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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 Chief
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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 groundwater. 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 despite the volatility of PCNB and limited mobility 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 25o

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 estimated concentrations are likely overestimated,

particularly for uses involving foliar application, such as on turf, where volatilization 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-treated
4

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 LD50 exceeded 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.
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Acknowledgment

The Environmental Fate and Effects Division would like to thank Syracuse Research Corporation

(Mario Citra, Antonio Quiñones-Rivera, Molly Ramsey, 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 degradates. 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 conducting a more refined aquatic risk assessment. The

contributions made by these individuals improved OPP’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 with EPA’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 ecotoxicity 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.
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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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
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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-chemical 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 . . . . . . . . . . . . . 137
8

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-chemical 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
9

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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
10

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 likelihood of adverse effects (risk) to nontarget

endangered/threatened and nonendangered animals and plants that could potentially impact the reregistration

eligibility decision under the Federal Insecticide, Fungicide and Rodenticide Act, the Food Quality Protection

Act, and the Endangered Species Act. Over the course 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 environmental fate and ecological effects of PCNB and its

degradates. Because of over 1,700 use-pattern combinations 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 Division (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 identified several major crops based on pounds of PCNB

used (turf, peanuts, cabbage [cole crop], potatoes and cotton) on which to base its assessment.

The risk assessment considers formulations used for 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 concentrations, 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 consumption 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 undergoing 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 accounted for 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 for turf than the one modeled, it is an allowed usage

only in CA, WA, and OR. This assessment is not intended to represent a site or time-specific analysis, i.e.

assessments are intended to represent a national-level exposure based on vulnerable soils as opposed to being

a regionally specific exposure assessment. Likewise, the most sensitive 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 studies are used to evaluate the potential of a pesticide to

cause adverse effects, to determine whether further testing 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 water 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 environmental concentrations used in terrestrial ecological risk

assessment are based on PCNB alone for terrestrial animals. 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 (including volatiles) and assumed to be of equal toxicity

to the parent. No plant toxicity data were available for PCNB; thus, the ecological risk to plants cannot be

evaluated.

This screening-level assessment is not intended to provide a site-specific understanding of particular

PCNB uses and their effects on specific species. However, some refinements, e.g. Tier II aquatic exposure

assessments, have been incorporated into this assessment. Additionally, where uncertainties exist, they have

been identified along with possible avenues to address the uncertainties in terms of additional data. Because

the majority of PCNB use on turf is on golf course turf, which is the overall major use for PCNB, estimated

surface water concentrations for both the drinking water and ecological exposure assessments were adjusted

to account for pesticide use on less than the total turf acreage. However, the values used in the risk

assessment for turf use are based on non-adjusted EEC’s, as there are labeled turf uses other than golf course

turf. The adjusted values for golf course 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 degradates 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 since 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 aquatic plant toxicity estimates for a number of chlorinated

benzenes.

The conceptual model used to depict the ecological risk associated with PCNB was initially fairly

generic and assumed that as a pesticide, PCNB was capable of affecting terrestrial and aquatic animals

provided environmental concentrations were sufficiently elevated as a result of labeled uses. However,

through an iterative process of examining fate and effects data, the conceptual model has been refined to

reflect the exposure pathways and the organisms for which risk is most likely. Based on OPP’s screeninglevel assessment, the refined conceptual model for depicting the risks of PCNB to nontarget animals is one

that primarily focuses on birds and the aquatic environment 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/growth 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 chronic effects in mammals. Thus the predominate

concern for terrestrial animals focuses 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 exposure 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-based
12

approach does not provide a quantitative estimate of likelihood 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 broad-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 (bedding, 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 concentrate, 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), particularly 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 (preventative and residual) against soil-borne diseases prior

to infection of the plants. To date, resistance to PCNB has reportedly not been observed. 

Use Characterization

PCNB is a contact fungicide that provides preventative and residual protection against soil-borne

diseases. Based on the current labels, it will be applied in the environment either as a seed treatment or to

soil. Applications to soil will be mainly as a ground spray 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 (AMVAC 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 for the 7/18/2001 SMART Meeting) include broadcast or

row drench, pre-emergent broadcast, row spray, in-furrow (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 are cotton, peanut, soybean and wheat. 

Based on information obtained from the National Center 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 years 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 approximately 31,000 lbs applied to approximately 6000 acres

of peanuts (NCFAP, 2000).

As reported in the Quantitative Usage Analysis (dated 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 active ingredient (BEAD, 2001). Crops with the highest

percentage of their total U.S. planted acres treated with 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 Great 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 reported 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 active 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 and county for benchmark year 1992. 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.

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 several decades. In 1997, just over 800,000 lbs of PCNB

were applied, down from 1.6 million lbs in 1992 (NCFAP, 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 Analysis for PCNB for the years of 1990 through 2000,

the estimated average annual total domestic usage was reported to be approximately 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 patterns 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 and 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 that pesticide uses/needs are affected 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, pentachloronitrobenzene (PCNB) is, in general,

expected to be a persistent, moderately 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.

Table 1 summarizes the physico-chemical properties of PCNB, a relatively high molecular weight compound

with low water solubility. More complete information on the environmental fate studies can be located in

APPENDIX B.

Table 1. General fate and physical-chemical properties 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) t1/2 = 2.5 days

t1/2 = 26.8 hours

MRID’s 42606201, 42606202

MRID 42336201

 Soil Photolysis Half-life stable MRID’s 41004801, 41713201

 Aerobic Soil Metabolism Half-life t1/2 = 77, 189 days (parent only);

t1/2 = 489, 1012 days (parent plus

 PCA) 

t1/2 = 983, 1052 days (total residues)

MRID’s 42911902, 41384501, 41713202,

42112801

 Anaerobic Soil Metabolism Half-life t1/2 = 9 days, <30 days (DT50; parent

only); 

t1/2 = 410 days (parent plus

 PCA) 

t1/2 = 334 days (total residues) 

MRID’s 41203602, 42094401, 41384301,

41686001, 41713202, 42112802)

 Organic Carbon Partition Coefficient

(Koc)

1588, 2912, 3870, 17508 MRID 41648201

 Soil Partition Coefficient (Kd, 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, the major degradates of PCNB in the environment

are: pentachloroaniline (PCA) and pentachlorothioanisole (PCTA), and pentachlorobenzene (PCB; which

is also present as an impurity); minor degradates are pentachlorothioanisole sulfoxide (PCTASO), and

pentachlorothioanisole sulfone (PCTASO2). PCNB also contains the manufacturing contaminant

hexachlorobenzene (HCB), which was detected 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 (either 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 incorporated. 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 volatility 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 amounts 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 volatilize 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 that was lost from soil during 10 months of incubation

was due to volatilization, with the remaining losses attributed 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-m3

-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 shallow surface water under favorable light conditions.

Photodegradation of PCNB in surface water is moderately 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 determined 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, caution 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 effectively 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 slowly in aerobic soil, with half-lives of 4.7-9.7 months

reported by Wang and Broadbent (1972) and half-lives of 213, 425, 535 and 699 days reported by Beck and

Hansen (1974). While PCNB is only expected to biodegrade slowly in most aerobic environments, it is

biodegraded more rapidly (DT50's of <30 days in soil based on submitted data) in anaerobic soil environments.

Although guideline study data on the aquatic metabolism of the compound were not submitted, data in the

literature showed a rapid biodegradation of PCNB in anaerobic estuarine 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 rapidly
18

in the plots in which the pesticide was not incorporated, 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 studies 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 manufacturing 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 had been applied over the previous 5 to 11 years, Beck

and Hansen (1974) determined field half-lives ranging 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 and D3) 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 adsorption 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, PCNB 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 immobile 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 Koc 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 leached into the 6- to 12-inch soil depth at some sites. 

There is a potential for PCNB to reach surface water through spray drift when applied using ground

spray, as would be utilized for many of the labeled uses. Greater spray drift will be associated with foliar

applications (such as to turf), while in-furrow applications (such as to cotton and peanuts) should result in

relatively lower levels of drift. Uses such as seed treatment 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, over 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. However, 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 the literature, PCNB will rapidly be degraded to PCA

in anaerobic sediment, with subsequent transformation of that compound to lesser-chlorinated anilines

(Susarla et al., 1996). However, Schauerte et al. (1982) only reported a quantitative 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 time. 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 products 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 [14C]PCNB at #1.0 ppb

were bioaccumulated to a greater extent in the viscera, 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 literature, 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 reported for aquatic plants.

Korte et al. (1978) reported BCF values of 14,000X and 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 used 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 parent and appropriate degradate(s) were summed, and halflives were calculated normally (using first-order linear regression). Degradation kinetics for the parent and

the various degradates were not determined separately and then combined. The approach used by EFED,

while conservative, should not overly lengthen the half-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 water 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 recalculated 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 volatilization 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 occurred during the initial 24 hours following treatment.

Additionally, the use of an in-furrow application (or other type of incorporation) should theoretically reduce

the level of volatilization of PCNB in the field. In submitted field studies, dissipation was more rapid (halflife range of 39-57 days) in the plots in which the pesticide 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 half-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 in the DWA using concentration data (including

volatiles) for the parent compound plus the degradate PCA, the recalculated aerobic soil metabolism half-lives

for the parent and parent/PCA combination are 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 using
20

concentration data (including volatiles) for total residues (defined here as including only the following

compounds of interest: PCNB, PCA, PCTA, PCB, PCP, PCTASO, PCTASO2 and/or HCB) for use as

estimated environmental concentrations for the ecological exposure assessment, the recalculated aerobic soil

metabolism half-lives for total residues were 983 days 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 for 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 degradates PCB and PCP are not presented here as PCNB is not

the single source for these compounds in the environment and the available monitoring data could not be

linked to the use of PCNB.

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 basins, 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 sediment at 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 highest usage of PCNB, the compound was not detected in

the bed sediments at any of the NAWQA sampling sites 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 Institute 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 treated 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 PCA 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/m3

 (Hawthorne et al., 1996). In air monitoring

studies done in Canada, PCNB was detected over Saskatchewan 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/m3

) collected during a 3-month

period in the summer of 1994 over Regina, 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, Canada
21

(Thompson et al., 1997). The detection of PCNB in the 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/m3

, a maximum subchronic concentration of 18 ng/m3,

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 organochlorines 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 modeling to determine the Estimated Drinking Water Concentrations (EDWC)

for the drinking water assessment and the Estimated Environmental Concentrations (EEC) for the ecological

risk assessment; and specifies which values are to be used 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 generated using the Tier 1 screening model SCI-GROW.

The EDWC’s recommended by OPP for use in the human health risk assessment for PCNB are presented in

Table 2. Reported values represent the maximum contamination 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 OPP for use in the ecological risk assessment for PCNB

are presented in Table 3. The general fate and physical-chemical property data used as the source of the input

parameter values for modeling were obtained from the guideline studies and other submissions from the

registrant.
22

Table 2. EDWC’s for the drinking water assessment 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 model with a foliar/ground spray to turf in Pennsylvania application 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 cabbage use acute

concentration. However, as this is greater than the aqueous solubility of 440 ppb at 25o

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 ecological risk assessment based on PCNB1 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 conducted 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 metabolism study. The drinking water assessment conducted was

also for the manufacturing impurity/minor degradate PCB. The assessment essentially concluded that, based

on both modeling results and monitoring data, both HCB and PCB are relatively unlikely to contaminate

groundwater and that long-term concentrations in surface 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 values used here were obtained from specific labels, as

indicated in Table 2. Another change affecting the EDWC’s was the correction of model output values (for
23

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 the 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 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. 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 performed to determine estimated water

concentrations for the human health (drinking water component) risk assessment and the ecological risk

assessment. The human drinking water EDWCs were determined using the standard index reservoir scenario

in which a 172-ha field drains into a 5.3-ha reservoir and percent cropped area (PCA) is taken into

consideration. The PCA for each of the four crops modeled 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 standard pond scenario in which a 10-ha field drains into

a 10,000-m2

 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 Applications (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 (Kd; mL/g) 15.5 MRID 41648201; lowest non-sand Kd

Aerobic Soil Metabolism Half-life (days) t1/2 = 1555 days (parent plus PCA) MRID’s 42911902, 41384501,

41713202, 42112801; represents the 90th

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-m3

-mol Product chemistry data

Solubility in Water at 25o

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) t1/2 = 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)

t1/2 =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, 40972601
Parameter 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 results 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 4401 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 solubility limit should be used instead.

Table 6. SCI-GROW2 input parameter values and 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) t1/2 = 750.5 days (parent plus

 PCA; average of two values)

Organic Carbon Partition Coefficient (Koc) 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 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 15th was chosen to represent a post-emergent application (generally done prior to
26

Thanksgiving) made during the part of the growing season in which snow mold occurs (November through

April). Incorporation of the pesticide 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).

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 terms 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 15th was 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 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 Mississippi cotton standard scenarios are based on the

registrant’s information that PCNB is used on those crops predominantly in the south. An application date

of April 15th was chosen for a pre-plant application to peanuts based on a planting time of April 20th to May

20th. An application date of April 20th was chosen for a pre-plant application to cotton based on a May 1st

planting 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 incorporation 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 Northwest and the Great Lakes regions. An application date of May

20th was chosen for a pre-plant application to potatoes based on a planting time of April to June 10th for

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/application, applied twice (total application rate of 65.3 lb a.i./A) at a 21-

day interval as a post-emergent foliar/ground spray application. 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 standard 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/EXAMS modeling and the resultant EDWCs for the five

use scenarios (Pennsylvania turf, North Carolina peanuts, 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 Effects Division’s Metabolism Assessment Review

Committee (MARC), the reviewer conducted the drinking water modeling to account for the parent
1

 Personal communication, Lawrence Burns, Office of Research and Development, United States Environmental Protection Agency,

Athens, GA

27

compound plus PCA, a degradate considered to be a residue of concern. In this approach, the aerobic and

anaerobic soil metabolism half-lives were calculated using 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 calculated using parent compound concentration data only. The

lack of information on the photolysis rate of PCA 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 used in 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 modeling 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 the 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) available on which precipitation reactions can start. Due

to the restrictions in place in the EXAMS model, it cannot simulate an aqueous concentration that saturates

the water body at the aqueous solubility limit of the compound, as EXAMS does not use the solubility input

parameter as the direct upper limit on concentration. In general, the model disregards a portion of the mass

of the compound once the concentration of that compounds 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 EXAMS1

. Unfortunately, the removal of mass from the system when onehalf the solubility is exceeded tends to overestimate the removal of the substance from the environment. In

addition, it prevents EXAMS from reflecting concentrations in the environment higher than one-half the

solubility, even though they can physically occur. Consequently, OPP’s policy is to multiply the solubility

by 10 (to obtain the input parameter value) to prevent 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 25o

C). In cases where the resulting EDWC’s are

greater than the solubility, they are reported as equivalent to the solubility limit (440 μg/L at 25o

C). It is

thought that this better reflects the fate of the pesticide 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 application) may result in higher values, OPP does not have a

standard modeling scenario available to simulate application to (ornamental) bulb crops. Since the model
28

results for turf were an estimated acute concentration 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 health risk assessment. 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 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 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 26.5%, from the previous value of 586.4 ppb to

431.9 ppb, when volatilization is accounted for. However, because the solubility limit of 440 ppb is used

for the EDWC (in lieu of the 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%, 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 contained 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 application, 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 Concentrations 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 ecological exposure assessments were adjusted to account for

pesticide use on less than the total turf acreage. Golf course facilities consist 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, conservation 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 farm, residential, right-of-ways, (other) recreational,

or any other turf uses. As the PCNB labels allow for other 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 a
29

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 used in the drinking water assessment as well as to the EEC’s

used in the ecological exposure assessment. The GCAF has not been applied to the groundwater values

determined using the Tier 1 model SCI-GROW, because the model is based on a treated field rather than a

watershed.

While the implementation of a GCAF will allow for a modification of the EDWC’s and EEC’s

determined by EFED Tier 1 and Tier II aquatic exposure models for a golf course turf use scenario, it is not

a complete remedy for the uncertainties involved with estimating surface water concentrations associated with

the use of a pesticide on a golf course. There are several aspects of pesticide use on golf course turf that may

result in the model scenario underestimating surface water 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 water concentrations will be reduced

in equal proportion to the reduced level of acreage treated; supporting data for this assumption are not

available.

Table 7. Adjusted Tier II EDWCs and EEC’s for PCNB1

 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. 2The actual output value from PRZM/EXAMS was 587.7 ppb for the turf

use acute concentration. However, as this was greater than the aqueous solubility of 440 ppb for PCNB, the solubility limit was used in the drinking

water assessment. For the refinement, the adjustment factor was applied to the model output value (i.e., 587.7) rather than to the solubility limit.

Groundwater

Estimates for groundwater concentrations were made using the Tier I screening model SCI-GROW2

(Screening Concentrations in Ground Water). SCI-GROW2 is based on a regression approach which relates

the concentrations found in groundwater in Prospective Groundwater studies to the aerobic soil metabolism

rate and soil-water partitioning properties of the chemical. The model 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 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. 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). As
30

discussed previously in the Drinking Water EDWC’s section, the reviewer conducted the 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 concern with regard to human health. 

The data presented in the table include EDWC’s for 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, the groundwater EDWC for parent PCNB only (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 groundwater 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 addition to the parent compound. The degradate PCA

was accounted for by the recalculation of the parent half-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 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 OPP modeling requirements, data from aerobic and anaerobic aquatic metabolism

studies are generally considered more reliable 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 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 information 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. 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 environmental

exposure (particularly with regard to PCP) associated with the use of PCNB.

PCP has been reported to be a “major” degradate 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 stated that PCP is a soil metabolite of PCNB. Attempts
31

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 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 investigations, the study authors 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 present in the aqueous phase of the soil extract; however, they did not attempt to

quantify the residues. The differences in the experimental conditions of the initial and subsequent

investigations were not published. In a combined submission from Amvac & Crompton Corporation, the

registrants submitted data (based on their own laboratory studies) which demonstrated that, had PCP been

present in the initial investigations of Murthy and Kaufman, the compound should have been detected in the

organic phase in the initial experiments. They demonstrated 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 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 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 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-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 under which PCP can form in the environment, but

that it 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, 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 and 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 Data
32

NAWQA monitoring data for PCNB and PCA in water 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.

To supplement the monitoring data available from standard sources, 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,

as PCP is extensively used 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 compounds PCA, PCB and PCP were monitored 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 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 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 residues (defined here to include the parent, PCA,

PCTA, PCB, PCP, PCTASO, PCTASO2 and/or HCB, including volatiles). The EEC’s are, therefore, subject

to the same uncertainties associated with the use of parent compound data for aqueous photodegradation and

adsorption input values, as well as a potential for underestimation 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 predicted 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 exposure 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 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 25.4% when volatilization is accounted for. Chronic

ecological exposures for turf use (21- and 60-day values) 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 Applications (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 (Kd; mL/g) 15.5 MRID 41648201; lowest non-sand Kd

Aerobic Soil Metabolism Half-life (days) t1/2 = 1124 days (total residues) MRID’s 42911902, 41384501,

41713202, 42112801; represents the 90th

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-m3

-mol Product chemistry data

Solubility in Water at 25o

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) t1/2 = 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)

t1/2 = 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, 40972601
35

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 concentrationsa

(in ppb) of total residues (PCNB, PCA, PCTA, PCB, PCP, PCTASO, PCTASO2 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%

a

 concentrations 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, banded, chemigation, and seed treatment. The combination

of many uses and assorted application methods can potentially result in various routes of non-target exposure

to terrestrial and aquatic organisms. For this terrestrial 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 indoors 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 route 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 has been eating only treated seed. This approach uses

the acute oral toxicity for the toxicity endpoint (LD50). The second method also uses the acute oral dose for

toxicity (LD50) 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 information has been collected for

other seed treatment pesticides, and in order to ensure 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 assessments by OPP and which were obtained from crop profiles or through discussions with

various pesticide registrants. Maximum seeding rates were used from various crop profiles (these profiles can be found at

http://pestdata.ncsu.edu/cropprofiles/cplist.cfm?org=crop). When the registrant-submitted value was higher than those found in the crop profiles, they

were used preferentially. 

b

 Label rates

c

 Maximum application rate of PCNB (lbs ai/acre) =( Maximum seeding 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 LD50 can be adjusted for body weight based on the formula (EQ 2)

recommended by Mineau et al. 1996:

where adjusted LD50 is the median 50% lethal dose for the species being assessed, LD50 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 LD50 from the test

species LD50 (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 LD50 of

greater than 2250 mg kg-1, the adjusted LD50 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 generally 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 LD50 (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 adjusted 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 LD50 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 LD50

(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 chemical 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 concentrations (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 (cole 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 subsequent dissipation from foliar surfaces. When data are

absent, as in this case, EFED assumes a 35-day foliar dissipation 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 following product application are compared to LC50 values to assess

risk. Uses and associated application rates modeled for terrestrial exposure assessments are presented in
39

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 application (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 purposes since the registrants have provided information

indicating that there are no foliar uses of PCNB; for cotton, PCNB is applied to the ground and is then

incorporated.

Table 11a. Selected uses and maximum PCNB application rates modeled for terrestrial exposure

assessment.

Crop Rate

(lb ai/A)

No. of

Applic.

(interval)

Timing Formulation Application Type Notes

cabbage1 22.5 1 postplant wettable powder soil band trt.

(sprayer)

applic. is to

soil, not foliage

peanuts3 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)

potatoes4 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) foliar
40

Table 11b. Estimated environmental concentrations 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 Hoerger 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 = 7
41

ECOLOGICAL EFFECTS CHARACTERIZATION

APPENDIX E discusses the 34 ecological toxicology studies submitted by the registrant for

consideration: 76% were classified as core (acceptable) and having provided useful information toward

fulfilling the required guideline data. The remaining (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 limited 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 assumption is used for fish and amphibians. 

PCNB is practically non-toxic to honey bees, birds 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 invertebrates. 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 toxicity data for terrestrial organisms exposed to

pentachloronitrobenzene.

Species

Acute Toxicity Chronic Toxicity

LD50

(ppm)

Acute Oral

Toxicity

(MRID)

5-day

LC50

(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 reproductive 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 LC50

(mg/L)

48-hr EC50

(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 effects 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 received no specific toxicity data from the registrant(s)

with which to evaluate the toxicity of those metabolites. 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 evaluated for inclusion into this chapter. Citations

and abstracts were obtained by searching the following commercial or publicly available databases:

TOXLINE, MEDLINE, BIOSIS previews, AGRICOLA, 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 species 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 difference 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 potential 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 pentachlorophenol listed in the ECOTOX on-line

database. 

Scientific Name

(Common Name)

Acute Toxicity LC50

(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 registrant-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 records, there were two studies that examined the

germination EC50 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/cm3

 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 showed 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 searches
44

found a study that described tests on white leghorn chickens 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 chicks hatched from fertile eggs significantly 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 with 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 pentachlorophenol listed in the ECOTOX on-line

database. 

Scientific Name

(Common Name)

Acute Toxicity LC50

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 registrant-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 output, of which 16 records were already submitted to

OPP in support of the registration of PCNB. Another 26 records were bioconcentration studies to various

fish and green algal species. Sixteen records were neither bioaccumulation or LC50 / EC50 tests, although they

contained toxicity endpoints of an unspecified nature. Finally, there were five records that described LC50

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 the early life stages of these organisms. The sand shrimp
45

(Crangon septemspinosa) exposed to PCA for 96 hours exhibited an LC50 = 300 μg/l (McLeese et al., 1979).

Because of this apparent aquatic toxicity and lack of submitted data on this chemical, additional data on the

acute and chronic toxicity of PCA to aquatic organisms would reduce uncertainties in this risk assessment.

Growth, development, and reproduction were impaired in aquatic 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 LD50 = 1.5 mmol/m3

 (Abernethy et al., 1986). Opossum

shrimp (Americamysis bahia) exhibited an LC50 = 160 μg/l in a 96-hour exposure experiment (U.S. EPA,

1978). Tests on chironomids resulted in a 48-hour LC50 = 230 μg/l (Roghair et al., 1994). Acute toxicity

values for PCB show that the LC50 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 species of aquatic vertebrates and invertebrates. LC50

values of PCP in several copepod species ranged from approximately 50 to 230 μg/l (Willis, 1999). Early

larval stage copepods were similarly sensitive to PCP as were the adults. The amphipods, Chaetogammarus

marinus and Crangonyx pseudogracilis, had LC50 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 LC50 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).

LC50 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, reproduction 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 amphibians (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

(ASsessment Tools for the Evaluation of Risk) was developed by the U.S. EPA Mid-Continent Ecology

Division, Duluth, MN (MED-Duluth) to assist regulators in performing ecological risk assessments. ASTER

is an integration of the AQUIRE (AQUatic toxicity Information REtrieval) toxic effects database and the

QSAR (Quantitative Structure Activity Relationships) system, 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 environmental partitioning. ASTER is designed to provide

high quality data for discrete chemicals, when available 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 Input Line 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 EC50 values for freshwater nonvascular plants suggest that chlorinated benzene toxicity

increases with the number of chlorines.
46

Table 16. ASTERa model-generated 96-hr EC50 estimates in mg/L (ppm) for selected chlorinated

benzene compounds.

Species Chemical measurement endpoint 96-hr EC50

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

a

 ASTER (ASsessment Tools for the Evaluation of Risk) was developed by the U.S. EPA Mid-Continent Ecology Division, Duluth, MN
47

RISK CHARACTERIZATION

Risk Estimation

To evaluate the potential risk to nontarget organisms from the use of PCNB products, risk quotients

(RQs) are calculated from the ratio of estimated environmental concentrations (EECs) to ecotoxicity values.

RQs are then compared to levels of concern (LOC’s) used by OPP to indicate potential 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 95th

percentile of the expanded data set. Risk quotients are based on the most sensitive LC50 and NOAEC for birds

(in this instance, bobwhite quail) and LD50 for mammals (based on lab rat studies). 

Acute and chronic risk quotients were calculated following the procedure outlined in APPENDIX

G and were then compared to LOC’s. Acute restricted 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 while the acute risk to endangered species LOC (RQ$0.1) is

exceeded for birds feeding on tall grasses following application to turf. The application rate on cole crops

(cabbage) also exceeded the acute risk to endangered species LOC. Importantly, the LC50 for Bobwhite quail

used in the RQ calculations was greater than the highest concentration tested (i.e., LC50>54,000 ppm);

therefore, all acute RQ values are less than the calculated value. For this 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 scenario produced the highest RQ values,

followed by cole crops, potatoes, and peanuts. The mammalian RQ values were calculated using a rat LD50

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 considers 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-sized (1000 g) mammals, chronic RQ values were below

the chronic risk LOC at the maximum application rates 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 the annual PCNB applications in the United States. 

Table 17. Avian acute and chronic risk quotients for selected uses of nongranular products of PCNB

based on a bobwhite quail LC50 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/LC50)

Chronic RQ

(EEC/

NOAEC)

Cabbage

22.5

(1 / NA)

Short grass 5400 1913 <0.10d 9.0e

Tall grass 2475 810 <0.05 4.1e

Broadleaf plants/small insects 3038 1013 <0.06 5.1e

Fruits, pods, seeds, and large

insects 338 158 <0.01 0.56

Peanuts

SLN (TX)

10

(1 / NA)

Short grass 2400 850 <0.04 4.0e

Tall grass 1100 360 <0.02 1.8e

Broadleaf plants/small insects 1350 450 <0.03 2.3e

Fruits, pods, seeds, and large

insects 150 70 <0.01 0.25

SLN (TX)

5

(2 / 30)

Short grass 1862 660 <0.03 3.1e

Tall grass 854 279 <0.02 1.4e

Broadleaf plants/small insects 1048 349 <0.02 1.8e

Fruits, pods, seeds, and large

insects 116 54 <0.01 0.19

3.2475

(3 / 7)

Short grass 2049 726 <0.04 3.4e

Tall grass 939 307 <0.02 1.6e

Broadleaf plants/small insects 1152 384 <0.02 1.9e

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 6.6e

Tall grass 1808 592 <0.03 3.0e

Broadleaf plants/small insects 2220 740 <0.04 3.7e

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 <0.36c 33e

Tall grass 8963 2933 <0.17d 15e

Broadleaf plants/small insects 11000 3667 <0.20c 18e

Fruits, pods, seeds, and large

insects 1222 570 <0.02 2.0e
49

a

 estimated environmental concentrations predicted using 1st-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), intermediate (35-g) and large (1,000-g) mammals feeding

on short or tall grass, broadleaf plants/small insects, fruits/pods/large insects and seeds exposed to

PCNB following single and multiple applications based on a rat LD50 >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 <1.0a <0.71a <0.16c

Tall grass 2475 <0.47b <0.32b <0.07

Broadleaf plants/small insects 3038 <0.57a <0.40b <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 <0.45b <0.31b <0.07

Tall grass 1100 <0.21b <0.14c <0.03

Broadleaf plants/small insects 1350 <0.25b <0.18c <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 <0.35b <0.24b <0.06

Tall grass 854 <0.16c <0.11c <0.03

Broadleaf plants/small insects 1048 <0.20b <0.14c <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 <0.39b <0.27b <0.06

Tall grass 939 <0.18c <0.12c <0.03

Broadleaf plants/small insects 1152 <0.22b <0.15c <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 <0.74a <0.52a <0.12c

Tall grass 1808 <0.34b <0.24b <0.05

Broadleaf plants/small insects 2220 <0.42b <0.29b <0.07

Fruits, pods, seeds, and large

insects 247 <0.05 <0.03 <0.01
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

50

Seeds (granivores) 247 <0.01 <0.01 <0.01

Turf

SLN (CA, OR,

WA)

43.56

(2 / 7)

Short grass 19555 <3.7a <2.6a <0.58a

Tall grass 8963 <1.7a <1.2a <0.27b

Broadleaf plants/small insects 11000 <2.1a <1.4a <0.33b

Fruits, pods, and large insects 1222 <0.23b <0.16c <0.04

Seeds (granivores) 1222 <0.05 <0.04 <0.01 a

 exceeds 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 513a 356a 81a

Tall grass 2475 235a 163a 37a

Broadleaf plants/small insects 3038 289a 200a 46a

Fruits, pods, and large insects 338 32a 22a 5a

Seeds (granivores) 338 7a 5a 1a

Peanuts

SLN (TX)

10

(1 / NA)

Short grass 2400 228a 158a 36a

Tall grass 1100 105a 73a 17a

Broadleaf plants/small insects 1350 128a 89a 20a

Fruits, pods, and large insects 150 14a 10a 2a

Seeds (granivores) 150 3a 2a 0.45

SLN (TX)

5

(2 / 30)

Short grass 1862 177a 123a 28a

Tall grass 854 81a 56a 13a

Broadleaf plants/small insects 1048 100a 69a 16a

Fruits, pods, and large insects 116 11a 8a 2a

Seeds (granivores) 116 2a 2a 0.35
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

51

3.2475

(3 / 7)

Short grass 2049 195a 135a 31a

Tall grass 939 89a 62a 14a

Broadleaf plants/small insects 1152 109a 76 17a

Fruits, pods, and large insects 128 12a 8a 2a

Seeds (granivores) 128 3a 2a 0.38

Potato

SLN

(ID,OR,WA)

5

(4 / 7)

Short grass 3946 375a 260a 59a

Tall grass 1808 172a 119a 27a

Broadleaf plants/small insects 2220 211a 146a 33a

Fruits, pods, and large insects 247 23a 16a 4a

Seeds (granivores) 247 5a 4a 0.74

Turf

SLN (CA, OR,

WA)

43.56

(2 / 7)

Short grass 19555 1858a 1291a 293a

Tall grass 8963 851a 592a 134a

Broadleaf plants/small insects 11000 1045a 726a 165a

Fruits, pods, and large insects 1222 116a 81a 18a

Seeds (granivores) 1222 26a 18a 4a

a

 exceeds chronic risk level of concern (RQ $1.0)

Nontarget Aquatic Animals

Surface water concentrations resulting from PCNB application 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 endpoints (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 were 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 major 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’s
52

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. Estuarine/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 invertebrates 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 LC50 of 100 μg/L and chronic NOEC of 13 μg/L and an acute Daphnia magna

EC50 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

LC50 = 100 :g/L

Freshwater

Invertebrateb

LC50 = 770 :g/L

Freshwater Fish a

NOEC = 13 :g/L

Freshwater

Invertebrateb

NOEC = 18 :g/L

Cole crops

30 (1)

84.1

56.1

0.84c

–

0.11d.

–

--

4.3 f

–

3.1 f

Cotton

2.0 (1)

27.8

20.0

0.28d

–

0.04

–

–

1.5 f

–

1.1 f

Peanuts

10 (1)

97.4

45.9

0.97c

–

0.13d

–

–

3.5 f

–

2.6 f

Potatoes

25 (1)

22.0

10.9

0.22d

–

0.03

–

–

0.8 

–

0.6 

Turf

32.67 (2)

258.6

106.1

2.6c

–

0.34d

–

--

8.2 f

--

5.9 f

a

 Rainbow 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/marine animals exposed to PCNB based on a sheepshead

minnow acute LC50 of 7900 μg/L and a mysid shrimp LC50 of 12 μg/L .

Crop Application Rate (# of

apps)

EECs Acute Risk Quotients

Peak

(:g/L)

Estuarine/marine Fisha

LC50 = 7900 :g/L

Estuarine/marine

Invertebrateb

LC50 = 12 :g/L

Cole crops

30 (1) 84.1 0.01 7.0c

Cotton

2.0 (1) 27.8 <0.01 2.3c

Peanuts

10 (1) 97.4 0.01 8.1c

Potatoes

25 (1) 22.0 <0.01 1.8c

Turf

32.67 (2) 258.6 0.03 22c

a

 Sheepshead 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 exceedances 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 risk quotients for PCNB based on three methods of

estimating exposure based on a mallard duck acute oral LD50 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 1a

EEC

mg ai./ft2

Acute RQ

Method 2b

EEC

mg/kg

seed

Chronic

RQc

Barley 296 <0.19d 1.22 <0.04 1171 2.0e

Bean 119 <0.07 0.78 <0.02 469 0.78

Corn 119 <0.07 0.12 <0.01 469 0.78

Cotton 573 <0.36d 0.43 <0.01 2265 3.8e

Oats 435 <0.27d 2.29 <0.07 1718 2.9e

Peas 237 <0.15d 1.76 <0.06 937 1.6e

Peanuts 138 <0.09 0.77 <0.02 547 0.91

Rice 352 <0.22d 2.32 <0.07 1390 2.3e

Sorghum 69 <0.04 0.02 <0.01 273 0.46

Soybeans 237 <0.15d 0.98 <0.03 937 1.6e

Sugar Beets 425 <0.27d 0.14 <0.01 1679 2.8e

Wheat 119 <0.07 0.66 <0.02 469 0.78

a

 Acute RQ Method 1 = mg kg-1 day-1 / LD50 b

 Acute RQ Method 2 = mg ft2 / LD50 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 concern
55

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

LD50 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 LD50 >5050 mg kg-1 and a chronic NOAEC of 200 mg kg-1

of diet.

Crop

EEC

mg

a.i./day

Acute RQ

Method 1a

EEC

mg ai./ft2

Acute RQ

Method 2b

EEC

mg/kg

seed

Chronic 

RQc

Method 3

Barley 172 <0.02 1.22 <0.01 1171 5.9d

Bean 69 <0.01 0.78 <0.01 469 2.3d

Corn 69 <0.01 0.12 <0.01 469 2.3d

Cotton 332 <0.04 0.43 <0.01 2265 11d

Oats 252 <0.03 2.29 <0.02 1718 8.6d

Peas 137 <0.02 1.76 <0.01 937 4.7d

Peanuts 80 <0.01 0.77 <0.01 547 2.7d

Rice 204 <0.02 2.32 <0.01 1390 7.0d

Sorghum 40 <0.01 0.02 <0.01 273 1.4d

Soybeans 137 <0.02 0.98 <0.01 937 4.7d

Sugar Beets 246 <0.03 0.14 <0.01 1679 8.4d

Wheat 69 <0.01 0.66 <0.01 469 2.3d

a

 Acute RQ Method 1 = mg kg-1 day-1 / LD50 b

 Acute RQ Method 2 = mg ft2 / LD50 c

 Chronic RQ = mg kg-1 seed / NOAEC d

 Exceeds chronic risk (RQ $ 1.0) level of concern
56

Risk Discussion

Based on a national, deterministic screening-level 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 invertebrates) 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 effects 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 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. Additionally, chronic 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 the 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 limited number of major agricultural uses and surrogate

species toxicity data. The environmental exposure assessment is based on those uses considered

representative of maximum application rates in terms 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 use nationally. This ecological risk assessment does not

take into account atmospheric transport in estimating 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 determined for aquatic ecological exposure assessment do

attempt to account for total residues of PCNB, i.e., pentachloroaniline (PCA), pentachlorothioanisole (PCTA),

pentachlorobenzene (PCB), pentachlorophenol (PCP), pentachlorothioanisole sulfoxide (PCTASO),

pentachlorothioanisole sulfone (PCTASO2) 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 exist almost exclusively in the vapor phase in the

atmosphere. The estimated photo-oxidation half-life for PCNB in the vapor phase is estimated to be 2,200
57

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 (LD50>2,250 mg/kg bw) and

subacute dietary (LC50>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 (LD50>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

(LD50>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 sufficiently 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 exceeded 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 LOC’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 reductions in the number of eggs laid,

number of hatchlings, and number of viable embryos are 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 cabbage, 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 affect both the liver and thyroid leading to hypertrophy

in both organs and follicular cell hyperplasia in the 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, soil 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 standard 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 exceeded 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 risk levels of concern are exceeded are exceeded for

freshwater invertebrates. The high RQ values for turf reflect the relatively high maximum application rate

(2 applications of 32.6 lbs a.i./acre) used.

For estuarine/marine fish, the LC50 value (7.9 mg/L) exceeds the solubility of PCNB in water (0.44

ppm at 25o

C) and no acute risk LOC’s are exceeded; however, estuarine/marine invertebrates were the most

sensitive nontarget animals tested (mysid shrimp LC50 = 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 calculated; however, if the acute-to-chronic ratio (ACR =

acute EC50/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, respectively, 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 invertebrates 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 pentachlorobenzene increases the toxicity of the compound by an order of

magnitude.

Although not frequently detected in NAWQA monitoring 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 that PCNB bioconcentrates and that sediment-dwelling

invertebrates and bottom-feeding fish contain measurable 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 communities 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

EC50-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 biological effects of chemicals present in the water

phase. However, aquatic organisms might also be exposed to organic chemicals that are deposited onto or

assimilated into their food substrates. Thus, dietary uptake is an additional route of exposure that should be

considered in the toxicity assessment of chemicals such as PCNB that have a tendency to
59

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 degradate and contaminate pentachlorobenzene (PCB) in the

Detroit River, PCB was highest for benthic invertebrates with concentrations ranging from 5 to greater than

100 μg/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 important 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 coefficient values suggest that PCNB and its metabolites will

bioconcentrate in aquatic organisms. Dietary absorption 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 chloronitrobenzenes 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 incidents involving freshwater fish kills that are associated with

PCP with as many as 271,000 fish dead; however, the incident reports are not detailed enough to determine

the source of the PCP. It is likely that PCP at a sufficient 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 formation of PCP as a degradate of PCNB and the relative

contribution from other sources of this compound. 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.

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. However, because of the chemical’s persistence, chronic

risk of reduced reproductive success and growth may occur as chronic risk levels of concern are exceeded

for birds. Even though chronic risk LOC’s are exceeded for mammals, there is uncertainty regarding the

relevancy of the measurement endpoints (hepatic/thyroidal hyperplasia) to chronic risk assessment endpoints

of impaired reproduction, growth and/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/growth 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 PCTASO2

Dermal Uptake Gill Uptake Ingestion 

Bioconcentration Biomagnification

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 PCTASO2

Dermal Uptake Gill Uptake Ingestion 

Bioconcentration Biomagnification

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 PCTASO2

Dermal Uptake Gill Uptake Ingestion 

Bioconcentration Biomagnification

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, PCNB, its major degradate PCTA, and its potential

degradate PCP have the ability to bind estrogen receptors 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 organochlorine insecticide dieldrin. Additionally,

OPP is uncertain whether the reproductive effects in birds 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 effect 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 recommendation that the Program include evaluations of

potential effects in wildlife. For pesticide chemicals, EPA will use FIFRA and, to the extent that effects in

wildlife may help determine whether a substance may have 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 appropriate
61

screening and/or testing protocols being considered under the Agency’s EDSP have been developed, PCNB

may be subjected to additional screening and/or testing 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 sufficient data to resolve certain aspects of the likely

exposure and or effects resulting from the use of PCNB. 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 generate EDWC’s and EEC’s is unable 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 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. 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 undergoes 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 are not available and therefore terrestrial exposure

assessments relied on the default value of 35 days. While volatility may substantially reduce the amount of

PCNB residues following foliar applications, there were no data submitted to determine 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 receptors. Additionally, several of the chronic effects

(reduced number of eggs produced, thyroid hyperplasia) noted across taxonomic groups are consistent with

endpoints that OPP uses to identify chemicals with a potential 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-dwelling 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 with the likely persistence of the compound, there is a

potential for chronic exposure in estuarine environments.

Data on the toxicity of PCNB to terrestrial, semi-aquatic, 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 assessment 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 screening-level endangered species risk assessment. The Agency

will reassess the potential risk of PCNB use to endangered species using the new process at a later date and

consult as appropriate with the Fish and Wildlife Service and National Marine Fisheries Service at that time.

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quail. Project No. 88 QR 30. Prepared by Bio-Life Associates, Ltd., Neilsville, WI. Submitted by AMVAC

Chemical Corporation, Los Angeles, CA. MRID: 413211-01.

Pedersen C. A. and D. W. Fletcher. 1989. PCNB technical: toxicity and reproduction study in Mallard

ducks. Project No. 88 DR 27. Prepared by Bio-Life Associates, Ltd., Neilsville, WI. Submitted by

AMVAC Chemical Corporation, Los Angeles, CA. MRID: 413212-01.

Rostad, C.E., W.E. Pereira and T.J. Leiker. 1994. Distribution and transport of selected anthropogenic

organic compounds associated with Mississippi River suspended sediment (USA), May/June 1988. Archives

of Environ. Contam. and Tox. 36:248–255.

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.

Russell RW, Gobas FAPC, and GD Haffner. 1999. Role of chemical and ecological factors in trophic

transfer of organic chemicals in aquatic food webs. Environmental Toxicology and Chemistry 18: 1250 -

1257.

Sabljiƒ, A., H. Güsten, H. Verhaar and J. Hermen. 1995. QSAR modelling of soil sorption. Improvements

and systematics of log KOC vs. log KOW correlations. Chemosphere 31:4489-4514.

Schauerte, W., J.P. Lay, W. Klein and F. Korte. 1982. Long-term fate of organochlorine xenobiotics in

aquatic ecosystems. Ecotoxicol. and Environ. Safety 6:560-569.

Surprenant, D. C. 1988. Acute toxicity of pentachloronitrobenzene to Mysid shrimp (Mysidopsis bahia)

under flow-through conditions. Report No. 88-7-2773. Prepared by Springborn Life Sciences, Inc.,

Wareham, MA. Submitted by Uniroyal Chemical Company, Inc., Bethany, CT. MRID: 408829-01.
66

Surprenant, D. C. 1988. Acute toxicity of pentachloronitrobenzene to Sheepshead minnow (Cyprinodon

variegatus) under flow-through conditions. Report No. 88-7-2724. Prepared by Springborn Life Sciences,

Inc., Wareham, MA. Submitted by Uniroyal Chemical Company, Inc., Bethany, CT. MRID: 408323-02.

Surprenant, D. C. 1988. Acute toxicity of pentachloronitrobenzene technical to Eastern oysters (Crassostrea

virginica) under flow-through conditions. Report No. 88-4-2701. Prepared by Springborn Life Sciences,

Inc., Wareham, MA. Submitted by Uniroyal Chemical Company, Inc., Bethany, CT. MRID: 408323-03.

Surprenant, D. C. 1988. Acute toxicity of Terraclor 2EC to Bluegill (Lepomis macrochirus) under flowthrough conditions. Prepared by Springborn Life Sciences, Inc., Wareham, MA. Submitted by Uniroyal

Chemical Company, Inc., Bethany, CT. MRID: 406503-02.

Surprenant, D. C. 1988. Acute toxicity of pentachloronitrobenzene technical to Rainbow trout

(Oncorhynchus mykiss) under flow-through conditions. Study No. 88-4-2698. Prepared by Springborn Life

Sciences, Inc., Wareham, MA. Submitted by Uniroyal Chemical Company, Inc., Bethany, CT. MRID:

406180-05.

Surprenant, D. C. 1988. Acute toxicity of pentachloronitrobenzene technical to Bluegill (Lepomis

macrochirus) under flow-through conditions. Study No. 88-5-2725. Prepared by Springborn Life Sciences,

Inc., Wareham, MA. Submitted by Uniroyal Chemical Company, Inc., Bethany, CT. MRID: 406180-04.

Surprenant, D. C. 1991 (supplemental). Acute toxicity of pentachloronitrobenzene technical to Eastern

oysters (Crassostrea virginica) under flow-through conditions. Report No. 88-4-2701. Prepared by

Springborn Life Sciences, Inc., Wareham, MA. Submitted by Uniroyal Chemical Company, Inc., Bethany,

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flow-through conditions. Study No. 88-5-2727. Prepared by Springborn Life Sciences, Inc., Wareham, MA.

Submitted by Uniroyal Chemical Company, Inc., Bethany, CT. MRID: 406503-01.

Surprenant, D. C. 1988. Acute toxicity of pentachloronitrobenzene (PCNB) to Eastern oysters (Crassostrea

virginica) under flow-through conditions. Report No. 88-6-2760. Prepared by Springborn Life Sciences,

Inc., Wareham, MA. Submitted by Uniroyal Chemical Company, Inc., Bethany, CT. MRID: 408829-02.

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bahia) under flow-through conditions. Report No. 88-6-2748. Prepared by Springborn Life Sciences, Inc.,

Wareham, MA. Submitted by Uniroyal Chemical Company, Inc., Bethany, CT. MRID: 408323-01.

Surprenant, D. C. 1988. The toxicity of pentachloronitrobenzene technical to Fathead minnow (Pimephales

promelas) embryos and larvae. Report No. 88-9-2803. Prepared by Springborn Life Sciences, Inc.,

Wareham, MA. Submitted by Uniroyal Chemical Company, Inc., Bethany, CT. MRID: 408840-01.

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67

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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 other interested parties on July 17, 2001. Utilizing use

and usage information supplied by the registrants for that meeting and subsequent research inside and outside

EPA, I have drafted the Agency’s record of common understanding on the uses to be included in the human

health and environmental risk assessments for PCNB. This record also covers responses to specific questions

from the team.

I have asked the registrants to review this document 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 (please 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 registrations with soil and seed treatment 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, tobacco), mushrooms, turf, and ornamentals. It is applied

both to soil and seeds.
69

The following food/feed uses of PCNB will be supported through reregistration (predominant uses in

bold):

Amvac: beans (dry, snap [bush, pole], succulent), cole crops (broccoli, Chinese broccoli, Brussels sprouts,

cabbage, Chinese cabbage, cauliflower, collards, kale, mustard greens), cotton, garlic, peanut, peppers,

potatoes, tomatoes; seed treatments (barley, beans, corn, cotton, oats, peas, safflower, sorghum, soybeans,

sugar beets, rice, wheat). Also seed treatments (Amvac sells technical to Gustafson): barley beans, corn,

cotton, oats, peanuts, peas, rice, safflower, 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 crops, cotton, garlic, hot pepper, peanut, peppers, potatoes,

tomatoes

Complete list of seed treatments sites: barley, beans, corn, cotton, oats, peas, peanut, rice, safflower, sorghum,

soybeans, sugar beets, rice, wheat

The following non-food uses of PCNB will be supported through reregistration (predominant uses in

bold):

Amvac: ornamental plants (bedding, cut flowers, 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)
70

Application 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

barley bean EC

FGWPWSP

ECFGWSPWP

EC 

cole crop EC

FGWSPWP

ECFGWSPWP

ECFGWSPWP

corn D*

F*

cotton EC EC

FGWSPWP

D*F**

garlic EC

FG?WPWSP

ECFGWPWSP

home gardenveggies

G G
Site

At cultivation

Band

Band row

Broadcast

Chemigation

Clove treatment

In-furrow

Row or row

drench

Seed treatment

71

hot pepper EC

FGWSPWP

pea not specifiedpeanut F

GWPWSP

ECFGWPWSP

ECWP

ECFGWSPWP

D***F*?

pepper EC

FGWPWSP

oats not specifiedpotato F EC

G

ECF

ECG

rice not specifiedsafflower not specifiedsorghum not specifiedsoybean D*

F**

sugar beet not specified
Site

At cultivation

Band

Band row

Broadcast

Chemigation

Clove treatment

In-furrow

Row or row

drench

Seed treatment

72

tomato EC

FGWPWSP

wheat F

L

For seed treatments:* on farm; ** commercial; *** both
73

Table 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

azaleas, camellias F

GWPWSP

G not specified

bedding plants F

G

FWP

calendula, larkspur, snapdragon,sweetpea

FGWPWSP

cut flowers Fgladiola F

GWP

FGWPWSP

herbaceous, woody plants

GF

FGWPWSP

bulbs F

GWPWSP

FGWPWSP

FGWPWSP

FGWPWSP
Site

Band

Band row

Broadcast

Dip, direct spray

Drench

In-furrow

Row or row

drench

74

lily F

GWPWSP

FGWPWSP

F

pine F

GWPWSP

roses F

GWPWSP

tropical foliage plants F

G

FGWPWSP

turf grass EC

FGWPWSP

dichondra F

GWPWSP
75

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/surface 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 and transplant applications of PCNB

Application Rate lbs.ai/A # applications 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 0.0525
78

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 various 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, depending 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. Higher 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 than the 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 in Tables 1 and 2. Amvac: Chemigation is a labeled application

method for peanuts and potatoes. Amvac states that <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 treated at 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 applicator 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 field-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 turf 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 Uniroyal’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 are 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 dip, where rates are reported in lbs of formulation per

100 gallons of water, please 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 treated 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; amounts 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 use
83

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 respirators (TC-21C) for outdoor exposure, organic vapor

removing cartridges with a prefilter approved for pesticides (TC-23C) or canisters ((TC14G) for indoor

exposures. Chemical resistant apron required in addition 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 disulfoton 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 chemical 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 with 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 annual 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 applied 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 plant 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 associated 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-specific monitoring data available for worker or dietary exposure, or

ground-, surface, or drinking water?

Not to Amvac’s knowledge. Uniroyal: USDA’s Pesticide 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-tested, is used on a wide range of crops, is not prone

to problems with resistance. For turf, very few products 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 control 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 development especially when used in combination with the newer

fungicides.

Potential alternatives as reported by the registrants are detailed in Tables 13 and 14.

Table 13. Alternative pesticide treatments for 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 X
87

Table 14. Alternative pesticide treatments for 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, Amvac Chemical, and Gustafson LLC were all asked to

review the memo for accuracy with respect to their products and to provide updated and missing information.

The revisions in this addendum are based on comments received from Crompton/Uniroyal on the memo and

in subsequent communications. Gustafson provided one general comment, that the memo correctly

characterized the use of its registrations. Amvac Chemical 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 Crompton/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 available 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 PCNB 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, beans, 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 incorporation, and that only its flowable formulation (not granular or

wettable powder formulations) may be applied to mushroom houses.

Although PCNB is mostly applied once per season, multiple 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 beneath bushes and in the plant bed 

Beans (for white mold) Amvac first application 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 generally specified but not separately for

repeat applications; important to water-in

Ornamental bedding plants Uniroyal

Amvac

one repeat application 4-6 weeks after 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 after 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 directed to apply the product 3 times as a granular or liquid

spray in a 12 inch band centered over the row after planting. 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 applicator] could apply the products at this timing without

contacting the plants, unless [the registrant] specified use of drop tubes or nozzles that 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 planting” heading, but obviously would be after planting

and applied in a band over the row. This would 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 applications 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 planting.” 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 repeat
91

application although the initial treatment is a soil drench. TX900010 (5481-212) allows repeat application

on peanuts at 3 gal/A of product through overhead sprinkler irrigation 30 days after initial treatment of 2

lbs/A. TX920024 (5481-279) allows repeat application on peanuts at 5 lbs/A of product through overhead

sprinkler irrigation 30 days after initial treatment of 8 lbs/A. ID000008, NV000005, OR000019, and

WA000030 (5481-472) allow repeat applications 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 application 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 that 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 applications to cut flowers with a spray or dip.

Uniroyal has also provided additional information 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)
92
93
94
95
96
97
98

APPENDIX A3. QUANTITATIVE USAGE ANALYSIS FOR PCNBCase Number: 0128 Date: 10/12/2001 Analyst: Tim Kiely Data PC Code: 56502 Original QUA date: 01/11/99 QUA last edited: 10/12/2001 Filen

Based on available pesticide survey usage information for the years of 1990 through 2000, an annual estimate of PCN

approximately 1,825,000 pounds of active ingredient (a.i.) applied to 794,000 acres. PCNB is a fungicide with its largest markingredient allocated to turf (49%) and cotton (27%). The crops with the highest percentage of their total U.S. planted acres trea

(13%), cotton (5%), and potatoes (3%). No other crop has more than 2% of their acreage treated with PCNB. Please see Tab

Table 1. Estimates of PCNB Usage by site.

Site Acres 

Grown

(000)

Acres Treated

(000)

% of Crop

Treated

Pounds AI

Applied 

(000)

Average Application Rate 

Wtd

 Avg

Est

Max

Wtd

 Avg

Est

Max

Wtd

 Avg

Est

Max

lb ai/ 

acre/yr

#appl

/ yr

lb ai

A/app

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 Cole Crops /1 303 3 5 1% 2% 16 32 6.1 1.0 6.1 
Site Acres 

Grown

(000)

Acres Treated

(000)

% of Crop

Treated

Pounds AI

Applied 

(000)

Average Application Rate 

Wtd

 Avg

Est

Max

Wtd

 Avg

Est

Max

Wtd

 Avg

Est

Max

lb ai/ 

acre/yr

#appl

/ yr

lb ai

A/app

99

- Mustard, greens 9 0* 0* 0% 0% 0* 0* -- -- -- - Broccoli 126 1 2 0% 1% 2 4 3.6 1.0 3.6 - Brussels Sprouts 4 0 1 13% 17% 10 20 22.2 1.5 14.8 - Cabbage 82 1 1 1% 2% 1 1 0.7 1.0 0.7 - Chinese Cabbage 12 -- -- -- -- -- -- -- -- -- - Cauliflower 53 1 2 2% 3% 3 7 3.7 1.0 3.7 - 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 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 
Site Acres 

Grown

(000)

Acres Treated

(000)

% of Crop

Treated

Pounds AI

Applied 

(000)

Average Application Rate 

Wtd

 Avg

Est

Max

Wtd

 Avg

Est

Max

Wtd

 Avg

Est

Max

lb ai/ 

acre/yr

#appl

/ yr

lb ai

A/app

100

Beans/Peas, Dry 2,237 0 1 0% 0% 0 1 0.8 1.0 0.8 Beans/Peas, Green 708 15 20 2% 3% 15 20 1.0 1.1 0.9 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 Wheat 71,464 1 3 0% 0% 0 1 0.5 1.0 0.5 Soybeans 66,533 4 18 0% 0% 6 25 1.5 1.3 1.1 Cotton 13,232 700 1,200 5% 9% 490 840 0.7 1.0 0.7 Peanuts 1,515 10 23 1% 2% 17 36 1.7 1.2 1.4 Sugar Beets 1,434 0 2 0% 0% 0 1 1.0 1.0 1.0 Tobacco 712 10 22 1% 3% 9 20 0.9 1.0 0.9 Clover -- -- -- -- -- -- -- -- -- -- Ginseng -- -- -- -- -- -- -- -- -- -- 
Site Acres 

Grown

(000)

Acres Treated

(000)

% of Crop

Treated

Pounds AI

Applied 

(000)

Average Application Rate 

Wtd

 Avg

Est

Max

Wtd

 Avg

Est

Max

Wtd

 Avg

Est

Max

lb ai/ 

acre/yr

#appl

/ yr

lb ai

A/app

101

Coffee -- -- -- -- -- -- -- -- -- -- Turf /3 -- -- -- -- -- 900 1,150 -- -- -- Ornamental Plants /4 -- -- -- -- -- 45 70 -- -- -- Seed Treatment /5 -- -- -- -- -- 125 200 -- -- -- Total 794 1,082 1,825 2,263

NOTES ON TABLE DATA

- Usage data primarily covers 1990 - 2000.- Wtd Avg = Weighted average--the most recent years and 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 agree because they are displayed as rounded to the nearest 1000 for acres treated or lb. a.i. (ther

percentage point for % of crop treated (Therefore 0% = < 0.5%).- 0* = Available EPA sources indicate that no usage is observed in the reported data for this site, which implies that there is little or no usage.- A double dash (--) indicates that information on this site is 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 Service Chemical Use Reports, California Department of Pesticide Regulation Pesticide Usand Agricultural Policy pesticide use database.
102
103

APPENDIX B. ENVIRONMENTAL FATE DATA

Abiotic Degradation

Hydrolysis

Pentachloronitrobenzene (PCNB) is stable to hydrolysis 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 provide adequate data for the risk assessment. 

Aqueous Photolysis

PCNB is rapidly photodegraded in water under favorable light conditions. Two separate guideline

studies were submitted. In one study, [U-14C]PCNB, at 0.075 ppm, photodegraded with a half-life of

approximately 27 hours (corrected for continuous irradiation 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 compound tentatively identified. In the second study, [U- 14C]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 acceptable and provide useful data for the risk assessment.

The identification of the photoproducts of PCNB would provide additional useful information for future risk

assessments.

Soil Photolysis

PCNB photodegrades slowly on soil. Two separate guideline studies were submitted. In the first

study, [14C]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 despite additional analysis. The half-life

reported in the study is of questionable value, as it was extrapolated 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, [14C]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 (PCTASO2). 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 accounted 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, [14C]PCNB, at 10 ppm, dissipated (degradation plus 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 DT50:

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 CO2) 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 (PCTASO2; 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, [14C]PCNB, at 10.5 ppm, dissipated (degradation plus volatilization) with a halflife of 77 days in aerobic sandy loam soil that was incubated in the dark at 25 °C for 1 year (MRID’s

41384501, 41713202, 42112801). By the end of the study, volatiles (mainly PCNB, with some PCA and

minimal CO2) 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 the 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 degradate 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, and in response to a decision made by the MARC

committee, the half-lives were recalculated using concentration data for the parent compound plus the

degradate PCA. The recalculated aerobic soil metabolism half-lives for the parent/PCA combination are 489

days (r2

 = 0.54; MRID 42911902) and 1012 days (r2 = 0.53; MRID’s 41384501, 41713202, 42112801); these

are the values that will be used to determine estimated drinking 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 assessment, the compound was not detected in either of the aerobic soil

metabolism studies. For the determination of the estimated 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, PCTASO2 and/or HCB). The

recalculated aerobic soil metabolism half-lives for total residues are 983 days (r2

 = 0.50; MRID 42911902)

and 1052 days (r2

 = 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. However, the major degradate, PCA, appears to be stable

to further degradation.

In one study, [14C]PCNB, at 25 ppm, dissipated (degradation plus volatilization) with an observed

DT50 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 after being incubated aerobically for 30 days (MRID’s 41203602,

42094401). Post-flooding sampling intervals were inadequate 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 soil 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 maximum 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 majority of the volatiles at all intervals, with PCB

and HCB detected only at 30 days and in small amounts (2.7% and 1.9% of total volatiles, respectively)

relative to PCNB and PCA. This study was classified 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 with 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 metabolism studies rather than from additional anaerobic

soil metabolism studies.

 

In the second study, [14C]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-flooding 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% were 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 volatiles. PCNB was present in the flooded soil system at

71.4% of the applied immediately post-flooding and decreased 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 radioactivity 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 degradation 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, and in response to a decision made by the MARC

committee, the half-lives were recalculated using concentration data for the parent compound plus the

degradate PCA. The recalculated anaerobic soil metabolism half-life for the parent/PCA combination is 410

days (r2

 = 0.92; MRID’s 41384301, 41686001, 41713203, 42112802); this is the source data value that will

be used to determine estimated drinking water concentrations (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 individual 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 assessment, the half-lives were recalculated using “total

residues” (defined here as including only the following compounds of interest: PCNB, PCA, PCTA, PCB,

PCP, PCTASO, PCTASO2 and/or HCB). The recalculated anaerobic soil metabolism half-life for total

residues is 334 days (r2

 = 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 (Kd) 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 matter, and to be immobile in most others; thus, it is also

generally expected to bind to aquatic sediments as well as to organic matter in the water column. Based on

soil adsorption coefficient (Kd) values determined using Freundlich adsorption isotherms with batch

equilibrium study data, the major degradates pentachloroaniline (PCA) and pentachlorothioanisole (PCTA)

are expected to be immobile in soil. Three separate 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 Koc values were 1588-17508. Desorption, following
107

overnight equilibration, was 6.31-94%. The desorption K values were 0.49-1.11 mL/g; desorption Koc 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 studied 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 adsorption K values were 64-1750 mL/g and adsorption Koc

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 studied were acidic, with pH values of 4.7, 4.8, 5.0 and 5.7.

Table B1. Freundlich adsorption and desorption constants for PCNB in eight soils.

Soil type (% organic

carbon; pH)

Adsorption Desorption

K (mL/g) 1/n r2 Koc K (mL/g) 1/n r2 Koc

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 NR3 12356 ————

sandy loam (0.87%,

pH 4.8)2

64.1 1.15 NR3 7368 ————

silt loam (1.45%, pH

4.7)2

101 0.94 NR3 6966 ————

silt loam (1.16%, pH

5.0)2

1750 0.67 NR3 150862 ————

1

Data obtained from MRID 41648201. 2Data obtained from MRID 00114168; study did not address desorption and adsorption values will not be used

in the risk assessment due to experimental methodology shortcomings. 3

NR = not reported.

A third study (MRID 400114181) conducted using leaching columns was found to be supplemental

and provides limited useful data for the risk assessment. [14C]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 leaching. 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% and 0.46% of the applied, respectively, in the top 5-cm

layer of the sandy loam soil column. [14C]PCNB was not detected in the leachate from any of the columns.

The study was sound to be supplemental 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 concentrations ranging from 0.05 to 0.20 μg/mL and maintained in
108

darkness at 22.5 oC for 24 hours (MRID 43500502). The respective adsorption K values were 37, 78, 39,

and 117; corresponding Koc 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 silt loam soil, and 160 for the silty clay loam soil;

corresponding Koc 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 concentrations 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 Koc values were 18610, 19395, 45662, and 37267. Desorption K values were 202

for the sand soil, 262 for the sandy loam soil, 244 for the silt loam soil, and 630 for the silty clay loam soil;

corresponding Koc 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/cm2

/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/m3

.

At 7 days posttreatment, volatilized PCNB was a total of 1556-1650 μg (approximately 80% of the applied);

no other volatile compounds were detected. The study 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 which had been previously moistened to 75% of field

capacity. The maximum volatilization rates were 4.31 x 10-3 μg/cm2

/hr for airflow at 50 mL/min and 6.08

x 10-3 μg/cm2

/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 provides 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 in Mississippi; 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 filters 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 occurred 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 representative 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 field 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 information and half-life and leaching results are presented

in Table B2. The half-lives (272 and 459 days) determined in two of the bare ground plot studies were of

questionable value due to high data variability. In the third bare ground plot (under treatment conditions for

peanuts), the calculated half-life of PCNB was 57 days, although the (observed) DT50 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 versus 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 PCA, 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 submitted. 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 below 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 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. 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 estimated half-life of 459 days (excluding day 269 data; r2

 =

0.14; MRID 43887402). However, the data exhibited high temporal and inter-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 PCTA was 0.73 ppm. The contaminant HCB was 0.03

ppm on days 0-30, was <LOQ on days 59-209, and was 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 analytical method utilized did not allow for the detection

of the potential degradate PCP. This study is classified 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. However, the study does provide some useful information on

leaching and general persistence 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) DT50 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, in part, to use of the granular formulation. The

degradate pentachloroaniline (PCA) was present at a maximum 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 pentachlorobenzene (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 application. Total PCNB residues (parent plus PCA and PCTA)

dissipated with a half-life of 436 days. PCNB was detected 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 detected 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 DT50 (observed) for dissipation in soil was between 30 and 60 days, while the DT50 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 the 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 DT50 values (observed)

indicated that the calculated half-lives overestimated the 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 California 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 provides 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 concentration was 4.3 ppm immediately posttreatment, increased to

6.9 ppm at 1 day posttreatment, was 2.7 ppm at 28 days, 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 posttreatment. 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, PCNB 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 detected at any depth below 6 inches. 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.
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

DT50) 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 t1/2 = 272 (r2

= 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 t1/2 = 459 (r2

= 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 t1/2 = 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 t1/2 = 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 DT50 =

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 t1/2 = 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 t1/2 = 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 t1/2 = 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 validity due to high data variability. 2PCA = pentachloroaniline; PCTA = pentachlorothioanisole; PCB =

pentachlorobenzene; PCP = pentachlorophenol; PCTASO = pentachlorothioanisole sulfoxide; TCTASOO = tetrachlorothioanisole sulfone. 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. 4The compounds, where noted, were detected at the 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 residues accumulated in bluegill sunfish exposed to

[

14C]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 [14C]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 [14C]residues were eliminated from the fish

tissues. Residues in fish tissue were not characterized in the initial study. Thus, an additional study was

conducted to identify residues that accumulated in the tissues. In the ancillary study, [14C]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 [14C]residues in the edible and nonedible fish tissues totaled 170-200 and 1100-1200 μg/kg, respectively

(MRID 43179301). Three [14C]compounds isolated from the fish tissues were identified as N-acetyl Spentachlorophenyl cystine (the cystinyl conjugate of PCNB), PCTA and PCTASO. One additional

[

14C]compound, Metabolite 8, was isolated from the fish tissues 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 [14C]residues totaled 14-19.4% of applied in the edible 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 together the two studies provide adequate data for the risk

assessment. 

In the second bioaccumulation in fish study, uncharacterized PCNB residues accumulated in bluegill

sunfish exposed to [14C]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 determined in the first study, this study was considered

invalid upon review due to problems achieving a constant aqueous exposure concentration. Maximum mean

concentrations of total [14C]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 the 21-day depuration period, 78% of the accumulated

[

14C]residues were eliminated from the edible and viscera tissues. Residues in fish tissue were not

characterized in the initial study. Thus, an additional study was conducted to identify residues that

accumulated in the tissues. For both edible and viscera tissues, the predominant compound detected in the

organic extract of the tissues was the degradate PCTA (MRID 41951701). These studies (taken together) are

classified as supplemental and provide some useful information for the risk assessment.
115

NO2

Cl

Cl

Cl

Cl

Cl

NH2

Cl

Cl

Cl

Cl

Cl

SCH3

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 608-93-5
Chemical Name and Structure

116

SCH3

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 87-86-5
Chemical 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 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 Screening 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 are 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.

 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
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 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 Kd 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

(DT50'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 acceptable 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 for plots with incorporated PCNB. The major degradates of PCNB in the

environment are PCA and pentachlorothioanisole (PCTA); minor degradates are pentachlorothioanisole

sulfoxide (PCTASO), pentachlorothioanisole sulfone (PCTASO2), 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 drinking 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/application in two applications (total application rate

of 65.34 lb a.i./A. Note that 440 ppb is the aqueous solubility limit of PCNB at 25 o

C. 2Groundwater 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 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 applications of PCNB.

Seed treatment usage rates were considered (after conversion 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 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
120

(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 with 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 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 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 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 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 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 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 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 PCNB 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 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 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 the 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 application

scenario. The EDWC’s for parent only were 440 ppb for both acute and chronic exposures, indicating that
121

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 (without including 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. 
122

Table 2. FIRST (v1.0) input parameter values and 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 (Kd; mL/g) 15.5 (MRID 41648201; lowest non-sand Kd)

Aerobic Soil Metabolism Half-life (days) t1/2 = 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) t1/2 = 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 Drinking Water Concentrations for

surface water)

Acute Concentration (ppb): 4402 (all crops)

Chronic Concentration (ppb): 

turf: 440.0

peanuts: 183.6

cole crops: 301.4

potatoes: 251.2

bulb crops: 440.0; 328.63

1

For the purposes of the drinking water assessment, half-lives were recalculated to account for the parent plus the degradate PCA. The aerobic soil

metabolism half-life used in the models represents the 90th percentile 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 multiplying 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. 3Because FIRST does not allow directly for incorporation of a non-granular

formulation (as is done for this usage), the EDWC was also determined for this crop (2nd 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.
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) t1/2 = 750.5 days (parent plus

 PCA; average of two values)1

Organic Carbon Partition Coefficient

(Koc)

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: 2.87

cole crops: 4.31

potatoes: 3.59

bulb crops: 30.6

1

For the purposes of the drinking water assessment, half-lives were recalculated to account for the parent plus the degradate PCA, 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.
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 based on PCNB use on beans (dry-type) at 40.84 lb a.i./A/application in a single application . Note that

this application rate is the same as that used for multiple other crops with a soil drench application usage. Note also that 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, 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 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
125

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. 

Pentachlorophenol

It was decided by the 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 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 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 generally 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 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 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” 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 their 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. 
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 which 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 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 PCA 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 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 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-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 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 associated 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, 10th 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. 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. Degradation 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 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/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-chemical property source data for PCNB modeling.

PARAMETER VALUE

 Chemical Name pentachloronitrobenzene

 Molecular Weight 295.3

 Solubility (25 oC) 0.44 mg/L (440 ppb)

 Vapor Pressure (25 oC) 1.13 x 10-4 mmHg

 Hydrolysis Half-life (pH 5, 7, 9; 25 oC) stable (MRID’s 40865301, 40972601)

 Aqueous Photolysis Half-life (pH 7) t1/2 = 2.5 days (MRID’s 42606201, 42606202)

t1/2 = 26.8 hours (MRID 42336201)

 Soil Photolysis Half-life stable (MRID’s 41004801, 41713201)

 Aerobic Soil Metabolism Half-life t1/2 = 77, 189 days (parent only);

t1/2 = 489, 1012 days (parent plus

 PCA)1

t1/2 = 983, 1052 days (total residues)2

(MRID’s 42911902, 41384501, 41713202, 42112801)

 Anaerobic Soil Metabolism Half-life t1/2 = 9 days, <30 (DT50; parent only); 

t1/2 = 210, 410 days (parent plus

 PCA, PCP) 

t1/2 = 268, 334 days (total residues) 

(MRID’s 41203602, 42094401, 41384301, 41686001, 41713202, 42112802)

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

 Soil Partition Coefficient (Kd, mL/g) 7.3, 15.5, 19.1, 210 (MRID 41648201)

1

For the purposes of the drinking water assessment, half-lives were recalculated to account for the parent plus the degradates PCA and PCP, when

monitored and detected. 2

For the purposes of the ecological assessment, half-lives were recalculated to account for total residues, inclusive of the

parent plus the degradates PCA, PCTA, PCB, PCP, PCTASO, PCTASO2, 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, Risk 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 degradate 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 values 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; details 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, the 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 updated 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 recommended by EFED for use in the human health risk

assessment for PCNB are those presented in Table 1. 
132

Table 1. Estimated Drinking Water Concentrations 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 generated using the PRZM/EXAMS model with a foliar/ground spray to turf in

Pennsylvania application 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 turf use acute concentration. However, as this is greater than the aqueous solubility of 440 ppb for PCNB, the solubility limit

should be used instead. 2

Groundwater EDWC’s (Tier I screening level) are based on PCNB use on bulb crops at 213.4 lb a.i./A/application in a

single application.

Reported values represent the maximum concentration 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 parameter 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, most 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 obtained 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 was 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 Applications (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 (Kd; mL/g) 15.5 MRID 41648201; lowest non-sand Kd

Aerobic Soil Metabolism Half-life (days) t1/2 = 1555 days (parent plus PCA) MRID’s 42911902, 41384501,

41713202, 42112801; represents the 90th

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-m3

-mol Product chemistry data

Solubility in Water at 25o

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) t1/2 = 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)

t1/2 =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, 40972601
Parameter 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 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 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 results 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 4401 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 solubility 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, cabbage (cole crop), potatoes and cotton. To simulate

these uses, EFED 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. 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. The human drinking water EDWCs were determined using the

standard index reservoir scenario in which a 172-ha field drains into a 52000 m2

 reservoir and percent

cropped area (PCA) is taken into consideration. The PCA for each of the four crops modeled except turf

is the default value of 0.87; a value of 1.0 is used for 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 15th was 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 pesticide 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 terms 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 15th was 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 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 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 those crops predominantly in the south. An application

date of April 15th was chosen for a pre-plant application to peanuts based on a planting time of April 20th

to May 20th. An application date of April 20th was chosen for a pre-plant application to cotton based on a

May 1st planting 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 incorporation 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 Northwest and the Great Lakes regions. An application

date of May 20th was chosen for a pre-plant application to potatoes based on a planting time of April to

June 10th for 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 Screening 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 are 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 Kd 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 (DT50'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 acceptable 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 for plots with incorporated PCNB. The major

degradates of PCNB in the environment are PCA and pentachlorothioanisole (PCTA); minor

degradates are pentachlorothioanisole sulfoxide (PCTASO), pentachlorothioanisole sulfone

(PCTASO2), 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 drinking 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/application in two applications (total application

rate of 65.34 lb a.i./A. Note that 440 ppb is the aqueous solubility limit of PCNB at 25 o

C. 2Groundwater EDWC’s are based on PCNB use on

bulb crops at 213.4 lb a.i./A/application 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), 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 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 applications of PCNB. Seed treatment usage rates

were considered (after conversion 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 Elegibility 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 with 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 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 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 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 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 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 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 PCNB 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 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

solubility limit of the parent compound at 25 oC. 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 the 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 application 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 (without including 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 and 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 (Kd; mL/g) 15.5 (MRID 41648201; lowest non-sand Kd)

Aerobic Soil Metabolism Half-life (days) t1/2 = 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) t1/2 = 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 Drinking Water Concentrations for

surface water)

Acute Concentration (ppb): 4402 (all crops)

Chronic Concentration (ppb): 

turf: 440.0

peanuts: 183.6

cole crops: 301.4

potatoes: 251.2

bulb crops: 440.0; 328.63

1

For the purposes of the drinking water assessment, half-lives were recalculated to account for the parent plus the degradate PCA. The aerobic

soil metabolism half-life used in the models represents the 90th percentile 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 mulitiplying 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. 3Because FIRST does not allow directly for

incorporation of a non-granular formulation (as is done for this usage), the EDWC was also determined for this crop (2nd 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) t1/2 = 750.5 days (parent plus

 PCA; average of two values)1

Organic Carbon Partition Coefficient

(Koc)

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: 2.87

cole crops: 4.31

potatoes: 3.59

bulb crops: 30.6

1

For the purposes of the drinking water assessment, half-lives were recalculated to account for the parent plus the degradate PCA, 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 beans (dry-type) at 40.84 lb a.i./A/application in a single application . Note

that this application rate is the same as that used for multiple other crops with a soil drench application usage. Note also that 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, 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
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 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 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 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

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 requirements, data from aerobic and anaerobic aquatic

metabolism studies are generally 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 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 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.
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 their 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 PCNB 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; degradates 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-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 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 associated 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, 10th 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. 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. 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/OPPTS. 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 physical-chemical property source data for PCNB

modeling.

PARAMETER VALUE

 Chemical Name pentachloronitrobenzene

 Molecular Weight 295.3

 Solubility (25 oC) 0.44 mg/L (440 ppb)

 Vapor Pressure (25 oC) 1.13 x 10-4 mmHg

 Hydrolysis Half-life (pH 5, 7, 9; 25 oC) stable (MRID’s 40865301, 40972601)

 Aqueous Photolysis Half-life (pH 7) t1/2 = 2.5 days (MRID’s 42606201, 42606202)

t1/2 = 26.8 hours (MRID 42336201)

 Soil Photolysis Half-life stable (MRID’s 41004801, 41713201)

 Aerobic Soil Metabolism Half-life t1/2 = 77, 189 days (parent only);

t1/2 = 489, 1012 days (parent plus

 PCA)1

t1/2 = 983, 1052 days (total residues)2

(MRID’s 42911902, 41384501, 41713202, 42112801)

 Anaerobic Soil Metabolism Half-life t1/2 = 9 days, <30 (DT50; parent only); 

t1/2 = 210, 410 days (parent plus

 PCA, PCP) 

t1/2 = 268, 334 days (total residues) 

(MRID’s 41203602, 42094401, 41384301, 41686001, 41713202, 42112802)

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

 Soil Partition Coefficient (Kd, mL/g) 7.3, 15.5, 19.1, 210 (MRID 41648201)

1

For the purposes of the drinking water assessment, half-lives were recalculated to account for the parent plus the degradates PCA and PCP, when

monitored and detected. 2

For the purposes of the ecological assessment, half-lives were recalculated to account for total residues, inclusive of the

parent plus the degradates PCA, PCTA, PCB, PCP, PCTASO, PCTASO2, 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 (EFED) has been requested to provide the Health

Effects Division (HED) with a drinking water assessment for Hexachlorobenzene (HCB) and

Pentachlorobenzene (PCB). A toxicological profile has 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 contaminated 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 for HCB and PCB and considered in this assessment.

SUMMARY

Hexachlorobenzene (HCB) and pentachlorobenzene (PCB) 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 (organic and inorganic) in water. It appears that
160

HCB and PCB contamination of ground water resources is relatively unlikely due to the high binding

potential of both these chlorobenzene compounds. Based 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 sediment. Higher concentrations 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 hydrocarbon 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 was 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 pentachlorobenzene 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 anticipated PCB contributions would be much less. 

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

Hexachlorobenzene (HCB).

EMISSIONS SOURCE CATEGORY1 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 ~6.35
Table 1. Summary of “Draft” Emissions Inventory Data for Pentachlorobenzene (PCB) and

Hexachlorobenzene (HCB).

EMISSIONS SOURCE CATEGORY1 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 Section 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 contaminant levels (in percent) of HCB and PCB and the

(available) product usage amounts for ten pesticides that have 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 attributed to pesticide application is not stated in Table 1;

PCB is a degradation product of the pesticide pentachloronitrobenzene (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 not complete, since product usage information was not

available for five of the pesticide. These additional 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 Usage2

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-methyl3

 --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) -- 4,000,000
Table 2. Summary of Selected Pesticides with maximum percentage of hexachlorobenzene

(HCB) and/or pentachlorobenzene (PCB) manufacturing contamination.

Active Ingredient

Maximum Contaminant (%)1 Product Usage2

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 properties 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 degradation 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 precipitation, or by dry deposition. Atmospheric transport

of HCB may be an important transport mechanism (Kelly et al., 1991). HCB concentrations in the vapor

phase represented 92 to 100 % of the total HCB concentration 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 process 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. However, 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). Photodegradation 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 (Koc 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 Koc 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 biodegradation 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 C6Cl6

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

logKoc 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-m3

/mol

1.30E-03 atm-m3

/mol

EPA, 1981

Atlas et al., 1982

Vapor Pressure@ 20 o

C 1.089E-05 mm Hg Verschueren 1983

Persistence: 

T1/2 in atmosphere 0.63 yrs (tropics/subtropics) 

1.94 yrs (temperate/boreal)

6.28 yrs (polar)

T1/2 in surface water 

(~Rate: hrs-1)

2.7 to 5.7 yrs

(2.931E-05/hr to 1.388E-05/hr)

T1/2 in ground water

 (~Rate: days-1)

5.3 to 11.4 yrs

(3.58E-04/d to 5.97E-08/d) 

T1/2 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, however, the strong adsorption can lead 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 degraded 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 bioaccumulate 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 HCB, 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 sorption 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 C6HCL5

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)

Koc 5450

3162 (Koc represents best or

average value, as appropriate,

back-calculated from log Koc). 

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, sediment, and water are reported for a considerable

time period (1971 - 1995) (USDHHS, 1996). It is my understanding from discussions here at the Agency that

pesticide manufacturers have reduced HCB and PCB contaminant 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 mean concentrations greater or equal to 0.054 ng/m3

 in

Ontario, Canada (Hoff et al. 1992). 

Sediments and Soil

HCB has been detected in soil and sediment in both agricultural areas where it was used as a

fungicide on seed grains and in urban soils near production 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 ranging 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 registered pesticide uses of

HCB rather than environmental or industrial contamination (USDHHS, 1996, after Carey et al., 1985).

Detectable levels of HCB (10 to 590 ng/g) were found in soils 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 hexachlorobenzene 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 (Oliver 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 suggested in the Toxicological Profile (USDHHS, 1996)

that there is a potential for augmenting the leaching properties of HCB and other organochlorines. The lipid

materials in bacterial cell membranes may lead to a repartitioning of hexachlorobenzene sorbed to colloids.

This could lead to a process called facilitated transport where the mobility of hydrophobic compounds such

as HCB adsorbed to soils may be enhanced by biosorption on bacteria and move to aquifers along with the

bioremedial bacterial cultures (Lindqvist and Enfield, 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 ground 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 conducted 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 would 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 their 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 fact that 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 colloidal material in the water, rather than water alone.
167

Other Monitoring Data: STORET

Monitoring data obtained from STORET are briefly discussed and presented below. STORET is

a computerized database utility maintained by the Office of Water, EPA for the STOrage and RETrieval of

chemical, physical, and biological data pertaining to the quality of waterways within and contiguous to the

United States. Geographical, political, and descriptive information 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 citizen under the Freedom of Information Act (FOIA) or

by direct access through a number of mechanisms.

The STORET data generally confirm that HCB and 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 therefore may have sorbed contaminates in the bulk water

samples. This may also explain why some of the higher 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 from 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 varies widely from one agency to the next. Therefore,

it is often recommended that prior to use of STORET 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 interprete the STORET data. The K indicates 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 interpreted exactly as reported. Other remark codes are W

which indicates that the value observed is less than the 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 concentrations 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 summarized in Appendix Table A1. The significance of these

data could not be evaluated, but are less than the value 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. Monitoring 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 wells associated with known ground water drinking water

sources. Also, due to many different analytical detection limits, no specified detection limits, or extremely

high detection limits, a detailed interpretation 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). This agrees with the high potential for binding as indicated

by the high sorption potential (high Kocs). 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 (HCB) monitoring data in water from STORET.

Method

Category

Sample Data Quality

Remark1

Number

of 

Samples

Maximum

(:g/L)

Minimum

(:g/L)

Water 

Type

397002 Total 73 0.10 0.00002 Lake

344013 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 interpreted 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

ark1

Number of

Samples

Maximum

(:g/kg)

Minimum

(:g/kg)

Water 

Type

397012 Sed dry weight bottom 131 750.00 0.001 Lake

783123 Sed wet Weight core 2 2.00 0.90 Lake

1

 Data Quality Remark: A “blank” in the remark 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 methods 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 the 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 (PCB) monitoring data in water from STORET.

Method

Category Medium

Data

Quality

Remark1

Number 

of 

Samples

Maximum

(:g/L) Minimum

(:g/L)

Water 

type

777932 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 indicates that the value should be interpreted exactly as reported. 2

 77793 - Pentachlorobenzene in whole water.

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

Method

Category 

Medium Data Quality

Remark1

Number 

of

Samples

Maximum

(:g/L)

Minimum

(:g/L)

Water 

type

391182 sediment 8 540000.0 40.00 Stream

797723 wet weight,

core

41 0.47 0.02 Stream

797904 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 indicates that the value should be interpreted 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). Concentrations 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 several 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. However, due the persistence of HCB (and PCB) in soil,

sediments, and the atmosphere, the potential for exposure from contaminated drinking water continues for

previous HCB and PCB releases in addition to continuing releases. It appears that HCB and PCB

contamination of ground-water resources is relatively unlikely 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 fewer 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 properties 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 exposure 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 quarterly samples every 3 years

Repeat Frequency If no detection 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 activated granular charcoal. The high sorption indicated by

the high Koc supports that this kind of treatment would greatly reduce HCB and PCB in water.

SELECTED REFERENCES

Carey, A.E., T.E. Dixon, H.S.C Yang. 1985. Environmental 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. Atmospheric 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. Gas- and particle-phase concentrations of alphahexachlorocyclohexane, gamma-hexachlorocyclohexane, and 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 implications for facilitated transport. Applied 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 Lakes. J. of AOAC International. 76:707-710.

Oliver, B.G. and K.D. Nicol. 1982. Chlorobenzenes 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. Concentrations 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 sorption 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 Hexachlorobenzene (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. Pesticides 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 Hexachlorobenzene (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 hexachlorobenzene accumulation in Osborne Mendel rats. J. Environ.

Pathol. Toxicol. 4:97-103.
173

Attachment. Remaining Hexachlorobenzene and pentachlorobenzene monitoring data roported in

STORET.

Table A1. Summary of remaining hexachlorobenzene (HCB) monitoring data in water from

STORET.

Method

Category

Sample Data Quality

Remark1

Number 

of

Samples

Maximum

(:g/L)

Minimum

(:g/L)

Water 

Type

390392 Water K 2 0.10 0.10 Lake

397003 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

826214 Total

Recoverable

K 1 0.02 0.02 Lake

39700 Total U 42 8.70 0.00 Ocean

344015 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 indicates that the 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. Other remark codes are W which indicates that the value observed is less than the lowest value reportable 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.

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

Remark1

Number

of

Samples

Maximum

(:g/kg;

ng/g)

Minimum

(:g/kg;

ng/g)

Water 

Type

397012 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

493433 Sieved K 34 2220.00 1.00 Lake

750424 Sed dry Weight bottom U 1 47.5 47.5 Lake

783125 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 STORET data. The K indicates that the 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 detection.

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 (PCB) monitoring data in water from STORET.

Method

Category Medium

Data

Quality

Remark1

Number 

of

Samples

Maximum

(:g/L) Minimum

(:g/L)

Water 

type

777932 “ 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. The K indicates that the 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

 77793 - Pentachlorobenzene in whole water.
175

Table A4. Summary of pentachlorobenzene (PCB) monitoring data in sediment from STORET.

Method

Category Medium Data QualityRemark1

Number

of

Samples

Maximum

(:g/kg;

ng/g)

Minimum

(:g/kg;

ng/g)

Water 

type

391182 sediment K 138 13000.0 0.00 Stream

797903 dry weight,

bottom

U 1 250.0 250.0 Stream

dry weight,

bottom

U 49 6.9 2.2 Stream

797724 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 the 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 simulations were conducted using a provisional version of PRZM

that has newer volatilization routines. This PRZM version, 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 that 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 cannot (at this time) be used to replace the values

which were determined using version 3.12 beta.

For this assessment, volatilization for PCNB was simulated without simulating temperature correction

in PRZM. Instead the Henry’s Law Constant was adjusted to reflect the mean temperature at the time of

application. This temperature was 6.2° C and is the 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 cm2

 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 diffusion 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 better estimate was made here by also considering the

molecular volume of PCNB. The specific method chosen 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 considers the properties of both. However, the air can be

considered as a single gas with defined (and constant) properties. The equation is 

where DBA is the diffusion coefficient of gas B into gas A, T is the temperature in Kelvin, Mr

 is the reduced

mass, P is the pressure, and VA and VB 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 MA and MB are the molecular masses of

gases A and B respectively. For diffusion into air,

the effective molecular mass of air (MA) is 28.97 g

mol-1 and the effective molar volume is 20.1 cm3

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 molar 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 cm2

 sec-1 or 3849 cm2

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 m3 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, )Hvap is the enthalpy

of vaporization at standard temperature and

pressure, R is the gas law constant of 8.21 x 10-5

atm m3 mol-1 K-1, T is the evaluation temperature

279.35 K (6.2° C), and T1 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 standard 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, )Hvap, to adjust the Henry’s Law constant for temperature

and it is a required input parameter even when temperature 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 Clausius-Clapeyron equation (Dickerson, 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 )Hvap is a constant. In fact, the enthalpy of vaporization is a function of temperature and is often

tabulated at two different temperatures, standard temperature 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 environment 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 Tb, the critical temperature Tc, and the critical pressure Pc.

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, )Hvap, b, according to the equation:

(5)

where R is the gas law constant, 1.9872 cal K-1 mol-1, and Kkl is an empirical correction factor that has a value

of 1.02 for Tb < 200 K, 1.04 for Tb between 200 and 300 K and 1.045 for Tb > 300. Since the boiling point

temperature for PCNB is 601.5 K (328° C), Kkl 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

Tc and Pc, these also need to be estimated.

Pc 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 Pc is:

Pc = ( . 0 34

where M is the molecular weight

and E)Pc is the sum of the critical

pressure increments as defined by

Lydersen. The calculation of E)Pc 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)Pc, 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

NO2 1 (0.42) 0.42

E)Pc 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, Tb/Tc, or 2, was estimated according to a method developed by Lydersen and described in Reid

and Sherwood, (1966) as this value appears to relatively 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 Tc is then 822 K. With values for Pc, Tc, and Tb, we can now calculate )Hvap, b using equation 3, with a

resulting value of 10640 cal mol-1.

Once we have a value for )Hvap, 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 PCNB 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

NO2 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 and 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 summarized using the Table 20 post-processor, dated April

13, 1999 which was the standard post-processor used prior 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% and 27%, respectively. The chronic values were more

greatly affected, with the 1-in-10-year 90-day mean 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%, respectively. Chronic drinking water exposures for turf

use are predicted to decrease by approximately 34%, from 65.5 ppb to 43.4 ppb. 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. One would expect full simulation of soil 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. Giddings. 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, Engineering 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, 2nd Ed. McGraw Hill Book Co., New York.``
202

Provisional PRZM9/EXAMS Modeling With Volatilization for Turf Applied Twice at 32.67 lb

ai/A/application at a 21-Day Interval

1. PRZM Files Pertaining to EEC Values 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, monthly 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 application 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 pentachloronitrobenzene to 26 week-old bobwhite quail (Colinus

virginianus) was assessed over 14 days (MRID 406180-01). The 14 day-acute oral LD50 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 observed 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 classified 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

LD50 

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 lethargy 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 birds 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 LC50 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 LC50 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 LC50 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 classified as core and are consistent with Guideline §71-2

subacute avian dietary testing requirements.
211

Table E2. Summary of subacute dietary toxicity studies with mallard ducks (Anas platyrhynchos) and

bobwhite quail (Colinus virginianus) for pentachloronitrobenzene.

Species Study

Type

% active

ingredien

t

LC50 

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 determined to be 1000 ppm based upon a reduction in

14-day survivor weight and a reduction in the percentage of 14-day hatchling survivors; the LOEC was 2,500

ppm. This avian reproduction study is scientifically sound and is consistent with Guideline §71-4 testing

requirements for an avian reproduction study using 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 effects on any reproductive parameters. The NOEC was

determined to be 5,500 ppm (the highest concentration tested) and no LOEC was determined. This study is

scientifically sound and is classified as core.

Two additional studies, bobwhite quail (MRID 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 significant 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 unusually 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 pertinent 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 LD50 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 P1 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 P2 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 thyroid 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-generation 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 LD50 >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 LD50 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 with 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

LD50

: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 LC50 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 toxicity testing with bluegill sunfish (MRID 408490-01 and 410608-

01), sublethal effects including loss of equilibrium, fish 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 concentrations ranging from 0.13 to 0.45 mg a.i./L (MRID

409927-01). Both the freshwater fish studies are consistent 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

LC50

(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 LC50 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 formulated 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 sunfish 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 guideline §71-2 testing requirements.

Table E7. Summary of freshwater fish acute toxicity in mg/L (ppm) for formulated products of

pentachloronitrobenzene.

Species % ai 96-hour

LC50 (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

core
Species % ai 96-hour

LC50 (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 stage 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 control 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 (Acc. no. 114167) was submitted using the preferred test

species Daphnia magna and is summarized in Table E10. The 48-hour LC50 was 0.77 mg/L and the NOEC

was 0.13 mg/L. All daphnids exhibited lethargy in the two highest concentrations tested. Additionally,

several daphnids were caught at the surface of test solution in the next two lower concentrations. PCNB is

categorized as highly toxic to aquatic invertebrates 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 LC50

(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-cycle 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 evaluation, this study is classified as supplemental since

the statistical analysis could not be verified. A second 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 mortality 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 aquatic 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, additional information pertaining to the

sampling methodology needs to be submitted for consideration. For study MRID 408323-02, the NOEL

(<1.2 mg a.i./l) reported is not a true NOEL but an approximation. This statement points to a whole set of

possible NOEL values where PCNB could go from being moderately toxic to being very highly toxic to the

test organism under the test conditions used. Study MRID 408829-03 determined the 96-hour LC50 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, erratic swimming behavior, lethargy, and swimming at the

surface were all observed in this test This third study is

scientifically sound and is consistent with Guideline §72-3(a) testing requirements.
219

Table E12. Summary of estuarine/marine fish acute toxicity for technical grade

pentachloronitrobenzene.

Species/Static % ai 96-hour LC50

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 toxicity of PCNB to estuarine/marine fish.

Estuarine and Marine Invertebrates, Acute

As shown in Table E13, the 96-hour mysid shrimp LC50 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 (LC50 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 requirements. For study MRID 408323-03, samples were not

filtered prior to chemical analysis, so the dissolved levels 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 data for shell thickness measurements making it impossible

to verify the statistical results. 
220

Table E13. Summary of estuarine/marine invertebrate acute toxicity for pentachloronitrobenzene.

Species % ai. 96-hour LC50

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 determine the concentration at each day after initial

application based on the concentration resulting from the initial and additional applications. The decay is

calculated from the first order rate equation:

CT = Ci

e-kT 

or in log-transformed form:

ln (CT/Ci

) = -kT

 Where:

CT = concentration at time T

Ci = concentration in parts per million (ppm) present initially (on day zero) on the surfaces.

Ci

 is calculated based on Kenaga and Fletcher by multiplying the application rate, in pounds active

ingredient per acre, by 240 for short grass, 110 for 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 studies 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/t1⁄2) 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 surface on a daily interval for one year. The maximum

concentration during the year and the average concentration 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 Fruits/pods/lg insects 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

048

1216202428323640444852

Days

Concentration (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 Fruits/pods/lg insects 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 1.35

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 0.36 0.25 0.06 9.56

Tall Grass 0.15 0.11 0.02 4.05

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 76.95 53.46 12.15

Broadleaf plants/sm insects 96.19 66.83 15.19

Fruits/pods/lg insects 14.96 10.40 2.36

Seeds (granivore) 3.31 2.36 0.47

Terresterial Application Residues

0

500

1000

1500

2000

2500

048

12

1620

2428

32

3640

4448

52

Days

Concentration (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 1350.00 830.55 Exceeded Fruits/pods/lg insects 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 2.25

Fruits/pods/lg insects 0.00 0.25

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 0.45 0.31 0.07 12.00

Tall Grass 0.21 0.14 0.03 5.50

Broadleaf plants/sm insects 0.25 0.18 0.04 6.75

Fruits/pods/lg insects 0.03 0.02 0.00 0.75

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 128.25 89.10 20.25

Fruits/pods/lg insects 14.25 9.90 2.25

Seeds (granivore) 3.15 2.25 0.45

Terresterial Application Residues

0

500

1000

1500

2000

2500

3000

048

1216

202428

323640

444852

Days

Concentration (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 450.00 276.85 Exceeded Fruits/pods/lg insects 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 0.75

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 0.16 0.11 0.03 4.25

Tall Grass 0.07 0.05 0.01 1.80

Broadleaf plants/sm insects 0.08 0.06 0.01 2.25

Fruits/pods/lg insects 0.01 0.01 0.00 0.35

Seeds (granivore) 0.00 0.00 0.00

Chronic RQ 

dose based

Chronic RQ 

dose based

Chronic RQ 

dose based

Short Grass 80.75 56.10 12.75

Tall Grass 34.20 23.76 5.40

Broadleaf plants/sm insects 42.75 29.70 6.75

Fruits/pods/lg insects 6.65 4.62 1.05

Seeds (granivore) 1.47 1.05 0.21

Terresterial Application Residues

0

100

200

300

400

500

600

700

800

900

048

1216202428323640444852

Days

Concentration (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 1862.45 1172.74

Tall Grass 853.62 537.51 # days 

Broadleaf plants/sm Insects 1047.63 659.67 Exceeded Fruits/pods/lg insects 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 1.75

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 1.75

Seeds (granivore) 2.44 1.75 0.35

Terresterial Application Residues

0

500

1000

1500

2000

048

1216202428323640444852

Days

Concentration (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 659.62 415.35

Tall Grass 279.37 175.91 # days 

Broadleaf plants/sm Insects 349.21 219.89 Exceeded Fruits/pods/lg insects 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 0.05 0.04 0.01 1.40

Broadleaf plants/sm insects 0.07 0.05 0.01 1.75

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 23.05 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

048

121620242832

3640444852

Days

Concentration (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 Fruits/pods/lg insects 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 12.16 8.45 1.92

Seeds (granivore) 2.69 1.92 0.38

Terresterial Application Residues

0

500

1000

1500

2000

2500

048

1216202428323640444852

Days

Concentration (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 725.54 469.15

Tall Grass 307.29 198.70 # days 

Broadleaf plants/sm Insects 384.11 248.37 Exceeded Fruits/pods/lg insects 59.75 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 0.05 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 25.35 5.76

Fruits/pods/lg insects 5.68 3.94 0.90

Seeds (granivore) 1.25 0.90 0.18

Terresterial Application Residues

0

100

200

300

400

500

600

700

800

048

12162024283236

40444852

Days

Concentration (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 1184.65 # days 

Broadleaf plants/sm Insects 2219.51 1453.89 Exceeded Fruits/pods/lg insects 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 0.05 9.04

Broadleaf plants/sm insects 0.42 0.29 0.07 11.10

Fruits/pods/lg insects 0.05 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 374.85 260.42 59.19

Tall Grass 171.81 119.36 27.13

Broadleaf plants/sm insects 210.85 146.49 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

048

12

16

20

24

28

32

36404448

52

Days

Concentration (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./Year 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 Fruits/pods/lg insects 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 132.76 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

048

1216202428323640444852

Days

Concentration (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 Fruits/pods/lg insects 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 2.04

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) 0.05 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 851.48 591.55 134.44

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

048

1216

2024

2832

3640444852

Days

Concentration (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 3666.65 2320.97 Exceeded Fruits/pods/lg insects 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 657.96 457.11 103.89

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

048

1216202428323640444852

Days

Concentration (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 and ecotoxicity data is called the quotient method.

For this method, risk quotients (RQs) are calculated by dividing exposure estimates by ecotoxicity values,

both acute and chronic. 

RQ = EXPOSURE/TOXICITY 

RQs are then compared to OPP's levels of concern (LOCs). These LOCs are criteria used by OPP

to indicate potential risk to nontarget organisms and the 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 risk 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. Examples of ecotoxicity values derived from the results of

short-term laboratory studies that assess acute effects are: (1) LC50 (fish and birds) (2) LD50 (birds and

mammals) (3) EC50 (aquatic plants and aquatic invertebrates) and (4) EC25 (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 risk. 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 terrestrial animals (birds and wild mammals)

Risk Presumption RQ LOC

Acute High Risk EEC1

/LC50 or LD50/ft2 or LD50/day3 0.5

Acute Restricted Use EEC/LC50 or LD50/ft2

 or LD50/day (or LD50 < 50

mg/kg)

0.2

Acute Endangered Species EEC/LC50 or LD50/ft2

 or LD50/day 0.1

Chronic Risk EEC/NOEC 1

1

 abbreviation for Estimated Environmental Concentration (ppm) on avian/mammalian food items 2

 mg/ft2 3 mg of toxicant consumed/day

 LD50 * wt. of bird LD50 * wt. of bird 
235

Table G-2. Risk presumptions for aquatic animals

Risk Presumption RQ LOC

Acute High Risk EEC1

/LC50 or EC50 0.5

Acute Restricted Use EEC/LC50 or EC50 0.1

Acute Endangered Species EEC/LC50 or EC50 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 EEC1

/EC25 1

Acute Endangered Species EEC/EC05 or NOEC 1

Aquatic Plants

Acute High Risk EEC2

/EC50 1

Acute Endangered Species EEC/EC05 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 following product application are compared to LC50 values to assess

risk. The predicted peak and mean residues of a pesticide that may be expected to 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

Residue1

EEC (ppm)

Mean1

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 associated with a lack of data on interception and

subsequent dissipation from foliar surfaces. When scientifically 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) reported by Willis and McDowell (1987).