment. The analy tical method utilized did not allow for the detection of the potential degradate PCP. This study is classifi ed as supplemental. The half-life is of questionable validity due to the high temporal and inter-replicate data variability. The observed variability may be due, in part, to use of the granular formulation. Howe ver, the study does provide some useful information on leaching and general persiste nce of the parent compound.
In the third field study, PCNB (pentachloronitrobenzene; Terraclor 10G, 10% granular), at 10 lb ai/A, dissipated from the 0- to 6-inch depth of unvegetated loamy sand soil in Georgia with a half-life of 57 days (MRID 43061501). However, the (observed) DT 50 was less than 30 days. In the 0-6" soil depth, PCNB was 59.5 ppm on day 0, 47.1 ppm on day 3, decreased to 27.1 ppm by day 7, then increased to 34.7 by day 14, was 18.4 ppm at 30 days, decreased to 7.8 ppm by 60 days, was 1.5-2.5 ppm at 158-270 days, and was 0.04 ppm at 535 days. The observed variability may be due, inpart, to use of the granular formulation. The degradate pentachloroaniline (PCA) was present at a maxi mum of 9.24 ppm at day 1, and remained in the range of 0.22-0.29 ppm at 158-535 days . The degradate pentachlorothioanisole (PCTA) was detected at a maximum of 0.14 ppm (120 days). The degradate pe ntachlorobenzene (PCB) was detected at a maximum of 0.03 ppm (158 days). The degradate pentachlorothioanisole sulfoxide (PCTASO)was detected at a maximum of 0.07 ppm (270 days). The degradate tetrachlorothioanisole sulfone (TCTASOO) was detected at a maximum of 0.013 ppm (460 days). The degradate pentachlorophenol (PCP) was detected at 0.022 ppm at day 0, increased with time to a maximum of 0.16 ppm by 14 days, then decreased to 0.004 ppm by 90 days, and was below the LOQ for the remainder of the study with the exception of 0.006 ppm at 270 days. The manufacturing contaminant hexachlorobenzene (HCB) was detected at a maximum of 0.047 ppm and was not detected above the LOQ by 120 days. PCNB did not leach below the 12-inch soil depth; its degradates did not leach below the 6-inch soil depth. This study is classified as acceptable and provides useful data for the risk assessment.
In the fourth field study, PCNB 2-EC, applied as a pre-emergent at 25 lb ai/A to a potato plot of loam soil in Minnesota, dissipated with a half-life of 324 days (MRID 41721401). The pesticide was incorporated to the 4- to 6-inch depth immediately after applica tion. Total PCNB residues (parent plus PCA and PCTA) dissipated with a half-life of 436 days. PCNB was det ected at 9.1 at day 0, was 4.4-4.5 ppm at 316 and 365 days, was 1.4 ppm at 456 days, and was 3.3 ppm at 515 days. The degradate PCA was a maximum of 1.1 ppm at 515 days. The degradate PCTA was a maximum of 0.25 ppm at 125 and 295 days. PCNB and its degradates were not detected below the 12-inch soil depth. The manufacturing contaminant

### 111 hexachlorobenzene (HCB) was not detect ed at any sampling interval or depth. This study is classified as acceptable and provides useful data for the risk assessment.
In the fifth field study, PCNB 75W, applied at 36 lb ai/A to a turfgrass plot of sandy loam soil in Porterville, CA, dissipated with a half-life of 19 days in soil and 17 days in turf (MRID 43887403). However, the DT 50 (observed) for dissipation in soil was between 30 and 60 days, while the DT 50 for turf was <1 day. In the soil, PCNB was observed to increase by days 1 and 14 relative to time 0. Sampling intervals for turf were inadequate, as a greater than 50% decrease in PCNB was observed between the day 1 and day 14 (the next) sampling times. In the 0-6" soil depth, PCNB was 6.6 ppm on day 0, increased to 9.5 ppm on day 1, was 8.2 ppm on day 14, 6.6 ppm on day 30, 3.2 ppm on day 59, 1.3 ppm on day 90, 0.24 ppm on day 120, 0.12 ppm on day 149, and <0.01 ppm on days 180 and 209. At 6-12 inches, PCNB was 0.034 ppm at 0 days (likely due to contamination), and was 0.01 ppm on day 14. PCNB was not detected below 6-12 inches. In turf, PCNB was 3350 ppm on day 0, 1297 ppm on day 1, 170 ppm on day 14, 97 ppm on day 30, 13 ppm on day 59, and 2.3 ppm on day 90. PCNB was below th e LOQ at 120, 149, 180, and 209 days. In soil, the degradates PCB, PCA, and PCTA increased in the 0-6" layer and then began to dissipate towards the end of the study. PCB was a maximum of 0.08 ppm on day 149; PCA was a maximum of 0.45 ppm on day 149; and PCTA was a maximum of 0.47 ppm on day 90. The manufacturing contaminant HCB was <LOQ throughout the study. No degradates were detected below the 0-6" layer. In turf, the degradate PCB ranged from 0.13 to 0.20 ppm on days 14-90. It was not detected after the 90 day sampling. PCTA was 1.2 ppm on day 1, 6.3- 6.6 ppm on days 14-59, 0.13-1.8 ppm on days 90-149, 0.60 ppm on day 180, and 0.41 ppm on day 209. HCB and PCA were not detected in turf. The analytical method utilized did not allow for the detection of the potential degradate PCP. This study is classified as acceptable. However, the DT 50 values (observed) indicated that the calculated half-lives overestimated th e rate of dissipation in soil, while underestimating it in turf. It is likely that the problems stem from questionable day 0 data for the soil and from insufficient sampling intervals for the turf.
In the sixth field study, PCNB dissipated with a half-life of 39 days from the upper 6 inches of a Bermuda grass turf plot of sandy loam soil in Califor nia following the second of two applications (33-day interval) of PCNB (Terraclor, 75% WP) at 32.7 lb ai/A/application (MRID’s 41210501, 42094403, 42094404). In the 0- to 6-inch soil depth after the second application, PCNB decreased from 8.60 ppm immediately posttreatment to 3.433 ppm at 63 days, 1.40 ppm at 122 days, and 0.0127 ppm at 332 days. Maximum concentrations of PCNB degradates in the 0- to 6-inch soil depth were 0.430 ppm for PCA at 242 days after the second treatment, 0.117 ppm for PCTA at 242 days after the second treatment, 0.031 ppm for PCB at 151 days after the second treatment. The manufacturing contaminant HCB was a maximum of 0.076 ppm immediately following the second treatment. PCNB was only detected in the 6- to 12-inch soil depth at 0.028 and 0.011 ppm at 0 and 1 day after the first treatment, respectively, and at 0.007 ppm immediately after the second treatment; sporadic detections at lower depths were presumed to be due to contamination rather than leaching. In general, PCNB degradates were <0.01 ppm in the 6- to 12-, 12- to 18-, and 18- to 24-inch depths. The analytical method utilized did not allow for the detection of the potential degradate PCP. This study is classified as acceptable and pr ovides useful data for the risk assessment.
In the seventh field study, PCNB dissipated with a half-life of 128 days from the upper 6 inches of a field plot of loamy sand soil in California treated at 30 lb a.i./A with Terraclor (75% WP) and planted with broccoli following treatment and incorporation of the pesticide (MRID’s 41216401, 42485901). In the 0- to 6-inch soil depth, the average PCNB concentra tion was 4.3 ppm immediately posttreatment, increased to 6.9 ppm at 1 day posttreatment, was 2.7 ppm at 28 da ys, ranged from 1.9 to 3.8 ppm from 56 to126 days, and was 0.30 ppm at 543 days. The degradate PCB reached a maximum concentration of 0.20 ppm at 56 days. The degradate PCTA was a maximum of 0.40 ppm at 28 days. The degradate PCA was a maximum of 0.94

### 112 ppm at 455 days. The manufacturing contaminant HCB was a maximum of 0.056 ppm at 543 days. PCNB was detected sporadically at depths below 6 inches, but the data did not provide evidence of leaching and the detections were likely due to contamination during sampling. The degradates PCA and PCTA did not leach below the 0- to 6-inch layer, while the degradate PCB was detected in the 6- to 12-inch layer where it was a maximum of 0.015 ppm by 543 days posttreatment. The analytical method utilized did not allow for the detection of the potential degradate PCP. This study is classified as acceptable and provides useful data for the risk assessment.
In the eighth field study, PCNB dissipated with a half-life of 193 days from the upper 6 inches of a field plot of sandy loam soil in Minnesota treated at 25 lb ai/A with Terraclor (2 lb/gal EC) and planted with potatoes following treatment and incorporation of the pesticide (MRID’s 41216402, 42485902). In the 0- to 6-inch soil depth, the average PCNB concentration was 4.1 ppm immediately posttreatment, was 3.2 ppm at 7 days, increased to 5.8 ppm at 14 days, decreased to 2.0 ppm by 298 days, and was 0.67 ppm at 546 days. In the 0- to 6-inch soil depth, the degradates PCA and PCB gradually reached maximum concentrations of 1.1 and 0.18 ppm, respectively, by 546 days posttreatme nt. PCTA was a maximum of 0.12 ppm at 56 days; and the manufacturing contaminant HCB was a maximum of 0.025 ppm at 56-84 days. At lower soil depths, PCNB was detected in the 6- to 12-inch soil layer at 0.010-0.011 ppm at 1-14 days posttreatment and at 0.0077 ppm at 126 days; PCNB was not detected (<0.005 ppm ) at other sampling intervals. In the 12- to 18- inch soil layer, PCNB was 0.0067 ppm immediately posttreatment, 0.032 ppm at 28 days, and 0.009 ppm at 56 days; and in the 18- to 24-inch soil layer, PC NB was at 0.0076-0.021 ppm at 7-84 days and 0.0067 ppm at 298 days. The degradate PCB was detected at 0.0072-0.011 ppm at 1 and 14 days posttreatment in the 6- to 12- and 12- to 18-inch soil depths, and at 0.010 ppm at 14 days in the 18- to 24-inch depth (likely due to contamination during sampling). PCA was detected at 0.0071 ppm at 126 days in the 6- to 12-inch depth, was not detected (<0.005 ppm) in the 12- to 18-inch depth, and was detected at 0.011 ppm at 298 days in the 18- to 24-inch depth. PCTA and HCB were not detectedat any depth below 6 inches. The analytical method utilized did not allow for the detection of the potentia l degradate PCP. This study is classified as acceptable and provides useful data for the risk assessment.

### 113 Table B2. Terrestrial field dissipation studies results.

MRID Soil Texture (pH, organic

matter content) Target Applic.

Rate (lb ai/A) Site Plot Type Dissipation Half-life (or

DT 50 ) in

Soil (days) Parent Max. Leaching

Depth Major Degradates & Max. Leaching Depth Applic. Type/ Formulation

43887401 loamy sand (7.2; 0.4%) 212 CA bareground t 1/2 = 272 (r 2 = 0.20) 1 6-12" PCA (6-12") 2 PCTA (0-6") PCB (6-12") broadcast with incorp./granular

43887402 sandy loam (6.5; 1.0%) 232 GA bareground t 1/2 = 459 (r 2 = 0.14) 1 6-12" 3 PCA (6-12") PCTA (0-6") 4 PCB (0-6") 4 broadcast with incorp./granular

43061501 loamy sand (6.4; 0.9%) 10 GA bareground t 1/2 = 57 6-12" PCA (0-6") PCTA (0-6") PCB (0-6") PCP (0-6") PCTASO (0-6") TCTASOO (0-6") broadcast/ granular

41721401 loam (7.7; 3.3%) 25 MN potatoes t 1/2 = 324 6-12" 4 PCA (6-12") PCTA (0-6") pre-emergent broadcast with

incorp./EC
43887403 sandy loam (8.4; 1.2%) 36 CA turf DT 50 = between 30

and 60 6-12" PCA (0-6") PCTA (0-6") PCB (0-6") post-emergent broadcast/WP

41210501 42094403 42094404 sandy loam (6.1; 0.66%) 32.75 CA turf t 1/2 = 39 0-6" 3 PCA (0-6") PCTA (0-6") PCB (0-6") post-emergent broadcast/WP

41216401 42485901 loamy sand (5.6; 0.4%) 30 CA broccoli t 1/2 = 128 6-12" 3 PCA (0-6") PCTA (0-6") PCB (6-12") pre-emergent broadcast with

incorp./WP

41216402 42485902 sandy loam (8.1; 4.3%) 25 MN potatoes t 1/2 = 193 0-6" 3 PCA (0-6") 2 PCTA (0-6") PCB (0-6") 2 pre-emergent broadcast with

incorp./EC

1 Half-life is of questionable valid ity due to high data variability. 2 PCA = pentachloroaniline; PCTA = pentachlorothioanisole; PCB = pentachlorobenzene; PCP = pentachlorophenol; PCTASO = pentachlorothioanisole sulfoxide; TCTASOO = tetrachlorothioanisole sulfon e. 3 Although PCNB was found at one or more lower depths, the detections were considered to be due to contamination during sampling (or other ) rather than to true leaching. 4 The compounds, where noted, were detected at th e next depth at a single sampling interval.

### 114 Bioaccumulation

Bioaccumulation in Fish
PCNB has a very high potential to bioaccumulate in fish tissues, but depurates rapidly from the tissues when the fish are no longer exposed to the compound. Bioaccumulation of PCNB was examined in two guideline studies; additional studies were done to provide metabolite identification information for each of those studies.
In the first study, uncharacterized PCNB resi dues accumulated in bluegill sunfish exposed to [ 14 C]PCNB, at a mean aqueous concentration of 0. 54 ppb (range of 0.31-0.67 ppb), for 28 days. Maximum mean bioconcentration factors (BCF) were 370X for edible tissues, 1800X for viscera, and 960X for whole fish tissues (MRID 40580202). Maximum mean concentrations of total [ 14 C]residues were 200 ppb at 21 days for edible tissue, 990 ppb at 28 days for viscera, and 520 ppb at 21-28 days for whole fish tissues. At the end of the 21-day depuration period, 81-84% of the accumulated [ 14 C]residues were eliminated from the fish tissues. Residues in fish tissue were not characterized in the initial st udy. Thus, an a dditional study was conducted to identify residues that accumulated in the tissues. In the ancillary study, [ 14 C]PCNB residues accumulated in bluegill sunfish that were continuously exposed to the pesticide at a nominal concentration of 0.70 μg/L for 28 days under flow-through conditions. After 21 and 28 days of exposure, the concentration of [ 14 C]residues in the edible and nonedible fish tissues totaled 170-200 and 1100-1200 μg/kg, respectively (MRID 43179301). Three [ 14 C]compounds isolated from the fish tissues were identified as N-acetyl Spentachlorophenyl cystine (the cystinyl conjugate of PCNB), PCTA and PCTASO. One additional [ 14 C]compound, Metabolite 8, was isolated from the fish ti ssues but was not identified. In the edible tissue of fish after 21 or 28 days of exposure, PCTA was 161.22-232.33 ppb and the cystinyl conjugate of PCNB was 0.76-1.22 ppb. In the 21-day sample only, Metabolite 6 was isolated at 0.85 ppb. In the nonedible tissue of fish after 21 days of exposure, PCTA was 1094. 61 ppb, the cystinyl conjugate of PCNB was 30.97 ppb, and Metabolite 6 was 8.47 ppb. In the nonedible tissue of fish after 28 days of exposure, PCTA was 696.41 ppb, the cystinyl conjugate of PCNB was 24.89 ppb, PCNB was 9.50 ppb, and Metabolite 8 was 0.98 ppb. Unextracted [ 14 C]residues totaled 14-19.4% of applied in the ed ible tissues and 11.6-31.5% of applied in the nonedible tissues. While the initial bioaccumulation study is classified as supplemental when considered on its own, the ancillary study is acceptable, and togeth er the two studies provide adequate data for the risk assessment.
In the second bioaccumulation in fish study, unchar acterized PCNB residues accumulated in bluegill sunfish exposed to [ 14 C]PCNB, at 1.0 ppb, for 35 days. Maximum mean bioconcentration factors (BCF) were 400X for edible tissues, 1800X for viscera, and 1100X for whole fish tissues (MRID 41200001). Although, in retrospect, the BCF’s are comparable to those dete rmined in the first study, this study was considered invalid upon review due to problems achieving a consta nt aqueous exposure concentration. Maximum mean concentrations of total [ 14 C]residues, at 35 days, were 350 ppb for edible tissue, 1600 ppb for viscera, and 930 ppb for whole fish tissues. At the end of th e 21-day depuration period, 78% of the accumulated [ 14 C]residues were eliminated from the edible and viscera tissues. Residues in fish tissue were not characterized in the initial study. Thus, an add itional study was conducted to identify residues that accumulated in the tissues. For both edible and vi scera tissues, the predominant compound detected in the organic extract of the tissues was the degradate PC TA (MRID 41951701). These studies (taken together) are classified as supplemental and provide some useful information for the risk assessment.

### 115 NO 2

Cl

Cl

Cl Cl Cl

NH 2

Cl

Cl

Cl Cl Cl

SCH 3

Cl

Cl

Cl Cl Cl

Cl

Cl

Cl Cl Cl APPENDIX C. STRUCTURES FOR PCNB AND ITS MAIN FATE DEGRADATES

Chemical Name and Structure

Parent: PCNB (pentachloronitrobenzene) CAS 82-68-8

Degradate 1: pentachloroaniline (PCA) CAS 527-20-8

Degradate 2: pentachlorothioanisole (PCTA) CAS 1825-19-0

Degradate 3: pentachlorobenzene (PCB; also present as an impurity) CAS 608-93-5Chemical Name and Structure



### 116 SCH 3

Cl

Cl Cl Cl

Cl O

SCH 3

Cl

Cl Cl Cl

Cl O O

OH

Cl

Cl Cl Cl

Cl Degradate 4: pentachlorothioanisole sulfoxide

Degradate 5: pentachlorothioanisole sulfone

Degradate 6: PCP (pentachlorophenol) CAS 87-86-5Chemical Name and Structure



### 117 Cl

Cl

Cl

Cl Cl Cl Manufacturing Contaminant: hexachlorobenzene (HCB)

### 118 APPENDIX D1. DRINKING WATER ASSESSMENT (TIER I)

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDES, AND TOXIC SUBSTANCES

PC Code: 056502 DP BARCODE: 291286

MEMORANDUM November 12, 2003

SUBJECT: Pentachloronitrobenzene: Tier I Drinking Water EDWCs for Use in the Human Health Risk Assessment.
TO: Mohsen Sahafeyan, Chemist RRB2/HED (7509C)
FROM: Cheryl A. Sutton, Ph.D. Environmental Scientist ERBIV/EFED (7507C)
THRU: R. David Jones, Ph.D., Senior Agronomist ERBIV/EFED (7507C)
Elizabeth Behl, Branch Chief ERBIV/EFED (7507C)
This memo summarizes the Tier I estimated drinking water concentrations (EDWC) for pentachloronitrobenzene [PCNB; plus the degradate pent achloroaniline (PCA), as described below] in surface water and in groundwater for use in the human health risk assessment. The EDWC’s are summarized in Table 1. Because the surface water EDWC values (as estimated by FIRST) are controlled by the solubility of PCNB (440 μg L -1 ) rather than by the degradation rate, there is no difference the in EDWC whether PCA is included in the estimate or not. This may not hold if mo re refined assessments with PRZM and EXAMS are done. EFED used the screening model FIRST (FQPA Index R eservoir Screening Tool) to calculate the surface water EDWC’s and used the screening model SCI-G ROW (Screening Concentrations in Ground Water) to calculate the groundwater EDWC. Because PCNB is a re gistered chemical alread y in use, a search for monitoring data was conducted; the results are discu ssed in a separate section below. Because monitoring data for PCNB are scarce and of limited value in term s of this assessment, they are presented only for their qualitative value; they were not used quantitatively in the drinking water assessment.
In response to a decision made by the MARC committee (27 May 2003; Final Decision), the EFED scientist was to conduct the drinking water assessment to account for the parent compound plus two PCNB degradates considered to be residues of concern, pentachloroaniline (PCA) a nd pentachlorophenol (PCP). Because PCP is a known carcinogen, it will be consider ed separately in this assessment. Because PCP was not monitored and/or detected in most of the s ubmitted guideline studies, the evaluation of the compound in

### 119 terms of its presence in drinking water as a result of PCNB use will be qualitative. To account for the degradate PCA, aerobic soil metabolism half-lives de termined for the parent compound in the guideline studies were recalculated using concentration data for the parent compound plus PCA. Because separate aqueous photolysis data were not available for PCA, and the compound was not detected in the irradiated solutions initially containing the parent compound, th e photolysis half-life used in the modeling was calculated using parent compound concen tration data only. The lack of information on the photolysis rate of PCA comprises a small uncertainty surrounding the su rface water EDWCs. For the input parameter values for soil adsorption (K oc in SCI-GROW and K d in FIRST), the reviewer usedthe soil adsorption coefficients determined only for the parent compound. Based on s ubmitted data, however, the mobility of PCA is similar to that of the parent compound, in that both compounds are generally expected to adsorb to soil and organic matter and have a low leaching potential.
In general, PCNB is a persistent , volatile compound that will be immobile in most soils, but may have slight or even moderate mobility in coarser (sandy) so ils, particularly those that are low in organic matter. While PCNB is expected to be persistent in aerobic environments, it is microbially degraded more rapidly (DT 50 's of <30 days) in anaerobic environments. It is stable to hydrolysis and is effectively stable to photodegradation on soil, but appears (based on two submitted studies) to photodegrade fairly rapidly in water, with half-lives on the order of a few days or less. (While evidence of aqueous photodegradation of PCNB was not found in the literature, EFED found the s ubmitted studies acceptable and, therefore, used the half-life values determined in those studies.) In fiel d studies, the compound has been shown to dissipate more rapidly in the plots in which the pesticide was not in corporated, with a half-life range of 39-57 days versus a half-life range of 128-324 days for plots with incor porated PCNB. The major degradates of PCNB in the environment are PCA and pentachlorothioanisole (P CTA); minor degradates are pentachlorothioanisole sulfoxide (PCTASO), pentachlorothioanisole sulfone (PCTASO 2 ), and pentachlorobenzene (PCB), which is also present as an impurity along with hexachlorobenzen e (HCB). While PCP was detected in two of the submitted studies, there is not sufficient evidence (eith er from the submitted data or from published literature, as discussed later in this memo) that the compound will routinely be formed from PCNB in the environment.

Table 1. Tier I EDWCs for dr inking water risk assessment.

Surface water drinking water sources acute: 440 μg/L (ppb) 1 chronic: 440 μg/L (ppb)
Groundwater drinking water sources 30.6 μg/L (ppb) 2

1 Surface water EDWC’s (acute and chronic) are based on PCNB use on turf at 32.67 lb a.i./A/applica tion in two applications (tota l application rate of 65.34 lb a.i./A. Note that 440 ppb is the aqueous solubility limit of PCNB at 25 o C. 2 Groundwater EDWC’s are based on PCNB use on bulb crops at 213.4 lb a.i./A/application in a single application.
Estimated Drinking Water Concentrations
For the surface water and groundwater assessments, the application rates for turf (2 applications of 32.67 lb a.i./A/application), peanuts (2 applications of 10 lb a.i./A/application), cole crops (1 application of 30 lb a.i./A), potatoes (1 application of 25 lb a.i./A ) and bulb crops (1 application of 213.4 lb a.i./A) were initially used, which represent the hi ghest annual application rates on the labels (as presented in the Use Closure Memo for PCNB Reregistration of 1/23/03, ame nded 6/23/03) for soil or foliar applications of PCNB. Seed treatment usage rates were considered (after conve rsion to field application rates by multiplying by the typical seeding rates for each crop; rates were obtained from Appendix V of EFED’s 9/12/03 Ecological Risk Assessment for the Carboxin Reregistration Eligibility Deci sion), but did not result in field application levels greater than those for soil and foliar applications. Th e soil drench application scenario (applicable to many crops) was modeled to determine preliminary EDWC’s for such uses. While these values are reported here

### 120 (in a separate table), they are to be considered prelim inary values and should not be used in the human health risk assessment at this time. Prior to a final determin ation of EDWC’s associated with a soil drench use, it is necessary that EFED obtain additional information fro m the registrants regarding this use pattern. A summary of the model input parameter values used in FI RST to model soil and foliar applications is presented in Table 2. The FIRST output file is located in A ttachment 1. A summary of the model input parameter values used in SCI-GROW to model soil and foliar app lications is presented in Table 3. The SCI-GROW output file is located in Attachment 2. A table of the source data used to determine input parameter values is located in Attachment 3.
FIRST (v1.0) is a screening-level model designed to estimate the pesticide concentrations found in surface water for use in drinking water assessm ents. The model provides upper bound estimates of environmental concentrations (acute and chronic) in surface water drinking water sources (untreated) that might occur following the use of a pesticide. FIRST u ses basic environmental fate data and pesticide label use and application information to estimate the EEC s following the treatment of a 10-hectare field with subsequent runoff into a reservoir (an Index Reservoir, based on Shipman City Lake in Illinois, a 13-acre lake 9-feet deep with a watershed area of 427 acres or 172. 8 hectares) that undergoes two full turnovers annually. FIRST also uses a Percent Cropped Area (PCA) factor to adjust for the area within the watershed that is planted to the modeled crop. In the model, a single runoff event occurs two days after the last application and can move a maximum of 8% of the applied pestic ide into the reservoir, with the amount dependent on the degradation and adsorption of the pesticide which occu rs in the field prior to th e event, any incorporation of the pesticide at the time of application, and the PCA. The model also accounts for degradation and binding to sediment which may occur in the reservoir following the runoff event. Spray drift (resulting in direct deposition of the pesticide into th e reservoir or indirect loading from spray drift landing on the feeding stream) in the model is equivalent to 16% of the applied for aerial application, 6.3% for orchard air blast application, and 6.4% for other ground spray application.
SCI-GROW2 is a regression-based, Tier 1 screeni ng model that provides a groundwater exposure value to be used in determining the potential risk to human health from drinking water contaminated with the pesticide. SCI-GROW2 estimates likely groundwater concen trations if the pesticide is used at the maximum allowable rate in areas where groundwater is vulnerable to contamination. Characteristics of such vulnerable areas include high rainfall, rapidly permeable soil, and a shallow aquifer. In most cases, a large majority of the use area will have groundwater that is less vulnerable to contamination than the areas used to derive the SCI-GROW2 estimate.

EFED recommends that the acute EDWC to be usedin the human health risk assessment for surface water is 440 ppb, based on the use of PCNB on turf at an application rate of 32.67 lb a.i./A/application for two applications with an application in terval of 21 days (total application rate of 65.3 lb a.i./A). It is noted that for all of the aforementioned crops modeled with soil/foliar applications (with total maximum application rates ranging from 20 to 213.4 lb a.i./A), the same acute EDWC’s (i.e., 440 ppb) were obtained. Note, also, that the value “440 ppb” is the aqueous so lubility limit of the parent compound at 25 o C. EFED recommends that the chronic EDWC to be used in the drinki ng water assessment for surface water is 440 ppb, also based on the use of PCNB on turf, as described previously. Wh ile the use of PCNB on bulb crops at an application rate of 213.4 lb a.i./A/application with a single appli cation and no incorporation resulted in the same chronic EDWC for surface water of 440 ppb, the same use (i.e., bulbs) only with incorporation to 6 inches resulted in a lower chronic EDWC of 328.6 ppb. For the pur poses of comparison, EFED determined the acute and chronic surface water EDWC’s for parent PCNB only (without including PCA), using the turf application scenario. The EDWC’s for parent only were 440 ppb fo r both acute and chronic exposures, indicating that

### 121 the inclusion of PCA did not have an apparent e ffect on the surface water EDWC’s, as they were more significantly affected by the aqueous solubility limit of the compound.

EFED recommends that the EDWC to be used in the human health risk assessment for groundwater is 30.6 ppb, based on the use of PCNB on bulb crops at an application rate of 213.4 lb a.i./A, applied in a single application. For the purposes of comparison, EFED determined the groundwater EDWC for parent PCNB only (without including PCA), using the bulb app lication scenario. The EDWC for parent only was 13.0 ppb, indicating that the inclusion of PCA did have an effect on the groundwater EDWC.

### 122 Table 2. FIRST (v1.0) input parameter values a nd results for PCNB applied to various crops.

Parameter Value
Application Rate (lb a.i./A) turf: 32.67 potatoes: 25 peanuts: 10 bulb crops: 213.4 cole crops: 30
Number of Applications turf: 2 potatoes: 1 peanuts: 2 bulb crops: 1 cole crops: 1
Interval between Applications (days) turf: 21 potatoes: NA peanuts: 30 bulb crops: NA cole crops: Not Applicable (NA)
Soil Partition Coefficient (K d ; mL/g) 15.5 (MRID 41648201; lowest non-sand K d )
Aerobic Soil Metabolism Half-life (days) t 1/2 = 1555 days (parent plus PCA) (source data from MRID’s 42911902, 41384501, 41713202, 42112801) 1

Wetted in? No
Depth of Incorporation (inches) turf: 0 potatoes: 0 peanuts: 0 bulb crops: 0; 6 cole crops: 0
Method of Application turf: ground application of granular peanuts: ground application of granular

cole crops: ground spray (broadcast) potatoes: ground spray (broadcast) bulb crops: ground spray (broadcast); granular
Percent Cropped Area 0.87 (all crops modeled here)
Solubility in Water (mg/L or ppm) 0.44
Aerobic Aquatic Metabolism Half-life (days) t 1/2 = 3110 days (parent plus PCA) 1 (source data from MRID’s 42911902, 41384501, 41713202, 42112801) (input value is two times the aerobic metabolism half-life input value)
Hydrolysis Half-life @ pH 7 (days) stable
Aquatic Photolysis Half-life @ pH5 (days) 1.83
FIRST Results (Estimated Drinki ng Water Concentrations for surface water) Acute Concentration (ppb): 440 2 (all crops) Chronic Concentration (ppb): turf: 440.0 peanuts: 183.6 cole crops: 301.4 potatoes: 251.2 bulb crops: 440.0; 328.6 3

1 For the purposes of the drinking water assessm ent, half-lives were recalculated to acc ount for the parent plus the degradate PC A. The aerobic soil metabolism half-life used in the models represents the 90 thpercentile of the upper confidence bound on the mean half-life for two soils. The aerobic aquatic metabolism half-life was determined , in the absence of study data, by multip lying the aerobic soil metabolism half-life model input value by two to account for the uncertainty associated with a lack of true aquatic metabolism study data. 2 Note that 440 ppb, the acute concentration for all scenarios modeled, is the aqueous solubility limit for PCNB at 25 o C. 3 Because FIRST does not allow directly for incorporati on of a non-granular formulation (as is done for this usage), the EDWC was also determined for this crop (2 nd value reported) using a granular formulation incorporated to 6 inches to represent the use of either a granular OR a non-gr anular formulation (F, WP or WSP) incorporated to 6 inches. Th e first value reported corresponds to a use scenario with no incorporation.

### 123 Table 3. SCI-GROW2 input parameter values and results for PCNB applied to various crops by soil or foliar applications only.

Parameter Value
Maximum Application Rate (lb a.i./A/application) turf: 32.67 peanuts: 10 cole crops: 30 potatoes: 25 bulb crops: 213.4
Maximum Number of Applications per Year turf: 2 (21-day interval) peanuts: 2 (30-day interval) cole crops: 1 potatoes: 1 bulb crops: 1
Aerobic Soil Metabolism Half-life (days) t 1/2 = 750.5 days (parent plus PCA; average of two values) 1
Organic Carbon Partition Coefficient (K oc ) 1588 (lowest value of four; based on parent compo und only) (MRID 41648201)

Results (Estimated Drinking Water Concentrations for groundwater, in ppb) turf: 9.38 peanuts: 2.87 cole crops: 4.31 potatoes: 3.59 bulb crops: 30.6

1 For the purposes of the drinking water assessm ent, half-lives were recalculated to acc ount for the parent plus the degradate PC A, as requested by the MARC.
Preliminary EDWC’s for a Soil Drench Use Scenario

To allow for a determination of EDWC’s for all of the potential label uses of PCNB, the soil drench application scenario (applicable to many crops) was modeled to determine preliminary EDWC’s for such uses. Although the application scenario is reported as a so il drench use on beans (dry type), a soil drench use on multiple other crops with the same application rate (i.e., 40.84 lb a.i./A/application) will yield the same values. The values are reported in Table 4 are to be c onsidered preliminary values and should not be used in the human health risk assessment at this time. Prior to a final determination of EDWC’s associated with a soil drench use, it is necessary that EFED obtain additional information from the registrants on this use pattern, particularly with regard to drenching pr actices, time between drench and transplant, number of treatments, estimated amount of pesticide/formulated product not retained in the drenched container, and planting densities for transplants in the field. Please note that the preliminary values were determined with a usage scenario which included a single application of the pesticide. Although the label appears to allow for two applications (with a 28-day interval) per grow ing season at this rate, it is unclear as to when the applications would occur relative to the transplant to the field. Thus, at this time, EFED utilized a single application in the use scenario.

### 124 Table 4. Tentative Tier I EDWCs for drinking water based on a soil drench use scenario.

Surface water drinking water sources acute: 207.3 μg/L (ppb) 1 chronic: 62.9 μg/L (ppb)
Groundwater drinking water sources 5.9 μg/L (ppb)

1 Surface water and groundwater EDWC’s are base d on PCNB use on beans (dry-type) at 40.84 lb a.i./A/application in a single appli cation . Note that this application rate is the same as that used for multiple othe r crops with a soil drench applica tion usage. Note also that 4 40 ppb is the aqueous solubility limit of PCNB at 25 o C.
Monitoring Data
NAWQA monitoring data are not available. Based on information contained in the USEPA’s Pesticides in Ground Water Database, A Compilation of Monitoring Studies: 1971-1991, National Summary , PCNB is not found in groundwater at significant levels or frequencies. In sampling of 1708 wells, only three detections of PCNB occurred, at a range of 0. 008–0.275 μg/L. Sampled wells which did not contain measurable levels of PCNB included 459 wells in California, 71 in Maine, 649 in Minnesota, 263 in Mississippi, 10 in Oregon and 188 in Texas. However, th ere is no related information available with regard to whether the monitoring sites corresponded with PCNB use sites or times of usage. Updated monitoring data from STORET are not available; it is no longer possible to query either the historical database (in the Legacy Data Center) or the new database (ModernizedSTORET) to obtain all detections of a specific compound.
To supplement the monitoring data available to EFED in-house, a literature search was conducted to obtain published information (generally post-1990 onl y) on the occurrences of PCNB and its degradates in the aquatic and terrestrial environments; informa tion on the former are included below. PCNB and its major degradates PCA and PCTA have not been detectedfrequently in North America. The presence of PCA and PCTA in the environment are most likely a result of the use of PCNB. Detections of the potential degradate PCP in the environment cannot necessarily be a ttributed to its existence as a degradate of PCNB, but are most likely a result of its use as a pesticide (w ood preservative). Similarly, detections of the degradate (and impurity in PCNB) PCB in the environment are mo st likely a result of its existence as a byproduct in the manufacture of other compounds or as a degradate of hexachlorobenzene (HCB), and its industrial uses.

In a groundwater monitoring study of 18 wells in three counties in California (July 1994–1995), PCNB was not detected (California EPA, 1995). In a review of multiple studies in which sampling was conducted in surface water and/or groundwater at golf courses, PCNB was monitored in surface water in an unspecified number of studies, but was not detected (Cohen et al., 1999).
The degradates PCA, PCB and PCP were monito red in the Mississippi River and many of its tributaries (Illinois, Missouri, Ohio, Arkansas, White , and Yazoo Rivers; Rostad et al., 1993). PCA was detected in the surface waters at multiple locations, at concentrations of 0.018-0.055 ng/L. PCB was detected in the Mississippi River and two of its main tributaries, but was not likely a result of PCNB use. Its presence was attributed to its existence as a degradate of HCB, as suggested by the concentration profiles of the two compounds. PCP was not found in any of the surface water samples.
In summary, monitoring data on PCNB are somewhat scarce and/or incomplete information is available. As such, the data may be taken at f ace value, but are not substantial enough to quantitatively incorporate into the drinking water assessment. Additiona lly, the data have limitations in that it is not clear

### 125 in most cases whether the water bodies/wells monitored co rrespond with or were even targeted to correspond with PCNB usage in terms of location and/or time.
Pentachlorophenol
It was decided by the MARC committee that both pentachloroaniline (PCA) and pentachlorophenol (PCP) were both PCNB degradates of concern in wate r. Thus, the drinking water assessment must take into account these degradates in addition to the parent co mpound. The degradate PCA was accounted for by the recalculation of the parent half-lives, as described previ ously in this memo. As aforementioned, the degradate PCP, a known carcinogen, must be considered independe ntly of PCNB and PCA. In the submitted guideline studies, pentachlorophenol (PCP) was detected as a degradate of PCNB in only two of the studies, an anaerobic soil metabolism study and a terrestrial field dissipation study. In the anaerobic soil metabolism study, PCP was first detected in the soil, at 0.28 ppm, immediately after the induction of anaerobic conditions at 30 days, and was 0.33 ppm at 90 days (60 days post-flooding); in the water phase, PCP was 0.048 ppm at 60 days and 0.037 ppm at 90 days. [It is noted that, given current EFED modeling requirements, data from aerobic and anaerobic aquatic metabolism studies are gene rally considered more useful than data from the anaerobic soil metabolism studies.] In the terrestrial field dissipation study in which PCP was detected, the compound was detected immediately after application at 0.022 ppm, increased with time to a maximum of 0.161 ppm by day 16, then decreased to 0.008 ppm by day 60, and was below the limit of quantification (LOQ; 0.005 ppm) by 120 days. The lack of detection of PCP in the second submitted anaerobic soil metabolism study and the other seven field dissipation studies does not indicate that the compound wasn’t present; it was simply not monitored in those studies. In a single aerobic soil metabolism study in which PCP was monitored, the compound was not detected.
As submitted data on PCP (specifically, as a degradate of PCNB) are lacking, the treatment of PCP in EFED’s Tier I assessment must be qualitative in na ture. The conclusions presented here were drawn mainly from information obtained from the published literature, as cited where appropriate. Essentially, evidence that PCP is formed from PCNB during microbial degradation in soil has been found in the literature, but the weight of evidence is not substantial. EFED has indicated to SRRD that additional data on the microbial metabolism of PCNB in both aerobic and anaerobic soil/water systems are necessary for a more complete evaluation of the risks (particularly with regard to PCP) associated with the use of PCNB.
PCP has been reported to be a “major” degrad ate of PCNB when the compound is microbially metabolized in soil (Murthy & Kaufman, 1978; Motoyama et al., 2001). However, the term “major” was not defined in either of the publications and the second pub lication merely cited the first as the source of their information, as did other studies found in the literatur e. Thus, EFED’s fairly extensive literature search resulted in only one primary reference in which it was st ated that PCP is a soil metabolite of PCNB. Attempts to contact the study authors or their successors at the (former) USDA Pesticide Degradation Laboratory were unsuccessful.
In the first publication (i.e., Murthy & Kaufman), the study authors were unable to quantify the amount of PCP formed, as they discarded the aqueous portion (which accounted for 8-16% of the 56-58% of the applied that was extracted from the soil samples, for a maximum possible level of 9.28% of the applied) of their extract following an organic extraction, and were therefore unable to analyze the aqueous phase for PCP. In subsequent investigati ons, the study authors were able to determine (through GLC and TLC) that PCP was the compound present in the aqueous phase of th e soil extract, but did not attempt to quantify the residues.

### 126 In a study done in Japan, it appears that PCP was not detected in a volcanic ash soil which had been extensively treated in the past with PCNB and in wh ich the parent compound was detected in the soil at 10.10 ppm (Ohsawa et al., 1984). However, the compound pentachloroanisole (PCA), which is a methylated derivative of and can interconvert with PCP under certa in conditions, was detected at 0.009 ppm. (Further interpretation of this study was hindered by the fact th at much of the text was in Japanese and a translation was not available.) It has been suggested in the literature that PCA is the product of the microbial degradation of PCP following that compound’s form ation from PCNB by soil microbes (Murthy andKaufman, 1978; Murthy et al., 1979). In a study of PCNB degradation by fungi, PCA was detected (MoraTorres et al., 1996). In a study on PCNB degradation by soil microbes native to France, neither PCP nor PCA were observed; degradates included only PCA and PCTA (Mora-Torres et al ., 2000).
In a study of the metabolism of PCNB in anaer obic sediment in Japan, PCP was not identified as a degradate; degradates included pentachloroaniline, 2, 3,4,5-tetrachloroaniline, 3,4,5-trichloroaniline, 3,5- dichloroaniline and 3-chloroaniline (with 2-CA and 4-CA identified as intermediates; Susarla et al., 1996). Tetrachloroaniline has also been identified as a metabolite of PCNB in other studies (Mora-Torres et al., 1996).

These results indicate that there are conditions unde r which PCP can form in the environment, but does not form under all conditions. At this point in tim e, we do not have sufficient information to determine what conditions favor PCP formation and which do not. Nor is there sufficient information to quantify the amount and rate of formation of PCP from PCNB wh en PCP is produced. Consequently, EFED is unable to estimate how much PCP might occur in drinking wate r from PCNB use. EFED has indicated to SRRD that additional data on the microbial metabolism of PCNB in both aerobic and anaerobic soil/water systems are necessary for a more complete evaluation of the risks associ ated with PCNB, particularly with regard to PCP.

Literature Cited
California EPA; Sampling for pesticide residues in California well water. 1995 Update of The Well Inventory Database in California. CA Environmental Protection Agency, Dept. of Pesticide Regulation, 10 thAnnual Report. (December 1995)
Cohen, S., A. Svrjcek, T. Durborrow, N. Lajan Barnes. Water quality impacts by golf courses. J. Environ.Qual. 28:798-809.
Mora-Torres, R., C. Grosset and J. Alary. Chromatographia 51:526-530 (2000).
Mora-Torres, R., C. Grosset, R. Steiman, and J. Alary. Liquid chromatography study of degradation and metabolism of pentachloronitrobenzene by four soil micromycetes. Chemosphere 33:683-692 (1996).
Motoyama, T., K. Kadokura, S. Tatsusawa, T. Arie, and I. Yamaguchi. Application of plant microbe systems to bioremediation. RIKEN Re. 42:35-38 (2001).
Murthy, N.B.K. and D.D. Kaufman. Degradation of pentachloronitrobenzene (PCNB) in anaerobic soils. J. Agric. Food Chem. 26:1151-1156. (1978).
Murthy, N.B.K., D.D. Kaufman and G.F. Fries. De gradation of pentachlorophenol (PCP) in aerobic and anaerobic soil. J. Environ. Sci. Health B14:1-14 (1979).

### 127 Ohsawa, K., T. Miyamoto, and I. Yamamoto. Residue analysis of pentachloron itrobenzene and its related compound ( sic ) in soils by mass fragmentography. J. Pestic. Sci. 9:339-345 (1984).
Rostad, C.E., W.E. Pereira and T.J. Leiker. 1999. Distribution and transport of selected anthropogenic lipophilic organic compounds asso ciated with Mississippi River suspended sediment, 1989–1990. Archives of Environ. Contam. and Tox. 36:248–255.
Susarla, S., S. Masunaga and Y. Yonezawa. Transf ormation of chloronitrobenzenes in anaerobic sediment. Chemosphere 32:967-977 (1996).
USEPA. Pesticides in groundwater database. A comp ilation of monitoring studies: 1971-1991. National summary. USEPA/OPP/OPPTS. USEPA-734-12-92-001 (1992).

### 128 Attachment 1: FIRST File

RUN No. 1 FOR pcnb ON turf * INPUT VALUES *

-------------------------------------------------------------------- RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE %CROPPED INCORP ONE(MULT) INTERVAL Kd (PPB ) (%DRIFT) AREA (IN)

-------------------------------------------------------------------- 32.670( 65.036) 2 21 15.5 440.0 GRANUL( .0) 87.0 .0

FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

-------------------------------------------------------------------- METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (RESERVOIR) (RES.-EFF) (RESER.) (RESER.)

-------------------------------------------------------------------- 1555.00 2 N/A 1.83- 226.92 ****** 211.49

UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.0 AUG 1, 2001

-------------------------------------------------------------------- PEAK DAY (ACUTE) ANNUAL AVERAGE (CHRONIC) CONCENTRATION CONCENTRATION

-------------------------------------------------------------------- 440.000 440.000

### 129 Attachment 2: SCI-GROW File

SCIGROW VERSION 2.3 ENVIRONMENTAL FATE AND EFFECTS DIVISION OFFICE OF PESTICIDE PROGRAMS U.S. ENVIRONMENTAL PROTECTION AGENCY SCREENING MODEL FOR AQUATIC PESTICIDE EXPOSURE

SciGrow version 2.3 chemical:pcnb time is 10/20/2003 13:19:59

------------------------------------------------------------------------ Application Number of Total Use Koc Soil Aerobic rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

------------------------------------------------------------------------ 213.400 1.0 213.400 1.59E+03 750.5

------------------------------------------------------------------------ groundwater screening cond (ppb) = 3.06E+01 *************************************************************************

### 130 Attachment 3: General fate and physical-chem ical property source data for PCNB modeling.

PARAMETER VALUE
Chemical Name pentachloronitrobenzene Molecular Weight 295.3 Solubility (25 o C) 0.44 mg/L (440 ppb) Vapor Pressure (25 o C) 1.13 x 10 -4 mmHg Hydrolysis Half-life (pH 5, 7, 9; 25 o C) stable (MRID’s 40865301, 40972601) Aqueous Photolysis Half-life (pH 7) t 1/2 = 2.5 days (MRID’s 42606201, 42606202) t 1/2 = 26.8 hours (MRID 42336201) Soil Photolysis Half-life stable (MRID’s 41004801, 41713201)

Aerobic Soil Metabolism Half-life t 1/2 = 77, 189 days (parent only); t 1/2 = 489, 1012 days (parent plus PCA) 1 t 1/2 = 983, 1052 days (total residues) 2 (MRID’s 42911902, 41384501, 41713202, 42112801)

Anaerobic Soil Me tabolism Half-life t 1/2 = 9 days, <30 (DT 50 ; parent only); t 1/2 = 210, 410 days (parent plus PCA, PCP) t 1/2 = 268, 334 days (total residues) (MRID’s 41203602, 42094401, 41384301, 41686001, 41713202, 42112802) Organic Carbon Partition Coefficient (K oc ) 1588, 2912, 3870, 17508 (MRID 41648201) Soil Partition Coefficient (K d , mL/g) 7.3, 15.5, 19.1, 210 (MRID 41648201)

1 For the purposes of the drinking water assessm ent, half-lives were recalcu lated to account for the pare nt plus the degradates P CA and PCP, when monitored and detected. 2 For the purposes of the ecological assessmen t, half-lives were recalculated to acc ount for total residues, inclusive of the parent plus the degradates PCA, PCTA, PCB, PCP, PCTASO, PCTASO 2 , and the manufacturing contaminant HCB.

### 131 APPENDIX D2. DRINKING WATER ASSESSMENT (TIER II)

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDES, AND TOXIC SUBSTANCES

PC Code: 056502 DP BARCODE: 291286

MEMORANDUM July 15, 2004

SUBJECT: Pentachloronitrobenzene, Second Revised Drinking Water Assessment: New Tier II Drinking Water EDWCs for Use in the Human Health Risk Assessment.
TO: Mohsen Sahafeyan, Chemist RRB2/HED (7509C)
FROM: Cheryl A. Sutton, Ph.D. Environmental Scientist ERBIV/EFED (7507C)
THRU: Kevin Costello, Ri sk Assessment Process Leader ERBIV/EFED (7507C)
Elizabeth Behl, Branch Chief ERBIV/EFED (7507C)
This memo summarizes the most recent Tier II estimated drinking water concentrations (EDWC) for pentachloronitrobenzene [PCNB; plus the degrad ate pentachloroaniline (PCA), as described in the 11/12/03 memo in which Tier I screening level EDWC’s were presented] in surface water for use in the human health risk assessment. The surface-water va lues presented here are revised from those in the previous two memos (11/12/03 and 12/15/03); the reasons for the revisions are described below. The values for groundwater presented in the initial memo have not changed. Available monitoring data and information on PCP have also not changed; deta ils on these issues can be found in the 11/12/03 memo (attached).
This memo presents new Tier II surface water EDWC ’s which were determined using the Tier II screening models PRZM/EXAMS. While the acute value has not changed from the previous DWA, the chronic value and the 30-year average value have both increased. While the previous DWA reported values associated with use on cabbage, th e current values are associated with use on turf. In contrast to earlier modeling conducted with PRZM/EXAMS, the current modeling was done without the inclusion of the PRZM volatilization routine , as EFED was recently made aware by EPA’s Office of Research and Development (ORD) that the routine in the currently used version of PRZM contains some incorrect algorithms and does not accurately estimate volatilization from the soil. While a newer version of PRZM/EXAMS has been developed, in which the volatilization routine has been corrected, EFED has not yet had the opportunity to QA/QC the model. Once that process is completed (estimated to be done by Fall 2004), EFED will then provide HED with upda ted EDWC’s that also reflect volatilization. Taking volatilization into account will likely reduce concentrations from those estimated in this assessment. Until that time, the EDWC’s recommende d by EFED for use in the human health risk assessment for PCNB are those presented inTable 1

.

### 132 Table 1. Estimated Drinking Water Concentrat ions for use in the PCNB human health risk assessment.

Surface water drinking water sources acute: 440 μg/L (ppb) 1 1-in-10-years (chronic): 65.5 μg/L (ppb) 30-year average: 33.7 μg/L (ppb) Groundwater drinking water sources 30.6 ug/L (ppb) 2

1 Surface water EDWC values (Tier II screening level) were genera ted using the PRZM/EXAMS model w ith a foliar/ground spray to tur f in Pennsylvania application scenario (two applications of 33.67 lb a.i./A, at a 21-day interval). The actual output value from P RZM/EXAMS was 587.7 ppb for the turf use acute concentration. However, as this is greater than the aqueous so lubility of 440 ppb for PCNB, t he solubility limit should be used instead. 2 Groundwater EDWC’s (Tier I screening level) are based on PC NB use on bulb crops at 213.4 lb a.i./A/application in a single application. Reported values represent the maximum concentr ation levels resulting from the labeled uses (excluding ornamental, greenhouse or residential uses) . The general fate and physical-chemical property data used as the source of the modeling input para meter values were obtained from the guideline studies and other submissions from the registrant and are presented in Table 2 . Some of the input values have been changed since the DWA conducted in 12/2003, mo st notably the incorporation depths and CAM numbers (which reflect pesticide application practices) used for some of the crops. The incorporation depth values used in this DWA were obtai ned from specific labels, as indicated in Table 2 . Another change affecting the EDWC’s was the correction of model output values to account for the Percent Cropped Area; this was not done in the previous DWA (despite statements which indicated such). While the anaerobic aquatic metabolism half-life input value w as also changed, it did not have any effect on the EDWC’s.

### 133 Table 2. PRZM/EXAMS input parameter values for PCNB plus PCA for the drinking water assessment.

Parameter Value Source and/or Comments

Application Rate (lb a.i. /A/application) turf: 32.67 peanuts: 10 cabbage (cole crop): 30 potatoes: 25

cotton: 2 Reg. 5481-419 (LUIS line 1524) Reg. 5481-472 (LUIS line 1405)

Reg. 400-453 (LUIS line 360) Reg. 5481-450 (LUIS line 1503)

Reg. 400-399 (LUIS line 630)
Number of Applications turf: 2 peanuts: 1 cabbage: 1 potatoes: 1 cotton: 1 Reg. 5481-419 Reg. 5481-472 Reg. 400-453 Reg. 5481-450 Reg. 400-399
Interval Between Appli cations (days) turf: 21 peanuts: Not Applicable (NA) cabbage: NA potatoes: NA cotton: NA Reg. 5481-419

–

–

–

-- Date of First Application turf: November 15 (post-emergent) peanuts: April 15 (pre-plant) cabbage: August 15 (pre-plant) potatoes: May 20 (pre-plant) cotton: April 20 (pre-plant) Based on USDA Crop Profiles information located at http://pestdata.ncsu. edu/cropprofiles/

Application Type, and Depth of Incorporation (cm), CAM input turf: foliar/ground spray; 0 cm; CAM = 2 peanuts: band/ground spray; 0 cm; CAM = 1 cabbage: broadcast spray; 10 cm; CAM = 4 potatoes: granular; 10 cm; CAM = 4 cotton: in-furrow spray; 0 cm; CAM = 1 Reg. 5481-419 Reg. 5481-472 Reg. 400-453 Reg. 5481-450 Reg. 400-399
Soil Partition Coefficient (K d ; mL/g) 15.5 MRID 41648201; lowest non-sand K d Aerobic Soil Metabolism Half-life (days) t 1/2 = 1555 days (parent plus PCA) MRID’s 42911902, 41384501, 41713202, 42112801; represents the 90 th percentile of the upper confidence bound on the mean of 2 half-life values
Spray Drift Fraction (ground spray) 0.01 Input parameter guidance
Application Efficiency 0.99 Input parameter guidance
Molecular Weight 295.3 g/mole Product chemistry data
Vapor Pressure 1.13 x 10 -4 Torr Product chemistry data
Henry’s Law Constant 4.42 x 10 -5 atm-m 3 -mol Product chemistry data
Solubility in Water at 25 o C (ppm) 4.4 ppm set at 10X solubility limit of 0.44 ppm based on input parameter guidance
Aerobic Aquatic Metabolism Half-life (days) t 1/2 = 3110 days (parent plus PCA) input value is 2X the aerobic soil metabolism half-life input value as in input parameter guidance
Anaerobic Aquatic Metabolism Half-life (days) t 1/2 =1460 days (parent plus PCA) input value is 2X the anaerobic soil metabolism half-life value (as in input parameter guidance); calculated using

source data from MRID 41384301
Hydrolysis Half-life @ pH 7 (days) stable MRID’s 40865301, 40972601Parameter Value Source and/or Comments



### 134 Aquatic Photolysis Half-life @ pH 5 (days) 1.83 MRID’s 42606201, 42606202, 42336201
Estimated Drinking Water Concentrations
The EDWC’s for surface water bodies were determined using the Tier II screening-level simulation models PRZM (v. 3.12; input generated by PE4VO1.pl, dated 8/8/03) and EXAMS (2.98.04). The actual PRZM/EXAMS output/input files for the simulations on all uses modeled are presented as Attachment 1 . For additional information on PRZM and EXAMS, see http://www.epa.gov/oppefed1/models/water/

. For use in the human health risk assessment, EFED recommends an acute surface water EDWC of 440 ppb and a chronic EDWC of 65.5 ppb, both basedon the use of PCNB on turf at a rate of two applications of 32.67 lb a.i./A at a 21-day interv al. Note that the value “440 ppb” is the aqueous solubility limit of the parent compound at 25 o C. While the use of PCNB on (ornamental) bulb crops at an application rate of 213.4 lb a.i./A/application (single application) may result in higher values, EFED does not have a standard modeling scenario available to simulate application to (ornamental) bulb crops. The acute, chronic and 30-yr. average values for the five crops modeled are presented below in Table 3

.
Table 3. PRZM/EXAMS surface water EDWC result s for PCNB plus PCA for the drinking water assessment.

Crop PCA PRZM/EXAMS Results (ppb) acute 1-in-10 year 30-year average

Turf 1.0 440 1 65.50 33.73

Peanuts 0.87 195.1 13.87 7.04 Cabbage 0.87 164.6 14.28 7.73

Potatoes 0.87 27.80 2.53 1.47

Cotton 0.87 53.73 6.48 3.16

1 The actual output value from PRZM/EXAMS was 587.7 ppb for the turf us e acute concentration. However, as this is greater than the aqueous solubility of 440 ppb for PCNB, the sol ubility limit should be used instead.
The five agricultural or recreational (turf) uses of PCNB chosen to represent the use of the compound in the environment are turf, peanuts, cabba ge (cole crop), potatoes and cotton. To simulate these uses, EFED used a standard Pennsylvania turf scen ario, a standard North Carolina peanuts scenario, a standard Florida cabbage scenario, a standard Ida ho potatoes scenario, and a standard Mississippi cotton scenario. Application dates were chosen based on whether PCNB is applied as a pre- or post-emergent to the respective crops as well as on reported planting da tes found in the USDA agricultural crop profiles at www.pestdata.ncsu.edu/cropprofiles. The human drinking water EDWCs were determined using the standard index reservoir scenario in which a 172-ha field drains into a 52000 m 2 reservoir and percent cropped area (PCA) is taken into consideration. Th e PCA for each of the four crops modeled except turf is the default value of 0.87; a value of 1.0 is usedfor turf. Chemical property input values were chosen

### 135 according to the current EFED standard guidance document ( Input Parameters in Modeling the Environmental Fate and Transport of Pesticides, Version II , February 28, 2002).
The use of the Pennsylvania standard scenario is based on the registrant’s information that PCNB is used on turf (as a post-emergent), to prevent snowmold, mainly in the Great Lakes regions. An application date of November 15 thwas chosen to represent a post-emergent application (generally done prior to Thanksgiving) made during the part of the growing season in which snow mold occurs (November through April). Incorporation of the pes ticide was not modeled, as the application simulated was a post-emergent (foliar/ground) spray. The application rate and timing were obtained from a registered label (Reg. 5481-419).

The use of the Florida standard scenario for cabbage is based on the pesticide survey usage information that the crop with the highest usage in te rms of its total U.S. planted acres treated with PCNB is the cole crop brussel sprouts. However, b ecause EFED did not have a standard modeling scenario available for brussel sprouts, cabbage (which is treat ed at the same rate as brussel sprouts) was chosen as the representative cole crop. An application date of August 15 thwas chosen for a pre-plant application of PCNB based on a planting time of August to February in northeast Florida, where 50% of the state’s cabbage acreage is located. The application simulate d represents a ground spray with an incorporation to 10 cm. The application rate and depth of incorpor ation were obtained from a registered label (Reg. 400- 453). The use of a 10-cm incorporation depth ( vs . the 2.5-cm depth used in earlier modeling) resulted in lower EDWC’s for cabbage than in the previous Tier II DWA.
The use of the North Carolina peanuts and the Mississippi cotton standard scenarios are based on the registrant’s information that PCNB is used on tho se crops predominantly in the south. An application date of April 15 thwas chosen for a pre-plant application to peanuts based on a planting time of April 20 th to May 20 th . An application date of April 20 thwas chosen for a pre-plant application to cotton based on a May 1 stplanting time. The application simulated for both crops represents a ground spray with no incorporation. Although the application to cotton is in-furrow (T-band) and incorporation of some of the pesticide to 1⁄2-1 inch (the seeding depth) would occur, this type of application at such a shallow depth is best modeled as a broadcast with no incorporation (R.David Jones, EFED; Personal Communication 7/04 ). The application rates and depths of incorpor ation were obtained from respective registered labels (Reg. 5481-472 and Reg. 400-399).
The use of the standard Idaho potatoes scenario is based on the registrant’s information that PCNB is used on that crop mainly in the Pacific No rthwest and the Great Lakes regions. An application date of May 20 thwas chosen for a pre-plant application to potatoes based on a planting time of April to June 10 thfor eastern Idaho, where the majority of the crop is grown in the state. The application simulated represents a granular formulation with an incorporation to 10 cm. The application rate and depth of incorporation were obtained from a registered label (Reg. 5481-450).

### 136 Attachment 1. PRZM/EXAMS Outputs for the Drinking Water Assessment
Turf (Standard Pennsylvania Turf Scenario)

stored as turfdwa1.out Chemical: pcnb PRZM environment: PAturfC.txt modified Satday, 12 October 2002 at 17:27:02 EXAMS environment: ir298.exv modified Thuday, 29 August 2002 at 15:34:12 Metfile: w14737.dvf modified Wedday, 3 July 2002 at 09:06:12 Water segment concentrations (ppb)
Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 198 196 158 85.09 56.73 13.99 1962 275 272 262 238 187 50.5 1963 123 122 116 53.84 35.95 13.07 1964 328 324 312 281 216 64.79 1965 162 161 155 123 101 28.09 1966 113 112 104 58.09 46.75 18.63 1967 220 192 144 113 90.7 33.08 1968 74.89 74.29 71.94 60.88 49.85 19.52 1969 359 355 338 127 85.04 31.68 1970 329 326 314 302 241 66.48 1971 244 241 223 112 83.38 29.65 1972 73.3 64.03 48.74 35.48 28.77 12.43 1973 286 249 209 82.87 55.3 17.86 1974 640 554 341 134 104 48.49 1975 131 130 129 92.15 64.61 19 1976 430 425 405 170 113 45.36 1977 375 371 356 332 262 80.8 1978 268 265 255 247 196 57.6 1979 118 117 113 101 80.45 22.57 1980 128 110 85.52 53.35 35.59 10.07 1981 103 88.68 71.49 62.36 45.41 13.44 1982 157 155 149 141 108 29.05 1983 576 570 533 227 151 43.61 1984 545 539 517 359 250 65.58 1985 756 655 409 252 168 43.96 1986 283 280 272 255 203 58.8 1987 60.27 59.77 57.92 54.26 43.21 13.25 1988 589 509 335 205 136 37.76 1989 235 206 125 67.6 51.31 15.51 1990 83.44 72.94 45.66 23.13 16.81 7.207

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 756 655 533 359 262 80.8 0.0645161290322581 640 570 517 332 250 66.48 0.0967741935483871 589 554 409 302 241 65.58 0.129032258064516 576 539 405 281 216 64.79 0.161290322580645 545 509 356 255 203 58.8 0.193548387096774 430 425 341 252 196 57.6 0.225806451612903 375 371 338 247 187 50.5 0.258064516129032 359 355 335 238 168 48.49 0.290322580645161 329 326 314 227 151 45.36 0.32258064516129 328 324 312 205 136 43.96 0.354838709677419 286 280 272 170 113 43.61 0.387096774193548 283 272 262 141 108 37.76 0.419354838709677 275 265 255 134 104 33.08 0.451612903225806 268 249 223 127 101 31.68 0.483870967741936 244 241 209 123 90.7 29.65 0.516129032258065 235 206 158 113 85.04 29.05 0.548387096774194 220 196 155 112 83.38 28.09 0.580645161290323 198 192 149 101 80.45 22.57 0.612903225806452 162 161 144 92.15 64.61 19.52 0.645161290322581 157 155 129 85.09 56.73 19 0.67741935483871 131 130 125 82.87 55.3 18.63 0.709677419354839 128 122 116 67.6 51.31 17.86 0.741935483870968 123 117 113 62.36 49.85 15.51 0.774193548387097 118 112 104 60.88 46.75 13.99 0.806451612903226 113 110 85.52 58.09 45.41 13.44

### 137 0.838709677419355 103 88.68 71.94 54.26 43.21 13.25 0.870967741935484 83.44 74.29 71.49 53.84 35.95 13.07 0.903225806451613 74.89 72.94 57.92 53.35 35.59 12.43 0.935483870967742 73.3 64.03 48.74 35.48 28.77 10.07 0.967741935483871 60.27 59.77 45.66 23.13 16.81 7.207

0.1 587.7 552.5 408.6 299.9 238.5 65.501 Average of yearly averages: 33.7275666666667
Inputs generated by pe4.pl - 8-August-2003

Data used for this run: Output File: turfdwa1 Metfile: w14737.dvf PRZM scenario: PAturfC.txt EXAMS environment file: ir298.exv Chemical Name: pcnb Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42E-5 atm-m^3/mol Vapor Pressure vapr 1.13E-4 torr Solubility sol 4.4 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 3110 days Halfife Anaerobic Aquatic Metabolism kbacs 1460 days Halfife Aerobic Soil Metabolism asm 1555 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 2 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 36.59 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 15-11 dd/mm or dd/mmm or dd-mm or dd-mmm Interval 1 interval 21 days Set to 0 or delete line for single app. Record 17: FILTRA IPSCND 3 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR IR Flag for runoff calc. RUNOFF total none, monthly or total(average of entire run)

### 138 Peanuts (Standard North Carolina Peanuts Scenario)

stored as nutdwa1.out Chemical: pcnb PRZM environment: NCpeanutC.txt modified Satday, 12 October 2002 at 17:12:46 EXAMS environment: ir298.exv modified Thuday, 29 August 2002 at 15:34:12 Metfile: w13737.dvf modified Wedday, 3 July 2002 at 09:06:30 Water segment concentrations (ppb)
Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 155 133 85.97 49.31 37.69 11.78 1962 68.98 59.24 36.24 23.02 20.65 7.78 1963 369 325 193 85.09 58.55 18.02 1964 143 120 75.63 35.43 28.53 9.37 1965 53.71 44.67 24.24 13.33 9.817 3.124 1966 98.8 82.54 47.04 23.84 16.85 8.443 1967 79.22 68.17 39.69 32.48 23.75 7.975 1968 28.41 24.09 13.69 10.72 8.238 3.73 1969 110 99.87 62.63 33.01 28.12 8.761 1970 74.76 67.3 48.45 27.13 25.06 8.072 1971 46.48 39.86 24 18.96 14.87 6.284 1972 38.24 32.24 21.55 13.99 11.68 4.27 1973 110 93.2 51.28 26.83 26.79 9.087 1974 76.31 66.69 53.31 29.09 23.61 7.49 1975 232 194 107 54.28 43.19 16.4 1976 60.03 50.37 29.41 14.47 15.89 5.288 1977 63.53 54.09 34.36 18.94 13.82 6.889 1978 81.14 72.21 60.76 39.99 30.81 8.805 1979 109 94.38 71.97 43.15 30.44 9.642 1980 154 131 73.37 41.36 29.28 11.2 1981 79.06 69.54 40.42 24.36 20.45 7.023 1982 33.2 28.39 18.37 12.87 9.912 4.008 1983 115 97.08 53.94 29.3 21.57 6.91 1984 313 268 175 97.64 71.81 20.35 1985 65.97 55.54 41.58 21.99 18.6 7.163 1986 55.69 47.07 26.58 15.01 10.54 3.991 1987 92.68 77.38 45.67 24.19 17.37 6.919 1988 28.62 24.51 16.69 10.52 8.81 3.255 1989 38.78 32.93 23.68 14.95 14.62 5.684 1990 40.94 35.47 23.02 13.12 12.24 4.96

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 369 325 193 97.64 71.81 20.35 0.0645161290322581 313 268 175 85.09 58.55 18.02 0.0967741935483871 232 194 107 54.28 43.19 16.4 0.129032258064516 155 133 85.97 49.31 37.69 11.78 0.161290322580645 154 131 75.63 43.15 30.81 11.2 0.193548387096774 143 120 73.37 41.36 30.44 9.642 0.225806451612903 115 99.87 71.97 39.99 29.28 9.37 0.258064516129032 110 97.08 62.63 35.43 28.53 9.087 0.290322580645161 110 94.38 60.76 33.01 28.12 8.805 0.32258064516129 109 93.2 53.94 32.48 26.79 8.761 0.354838709677419 98.8 82.54 53.31 29.3 25.06 8.443 0.387096774193548 92.68 77.38 51.28 29.09 23.75 8.072 0.419354838709677 81.14 72.21 48.45 27.13 23.61 7.975 0.451612903225806 79.22 69.54 47.04 26.83 21.57 7.78 0.483870967741936 79.06 68.17 45.67 24.36 20.65 7.49 0.516129032258065 76.31 67.3 41.58 24.19 20.45 7.163 0.548387096774194 74.76 66.69 40.42 23.84 18.6 7.023 0.580645161290323 68.98 59.24 39.69 23.02 17.37 6.919 0.612903225806452 65.97 55.54 36.24 21.99 16.85 6.91 0.645161290322581 63.53 54.09 34.36 18.96 15.89 6.889 0.67741935483871 60.03 50.37 29.41 18.94 14.87 6.284 0.709677419354839 55.69 47.07 26.58 15.01 14.62 5.684 0.741935483870968 53.71 44.67 24.24 14.95 13.82 5.288 0.774193548387097 46.48 39.86 24 14.47 12.24 4.96 0.806451612903226 40.94 35.47 23.68 13.99 11.68 4.27 0.838709677419355 38.78 32.93 23.02 13.33 10.54 4.008 0.870967741935484 38.24 32.24 21.55 13.12 9.912 3.991 0.903225806451613 33.2 28.39 18.37 12.87 9.817 3.73

### 139 0.935483870967742 28.62 24.51 16.69 10.72 8.81 3.255 0.967741935483871 28.41 24.09 13.69 10.52 8.238 3.124

0.1 224.3 187.9 104.897 53.783 42.64 15.938 Average of yearly averages: 8.0891
Inputs generated by pe4.pl - 8-August-2003

Data used for this run: Output File: nutdwa1 Metfile: w13737.dvf PRZM scenario: NCpeanutC.txt EXAMS environment file: ir298.exv Chemical Name: pcnb Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42E-5 atm-m^3/mol Vapor Pressure vapr 1.13E-4 torr Solubility sol 4.4 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 3110 days Halfife Anaerobic Aquatic Metabolism kbacs 1460 days Halfife Aerobic Soil Metabolism asm 1555 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 1 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 11.2 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 15-04 dd/mm or dd/mmm or dd-mm or dd-mmm Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR IR Flag for runoff calc. RUNOFF total none, monthly or total(average of entire run)

### 140 Cabbage (Standard Florida Cabbage Scenario)

stored as cabdwa1.out Chemical: pcnb PRZM environment: FLcabbageC.txt modified Satday, 12 October 2002 at 16:39:00 EXAMS environment: ir298.exv modified Thuday, 29 August 2002 at 15:34:12 Metfile: w12842.dvf modified Wedday, 3 July 2002 at 09:04:28 Water segment concentrations (ppb)
Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 76.1 65.05 43.29 21.76 14.8 4.518 1962 145 126 86.59 58.76 41.37 11.61 1963 85.83 73.09 39.22 16.92 14.64 5.664 1964 153 135 94.52 51.2 35.3 10.82 1965 59.71 54.99 36.59 22.24 17.04 5.188 1966 48.14 42.27 26.11 16.67 12.83 4.292 1967 42.28 35.46 24.67 18.44 14.73 5.416 1968 126 113 77.37 47.03 37.73 11.52 1969 79.24 68.86 42.59 33.43 24.29 9.57 1970 65.08 55.69 43.6 23.52 16.12 5.077 1971 191 174 109 74.06 57.93 16.71 1972 173 150 117 60.82 43.73 12.39 1973 92.98 79.94 58.57 38.49 27.53 7.954 1974 53.55 48.44 30.35 17.34 12 4.151 1975 114 98.54 71.59 44.76 33.11 10.52 1976 119 103 63.91 38.36 27.22 7.74 1977 65.4 56.44 42.31 30.58 21.77 6.451 1978 35.38 31.17 19.07 14.59 12.59 4.749 1979 91.52 82.9 57.67 44.85 32.77 12.49 1980 60.9 53.06 41.83 26.25 18.46 5.517 1981 164 141 96.65 63.14 44.47 13.8 1982 135 118 82.75 57.62 42.28 12.72 1983 69.2 60.34 47.4 29.26 21.16 7.15 1984 89.26 78.61 57.31 35.11 25.43 7.111 1985 304 264 155 73.99 57.81 17.13 1986 58.52 51.97 37.57 25.28 21.94 7.589 1987 57.35 49.89 39.48 29.81 24.37 7.8 1988 212 185 125 86.86 60.78 17.19 1989 115 100 86.3 49.65 36.59 10.3 1990 36.99 33.14 20.73 11.51 10.06 3.405

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 304 264 155 86.86 60.78 17.19 0.0645161290322581 212 185 125 74.06 57.93 17.13 0.0967741935483871 191 174 117 73.99 57.81 16.71 0.129032258064516 173 150 109 63.14 44.47 13.8 0.161290322580645 164 141 96.65 60.82 43.73 12.72 0.193548387096774 153 135 94.52 58.76 42.28 12.49 0.225806451612903 145 126 86.59 57.62 41.37 12.39 0.258064516129032 135 118 86.3 51.2 37.73 11.61 0.290322580645161 126 113 82.75 49.65 36.59 11.52 0.32258064516129 119 103 77.37 47.03 35.3 10.82 0.354838709677419 115 100 71.59 44.85 33.11 10.52 0.387096774193548 114 98.54 63.91 44.76 32.77 10.3 0.419354838709677 92.98 82.9 58.57 38.49 27.53 9.57 0.451612903225806 91.52 79.94 57.67 38.36 27.22 7.954 0.483870967741936 89.26 78.61 57.31 35.11 25.43 7.8 0.516129032258065 85.83 73.09 47.4 33.43 24.37 7.74 0.548387096774194 79.24 68.86 43.6 30.58 24.29 7.589 0.580645161290323 76.1 65.05 43.29 29.81 21.94 7.15 0.612903225806452 69.2 60.34 42.59 29.26 21.77 7.111 0.645161290322581 65.4 56.44 42.31 26.25 21.16 6.451 0.67741935483871 65.08 55.69 41.83 25.28 18.46 5.664 0.709677419354839 60.9 54.99 39.48 23.52 17.04 5.517 0.741935483870968 59.71 53.06 39.22 22.24 16.12 5.416 0.774193548387097 58.52 51.97 37.57 21.76 14.8 5.188 0.806451612903226 57.35 49.89 36.59 18.44 14.73 5.077 0.838709677419355 53.55 48.44 30.35 17.34 14.64 4.749 0.870967741935484 48.14 42.27 26.11 16.92 12.83 4.518 0.903225806451613 42.28 35.46 24.67 16.67 12.59 4.292

### 141 0.935483870967742 36.99 33.14 20.73 14.59 12 4.151 0.967741935483871 35.38 31.17 19.07 11.51 10.06 3.405 0.1 189.2 171.6 116.2 72.905 56.476 16.419 Average of yearly averages: 8.88473333333333
Inputs generated by pe4.pl - 8-August-2003

Data used for this run: Output File: cabdwa1 Metfile: w12842.dvf PRZM scenario: FLcabbageC.txt EXAMS environment file: ir298.exv Chemical Name: pcnb Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42E-5 atm-m^3/mol Vapor Pressure vapr 1.13E-4 torr Solubility sol 4.4 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 3110 days Halfife Anaerobic Aquatic Metabolism kbacs 1460 days Halfife Aerobic Soil Metabolism asm 1555 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 4 integer See PRZM manual Incorporation Depth: DEPI 10 cm Application Rate: TAPP 33.6 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 15-08 dd/mm or dd/mmm or dd-mm or dd-mmm Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR IR Flag for runoff calc. RUNOFF total none, monthly or total(average of entire run)

### 142 Potatoes (Standard Idaho Potatoes Scenario)

stored as potdwa1.out Chemical: pcnb PRZM environment: IDpotatoC.txt modified Satday, 12 October 2002 at 17:00:44 EXAMS environment: ir298.exv modified Thuday, 29 August 2002 at 15:34:12 Metfile: w24156.dvf modified Wedday, 3 July 2002 at 09:04:38 Water segment concentrations (ppb)
Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 19.36 16.63 9.538 6.674 4.82 1.583 1962 10.3 8.845 5.081 2.401 1.96 1.191 1963 15.54 13.47 8.349 5.59 4.187 1.952 1964 10.74 10.66 6.017 3.595 3.546 1.508 1965 10.43 10.32 10.02 9.479 7.49 2.978 1966 10.63 9.101 5.144 2.283 1.561 0.5888 1967 11.23 10.17 6.515 4.822 3.525 1.004 1968 11.93 10.45 7.091 3.567 2.569 1.156 1969 11.04 9.567 5.66 4.277 2.998 1.198 1970 58.81 51.26 31.49 15.96 11.07 3.295 1971 16.71 14.54 9.095 5.151 4.133 2.314 1972 13.76 12.1 7.466 4.926 3.944 2.088 1973 10.25 8.739 4.889 2.634 2.495 1.303 1974 33.62 28.51 15.8 6.859 4.747 1.917 1975 13.75 11.75 6.787 3.462 2.61 1.303 1976 22.84 20.3 13.01 6.302 4.525 2.057 1977 12.4 10.64 6.131 3.032 2.074 0.7915 1978 14.67 12.51 7.212 3.215 2.187 1.058 1979 10.39 9.761 9.266 5.926 4.954 1.799 1980 24.28 24.08 23.14 12.82 8.805 3.834 1981 32.81 28.24 16.35 7.136 4.891 1.888 1982 10.86 10.78 9.565 5.269 4.247 2.21 1983 10.32 8.865 5.094 3.571 2.574 1.922 1984 10.45 8.786 5.742 4.695 4.322 2.087 1985 12.36 10.54 6.015 3.789 3.278 1.063 1986 13.34 11.68 9.112 5.186 3.793 1.423 1987 10.65 9.176 5.26 2.314 2.063 0.5899 1988 10.23 8.705 5.469 3.859 2.58 1.127 1989 15.03 12.94 8.804 5.818 5.1 1.882 1990 15.16 13.36 8.064 3.869 3.523 1.435

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 58.81 51.26 31.49 15.96 11.07 3.834 0.0645161290322581 33.62 28.51 23.14 12.82 8.805 3.295 0.0967741935483871 32.81 28.24 16.35 9.479 7.49 2.978 0.129032258064516 24.28 24.08 15.8 7.136 5.1 2.314 0.161290322580645 22.84 20.3 13.01 6.859 4.954 2.21 0.193548387096774 19.36 16.63 10.02 6.674 4.891 2.088 0.225806451612903 16.71 14.54 9.565 6.302 4.82 2.087 0.258064516129032 15.54 13.47 9.538 5.926 4.747 2.057 0.290322580645161 15.16 13.36 9.266 5.818 4.525 1.952 0.32258064516129 15.03 12.94 9.112 5.59 4.322 1.922 0.354838709677419 14.67 12.51 9.095 5.269 4.247 1.917 0.387096774193548 13.76 12.1 8.804 5.186 4.187 1.888 0.419354838709677 13.75 11.75 8.349 5.151 4.133 1.882 0.451612903225806 13.34 11.68 8.064 4.926 3.944 1.799 0.483870967741936 12.4 10.78 7.466 4.822 3.793 1.583 0.516129032258065 12.36 10.66 7.212 4.695 3.546 1.508 0.548387096774194 11.93 10.64 7.091 4.277 3.525 1.435 0.580645161290323 11.23 10.54 6.787 3.869 3.523 1.423 0.612903225806452 11.04 10.45 6.515 3.859 3.278 1.303 0.645161290322581 10.86 10.32 6.131 3.789 2.998 1.303 0.67741935483871 10.74 10.17 6.017 3.595 2.61 1.198 0.709677419354839 10.65 9.761 6.015 3.571 2.58 1.191 0.741935483870968 10.63 9.567 5.742 3.567 2.574 1.156 0.774193548387097 10.45 9.176 5.66 3.462 2.569 1.127 0.806451612903226 10.43 9.101 5.469 3.215 2.495 1.063 0.838709677419355 10.39 8.865 5.26 3.032 2.187 1.058 0.870967741935484 10.32 8.845 5.144 2.634 2.074 1.004 0.903225806451613 10.3 8.786 5.094 2.401 2.063 0.7915

### 143 0.935483870967742 10.25 8.739 5.081 2.314 1.96 0.5899 0.967741935483871 10.23 8.705 4.889 2.283 1.561 0.5888

0.1 31.957 27.824 16.295 9.2447 7.251 2.9116 Average of yearly averages: 1.68484
Inputs generated by pe4.pl - 8-August-2003

Data used for this run: Output File: potdwa1 Metfile: w24156.dvf PRZM scenario: IDpotatoC.txt EXAMS environment file: ir298.exv Chemical Name: pcnb Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42E-5 atm-m^3/mol Vapor Pressure vapr 1.13E-4 torr Solubility sol 4.4 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 3110 days Halfife Anaerobic Aquatic Metabolism kbacs 1460 days Halfife Aerobic Soil Metabolism asm 1555 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 4 integer See PRZM manual Incorporation Depth: DEPI 10 cm Application Rate: TAPP 28 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 20-05 dd/mm or dd/mmm or dd-mm or dd-mmm Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR IR Flag for runoff calc. RUNOFF total none, monthly or total(average of entire run)

### 144 Cotton (Standard Mississippi Cotton Scenario)

stored as cotdwa1.out Chemical: pcnb PRZM environment: MScottonC.txt modified Wedday, 22 January 2003 at 11:52:38 EXAMS environment: ir298.exv modified Thuday, 29 August 2002 at 15:34:12 Metfile: w03940.dvf modified Wedday, 3 July 2002 at 09:05:46 Water segment concentrations (ppb)
Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 45.89 41.23 29.15 26.02 22.53 8.605 1962 17.94 15.51 9.946 5.032 3.626 1.534 1963 31.56 27.31 16.04 8.345 5.882 2.051 1964 28.26 23.45 13 8.328 7.741 4.086 1965 36.91 31.1 17.61 7.978 5.645 1.661 1966 25.98 23.66 14.85 10.69 7.621 2.356 1967 85.01 73.05 48.97 30.61 23.88 7.263 1968 25.76 22.7 17.76 10.57 7.415 2.317 1969 9.316 8.009 4.627 2.472 1.878 0.7639 1970 27.31 23.56 18 14.93 13.12 5.604 1971 73.62 62.96 46.94 26.88 18.98 5.6 1972 14.42 12.56 9.318 4.661 3.304 1.148 1973 24.65 21.25 14.84 9.092 6.524 2.959 1974 25.7 21.64 12.08 7.605 5.744 2.324 1975 25.29 21.99 16.46 9.327 7.196 2.372 1976 52.95 45.87 35.26 22.9 19.1 6.307 1977 36.73 31.47 19.01 9.479 7.45 3.06 1978 20.58 18.49 15.81 8.496 6.114 1.947 1979 62.58 57.03 41.53 28.52 27.72 10.46 1980 53.63 47.26 33.37 21.62 15.74 4.665 1981 23.32 20.91 14.83 10.57 8.164 2.357 1982 41.9 36.4 26.91 23.93 18.84 7.468 1983 54.4 48.76 30.52 14.4 10.19 3.23 1984 15.12 12.9 7.542 4.216 3.473 1.418 1985 39.85 34.78 21.3 12.2 9.77 3.43 1986 40.36 34.71 23.63 12.72 9.391 2.736 1987 17.2 15.44 9.986 5.164 4.33 1.403 1988 24.03 21.02 13.5 9.995 9.034 4.293 1989 39.23 34.17 24.59 16.21 12.12 3.831 1990 23.18 19.9 12.03 7.928 5.677 1.836

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 85.01 73.05 48.97 30.61 27.72 10.46 0.0645161290322581 73.62 62.96 46.94 28.52 23.88 8.605 0.0967741935483871 62.58 57.03 41.53 26.88 22.53 7.468 0.129032258064516 54.4 48.76 35.26 26.02 19.1 7.263 0.161290322580645 53.63 47.26 33.37 23.93 18.98 6.307 0.193548387096774 52.95 45.87 30.52 22.9 18.84 5.604 0.225806451612903 45.89 41.23 29.15 21.62 15.74 5.6 0.258064516129032 41.9 36.4 26.91 16.21 13.12 4.665 0.290322580645161 40.36 34.78 24.59 14.93 12.12 4.293 0.32258064516129 39.85 34.71 23.63 14.4 10.19 4.086 0.354838709677419 39.23 34.17 21.3 12.72 9.77 3.831 0.387096774193548 36.91 31.47 19.01 12.2 9.391 3.43 0.419354838709677 36.73 31.1 18 10.69 9.034 3.23 0.451612903225806 31.56 27.31 17.76 10.57 8.164 3.06 0.483870967741936 28.26 23.66 17.61 10.57 7.741 2.959 0.516129032258065 27.31 23.56 16.46 9.995 7.621 2.736 0.548387096774194 25.98 23.45 16.04 9.479 7.45 2.372 0.580645161290323 25.76 22.7 15.81 9.327 7.415 2.357 0.612903225806452 25.7 21.99 14.85 9.092 7.196 2.356 0.645161290322581 25.29 21.64 14.84 8.496 6.524 2.324 0.67741935483871 24.65 21.25 14.83 8.345 6.114 2.317 0.709677419354839 24.03 21.02 13.5 8.328 5.882 2.051 0.741935483870968 23.32 20.91 13 7.978 5.744 1.947 0.774193548387097 23.18 19.9 12.08 7.928 5.677 1.836 0.806451612903226 20.58 18.49 12.03 7.605 5.645 1.661 0.838709677419355 17.94 15.51 9.986 5.164 4.33 1.534 0.870967741935484 17.2 15.44 9.946 5.032 3.626 1.418 0.903225806451613 15.12 12.9 9.318 4.661 3.473 1.403

### 145 0.935483870967742 14.42 12.56 7.542 4.216 3.304 1.148 0.967741935483871 9.316 8.009 4.627 2.472 1.878 0.7639 0.1 61.762 56.203 40.903 26.794 22.187 7.4475 Average of yearly averages: 3.63616333333333
Inputs generated by pe4.pl - 8-August-2003

Data used for this run: Output File: cotdwa1 Metfile: w03940.dvf PRZM scenario: MScottonC.txt EXAMS environment file: ir298.exv Chemical Name: pcnb Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42E-5 atm-m^3/mol Vapor Pressure vapr 1.13E-4 torr Solubility sol 4.4 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 3110 days Halfife Anaerobic Aquatic Metabolism kbacs 1460 days Halfife Aerobic Soil Metabolism asm 1555 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 1 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 2.24 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 20-04 dd/mm or dd/mmm or dd-mm or dd-mmm Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR IR Flag for runoff calc. RUNOFF total none, monthly or total(average of entire run)

### 146 APPENDIX D3. INITIAL (TIER 1) SCREENING-LEVEL DRINKING WATER ASSESSMENT OF 11/12/03

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDES, AND TOXIC SUBSTANCES

PC Code: 056502 DP BARCODE: 291286



### MEMORANDUM November 12, 2003

SUBJECT: 

### Pentachloronitrobenzene: Tier I Drinking Water EDWCs for Use in the Human Health Risk Assessment.
TO: Mohsen Sahafeyan, Chemist RRB2/HED (7509C)
FROM: Cheryl A. Sutton, Ph.D. Environmental Scientist ERBIV/EFED (7507C)
THRU:R. David Jones, Ph.D., Senior Agronomist ERBIV/EFED (7507C)
Elizabeth Behl, Branch Chief ERBIV/EFED (7507C)
This memo summarizes the Tier I estimated drinking water concentrations (EDWC) for pentachloronitrobenzene [PCNB; plus the degradate pentachloroaniline (PCA), as described below] in surface water and in groundwater for use in the human health risk assessment. The EDWC’s are summarized in Table 1. Because the surface water EDWC values (as estimated by FIRST) are controlled by the solubility of PCNB (440 μg L -1 

### ) rather than by the degradation rate, there is no difference the in EDWC whether PCA is included in the estimate or not. This may not hold if more refined assessments with PRZM and EXAMS are done. EFED used the screening model FIRST (FQPA Index Reservoir Sc reening Tool) to calculate the surface water EDWC’s and used the screening model SCI-GROW (Screening Concentrations in Ground Water) to calculate the groundwater EDWC. Because PCNB is a registered chemical already in use, a search for monitoring data was conducted; the results are discussed in a separate section below. Because monitoring data for PCNB ar e scarce and of limited value in terms of this assessment, they are presented only for their qualitative value; they were not used quantitatively in the drinking water assessment.

### 147 In response to a decision made by the MARC committee (27 May 2003; Final Decision), the EFED scientist was to conduct the drinking water assessment to account for the parent compound plus two PCNB degradates considered to be residues of concern, pentachloroaniline (PCA) and pentachlorophenol (PCP). Because PCP is a known carcinogen, it will be considered separately in this assessment. Because PCP was not monitored and/or detected in most of the submitted guideline studies, the evaluation of the compound in terms of its presence in drinking water as a result of PCNB use will be qualitative. To account for the degradate PCA, aerobic soil metabolism half-lives determined for the parent compound in the guideline studies were recalculated using concentration data for the parent compound plus PCA. Because separate aqueous photolysis data were not available for PCA, and the compound was not detected in the irradiated solutions initially containing the parent compound, the photolysis half-life used in the modeling was calculated using parent compound concentration data only. The lack of information on the photolysis rate of PCA comprises a small uncertainty surrounding the surface water EDWCs. For the input parameter values for soil adsorption (Koc 

### in SCI-GROW and K d 

### in FIRST), the reviewer used the soil adsorption coefficients determined only for the parent compound. Based on submitted data, however, the mobility of PCA is similar to that of the parent compound, in that both compounds are generally expected to adsorb to soil and organic matter and have a low leaching potential.
In general, PCNB is a persistent, volatile compound that will be immobile in most soils, but may have slight or even moderate mobility in coarser (sandy) soils, particularly those that are low in organic matter. While PCNB is expected to be persistent in aerobic environments, it is microbially degraded more rapidly (DT 50 

### 's of <30 days) in anaerobic environments. It is stable to hydrolysis and is effectively stable to photodegradation on soil, but appears (based on two submitted studies) to photodegrade fairly rapidly in water, with half-lives on the order of a few days or less. (While evidence of aqueous photodegradation of PCNB was not found in the literature, EFED found the submitted studies acceptabl e and, therefore, used the half-life values determined in those studies.) In field studies, the compound has been shown to dissipate more rapidly in the plots in which the pesticide was not incorporated, with a half-life range of 39-57 days versus a half-life range of 128-324 days fo r plots with incorporated PCNB. The major degradates of PCNB in the environment are PCA and pentachlorothioanisole (PCTA); minor degradates are pentachlorothioanisole sulfoxi de (PCTASO), pentachlorothioanisole sulfone (PCTASO 2 

### ), and pentachlorobenzene (PCB), which is also present as an impurity along with hexachlorobenzene (HCB). While PCP was detected in two of the submitted studies, there is not sufficient evidence (either from the submitted data or from published literature, as discussed later in this memo) that the compound will routinely be formed from PCNB in the environment.

Table 1. Tier I EDWCs for dr inking water risk assessment.

Surface water drinking water sources acute: 440 ug/L (ppb) 1 chronic: 440 ug/L (ppb)
Groundwater drinking water sources 30.6 ug/L (ppb) 2

1 Surface water EDWC’s (acute and chronic) are based on PCNB use on turf at 32.67 lb a.i./A/applica tion in two applications (tota l application rate of 65.34 lb a.i./A. Note that 440 ppb is the aqueous solubility limit of PCNB at 25 o C. 2 Groundwater EDWC’s are based on PCNB use on bulb crops at 213.4 lb a.i./A/app lication in a single application.

### 148 Estimated Drinking Water Concentrations
For the surface water and groundwater assessments, the application rates for turf (2 applications of 32.67 lb a.i./A/application), peanut s (2 applications of 10 lb a.i./A/application), cole crops (1 application of 30 lb a.i./A), potatoes (1 application of 25 lb a.i./A) and bulb crops (1 application of 213.4 lb a.i./A) were initially used, which represent the highest annual application rates on the labels (as presented in the Use Closure Memo for PCNB Reregistration of 1/23/03, amended 6/23/03) for soil or foliar appli cations of PCNB. Seed treatment usage rates were considered (after conversion to field app lication rates by multiplying by the typical seeding rates for each crop; rates were obtained from Appendix V of EFED’s 9/12/03 Ecological Risk Assessment for the Carboxin Reregistration Eleg ibility Decision), but did not result in field application levels greater than those for soil and foliar applications. The soil drench application scenario (applicable to many crops) was modeled to determine preliminary EDWC’s for such uses. While these values are reported here (in a separate table), they are to be considered preliminary values and should not be used in the human health risk assessment at this time. Prior to a final determination of EDWC’s associated w ith a soil drench use, it is necessary that EFED obtain additional information from the registrants regarding this use pattern. A summary of the model input parameter values used in FIRST to model soil and foliar applications is presented in Table 2. The FIRST output file is located in Attachment 1. A summary of the model input parameter values used in SCI-GROW to model soil and foliar applications is presented in Table 3. The SCI-GROW output file is located in Att achment 2. A table of the source data used to determine input parameter values is located in Attachment 3.
FIRST (v1.0) is a screening-level model designed to estimate the pesticide concentrations found in surface water for use in drinking water assessments. The model provides upper bound estimates of environmental concentrations (acute and chronic) in surface water drinking water sources (untreated) that might occur following the use of a pesticide. FIRST uses basic environmental fate data and pesticide label use and application information to estimate the EECs following the treatment of a 10-hectare field withsubsequent runoff into a reservoir (an Index Reservoir, based on Shipman City Lake in Illinois, a 13-acre lake 9-feet deep with a watershed area of 427 acres or 172.8 hectares) that undergoes two full turnovers annually. FIRST also uses a Percent Cropped Area (PCA) factor to adjust for the area within the watershed that is planted to the modeled crop. In the model, a single runoff event occurs two days after the last application and can move a maximum of 8% of the applied pesticide into the reservoir, with the amount dependent on the degradation and adsorption of the pesticide which occurs in the field prior to the event, any incorporation of the pe sticide at the time of application, and the PCA. The model also accounts for degradation and binding to sediment which may occur in the reservoir following the runoff event. Spray drift (resulting in direct deposition of the pesticide into the reservoir or indirect loading from spray drift landing on the feeding stream) in the model is equivalent to 16% of the applied for aerial application, 6.3% for orchard air blast application, and 6.4% for other ground spray application.
SCI-GROW2 is a regression-based, Tier 1 screening model that provides a groundwater exposure value to be used in determining the potential risk to human health from drinking water

### 149 contaminated with the pesticide. SCI-GROW2 estimates likely groundwater concentrations if the pesticide is used at the maximum allowable rate in areas where groundwater is vulnerable to contamination. Characteristics of such vulnerable areas include high rainfall, rapidly permeable soil, and a shallow aquifer. In most cases, a large majority of the use area will have groundwater that is less vulnerable to contamination than the areas used to derive the SCI-GROW2 estimate.

EFED recommends that the acute EDWC to be used in the human health risk assessment for surface water is 440 ppb, based on the use of PC NB on turf at an application rate of 32.67 lb a.i./A/application for two applications with an application interval of 21 days (total application rate of 65.3 lb a.i./A). It is noted that for a ll of the aforementioned crops modeled with soil/foliar applications (with total maximum application rates ranging from 20 to 213.4 lb a.i./A), the same acute EDWC’s (i.e., 440 ppb) were obtained. Note, also, that the value “440 ppb” is the aqueous solubility limit of the parent compound at 25 o 

### C. EFED recommends that the chronic EDWC to be used in the drinking water assessment for surface water is 440 ppb, also based on the use of PCNB on turf, as described previously. While th e use of PCNB on bulb crops at an application rate of 213.4 lb a.i./A/application with a single application and no incorporation resulted in the same chronic EDWC for surface water of 440 ppb, the same use (i.e., bulbs) only with incorporation to 6 inches resulted in a lower chronic EDWC of 328.6 ppb. For the purposes of comparison, EFED determined the acute and chronic surface water EDWC’s for parent PCNB only (without including PCA), using the turf appli cation scenario. The EDWC’s for parent only were 440 ppb for both acute and chronic exposures, indicating that the inclusion of PCA did not have an apparent effect on the surface water EDWC’s, as they were more significantly affected by the aqueous solubility limit of the compound.

EFED recommends that the EDWC to be used in the human health risk assessment for groundwater is 30.6 ppb, based on the use of PCNB on bulb crops at an application rate of 213.4 lb a.i./A, applied in a single application. For the purposes of comparison, EFED determined the groundwater EDWC for parent PCNB only (withoutincluding PCA), using the bulb application scenario. The EDWC for parent only was 13.0 ppb, indicating that the inclusion of PCA did have an effect on the groundwater EDWC.

### 150 Table 2. FIRST (v1.0) input parameter values a nd results for PCNB applied to various crops.

Parameter Value
Application Rate (lb a.i./A) turf: 32.67 potatoes: 25 peanuts: 10 bulb crops: 213.4 cole crops: 30
Number of Applications turf: 2 potatoes: 1 peanuts: 2 bulb crops: 1 cole crops: 1
Interval between Applications (days) turf: 21 potatoes: NA peanuts: 30 bulb crops: NA cole crops: Not Applicable (NA)
Soil Partition Coefficient (K d ; mL/g) 15.5 (MRID 41648201; lowest non-sand K d )
Aerobic Soil Metabolism Half-life (days) t 1/2 = 1555 days (parent plus PCA) (source data from MRID’s 42911902, 41384501, 41713202, 42112801) 1

Wetted in? No
Depth of Incorporation (inches) turf: 0 potatoes: 0 peanuts: 0 bulb crops: 0; 6 cole crops: 0
Method of Application turf: ground application of granular peanuts: ground application of granular

cole crops: ground spray (broadcast) potatoes: ground spray (broadcast) bulb crops: ground spray (broadcast); granular
Percent Cropped Area 0.87 (all crops modeled here)
Solubility in Water (mg/L or ppm) 0.44
Aerobic Aquatic Metabolism Half-life (days) t 1/2 = 3110 days (parent plus PCA) 1 (source data from MRID’s 42911902, 41384501, 41713202, 42112801) (input value is two times the aerobic metabolism half-life input value)
Hydrolysis Half-life @ pH 7 (days) stable
Aquatic Photolysis Half-life @ pH5 (days) 1.83
FIRST Results (Estimated Drinki ng Water Concentrations for surface water) Acute Concentration (ppb): 440 2 (all crops) Chronic Concentration (ppb): turf: 440.0 peanuts: 183.6 cole crops: 301.4 potatoes: 251.2 bulb crops: 440.0; 328.6 3

1 For the purposes of the drinking water assessm ent, half-lives were recalculated to acc ount for the parent plus the degradate PC A. The aerobic soil metabolism half-life used in the models represents the 90 thpercentile of the upper confidence bound on th e mean half-life fo r two soils. The aerobic aquatic metabolism half-life was de termined, in the absence of study data, by mulitiplyi ng the aerobic soil metabolism half-life model input value by two to account for the uncertainty associated with a lack of true aquatic metabolism study data. 2 Note that 440 ppb, the acute concentration for all scenarios modeled, is the aqueous solubility limit for PCNB at 25 o C. 3 Because FIRST does not allow directly for incorporation of a non-granular formulation (as is done for th is usage), the EDWC was also determined for this crop (2 nd value reported) using a granular formulation incorporated to 6 inches to represent the use of either a granular OR a non-granular formulation (F, WP or WSP) incorporated to 6 inches. The first value reported corresponds to a use scenario with no incorporation.

### 151 Table 3. SCI-GROW2 input parameter values and results for PCNB applied to various crops by soil or foliar applications only.

Parameter Value
Maximum Application Rate (lb a.i./A/application) turf: 32.67 peanuts: 10 cole crops: 30 potatoes: 25 bulb crops: 213.4
Maximum Number of Applications per Year turf: 2 (21-day interval) peanuts: 2 (30-day interval) cole crops: 1 potatoes: 1 bulb crops: 1
Aerobic Soil Metabolism Half-life (days) t 1/2 = 750.5 days (parent plus PCA; average of two values) 1
Organic Carbon Partition Coefficient (K oc ) 1588 (lowest value of four; based on parent compo und only) (MRID 41648201)

Results (Estimated Drinking Water Concentrations for groundwater, in ppb) turf: 9.38 peanuts: 2.87 cole crops: 4.31 potatoes: 3.59 bulb crops: 30.6

1 For the purposes of the drinking water assessm ent, half-lives were recalculated to acc ount for the parent plus the degradate PC A, as requested by the MARC. 

### Preliminary EDWC’s for a Soil Drench Use Scenario

To allow for a determination of EDWC’s for all of the potential label uses of PCNB, the soil drench application scenario (applicable to many crops) was modeled to determine preliminary EDWC’s for such uses. Although the application scenario is reported as a soil drench use on beans (dry type), a soil drench use on multiple other crops with the same application rate (i.e., 40.84 lb a.i./A/application) will yield the same values. The values are reported in Table 4 are to be considered preliminary values and should not be used in the human health risk assessment at this time. Prior to a final determination of EDWC’s associated with a soil drench use, it is necessary that EFED obtain additional information from the registrants on this use pattern, particularly with regard to drenching practices, time between drench and transplant, number of treatments, estimated amount of pesticide/formulated product not retained in the drenched container, and planting densities for transplants in the field. Please note that the preliminary values were determined with a usage scenario which included a single application of the pesticide. Although the label appears to allow for two applications (with a 28-day interval) per growing season at this rate, it is unclear as to when the applications would occur relative to the transplant to the field. Thus, at this time, EFED utilized a single application in the use scenario.

### 152 Table 4. Tentative Tier I EDWCs for drinking water based on a soil drench use scenario.

Surface water drinking water sources acute: 207.3 ug/L (ppb) 1 chronic: 62.9 ug/L (ppb)
Groundwater drinking water sources 5.9 ug/L (ppb)

1 Surface water and groundwater EDWC’s are based on PCNB use on bean s (dry-type) at 40.84 lb a.i./A/application in a single appli cation . Note that this application rate is the same as that used for multiple other crops with a so il drench application usage. Note also t hat 440 ppb is the aqueous solubility limit of PCNB at 25 o C. 

### Monitoring Data
NAWQA monitoring data are not available. Based on information contained in the USEPA’s Pesticides in Ground Water Database, A Compilation of Monitoring Studies: 1971- 1991, National Summary , PCNB is not found in groundwater at significant levels or frequencies. In sampling of 1708 wells, only three detections of PCNB occurred, at a range of 0.008–0.275 μg/L. Sampled wells which did not contain measurable levels of PCNB included 459 wells in California, 71 in Maine, 649 in Minnesota, 263 in Mississippi, 10 in Oregon and 188 in Texas. However, there is no related information available with regard to whether the monitoring sites corresponded with PCNB use sites or times of usage. Updated monitoring data from STORET are not available; it is no longer possible to query either the historical database (in the Legacy Data Center) or the new database (Modernized STORET) to obtain all detections of a specific compound.
To supplement the monitoring data available to EFED in-house, a literature search was conducted to obtain published information (generally post-1990 only) on the occurrences of PCNB and its degradates in the aquatic and terrestrial environments; information on the former are included below. PCNB and its major degradates PCA and PCTA have not been detected frequently in North America. The presence of PCA and PCTA in the environment are most likely a result of the use of PCNB. Detections of the potential degradate PCP in the environment cannot necessarily be attributed to its existence as a degradate of PCNB, but are most likely a result of its use as a pesticide (wood preservative). Similarly, detections of the degradate (and impurity in PCNB) PCB in the environment are most likely a result of its existence as a byproduct in the manufacture of other compounds or as a degradate of hexachlorobenzene (HCB), and its industrial uses.
In a groundwater monitoring study of 18 wells in three counties in California (July 1994–1995), PCNB was not detected (California EPA, 1995). In a review of multiple studies in which sampling was conducted in surface water and/or groundwater at golf courses, PCNB was monitored in surface water in an unspecified number of studies, but was not detected (Cohen et al., 1999).
The degradates PCA, PCB and PCP were monitored in the Mississippi River and many of its tributaries (Illinois, Missouri, Ohio, Arkans as, White, and Yazoo Rivers; Rostad et al., 1993). PCA was detected in the surface waters at multiple locations, at concentrations of 0.018-0.055 ng/L. PCB was detected in the Mississippi Rive r and two of its main tributaries, but was not

### 153 likely a result of PCNB use. Its presence was attributed to its existence as a degradate of HCB, as suggested by the concentration profiles of the two compounds. PCP was not found in any of the surface water samples.
In summary, monitoring data on PCNB are somewhat scarce and/or incomplete information is available. As such, the data may be taken at face value, but are not substantial enough to quantitatively incorporate into the drinking water assessment. Additionally, the data have limitations in that it is not clear in most cases whether the water bodies/wells monitored correspond with or were even targeted to co rrespond with PCNB usage in terms of location and/or time.
Pentachlorophenol
It was decided by the MARC committee that both pentachloroaniline (PCA) and pentachlorophenol (PCP) were both PCNB degradat es of concern in water. Thus, the drinking water assessment must take into account these degradates in addition to the parent compound. The degradate PCA was accounted for by the recalculation of the parent half-lives, as described previously in this memo. As aforementioned, the degradate PCP, a known carcinogen, must be considered independently of PCNB and PCA. In the submitted guideline studies, pentachlorophenol (PCP) was detected as a degr adate of PCNB in only two of the studies, an anaerobic soil metabolism study and a terrestrial field dissipation study. In the anaerobic soil metabolism study, PCP was first detected in the soil, at 0.28 ppm, immediately after the induction of anaerobic conditions at 30 days, and was 0.33 ppm at 90 days (60 days postflooding); in the water phase, PCP was 0.048 ppm at 60 days and 0.037 ppm at 90 days. [It is noted that, given current EFED modeling require ments, data from aerobic and anaerobic aquatic metabolism studies are generally considered more useful than data from the anaerobic soil metabolism studies.] In the terrestrial fiel d dissipation study in which PCP was detected, the compound was detected immediately after application at 0.022 ppm, increased with time to a maximum of 0.161 ppm by day 16, then decreased to 0.008 ppm by day 60, and was below the limit of quantification (LOQ; 0.005 ppm) by 120 days. The lack of detection of PCP in the second submitted anaerobic soil metabolism study and the other seven field dissipation studies does not indicate that the compound wasn’t present; it was simply not monitored in those studies. In a single aerobic soil metabolism study in which PCP was monitored, the compound was not detected.
As submitted data on PCP (specifically, as a degradate of PCNB) are lacking, the treatment of PCP in EFED’s Tier I assessment must be qualitative in nature. The conclusions presented here were drawn mainly from information obtained from the published literature, as cited where appropriate. Essentially, evidence that PCP is formed from PCNB during microbial degradation in soil has been found in the literature, but the weight of evidence is not substantial. EFED has indicated to SRRD that additional da ta on the microbial metabolism of PCNB in both aerobic and anaerobic soil/water systems are necessary for a more complete evaluation of the risks (particularly with regard to PC P) associated with the use of PCNB.

### 154 PCP has been reported to be a “major” degradate of PCNB when the compound is microbially metabolized in soil (Murthy & Kaufman, 1978; Motoyama et al., 2001). However, the term “major” was not defined in either of the publications and the second publication merely cited the first as the source of their information, as did other studies found in the literature. Thus, EFED’s fairly extensive literature search resulted in only one primary reference in which it was stated that PCP is a soil metabolite of PCNB. Attempts to contact the study authors or their successors at the (former) USDA Pesticide Degradation Laboratory were unsuccessful.
In the first publication (i.e., Murthy & Kaufman), the study authors were unable to quantify the amount of PCP formed, as they discarded the aqueous portion (which accounted for 8-16% of the 56-58% of the applied that was extracted from the soil samples, for a maximum possible level of 9.28% of the applied) of thei r extract following an organic extraction, and were therefore unable to analyze the aqueous phase for PCP. In subsequent investigations, the study authors were able to determine (through GLC and TLC) that PCP was the compound present in the aqueous phase of the soil extract, but did not attempt to quantify the residues.
In a study done in Japan, it appears that PCP was not detected in a volcanic ash soil which had been extensively treated in the past with PCNB and in which the parent compound was detected in the soil at 10.10 ppm (Ohsawa et al., 1984). However, the compound pentachloroanisole (PCAN), which is a methylated derivative of and can interconvert with PCP under certain conditions, was detected at 0.009 ppm. (Further interpretation of this study was hindered by the fact that much of the text was in Japanese and a translation was not available.) It has been suggested in the literature that PCAN is the product of the microbial degradation of PCP following that compound’s formation from PCNB by soil microbes (Murthy and Kaufman, 1978; Murthy et al., 1979). In a study of PC NB degradation by fungi, PCAN was detected (Mora-Torres et al., 1996). In a study on PCNB degradation by soil microbes native to France, neither PCP nor PCAN were observed; degradat es included only PCA and PCTA (Mora-Torres et al., 2000).
In a study of the metabolism of PCNB in anaerobic sediment in Japan, PCP was not identified as a degradate; degradates included pentachloroaniline, 2,3,4,5-tetrachloroaniline, 3,4,5-trichloroaniline, 3,5-dichloroaniline and 3-ch loroaniline (with 2-CA and 4-CA identified as intermediates; Susarla et al., 1996). Tetrachloroaniline has also been identified as a metabolite of PCNB in other studies (Mora-Torres et al., 1996).

These results indicate that there are conditions under which PCP can form in the environment, but does not form under all conditions. At this point in time, we do not have sufficient information to determine what conditions favor PCP formation and which do not. Nor is there sufficient information to quantify the amount and rate of formation of PCP from PCNB when PCP is produced. Consequently, EFED is unable to estimate how much PCP might occur in drinking water from PCNB use. EFED has indicated to SRRD that additional data on the microbial metabolism of PCNB in both aerobic and anaerobic soil/water systems are necessary for a more complete evaluation of the risks asso ciated with PCNB, particularly with regard to PCP.

### 155 Literature Cited
California EPA; Sampling for pesticide residues in California well water. 1995 Update of The Well Inventory Database in California. CA Environmental Protection Agency, Dept. of Pesticide Regulation, 10 th 

### Annual Report. (December 1995)
Cohen, S., A. Svrjcek, T. Durborrow, N. Lajan Barnes. Water quality impacts by golf courses. J. Environ.Qual. 28:798-809.
Mora-Torres, R., C. Grosset and J. Alary. Chromatographia 51:526-530 (2000).
Mora-Torres, R., C. Grosset, R. Steiman, and J. Alary. Liquid chromatography study of degradation and metabolism of pentachloronitrobenzene by four soil micromycetes. Chemosphere 33:683-692 (1996).
Motoyama, T., K. Kadokura, S. Tatsusawa, T. Ar ie, and I. Yamaguchi. Application of plant microbe systems to bioremediation. RIKEN Re. 42:35-38 (2001).
Murthy, N.B.K. and D.D. Kaufman. Degradation of pentachloronitrobenzene (PCNB) in anaerobic soils. J. Agric. Food Chem. 26:1151-1156. (1978).
Murthy, N.B.K., D.D. Kaufman and G.F. Fries. Degradation of pentachlorophenol (PCP) in aerobic and anaerobic soil. J. Environ. Sci. Health B14:1-14 (1979).
Ohsawa, K., T. Miyamoto, and I. Yamamoto. Residue analysis of pentachloronitrobenzene and its related compound ( sic ) in soils by mass fragmentography. J. Pestic. Sci. 9:339-345 (1984).
Rostad, C.E., W.E. Pereira and T.J. Leiker. 1999. Distribution and transport of selected anthropogenic lipophilic organic compounds associated with Mississippi River suspended sediment, 1989–1990. Archives of Environ. Contam. and Tox. 36:248–255.
Susarla, S., S. Masunaga and Y. Yonezawa. Transformation of chloronitrobenzenes in anaerobic sediment. Chemosphere 32:967-977 (1996).
USEPA. Pesticides in groundwater database. A compilation of monitoring studies: 1971-1991. National summary. USEPA/OPP/O PPTS. USEPA-734-12-92-001 (1992).

### 156 

### Attachment 1: FIRST File

RUN No. 1 FOR pcnb ON turf * INPUT VALUES *

-------------------------------------------------------------------- RATE (#/AC) No.APPS & SOIL SOLUBIL APPL TYPE %CROPPED INCORP ONE(MULT) INTERVAL Kd (PPB ) (%DRIFT) AREA (IN)

-------------------------------------------------------------------- 32.670( 65.036) 2 21 15.5 440.0 GRANUL( .0) 87.0 .0

FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

-------------------------------------------------------------------- METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (RESERVOIR) (RES.-EFF) (RESER.) (RESER.)

-------------------------------------------------------------------- 1555.00 2 N/A 1.83- 226.92 ****** 211.49

UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.0 AUG 1, 2001

-------------------------------------------------------------------- PEAK DAY (ACUTE) ANNUAL AVERAGE (CHRONIC) CONCENTRATION CONCENTRATION

-------------------------------------------------------------------- 440.000 440.000

### 157 

### Attachment 2: SCI-GROW File

SCIGROW VERSION 2.3 ENVIRONMENTAL FATE AND EFFECTS DIVISION OFFICE OF PESTICIDE PROGRAMS U.S. ENVIRONMENTAL PROTECTION AGENCY SCREENING MODEL FOR AQUATIC PESTICIDE EXPOSURE

SciGrow version 2.3 chemical:pcnb time is 10/20/2003 13:19:59

------------------------------------------------------------------------ Application Number of Total Use Koc Soil Aerobic rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

------------------------------------------------------------------------ 213.400 1.0 213.400 1.59E+03 750.5

------------------------------------------------------------------------ groundwater screening cond (ppb) = 3.06E+01 *************************************************************************

### 158 

### Attachment 3: General fate and physica l-chemical property source data for PCNB modeling.

PARAMETER VALUE
Chemical Name pentachloronitrobenzene Molecular Weight 295.3 Solubility (25 o C) 0.44 mg/L (440 ppb) Vapor Pressure (25 o C) 1.13 x 10 -4 mmHg Hydrolysis Half-life (pH 5, 7, 9; 25 o C) stable (MRID’s 40865301, 40972601) Aqueous Photolysis Half-life (pH 7) t 1/2 = 2.5 days (MRID’s 42606201, 42606202) t 1/2 = 26.8 hours (MRID 42336201) Soil Photolysis Half-life stable (MRID’s 41004801, 41713201)

Aerobic Soil Metabolism Half-life t 1/2 = 77, 189 days (parent only); t 1/2 = 489, 1012 days (parent plus PCA) 1 t 1/2 = 983, 1052 days (total residues) 2 (MRID’s 42911902, 41384501, 41713202, 42112801)

Anaerobic Soil Me tabolism Half-life t 1/2 = 9 days, <30 (DT 50 ; parent only); t 1/2 = 210, 410 days (parent plus PCA, PCP) t 1/2 = 268, 334 days (total residues) (MRID’s 41203602, 42094401, 41384301, 41686001, 41713202, 42112802) Organic Carbon Partition Coefficient (K oc ) 1588, 2912, 3870, 17508 (MRID 41648201) Soil Partition Coefficient (K d , mL/g) 7.3, 15.5, 19.1, 210 (MRID 41648201)

1 For the purposes of the drinking water assessm ent, half-lives were recalculated to accountfor the parent plus the degradates P CA and PCP, when monitored and detected. 2 For the purposes of the ecological assessmen t, half-lives were recalculated to account for total residues, inclusive of the parent plus the degradates PCA, PCTA, PCB, PCP, PCTASO, PCTASO 2 , and the manufacturing contaminant HCB.

### 159 

### APPENDIX D4. DRINKING WATER ASSESSMENT OF HCB AND PCB DPBARCODE: D243496 MEMORANDUM

SUBJECT: Drinking Water Assessment of HCB and PCB

FROM: James K. Wolf, Soil Scientist Environmental Risk Branch 3 Environmental Fate and Effects Division (7507C)

TO: Luis Suguiyama, Branch Chief Fungicide Branch Registration Division (7505C)

THRU: Michael R. Barrett, Chemist Environmental Risk Branch 3 Environmental Fate and Effects Division (7507C)
Daniel Rieder, Branch Chief Environmental Risk Branch 3 Environmental Fate and Effects Division (7507C)

DATE: April 24, 1998

CHEMICALS: Atrazine, clopyrilid, chlorothalonil, chlorpyrifos-methyl, dacthal, endosulfan, pentachloronitrobenzene (PCNB), pentachlorophenol, picloram, simazine

PC CODE #s: 80803, 117401, 81901, 59102, 78701, 79401, 56502, 63001(2,3), 5101, 80807

INTRODUCTION
The Environmental Fate and Effects Division (EFE D) has been requested to provide the Health Effects Division (HED) with a drinking water assessment for Hexachlorobenzene (HCB) and Pentachlorobenzene (PCB). A toxicological profile h as been recently (1996) prepared by the Agency of Toxic Substances and Disease Registry (ATSDR) for Hexachlorobenzene (USDHHS, 1996). This profile was prepared in accordance with guidelines developed by the ATSDR and USEPA. Included within this profile is an exposure assessment for drinking water cont aminated with HCB. The Division proposes to use the assessment presented in the Toxicological Profile for HCB. The EPA has previously addressed hexachlorobenzene in drinking water (USEPA, 1985) and exposure to HCB (USEPA, 1986). A recent search of the EPA STORET Database was also conducted fo r HCB and PCB and considered in this assessment.

SUMMARY
Hexachlorobenzene (HCB) and pentachlorobenzene (P CB) are both persistent (years) and relatively immobile in the environment. The major route of dissipation is through sorption to soil in the terrestrial environment and to sediment and suspended particulates (o rganic and inorganic) in water. It appears that

### 160 HCB and PCB contamination of ground water resour ces is relatively unlikely due to the high binding potential of both these chlorobenzene compounds. B ased upon monitoring data and fate properties it seems unlikely that long term HCB and PCB concentrations in surface water would exceed 10 ppt (0.01 : g/L). These chemicals although persistent will not remain in solution very long at high concentrations, as they become sorbed to suspended materials and bottom sedim ent. Higher concentrati ons have been reported in surface and ground water, but tend to be related to hazardous waste, and landfill sites, and suspended sediment. It should also be noted that while water concentrations tend to be very low, HCB and PCB will accumulate to bottom sediment and bioaccumulate in fish. Due to desorption kinetics or through the disturbance of sediments, it is possible that some of the time HCB and PCB will go back into the solution phase if equilibrium is disrupted.

BACKGROUND
Hexachlorobenzene (HCB) is a chlorinated hydr ocarbon that does not occur naturally. Pentachlorobenzene (PCB) is also a chlorinated hydrocarbon. The production of HCB (as an end-product) for industrial uses have decreased since the 1970's. HCB and PCB are also formed as by-products, or contaminants, during the manufacture of chemicals (solvents), other chlorine-containing compounds and pesticides. HCB produced as a by-product during the production of chlorinated chemicals was estimated to be between 2.47 to 4.91 million pounds in 1972 (USDHHS , 1996; after IARC, 1979). More recent estimates of amounts of HCB stored on site as a by-product or impurity range from 0.15 to 1.52 million pounds per year (USDHHS, 1996; after TRI93, 1995). Hexachlorobenzene w as a widely used pesticide until 1984. It appears several other registered products containing HCB were registered until 1989 with stocks available until 1990. PCB is also a degradation product of the pesticide PCNB.
The major releases of HCB are by discharges into air and water from its production as a by-product of chemical manufacture or from pesticide applications . It is also released by some waste incineration processes (USEPA, 1998a). According to the EPA’s Toxic Chemical Release Inventory, during 1987 to 1993, HCB releases to water totaled 1,287 pounds (USEPA, 1998a). The application of contaminated pesticides is also important means of releasing HCB and PCB into the environment.
Sources of hexachlorobenzene and pentachloroben zene from a “draft” of the Emissions Inventory of Section 112(c)(6) pollutants (from 1990) are listed in Table 1. Information concerning how inclusive these data are not yet available. Thus it is not entirely clear whether these are national estimates are only a subset of all sources. Based upon estimates given in Table 1, pesticide application only contributes, at a maximum, about 6 percent of the HCB in the environment. Based upon this information, the an ticipated PCB contributions would be much less.

Table 1. Summary of “Draft” Emissions Inventory Data for Pentachlorobenzene (PCB) and Hexachlorobenzene (HCB).

EMISSIONS SOURCE CATEGORY 1 PCB (tons/yr) PCB (~percent) HCB (tons/yr) HCB (~percent)
Chlorinated Solvents Production - 2 - 5.81e-01 25.26
Hazardous Waste Incineration 2.78e-02 17.38 - -
Industrial Oil Combustion 4.97e-05 0.03 - -
Medical Waste Incineration 4.03e-02 25.19 - - Municipal Waste Combustion 8.01e-02 50.06 - - Other Biological Incineration 2.49e-03 1.56 - - Pesticides Application - - 3 1.46e-01 ~6.35Table 1. Summary of “Draft” Emissions Inventory Data for Pentachlorobenzene (PCB) and Hexachlorobenzene (HCB).

EMISSIONS SOURCE CATEGORY 1 PCB (tons/yr) PCB (~percent) HCB (tons/yr) HCB (~percent)



### 161 Pesticides Manufacture - - 4.58e-01 19.91 Scrap or Waste Tire Combustion 1.04e-03 0.65 - - Sewage Sludge Incineration 5.12e-03 3.20 - - Tire Manufacturing - - 4.35e-01 18.91 Utility Coal Combustion - - 6.80e-01 29.57 Utility Oil Combustion 1.49e-04 0.09 - - Total Emissions (tons/yr) 0.16 98.16 ?? 100.00

1 Summary of draft 1990 Emission Inventory Data for Sec tion 112(C)(6) Pollutants (sources currently not available.
2 - No value provided.
3 Contaminant and degradation product of some pesticides, amount not specified

. 4 Difference from 100 is due rounding..
Table 2 lists the current (1998) maximum contaminan t levels (in percent) of HCB and PCB and the (available) product usage amounts for ten pesticides thathave HCB and/or PCB contaminants resulting from manufacturing. The estimated annual mass of HCB released to the environment based upon the amount of pesticides used and maximum percent contaminants per pound of pesticide is 6.5 tons/year compared to 0.146 tons/year estimated in Table 1. The amount PCB attribut ed to pesticide application is not stated in Table 1; PCB is a degradation product of the pesticide pent achloronitrobenzene (PCNB). The difference between Tables 1 and 2 may reflect the fact that the estimates in Table 2 assume that all of these pesticides contain the maximum percent of contaminates which may not to be the case. The potential for the total mass of HCB and PCB contaminants from pesticides is also notcomplete, since product usage information was not available for five of the pesticide. These additi onal pesticides are not expected to increase the mass significantly (since % contaminants are relatively low) unless usage is as great as atrazine, chlorothalonil, or simazine.

Table 2. Summary of Selected Pesticides with maximum percentage of hexachlorobenzene (HCB) and/or pentachlorobenzene (PCB) manufacturing contamination

.

Active Ingredient Maximum Contaminant (%) 1 Product Usage 2
HCB PCB (lbs ai for 1995)
Atrazine 1.70e-03 (1275 lbs) 2.50e-05 75,000,000
Clopyralid 8.00e-04 1.90e-04 not available
Chlorothanil 5.00e-02 (7500 lbs) -- 15,000,000
Chlorpyrifos-methyl 3 -- 4 3.00e-05 not available
Dacthal (DCPA) 3.00e-01 (4020 lbs) -- 1,340,000

Endosulfan 7.50e-05 6.00e-04 not available

PCNB 5.00e-02 1.00e-02 not available
Pentachlorophenol 7.50e-03 -- not available
Picloram 1.00e-02 (100 lbs) -- 1,000,000
Simazine 2.00e-03 (80 lbs) -- 4,000,000Table 2. Summary of Selected Pesticides with maximum percentage of hexachlorobenzene (HCB) and/or pentachlorobenzene (PCB) manufacturing contamination

.

Active Ingredient Maximum Contaminant (%) 1 Product Usage 2
HCB PCB (lbs ai for 1995)



### 162 Total 11,827.5 lbs (6.5 tons/year) 96,340,000 lbs (48,170 tons/year)

1 Obtained from HED, 2/10/98 and is assumed to be % relative to the mass of active ingredient..
2 Letter to L.Driver, EPA, from T. Gilding, ACPA, 11/27/96 concerning Emissions Inventory.
3 Indoor use.
4 Data not available.
PHYSICAL PROPERTIES, CHEMISTRY, AND ENVIRONMENTAL FATE
Chemical properties and environmental fate prope rties are summarized in Tables 3 and 4 for HCB and PCB, respectively. More information was available for HCB as compared to PCB. The fate data for both contaminants indicated that both are persistent in the environment with a high potential to sorb to soil particles and organic carbon. Representative fate values are presented below by compound.

HCB: Under most conditions, HCB is highly resistant to de gradation in soil, water, and air. When released to the atmosphere, HCB exists primarily in the vapor phase and degradation is extremely slow. Estimated atmospheric degradation half-lives range from 0.6 years to more than 6 years (USDHHS, 1996). HCB may be removed from the atmosphere via washout by precip itation, or by dry deposition. Atmospheric transport of HCB may be an important transport mechanism (Ke lly et al., 1991). HCB concentrations in the vapor phase represented 92 to 100 % of the total HCB concentr ation in air samples collected at a monitoring site in Ontario, Canada (Lane et al., 1992).
In water, HCB will partition from the water column into sediment and suspended particulates. It is not readily degraded by either abiotic or biotic pro cess in water. Half-lives are estimated to range from 2.7 to 5.7 years in surface water and 5.3 to 11.4 years in ground water (USDHHS, 1996). Volatilization from water is moderately rapid. Howeve r, due to strong sorption to particulates and the organic fraction, HCB is extremely persistent in sediment. Solubility in water ranges from 3.5 to 20 : g/L (Laseter et al. 1976, after USEPA, 1998b; USEPA, 1998a, USDHHS, 1996). Photodegrada tion of HCB also appears to be quite slow (USEPA, 1998a; USEPA, 1998b, USDHHS, 1996).
HCB volatilizes relatively rapidly from the soil surface. Because it is strongly sorbed to organic carbon (K oc range from 3,890 to 1,202,264), HCB is generally considered to be relatively immobile with respect to leaching. Information was not available to explain the wide range of K oc values. Half-lives in soils have been estimated to range between 3 to 6 years (USEPA, 1998a; USEPA, 1998b, USDHHS, 1996). In summary, HCB is a very persistent compound. HCB has a high affinity for lipophilic materials. It appears that photolysis, oxidation, hydrolysis, and bi odegradation have little effect on the fate HCB in the aquatic environment.

### 163 Table 3. Physical, chemical, and environmental fate properties of Hexachlorobenzene (Source of Information from USDHHS, 1996)

.

Property Value References cited from USDHHS, 1996

Molecular Formula C 6 Cl 6 Molecular Weight 284.78 Lide 1994
Melting Point 230 o C Verschueren 1983
Boiling Point 322 o C Verschueren 1983
Density @ 23.6 o C @ 23 o C 1.5691 2.044 Lide 1994 Merck 1989
Solubility in Water @ 20 o C @ ? 6.0 : g/L 3.5 : g/L Verschueren 1983 EPA OGWDW 1998
logK oc 5.22; 6.08; 3.59 (Strongly adsorbed to organic matter, considered immobile with respect to leaching.) Kenega and Goring, 1978; EPA, 1981 Kenega and Goring, 1978

Log O/W partition coef . 6.18 Verschueren 1983
Henry’s Law constant 6.84E-04 atm-m 3 /mol 1.30E-03 atm-m 3 /mol EPA, 1981 Atlas et al., 1982
Vapor Pressure@ 20 o C 1.089E-05 mm Hg Verschueren 1983

Persistence:

T 1/2 in atmosphere 0.63 yrs (tropics/subtropics) 1.94 yrs (temperate/boreal) 6.28 yrs (polar)

T 1/2 in surface water (~Rate: hrs -1 ) 2.7 to 5.7 yrs (2.931E-05/hr to 1.388E-05/hr)

T 1/2 in ground water (~Rate: days -1 ) 5.3 to 11.4 yrs (3.58E-04/d to 5.97E-08/d)

T 1/2 in soil (~Rate: days -1 ) 3 to 6 years (6.33E-04/d to 3.17E-04/d)

CHARACTERIZATION SUMMARY FOR HCB

Volatilization:
From water column HCB is volatilized moderately rapid, howev er, the strong adsorption can l ead to lengthy persistence in sediment.

From soil HCB can volatilize from the soil surface relatively quickly

Media Fate

### 164 In water HCB is persistent and not significantly degrad ed by either abiotic or biodegradation processes in water. It is resistant to the hydrolysis reactions, and not subject to photolytic decay.
HCB released to water will volatilize, adsorb to sediments or bioaccu mulate in fish and other aquatic organisms.

In soil and sediment HCB is persistent and is not significantly degraded in soils by either abiotic or biodegradation processes.
If released to soil, some HCB partitions to the atmosphere from soil surfaces through volatilization. The remainder is adsorbed strongly to soil where is persists for extended periods (months to years) due to resistance to biodegradation. Leaching is not anticipated due to the high adsorption characteristics.
HCB can volatilize from the soil surface relatively quickly.

PCB
Less chemistry data and environmental fate data were readily available for PCB (Table 4) as compared to HCB (Table 3). These data, however, suggest that PCB like HCB is persistent and not very mobile in the environment. It also appears less volatile than H CB, but based upon Henry’s low constant volatilization from water can still be important. The solubility of PCB, 1330.0 : g/L, is 38 to 222 times more soluble than HCB. The major source of dissipation appears to be sorpti on to soil particles and organic carbon and volatilization. As with HCB, PCB will bioaccumulate.

Table 4. Physical, chemical, and environmental fate properties of Pentachlorobenzene

.
Property Value References from USDAHHA, 1996 and OPTTS database search 1998

Mole Formula C 6 HCL 5 Mole Weight 250.32
Melting Point 86 o C SRC Recommended (Weast et al., 1985)
Boiling Point 277 o C (SRC Recommended (Weast et al., 1985)
LogP O/W 5.17 Hansch and Leo, 1985
Water Solubility 1,330 : g/L SRC Recommended (Banerjee et al., 1980).
Vapor Pressure 2.19E-03 mmHG@25 o C SRC Recommended (MacKay and Shiu, 1981).
Extrapolated from a liquid state from a T-range of 98.6 to 276.0

o C with fugacity correction.

Henry’s Law 4.89E-5 atm-cu/mol @ 22 o C 7.0E-04 atm-cu/mol @ 25 o C Hellmann, 1987
SRC Recommended (Oliver, 1985)

K oc 5450 3162 (K oc represents best or average value, as appropriate, back-calculated from log K oc ). 40000 Sabljic (1984) Koch et al (1983)

SRC Recommended (Karickhoff and Morris, 1985)Table 4. Physical, chemical, and environmental fate properties of Pentachlorobenzene

.



### 165 Persistence: Evidence suggests that it is persistent
Bioconcentration: Log Bioc Fact: Species: 4.22 Rainbow T. 3.55 Bluegill sunfish Oliver and Niimi (1983) Barrows et al (1980)
Hydrolysis Rate: 0.9 Half-life: 3208day @pH9 Ellington et al.(1988A)

MONITORING DATA
Monitoring Data From Toxicological Profile for HCB (USDHHS, 1996)
Monitoring data for HCB in atmosphere, soils, sed iment, and water are reported for a considerable time period (1971 - 1995) (USDHHS, 1996). It is my unde rstanding from discussions here at the Agency that pesticide manufacturers have reduced HCB and PCB cont aminant levels in some pesticides over this time. However, due the persistence of HCB (and PCB) in soil, sediments, and the atmosphere, the potential from exposure continues from previous HCB and PCB releases.
Atmosphere
Monitoring has focused in the Great Lakes region where the historical production of chlorobenzenes was high. HCB was also detected in precipitation up to 0.174 ng/L in the Great Lakes region (Oliver and Nichol, 1982). Recent air monitoring detected meanconcentrations greater or equal to 0.054 ng/m 3 in Ontario, Canada (Hoff et al. 1992).

Sediments and Soil

HCB has been detected in soil and sediment inboth agricultural areas where it was used as a fungicide on seed grains and in urban soils near pr oduction and waste disposal sites (Carey et al., 1985). HCB residues were detected in soils from 11 of 1,485 agricultural sites (0.7%) in 37 states with concentrations ranging from 10 to 440 ng/g), in 1972. In 1973, one of 1,470 sites (0.1%) contained HCB residues at 10 ng/g. Whether or not HCB was, use was not specified. A study in 1976 in 11 states, two of 391 sites (0.5%) had soil HCB at concentrations rangi ng from 10 to 20 ng/g (Carey et al., 1985). The author’s concluded that occurrence of HCB in the agricultural soils was associated with re gistered pesticide uses of HCB rather than environmental or industrial cont amination (USDHHS, 1996, after Carey et al., 1985). Detectable levels of HCB (10 to 590 ng/g) were found insoils sampled in seven of 40 urban areas, during the 1970's (USDHHS, 1996, after Carey et al., 1985). They concluded that HCB in the urban areas were attributed to releases from manufacturing, the use, or the disposal of HCB or HCB-containing waste rather than the use of hexachlo robenzene as a pesticide.

Mean concentrations of HCB in Great Lakes sediments have ranged between 0.2 and 97 ng/g (USDHHS, 1996; after Oliver and Nicol, 1982). HCB levels ranging from 0.5 to 460 ng/g were detected in 8-cm long sediment cores sampled in 1-cm segments. Deeper sediment core segments (1-2 cm) had higher concentrations (460 ng/g) than the surface (0-1 cm) segment (270 ng/g). The highest concentrations were attributed to sediment deposited during 1971 to 1976 (Oliv er and Nichol, 1982). They further reported that

### 166 the concentration of HCB in Lake Ontario sediment is 1 million times greater than HCB concentrations in Lake Ontario water.
HCB is expected to be immobile in soil, due to high sorption, and therefore unlikely to leach (USDHHS, 1996; after Swann et al., 1983). It is s uggested in the Toxicological Profile (USDHHS, 1996) that there is a potential for augmenting the leaching pr operties of HCB and other organochlorines. The lipid materials in bacterial cell membranes may lead to a repartitioning of hexachlorobe nzene sorbed to colloids. This could lead to a process called facilitated tran sport where the mobility of hydrophobic compounds such as HCB adsorbed to soils may be enhanced by biosorp tion on bacteria and move to aquifers along with the bioremedial bacterial cultures (Lindqvist and Enfiel d, 1992). Human exposure may also occur via dermal contact with contaminated soil or sediment or via ingestion of contaminated soil by children (USDHHS, 1996).

Water
Monitoring for HCB residues in surface and gr ound water are generally conducted in areas thought to have a potential for hexachlorobenzene contamination (e.g., industrial site or waste disposal site nearby). Limited monitoring appears to have been conducte d to assess pesticides as the source of HCB or PCB contamination. The Pesticides in Ground Water Data Base reports the collection of 1328 water samples for HCB (pesticide) in five states (CA, HI, MS, MT, and OR) (USEPA, 1992). HCB was detected in ground water in Mississippi. Four samples out of 263 samples collected in MS had HCB detections; concentrations ranged from 0.0039 to 0.0056 : g/L. The contamination was attributed to normal field use.
Much of the surface water monitoring for HCB have occurred in regions of the country where HCBs are more prevalent. Therefore, monitoring values w ould tend to provide “high” exposure concentrations. The mean concentration of HCB in drinking water for three cities on Lake Erie was 0.00001 : g/L (range 0.00006 to 0.0002 : g/L) (USDHHS, 1996; after Oliver and Nichol, 1982).

HCB was detected in two of the Great Lakes and thei r tributary rivers. Mean concentrations in Lake Ontario, Lake Huron, and the Grand River were 0.00006 : g/L (range, 0.00002-0.0001 : g/L), 0.00004 : g/L (range, 0.00002-0.0001 : g/L), and 0.00006 : g/L (range, 0.00002-0.0001 : g/L), respectively. In the Niagara River, concentrations ranging from 0.00002 to 0.017 : g/L were detected; the highest value was downstream from a waste disposal site (Oliver and Nichol, 1982). It was noted, by the study authors, that the widely variable concentrations in the Niagra River may have been attributed to the factthat the measurements were near the analytical detection limits. In more recent data, HCB was detected in 42% of whole water samples (dissolved plus particulate phases) collected during 1991 in the St. Lawrence River basin. The concentrations ranged from non-detect to 0.00009 : g/L (mean 0.00001 : g/L) (Quemerais et al., 1994) .
Water samples collected (in 1974-1975) from the Mississippi River, from areas of known hexachlorobenzene contamination in Louisiana, ranged from 2 to 90 : g/L (USEPA, 1976; Laska et al., 1976). Industrial waste water samples have reported HCB levels as high as 300 : g/L (USEPA, 1976; Schmitt, 1990). Some of these high values exceed the solubility of HCB (3.5 to 20 : g/L) in water; and therefore probably reflect the analysis of unfiltered water (includes soil and organic colloids), filtered water that still has some colloidal material, or the reported units are incorrect . Most likely the higher numbers reflect HCB in the water column and HCB sorbed to particulates or colloid al material in the water, rather than water alone.

### 167 Other Monitoring Data: STORET
Monitoring data obtained from STORET are briefl y discussed and presented below. STORET is a computerized database utility maintained by the O ffice of Water, EPA for the STOrage and RETrieval of chemical, physical, and biological data pertaining to th e quality of waterways within and contiguous to the United States. Geographical, political, and descriptive in formation concerning sites where data have been collected, known as “stations” are the base to which data is attached. The data contained in STORET are collected, stored, and used by a variety of Federal, State, Interstate, and local government agencies. These data are generally made freely available to every c itizen under the Freedom of Information Act (FOIA) or by direct access through a number of mechanisms.
The STORET data generally confirm that HCB a nd PCB concentrations in surface and ground water will be quite low, generally less than 0.01 : g/L . However, these monitoring data generally appear to represent sample that have not been filtered, and ther efore may have sorbed contaminates in the bulk water samples. This may also explain why some of the hi gher concentrations were reported. Monitoring results from some sites, such as the hazardous waste site in Alabama, represent sites with potentially higher exposure possibilities than those resulting fro m pesticide use (label rates).

Discussion
All data in STORET are owned by the user-agencies (data owners). Incoming data to the system are edited for errors and inconsistencies, however, the owners of the data have the primary responsibility for its content. Additionally, the STORET system imposes a structure and some minimum content requirements on incoming data, e.g., station identifier data, sample data temporal and spatial information, parametric data. Each agency which submits data to STORET manages its own data for its own purposes, and because their needs vary widely, the STORET data they maintain va ries widely from one agency to the next. Therefore, it is often recommended that prior to use of STOR ET data for regulatory purposes the circumstances under which it was collected be ascertained.
The STORET database includes a method category code (analysis description), water body type, sample medium, number of samples, reporting units, maximum and minimum values, and remark codes. Three major remark codes are K, U, and “blank” used provide information concerning the quality of the data. These codes instructs you how to inte rprete the STORET data. The K i ndicates that the value is “off-scale low”, the actual value is not known, but is known to be less than the value shown. The U indicates that the value was analyzed for, but not detected. The value reported is the limit of detection for the process used. The “blank” indicates that the value should be interpre ted exactly as reported. Other remark codes are W which indicates that the value observed is less thanthe lowest value reportable value under remark T. Remark T indicates the value is less than the “criteria” of detection. M indicates that the material was verified, but not quantified, and Q means sample was held beyond specified holding the time. Therefore, only the data with a “blank” remark code are considered in this assessment. The remaining data are, however, included in the Attachment.
Hexachlorobenzene monitoring data obtained from STORET are briefly discussed and summarized in Tables 5 (water) and 6 (sediments), respectively. Four method categories were indicated in STORET for the determination of HCB in water (39039, 39700, 82621, 34401). HCB residues were detected, under category 39700, in 73 samples with concen trations ranging between 0.00002 and 0.10 : g/L in lake water samples. For category 34401, HCB was detected in one stream sample, at 0.026 : g/L. Method category 39700 indicates whole water and not filtered water was analyzed, thus the measured HCB may include that

### 168 which is sorbed to suspended particulates or colloids in water, in addition to that which is dissolved. The remaining information for water samples is summari zed in Appendix Table A1. The significance of these data could not be evaluated, but are less than the va lue reported, with most of the listed values being much less than the maximum values being reported.
Several other limitations for interpreting monitoring data should be noted. M onitoring data is often limited by the lack of correlation between sampling date and the use patterns of the pesticide within the study’s drainage basin. Additionally, the sample locations were not associated with actual drinking water intakes for surface water nor were the monitored we lls associated with known ground water drinking water sources. Also, due to many different analytical det ection limits, no specified detection limits, or extremely high detection limits, a detailed interpre tation of the monitoring data is not always possible. A lack of data concerning the hydrogeology of the study sites also influences the interpretation of the monitoring data.
The maximum values reported for the HCB residues in sediments, bottom, etc. (Table 6) are much greater than those reported in water (Table 5). Th is agrees with the high potential for binding as indicated by the high sorption potential (high K oc s). Four category codes were also given to the samples used to determine HCB levels in sediments (39701, 49343, 75042, 78312). HCB residues were detected in 132 samples (Table 6), with concentrations ranging from 0.001 to 750 : g/kg (39701 and 78312), in lake sediments.

Table 5. Summary of hexachlorobenzene (H CB) monitoring data in water from STORET

.
Method Category Sample Data Quality Remark 1 Number of Samples Maximum ( : g/L) Minimum ( : g/L) Water Type

39700 2 Total 73 0.10 0.00002 Lake

34401 3 Dissolved 1 0.026 0.026 Stream

1 Data Quality Remark: The remark code is used to interprete the STORET data. A “blank” indicates that the value should be int erpreted exactly as reported.
2 39700 - Hexachlorobenzene in whole water.
3 34401 - Hexachlorobenzene in water, dissolved.

Table 6. Summary of hexachlorobenzene (HCB ) monitoring data in sediment from STORET

.
Method Category Medium Data QualityRem ark 1 Number of Samples Maximum ( : g/kg) Minimum ( : g/kg) Water Type

39701 2 Sed dry weight bottom 131 750.00 0.001 Lake

78312 3 Sed wet Weight core 2 2.00 0.90 Lake

1 Data Quality Remark: A “blank” in the rema rk code column indicates that the value should be interpreted exactly as reported.
2 37901 - Hexachlorobenzene in bottom deposits, dry solids.
3 78312 - Hexachlorobenzene in sediment, wet weight.
Of the four method categories described in STORET for analysis of PCB, only method 77793 (Table 7) measured PCB levels in water, the remaining me thods address sediment. For the samples designated with the “blank” remark, the surface water values are low, ranging between 0.00002 to 0.0001 : g/L. However, for well water samples, PCB concentrations ranged from 0.001 to 62.1 : g/L. These high values are associated with a “hazardous” waste site in Alabama. These values also appeared to have been measured with “whole” water, not filtered water. Thus, sorption of PCB to suspended particulates or colloidal material

### 169 in the water is possible (also probable given that th e maximum values exceed the solubility in water). The other three methods determine PCB levels in sediments (Table 8). The highest values, which far exceed the solubility, were found in stream sediment samples.

Table 7. Summary of pentachlorobenzene (P CB) monitoring data in water from STORET

.

Method Category Medium Data Quality Remark 1 Number of Samples Maximum ( : g/L) Minimum ( : g/L) Water type

77793 2 Total water 24 0.0001 0.00002 Stream

77793 Total water 51 0.0003 0.00001 Lake

77793 Total water 19 62.10 0.001 Well

1 Data quality remark: A “blank” in the remark code column indicat es that the value should be inte rpreted exactly as reported.
2 77793 - Pentachlorobenzene in whole water.

Table 8. Summary of pentachlorobenzene (P CB) monitoring data in sediment from STORET

.
Method Category Medium Data Quality Remark 1 Number of Samples Maximum ( : g/L) Minimum ( : g/L) Water type

39118 2 sediment 8 540000.0 40.00 Stream

79772 3 wet weight,

core 41 0.47 0.02 Stream

79790 4 dry weight, bottom 1 5.9 5.9 Stream

79772 wet weight,

core 2 0.00062 0.00029 Lake

1 Data quality remark: A “blank” in the remark code column indicat es that the value should be inte rpreted exactly as reported.
2 39118 - Pentachlorobenzene in sediment.
3 79772 - Pentachlorobenzene in sediment, wet weight.
4 79790 - Pentachlorobenzene in sediment, dry weight.

Fish and Game: HCB residues in commercial fish from the Great Lakes have been as high as 17 mg/kg (Newsome and Andrews, 1993; Zabik et al., 1995). C oncentrations have been reported as high as 700 mg/kg in fish samples collected in contaminated areas (Schmitt et al., 1990).

HEALTH ADVISORIES
The USEPA’s Office of Water has proposed sever al Health Advisories (HAs) for HCB. The proposed lifetime HA for children is 50 : g/L and for adults 200 : g/L (USEPA, 1997). The Cancer risk is defined as 2.00 : g/L at 10 -6 (USEPA, 1997). The EPA’s Office of Water has set the MCL for HCB at 1.00 : g/L (USEPA, 1997).

EXPOSURE ASSESSMENT

### 170 HCB and PCB contaminant levels in pesticides have generally declined since the 1970's, concomitant with declines in HCB releases into the environment. Ho wever, due the persistence of HCB (and PCB) in soil, sediments, and the atmosphere, the potential for exposur e from contaminated drinking water continues for previous HCB and PCB releases in addition to con tinuing releases. It appears that HCB and PCB contamination of ground-water resources is relatively un likely due to the high binding potential of both these chlorobenzene compounds. Detections of HCB in ground water generally have ranged between 0.00002 to 0.100 : g/L. Surface water detections show much more variability and have been measured at up to 750 : g/L. These high values appear to include sorbed HCB. The HCB concentrations which actually appear to be dissolved in the water tend to be generally less than 0.001 : g/L. Great Lakes region concentrations generally ranged from 0.00002 to 0.0001 : g/L, when concentrations exceeded this range, they appeared to related to industrial areas or contaminated areas more than 20 years ago.
Monitoring data is less prevalent for PCB than HCB. It is anticipated that the likelihood of exposure to PCB would to be less than that of HCB because of fe wer sources. Concentrations of PCB in surface water have ranged between 0.00002 and 0.0001 : g/L. PCB levels in ground water at a hazardous waste site ranged from 0.001 to 62.1 : g/L. PCB concentrations also tend be very low, 0.00002 to 0.001 : g/L, in unfiltered water samples.
Based upon these monitoring data and fate properti es it seems unlikely that long term HCB and PCB concentrations in surface and ground water would exceed 0.01 : g/L. Both of these chemicals although persistent will not remain in solution very long, as they become sorbed to suspend materials and bottom sediment.
The USDHHS (1996) estimates that the average e xposure in the United States from drinking HCB contaminated water is 0.00085 : g/kg/year (~ 0.000082 : g/L).
Drinking water systems are required to analyze water for HCB. The monitoring requirements are given in Table 9.

Table 9. HCB MONITORING REQUIREMENTS FOR GROUND WATER AND SURFACE WATER SOURCES (USEPA/OGWDW, 1998).

Sampling Frequency Number of samples
Initial Frequency 4 quarterlysamples every 3 years
Repeat Frequency If no de tection during initial round: 2 quarterly samples per yr if serving >3300 persons; 1 sample per 3 years for smaller systems
Triggers - Return to Initial frequency if detection at > 0.1 : g/L
The best available technology for treatment is activat ed granular charcoal. The high sorption indicated by the high K oc supports that this kind of treatment w ould greatly reduce HCB and PCB in water.

SELECTED REFERENCES
Carey, A.E., T.E. Dixon, H.S.C Yang. 1985. Envir onmental exposure to hexachlorobenzene in the United States. OPTS USEPA. Washington, DC.

### 171 Hoff, R.M. D.C.G. Muir, N.P. Grift. 1992. Annual cycle of polychlorinated biphenyls and organohalogen pesticides. Environ. Sci. Technol. 26:276-283.
Kelly, T.J., J.M. Czuczwa, P.R. Sticksel. 1991. Atmo spheric and tributary inputs of toxic substances to Lake Erie. J. Great Lakes Res. 17:504-516.
Lane, D.A., N.D. Johnson, M.J. Hanely. 1992. G as- and particle-phase concentrations of alphahexachlorocyclohexane, gamma-hexachlorocyclohexane, a nd hexachlorobenzene in Ontario air. Environ. Sci. Technol. 26:126-133.
Lindqvist, R. and C.G. Enfield. 1992. Biosorption of dichlor-diphenytrichlorethane and hexachlorobenzene in groundwater and its implicati ons for facilitated transport. A pplied and Environmental Microbiology 58:2211-2218.
Newsome, W.H., D. Davies, and J. Doucet. 1995. Organochlorine pesticides and polychlorinated biphenyl congener in commercial fish from the Great La kes. J. of AOAC International. 76:707-710.
Oliver, B.G. and K.D. Nicol. 1982. Chlorobenzen es in sediments, water, and selected fish from Lakes Superior, Huron, Erie, and Ontario. Environ. Sci. Technol. 16:532-536.
Quemerais, B., C. Lemieux, K.R. Lum. 1994. C oncentrations and sources of PCBs and organochlorine pesticides in the St. Lawrence River (Canda) and its tributaries. Chemosphere 29:591-610.
Schmitt, C.J., J.L. Zajicek, and P.H. Peterman. 1990. National contaminant biomonitoring program: Residues of organochlorine chemicals in U.S. fresh water fish, 1976-1984, Arch Environ Contam. Toxicol. 19:748-781.
Swann, R.L., D.A. Laskowski, P.J. McCall. 1983. A rapid method for the estimation of the environmental parameters octanol/water partition coefficient, soil sorp tion constant, water to air ratio, and water solubility. Residue Rev. 85:17-28.
TRI93. 1993. National Toxicology Information Program, Toxic Chemical Release Inventory. National Library of Medicine. Bethesda, MD.
USDHHS. 1996. Toxicological Profile for Hexachloroben zene (Update). U.S. Dept. of Health and Human Services. Public Health Service. Agency for Toxic Substances and Disease Registry. Division of Toxicological/Toxicology Information Branch. Atlanta, GA.
USEPA. 1985. Drinking Water Criteria document for hexachlorobenzene. USEPA. ODW, EPA/600/x84/1790-1. Washington, DC

USEPA. 1986. Exposure assessment for hexachlorobenzene. USEPA. OPPTS. EPA 560/5-86-019. Washington, DC

USEPA. 1992. Pes ticides in Ground Water Database. A compilation of monitoring studies: 1971- 1991 National Summary. EPA 734-12-92-001. U. S. Environmental Protection Agency: Arlington, VA.

### 172 USEPA. 1997. Drinking Water Standards and Health Advisories. USEPA Office of Water. Washington, DC

USEPA. 1998a. Technical Fact Sheet on He xachlorobenzene (HCB). 1/27/98. USEPA OGWDW (http://www.epa.gov./OGWDW/dwh/t-soc/hcb.html) Office of Water, Washington,DC.
USEPA. 1998b. Database search by OPPTS. USEPA. OPTS. Washington, DC. Zabik, M.E. and Rl Schemmel. 1980. Influence of diet on hexachloroben zene accumulation in Osborne Mendel rats. J. Environ. Pathol. Toxicol. 4:97-103.

### 173 Attachment. Remaining Hexachlorobenzene and pent achlorobenzene monitoring data roported in STORET.

Table A1. Summary of remaining hexachloroben zene (HCB) monitoring data in water from STORET

.
Method Category Sample Data Quality Remark 1 Number of Samples Maximum ( : g/L) Minimum ( : g/L) Water Type

39039 2 Water K 2 0.10 0.10 Lake

39700 3 Total K 11 0.80 0.010 Lake

39700 “ U 6 0.010 0.010 Lake

39700 “ K 502 100.00 0.000003 Lake

39700 “ T 1 10.00 10.00 Lake

39700 “ U 63 25.0 0.000 Lake

39700 “ W 15 10.00 10.00 Lake

82621 4 Total Recoverable K 1 0.02 0.02 Lake

39700 Total U 42 8.70 0.00 Ocean

34401 5 Dissolved K 16 5.00 0.006 Stream

34401 Dissolved M 25 0.018 0.007 Stream
34401 Dissolved Q 3 0.014 0.008 Stream

1 Remark: The remark codes K and U are used to interprete the STORET data. The K indi cates that the value is “off-scale low”, t he actual value is not known, but is know to be less than the value shown. The U i ndicates that the value was analyzed for, but not detected. Th e value reported is the limit of detection for the process used. Other remark codes are W which indicates that the valu e observed is less than the low est value reportable under remark T. Remark T indicates the value is less than the criteria of detection. M indicates that the material was verified, bu t not quantified and Q means sample was held beyond specified holding the time.

2 39039 - Hexachlorobenzene in water, electron capture.
3 39700 - Hexachlorobenzene in whole water.
4 82621 - Hexachlorobenzene in water, total recoverable.
5 34401 - Hexachlorobenzene in water, dissolved.

### 174 Table A2. Summary of hexachlorobenzene (HCB ) monitoring data in sediment from STORET

.

Method Category Medium Data Quality Remark 1 Number of Samples Maximum ( : g/kg; ng/g) Minimum ( : g/kg; ng/g) Water Type

39701 2 Sed dry weight bottom U 26 3.00 1.50 Lake
Sed dry weight bottom K 1231 2232.0 0.01 Lake
Sed dry weight bottom T 22 1.0 0.00 Lake
Sed dry weight bottom U 58 5000.0 0.00 Lake

49343 3 Sieved K 34 2220.00 1.00 Lake

75042 4 Sed dry Weight bottom U 1 47.5 47.5 Lake

78312 5 Sed wet Weight core K 11 350.0 0.70 Lake
39701 Sed dry weight K 1 5.00 5.00 Ocean
Sed dry weight U 63 1700.00 0.00 Ocean

1 Data Quality Remark: The several remark codes are K, U, and T are used to interprete the STOR ET data. The K indicates that th e value is “off-scale low”, the actual value is not known, but is know to be less than the value shown. The U indicates that the value was analyzed for, but not detected. The value reported is the limit of detection for the process used. Remark T indicates the value is less than the criteria of d etection.

2 39701 - Hexachlorobenzene in bottom deposits, dry solids.
3 49343 - Hexachlorobenzene in sediment, sieved, dry weight.
4 75042 - Hexachlorobenzene in sediment, dry weight.
5 78312 - Hexachlorobenzene in sediment, wet weight.

Table A3. Summary of pentachlorobenzene (P CB) monitoring data in water from STORET

.

Method Category Medium Data Quality Remark 1 Number of Samples Maximum ( : g/L) Minimum ( : g/L) Water type

77793 2 “ water K 85 20.00 0.000 Stream

“ water U 7 6.000 0.020 Stream

77793 “ “ K 1 0.000003 0.000003 Lake

77793 “ “ K 186 10.00 0.007 Well

“ “ U 20 50.00 0.001 Well

1 Data Quality Remark: Two remark codes are K and U are used to interprete the STORET data. Th e K indicates that the value is “off-scale low”, the actual value is not known, but is know to be less than the valu e shown. The U indicates that the value was analyzed for, b ut not detected. The value reported is the limit of de tection for the process used.

2 77793 - Pentachlorobenzene in whole water.

### 175 Table A4. Summary of pentachlorobenzene (P CB) monitoring data in sediment from STORET

.

Method Category Medium Data Quality Remark 1 Number of Samples Maximum ( : g/kg; ng/g) Minimum ( : g/kg; ng/g) Water type

39118 2 sediment K 138 13000.0 0.00 Stream

79790 3 dry weight, bottom U 1 250.0 250.0 Stream

dry weight,

bottom U 49 6.9 2.2 Stream

79772 4 dry weight, bottom U 1 250.0 250.0 Lake

39118 K 64 2247.2 0.000 Estuary
K 32 40.00 0 020 Estuary

39118 K 13 2183.0 0.000 Reservoir

K 1 0.020 0.020 Reservoir

1 Data Quality Remark: The three major remark codes are K and U are used to interprete the STORET data. The K indicates that th e value is “off-scale low”, the actual value is not known, but is know to be less than the value shown. The U indicates that the value was analyzed for, but not detected. The value reported is the limit of detection for the process used.

2 39118 - Pentachlorobenzene in sediment.
3 79772 - Pentachlorobenzene in sediment, wet weight.
4 79790 - Pentachlorobenzene in sediment, dry weight.

### 176 APPENDIX D5 PRZM/EXAMS OUTPUTS FOR ECOLOGICAL RISK ASSESSMENT 1. Cabbage (Standard FL Cabbage Scenario)
surface water numbers stored as ecocab1.out Chemical: pcnb PRZM environment: FLcabbageC.txt modified Satday, 12 October 2002 at 16:39:00 EXAMS environment: pond298.exv modified Thuday, 29 August 2002 at 16:33:30 Metfile: w12842.dvf modified Wedday, 3 July 2002 at 09:04:28 Water segment concentrations (ppb)
Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 40.76 35.7 24.65 12.65 8.72 2.561 1962 67.87 59.52 42.34 29.51 21.29 6.09 1963 35.61 30.92 17.67 8.483 7.544 3.21 1964 71.48 63.42 45.45 25.9 18.1 5.612 1965 26.42 24.47 16.9 12.26 9.892 3.041 1966 22.56 20.09 13.03 10.43 8.015 2.626 1967 23.56 21.7 17.23 11.21 8.835 3.101 1968 57.82 52.42 36.91 22.96 19.16 6.042 1969 35.75 31.52 21.89 18.25 13.44 5.196 1970 32.87 28.47 24.59 13.47 9.373 3.027 1971 84.37 77.17 50.52 36.8 29.13 8.514 1972 81.4 71.8 56.72 31.02 22.63 6.563 1973 42.97 37.48 29.45 20.39 14.76 4.364 1974 25.43 23.17 16.15 10.73 7.537 2.508 1975 51.54 45.02 33.58 22.71 17.43 5.525 1976 59.63 52.37 33.82 20.86 15.03 4.353 1977 34.77 30.4 22.67 17.09 12.42 3.717 1978 17.57 15.56 11.45 9.818 8.07 2.93 1979 40.83 37.37 27 23.28 17.44 6.544 1980 34.78 30.68 24.55 15.22 10.91 3.3 1981 76.32 66.74 47.1 31.8 23.05 7.228 1982 59.77 52.94 38.41 28.86 21.79 6.721 1983 33.25 29.41 23.38 16.62 12.24 4.11 1984 46.02 41.01 31.07 19.14 14.08 4.051 1985 131 115 70.5 36.23 28.49 8.674 1986 29.77 26.78 21.77 15.1 12.75 4.46 1987 31.96 28.24 21.82 15.95 13.47 4.361 1988 94.41 83.34 58.57 42.79 30.64 8.823 1989 53.1 47.22 41.51 25.79 19.36 5.669 1990 16.96 15.01 10.34 7.276 6.75 2.274

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 131 115 70.5 42.79 30.64 8.823 0.0645161290322581 94.41 83.34 58.57 36.8 29.13 8.674 0.0967741935483871 84.37 77.17 56.72 36.23 28.49 8.514 0.129032258064516 81.4 71.8 50.52 31.8 23.05 7.228 0.161290322580645 76.32 66.74 47.1 31.02 22.63 6.721 0.193548387096774 71.48 63.42 45.45 29.51 21.79 6.563 0.225806451612903 67.87 59.52 42.34 28.86 21.29 6.544 0.258064516129032 59.77 52.94 41.51 25.9 19.36 6.09 0.290322580645161 59.63 52.42 38.41 25.79 19.16 6.042 0.32258064516129 57.82 52.37 36.91 23.28 18.1 5.669 0.354838709677419 53.1 47.22 33.82 22.96 17.44 5.612 0.387096774193548 51.54 45.02 33.58 22.71 17.43 5.525 0.419354838709677 46.02 41.01 31.07 20.86 15.03 5.196 0.451612903225806 42.97 37.48 29.45 20.39 14.76 4.46 0.483870967741936 40.83 37.37 27 19.14 14.08 4.364 0.516129032258065 40.76 35.7 24.65 18.25 13.47 4.361 0.548387096774194 35.75 31.52 24.59 17.09 13.44 4.353 0.580645161290323 35.61 30.92 24.55 16.62 12.75 4.11 0.612903225806452 34.78 30.68 23.38 15.95 12.42 4.051 0.645161290322581 34.77 30.4 22.67 15.22 12.24 3.717 0.67741935483871 33.25 29.41 21.89 15.1 10.91 3.3 0.709677419354839 32.87 28.47 21.82 13.47 9.892 3.21 0.741935483870968 31.96 28.24 21.77 12.65 9.373 3.101 0.774193548387097 29.77 26.78 17.67 12.26 8.835 3.041

### 177 0.806451612903226 26.42 24.47 17.23 11.21 8.72 3.027 0.838709677419355 25.43 23.17 16.9 10.73 8.07 2.93 0.870967741935484 23.56 21.7 16.15 10.43 8.015 2.626 0.903225806451613 22.56 20.09 13.03 9.818 7.544 2.561 0.935483870967742 17.57 15.56 11.45 8.483 7.537 2.508 0.967741935483871 16.96 15.01 10.34 7.276 6.75 2.274

0.1 84.073 76.633 56.1 35.787 27.946 8.3854 Average of yearly averages: 4.83983333333333 Inputs generated by pe4.pl - 8-August-2003 Data used for this run: Output File: ecocab1 Metfile: w12842.dvf PRZM scenario: FLcabbageC.txt EXAMS environment file: pond298.exv Chemical Name: pcnb Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42E-5 atm-m^3/mol Vapor Pressure vapr 1.13E-4 torr Solubility sol 4.4 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 2248 days Halfife Anaerobic Aquatic Metabolism kbacs 2004 days Halfife Aerobic Soil Metabolism asm 1124 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 4 integer See PRZM manual Incorporation Depth: DEPI 10 cm Application Rate: TAPP 33.6 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 15-08 dd/mm or dd/mmm or dd-mm or dd-mmm Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Pond Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)

### 178 benthic numbers stored as ecocab1ben.out Chemical: pcnb PRZM environment: FLcabbageC.txt modified Satday, 12 October 2002 at 16:39:00 EXAMS environment: pond298.exv modified Thuday, 29 August 2002 at 16:33:30 Metfile: w12842.dvf modified Wedday, 3 July 2002 at 09:04:28 Benthic segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 7.3 7.294 7.173 6.549 5.885 1.873 1962 16.87 16.85 16.56 14.99 13.77 5.592 1963 6.865 6.86 6.744 5.807 5.31 3.406 1964 15.14 15.12 14.84 13.5 12.16 5.581 1965 7.56 7.555 7.466 6.923 6.291 3.35 1966 6.24 6.236 6.15 5.679 5.216 2.854 1967 6.807 6.801 6.675 6.172 5.918 2.968 1968 13.77 13.76 13.53 13.21 12.7 5.158 1969 10.78 10.77 10.61 9.749 9.035 5.391 1970 8.228 8.222 8.085 7.325 6.575 3.961 1971 21.24 21.23 21.03 20.2 18.63 7.177 1972 17.46 17.45 17.19 16.18 14.92 7.106 1973 11.89 11.88 11.68 10.65 9.702 4.863 1974 6.643 6.638 6.53 5.876 5.252 2.902 1975 14.11 14.1 13.88 12.87 11.85 4.878 1976 11.71 11.7 11.64 10.95 10.13 4.782 1977 9.697 9.691 9.555 8.781 8.064 3.757 1978 5.698 5.694 5.607 5.365 5.064 3.105 1979 14.17 14.16 13.95 12.67 11.6 5.965 1980 8.649 8.644 8.537 7.929 7.268 3.758 1981 18.56 18.54 18.27 16.71 15.39 6.536 1982 17.57 17.56 17.26 15.56 14.15 6.794 1983 9.714 9.709 9.577 8.784 8.035 4.552 1984 10.51 10.51 10.35 9.939 9.249 4.32 1985 22.26 22.25 22.08 20.57 19.34 7.402 1986 11.32 11.08 10.12 8.483 8.189 5.576 1987 9.526 9.519 9.356 8.895 8.471 4.326 1988 24.56 24.55 24.18 22.03 19.95 7.856 1989 14.86 14.85 14.65 13.72 12.65 6.415 1990 7.255 7.124 6.547 5.392 4.756 3.109

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 24.56 24.55 24.18 22.03 19.95 7.856 0.0645161290322581 22.26 22.25 22.08 20.57 19.34 7.402 0.0967741935483871 21.24 21.23 21.03 20.2 18.63 7.177 0.129032258064516 18.56 18.54 18.27 16.71 15.39 7.106 0.161290322580645 17.57 17.56 17.26 16.18 14.92 6.794 0.193548387096774 17.46 17.45 17.19 15.56 14.15 6.536 0.225806451612903 16.87 16.85 16.56 14.99 13.77 6.415 0.258064516129032 15.14 15.12 14.84 13.72 12.7 5.965 0.290322580645161 14.86 14.85 14.65 13.5 12.65 5.592 0.32258064516129 14.17 14.16 13.95 13.21 12.16 5.581 0.354838709677419 14.11 14.1 13.88 12.87 11.85 5.576 0.387096774193548 13.77 13.76 13.53 12.67 11.6 5.391 0.419354838709677 11.89 11.88 11.68 10.95 10.13 5.158 0.451612903225806 11.71 11.7 11.64 10.65 9.702 4.878 0.483870967741936 11.32 11.08 10.61 9.939 9.249 4.863 0.516129032258065 10.78 10.77 10.35 9.749 9.035 4.782 0.548387096774194 10.51 10.51 10.12 8.895 8.471 4.552 0.580645161290323 9.714 9.709 9.577 8.784 8.189 4.326 0.612903225806452 9.697 9.691 9.555 8.781 8.064 4.32 0.645161290322581 9.526 9.519 9.356 8.483 8.035 3.961 0.67741935483871 8.649 8.644 8.537 7.929 7.268 3.758 0.709677419354839 8.228 8.222 8.085 7.325 6.575 3.757 0.741935483870968 7.56 7.555 7.466 6.923 6.291 3.406 0.774193548387097 7.3 7.294 7.173 6.549 5.918 3.35 0.806451612903226 7.255 7.124 6.744 6.172 5.885 3.109 0.838709677419355 6.865 6.86 6.675 5.876 5.31 3.105 0.870967741935484 6.807 6.801 6.547 5.807 5.252 2.968

### 179 0.903225806451613 6.643 6.638 6.53 5.679 5.216 2.902 0.935483870967742 6.24 6.236 6.15 5.392 5.064 2.854 0.967741935483871 5.698 5.694 5.607 5.365 4.756 1.873 0.1 20.972 20.961 20.754 19.851 18.306 7.1699 Average of yearly averages: 4.84376666666667
Inputs generated by pe4.pl - 8-August-2003

Data used for this run: Output File: ecocab1 Metfile: w12842.dvf PRZM scenario: FLcabbageC.txt EXAMS environment file: pond298.exv Chemical Name: pcnb Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42E-5 atm-m^3/mol Vapor Pressure vapr 1.13E-4 torr Solubility sol 4.4 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 2248 days Halfife Anaerobic Aquatic Metabolism kbacs 2004 days Halfife Aerobic Soil Metabolism asm 1124 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 4 integer See PRZM manual Incorporation Depth: DEPI 10 cm Application Rate: TAPP 33.6 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 15-08 dd/mm or dd/mmm or dd-mm or dd-mmm Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Pond Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)

### 180 2. Cotton (Standard Mississippi Cotton Scenario)
surface water numbers

stored as ecocot1.out Chemical: pcnb PRZM environment: MScottonC.txt modified Wedday, 22 January 2003 at 11:52:38 EXAMS environment: pond298.exv modified Thuday, 29 August 2002 at 16:33:30 Metfile: w03940.dvf modified Wedday, 3 July 2002 at 09:05:46 Water segment concentrations (ppb)
Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 20.63 18.97 14.97 13.68 11.63 4.837 1962 8.103 7.214 5.03 2.818 2.108 0.9677 1963 13.3 11.78 7.473 4.085 2.994 1.112 1964 12.36 10.54 6.321 4.115 3.88 2.152 1965 15.22 13.14 7.976 3.874 2.819 0.9219 1966 11.55 10.76 7.347 5.48 4.054 1.31 1967 36.3 32.04 23.06 15.34 12.21 3.869 1968 11.33 10.15 8.428 5.441 3.958 1.306 1969 3.895 3.427 2.142 1.185 0.9315 0.4284 1970 12.12 10.93 9.03 7.489 6.559 2.981 1971 31.68 27.92 22.46 14.01 10.22 3.153 1972 6.373 5.695 4.527 2.481 1.854 0.6566 1973 10.73 9.494 7.095 4.686 3.497 1.594 1974 11.45 9.929 6.073 3.972 3.102 1.302 1975 11.28 10.06 7.805 4.784 3.766 1.317 1976 23.05 20.52 16.84 11.66 9.951 3.474 1977 16.25 14.33 9.395 5.065 4.006 1.697 1978 9.568 8.556 7.56 4.43 3.294 1.115 1979 28.22 26.26 20.34 14.83 13.99 5.788 1980 23.09 20.95 16.12 11.44 8.634 2.785 1981 9.972 9.07 6.915 5.162 4.134 1.291 1982 17.96 16.08 13.18 11.7 9.579 3.968 1983 23.67 21.53 14.21 7.378 5.346 1.826 1984 6.681 5.851 3.716 2.211 1.84 0.796 1985 16.9 15.08 9.975 5.83 4.86 1.809 1986 17.49 15.42 11.04 6.365 4.839 1.529 1987 7.432 6.704 4.682 2.557 2.237 0.7943 1988 10.3 9.284 6.563 5.171 4.602 2.296 1989 16.89 15.11 11.65 8.249 6.372 2.186 1990 10.32 9.103 5.977 4.115 3.069 1.036

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 36.3 32.04 23.06 15.34 13.99 5.788 0.0645161290322581 31.68 27.92 22.46 14.83 12.21 4.837 0.0967741935483871 28.22 26.26 20.34 14.01 11.63 3.968 0.129032258064516 23.67 21.53 16.84 13.68 10.22 3.869 0.161290322580645 23.09 20.95 16.12 11.7 9.951 3.474 0.193548387096774 23.05 20.52 14.97 11.66 9.579 3.153 0.225806451612903 20.63 18.97 14.21 11.44 8.634 2.981 0.258064516129032 17.96 16.08 13.18 8.249 6.559 2.785 0.290322580645161 17.49 15.42 11.65 7.489 6.372 2.296 0.32258064516129 16.9 15.11 11.04 7.378 5.346 2.186 0.354838709677419 16.89 15.08 9.975 6.365 4.86 2.152 0.387096774193548 16.25 14.33 9.395 5.83 4.839 1.826 0.419354838709677 15.22 13.14 9.03 5.48 4.602 1.809 0.451612903225806 13.3 11.78 8.428 5.441 4.134 1.697 0.483870967741936 12.36 10.93 7.976 5.171 4.054 1.594 0.516129032258065 12.12 10.76 7.805 5.162 4.006 1.529 0.548387096774194 11.55 10.54 7.56 5.065 3.958 1.317 0.580645161290323 11.45 10.15 7.473 4.784 3.88 1.31 0.612903225806452 11.33 10.06 7.347 4.686 3.766 1.306 0.645161290322581 11.28 9.929 7.095 4.43 3.497 1.302 0.67741935483871 10.73 9.494 6.915 4.115 3.294 1.291 0.709677419354839 10.32 9.284 6.563 4.115 3.102 1.115 0.741935483870968 10.3 9.103 6.321 4.085 3.069 1.112 0.774193548387097 9.972 9.07 6.073 3.972 2.994 1.036 0.806451612903226 9.568 8.556 5.977 3.874 2.819 0.9677

### 181 0.838709677419355 8.103 7.214 5.03 2.818 2.237 0.9219 0.870967741935484 7.432 6.704 4.682 2.557 2.108 0.796 0.903225806451613 6.681 5.851 4.527 2.481 1.854 0.7943 0.935483870967742 6.373 5.695 3.716 2.211 1.84 0.6566 0.967741935483871 3.895 3.427 2.142 1.185 0.9315 0.4284

0.1 27.765 25.787 19.99 13.977 11.489 3.9581 Average of yearly averages: 2.00993
Inputs generated by pe4.pl - 8-August-2003

Data used for this run: Output File: ecocot1 Metfile: w03940.dvf PRZM scenario: MScottonC.txt EXAMS environment file: pond298.exv Chemical Name: pcnb Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42E-5 atm-m^3/mol Vapor Pressure vapr 1.13E-4 torr Solubility sol 4.4 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 2248 days Halfife Anaerobic Aquatic Metabolism kbacs 2004 days Halfife Aerobic Soil Metabolism asm 1124 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 1 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 2.24 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 20-04 dd/mm or dd/mmm or dd-mm or dd-mmm Interval 1 interval days Set to 0 or delete line for single app. Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Pond Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)

### 182 benthic numbers

stored as ecocot1ben.out Chemical: pcnb PRZM environment: MScottonC.txt modified Wedday, 22 January 2003 at 11:52:38 EXAMS environment: pond298.exv modified Thuday, 29 August 2002 at 16:33:30 Metfile: w03940.dvf modified Wedday, 3 July 2002 at 09:05:46 Benthic segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 11.34 11.34 11.27 10.92 10.56 5.593 1962 4.445 4.378 4.081 3.542 3.171 2.124 1963 3.156 3.154 3.112 2.85 2.579 1.236 1964 3.357 3.355 3.31 3.227 3.132 2.183 1965 2.343 2.341 2.314 2.131 1.933 1.101 1966 4.185 4.182 4.122 3.755 3.504 1.772 1967 15.23 15.22 15.1 14.14 13.25 5.649 1968 5.252 5.249 5.195 4.821 4.434 2.249 1969 0.8439 0.8434 0.8328 0.7647 0.6943 0.4501 1970 6.023 6.02 5.942 5.575 5.265 3.431 1971 14 13.99 13.79 12.79 11.72 5.32 1972 2.546 2.545 2.511 2.312 2.106 1.108 1973 3.862 3.86 3.812 3.513 3.238 1.702 1974 4.819 4.782 4.743 4.449 4.168 2.187 1975 3.868 3.866 3.815 3.597 3.381 1.718 1976 8.074 8.07 7.979 7.733 7.396 3.69 1977 7.435 7.43 7.323 6.645 6.015 3.052 1978 3.443 3.441 3.4 3.142 2.885 1.457 1979 12.2 12.19 12.1 11.63 11.03 5.868 1980 12.19 12.18 12.06 11.35 10.52 5.041 1981 3.481 3.479 3.433 3.194 3.064 1.602 1982 8.942 8.938 8.834 8.276 7.826 4.467 1983 7.059 7.054 6.954 6.33 5.696 2.95 1984 2.252 2.25 2.223 2.084 1.963 1.137 1985 4.025 4.023 3.963 3.712 3.532 1.6 1986 4.777 4.774 4.72 4.4 4.061 2.064 1987 2.167 2.166 2.138 1.978 1.831 1.015 1988 4.195 4.192 4.168 4.104 3.975 2.458 1989 8.356 8.351 8.241 7.905 7.435 3.752 1990 3.922 3.92 3.879 3.608 3.252 1.561

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 15.23 15.22 15.1 14.14 13.25 5.868 0.0645161290322581 14 13.99 13.79 12.79 11.72 5.649 0.0967741935483871 12.2 12.19 12.1 11.63 11.03 5.593 0.129032258064516 12.19 12.18 12.06 11.35 10.56 5.32 0.161290322580645 11.34 11.34 11.27 10.92 10.52 5.041 0.193548387096774 8.942 8.938 8.834 8.276 7.826 4.467 0.225806451612903 8.356 8.351 8.241 7.905 7.435 3.752 0.258064516129032 8.074 8.07 7.979 7.733 7.396 3.69 0.290322580645161 7.435 7.43 7.323 6.645 6.015 3.431 0.32258064516129 7.059 7.054 6.954 6.33 5.696 3.052 0.354838709677419 6.023 6.02 5.942 5.575 5.265 2.95 0.387096774193548 5.252 5.249 5.195 4.821 4.434 2.458 0.419354838709677 4.819 4.782 4.743 4.449 4.168 2.249 0.451612903225806 4.777 4.774 4.72 4.4 4.061 2.187 0.483870967741936 4.445 4.378 4.168 4.104 3.975 2.183 0.516129032258065 4.195 4.192 4.122 3.755 3.532 2.124 0.548387096774194 4.185 4.182 4.081 3.712 3.504 2.064 0.580645161290323 4.025 4.023 3.963 3.608 3.381 1.772 0.612903225806452 3.922 3.92 3.879 3.597 3.252 1.718 0.645161290322581 3.868 3.866 3.815 3.542 3.238 1.702 0.67741935483871 3.862 3.86 3.812 3.513 3.171 1.602 0.709677419354839 3.481 3.479 3.433 3.227 3.132 1.6 0.741935483870968 3.443 3.441 3.4 3.194 3.064 1.561 0.774193548387097 3.357 3.355 3.31 3.142 2.885 1.457 0.806451612903226 3.156 3.154 3.112 2.85 2.579 1.236 0.838709677419355 2.546 2.545 2.511 2.312 2.106 1.137

### 183 0.870967741935484 2.343 2.341 2.314 2.131 1.963 1.108 0.903225806451613 2.252 2.25 2.223 2.084 1.933 1.101 0.935483870967742 2.167 2.166 2.138 1.978 1.831 1.015 0.967741935483871 0.8439 0.8434 0.8328 0.7647 0.6943 0.4501 0.1 12.199 12.189 12.096 11.602 10.983 5.5657 Average of yearly averages: 2.65123666666667
Inputs generated by pe4.pl - 8-August-2003

Data used for this run: Output File: ecocot1 Metfile: w03940.dvf PRZM scenario: MScottonC.txt EXAMS environment file: pond298.exv Chemical Name: pcnb Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42E-5 atm-m^3/mol Vapor Pressure vapr 1.13E-4 torr Solubility sol 4.4 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 2248 days Halfife Anaerobic Aquatic Metabolism kbacs 2004 days Halfife Aerobic Soil Metabolism asm 1124 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 1 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 2.24 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 20-04 dd/mm or dd/mmm or dd-mm or dd-mmm Interval 1 interval days Set to 0 or delete line for single app. Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Pond Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)

### 184 3. Peanuts (Standard North Carolina Peanuts Scenario)
surface water numbers

stored as econut1.out Chemical: pcnb PRZM environment: NCpeanutC.txt modified Satday, 12 October 2002 at 17:12:46 EXAMS environment: pond298.exv modified Thuday, 29 August 2002 at 16:33:30 Metfile: w13737.dvf modified Wedday, 3 July 2002 at 09:06:30 Water segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 65.39 57 38.7 23.19 17.93 5.819 1962 29.02 25.25 16.09 10.6 9.748 3.864 1963 154 136 84.54 39.26 27.44 8.704 1964 58.73 49.94 32.6 16.03 12.71 4.518 1965 22.36 18.8 10.54 5.988 4.483 1.622 1966 42.41 35.83 21.1 11.39 8.273 4.096 1967 32.86 28.61 17.37 14.6 10.9 3.949 1968 12.15 10.49 6.283 4.993 4.177 1.968 1969 46.15 41.97 27.34 14.67 12.8 4.277 1970 31.47 28.67 21.37 12.61 11.78 4.068 1971 19.26 16.72 10.51 8.538 6.73 3.12 1972 17.51 15.02 10.73 6.999 5.927 2.195 1973 47.41 40.95 23.81 12.91 12.67 4.457 1974 32.46 28.7 23.04 12.85 10.68 3.612 1975 101 84.2 46.7 24.85 19.87 7.684 1976 25.16 21.44 12.78 6.557 7.184 2.6 1977 27.71 23.97 15.84 9.336 6.998 3.394 1978 36.31 32.69 27.64 18.82 14.82 4.389 1979 47.47 42.17 32.69 20.37 14.84 4.784 1980 65.14 56.52 33.11 19.29 14.14 5.44 1981 33.13 29.44 17.77 10.87 9.243 3.433 1982 14.04 12.17 8.144 5.751 4.544 2.034 1983 50.64 43.52 25.64 14.52 10.83 3.499 1984 134 117 81.52 46.85 34.91 10.02 1985 27.79 23.7 18.3 10 8.49 3.442 1986 24.95 21.48 13 7.798 5.543 2.046 1987 40.26 33.8 20.48 11.49 8.384 3.302 1988 12.74 11.1 7.879 5.056 4.463 1.685 1989 17.46 15.15 10.49 6.808 6.654 2.836 1990 17.3 15.17 10.09 6.011 5.522 2.486

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 154 136 84.54 46.85 34.91 10.02 0.0645161290322581 134 117 81.52 39.26 27.44 8.704 0.0967741935483871 101 84.2 46.7 24.85 19.87 7.684 0.129032258064516 65.39 57 38.7 23.19 17.93 5.819 0.161290322580645 65.14 56.52 33.11 20.37 14.84 5.44 0.193548387096774 58.73 49.94 32.69 19.29 14.82 4.784 0.225806451612903 50.64 43.52 32.6 18.82 14.14 4.518 0.258064516129032 47.47 42.17 27.64 16.03 12.8 4.457 0.290322580645161 47.41 41.97 27.34 14.67 12.71 4.389 0.32258064516129 46.15 40.95 25.64 14.6 12.67 4.277 0.354838709677419 42.41 35.83 23.81 14.52 11.78 4.096 0.387096774193548 40.26 33.8 23.04 12.91 10.9 4.068 0.419354838709677 36.31 32.69 21.37 12.85 10.83 3.949 0.451612903225806 33.13 29.44 21.1 12.61 10.68 3.864 0.483870967741936 32.86 28.7 20.48 11.49 9.748 3.612 0.516129032258065 32.46 28.67 18.3 11.39 9.243 3.499 0.548387096774194 31.47 28.61 17.77 10.87 8.49 3.442 0.580645161290323 29.02 25.25 17.37 10.6 8.384 3.433 0.612903225806452 27.79 23.97 16.09 10 8.273 3.394 0.645161290322581 27.71 23.7 15.84 9.336 7.184 3.302 0.67741935483871 25.16 21.48 13 8.538 6.998 3.12 0.709677419354839 24.95 21.44 12.78 7.798 6.73 2.836 0.741935483870968 22.36 18.8 10.73 6.999 6.654 2.6 0.774193548387097 19.26 16.72 10.54 6.808 5.927 2.486

### 185 0.806451612903226 17.51 15.17 10.51 6.557 5.543 2.195 0.838709677419355 17.46 15.15 10.49 6.011 5.522 2.046 0.870967741935484 17.3 15.02 10.09 5.988 4.544 2.034 0.903225806451613 14.04 12.17 8.144 5.751 4.483 1.968 0.935483870967742 12.74 11.1 7.879 5.056 4.463 1.685 0.967741935483871 12.15 10.49 6.283 4.993 4.177 1.622

0.1 97.439 81.48 45.9 24.684 19.676 7.4975 Average of yearly averages: 3.9781
Inputs generated by pe4.pl - 8-August-2003

Data used for this run: Output File: econut1 Metfile: w13737.dvf PRZM scenario: NCpeanutC.txt EXAMS environment file: pond298.exv Chemical Name: pcnb Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42E-5 atm-m^3/mol Vapor Pressure vapr 1.13E-4 torr Solubility sol 4.4 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 2248 days Halfife Anaerobic Aquatic Metabolism kbacs 2004 days Halfife Aerobic Soil Metabolism asm 1124 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 1 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 11.2 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 15-04 dd/mm or dd/mmm or dd-mm or dd-mmm Interval 1 interval days Set to 0 or delete line for single app. Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Pond Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)

### 186 benthic numbers

stored as econut1ben.out Chemical: pcnb PRZM environment: NCpeanutC.txt modified Satday, 12 October 2002 at 17:12:46 EXAMS environment: pond298.exv modified Thuday, 29 August 2002 at 16:33:30 Metfile: w13737.dvf modified Wedday, 3 July 2002 at 09:06:30 Benthic segment concentrations (ppb)
Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 18.5 18.48 18.2 17.17 16.1 7.105 1962 12.85 12.84 12.64 11.41 10.98 5.927 1963 35.36 35.34 34.76 31.35 28.02 11.38 1964 11.7 11.69 11.53 10.53 9.501 5.263 1965 5.256 5.252 5.17 4.866 4.535 2.735 1966 16.47 16.41 16.17 14.75 13 6.3 1967 9.869 9.861 9.76 8.984 8.394 4.864 1968 5.752 5.748 5.657 5.414 5.077 2.958 1969 11.97 11.97 11.77 10.78 9.788 4.934 1970 12.83 12.83 12.67 11.79 11.46 6.053 1971 8.021 8.014 7.831 6.963 6.299 4.22 1972 9.315 9.308 9.134 8.301 7.646 3.864 1973 20.17 20.15 19.79 17.95 16.7 7.594 1974 9.946 9.944 9.803 8.986 8.169 4.28 1975 45.39 44.94 44.49 40.31 35.66 15.65 1976 8.646 8.638 8.47 7.481 7.247 4.138 1977 12.59 12.58 12.37 11.32 10.12 5.087 1978 18.07 18.06 17.76 16.84 15.77 6.925 1979 21.58 21.56 21.23 19.28 17.26 7.539 1980 18.82 18.8 18.46 16.47 14.74 7.437 1981 7.644 7.638 7.515 7.127 6.885 3.946 1982 4.726 4.722 4.643 4.222 4.041 2.706 1983 15.9 15.89 15.67 14.41 12.99 5.544 1984 70.57 70.52 69.18 62.76 56.79 21.91 1985 10.73 10.72 10.54 9.594 8.976 5.138 1986 9.312 9.284 8.98 8.332 7.414 3.546 1987 16.03 16.02 15.64 14.19 12.67 5.604 1988 6.031 6.026 5.945 5.53 5.221 2.648 1989 6.718 6.705 6.502 6.185 6.034 3.724 1990 5.493 5.489 5.401 4.896 4.57 2.957

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 70.57 70.52 69.18 62.76 56.79 21.91 0.0645161290322581 45.39 44.94 44.49 40.31 35.66 15.65 0.0967741935483871 35.36 35.34 34.76 31.35 28.02 11.38 0.129032258064516 21.58 21.56 21.23 19.28 17.26 7.594 0.161290322580645 20.17 20.15 19.79 17.95 16.7 7.539 0.193548387096774 18.82 18.8 18.46 17.17 16.1 7.437 0.225806451612903 18.5 18.48 18.2 16.84 15.77 7.105 0.258064516129032 18.07 18.06 17.76 16.47 14.74 6.925 0.290322580645161 16.47 16.41 16.17 14.75 13 6.3 0.32258064516129 16.03 16.02 15.67 14.41 12.99 6.053 0.354838709677419 15.9 15.89 15.64 14.19 12.67 5.927 0.387096774193548 12.85 12.84 12.67 11.79 11.46 5.604 0.419354838709677 12.83 12.83 12.64 11.41 10.98 5.544 0.451612903225806 12.59 12.58 12.37 11.32 10.12 5.263 0.483870967741936 11.97 11.97 11.77 10.78 9.788 5.138 0.516129032258065 11.7 11.69 11.53 10.53 9.501 5.087 0.548387096774194 10.73 10.72 10.54 9.594 8.976 4.934 0.580645161290323 9.946 9.944 9.803 8.986 8.394 4.864 0.612903225806452 9.869 9.861 9.76 8.984 8.169 4.28 0.645161290322581 9.315 9.308 9.134 8.332 7.646 4.22 0.67741935483871 9.312 9.284 8.98 8.301 7.414 4.138 0.709677419354839 8.646 8.638 8.47 7.481 7.247 3.946 0.741935483870968 8.021 8.014 7.831 7.127 6.885 3.864 0.774193548387097 7.644 7.638 7.515 6.963 6.299 3.724 0.806451612903226 6.718 6.705 6.502 6.185 6.034 3.546 0.838709677419355 6.031 6.026 5.945 5.53 5.221 2.958 0.870967741935484 5.752 5.748 5.657 5.414 5.077 2.957 0.903225806451613 5.493 5.489 5.401 4.896 4.57 2.735

### 187 0.935483870967742 5.256 5.252 5.17 4.866 4.535 2.706 0.967741935483871 4.726 4.722 4.643 4.222 4.041 2.648

0.1 33.982 33.962 33.407 30.143 26.944 11.0014 Average of yearly averages: 6.06586666666667
Inputs generated by pe4.pl - 8-August-2003

Data used for this run: Output File: econut1 Metfile: w13737.dvf PRZM scenario: NCpeanutC.txt EXAMS environment file: pond298.exv Chemical Name: pcnb Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42E-5 atm-m^3/mol Vapor Pressure vapr 1.13E-4 torr Solubility sol 4.4 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 2248 days Halfife Anaerobic Aquatic Metabolism kbacs 2004 days Halfife Aerobic Soil Metabolism asm 1124 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 1 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 11.2 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 15-04 dd/mm or dd/mmm or dd-mm or dd-mmm Interval 1 interval days Set to 0 or delete line for single app. Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Pond Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)

### 188 4. Potatoes (Standard Idaho Potatoes Scenario)
surface water numbers

stored as ecopot1.out Chemical: pcnb PRZM environment: IDpotatoC.txt modified Satday, 12 October 2002 at 17:00:44 EXAMS environment: pond298.exv modified Thuday, 29 August 2002 at 16:33:30 Metfile: w24156.dvf modified Wedday, 3 July 2002 at 09:04:38 Water segment concentrations (ppb)
Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 13.99 11.87 6.764 2.997 2.2 1.086 1962 14.07 12.16 7.136 3.219 2.393 0.9834 1963 15.07 13.33 9.007 4.814 3.573 1.345 1964 14.23 12.02 6.631 3.52 2.73 1.016 1965 14.16 12.4 7.555 4.003 3.227 1.655 1966 14.18 12.19 7.005 3.065 2.112 0.6513 1967 14.29 12.3 7.229 4.411 3.129 0.8806 1968 14.02 12.81 7.993 3.795 2.673 0.9341 1969 14.04 12.21 7.293 4.172 2.915 0.983 1970 33.42 29.32 18.4 9.407 6.59 1.951 1971 14.28 12.44 7.536 3.512 2.548 1.466 1972 14.11 12.3 7.378 3.342 2.523 1.344 1973 14.03 12.02 6.836 3.114 2.497 0.9645 1974 23.72 20.09 11.12 4.889 3.38 1.195 1975 14.28 12.16 6.746 2.898 2.016 0.9386 1976 14.45 12.47 7.207 3.402 2.42 1.338 1977 14.89 12.87 7.542 3.479 2.399 0.8099 1978 15.73 13.51 7.77 3.521 2.425 0.8311 1979 14.13 12.35 7.486 3.473 2.45 1.205 1980 14.16 12.35 8.981 5.173 3.592 2.075 1981 22.73 19.71 11.98 5.32 3.672 1.318 1982 14.18 12.3 7.32 3.385 2.458 1.397 1983 14.06 12.17 7.157 3.792 2.656 1.278 1984 14.12 11.65 6.075 2.844 2.582 1.232 1985 14.17 12.21 7.08 3.374 2.767 0.877 1986 14.09 12.12 6.966 3.09 2.123 0.9869 1987 14.17 12.24 7.137 3.185 2.393 0.662 1988 14.01 12 6.815 2.957 2.021 0.822 1989 14.12 12.15 7.066 3.216 2.228 1.165 1990 14.11 12.23 7.741 3.712 2.565 1.036

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 33.42 29.32 18.4 9.407 6.59 2.075 0.0645161290322581 23.72 20.09 11.98 5.32 3.672 1.951 0.0967741935483871 22.73 19.71 11.12 5.173 3.592 1.655 0.129032258064516 15.73 13.51 9.007 4.889 3.573 1.466 0.161290322580645 15.07 13.33 8.981 4.814 3.38 1.397 0.193548387096774 14.89 12.87 7.993 4.411 3.227 1.345 0.225806451612903 14.45 12.81 7.77 4.172 3.129 1.344 0.258064516129032 14.29 12.47 7.741 4.003 2.915 1.338 0.290322580645161 14.28 12.44 7.555 3.795 2.767 1.318 0.32258064516129 14.28 12.4 7.542 3.792 2.73 1.278 0.354838709677419 14.23 12.35 7.536 3.712 2.673 1.232 0.387096774193548 14.18 12.35 7.486 3.521 2.656 1.205 0.419354838709677 14.18 12.3 7.378 3.52 2.582 1.195 0.451612903225806 14.17 12.3 7.32 3.512 2.565 1.165 0.483870967741936 14.17 12.3 7.293 3.479 2.548 1.086 0.516129032258065 14.16 12.24 7.229 3.473 2.523 1.036 0.548387096774194 14.16 12.23 7.207 3.402 2.497 1.016 0.580645161290323 14.13 12.21 7.157 3.385 2.458 0.9869 0.612903225806452 14.12 12.21 7.137 3.374 2.45 0.9834 0.645161290322581 14.12 12.19 7.136 3.342 2.425 0.983 0.67741935483871 14.11 12.17 7.08 3.219 2.42 0.9645 0.709677419354839 14.11 12.16 7.066 3.216 2.399 0.9386 0.741935483870968 14.09 12.16 7.005 3.185 2.393 0.9341 0.774193548387097 14.07 12.15 6.966 3.114 2.393 0.8806 0.806451612903226 14.06 12.12 6.836 3.09 2.228 0.877 0.838709677419355 14.04 12.02 6.815 3.065 2.2 0.8311

### 189 0.870967741935484 14.03 12.02 6.764 2.997 2.123 0.822 0.903225806451613 14.02 12 6.746 2.957 2.112 0.8099 0.935483870967742 14.01 11.87 6.631 2.898 2.021 0.662 0.967741935483871 13.99 11.65 6.075 2.844 2.016 0.6513

0.1 22.03 19.09 10.9087 5.1446 3.5901 1.6361 Average of yearly averages: 1.14754666666667
Inputs generated by pe4.pl - 8-August-2003

Data used for this run: Output File: ecopot1 Metfile: w24156.dvf PRZM scenario: IDpotatoC.txt EXAMS environment file: pond298.exv Chemical Name: pcnb Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42E-5 atm-m^3/mol Vapor Pressure vapr 1.13E-4 torr Solubility sol 4.4 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 2248 days Halfife Anaerobic Aquatic Metabolism kbacs 2004 days Halfife Aerobic Soil Metabolism asm 1124 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 4 integer See PRZM manual Incorporation Depth: DEPI 10 cm Application Rate: TAPP 28 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 20-05 dd/mm or dd/mmm or dd-mm or dd-mmm Interval 1 interval days Set to 0 or delete line for single app. Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Pond Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)

### 190 benthic numbers

stored as ecopot1ben.out Chemical: pcnb PRZM environment: IDpotatoC.txt modified Satday, 12 October 2002 at 17:00:44 EXAMS environment: pond298.exv modified Thuday, 29 August 2002 at 16:33:30 Metfile: w24156.dvf modified Wedday, 3 July 2002 at 09:04:38 Benthic segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 2.011 2.009 1.979 1.811 1.715 0.8641 1962 2.239 2.237 2.199 1.979 1.8 1.145 1963 3.295 3.293 3.246 2.954 2.664 1.358 1964 2.381 2.38 2.338 2.147 1.952 0.9539 1965 2.789 2.787 2.727 2.68 2.568 1.749 1966 1.935 1.933 1.898 1.696 1.505 0.7166 1967 2.517 2.515 2.479 2.257 2.061 0.8571 1968 2.31 2.308 2.27 2.044 1.854 0.9368 1969 2.71 2.708 2.665 2.387 2.157 1.007 1970 7.237 7.232 7.121 6.492 5.862 2.437 1971 2.398 2.396 2.359 2.138 1.919 1.332 1972 2.467 2.465 2.424 2.18 1.99 1.538 1973 1.953 1.951 1.911 1.754 1.672 0.9978 1974 4.249 4.246 4.168 3.722 3.306 1.476 1975 1.928 1.926 1.887 1.67 1.48 0.884 1976 2.303 2.301 2.257 2.01 1.787 1.27 1977 2.301 2.299 2.257 2.029 1.809 1.011 1978 2.028 2.026 1.992 1.792 1.599 0.684 1979 2.594 2.593 2.552 2.31 2.08 1.307 1980 3.057 3.055 3.015 2.746 2.47 1.845 1981 4.348 4.344 4.263 3.805 3.381 1.685 1982 2.489 2.487 2.448 2.216 2.005 1.378 1983 2.516 2.515 2.473 2.225 2.029 1.244 1984 2.299 2.297 2.254 2.056 2.022 1.439 1985 2.283 2.281 2.247 2.094 1.897 0.8962 1986 2.231 2.229 2.19 1.962 1.745 0.9827 1987 1.858 1.856 1.825 1.654 1.534 0.6651 1988 1.785 1.784 1.751 1.561 1.384 0.6688 1989 2.498 2.496 2.455 2.212 1.976 1.267 1990 2.669 2.667 2.62 2.363 2.113 1.081

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 7.237 7.232 7.121 6.492 5.862 2.437 0.0645161290322581 4.348 4.344 4.263 3.805 3.381 1.845 0.0967741935483871 4.249 4.246 4.168 3.722 3.306 1.749 0.129032258064516 3.295 3.293 3.246 2.954 2.664 1.685 0.161290322580645 3.057 3.055 3.015 2.746 2.568 1.538 0.193548387096774 2.789 2.787 2.727 2.68 2.47 1.476 0.225806451612903 2.71 2.708 2.665 2.387 2.157 1.439 0.258064516129032 2.669 2.667 2.62 2.363 2.113 1.378 0.290322580645161 2.594 2.593 2.552 2.31 2.08 1.358 0.32258064516129 2.517 2.515 2.479 2.257 2.061 1.332 0.354838709677419 2.516 2.515 2.473 2.225 2.029 1.307 0.387096774193548 2.498 2.496 2.455 2.216 2.022 1.27 0.419354838709677 2.489 2.487 2.448 2.212 2.005 1.267 0.451612903225806 2.467 2.465 2.424 2.18 1.99 1.244 0.483870967741936 2.398 2.396 2.359 2.147 1.976 1.145 0.516129032258065 2.381 2.38 2.338 2.138 1.952 1.081 0.548387096774194 2.31 2.308 2.27 2.094 1.919 1.011 0.580645161290323 2.303 2.301 2.257 2.056 1.897 1.007 0.612903225806452 2.301 2.299 2.257 2.044 1.854 0.9978 0.645161290322581 2.299 2.297 2.254 2.029 1.809 0.9827 0.67741935483871 2.283 2.281 2.247 2.01 1.8 0.9539 0.709677419354839 2.239 2.237 2.199 1.979 1.787 0.9368 0.741935483870968 2.231 2.229 2.19 1.962 1.745 0.8962 0.774193548387097 2.028 2.026 1.992 1.811 1.715 0.884 0.806451612903226 2.011 2.009 1.979 1.792 1.672 0.8641 0.838709677419355 1.953 1.951 1.911 1.754 1.599 0.8571 0.870967741935484 1.935 1.933 1.898 1.696 1.534 0.7166 0.903225806451613 1.928 1.926 1.887 1.67 1.505 0.684

### 191 0.935483870967742 1.858 1.856 1.825 1.654 1.48 0.6688 0.967741935483871 1.785 1.784 1.751 1.561 1.384 0.6651

0.1 4.1536 4.1507 4.0758 3.6452 3.2418 1.7426 Average of yearly averages: 1.18920333333333
Inputs generated by pe4.pl - 8-August-2003

Data used for this run: Output File: ecopot1 Metfile: w24156.dvf PRZM scenario: IDpotatoC.txt EXAMS environment file: pond298.exv Chemical Name: pcnb Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42E-5 atm-m^3/mol Vapor Pressure vapr 1.13E-4 torr Solubility sol 4.4 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 2248 days Halfife Anaerobic Aquatic Metabolism kbacs 2004 days Halfife Aerobic Soil Metabolism asm 1124 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 4 integer See PRZM manual Incorporation Depth: DEPI 10 cm Application Rate: TAPP 28 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 20-05 dd/mm or dd/mmm or dd-mm or dd-mmm Interval 1 interval days Set to 0 or delete line for single app. Record 17: FILTRA IPSCND 1 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Pond Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)

### 192 5. Turfgrass (Standard Pennsylvania Turfgrass Scenario)
surface water numbers

stored as ecoturf1.out Chemical: pcnb PRZM environment: PAturfC.txt modified Satday, 12 October 2002 at 17:27:02 EXAMS environment: pond298.exv modified Thuday, 29 August 2002 at 16:33:30 Metfile: w14737.dvf modified Wedday, 3 July 2002 at 09:06:12 Water segment concentrations (ppb)
Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 99.61 98.38 82.58 45.62 30.41 7.499 1962 129 128 123 114 91.7 27.39 1963 68.47 67.54 64.13 31.76 21.25 10.38 1964 150 148 143 130 103 32.93 1965 76.14 75.63 73.42 59.71 50.34 15.66 1966 52.08 51.52 47.74 28.95 23.98 10.85 1967 105 93.29 73.57 60.9 50.71 19.07 1968 44.16 43.66 41.88 34.84 29.15 12.36 1969 166 164 155 62.16 41.54 18.09 1970 151 150 146 139 114 34.33 1971 115 113 105 58.58 47.04 17.44 1972 44.89 39.9 31.72 22.05 18.23 8.237 1973 133 118 100 42.85 28.62 10.34 1974 281 247 160 68.92 54.98 25.45 1975 70.65 70.36 69.44 52.06 37.66 12.1 1976 196 194 183 79.53 53.11 21.79 1977 168 167 161 152 122 39.82 1978 126 124 119 116 94.92 29.86 1979 56.43 55.96 54.24 49.55 40.42 12.76 1980 60.1 53.05 50.59 32.21 21.5 6.829 1981 57.02 50.28 45.04 38.45 28.54 9.959 1982 77.92 77.22 74.67 71.65 56.72 16.69 1983 259 256 238 105 70.22 20.82 1984 241 239 230 166 119 33.24 1985 327 287 187 122 81.69 22.03 1986 145 145 142 135 110 33.57 1987 31.94 31.71 30.95 29.67 24.23 8.468 1988 255 223 155 99.82 66.58 19.21 1989 121 108 70.51 42.88 33.99 11.8 1990 42.55 37.65 25.61 15.15 11.26 5.279

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 327 287 238 166 122 39.82 0.0645161290322581 281 256 230 152 119 34.33 0.0967741935483871 259 247 187 139 114 33.57 0.129032258064516 255 239 183 135 110 33.24 0.161290322580645 241 223 161 130 103 32.93 0.193548387096774 196 194 160 122 94.92 29.86 0.225806451612903 168 167 155 116 91.7 27.39 0.258064516129032 166 164 155 114 81.69 25.45 0.290322580645161 151 150 146 105 70.22 22.03 0.32258064516129 150 148 143 99.82 66.58 21.79 0.354838709677419 145 145 142 79.53 56.72 20.82 0.387096774193548 133 128 123 71.65 54.98 19.21 0.419354838709677 129 124 119 68.92 53.11 19.07 0.451612903225806 126 118 105 62.16 50.71 18.09 0.483870967741936 121 113 100 60.9 50.34 17.44 0.516129032258065 115 108 82.58 59.71 47.04 16.69 0.548387096774194 105 98.38 74.67 58.58 41.54 15.66 0.580645161290323 99.61 93.29 73.57 52.06 40.42 12.76 0.612903225806452 77.92 77.22 73.42 49.55 37.66 12.36 0.645161290322581 76.14 75.63 70.51 45.62 33.99 12.1 0.67741935483871 70.65 70.36 69.44 42.88 30.41 11.8 0.709677419354839 68.47 67.54 64.13 42.85 29.15 10.85 0.741935483870968 60.1 55.96 54.24 38.45 28.62 10.38 0.774193548387097 57.02 53.05 50.59 34.84 28.54 10.34 0.806451612903226 56.43 51.52 47.74 32.21 24.23 9.959

### 193 0.838709677419355 52.08 50.28 45.04 31.76 23.98 8.468 0.870967741935484 44.89 43.66 41.88 29.67 21.5 8.237 0.903225806451613 44.16 39.9 31.72 28.95 21.25 7.499 0.935483870967742 42.55 37.65 30.95 22.05 18.23 6.829 0.967741935483871 31.94 31.71 25.61 15.15 11.26 5.279

0.1 258.6 246.2 186.6 138.6 113.6 33.537 Average of yearly averages: 18.4750333333333
Inputs generated by pe4.pl - 8-August-2003

Data used for this run: Output File: ecoturf1 Metfile: w14737.dvf PRZM scenario: PAturfC.txt EXAMS environment file: pond298.exv Chemical Name: pcnb Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42E-5 atm-m^3/mol Vapor Pressure vapr 1.13E-4 torr Solubility sol 4.4 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 2248 days Halfife Anaerobic Aquatic Metabolism kbacs 2004 days Halfife Aerobic Soil Metabolism asm 1124 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 1 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 36.59 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 15-11 dd/mm or dd/mmm or dd-mm or dd-mmm Interval 1 interval 21 days Set to 0 or delete line for single app. Record 17: FILTRA IPSCND 3 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Pond Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)

### 194 benthic numbers stored as ecoturf1ben.out Chemical: pcnb PRZM environment: PAturfC.txt modified Satday, 12 October 2002 at 17:27:02 EXAMS environment: pond298.exv modified Thuday, 29 August 2002 at 16:33:30 Metfile: w14737.dvf modified Wedday, 3 July 2002 at 09:06:12 Benthic segment concentrations (ppb)

Year Peak 96 hr 21 Day 60 Day 90 Day Yearly 1961 29.65 28.75 20.69 9.42 6.28 1.549 1962 78.19 78.14 77.02 72.14 67.41 30.77 1963 21.43 20.88 17.38 16.68 15.93 8.308 1964 83.05 83 81.85 76.22 70.81 32.8 1965 44.85 44.83 44.2 41 38.11 18.03 1966 21.59 21.57 21.22 19.23 17.39 8.905 1967 43.79 43.77 43.24 40.32 37.38 18.05 1968 29.8 29.79 29.4 27.81 26.56 13.12 1969 43.13 41.65 27.85 26.43 25 12.71 1970 99.71 99.65 98.28 91.86 86.03 39.8 1971 42.83 42.8 42.12 38.08 34.27 16.7 1972 20.26 20.25 20.01 19.3 18.81 9.141 1973 29.45 28.65 19.61 13.36 13.04 6.893 1974 51.8 51.76 51.09 48.4 45.7 22.44 1975 53.54 53.51 52.82 50.06 46.53 18.99 1976 54.59 52.94 36.86 27.16 24.37 12.44 1977 111 110 109 102 96.33 44.05 1978 80.06 80.02 79 74.31 69.62 32.37 1979 36.38 36.36 35.86 33.6 31.39 14.74 1980 20.5 20.12 16.4 7.914 6.364 4.091 1981 31.12 31.1 30.78 29.05 27.3 12.06 1982 45.07 45.04 44.37 41.03 37.84 17.1 1983 70.56 68.08 44.54 19.7 13.41 7.86 1984 130 130 128 119 110 45.35 1985 72.76 71.94 63.97 36.49 24.53 9.427 1986 109 109 107 102 96.7 44.22 1987 23.97 23.95 23.69 22.71 21.69 10.21 1988 61.25 60.39 51.96 26.99 18.25 8.518 1989 65.84 65.8 64.91 58.66 53.45 21.8 1990 13.41 13.41 13.22 12.11 11.51 5.451

Sorted results Prob. Peak 96 hr 21 Day 60 Day 90 Day Yearly 0.032258064516129 130 130 128 119 110 45.35 0.0645161290322581 111 110 109 102 96.7 44.22 0.0967741935483871 109 109 107 102 96.33 44.05 0.129032258064516 99.71 99.65 98.28 91.86 86.03 39.8 0.161290322580645 83.05 83 81.85 76.22 70.81 32.8 0.193548387096774 80.06 80.02 79 74.31 69.62 32.37 0.225806451612903 78.19 78.14 77.02 72.14 67.41 30.77 0.258064516129032 72.76 71.94 64.91 58.66 53.45 22.44 0.290322580645161 70.56 68.08 63.97 50.06 46.53 21.8 0.32258064516129 65.84 65.8 52.82 48.4 45.7 18.99 0.354838709677419 61.25 60.39 51.96 41.03 38.11 18.05 0.387096774193548 54.59 53.51 51.09 41 37.84 18.03 0.419354838709677 53.54 52.94 44.54 40.32 37.38 17.1 0.451612903225806 51.8 51.76 44.37 38.08 34.27 16.7 0.483870967741936 45.07 45.04 44.2 36.49 31.39 14.74 0.516129032258065 44.85 44.83 43.24 33.6 27.3 13.12 0.548387096774194 43.79 43.77 42.12 29.05 26.56 12.71 0.580645161290323 43.13 42.8 36.86 27.81 25 12.44 0.612903225806452 42.83 41.65 35.86 27.16 24.53 12.06 0.645161290322581 36.38 36.36 30.78 26.99 24.37 10.21 0.67741935483871 31.12 31.1 29.4 26.43 21.69 9.427 0.709677419354839 29.8 29.79 27.85 22.71 18.81 9.141 0.741935483870968 29.65 28.75 23.69 19.7 18.25 8.905 0.774193548387097 29.45 28.65 21.22 19.3 17.39 8.518 0.806451612903226 23.97 23.95 20.69 19.23 15.93 8.308 0.838709677419355 21.59 21.57 20.01 16.68 13.41 7.86 0.870967741935484 21.43 20.88 19.61 13.36 13.04 6.893

### 195 0.903225806451613 20.5 20.25 17.38 12.11 11.51 5.451 0.935483870967742 20.26 20.12 16.4 9.42 6.364 4.091 0.967741935483871 13.41 13.41 13.22 7.914 6.28 1.549 0.1 108.071 108.065 106.128 100.986 95.3 43.625 Average of yearly averages: 18.2631
Inputs generated by pe4.pl - 8-August-2003

Data used for this run: Output File: ecoturf1 Metfile: w14737.dvf PRZM scenario: PAturfC.txt EXAMS environment file: pond298.exv Chemical Name: pcnb Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42E-5 atm-m^3/mol Vapor Pressure vapr 1.13E-4 torr Solubility sol 4.4 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 2248 days Halfife Anaerobic Aquatic Metabolism kbacs 2004 days Halfife Aerobic Soil Metabolism asm 1124 days Halfife Hydrolysis: pH 7 0 days Half-life Method: CAM 1 integer See PRZM manual Incorporation Depth: DEPI 0 cm Application Rate: TAPP 36.59 kg/ha Application Efficiency: APPEFF 0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 15-11 dd/mm or dd/mmm or dd-mm or dd-mmm Interval 1 interval 21 days Set to 0 or delete line for single app. Record 17: FILTRA IPSCND 3 UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Pond Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)

### 196 

## D T M PV V BA r

A B 

## = + − 

## 10 3 1 75

13 13 2 .

/ / 

## ( ) (3) APPENDIX D6 TIER II SURFACE WATER MODELING FOR TURF WITH VOLATILIZATION ACCOUNTED FOR

Additional PRZM/and EXAMS simula tions were conducted using a provisional version of PRZM that has newer volatilization routines. This PRZM ve rsion, PRZM9 (dated November 10, 2004), is currently being used temporarily by EFED only for scenarios with irrigation. Key elements in the volatilization algorithms or routines in the current standard version (3.12 beta) of PRZM were found to not work correctly. The new version has had corrections to the routines th at handle volatilization; however, not all of these have been adequately QA/QC’ed at the time of this assessment . In general, these new routines are expected to be in the new standard version of PRZM used by the Agency for risk assessments. Because the new version has not yet been approved for standard use by EFED, the results from the modeling runs are incorporated into this risk assessment for comparison purposes only, and ca nnot (at this time) be used to replace the values which were determined using version 3.12 beta.
For this assessment, volatilization for PCNB was si mulated without simulating temperature correction in PRZM. Instead the Henry’s Law Constant was adjust ed to reflect the mean temperature at the time of application. This temperature was 6.2° C and is th e mean monthly temperature for November in Allentown, PA, which is the location for the weather data used in the standard Pennsylvania turf scenario.
The input parameters used reflect the volatilization of PCNB in PRZM are in Table D6-1. The methods for estimating these parameters are described below.

Table D6-1

. Parameters used to simulate PCNB without temperature simulation. Parameter Value Source Quality Diffusion Coefficient in Air (DAIR) 3849.4 cm 2 d -1 estimated (see text) poor Henry’s Law Constant (HENRYK) 3.77 x 10 -4 estimated (see text) poor Enthalpy of Vaporization (ENPY) 6.14 kcal mol estimated (see text) poor

Diffusion in Air
For use in modeling, the coefficient for diffusi on in air has usually been estimated by EFED by considering the molecular weight of the compound. As a first approximation, diffusion in air is proportional to the square root of the molecular weight. A be tter estimate was made here by also considering the molecular volume of PCNB. The specific method cho sen was developed by Fuller, Schettler and Giddings (1996) as described in Lyman, Reehl and Rosenblatt (1990). This equation is most accurate for non-polar gases at low to moderate temperatures, which describes the conditions being considered here. The relationship describes the diffusion of one gas into another and consid ers the properties of both. However, the air can be considered as a single gas with defined (a nd constant) properties. The equation is

where D BAis the diffusion coefficient of gas B into gas A, T is the temperature in Kelvin, M r is the reduced mass, P is the pressure, and V Aand V B are the molecular volumes of gases A and B respectively. The reduced mass is:

### 197 

## M M M M M r A B

A B 

## = + (4)

Table D6-2. Estimation of the Molar Volume of PCNB using Atomic and Structural Diffusion Coefficients using the method of Fuller, Schettler, and Giddings (1966) as presented in Lyman, Reehl and Rosenblatt, 1990.


### Atom Number ) 

### V E ) 

### V
C 6 16.5 99.0
O 2 5.48 10.96 N 1 (5.69) 5.69 Cl 5 (19.5) 97.5
aromatic 1 -20.2 -20.2
total 192.95 Values in parentheses are based on fewer data points and thus have greater uncertainty. where M Aand M B are the molecular masses of gases A and B respectively. For diffusion into air, the effective molecular mass of air (M A ) is 28.97 g mol -1 and the effective molar volume is 20.1 cm 3 mol -1 . The temperature is 298 K (25° C) and the pressure P is 1 atm. The molecular weight of PCNB is 295.3 g mol -1 leaving only the molar volume of PCNB to fill all the parameters in Equation 2. The mo lar volume of PCNB was estimated using a qualitative structure activity relationship (QSAR), where volume increments are accumulated for each atom, and adjustment is made for the presence of aromatic rings . The calculations for estimating the molar volume are in Table D6-2. The diffusion coefficient in air as estimate by Equation 1 is 4.45 x 10 -2 cm 2 sec -1 or 3849 cm 2 d -1 , in the units used in PRZM.

Henry’s Law Constant
The value for the Henry’s Law Constant is the same as that used for EXAMS, 4.42 x 10 -5 atm m 3 mol -1 . However, it has been adjusted for temperature, and converted to the dimensionless (unitless) form of the Henry’s Law Constant, which is the form for input into PRZM. The temperature correction was made using the Clausius-Clapeyron equation (Dickerson, 1969), and is the same equation used internally by PRZM when the temperature is being simulated. This equation is



## K Ke H H H
R T T vap



## = − −            

1 1 1
1 ∆ 

### (3

where is the Henry’s Law constant at standard temperature and pressure, ) H vap is the enthalpy of vaporization at standard temperature and pressure, R is the gas law constant of 8.21 x 10 -5 atm m 3 mol -1 K -1 , T is the evaluation temperature 279.35 K (6.2° C), and T 1 is the temperature for KH1 of 298.15 K.
The dimensionless Henry’s Constant is calculated by dividing by the gas law constant, R, and standard temperature, which the temperature at sta ndard test conditions for estimating the Henry’s Law Constant. The dimensionless Henry’s Law Constant is 3.77 x 10 -4

. Enthalpy of Vaporization
PRZM uses the enthalpy of vaporization, ) H vap , to adjust the Henry’s Law constant for temperature and it is a required input parameter even when temper ature adjustment is not activated. The enthalpy of vaporization in the amount of energy required to convert a substance from a solid or liquid, into a gas. The temperature adjustment is made using the Clausi us-Clapeyron equation (Dic kerson, 1969) which assumes

### 198 

### ∆ H RK T P PT T T T vap b kl b c cb c

b c , 

### ln( ) [ ( ) ] ( ) = −

− 1 1 1 3 

# ∆ H RK T P PT T T T vap b kl b c cb c

b c , 

# ln( ) [ ( ) ] ( ) = −

− 1 1 1 3 

### (6) that ) H vap is a constant. In fact, the enthalpy of vapor ization is a function of temperature and is often tabulated at two different temperatures, standard te mperature and pressure (STP), that is 298.15 K and 1 atm, or at the boiling point at 1 atm. For the purposes of this assessment, the value at STP was used as this value is within the range of temperatures in the environm ent and should provide somewhat more accurate results.
The enthalpy of vaporization was estimated using a QSAR approach, the modified Klein method (Lyman, Reehl, and Rosenblatt, 1990; Fishtine, 1963; Klein, 1949). This method estimates the enthalpy of vaporization based on boiling point temperature T b , the critical temperature T c , and the critical pressure P c . The critical temperature and pressure are the combination of conditions where the solid, liquid, and gas phases for a substance all can coexist. The modified Klein method estimates the enthalpy of vaporization at the boiling, ) H vap, b , according to the equation:
(5)

where R is the gas law constant, 1.9872 cal K -1 mol -1 , and K kl is an empirical correction factor that has a value of 1.02 for Tb < 200 K, 1.04 for T b between 200 and 300 K and 1.045 for T b > 300. Since the boiling point temperature for PCNB is 601.5 K (328° C), K kl is 1.045. Note that this value has to be converted to standard temperature and pressure conditions before we use it in PRZM. Since we do not have measured values for T c and P c , these also need to be estimated.

P c was estimated using an approach proposed by Lydersen (1955) which is based on the molecular weight and a critical pressure increments approach based on the chemical structure. The equation for estimating P c is:


## P
c 

## = ( . 0 3 4

where M is the molecular weight and E) P c is the sum of the critical pressure increments as defined by Lydersen. The calculation of E) P c is provided in Table D6-3. The estimated critical pressure for PCNB by this method is 27.38 atm.

### 199 Table D6-3. Calculation of the sum of the critical pressure elements, E) P c , for estimating the critical pressure of PCNB by the Lydersen method (1955).

Element Number Value Total ring C with double bond 6 0.154 0.924

Cl 5 0.320 1.6

NO 2 1 (0.42) 0.42

E) P c 2.944 Values in parentheses are based on a smaller data set and are subject to greater error.

The critical temperature was estimated in two steps. First, the ratio of the boiling point to the critical temperature, T b /T c , or 2 , was estimated according to a method developed by Lydersen and described in Reid and Sherwood, (1966) as this value appears to rela tively constant for many organic compounds (Gambill, 1959) Secondly, the critical temperature was estimated using this value and the boiling point temperature, which is measured, at 328° C (601.15 K). The equation for estimating 2 is: 

## θ = +− 0567 2



## . () Σ∆ Σ∆ T T (8)

where E) T are the sum of temperature increments based on the structure of PCNB. The calculation of E) T is in Table D6-4 . The value of the sum of temperature for PCNB is 0.206 K. The value of 2 is then 0.730. Then by definition, 

## T T

c b



## = θ (9)

and T c is then 822 K. With values for P c , T c , and T b , we can now calculate ) H vap, b using equation 3, with a resulting value of 10640 cal mol -1

. Once we have a value for ) H vap, b , we need to calculate corresponding value at standard temperature and pressure.

### 200 Table D6-4. Calculation of the sum of the critical pressure elements, E) T, for estimating the ratio of boiling point and critical temperatures of P CNB by the Lydersen method (Reid and Sherwood, 1966).

Element Number Value Total ring C with double bond 6 0.011 0.066
Cl 5 0.017 0.085

NO 2 1 (0.055) 0.055

E) T 0.206 Values in parentheses are based on a smaller data set and are subject to greater error.

Results
EECs that considered volatilization were calculated for the Pennsylvania turf scenario. All parameters for the simulation were the same accept for the addition of the volatilization input parameters as noted above. Simulations were done for both the standard pond a nd index reservoir. PRZM9 and EXAMS were run outside the currently used PE4 shell as PE4 does not allow manual adjustment of the Henry’s Law Constant for temperature separate for EXAMS. Output was summa rized using the Table 20 post-processor, dated April 13, 1999 which was the standard post-processor used prio r to the adoption of PE4. Comparative results for the pond simulation are in Table D6-5 , and for the reservoir in Table D6-6. For the pond and the reservoir, the 1-in-10-year acute values decreased by 25% a nd 27%, respectively. The chronic values were more greatly affected, with the 1-in-10-year 90-day m ean EEC for the pond decreased by 36% while the overall mean in the reservoir was down by 37%. 

### The 1-in-10-year 21-day and 60-day EEC’s for the pond decreased by approximately 22% and 28%, respectiv ely. Chronic drinking water exposures for turf use are predicted to decrease by approximately34%, from 65.5 ppb to 43.4 ppb. However, because the solubility limit of 440 ppb is us ed for the EDWC (in lieu of the previous model output value of 586.4 ppb), the effective decrease from taking vol atilization into account is only 1.9% for acute exposure. One would expect full simulation of so il temperature would only modestly affect these values.



### Table D6-5

. 

### Comparison of PRZM9/EXAMS-generated aquatic EECs for use of PCNB on turf in Pennsylvania with and without consideration of volatilization from soil and turf. EECs are 1-in-10 year values. Acute 4-Day 21-Day 60-Day 90-Day
Volatilization off 258.6 : 

### g L -1 

### 246.2 : 

### g L -1 

### 186.8 : 

### g L -1 

### 138.6 : 

### g L -1 

### 113.6 : 

### g L -1



### Volatilization on 193.0 : 

### g L -1 

### 181.2 : 

### g L -1 

### 146.4 : 

### g L -1 

### 100.2 : 

### g L -1 

### 72.5 : 

### g L -1

### 201 

### Table D6-6. Comparison of PRZM9/EXAMS-generated EDWCs for use of PCNB on turf in Pennsylvania with and without consideration of volatilization from soil and turf. Acute and annual mean EDWCs are 1-in-10-year values. Acute Chronic (Annual Mean) Overall

Volatilization off 587.7 : 

### g L -1 

### 65.5 : 

### g L -1 

### 33.7 : 

### g L -1



### Volatilization on 431.9 : 

### g L -1 

### 43.4 : 

### g L -1 

### 21.2 : 

### g L -1



### Literature Citations
Dickerson, Richard E. 1969. Molecular Thermodynamics. Benjamin/Cummings, Reading, Massachusetts.
Fishtine, S. H., 1966. Reliable Heats of Vaporization, Part 1. Ind. Eng. Chem., 

### 55 (4) 20-28.
Fuller, E. N., P. D. Schettler, and J. C. Giddi ngs. 1966. A New Method for Prediction of Binary Gas Diffusion Coefficients. Ind. Eng. Chem. 

### 58 , 19-27.
Gambill, W. R. 1959. Predict Critical Temperature. Chem. Eng. (NY). 

### 66 :181-184.
Klein, V. A., 1949. Latent Heats of Vaporization. Chem. Eng. Prog. 

### 45 , 675.
Lydersen, A. L. 1955. Estimation of Critical Properties of Organic Compounds. College of Engineering, University of Wisconsin, E ngineering Experiment Station Report 3, Madison,Wisconsin.
Lyman, Warren J., Willam F. Reehl, and David H. Rosenblatt. 1990. Handbook of Chemical Property Estimation Methods. American Chemical Society, Washington, DC.
Reid, R. C., and T. K. Sherwood. 1966. The Properties of Gases and Liquids - Their Estimation and Correlation, 2 nd 

### Ed. McGraw Hill Book Co., New York.``

### 202 Provisional PRZM9/EXAMS Modeling With Volat ilization for Turf Applied Twice at 32.67 lb ai/A/application at a 21-Day Interval
1. PRZM Files Pertaining to EEC Va lues for the Ecological Exposure Assessment
Output File: PCNB0003 Metfile: w14737.dvf PRZM scenario: PAturfC.txt EXAMS environment file: pond298.exv Chemical Name: PCNB Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42e-5 atm-m^3/mol Vapor Pressure vapr 1.13e-4 torr Solubility sol 10 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 2248 days Halfife Anaerobic Aquatic Metabolism kbacs 2004 days Halfife Aerobic Soil Metabolism asm 1124 days Halfife Hydrolysis: pH 5 0 days Half-life Hydrolysis: pH 7 0 days Half-life Hydrolysis: pH 9 0 days Half-life Method: CAM 1 integer See PRZM manual Incorporation Depth: DEPI cm Application Rate: TAPP 36.59 kg/ha Application Efficiency: APPEFF0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 15-11 dd/mm or dd/mmm or dd-mm or dd-mmm Interval 1 interval 21 days Set to 0 or delete line for single app. Record 17: FILTRA IPSCND UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR Pond Flag for runoff calc. RUNOFF none none, monthly or total(average of entire run)



### WATER COLUMN DISSOLVED CONCENTRATION (PPB)

YEAR PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY

---- ---- ------- ------ ------ ------ ------ 1961 67.070 66.270 58.190 33.430 22.280 5.495 1962 78.080 77.300 74.760 69.940 56.420 17.810 1963 49.420 48.760 46.330 23.630 17.430 8.781 1964 69.640 68.890 66.500 61.120 49.710 17.120

### 203 1965 49.080 48.730 47.310 37.810 31.940 10.480 1966 34.360 33.920 32.280 18.870 12.990 6.730 1967 66.220 58.680 40.830 34.320 29.130 11.470 1968 36.050 35.640 34.810 21.630 17.290 8.509 1969 102.000 100.000 95.130 40.120 26.840 13.100 1970 88.900 88.010 84.730 82.270 67.140 21.310 1971 49.300 48.830 45.840 32.040 27.000 10.720 1972 38.560 34.260 27.290 16.570 12.170 6.195 1973 92.130 81.560 67.700 30.310 20.270 8.178 1974 194.000 170.000 110.000 45.610 36.420 17.370 1975 49.190 48.980 47.870 36.020 26.180 8.710 1976 120.000 119.000 112.000 50.330 33.680 11.910 1977 103.000 102.000 98.570 92.830 73.620 24.560 1978 76.710 75.890 72.890 71.340 58.490 19.300 1979 46.490 46.090 44.600 39.840 32.720 10.560 1980 41.380 40.850 38.930 24.280 16.230 5.351 1981 36.010 35.710 34.600 26.100 18.890 7.379 1982 48.830 48.290 46.830 45.360 36.170 11.280 1983 200.000 198.000 185.000 85.110 56.760 15.580 1984 186.000 184.000 177.000 128.000 91.960 26.040 1985 269.000 236.000 154.000 102.000 67.990 18.310 1986 110.000 110.000 108.000 106.000 86.020 26.360 1987 26.330 23.290 21.360 20.620 17.140 6.464 1988 189.000 166.000 116.000 76.380 50.950 14.330 1989 93.920 83.690 54.690 33.040 26.040 9.574 1990 30.490 26.990 17.620 10.410 6.981 3.462

SORTED FOR PLOTTING

------ --- --------
PROB PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY

---- ---- ------- ------ ------ ------ ------ 0.032 269.000 236.000 185.000 128.000 91.960 26.360 0.065 200.000 198.000 177.000 106.000 86.020 26.040 0.097 194.000 184.000 154.000 102.000 73.620 24.560 0.129 189.000 170.000 116.000 92.830 67.990 21.310 0.161 186.000 166.000 112.000 85.110 67.140 19.300 0.194 120.000 119.000 110.000 82.270 58.490 18.310 0.226 110.000 110.000 108.000 76.380 56.760 17.810 0.258 103.000 102.000 98.570 71.340 56.420 17.370 0.290 102.000 100.000 95.130 69.940 50.950 17.120 0.323 93.920 88.010 84.730 61.120 49.710 15.580 0.355 92.130 83.690 74.760 50.330 36.420 14.330

### 204 0.387 88.900 81.560 72.890 45.610 36.170 13.100 0.419 78.080 77.300 67.700 45.360 33.680 11.910 0.452 76.710 75.890 66.500 40.120 32.720 11.470 0.484 69.640 68.890 58.190 39.840 31.940 11.280 0.516 67.070 66.270 54.690 37.810 29.130 10.720 0.548 66.220 58.680 47.870 36.020 27.000 10.560 0.581 49.420 48.980 47.310 34.320 26.840 10.480 0.613 49.300 48.830 46.830 33.430 26.180 9.574 0.645 49.190 48.760 46.330 33.040 26.040 8.781 0.677 49.080 48.730 45.840 32.040 22.280 8.710 0.710 48.830 48.290 44.600 30.310 20.270 8.509 0.742 46.490 46.090 40.830 26.100 18.890 8.178 0.774 41.380 40.850 38.930 24.280 17.430 7.379 0.806 38.560 35.710 34.810 23.630 17.290 6.730 0.839 36.050 35.640 34.600 21.630 17.140 6.464 0.871 36.010 34.260 32.280 20.620 16.230 6.195 0.903 34.360 33.920 27.290 18.870 12.990 5.495 0.935 30.490 26.990 21.360 16.570 12.170 5.351 0.968 26.330 23.290 17.620 10.410 6.981 3.462

1/10 193.500 182.600 150.200 101.083 73.057 24.235

MEAN OF ANNUAL VALUES = 12.748

STANDARD DEVIATION OF ANNUAL VALUES = 6.341

UPPER 90% CONFIDENCE LIMIT ON MEAN = 14.467

2. PRZM Files Pertaining to EDWC Values for the Drinking Water Assessment
Output File: PCNB0005 Metfile: w14737.dvf PRZM scenario: PAturfC.txt EXAMS environment file: ir298.exv Chemical Name: PCNB Description Variable Name Value Units Comments Molecular weight mwt 295.3 g/mol Henry's Law Const. henry 4.42e-5 atm-m^3/mol Vapor Pressure vapr 1.13e-4 torr Solubility sol 10 mg/L Kd Kd 15.5 mg/L Koc Koc mg/L Photolysis half-life kdp 1.83 days Half-life Aerobic Aquatic Metabolism kbacw 3110 days Halfife Anaerobic Aquatic Metabolism kbacs 1460 days Halfife

### 205 Aerobic Soil Metabolism asm 1555 days Halfife Hydrolysis: pH 5 0 days Half-life Hydrolysis: pH 7 0 days Half-life Hydrolysis: pH 9 0 days Half-life Method: CAM 1 integer See PRZM manual Incorporation Depth: DEPI cm Application Rate: TAPP 36.59 kg/ha Application Efficiency: APPEFF0.99 fraction Spray Drift DRFT 0.01 fraction of application rate applied to pond Application Date Date 15-11 dd/mm or dd/mmm or dd-mm or dd-mmm Interval 1 interval 21 days Set to 0 or delete line for single app. Record 17: FILTRA IPSCND UPTKF Record 18: PLVKRT PLDKRT FEXTRC 0.5 Flag for Index Res. Run IR IR Flag for runoff calc. RUNOFF total none, mont hly or total(average of entire run)


### PCNB0005; index res.;volat on 12/22/2004
WATER COLUMN DISSOLVED CONCENTRATION (PPB)

YEAR PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY

---- ---- ------- ------ ------ ------ ------ 1961 121.000 119.000 100.000 56.350 37.560 9.263 1962 151.000 150.000 144.000 133.000 104.000 29.180 1963 77.660 76.760 73.260 34.160 23.050 9.371 1964 133.000 132.000 127.000 115.000 90.450 29.120 1965 101.000 101.000 97.000 74.160 61.150 17.430 1966 49.590 49.100 45.460 26.190 21.240 9.313 1967 129.000 112.000 70.700 49.340 40.650 16.270 1968 50.290 45.450 43.540 32.810 26.970 12.150 1969 204.000 201.000 192.000 73.840 49.320 19.950 1970 180.000 178.000 171.000 164.000 130.000 37.390 1971 96.570 84.220 78.540 44.760 36.270 14.690 1972 59.070 51.590 39.290 23.000 16.940 8.522 1973 188.000 164.000 135.000 54.630 36.510 13.310 1974 431.000 373.000 229.000 87.810 67.130 32.030 1975 89.570 88.940 86.590 62.440 44.060 12.990 1976 248.000 245.000 233.000 98.940 66.190 22.880 1977 215.000 213.000 205.000 190.000 148.000 46.000 1978 150.000 148.000 142.000 139.000 111.000 34.020 1979 96.470 95.540 91.910 80.170 64.200 18.140 1980 77.260 66.310 53.980 35.100 23.480 6.771

### 206 1981 49.650 49.190 47.410 35.200 24.910 8.212 1982 85.430 84.600 81.370 76.960 59.310 16.640 1983 436.000 431.000 404.000 179.000 119.000 31.470 1984 411.000 407.000 391.000 271.000 189.000 49.900 1985 617.000 534.000 333.000 205.000 137.000 35.820 1986 204.000 203.000 197.000 193.000 152.000 44.130 1987 41.410 38.590 37.460 35.290 28.790 9.344 1988 432.000 374.000 246.000 152.000 101.000 26.880 1989 176.000 153.000 93.120 50.080 37.720 11.940 1990 34.550 30.090 19.960 10.290 6.918 3.473

SORTED FOR PLOTTING

------ --- --------
PROB PEAK 96 HOUR 21 DAY 60 DAY 90 DAY YEARLY

---- ---- ------- ------ ------ ------ ------ 0.032 617.000 534.000 404.000 271.000 189.000 49.900 0.065 436.000 431.000 391.000 205.000 152.000 46.000 0.097 432.000 407.000 333.000 193.000 148.000 44.130 0.129 431.000 374.000 246.000 190.000 137.000 37.390 0.161 411.000 373.000 233.000 179.000 130.000 35.820 0.194 248.000 245.000 229.000 164.000 119.000 34.020 0.226 215.000 213.000 205.000 152.000 111.000 32.030 0.258 204.000 203.000 197.000 139.000 104.000 31.470 0.290 204.000 201.000 192.000 133.000 101.000 29.180 0.323 188.000 178.000 171.000 115.000 90.450 29.120 0.355 180.000 164.000 144.000 98.940 67.130 26.880 0.387 176.000 153.000 142.000 87.810 66.190 22.880 0.419 151.000 150.000 135.000 80.170 64.200 19.950 0.452 150.000 148.000 127.000 76.960 61.150 18.140 0.484 133.000 132.000 100.000 74.160 59.310 17.430 0.516 129.000 119.000 97.000 73.840 49.320 16.640 0.548 121.000 112.000 93.120 62.440 44.060 16.270 0.581 101.000 101.000 91.910 56.350 40.650 14.690 0.613 96.570 95.540 86.590 54.630 37.720 13.310 0.645 96.470 88.940 81.370 50.080 37.560 12.990 0.677 89.570 84.600 78.540 49.340 36.510 12.150 0.710 85.430 84.220 73.260 44.760 36.270 11.940 0.742 77.660 76.760 70.700 35.290 28.790 9.371 0.774 77.260 66.310 53.980 35.200 26.970 9.344 0.806 59.070 51.590 47.410 35.100 24.910 9.313 0.839 50.290 49.190 45.460 34.160 23.480 9.263 0.871 49.650 49.100 43.540 32.810 23.050 8.522

### 207 0.903 49.590 45.450 39.290 26.190 21.240 8.212 0.935 41.410 38.590 37.460 23.000 16.940 6.771 0.968 34.550 30.090 19.960 10.290 6.918 3.473

1/10 431.900 403.700 324.300 192.700 146.900 43.456

MEAN OF ANNUAL VALUES = 21.220

STANDARD DEVIATION OF ANNUAL VALUES = 12.885

UPPER 90% CONFIDENCE LIMIT ON MEAN = 24.713

### 208 APPENDIX D7. SCI-GROW MODELING OUTPUTS
1. Turf (two applications at 32.67 lb a.i./A/application)

SCIGROW VERSION 2.3 ENVIRONMENTAL FATE AND EFFECTS DIVISION OFFICE OF PESTICIDE PROGRAMS U.S. ENVIRONMENTAL PROTECTION AGENCY SCREENING MODEL FOR AQUATIC PESTICIDE EXPOSURE

SciGrow version 2.3 chemical:pcnb time is 10/16/2003 15:13:54

------------------------------------------------------------------------ Application Number of Total Use Koc Soil Aerobic rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

------------------------------------------------------------------------ 32.670 2.0 65.340 1.59E+03 750.5

------------------------------------------------------------------------ groundwater screening cond (ppb) = 9.38E+00 ************************************************************************ 2. Peanuts (two applications at 10.0 lb a.i./A/application)

SciGrow version 2.3 chemical:pcnb time is 10/20/2003 13:11:59

------------------------------------------------------------------------ Application Number of Total Use Koc Soil Aerobic rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

------------------------------------------------------------------------ 10.000 2.0 20.000 1.59E+03 750.5

------------------------------------------------------------------------ groundwater screening cond (ppb) = 2.87E+00 ************************************************************************ 3. Cole Crops (one application at 30.0 lb a.i./A/application)

SciGrow version 2.3 chemical:pcnb time is 10/20/2003 13:14:52

------------------------------------------------------------------------ Application Number of Total Use Koc Soil Aerobic rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

------------------------------------------------------------------------ 30.000 1.0 30.000 1.59E+03 750.5

------------------------------------------------------------------------ groundwater screening cond (ppb) = 4.31E+00 ************************************************************************

### 209 4. Potatoes (one application at 25.0 lb a.i./A/application)

SciGrow version 2.3 chemical:pcnb time is 10/20/2003 13:17:48

------------------------------------------------------------------------ Application Number of Total Use Koc Soil Aerobic rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

------------------------------------------------------------------------ 25.000 1.0 25.000 1.59E+03 750.5

------------------------------------------------------------------------ groundwater screening cond (ppb) = 3.59E+00 ************************************************************************
5. Bulb Crops (one application at 213.4 lb a.i./A/application)

SciGrow version 2.3 chemical:pcnb time is 10/20/2003 13:19:59

------------------------------------------------------------------------ Application Number of Total Use Koc Soil Aerobic rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

------------------------------------------------------------------------ 213.400 1.0 213.400 1.59E+03 750.5

------------------------------------------------------------------------ groundwater screening cond (ppb) = 3.06E+01 *************************************************************************

6. Beans – dry type (one applicat ion at 40.84 lb a.i./A/application)

SciGrow version 2.3 chemical:pcnb time is 10/31/2003 13:36:55

------------------------------------------------------------------------ Application Number of Total Use Koc Soil Aerobic rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days)

------------------------------------------------------------------------ 40.840 1.0 40.840 1.59E+03 750.5

------------------------------------------------------------------------ groundwater screening cond (ppb) = 5.86E+00 ************************************************************************

### 210 APPENDIX E. ECOLOGICAL EFFECTS ASSESSMENT
Toxicity to Terrestrial Animals
Acute and Subacute Toxicity to Birds
The acute oral toxicity of pentachloron itrobenzene to 26 week-old bobwhite quail ( Colinus virginianus ) was assessed over 14 days (MRID 406180 -01). The 14 day-acute oral LD 50 exceeded the highest dose tested (>2,250 mg a.i/kg bw; Table E1 ). There was no mortality during the study. No physiological or behavioral abnormalities were obser ved and body weights and food consumption remained unaltered. According to the US EPA classification, pentachloronitrobenzene is classified as practically nontoxic on an acute exposure basis. The study is classi fied as scientifically sound and is consistent with Guideline §71-1 testing requirements for avian oral studies using bobwhite quail.

Table E1. Summary of avian acute toxicity test on bobwhite quail ( Colinus virginianus ) exposed to pentachloronitrobenzene.

Species Study Type % active ingredien t LD 50 mg/kg bw MRID No. Author

Year Toxicity Category Fulfills Guideline Requiremen t
Bobwhite quail Colinus virginianus acute oral 98.0 >2250 406180-01 Grimes,

1988 Practically nontoxic Core

Two subacute dietary studies using the technical grade active ingredient (TGAI) are required to establish the toxicity of PCNB to birds. The preferred test species are the bobwhite quail ( Colinus virginianus ) and the mallard duck ( Anas platyrhynchos ) ( Table E2 ). Four studies were submitted for review. In a 9-day quail study (MRID 406526-02), marked anorexia and le thargy were observed at the two highest test concentrations. A total of five birds died during the study (1 at the 27,000 ppm dose and 4 at the 54,000 ppm dose). Gross pathological examination of the five bi rds revealed no abnormalities. No vehicle was used to administer the doses in this test. In a 5-day study with quail (MRID 406180-03) the LC 50 exceeded the highest concentration (5,620 ppm) tested. Anorexia and significant low weight gain were observed in the 5,620 ppm treatment group. In a 9-day mallard duck study (MRID 406526-03), marked anorexia and lethargy were observed at the Gross pathological examination of the seven birds that died during testing revealed abnormalities in four of the birds; three had gas-filled intestines and the fourth had what was characterized as “yolk” in the abdominal cavity. No vehicle was used to administer the doses in this test. The dietary LC 50 value was reported as greater than the highest concentration (54,000 ppm) tested. In a 5-day study with mallard ducks (MRID 406180-02) the LC 50 again exceeded the highest concentration ( 5620 ppm) tested. No mortalities were observed in this experiment; however, anorexia and significantly reduced weight gain were reported in the highest treatment group. Based on the results of these studies, PCNB is classified as practically non-toxic to birds on a subacute dietary exposure basis. All of the dietary studies are classi fied as core and are consistent with Guideline §71-2 subacute avian dietary testing requirements.

### 211 Table E2. Summary of subacute dietar y toxicity studies with mallard ducks ( Anas platyrhynchos ) and bobwhite quail ( Colinus virginianus ) for pentachloronitrobenzene.

Species Study Type % active ingredien t LC 50 mg/kg/da y MRID No. Author

Year Toxicity Category Fulfills Guideline Requiremen t
Bobwhite quail Colinus virginianus 9-day acute dietary 99.0 >54,000 406526-02 Fletcher,

1988 Practically nontoxic Core

Bobwhite quail Colinus virginianus 5-day acute dietary 98.0 >5620 406180-03 Grimes,

1988 Practically nontoxic Core

Mallard duck Anas platyrhynchos 5-day acute dietary 98.0 >5620 406180-02 Grimes,

1988 Practically nontoxic Core

Mallard duck Anas platyrhynchos 9-day acute dietary 99.0 >54,000 406526-03 Fletcher,

1988 Practically nontoxic Core

Chronic Toxicity to Birds
Six avian reproduction dietary studies were submitted for review ( Table E3 ). In a study with bobwhite quail (MRID 439803-01), the NOEC was determ ined to be 1000 ppm based upon a reduction in 14-day survivor weight and a reduction in the percenta ge of 14-day hatchling survivors; the LOEC was 2,500 ppm. This avian reproduction study is sci entifically sound and is consistent with Guideline §71-4 testing requirements for an avian reproduction study us ing bobwhite quail; the study is classified as core. In a study with mallard ducks (MRID 439033-01), there were no overt signs of toxicity or reductions in body weights or feed consumption at any of the test concentrations when compared to controls. For all concentrations tested, there were no statistically significant e ffects on any reproductive parameters. The NOEC was determined to be 5,500 ppm (the highest concentrati on tested) and no LOEC was determined. This study is scientifically sound and is classified as core.
Two additional studies, bobwhite quail (MRI D 413211-01) and mallard ducks (MRID 413212-01), were classified as supplemental. These studies are scientifically sound and document adverse effects on reproductive endpoints. The quail study detected signi ficant reductions in the number of 14-day survivors, the number of eggs set, the percentage of hatchlings of eggs set and the body weight of offspring at all treatment levels. There was a significant reduction in the number of eggs laid, the number of hatchlings, viable embryos and number of eggs set at the 11,000 and 22,000 ppm treatment concentrations. Additionally, the number of viable embryos and live 15- to 20-day embryos were decreased at a dietary concentration of 22,000 ppm. This study was classified as supplemental due to an unus ually high percentage of defective eggs in the control group (40.8%) and the lack of 14-day-old survivors/pen data. The unusually high percentage of cracked eggs in the control group confounds an analysis of the effects of PCNB on egg quality. The mallard duck study detected decreases in egg shell thickness and female body weight at all treatment

### 212 levels. The number of eggs laid, viable embryos, live 15- to 20-day embryos and hatchlings were reduced at the 11,000 and 22,000 ppm treatment levels. The number of (cracked) eggs were significantly increased and the number of eggs set were decreased at the 22,000 ppm treatment concentration. The NOECs in these studies were therefore less than the lowest concentration (<5,500 ppm) tested ( Table E3 ). This study was classified as supplemental due to the lack of 14-day-old survivors/pen data. These two studies, while providing useful information on the effects of PCNB on avian reproduction, do not comply with Guideline §71-4 testing requirements to establish a chronic NOEC.
Table E3. Summary of avian reproduction study with mallard ducks ( Anas platyrhynchos ) and bobwhite quail ( Colinus virginianus ) for pentachloronitrobenzene.

Species % active ingredie nt NOEC / LOEC mg/kg most sensitive endpoint MRID No. Author

Year Fulfills Guideline Requirement

Bobwhite quail Colinus virginianus 97.4 1000 / 2500 14-day survivor weight, 14-day survivors 43980301 Pederson, 1995 Core

Mallard duck Anas platyrhynchos 97.4 5500 / not determined no significant effects noted at any concentration 43903301 Pedersen, 1995 Core

Bobwhite quail Colinus virginianus 98.5 <5500 / not determined 14-day survivors, number of eggs set, body weight offspring 41321101 Pedersen, 1989 Supplemental

Mallard duck Anas platyrhynchos 98.5 <5500 / not determined Egg shell thickness, female body weight 413212-01 Pedersen, 1989 Supplemental

Bobwhite quail Colinus virginianus 99.4 600 / 1200 14-day survivors 413328-01 Beavers,

1989 Core

Mallard duck Anas platyrhynchos 99.4 600 / 1200 adult body weight 413328-02 Beavers,

1989 Core

### 213 Acute and Chronic Toxicity to Mammals
Wild mammal testing is required on a case-by-case basis, depending on the results of lower-tier laboratory mammalian studies, intended use pattern and pe rtinent environmental fate characteristics. In an acute oral toxicity study ( Table E4 , MRID 414431-01), rats exposed to PCNB developed toxic symptoms that included slight piloerection, diarrhea and slight to moderate constriction of pupils at the higher treatment concentrations; all animals were asymptomatic after three days. The acute oral LD 50 exceeded the maximum dose (>5,050 ppm) tested.
In a 2-generation reproduction study with rats (MRID 434693-01, 434693-02, 434693-03) reviewed by the Health Effects Division, the data evaluation record reports:
“there were no compound-related effects in parental body weight , food consumption or reproductive performance. In addition, there were no clinical signs of toxicity in the parental animals. In the P 1 generation, hepatocellular hypertrophy was observed at 1000 mg/kg in both sexes and thyroid follicular cell hypertrophy/hyperplasia was observed at 100 and 1000 mg/kg in males and at 1000 mg/kg in females. There were no changes observed in the reproductive organs. In the P 2 generation, the effects were the same except that the liver effects were only observed in high dose males. No treatment-related effects were observed in litter size, pup viability, pup body weight or pup macroscopic examinations. No microscopic examinations were conducted on pups.
The LOEL is 100 mg/kg/day in males and 1000 mg/kg/day in females based on increases in hepatocellular hypertrophy and th yroid follicular cell hypertrophy/hyperplasia. The NOEL is 10 mg/kg/day in males and 100 mg/kg/day in females.
The reproductive study in the rat is classified as acceptable and satisfies the guideline requirement for a 2-generati on reproductive study (OPPTS 870.3800, §83-4) in the rat.”

Table E4. Acute and chronic toxicity of pentachloronitrobenzene to the rat.
Species % a.i. Endpoint (mg/kg) MRID Author, year Study Classification

Rat (Acute) 95 LD 50 >5,050 414431-01 (acute) acceptable Rat (Chronic) LOAEL = 100 NOEL = 10 434693-01, 434693-02, 434693-03 (chronic) acceptable

Toxicity to Insects
A honey bee acute contact study using the TGAI was required for PCNB because its use may result in honey bee exposure. The contact LD 50 was greater than the highest (>100 μg/bee) dose tested (MRID

### 214 405061-02, Table E5 ). No sublethal effects were noted in any of the control or test animals throughout the duration of the study. The study is scientifically sound and is consistent w ith Guideline §1141-1 testing requirements; the study is classified as core.

Table E5. Summary of acute contact and oral 48-hr toxicity tests with the honey bee ( Apis mellifera ) for pentachloronitrobenzene.

Species % active ingredient LD 50 : g/bee MRID No. Author/Year Toxicity Category Fulfills Guideline Requirement Honey Bee 99.5 >100 (contact) 40506102 Hoxter, 1987 Practically nontoxic Core

Toxicity to Freshwater Aquatic Animals
Freshwater Fish, Acute
Results of toxicity tests with freshwater fish are tabulated in Table E6 . Since the LC 50 values for the species tested are in the range, PCNB is classified as highly toxic to freshwater fish on an acute exposure basis. In acute toxic ity testing with bluegill sunfish (MRID 408490-01 and 410608- 01), sublethal effects including loss of equilibrium, fi sh at the bottom of the test chamber, and quiescence were noted at exposure concentrations ranging from 0.043 to 0.35 mg a.i./L. Similar sublethal effects were also noted in rainbow trout at PCNB exposure con centrations ranging from 0.13 to 0.45 mg a.i./L (MRID 409927-01). Both the freshwater fish studies are consis tent with Guideline §72-1(a) and §72-1(c) testing requirements and are classified as core.

### 215 Table E6. Summary of freshwater fish acute toxicity in mg/L (ppm) for technical grade pentachloronitrobenzene

. Species % ai 96-hour LC 50 (mg/L) Toxicity Category MRID No. Author/Year Study Classificatio

n

Rainbow Trout (Onchorynchus mykiss) 99 0.32 Highly Toxic 409927-01 Swigert 1988 core

Rainbow Trout (Onchorynchus mykiss) 98.2 0.55 Highly Toxic 406180-05 Surprenant 1988 core

Bluegill Sunfish (Lepomis macrochirus) 99 0.21 Highly Toxic 408490-01 Swigert 1988 core

Bluegill Sunfish (Lepomis macrochirus) 98.2 0.10 Highly Toxic 406180-04 Surprenant 1988 core

Acute toxicity was determined for the formulated end-use product as well; 96-hr LC 50 values ranged from 0.24 to 1.66 mg/L (ppm), indicating that formulated PCNB can be classified as moderately to highly toxic to freshwater fish ( Table E7 ). In acute toxicity testing of fo rmulated product with bluegill sunfish (MRID 410608-01), sublethal effects including hemorrhaging, loss of equilibrium, fish at the bottom of the test chamber, and quiescence were noted at exposure concentrations ranging from 0.073 to 0.58 mg a.i./L. Sublethal effects in rainbow trout were similar to those observed in bluegill sunf ish and occurred at exposure concentrations ranging from 0.099 to 0.76 mg a.i./L (MRID 410608-02). All of the formulated product tests were consistent with guide line §71-2 testing requirements.

Table E7. Summary of freshwater fish acute toxi city in mg/L (ppm) for formulated products of pentachloronitrobenzene. Species % ai 96-hour LC 50 (mg

a.i./L) Toxicity Category MRID No. Author/Year Study Classificatio

n

Rainbow Trout (Onchorynchus mykiss) 26.6 1.66 Moderately toxic 406503-01 Surprenant 1988 core

Rainbow Trout (Onchorynchus mykiss) 24 0.31 Highly Toxic 410608-02 Bowman 1989 coreSpecies % ai 96-hour LC 50 (mg

a.i./L) Toxicity Category MRID No. Author/Year Study Classificatio

n



### 216 Bluegill Sunfish (Lepomis macrochirus) 26.6 0.75 Highly Toxic 406503-02 Surprenant 1988 core

Bluegill Sunfish (Lepomis macrochirus) 24 0.24 Highly Toxic 410608-01 Bowman 1989 core

Freshwater Fish, Chronic

Table E8. Summary of freshwater fish early life st age toxicity data in μg/L (ppb) under flow-through conditions for technical grade pentachloronitrobenzene. Species % ai NOAEC/LO AEC (ppb) Endpoints Affected MRID No. Author/Year Study Classificatio

n
Rainbow Trout (Onchorynchus mykiss) 99 13 / 32 Growth (length and

weight) 416634-01 Cohle and Herzig 1990 core

A freshwater fish life-cycle test using the TGAI was submitted for pentachloronitrobenzene (MRID 408840-01) using the preferred test species fathead minnow ( Pimephales promelas ) and is summarized in Table E9. Embryo hatchability and larval survival were not affected at any exposure levels. Larval growth was significantly reduced at the 54 ppb treatment level. The mean larval weight at the highest concentration was 20% less than that of the pooled cont rol larvae. This study was classified as due to the lack of raw data being provided.
Table E9. Summary of freshwater fish full life cycle toxicity data in μg/L (ppb) for technical grade pentachloronitrobenzene

### 217 Species % ai NOAEC / LOAEC

(ppb) Toxicity Category MRID No. Author/Year Study Classificati

on
Fathead Minnow (Pimephales promelas ) 98.2 27 / 54 Very Highly Toxic 40884001 Surprenant, 1988 Supplement al

Freshwater Invertebrates, Acute
A freshwater invertebrate acute toxicity test (A cc. no. 114167) was submitted using the preferred test species Daphnia magna and is summarized in Table E10 . The 48-hour LC 50 was 0.77 mg/L and the NOEC was 0.13 mg/L. All daphnids exhibited lethargy in th e two highest concentrations tested. Additionally, several daphnids were caught at the surface of test solu tion in the next two lower concentrations. PCNB is categorized as highly toxic to aquatic i nvertebrates on an acute exposure basis ( Table E10 ). The study is consistent with Guideline §72-2 testing requirements and is classified as core.
Table E10. Summary of freshwater invertebrate acute toxicity in : g/L (ppb) for technical grade pentachloronitrobenzene

. Species/Static or

Flow-through % ai 48-hour LC 50 (mg/L) Toxicity Category MRID No. Author/Year Study Classificatio

n
Water flea (Daphnia magna ) 99.08 0.77 NOEC = 0.13 Highly toxic 114167 (accession) Core

Freshwater Invertebrate, Chronic
Two freshwater aquatic invertebrate life-cycl e tests using the TGAI were submitted for pentachloronitrobenzene (MRID 408323-04 and 413213-01) using the preferred test species Daphnia magna and are summarized in Table E11 . The first study (MRID 408323-04) observed a NOAEC of 19 : g/L and LOAEC of 34 : g/L. Reproduction was significantly reduced at the higher treatment levels. Because the authors of this study did not submit the raw data for ev aluation, this study is classified as supplemental since the statistical analysis could not be verified. A sec ond 21-day toxicity study preformed with the water flea estimated a NOAEC and a LOAEC of 18 : g/L and 30 : g/L (ppb), respectively, based on affected reproduction. The number of young per adult per day decreased significantly with increasing concentration of pentachloronitrobenzene. A one hundred percent mort ality was observed at the highest treatment level of 23 : g/L. Guideline 72-4(b) for freshwater invertebrates is fulfilled (MRID 00150901).

### 218 Table E11. Summary of freshwater aquati c invertebrate life-cycle toxicity in : g/L (ppb)for technical grade pentachloronitrobenzene

. Species % ai 21-day NOAEC/ LOAEC

(ppm) Endpoints Affected MRID No. Author/Year Study Classification

Water flea (Daphnia magna) 98.2 0.019 /0.0 34 Reproduction 40832304, 41918803 Surprenant, 1988 Supplemental

Water flea (Daphnia magna) 99.0 0.018 /0.030 Reproduction 41321301 Burgess, 1989 Core

Toxicity to Estuarine and Marine Animals
Estuarine/Marine Fish, Acute
Three estuarine/marine fish acute toxicity tests were submitted for review using the preferred test species sheepshead minnow ( Cyprinodon variegatus ). Two of the studies, MRID 423369-01 and 408323-02, were classified as . For study MRID 423369-01, additi onal information pertaining to the sampling methodology needs to be submitted for c onsideration. For study MRID 408323-02, the NOEL (<1.2 mg a.i./l) reported is not a tr ue NOEL but an approximation. This statement points to a whole set of possible NOEL values where PCNB could go from being mode rately toxic to being very highly toxic to the test organism under the test conditions used . Study MRID 408829-03 determined the 96-hour LC 50 to be 7.9 mg/L (ppm) ( Table E12 ) so, PCNB is categorized as moderately toxic to estuarine/marine fish on an acute exposure basis. Complete loss of equilibrium, erra tic swimming behavior, leth argy, and swimming at the surface were all observed in this test This third study is scientifically sound and is consistent withGuideline §72-3(a) testing requirements.

### 219 Table E12. Summary of estuarine/marine fish acute toxicity for technical grade pentachloronitrobenzene.
Species/Static % ai 96-hour LC 50 mg/L Toxicity Category MRID No. Author/Year Study Classificati

on Sheepshead

Minnow (Cyprinodon variegatus ) 98.98 1.7 Moderately Toxic 423369-01 Bettencourt, 1992 Supplement al

Sheepshead

Minnow (Cyprinodon variegatus) 98.2 1.5 Moderately Toxic 408323-02 Surprenant, 1988 Supplement al

Sheepshead

Minnow (Cyprinodon

variegatus 97.7 7.9 Moderately Toxic 408829-03 Surprenant, 1988 Core

Estuarine and Marine Fish, Chronic

No data were available to assess the chronic t oxicity of PCNB to estuarine/marine fish.

Estuarine and Marine Invertebrates, Acute

As shown in Table E13 , the 96-hour mysid shrimp LC 50 for technical PCNB is 12 : g/L (ppb) (MRID 408323-01). Thus, this chemical is categorized as very highly toxic to estuarine/ marine crustaceans on an acute exposure basis. This chemical is also very highly toxic to molluscs (LC 50 range: 23 – 24 : g/L ppb; MRID 408323-03 and 408829-02). The studies are scientifically sound and are consistent with Guidelines §72-3(b) and §72-3(c) testing requireme nts. For study MRID 408323-03, samples were not filtered prior to chemical analysis, so the dissolved leve ls of PCNB to which the oysters were exposed in the test chambers are unknown and; hence, PCNB is likely to be more toxic than reported. For study MRID 408829-02, the registrant filed to provide the raw datafor shell thickness measurements making it impossible to verify the statistical results.

### 220 Table E13. Summary of estuarine/marine inverteb rate acute toxicity for pentachloronitrobenzene. Species % ai. 96-hour LC 50 mg/L Toxicity Category MRID No. Author/Year Study Classificat ion Mysid ( Mysidopsis bahia ) 98.2 0.012 Very Highly Toxic 40832301 Surprenant, 1988 Core

Mysid ( Mysidopsis bahia ) 97.9 0.023 Very Highly Toxic 40882901 Surprenant, 1988 Core

Eastern Oyster

( Crassostrea

virginica ) 98.2 0.024 Very Highly Toxic 40832303 Surprenant, 1988 Supplemen tal

Eastern Oyster

( Crassostrea

virginica ) 97.7 0.023 Very Highly Toxic 40882902 Surprenant, 1988 Supplemen tal

Estuarine and Marine Invertebrate, Chronic
There are no available chronic toxicity data for estuarine/marine invertebrates. The guideline 72-4(b) for estuarine/marine invertebrates is not fulfilled.

### 221 APPENDIX F. SPREADSHEET-BASED TERRESTRIAL EXPOSURE VALUES
A first-order decay assumption is used to determ ine the concentration at each day after initial application based on the concentration resulting from th e initial and additional applications. The decay is calculated from the first order rate equation:

C T = C i e - k T or in log-transformed form: ln (C T /C i) = - k T Where: C T = concentration at time T

C i

= concentration in parts per million (ppm) present initially (on day zero) on the surfaces. C i is calculated based on Kenaga and Fletcher bymultiplying the application rate, in pounds active ingredient per acre, by 240 for short grass, 110 fo r tall grass, and 135 for broad-leaf plants/insects and 15 for seeds. Additional applications are converted from pounds active ingredient per acre to parts per million (PPM) on the plant surface and the additional mass added to the mass of the chemical still present on the surfaces on the day of application.

k = degradation rate constant determined from studi es of hydrolysis, photolysis, microbial degradation, etc. Since degradation rate is generally reported in terms of half-life, the rate constant is calculated from the input half-life (k = ln 2/t 1⁄2 ) instead of being input directly. Choosing which process controls the degradation rate and which half-life to use in terrestrial exposure calculations is open for debate and should be done by a qualified scientist.

T = time, in days, since the start of the simulation. The initial application is on day 0. The simulation is set to run for 365 days.
The program calculates concentration on each type of su rface on a daily interval for one year. The maximum concentration during the year and the average con centration during the first 56 days are calculated.

### 222 Chemical Name: PCNB Use cabbage Formulation spray 

### Inputs
Application Rate 22.5 lbs a.i./acre Half-life 35 days Frequency of Application 0 days Maximum # Apps./Year 1
Outputs

Maximum 56 day Average Concentration Concentration (PPM) (PPM) Short Grass 5400.00 3322.19 Tall Grass 2475.00 1522.67 # days Broadleaf plants/sm Insects 3037.50 1868.73 Exceeded F ru it s / po d s /l g i nsec t s 337.50 207.64 on short grass (in first 56)
Avian Acute LC50 (ppm) 54000 2

Chronic NOAEC (ppm) 600 55

Acute RQ Chronic RQ (Max. res. mult. apps.) Short Grass 0.10 9.00 Tall Grass 0.05 4.13 Broadleaf plants/sm Insects 0.06 5.06 Fruits/pods/lg insects 0.01 0.56

Mammalian Acute LD50 (mg/kg bw) 5050
Reported Chronic endpoint 10 Enter endpoint units 1 Dose or Diet Rat Calculated Endpoint 200 mg/kg-diet based on standard FDA lab rat conversion

15 g mammal 35 g mammal 1000 g mammal Mammal Chronic Acute RQ Acute RQ Acute RQ RQ (mult. apps) (mult. apps) (mult. apps) Dietary based Short Grass 1.02 0.71 0.16 27.00 Tall Grass 0.47 0.32 0.07 12.38 Broadleaf plants/sm insects 0.57 0.40 0.09 15.19 Fruits/pods/lg insects 0.06 0.04 0.01 1.69 Seeds (granivore) 0.01 0.01 0.00 Chronic RQ dose based Chronic RQ dose based Chronic RQ dose based Short Grass 513.00 356.40 81.00 Tall Grass 235.13 163.35 37.13 Broadleaf plants/sm insects 288.56 200.48 45.56 Fruits/pods/lg insects 32.06 22.28 5.06 Seeds (granivore) 7.09 5.06 1.01 Terresterial Application Residues

0 1000 2000 3000 4000 5000 6000

0 4 8 12 16 20 2 4 2 8 32 36 40 44 48 52 DaysConcentration (PPM) Short Grass

Tall Grass

Broadleaf plants/sm Insects Fruits/pods/l

mg/kg-bw APPENDIX G. TERRESTRIAL EXPOSURE MODEL (ELL FATE Version 1.4a) OUTPUT
Cabbage Maximum Residues

### 223 Chemical Name: PCNB Use cabbage Formulation spray 

### Inputs
Application Rate 22.5 lbs a.i./acre Half-life 35 days Frequency of Application 0 days Maximum # Apps./Year 1
Outputs

Maximum 56 day Average Concentration Concentration (PPM) (PPM) Short Grass 1912.50 1176.61 Tall Grass 810.00 498.33 # days Broadleaf plants/sm Insects 1012.50 622.91 Exceeded F ru it s / po d s /l g i nsec t s 157.50 96.90 on short grass (in first 56)
Avian Acute LC50 (ppm) 54000 0

Chronic NOAEC (ppm) 600 55

Acute RQ Chronic RQ (Max. res. mult. apps.) Short Grass 0.04 3.19 Tall Grass 0.02 1.3 5 Broadleaf plants/sm Insects 0.02 1.69 Fruits/pods/lg insects 0.00 0.26

Mammalian Acute LD50 (mg/kg bw) 5050
Reported Chronic endpoint 10 Enter endpoint units 1 Dose or Diet Rat Calculated Endpoint 200 mg/kg-diet based on standard FDA lab rat conversion

15 g mammal 35 g mammal 1000 g mammal Mammal Chronic Acute RQ Acute RQ Acute RQ RQ (mult. apps) (mult. apps) (mult. apps) Dietary based Short Grass 0.3 6 0.2 5 0.0 6 9.56 Tall Grass 0.1 5 0.11 0.02 4.0 5 Broadleaf plants/sm insects 0.19 0.13 0.03 5.06 Fruits/pods/lg insects 0.03 0.02 0.00 0.79 Seeds (granivore) 0.01 0.00 0.00 Chronic RQ dose based Chronic RQ dose based Chronic RQ dose based Short Grass 181.69 126.23 28.69 Tall Grass 76.9 5 53.46 12.1 5 Broadleaf plants/sm insects 96.19 66.83 15.19 Fruits/pods/lg insects 14.96 10.40 2.3 6 Seeds (granivore) 3.31 2.3 6 0.47 Terresterial Application Residues

0 500 1000 1500 2000 2500

0 4 8 1 2 16 2 0 24 2 8 3 2 36 4 0 44 4 8 52 DaysConcentration (PPM) Short Grass

Tall Grass

Broadleaf plants/sm Insects Fruits/pods/l

mg/kg-bw Cabbage Mean Residues

### 224 Chemical Name: PCNB Use peanuts Formulation spray SLN (TX) 

### Inputs
Application Rate 10 lbs a.i./acre Half-life 35 days Frequency of Application 0 days Maximum # Apps./Year 1
Outputs

Maximum 56 day Average Concentration Concentration (PPM) (PPM) Short Grass 2400.00 1476.53 Tall Grass 1100.00 676.74 # days Broadleaf plants/sm Insects 1350.00 830.5 5 Exceeded F ru it s / po d s /l g i nsec t s 150.00 92.28 on short grass (in first 56)
Avian Acute LC50 (ppm) 54000 2

Chronic NOAEC (ppm) 600 55

Acute RQ Chronic RQ (Max. res. mult. apps.) Short Grass 0.04 4.00 Tall Grass 0.02 1.83 Broadleaf plants/sm Insects 0.03 2.2 5 Fruits/pods/lg insects 0.00 0.2 5

Mammalian Acute LD50 (mg/kg bw) 5050
Reported Chronic endpoint 10 Enter endpoint units 1 Dose or Diet Rat Calculated Endpoint 200 mg/kg-diet based on standard FDA lab rat conversion

15 g mammal 35 g mammal 1000 g mammal Mammal Chronic Acute RQ Acute RQ Acute RQ RQ (mult. apps) (mult. apps) (mult. apps) Dietary based Short Grass 0.4 5 0.31 0.07 12.00 Tall Grass 0.21 0.14 0.03 5.50 Broadleaf plants/sm insects 0.2 5 0.18 0.04 6.7 5 Fruits/pods/lg insects 0.03 0.02 0.00 0.7 5 Seeds (granivore) 0.01 0.00 0.00 Chronic RQ dose based Chronic RQ dose based Chronic RQ dose based Short Grass 228.00 158.40 36.00 Tall Grass 104.50 72.60 16.50 Broadleaf plants/sm insects 128.2 5 89.10 20.25 Fruits/pods/lg insects 14.2 5 9.90 2.2 5 Seeds (granivore) 3.1 5 2.2 5 0.4 5 Terresterial Application Residues

0 500 1000 1500 2000 2500 3000

0 4 8 12 1 6 20 24 2 8 32 36 4 0 44 48 5 2 DaysConcentration (PPM) Short Grass

Tall Grass

Broadleaf plants/sm Insects Fruits/pods/l

mg/kg-bw Peanuts SLN (TX) Maximum Residues

### 225 Chemical Name: PCNB Use peanuts Formulation spray 

### Inputs
Application Rate 10 lbs a.i./acre Half-life 35 days Frequency of Application 0 days Maximum # Apps./Year 1
Outputs

Maximum 56 day Average Concentration Concentration (PPM) (PPM) Short Grass 850.00 522.94 Tall Grass 360.00 221.48 # days Broadleaf plants/sm Insects 450.00 276.8 5 Exceeded F ru it s / po d s /l g i nsec t s 70.00 43.07 on short grass (in first 56)
Avian Acute LC50 (ppm) 54000 0

Chronic NOAEC (ppm) 600 18

Acute RQ Chronic RQ (Max. res. mult. apps.) Short Grass 0.02 1.42 Tall Grass 0.01 0.60 Broadleaf plants/sm Insects 0.01 0.7 5 Fruits/pods/lg insects 0.00 0.12

Mammalian Acute LD50 (mg/kg bw) 5050
Reported Chronic endpoint 10 Enter endpoint units 1 Dose or Diet Rat Calculated Endpoint 200 mg/kg-diet based on standard FDA lab rat conversion

15 g mammal 35 g mammal 1000 g mammal Mammal Chronic Acute RQ Acute RQ Acute RQ RQ (mult. apps) (mult. apps) (mult. apps) Dietary based Short Grass 0.1 6 0.11 0.03 4.2 5 Tall Grass 0.07 0.0 5 0.01 1.80 Broadleaf plants/sm insects 0.08 0.0 6 0.01 2.2 5 Fruits/pods/lg insects 0.01 0.01 0.00 0.3 5 Seeds (granivore) 0.00 0.00 0.00 Chronic RQ dose based Chronic RQ dose based Chronic RQ dose based Short Grass 80.7 5 56.10 12.7 5 Tall Grass 34.20 23.76 5.40 Broadleaf plants/sm insects 42.7 5 29.70 6.7 5 Fruits/pods/lg insects 6.6 5 4.62 1.0 5 Seeds (granivore) 1.47 1.0 5 0.21 Terresterial Application Residues

0 100 200 300 400 500 600 700 800 900

0 4 8 12 16 2 0 2 4 2 8 3 2 3 6 4 0 4 4 4 8 52 DaysConcentration (PPM) Short Grass

Tall Grass

Broadleaf plants/sm Insects Fruits/pods/l

mg/kg-bw Peanuts SLN (TX) Mean Residues

### 226 Chemical Name: PCNB Use peanuts Formulation spray SLN (TX) 

### Inputs
Application Rate 5 lbs a.i./acre Half-life 35 days Frequency of Application 30 days Maximum # Apps./Year 2
Outputs

Maximum 56 day Average Concentration Concentration (PPM) (PPM) Short Grass 1862.4 5 1172.74 Tall Grass 853.62 537.51 # days Broadleaf plants/sm Insects 1047.63 659.67 Exceeded F ru it s / po d s /l g i nsec t s 116.40 73.30 on short grass (in first 56)
Avian Acute LC50 (ppm) 54000 0

Chronic NOAEC (ppm) 600 55

Acute RQ Chronic RQ (Max. res. mult. apps.) Short Grass 0.03 3.10 Tall Grass 0.02 1.42 Broadleaf plants/sm Insects 0.02 1.7 5 Fruits/pods/lg insects 0.00 0.19

Mammalian Acute LD50 (mg/kg bw) 5050
Reported Chronic endpoint 10 Enter endpoint units 1 Dose or Diet Rat Calculated Endpoint 200 mg/kg-diet based on standard FDA lab rat conversion

15 g mammal 35 g mammal 1000 g mammal Mammal Chronic Acute RQ Acute RQ Acute RQ RQ (mult. apps) (mult. apps) (mult. apps) Dietary based Short Grass 0.35 0.24 0.06 9.31 Tall Grass 0.16 0.11 0.03 4.27 Broadleaf plants/sm insects 0.20 0.14 0.03 5.24 Fruits/pods/lg insects 0.02 0.02 0.00 0.58 Seeds (granivore) 0.00 0.00 0.00 Chronic RQ dose based Chronic RQ dose based Chronic RQ dose based Short Grass 176.93 122.92 27.94 Tall Grass 81.09 56.34 12.80 Broadleaf plants/sm insects 99.52 69.14 15.71 Fruits/pods/lg insects 11.06 7.68 1.7 5 Seeds (granivore) 2.44 1.7 5 0.3 5 Terresterial Application Residues

0 500 1000 1500 2000

0 4 8 12 16 20 24 2 8 3 2 3 6 4 0 4 4 48 52 DaysConcentration (PPM) Short Grass

Tall Grass

Broadleaf plants/sm Insects Fruits/pods/l

mg/kg-bw Peanuts SLN (TX) #2 Maximum Residues

### 227 Chemical Name: PCNB Use peanuts Formulation spray 

### Inputs
Application Rate 5 lbs a.i./acre Half-life 35 days Frequency of Application 30 days Maximum # Apps./Year 2
Outputs

Maximum 56 day Average Concentration Concentration (PPM) (PPM) Short Grass 659.62 415.3 5 Tall Grass 279.37 175.91 # days Broadleaf plants/sm Insects 349.21 219.89 Exceeded F ru it s / po d s /l g i nsec t s 54.32 34.20 on short grass (in first 56)
Avian Acute LC50 (ppm) 54000 0

Chronic NOAEC (ppm) 600 5

Acute RQ Chronic RQ (Max. res. mult. apps.) Short Grass 0.01 1.10 Tall Grass 0.01 0.47 Broadleaf plants/sm Insects 0.01 0.58 Fruits/pods/lg insects 0.00 0.09

Mammalian Acute LD50 (mg/kg bw) 5050
Reported Chronic endpoint 10 Enter endpoint units 1 Dose or Diet Rat Calculated Endpoint 200 mg/kg-diet based on standard FDA lab rat conversion

15 g mammal 35 g mammal 1000 g mammal Mammal Chronic Acute RQ Acute RQ Acute RQ RQ (mult. apps) (mult. apps) (mult. apps) Dietary based Short Grass 0.12 0.09 0.02 3.30 Tall Grass 0.0 5 0.04 0.01 1.40 Broadleaf plants/sm insects 0.07 0.05 0.01 1.7 5 Fruits/pods/lg insects 0.01 0.01 0.00 0.27 Seeds (granivore) 0.00 0.00 0.00 Chronic RQ dose based Chronic RQ dose based Chronic RQ dose based Short Grass 62.66 43.53 9.89 Tall Grass 26.54 18.44 4.19 Broadleaf plants/sm insects 33.17 23.0 5 5.24 Fruits/pods/lg insects 5.16 3.59 0.81 Seeds (granivore) 1.14 0.81 0.16 Terresterial Application Residues

0 100 200 300 400 500 600 700

0 4 8 1 2 16 20 24 2 8 3 2 3 6 4 0 4 4 4 8 52 DaysConcentration (PPM) Short Grass

Tall Grass

Broadleaf plants/sm Insects Fruits/pods/l

mg/kg-bw Peanuts SLN (TX) #2 Mean Residues

Peanuts Maximum Residues

### 228 Chemical Name: PCNB Use peanuts Formulation spray 

### Inputs
Application Rate 3.2475 lbs a.i./acre Half-life 35 days Frequency of Application 7 days Maximum # Apps./Year 3
Outputs

Maximum 56 day Average Concentration Concentration (PPM) (PPM) Short Grass 2048.58 1324.66 Tall Grass 938.93 607.14 # days Broadleaf plants/sm Insects 1152.33 745.12 Exceeded F ru it s / po d s /l g i nsect s 128.04 82.79 on short grass (in first 56)
Avian Acute LC50 (ppm) 54000 2

Chronic NOAEC (ppm) 600 55

Acute RQ Chronic RQ (Max. res. mult. apps.) Short Grass 0.04 3.41 Tall Grass 0.02 1.56 Broadleaf plants/sm Insects 0.02 1.92 Fruits/pods/lg insects 0.00 0.21

Mammalian Acute LD50 (mg/kg bw) 5050
Reported Chronic endpoint 10 Enter endpoint units 1 Dose or Diet Rat Calculated Endpoint 200 mg/kg-diet based on standard FDA lab rat conversion

15 g mammal 35 g mammal 1000 g mammal Mammal Chronic Acute RQ Acute RQ Acute RQ RQ (mult. apps) (mult. apps) (mult. apps) Dietary based Short Grass 0.39 0.27 0.06 10.24 Tall Grass 0.18 0.12 0.03 4.69 Broadleaf plants/sm insects 0.22 0.15 0.03 5.76 Fruits/pods/lg insects 0.02 0.02 0.00 0.64 Seeds (granivore) 0.01 0.00 0.00 Chronic RQ dose based Chronic RQ dose based Chronic RQ dose based Short Grass 194.62 135.21 30.73 Tall Grass 89.20 61.97 14.08 Broadleaf plants/sm insects 109.47 76.05 17.28 Fruits/pods/lg insects 12.1 6 8.45 1.92 Seeds (granivore) 2.69 1.92 0.38 Terresterial Application Residues

0 500 1000 1500 2000 2500

0 4 8 12 16 20 24 28 32 36 40 44 48 52 DaysConcentration (PPM) Short Grass

Tall Grass

Broadleaf plants/sm Insects Fruits/pods/l

mg/kg-bw

### 229 Chemical Name: PCNB Use peanuts Formulation spray 

### Inputs
Application Rate 3.2475 lbs a.i./acre Half-life 35 days Frequency of Application 7 days Maximum # Apps./Year 3
Outputs

Maximum 56 day Average Concentration Concentration (PPM) (PPM) Short Grass 725.54 469.1 5 Tall Grass 307.29 198.70 # days Broadleaf plants/sm Insects 384.11 248.37 Exceeded F ru it s / po d s /l g i nsec t s 59.7 5 38.64 on short grass (in first 56)
Avian Acute LC50 (ppm) 54000 0

Chronic NOAEC (ppm) 600 10

Acute RQ Chronic RQ (Max. res. mult. apps.) Short Grass 0.01 1.21 Tall Grass 0.01 0.51 Broadleaf plants/sm Insects 0.01 0.64 Fruits/pods/lg insects 0.00 0.10

Mammalian Acute LD50 (mg/kg bw) 5050
Reported Chronic endpoint 10 Enter endpoint units 1 Dose or Diet Rat Calculated Endpoint 200 mg/kg-diet based on standard FDA lab rat conversion

15 g mammal 35 g mammal 1000 g mammal Mammal Chronic Acute RQ Acute RQ Acute RQ RQ (mult. apps) (mult. apps) (mult. apps) Dietary based Short Grass 0.14 0.09 0.02 3.63 Tall Grass 0.06 0.04 0.01 1.54 Broadleaf plants/sm insects 0.07 0.0 5 0.01 1.92 Fruits/pods/lg insects 0.01 0.01 0.00 0.30 Seeds (granivore) 0.00 0.00 0.00 Chronic RQ dose based Chronic RQ dose based Chronic RQ dose based Short Grass 68.93 47.89 10.88 Tall Grass 29.19 20.28 4.61 Broadleaf plants/sm insects 36.49 25.3 5 5.76 Fruits/pods/lg insects 5.68 3.94 0.90 Seeds (granivore) 1.2 5 0.90 0.18 Terresterial Application Residues

0 100 200 300 400 500 600 700 800

0 4 8 1 2 16 2 0 2 4 28 32 3 6 4 0 44 48 5 2 DaysConcentration (PPM) Short Grass

Tall Grass

Broadleaf plants/sm Insects Fruits/pods/l

mg/kg-bw Peanuts Mean Residues

### 230 Chemical Name: PCNB Use potatoes Formulation spray SLN (ID, OR, WA) 

### Inputs
Application Rate 5 lbs a.i./acre Half-life 35 days Frequency of Application 7 days Maximum # Apps./Year 4
Outputs

Maximum 56 day Average Concentration Concentration (PPM) (PPM) Short Grass 3945.80 2584.70 Tall Grass 1808.49 1184.6 5 # days Broadleaf plants/sm Insects 2219.51 1453.89 Exceeded F ru it s / po d s /l g i nsec t s 246.61 161.54 on short grass (in first 56)
Avian Acute LC50 (ppm) 54000 2

Chronic NOAEC (ppm) 600 55

Acute RQ Chronic RQ (Max. res. mult. apps.) Short Grass 0.07 6.58 Tall Grass 0.03 3.01 Broadleaf plants/sm Insects 0.04 3.70 Fruits/pods/lg insects 0.00 0.41

Mammalian Acute LD50 (mg/kg bw) 5050
Reported Chronic endpoint 10 Enter endpoint units 1 Dose or Diet Rat Calculated Endpoint 200 mg/kg-diet based on standard FDA lab rat conversion

15 g mammal 35 g mammal 1000 g mammal Mammal Chronic Acute RQ Acute RQ Acute RQ RQ (mult. apps) (mult. apps) (mult. apps) Dietary based Short Grass 0.74 0.52 0.12 19.73 Tall Grass 0.34 0.24 0.0 5 9.04 Broadleaf plants/sm insects 0.42 0.29 0.07 11.10 Fruits/pods/lg insects 0.0 5 0.03 0.01 1.23 Seeds (granivore) 0.01 0.01 0.00 Chronic RQ dose based Chronic RQ dose based Chronic RQ dose based Short Grass 374.8 5 260.42 59.19 Tall Grass 171.81 119.36 27.13 Broadleaf plants/sm insects 210.8 5 146.49 33.29 Fruits/pods/lg insects 23.43 16.28 3.70 Seeds (granivore) 5.18 3.70 0.74 Terresterial Application Residues

0 500 1000 1500 2000 2500 3000 3500 4000 4500

0 4 8 1 2 16 20 24 2 8 3 2 36 40 44 4 8 5 2 DaysConcentration (PPM) Short Grass

Tall Grass

Broadleaf plants/sm Insects Fruits/pods/l

mg/kg-bw Potato Maximum Residues

### 231 Chemical Name: PCNB Use potatoes Formulation spray 

### Inputs
Application Rate 5 lbs a.i./acre Half-life 35 days Frequency of Application 7 days Maximum # Apps./Yea r 4
Outputs

Maximum 56 day Average Concentration Concentration (PPM) (PPM) Short Grass 1397.47 915.41 Tall Grass 591.87 387.70 # days Broadleaf plants/sm Insects 739.84 484.63 Exceeded F ru it s / po d s /l g i nsec t s 115.09 75.39 on short grass (in first 56)
Avian Acute LC50 (ppm) 54000 0

Chronic NOAEC (ppm) 600 48

Acute RQ Chronic RQ (Max. res. mult. apps.) Short Grass 0.03 2.33 Tall Grass 0.01 0.99 Broadleaf plants/sm Insects 0.01 1.23 Fruits/pods/lg insects 0.00 0.19

Mammalian Acute LD50 (mg/kg bw) 5050
Reported Chronic endpoint 10 Enter endpoint units 1 Dose or Diet Rat Calculated Endpoint 200 mg/kg-diet based on standard FDA lab rat conversion

15 g mammal 35 g mammal 1000 g mammal Mammal Chronic Acute RQ Acute RQ Acute RQ RQ (mult. apps) (mult. apps) (mult. apps) Dietary based Short Grass 0.26 0.18 0.04 6.99 Tall Grass 0.11 0.08 0.02 2.96 Broadleaf plants/sm insects 0.14 0.10 0.02 3.70 Fruits/pods/lg insects 0.02 0.02 0.00 0.58 Seeds (granivore) 0.00 0.00 0.00 Chronic RQ dose based Chronic RQ dose based Chronic RQ dose based Short Grass 132.7 6 92.23 20.96 Tall Grass 56.23 39.06 8.88 Broadleaf plants/sm insects 70.28 48.83 11.10 Fruits/pods/lg insects 10.93 7.60 1.73 Seeds (granivore) 2.42 1.73 0.35 Terresterial Application Residues

0 200 400 600 800 1000 1200 1400 1600

0 4 8 12 1 6 20 24 2 8 32 36 4 0 44 48 5 2 DaysConcentration (PPM) Short Grass

Tall Grass

Broadleaf plants/sm Insects Fruits/pods/l

mg/kg-bw Potato Mean Residues

### 232 Chemical Name: PCNB Use turf Formulation spray SLN (CA, OR, WA) 

### Inputs
Application Rate 43.56 lbs a.i./acre Half-life 35 days Frequency of Application 7 days Maximum # Apps./Year 2
Outputs

Maximum 56 day Average Concentration Concentration (PPM) (PPM) Short Grass 19555.48 12378.53 Tall Grass 8962.93 5673.49 # days Broadleaf plants/sm Insects 10999.96 6962.92 Exceeded F ru it s/ po d s /l g i nsec t s 1222.22 773.66 on short grass (in first 56)
Avian Acute LC50 (ppm) 54000 2

Chronic NOAEC (ppm) 600 55

Acute RQ Chronic RQ (Max. res. mult. apps.) Short Grass 0.36 32.59 Tall Grass 0.17 14.94 Broadleaf plants/sm Insects 0.20 18.33 Fruits/pods/lg insects 0.02 2.0 4

Mammalian Acute LD50 (mg/kg bw) 5050
Reported Chronic endpoint 10 Enter endpoint units 1 Dose or Diet Rat Calculated Endpoint 200 mg/kg-diet based on standard FDA lab rat conversion

15 g mammal 35 g mammal 1000 g mammal Mammal Chronic Acute RQ Acute RQ Acute RQ RQ (mult. apps) (mult. apps) (mult. apps) Dietary based Short Grass 3.68 2.56 0.58 97.78 Tall Grass 1.69 1.17 0.27 44.81 Broadleaf plants/sm insects 2.07 1.44 0.33 55.00 Fruits/pods/lg insects 0.23 0.16 0.04 6.11 Seeds (granivore) 0.0 5 0.04 0.01 Chronic RQ dose based Chronic RQ dose based Chronic RQ dose based Short Grass 1857.77 1290.66 293.33 Tall Grass 851.48 591.5 5 134.4 4 Broadleaf plants/sm insects 1045.00 726.00 165.00 Fruits/pods/lg insects 116.11 80.67 18.33 Seeds (granivore) 25.67 18.33 3.67 Terresterial Application Residues

0 5000 10000 15000 20000 25000

0 4 8 12 1 6 20 24 28 3 2 36 40 4 4 48 52 DaysConcentration (PPM) Short Grass

Tall Grass

Broadleaf plants/sm Insects Fruits/pods/l

mg/kg-bw Turf Maximum Residues

### 233 Chemical Name: PCNB Use turf Formulation spray 

### Inputs
Application Rate 43.56 lbs a.i./acre Half-life 35 days Frequency of Application 7 days Maximum # Apps./Year 2
Outputs

Maximum 56 day Average Concentration Concentration (PPM) (PPM) Short Grass 6925.90 4384.06 Tall Grass 2933.32 1856.78 # days Broadleaf plants/sm Insects 3666.6 5 2320.97 Exceeded F ru it s / po d s /l g i nsect s 570.37 361.04 on short grass (in first 56)
Avian Acute LC50 (ppm) 54000 2

Chronic NOAEC (ppm) 600 55

Acute RQ Chronic RQ (Max. res. mult. apps.) Short Grass 0.13 11.54 Tall Grass 0.05 4.89 Broadleaf plants/sm Insects 0.07 6.11 Fruits/pods/lg insects 0.01 0.95

Mammalian Acute LD50 (mg/kg bw) 5050
Reported Chronic endpoint 10 Enter endpoint units 1 Dose or Diet Rat Calculated Endpoint 200 mg/kg-diet based on standard FDA lab rat conversion

15 g mammal 35 g mammal 1000 g mammal Mammal Chronic Acute RQ Acute RQ Acute RQ RQ (mult. apps) (mult. apps) (mult. apps) Dietary based Short Grass 1.30 0.91 0.21 34.63 Tall Grass 0.55 0.38 0.09 14.67 Broadleaf plants/sm insects 0.69 0.48 0.11 18.33 Fruits/pods/lg insects 0.11 0.07 0.02 2.85 Seeds (granivore) 0.02 0.02 0.00 Chronic RQ dose based Chronic RQ dose based Chronic RQ dose based Short Grass 657.9 6 457.11 103.89 Tall Grass 278.67 193.60 44.00 Broadleaf plants/sm insects 348.33 242.00 55.00 Fruits/pods/lg insects 54.18 37.64 8.56 Seeds (granivore) 11.98 8.56 1.71 Terresterial Application Residues

0 1000 2000 3000 4000 5000 6000 7000 8000

0 4 8 12 1 6 20 24 28 32 36 40 4 4 48 52 DaysConcentration (PPM) Short Grass

Tall Grass

Broadleaf plants/sm Insects Fruits/pods/l

mg/kg-bw Turf Mean Residues

### 234 APPENDIX H: ECOLOGICAL RISK ASSESSMENT
A means of integrating the results of exposure a nd ecotoxicity data is called the quotient method. For this method, risk quotients (RQs ) are calculated by dividing expos ure estimates by ecotoxicity values, both acute and chronic.
RQ = EXPOSURE/TOXICITY
RQs are then compared to OPP's levels of con cern (LOCs). These LOCs are criteria used by OPP to indicate potential risk to nontarget organisms and th e need to consider regulatory action. The criteria indicate that a pesticide used as directed has the potential to cause adverse effects on nontarget organisms. LOCs currently address the following risk presumption categories: (1) acute high - potential for acute risk is high, regulatory action may be warranted in addition to restricted use classification (2) acute restricted

use - the potential for acute risk is high, but this may be mitigated through restricted use classification (3) acute endangered species - the potential for acute risk to endangered species is high, regulatory action may be warranted, and (4) chronic risk - the potential for chronic risk is high, regulatory action may be warranted. Currently, EFED does not perform assessments for chronic ri sk to plants, acute or chronic risks to nontarget insects, or chronic risk from granular/bait formulations to mammalian or avian species.
The ecotoxicity test values ( i.e. , measurement endpoints) used in the acute and chronic risk quotients are derived from the results of required studies. Exam ples of ecotoxicity values derived from the results of short-term laboratory studies that assess acute effects are: (1) LC 50 (fish and birds) (2) LD 50 (birds and mammals) (3) EC 50 (aquatic plants and aquatic invertebrates) and (4) EC 25 (terrestrial plants). Examples of toxicity test effect levels derived from the results of long-term laboratory studies that assess chronic effects are: (1) LOEC (birds, fish, and aquatic invertebrates) (2) NOEC (birds, fish and aquatic invertebrates) and (3) MATC (fish and aquatic invertebrates). For birds, mammals, and all aquatic organisms, the NOEC is the ecotoxicity test value used in assessing chronic ri sk. Other values may be used when justified. Risk presumptions, along with the corresponding RQs and LOCs are summarized in Tables G-1 through G-3

. Table G-1. Risk presumptions for terrest rial animals (birds and wild mammals) Risk Presumption RQ LOC Acute High Risk EEC 1 /LC 50 or LD 50 /ft 2 or LD 50 /day 3 0.5
Acute Restricted Use EEC/LC 50 or LD 50 /ft 2 or LD 50 /day (or LD 50 < 50 mg/kg) 0.2

Acute Endangered Species EEC/LC 50 or LD 50 /ft 2 or LD 50 /day 0.1
Chronic Risk EEC/NOEC 1
1 abbreviation for Estimated Environmental Con centration (ppm) on avian/mammalian food items
2 mg/ft 2 3 mg of toxicant consumed/day LD 50 * wt. of bird LD 50 * wt. of bird

### 235 Table G-2. Risk presumptions for aquatic animals Risk Presumption RQ LOC Acute High Risk EEC 1 /LC 50 or EC 50 0.5
Acute Restricted Use EEC/LC 50 or EC 50 0.1 Acute Endangered Species EEC/LC 50 or EC 50 0.05
Chronic Risk EEC/NOEC 1

1 EEC = (ppm or ppb) in water
Table G-3. Risk presumptions for plants Risk Presumption RQ LOC Terrestrial and Semi-Aquatic Plants Acute High Risk EEC 1 /EC 25 1 Acute Endangered Species EEC/EC 05 or NOEC 1 Aquatic Plants Acute High Risk EEC 2 /EC 50 1 Acute Endangered Species EEC/EC 05 or NOEC 1
1 EEC = lbs ai/A
2 EEC = (ppb/ppm) in water
Exposure and Risk to Nontarget Terrestrial Animals
For pesticides applied as a nongranular product ( e.g. , liquid, dust), the estimated environmental concentrations (EECs) on food items followi ng product application are compared to LC 50 values to assess risk. The predicted peak and mean residues of a pes ticide that may be expectedto occur on selected avian or mammalian food items immediately following a direct single application at 1 lb ai/A is presented in Table G-4

. Table G-4. Estimated environmental concentrations on avian and mammalian food items (ppm) following a single applications at 1 lb ai/A

. Application Rate Food Items EEC (ppm) Predicted Maximum Residue 1 EEC (ppm) Mean 1

1 lb a.i./A Short grass 240 27 Tall grass 110 10 Broadleaf/forage plants and small insects 135 11
Fruits, pods, seeds, and large insects 15 1

### 236 1 Predicted maximum and mean residues are for a 1 lb ai/a application rate and are based on Hoerger and Kenaga (1972) as modified by Fletcher et al. (1994).
Predicted residues (EECs) resulting from multiple applications are calculated in various ways. Uncertainties in the terrestrial EECs are primarily a ssociated with a lack of data on interception and subsequent dissipation from foliar surfaces. When scien tifically valid, statistically robust data are not available EFED relies on a default half-life value of 35 days. The use of the 35 day half-life is based on the highest reported value (36.9 days) re ported by Willis and McDowell (1987).