Oryzalin_WSM_Documentation_-_Final_Report.pdf

SERA TR-056-13-03-02b

Oryzalin:

WorksheetMaker Workbook Documentation

Submitted to:

Dr. Harold Thistle USDA Forest Service

Forest Health Technology Enterprise Team 180 Canfield St.

Morgantown, WV 26505 Email: hthistle@fs.fed.us

USDA Forest Service Contract: AG-3187-C-12-0009 USDA Forest Order Number: AG-3187-D-14-0221

SERA Internal Task No. 56-13

Submitted by:

Patrick R. Durkin

Syracuse Environmental Research Associates, Inc.

8125 Solomon Seal

Manlius, New York 13104

E-Mail: SERA_INC@msn.com Home Page: www.sera-inc.com

July 30, 2015 mailto:hthistle@fs.fed.us http://www.sera-inc.com/ ii

Table of Contents

LIST OF TABLES ......................................................................................................................... iii LIST OF FIGURES ....................................................................................................................... iii REVISION NOTE ......................................................................................................................... iv ACRONYMS, ABBREVIATIONS, AND SYMBOLS ................................................................. v

1. INTRODUCTION

1.1. General Information

1.2. Chemical Specific Information

2. PROGRAM DESCRIPTION

3. HUMAN HEALTH

3.1. Hazard Identification

3.2. Exposure Assessment

3.2.1. Workers

3.2.1.1. General Exposures

3.2.1.2. Accidental Exposures

3.2.2. General Public

3.2.1.1. Surface Water

3.2.2.2. Vegetation

3.2.2.3. Bioconcentration

3.2.2.4. Dermal Exposure

3.3. Dose-Response Assessment

3.3.1. Acute Toxicity

3.3.2. Chronic Toxicity

3.3.3. Carcinogenicity

3.4. Risk Characterization

3.4.1. Workers

3.4.2. General Public

4. ECOLOGICAL EFFECTS

4.1. Hazard Identification

4.2. Exposure Assessment

4.2.1. Bioconcentration

4.2.2. Offsite Contamination of Soil

4.2.3. Surface Water

4.3. Dose-Response Assessment

4.3.1. Terrestrial Organisms

4.3.1.1. Mammals

4.3.1.2. Birds

4.3.1.2.1 Acute Toxicity

4.3.1.2.2 Chronic Toxicity

iii

4.3.1.3. Amphibians, Terrestrial-Phase

4.3.1.4. Honey Bee

4.3.1.5. Terrestrial Plants

4.3.2. Aquatic Organisms

4.3.2.1 Fish

4.3.2.1.1. Peak Exposures

4.3.2.1.2. Longer-term Exposures

4.3.2.2 Amphibians (Aquatic-phase)

4.3.2.3. Aquatic Invertebrates

4.3.2.3.1. Peak Exposures

4.3.2.3.2. Longer-term Exposures

4.3.2.4. Aquatic Plants

4.3.2.4.1. Algae

4.3.2.4.2. Aquatic Macrophytes

4.4. Risk Characterization

5. REFERENCES

5.1. Chemical Specific References

5.2. Standard Reference

LIST OF TABLES

Table 1: Chemical and Physical Properties Table 2: Inputs and Outputs for FIRST Simulations Table 3: Summary of toxicity values used in human health risk assessment Table 4: Summary of toxicity values used in ERA

LIST OF FIGURES

Figure 1: Current Uses of Oryzalin in the U.S iv

REVISION NOTE

This report is a modification to SERA TR-056-13-03-01a, Oryzalin:

WorksheetMaker Workbook Documentation, dated January 6, 2015. Changes to this workbook are based on the following comments from the Forest Service:

Notes from John Justin and Shawna Bautista in an EXCEL workbook (Mancozeb SAMPLE Workbook-SB-JJ.xlsm) via an email from Shawna Bautista dated 6/2/2015.

Comments from John Justin in a Microsoft Word file (Query Template for WSM Input Effort.docx) via an email from Shawna Bautista dated 12/30/2014.

The most recent set of comments (i.e., the EXCEL workbook from 6/2/2015) is given precedence when the feedback is inconsistent.

v

ACRONYMS, ABBREVIATIONS, AND SYMBOLS

AEL adverse-effect level a.e. acid equivalent a.i. active ingredient a.k.a. also known as a.s. active substance AOEL acceptable occupational exposure limit APHIS Animal and Plant Health Inspection Service ATSDR Agency for Toxic Substances and Disease Registry ASAE American Society of Agricultural Engineers BCF bioconcentration factor bw body weight calc calculated value CBI confidential business information CI confidence interval cm centimeter CNS central nervous system COC crop oil concentrates DAA days after application DAT days after treatment DER data evaluation record d.f. degrees of freedom EC emulsifiable concentrate ECx concentration causing X% inhibition of a process EC25 concentration causing 25% inhibition of a process EC50 concentration causing 50% inhibition of a process ECOTOX ECOTOXicology (database used by U.S. EPA/OPP) EEC expected environmental concentration EFED Environmental Fate and Effects Division (U.S. EPA/OPP) ERA ecological risk assessment ExToxNet Extension Toxicology Network F female FH Forest Health FIFRA Federal Insecticide, Fungicide and Rodenticide Act FQPA Food Quality Protection Act g gram GLP Good Laboratory Practices ha hectare HED Health Effects Division (U.S. EPA/OPP) HHRA human health risk assessment HIARC Hazard Identification and Assessment Review Committee (part of U.S. EPA/OPP/HED) HQ hazard quotient HRAC Herbicide Resistance Action Committee IARC International Agency for Research on Cancer IRED Interim Reregistration Eligibility Decision IRIS Integrated Risk Information System vi ka absorption coefficient ke elimination coefficient kg kilogram Ko/c organic carbon partition coefficient Ko/w octanol-water partition coefficient Kp skin permeability coefficient L liter lb pound LC50 lethal concentration, 50% kill LD50 lethal dose, 50% kill LOAEL lowest-observed-adverse-effect level LOC level of concern LR50 50% lethal response [EFSA/European term] m meter M male mg milligram mg/kg/day milligrams of agent per kilogram of body weight per day mL milliliter mM millimole mPa millipascal, (0.001 Pa) MITC methyl isothiocyanate MOS margin of safety MRID Master Record Identification Number MSDS material safety data sheet MSO methylated seed oil MW molecular weight NOAEL no-observed-adverse-effect level NOEC no-observed-effect concentration NOEL no-observed-effect level NOS not otherwise specified N.R. not reported OPP Office of Pesticide Programs ppm parts per million RED re-registration eligibility decision RfD reference dose SERA Syracuse Environmental Research Associates T.G.I.A. Technical grade active ingredient UF uncertainty factor U.S. United States USDA U.S. Department of Agriculture U.S. EPA U.S. Environmental Protection Agency USGS U.S. Geological Survey WHO World Health Organization

1. INTRODUCTION 1

1.1. General Information 2

This document supports the development of a WorksheetMaker EXCEL workbook for the 3 subject pesticides. As detailed in SERA (2011a), WorksheetMaker is a utility that automates the 4 generation of EXCEL workbooks that accompany Forest Service risk assessments, and these 5 EXCEL workbooks are typically generated in the development of Forest Service risk 6 assessments (SERA 2014). 7 The development of full Forest Service risk assessments, however, is resource intensive. For 9 some pesticides that are used in only relatively small amounts and/or only in few locations, the 10 development of full Forest Service risk assessments is not feasible. Nonetheless, the Forest 11 Service may be required to develop risk analyses supported by WorksheetMaker EXCEL 12 workbooks. To meet this need, an MS Word utility was developed to facilitate the addition of 13 pesticides and pesticide formulations into the Microsoft Access database used by 14 WorksheetMaker (SERA 2011b). With this addition, WorksheetMaker can be used to generate 15 EXCEL workbooks typical of those that accompany Forest Service risk assessments. 16 The current document is designed to serve as documentation for the application of this general 18 method for the pesticide discussed in Section 1.2. The major difference between this approach to 19 using WorksheetMaker and the typical use of WorksheetMaker in the development of Forest 20 Service risk assessments involves the level of documentation and the sources used in developing 21 the documentation. While standard Forest Service risk assessments involve a relatively detailed 22 review and evaluation of the open literature and publically available documents from the U.S. 23 EPA, as discussed further in Section 1.2, the current assessment relies primarily on secondary 24 sources with minimal independent evaluation of the data. 25

1.2. Chemical Specific Information 26

The current document concerns oryzalin. The initial information on oryzalin was identified at 27 the U.S. EPA’s Pesticide Chemical Search website (http://iaspub.epa.gov/apex/pesticides/f?p= 28 CHEMICALSEARCH:1:11098277289067::NO:1::) using the search term “oryzalin”. Other information 29 was identified through custom searches of EPA and a NMFS (National Marine Fisheries Service) 30 web site for the recent biological opinion involving oryzalin (NMFS 2012). 31 Oryzalin is a dinitroanaline preemergence herbicide. U.S. EPA’s Pesticide Chemical Search 33 website lists 4 E-Dockets on oryzalin and 59 cleared science reviews. TOXLINE 34 (http://toxnet.nlm.nih.gov) contains 527 open literature citations using synonyms and 279 35 citations not using synonyms. The distinction between using and not using synonyms is 36 important in that using synonyms may lead to irrelevant citations (most often due to formulation 37 names), and not using synonyms may result in missing some relevant citations. Overall, the 38 literature on oryzalin may be viewed as modest. 39 Information relating to the human health effects of oryzalin is taken primarily from the Report of 41 the Food Quality Protection Act (FQPA) Tolerance Reassessment Progress and Risk 42 Management Decision (TRED) for Oryzalin (U.S. EPA/OPP 2004) supplemented by information 43 from the RED on oryzalin (U.S. EPA/OPP 1994a). Information on ecological effects and the 44 environmental fate of oryzalin is taken primarily from the EPA’s assessment of the potential 45 http://iaspub.epa.gov/apex/pesticides/f?p=%20CHEMICALSEARCH:1:11098277289067::NO:1 http://iaspub.epa.gov/apex/pesticides/f?p=%20CHEMICALSEARCH:1:11098277289067::NO:1 http://toxnet.nlm.nih.gov/ effects of oryzalin on the California tiger salamander, an endangered species (U.S. 1 EPA/OPP/EFED 2010). Ecological effects data are also covered in the National Marine 2 Fisheries Service biological opinion on oryzalin (NMFS 2012). The NMFS (2012) analysis 3 covers pendimethalin and trifluralin as well as Oryzalin; thus, the document is somewhat 4 unwieldy—i.e., about 30 megabytes with over 1000 pages. Consequently, NMFS (2012) was 5 consulted but not reviewed in detail during the preparation of the current assessment on oryzalin. 6 Additional information about oryzalin is taken from Tomlin (2004), ChemIDplus (2014) and EPI 7 Suite (2011). 8 This document is accompanied by two MS Word files: Oryzalin WMS Formulation 10 Inputs.docx and Oryzalin WSM Chemical Inputs.docx. These files can be used 11 with the MS Word utility, SERA (2011b), to add oryzalin to the database used by 12 WorksheetMaker. This document is also accompanied by a WorksheetMaker EXCEL 13 workbook, Oryzalin SAMPLE Workbook.xlsm. Forest Service personnel may modify 14 this workbook for program specific activities. 15

2. PROGRAM DESCRIPTION 17

Oryzalin is an herbicide registered in the United States since 1974. Oryzalin was developed in 18 the late 1960s and was first marketed in Bulgaria in 1973 by Eli Lilly (now Dow AgroSciences). 19 Oryzalin is used for preemergence control of both grasses and broadleaved weeds on a variety of 20 crops, including cotton, fruit trees, nut trees, vines, ornamentals, soya beans, berries, rice, 21 amenity turf and non-crop areas (Tomlin 2004). The U.S. EPA registration review program 22 operates on a 15-year cycle. Oryzalin was reregistered in 1994 (U.S. EPA/OPP 1994a) and is 23 currently under registration review, which is scheduled to be completed in 2016 (U.S. EPA/OPP 24 2011). 25 Table 1 summarizes the chemical and physical properties as well as environmental fate 27 characteristics of oryzalin. Oryzalin is only moderately persistent, and photodegradation (in both 28 soil and water) appears to be the major breakdown mechanism (U.S. EPA/OPP/EFED 2010, p. 29 16). At least 12 metabolites of oryzalin have been identified (e.g., U.S. EPA/OPP/EFED 2010, 30 Table 2). A characteristic of all identified metabolites is that the benzenesulfonamide ring 31 remains intact. No metabolites of concern are designated in EOA risk assessments (i.e., U.S. 33 EPA/OPP 1994a, 2004; U.S. EPA/OPP/EFED 2010), and the TRED for oryzalin specifically 34 notes: Oryzalin does not appear to produce a toxic metabolite produced by other substances 35 (U.S. EPA/OPP 2004, p. 4). Consequently, the EPA has not addressed cumulative risks from 36 oryzalin with other substances having the same mode of action. 37 As of 2011 (the most recent year for which data are available), the USGS estimates an upper end 39 annual use of oryzalin in the United States of about 900,000 pounds 40 (http://water.usgs.gov/nawqa/pnsp/usage/maps/show_map.php?year=2011&map=ORYZALIN&41 hilo=L&disp=Oryzalin). As illustrated in Figure 1, oryzalin is currently used primarily on 42 orchards and grapes. 43 http://water.usgs.gov/nawqa/pnsp/usage/maps/show_map.php?year=2011&map=ORYZALIN&hilo=L&disp=Oryzalin

Based on the most recent EPA risk assessment (i.e., U.S. EPA/OPP/EFED 2010, Table 2.3), the 2 maximum single application rate for oryzalin is 6 lbs a.i./acre with a maximum cumulative 3 annual application rate of 15 lbs a.i./acre. The PAN Pesticides Database currently lists 67 active 4 formulations of oryzalin in the United States (Kegley et al. 2014). 5 While the current document is intended to be useful in any small scale application of oryzalin, it 7 is focused on the use of oryzalin at the JH Stone Nursery in the Rogue River-Siskiyou National 8 Forest. Based on information from this nursery, the Forest Service will use Surflan AS (40.4% 9 oryzalin) (Justin 2014). According to the most recent label (May 18, 2014) at the EPA label site 10 (http://iaspub.epa.gov/apex/pesticides/f?p=PPLS:8:8209936233516 ::NO::P8_PUID:2909), 11 Surflan AS Specialty Herbicide (EPA Registration Number 70506-44) contains oryzalin as the 12 sole active ingredient at a concentration of 4 lbs a.i./gallon. The maximum single application 13 rate is 2 lbs a.i./acre. Up to 2 applications per year are permitted with a minimum application 14 interval of 3 months. As with other formulations of oryzalin, Surflan AS is labelled for the 15 control of both grasses and broadleaf weeds. This formulation is labeled for both backpack 16 (directed foliar) and ground broadcast application. 17 At the JH Stone Nursery, oryzalin will be used at an application rate of 2 lbs a.i./acre and an 19 application volume of 30 gallons/acre. Two applications will be made with a 3-month 20 application interval as a broadcast spray through tractor mounted spray booms. Workers will 21 apply oryzalin by ground broadcast through tractor mounted spray booms, and treatment will be 22 made at a rate of 5 acres/hr for 4 hours. Thus, 20 acres will be treated for a total use of 40 lbs per 23 application with 80 pounds being used at the nursery per year. 24 Based on other information from the Forest Service (the illustration in JH Stone Nursery 26 Information-v3 Shawna Aug 21.docx), the JH Stone nursery is about 220 acres in 27 size. Taking 20 acres as the treated area, a proportion of about 0.091 [20 acres ÷ 220 acres ≈ 28 0.090909…] of the nursery area will be treated. As discussed further in Section 3.2.2.1, this 29 proportion is used to modify the water contamination rates. 30 http://iaspub.epa.gov/apex/pesticides/f?p=PPLS:8:8209936233516%20::NO::P8_PUID:2909

3. HUMAN HEALTH 1

3.1. Hazard Identification 2

While full Forest Service risk assessments provide a detailed discussion of the available toxicity 3 data on the pesticide under consideration, this approach is not taken in the current document, in 4 the interest of economy. The toxicology of oryzalin is discussed in detail in the Reregistration 5 Eligibility Decision (RED) document on oryzalin (U.S. EPA/OPP 1994a) as well as the 6 Tolerance Reassessment Progress and Risk Management Decision (TRED) for oryzalin (U.S. 7

EPA/OPP 2004). 8

As noted in Section 2, the EPA does not specifically address cumulative effects for oryzalin. 10 The rationale for this approach is given below. 11

Unlike other pesticides for which EPA has considered cumulative risk based 13 on a common mechanism of toxicity, EPA has not made a common mechanism 14 of toxicity finding for oryzalin. The Agency has found no information 15 indicating oryzalin shares a common mechanism of toxicity with other 16 substances. Oryzalin does not appear to produce a toxic metabolite produced 17 by other substances. Therefore, for the purposes of the risk assessments, EPA 18 has not assumed that oryzalin has a common mechanism of toxicity with other 19 substances. 20

U.S. EPA/OPP (2004, p. 3) 21 While the toxicity of oryzalin is relatively well characterized in plants (Section 4.1), a specific 23 mechanism of action in humans and other mammals is not identified in EPA risk assessments. 24 Overall, oryzalin does not appear to be highly toxic to mammals on an acute basis. Oryzalin is 25 classified as Category IV (least toxic category) in terms of acute oral toxicity and Category III in 26 terms of acute dermal and inhalation toxicity as well as eye irritation. Oryzalin is also classified 27 as non-sensitizing (U.S. EPA/OPP 1994a). 28 In terms of chronic effects, the most sensitive endpoint for toxicity appears to be the thyroid. As 30 discussed further in Section 3.3, thyroid lesions along with decreased body weight gain and 31 changes in hematology parameters are the basis of the chronic RfD (U.S. EPA/OPP 2004a). In 32 addition to systemic toxicity, chronic exposures to oryzalin may cause cancer based on an 33 increase in thyroid follicular cell tumors. Specifically, oryzalin is classified as “likely to be 34 carcinogenic to humans” (U.S. EPA/OPP 2004, p. 15). Because of the toxicity and 35 carcinogenicity of oryzalin to the thyroid, the EPA may require … additional screening and/or 36 testing to better characterize effects related to endocrine disruption when the Agency’s 37 Endocrine Disrupter Screening and Testing Advisory Committee develops appropriate screening 38 and/or testing protocols (U.S. EPA/OPP 2004, p. 4). The most recent EPA assessment relating 39 to the registration review of oryzalin notes a concern for endocrine disruption but does not 40 indicate if additional testing has been done on oryzalin (U.S. EPA/OPP 2011, p. 6). Endocrine 41 disruption is also a concern in the ecological risk assessment; however, the most recent EPA 42 ecological risk assessment on oryzalin does not discuss endocrine disruption (U.S. 43

EPA/OPP/EFED 2010). 44

3.2. Exposure Assessment 1

3.2.1. Workers 2

3.2.1.1. General Exposures 3

As discussed in SERA (2014b), Forest Service risk assessments use a standard set of worker 4 exposure rates (Table 14 in SERA 2014b). The current document is concerned with ground 5 broadcast applications. As detailed in Table 14 of SERA (2014b), the occupational exposure rate 6 for ground broadcast applications is 0.0001 (0.000002 to 0.005) mg/kg bw per lb a.i. handled 7 based on the central estimate of exposure and 95% prediction intervals. 8 U.S. EPA/OPP (1994a) estimates exposure to ground broadcast workers as 0.01 mg/kg bw/day 10 (U.S. EPA/OPP 1994a, Table 4, p. 19) based on the treatment of 80 acres/day (U.S. EPA/OPP 11 1994a, Table 4, p. 18) at an application rate of 6 lbs a.i./acre (U.S. EPA/OPP 1994a, Table 2, p. 12 17). This estimate corresponds to a worker exposure rate of 0.000021 mg/kg bw/day per lb a.i. 13 handled [0.01 mg/kg bw ÷ (6 lb a.i./acre x 80 acres)]. 14 The central estimate of the worker exposure rates from SERA (2014b) is about a factor of 5 16 higher than the corresponding rates from U.S. EPA/OPP (1994a) [0.0001 ÷ 0.00021 = 4.8]. As 17 discussed in SERA (2014b), worker exposure rates are highly variable, and difference of a factor 18 of 5 is large but not unusually so given the variability in worker exposure rates. 19 As detailed in SERA (2014b, Section 4.2 and Table 14), worker exposure rates for directed 21 ground applications should be adjusted for dermal exposure rates of the chemical of concern, 22 relative to the reference chemical on which occupational exposure rates are based. This is not 23 the case for broadcast ground applications, for which the adjustment of dermal absorption is 24 optional. As specified in SERA (2014b, Table 14), there is only one reference chemical for 25 ground broadcast applications—i.e., 2,4-D with a first-order dermal absorption rate of 26

0.00066 hour-1. As detailed in the following section, the estimated first-order dermal absorption 27 rate for oryzalin is 0.0026 hour-1, which is a factor of about 4 higher than the corresponding rate 28 for 2,4-D [0.0026 hour-1 ÷ 0.00066 hour-1 ≈ 3.9393…]. Thus, adjusting the occupational 29 exposure rate upward by a factor of 4 would lead to an occupational exposure rate higher than 30 that from EPA by a factor of about [4.8 x 3.94 ≈ 18.912]. This difference from EPA is not 31 justified by the available data, and the option to adjust the occupational exposure rate for 32 oryzalin is not exercised in the current analysis. 33

3.2.1.2. Accidental Exposures 34

In addition to general exposures, four standard accidental exposure scenarios for workers 35 discussed in SERA (2014a, Section 3.2.2.2) are also considered in the current assessment and 36 detailed in Worksheets C02a,b and C03a,b. 37 Worksheets C03a,b involve accidental spills under the assumption of first-order dermal 39 absorption. Based on a dermal absorption study in Rhesus monkeys, U.S. EPA/OPP (2004, p. 40

20) uses a dermal absorption factor of 2.3%. This factor is used for exposures over the course of 41 a work day (8 hours) and corresponds to an estimated first-order dermal absorption rate of about 42

0.0029 hour-1 [ka = -ln(1-0.023)÷8 hours ≈ 0.00291 hour-1]. 43

In the absence of experimental data, Forest Service risk assessments use an algorithm based on 1 the molecular weight and octanol water partition coefficient (Kow) to approximate a first-order 2 dermal absorption rate coefficient (see Eq. 23, Section 3.1.3.2.2 in SERA 2014a). As detailed in 3 Worksheet B03b of the WorksheetMaker workbook that accompanies this report, the estimated 4 first-order dermal absorption rate coefficient for oryzalin based on this algorithm is 0.0026 5 (0.0011 to 0.0062) hour-1 based on a molecular weight of 346.35 and Kow of 5370 (Table 1 6 values from U.S. EPA/OPP 1994a for molecular weight and EPA/OPP/EFED 2010 for Kow). 7 The central estimate of the ka (0.0026 hour-1) is from the SERA (2014a) algorithm is virtually 8 identical to the estimate of 0.0029 hour-1 from U.S. EPA/OPP (2004). Given the concordance of 9 the two estimates, the current assessment uses the ka values of 0.0026 (0.0011 to 0.0062) hour-1 10 from the SERA (2014a) algorithm to more explicitly account for the uncertainty of the estimate. 11 Worksheets C02a,b involve contaminated gloves under the assumption of zero-order dermal 13 absorption. These scenarios require an estimate of the skin permeability coefficient (kp in units 14 of cm/hr). No experimental measurements of kp were identified in the literature reviewed for this 15 report (Section 1.2). Consequently, the kp is estimated using an algorithm developed by the U.S. 16 EPA’s Office of Research and Development as discussed in SERA (2014a, 3.1.3.2.1). The 17 application of this algorithm to oryzalin is detailed in Worksheet B03a of the WorksheetMaker 18 workbook that accompanies this document. The values in Worksheets C02a,b are rounded to 19

0.0060 (0.0034 to 0.011) cm/hr and are used in all exposure scenarios based on zero-order 20 dermal absorption. 21

3.2.2. General Public 22

As detailed in SERA (2014a, Section 3.2.3), Forest Service risk assessments provide a standard 23 set of exposure scenarios for members of the general public. These exposure scenarios are 24 applicable to standard forestry applications of pesticides and are included in the 25 WorksheetMaker workbook that accompanies this document. 26

3.2.1.1. Surface Water 27

While most of the exposure scenarios given in the WorksheetMaker workbook are standard for 28 Forest Service risk assessments, one notable exception is the surface water modelling. Full 29 Forest Service risk assessments typically estimate concentrations of a pesticide in surface water 30 using GLEAMS-Driver (SERA 2014a, Section 3.2.3.4.3). In the interest of economy, the current 31 analysis uses FIRST (FQPA Index Reservoir Screening Tool). FIRST is a Tier 1 model 32 developed by the U.S. EPA to estimate pesticide concentrations in surface water. Details of the 33 FIRST model are available at http://www.epa.gov/oppefed1/models/water/first_description.htm. 34 The input parameters and the estimated surface water concentrations of oryzalin are summarized 36 in Table 2. The model runs involved two applications of 1 lb a.i./acre with an application 37 interval of 60 days. This is the number of applications and the application interval that is 38 proposed for the JH Stone Nursery. Note that the upper bound of the Koc is used to estimate the 39 lower bound peak concentrations and the lower bound of the Koc is used to estimate the upper 40 bound of peak concentrations. For the upper bound estimates of concentrations in surface water, 41 the opposite approach is taken—i.e., lower bound of the Koc is used to estimate the upper bound 42 of peak concentrations and the upper bound of the Koc is used to estimate peak longer-term 43 concentrations. This approach is taken because low values for Koc (less soil binding) will lead to 44 higher peak concentrations which in turn lead to lower longer-term concentrations. 45 http://www.epa.gov/oppefed1/models/water/first_description.htm

One very important input parameter for FIRST is the proportion of the watershed that is treated. 2 As indicated in Table 2, the FIRST modeling was conducted using a proportion of 1.0—i.e., the 3 entire watershed is treated. As discussed in Section 2, the proportion of the JH Stone Nursery 4 that will be treated is about 0.091. This factor is used in Table 2 to adjust the estimated water 5 contamination rates. These adjusted water contamination rates are entered into Worksheet 6 B04Rt as water contamination rates—i.e., mg/L per lb a.i./acre applied. 7

3.2.2.2. Vegetation 8

As detailed in SERA (2014a, Section 3.2.3.7), several scenarios involving the consumption of 9 contaminated vegetation are included in workbooks produced by WorksheetMaker for pesticides 10 applied to foliage. The major input parameters are application rate, number of applications, and 11 application interval. As with surface water concentrations, the residues in vegetation are entered 12 into WorksheetMaker as normalized rates in units of mg/kg vegetation per pound a.i. applied per 13 acre. 14 For longer-term exposures, half-lives on vegetation are important parameters. Little information 16 is available on vegetation half-lives of oryzalin. Knisel and Davis (2000) recommend a foliar 17 half-life of 5 days, and U.S. EPA/OPP/EFED (2010, p. 70) uses a default half-life of 35 days 18 adapted from Willis and McDowell (1987). Willis and McDowell (1987) do not list a foliar half-19 life for oryzalin. Based on these data, the lower and upper bounds of the foliar half-life for 20 oryzalin are taken as 5 to 35 day. The central estimate of 13 days is used based on the geometric 21 mean of the lower and upper bounds. 22

3.2.2.3. Bioconcentration 23

As discussed in SERA (2014a, Section 3.2.3.5), scenarios involving the consumption of 24 contaminated fish are included in most WorksheetMaker workbooks. The major chemical 25 specific inputs are the concentrations in surface water (discussed in Section 3.2.1.1 of this 26 document) and the bioconcentration factor (BCF). For exposure scenarios involving humans, the 27 BCF is based on the edible portion (muscle) in fish. For the ecological risk assessment, the BCF 28 is based on whole fish. When adequate data are available, separate BCF values may be given for 29 acute exposures and longer-term exposures. 30 Very little information on the bioconcentration of oryzalin is included in the documents 32 consulted (Section 1.2). U.S. EPA/OPP (1994a, p. 29, MRID 40787501; U.S. EPA/OPP/EFED 33 2010) cite bioconcentration factors of about 32 in the edible portion of fish and 66 in whole fish. 34 These values are used for both acute a longer-term exposure assessments involving the 35 consumption of contaminated fish. 36

3.2.2.4. Dermal Exposure 37

As in the accidental exposure assessments for workers (Section 3.2.1.2 of the current document), 38 dermal exposure scenarios involving both first-order and zero-order absorption are used in 39 scenarios for members of the general public. Details of these exposure scenarios are given in 40 SERA (2014a, Sections 3.2.3.3 and 3.2.3.6). The dermal absorption values used in these 41 scenarios are identical to those used for workers (Section 3.2.1.2). 42

3.3. Dose-Response Assessment 1

The dose-response assessments for oryzalin are summarized in Table 3. All of the toxicity 2 values are taken from EPA’s tolerance reassessment for oryzalin (U.S. EPA/OPP 2004) with 3 supplemental information taken from the Reregistration Eligibility Decision (RED) for oryzalin 4 (U.S. EPA/OPP 1994a). 5

3.3.1. Acute Toxicity 6

The acute RfD for oryzalin is 0.25 mg/kg bw/day (U.S. EPA/OPP 2004, p. 14). This acute RfD 7 uses an uncertainty factor of 100 and is based on a developmental study in rabbits in which the 8 NOAEL is 25 mg/kg bw/day and the LOAEL is 55 mg/kg bw/day based on fetal toxicity—i.e., 9 decreases in the number of live fetuses, increased resorptions, and increased post-implantation 10 losses. U.S. EPA/OPP (2004) does not specify the study on which the acute RfD is based. The 11 information in U.S. EPA/OPP (1994a) clearly indicates that the RfD is based on MRID 12 00026785. U.S. EPA/OPP (2004) applies this study only to women of childbearing age. 13 Following the standard practice in Forest Service risk assessments, this acute RfD is applied to 14 the general population. 15

3.3.2. Chronic Toxicity 16

The chronic RfD for oryzalin is 0.14 mg/kg bw/day (U.S. EPA/OPP 2004, p. 15). The chronic 17 RfD also uses an uncertainty factor of 100 and is based on a chronic study in rats with a NOAEL 18 of 14 mg/kg bw/day and a LOAEL of 43 mg/kg bw/day based on histopathological changes in 19 thyroid tissue. U.S. EPA/OPP (2004) does not specify the study on which the chronic RfD is 20 based. The information in U.S. EPA/OPP (1994a) suggests that the chronic RfD is based on 21 MRIDs 00070569, 00026779, 00044332. Complex studies such as chronic studies in mammals 22 are often associated with multiple MRID submissions. U.S. EPA/OPP (1994a) gives a slightly 23 lower chronic RfD of 0.12 mg/kg bw/day. This minor inconsistency is not unusual and probably 24 reflects either a subgroup in the study (e.g., males or females) or a recalculation of body weight 25 and food consumption data. 26 The U.S. EPA/OPP sometimes derives a separate toxicity value for workers. This is not the case 28 for oryzalin. 29

3.3.3. Carcinogenicity 30

U.S. EPA/OPP (2004) classifies oryzalin as “likely to be carcinogenic to humans” and sets a 31 level of concern for carcinogenicity of 1 in 1-million (U.S. EPA/OPP 2004, p. 15) with a cancer 32 potency factor of 0.0078 (mg/kg bw/day)-1 based on thyroid tumors. Potency factors are not 33 used directly in WorksheetMaker. Instead, the values for carcinogenicity are based on a dose 34 associated with a risk of 1-in-1 million. Risk is simply the product of potency and dose [Risk = 35 Potency x Dose]. By rearrangement, the dose associated with a risk of 1-in-1 million (0.000001) 36 is calculated as 0.000001 divided by the potency. Thus, the dose associated with a risk of 1-in-1 37 million is 0.00013 mg/kg bw/day mg/kg bw/day [0.000001 ÷ 0.0078 (mg/kg bw/day)-1 ≈ 38

0.0001282 mg/kg bw/day]. 39 U.S. EPA/OPP (1994a) gives a much higher cancer potency factor of 0.13 (mg/kg bw/day)-1 41 based on mammary gland tumors in both sexes and fibroadenomas in female rats. U.S. 42 EPA/OPP (2004) does not discuss this higher potency factor or the reasons for using a lower 43 potency factor based on thyroid tumors. A cursory review of cleared science reviews from EPA 44 suggests that this decision is based on an EPA reassessment of the carcinogenicity data on 1 oryzalin (U.S. EPA/OPP/HED 2003). While this reassessment was not reviewed in detail as part 2 of the current effort, it is clear that EPA recommends the use of thyroid rather than mammary 3 gland tumors for the assessment of cancer potency. 4

The Committee recommended that a linear low-dose extrapolation approach for 6 the quantification of human cancer risk be applied to the experimental animal 7 tumor data and that quantifications of risk be estimated for thyroid follicular cell 8 tumors which were seen in both sexes in rats. 9

U.S. EPA/OPP/HED (2003, p. 36). 10 For the current analysis, the cancer potency factor of 0.0078 (mg/kg bw/day)-1 based on thyroid 12 tumors is used. Note that this potency factor is associated with lifetime risk. As detailed above, 13 the dose associated with a lifetime risk of 1-in-1 million is 0.00013 mg/kg bw/day mg/kg 14 bw/day. 15 For the analysis relating to the JH Stone Nursery, lifetime exposures are not anticipated. For 17 less-than-lifetime exposures, the U.S. EPA recommends estimating a dose based on an 18 equivalent lifetime exposure: 19

Unless there is evidence to the contrary in a particular case, the cumulative dose 21 received over a lifetime, expressed as average daily exposure prorated over a 22 lifetime, is recommended as an appropriate measure of exposure to a carcinogen. 23 That is, the assumption is made that a high dose of a carcinogen received over a 24 short period of time is equivalent to a corresponding low dose spread over a 25 lifetime. 26

U.S. EPA/RAF (2005, p. 3-26). 27 The above approach is essentially identical to the application of Haber’s Law as discussed in 29 SERA (2014a, p. 145). 30 Taking 70 years as a standard value for a human lifetime, the number of days of exposure for a 32 lifetime dose would be 25,000 day [70 years x 365.25 day = 25,567.5 days]. Thus, a lifetime 33 dose of 0.00013 mg/kg bw/day would be equivalent to a single dose of about 3.32 mg/kg bw 34 [0.00013 mg/kg bw/day x 25,000 days = 3.323775 mg/kg bw]. This dose may be viewed as the 35 dose associated with a 1-day exposure resulting in a lifetime risk of 1-in-1 million. This dose is 36 used in the workbook that accompanies the current risk assessment to estimate HQs for cancer 37 that would be associated with an exposure for a single day. This risk is incremental. For 38 example, an exposure for 10 days would be associated with a risk of 1-in-100,000. 39

3.4. Risk Characterization 41

3.4.1. Workers 42

As summarized in Worksheet E02, the HQs for workers associated with general exposures in the 43 broadcast ground application of oryzalin are 0.03 (0.0006-1.4). Based on the central estimate of 44 exposure (i.e., the most likely exposure), the HQ is below the level of concern by a factor of 45 about 33 [1÷0.03 = 33.333…]. The upper bound of 1.4 modestly exceeds the level of concern. 1 As discussed in SERA (2014b), the upper bound is based on a prediction interval, which is more 2 conservative than a confidence interval. It seems reasonable to assert that concerns for the upper 3 bound HQ could be adequately addressed by ensuring proper handling and proper use of PPE. 4 As summarized in Worksheet E05, the HQs for workers based on carcinogenicity are 0.001 6 (0.00002 to 0.06). As discussed in Section 3.3.3, these HQs are associated with a single day’s 7 exposure. Thus, based on the central estimate of the HQ, a worker would need to apply oryzalin 8 for 1000 days [1 ÷ 0.001 day-1] to reach a cancer risk of 1-in-1-million. Based on the upper 9 bound of 0.06, however, only about 17 days would be required to reach this risk [1 ÷ 0.06 day-1 ≈ 10 16.666…]. Based on the information from the JH Stone Nursery, however, workers would apply 11 oryzalin for only a single full day—i.e., 2 days at 4 hours/day. Thus, a single worker would need 12 to apply oryzalin at this nursery for a period of about 17 years to exceed a cancer risk of 1-in-1 13 million. 14 As discussed in Section 3.2.1.1, the U.S. EPA/OPP (1994a) estimates an exposure of 0.01 mg/kg 16 bw/day for workers applying oryzalin by ground broadcast application. Based on the cancer 17 potency factor of 0.13 (mg/kg bw/day)-1, the risk [Dose x Potency] to workers would be about 18 [0.13 (mg/kg bw/day)-1 x 0.01 mg/kg bw/day = 0.0013 or about 1 in 769]. The highest worker 19 risk given in U.S. EPA/OPP (1994a, p. viii) is 2.6x10-4. It seems possible that the EPA made 20 adjustments for less-than-lifetime exposures in U.S. EPA/OPP (1994a), similar to those detailed 21 in Section 3.3.3 of the current report. 22

3.4.2. General Public 23

As summarized in Worksheet E04, accidental exposure scenarios lead to HQs that exceed the 24 level of concern based on an accidental spill. The highest HQs are associated with the 25 consumption of contaminated fish by subsistence populations—i.e., HQs of 4 (0.9-9). In the 26 event of an accidental spill, aggressive measures would be justified to limit exposures to the 27 general public. For non-accidental exposures, the only HQs of concern (HQ>1) are those 28 associated with the consumption of contaminated vegetation. The upper bound HQs for the 29 consumption of contaminated vegetation are 13 for acute exposures and 11 for longer-term 30 exposures. Concerns for these HQs can be mitigated by ensuring that members of the general 31 public do not have access to edible vegetation at the nursery site. 32 As summarized in Worksheet E05, none of the HQs for cancer based in an incremental risk 34 associated with a single exposure for 1 day exceeds the level of concern. Most HQs are far 35 below the level of concern. One notable exception is the scenario for the consumption of 36 contaminated vegetation, which result in HQs of 0.02 (0.00005 to 0.4). The upper bound HQ of 37

0.4 indicates that the consumption of contaminated vegetation might lead to a cancer risk in 38 excess of 1-in-1-million over an exposure period greater than 2.5 days [1 ÷ 0.4 day-1]. As above, 39 concerns for the upper bound HQ can be mitigated by ensuring that members of the general 40 public do not have access to edible vegetation at the nursery site. 41

4. ECOLOGICAL EFFECTS 1

4.1. Hazard Identification 2

As with the hazard identification for human health (Section 3.1), the hazard identification for 3 ecological effects is highly abbreviated in the current document. The overall database for 4 ecological effects is discussed in detail in U.S. EPA/OPP/EFED (2010), the most recent 5 ecological risk assessment on oryzalin. Specific toxicity values for different groups of receptors 6 are discussed in Section 4.3. 7 Oryzalin is a dinitroanaline herbicide that inhibits microtubule assembly in plants and is in the 9 same chemical class as herbicides such as trifluralin (SERA 2011d). Oryzalin is absorbed by 10 roots but is not well-absorbed by leaves and is not translocated in plants (NMFS 2012). The 11 effect of oryzalin on microtubules is limited to plants does not affect microtubules in animals 12 (U.S. EPA/OPP/EFED 2010, p. 34; NMFS 2012, p. 444). In terms of the potential for resistance, 13 oryzalin is classified as WSSA Group 7, HRAC Group K1 (Mallory-Smith and Retzinger 2003). 14 No metabolites of oryzalin are classified as metabolites of concern (U.S. EPA/OPP/EFED 2010, 15

p. 15). 16

4.2. Exposure Assessment 17

4.2.1. Bioconcentration 18

Typically, bioconcentration values for whole fish are used in the ecological risk assessment, and 19 bioconcentration factors for the edible portion of fish (i.e., muscle) are used in the human health 20 risk assessment. As discussed in Section 3.2.2.3, very little information is available on the 21 bioconcentration of oryzalin—i.e., a single estimate of 66 L/kg in whole fish from based on a 22 registrant-submitted study (U.S. EPA/OPP 1994a, p. 29, MRID 40787501). In the absence of 23 additional information, this BCF is applied to both acute and longer-term exposure scenarios 24 involving the consumption of contaminated fish by wildlife. 25

4.2.2. Offsite Contamination of Soil 26

Rates for the offsite contamination of soil are typically handled in full or scoping level Forest 27 Service risk assessments using GLEAMS-Driver modelling. In the interest of economy, the 28 current effort uses a central estimate of 5% with a range of 1% to 10% of the nominal application 29 rate. These values are similar to estimates of offsite losses noted in Forest Service pesticide risk 30 assessments as well as assumptions often used in EPA risk assessments. 31

4.2.3. Surface Water 32

As with most full Forest Service risk assessments, the surface water concentrations used in the 33 ecological risk assessment are identical to those used in the human health risk assessment 34 (Section 3.2.1.1). 35

4.3. Dose-Response Assessment 36

The dose response assessment for nontarget organisms is summarized in Table 4 and is discussed 37 in the following subsections on different groups of receptors. 38 With the exception of mammals (as discussed in Section 4.3.1.1), Forest Service risk 40 assessments generally defer to dose-response assessments from U.S. EPA/OPP/EFED in the 41 selection of endpoints and study selection in the dose-response assessments for ecological 1 receptors, unless there is a compelling reason to do otherwise. For endpoints associated with 2 acute toxicity, however, the Forest Service prefers to use NOAECs rather than estimates of 50% 3 lethality (LD50 or LC50 values) which are used in EPA risk assessments. In the absence of an 4 NOAEC, Forest Service risk assessments use LD50 or LC50 values to approximate an NOAEC by 5 dividing the lethality value by a factor of 10 for terrestrial species or 20 for aquatic species. This 6 approach is based on and consistent with the EPA variable level of concern approach, as detailed 7 in SERA (2014, Section 4.3.2, Table 19). References to the use of this procedure are noted 8 below as appropriate. 9 The dose-response assessments presented in the following sections are taken from U.S. 11 EPA/OPP/EFED (2010). Appendix A of this EPA risk assessment provides details on some 12 studies included in the following sections. In the interest of brevity, Appendix A from U.S. 13 EPA/OPP/EFED (2010) is referenced simply as EFED Appendix A in the following sections. 14

4.3.1. Terrestrial Organisms 15

4.3.1.1. Mammals 16

For the dose-response assessment of mammalian wildlife, Forest Service risk assessments 17 typically use the acute and chronic NOAELs from the human health risk assessment that form 18 the basis of the acute and chronic RfDs. This approach is adopted for oryzalin. 19 As discussed in Section 3.3 and summarized in Table 3, the acute NOAEL is 25 mg/kg bw/day 21 from a developmental study in rabbits with a corresponding LOAEL of 55 mg/kg bw/day based 22 of fetal toxicity. Thus, for the ecological risk assessment, the NOAEL of 25 mg/kg bw/day is 23 used for oryzalin. 24 For the chronic RfD, the NOAEL used in the human health risk assessment is 14 mg/kg bw/day 26 (Table 3) with a corresponding LOAEL of 43 mg/kg bw/day based on changes in thyroid tissue. 27 Again, for the same reason noted in the selection of acute NOAEL, the NOAEL of 14 mg/kg 28 bw/day is used for risk characterization of longer-term exposures of mammalian wildlife to 29 oryzalin. 30

4.3.1.2. Birds 31

4.3.1.2.1 Acute Toxicity 32

U.S. EPA/OPP/EFED (2010, p. 82) provides two toxicity values for birds—i.e., an acute LD50 of 33

506.7 mg/kg bw via gavage (MRID 00098462) and an acute dietary LOAEL of 625 ppm (mg 34 a.i./kg food) in bobwhite quail (MRID 00072593). 35 A NOAEL for the gavage study is not specified in the main body of the EFED risk assessment or 37 in EFED Appendix A. Dividing the LD50 by 10, a surrogate NOAEL of about 50 mg/kg bw/day 38 can be estimated. This estimated NOAEL is only modestly higher than the NOAEL of 25 mg/kg 39 bw/day in mammals (Section 4.3.1.1). 40 As indicated in a previous Forest Service risk assessment for which both body weights and food 42 consumption rates in acute dietary studies were available for quail and mallards (SERA 2007b), 43 approximate food consumption rates in acute dietary studies are about 0.4 kg food/kg bw for 1 mallards and 0.3 kg food/kg bw for quail. These food consumption rates are from standard 2 studies using very young birds. Using a food consumption rate of 0.3 chow/kg bw quail, the 3 acute dietary LOAEL of 625 mg/kg chow corresponds to dose of 187.5 mg/kg bw/day [625 4 mg/kg chow x 0.3 chow/kg bw/day ≈187.5 mg /kg bw/day]. Dividing the LOAEL by a factor of 5 10, the NOAEL is approximated as 18.75 mg/kg bw/day. This estimated NOAEL is only 6 modestly lower than the NOAEL of 25 mg/kg bw/day in mammals (Section 4.3.1.1). 7 For the current analysis, the lower NOAEL of 18.75 mg/kg bw/day is rounded to 19 mg/kg 9 bw/day and is used as the basis for characterizing acute risks for birds exposed to oryzalin. 10

4.3.1.2.2 Chronic Toxicity 11

To characterize risks to birds associated with longer-term exposures to oryzalin, U.S. 12 EPA/OPP/EFED (2010, Section 4.2.1.2, p. 83) uses a NOAEL of 132 mg/kg chow from a 13 reproductive study in quail (MRID 44162201). The corresponding LOAEL is 311 mg/kg chow 14 based on reduced body weight in females. Using a food consumption rate of 0.07 chow/kg bw 15 for longer-term studies in quail and mallards (SERA 2007b), the dietary NOAEL of 132 mg/kg 16 chow corresponds to dose of about 9 mg/kg bw/day [132 mg/kg chow x 0.07 chow/kg bw/day = 17

9.24 mg /kg bw] with a corresponding LOAEL of about 22 mg/kg bw/day [311 mg/kg chow x 18

0.07 chow/kg bw/day = 21.77 mg /kg bw]. Thus, for the current analysis, the NOAEC of 9 19 mg/kg bw/day is used to characterize risks associated with longer-term exposures of birds to 20 oryzalin. As with acute toxicity, the estimated NOAEL of 9 mg/kg bw/day in birds is similar to 21 the estimated NOAEL of 14 mg/kg bw/day in mammals (Table 4). 22

4.3.1.3. Amphibians, Terrestrial-Phase 23

Data on terrestrial-phase amphibians are not summarized in the EFED risk assessment, and birds 24 are used as surrogates for terrestrial-phase amphibians (U.S. EPA/OPP/EFED 2010, p. 52). The 25 Pauli et al. (2000) compendium of toxicity studies in reptiles and amphibians does not include 26 information on oryzalin. Furthermore, the toxicity of oryzalin to amphibians is not addressed in 27 the NMFS (2012) assessment. 28

4.3.1.4. Honey Bee 29

U.S. EPA/OPP/EFED (2010, p. 84 and Appendix A, Table A-8) summarizes a single study in the 30 honeybee in which the acute contact LD50 is reported as >11 µg/bee. It is not clear if the 31 indefinite LD50 represents a NOAEL or a dose associated with partial mortality. This study is 32 used to classify oryzalin as …practically non-toxic to honeybees on an acute contact basis. This 33 toxicity value is not used by EFED to characterize risks to terrestrial insects because the LD50 is 34 indefinite (U.S. EPA/OPP/EFED 2010, p. 100). This approach is adopted in the current 35 assessment, and risks to honeybees are not quantified. 36

4.3.1.5. Terrestrial Plants 1

As with most herbicides, a standard set of toxicity studies on monocots and dicots involving both 2 seedling emergence (soil applications) and vegetative vigor (foliar applications) are available for 3 oryzalin (U.S. EPA/OPP/EFED 2010, Appendix A, Table A-9, MRID 426024-01). 4 Based on reported NOAECs for foliar exposure, the most sensitive species are ryegrass 6 (monocot), lettuce (dicot), and tomato (dicot), all with NOAECs of 0.0253 lb a.i./acre. The most 7 tolerant species are onion (monocot) and soybean (dicot), each with NOAECs of 2 lb a.i./acre. 8 For soil application, the most sensitive species is tomato (dicot) with an EC05 (a functional 10 NOAEL) of 0.0056 lb a.i./acre. The most tolerant species is soybean (another dicot) with an 11 NOAEL of 6 lb a.i./acre. 12 The lower NOAECs for soil exposures, relative to foliar exposures, is consistent with the 14 assessment in the EFED risk assessment that oryzalin is not well-absorbed by leaf surfaces 15 (Section 4.1). 16 The EFED assessment does note the following cautionary language required on the formulation 18 labels for oryzalin. 19

The labels for oryzalin caution not to apply this herbicide to Douglas fir, slender 21 deutzia, Techny arborvitae, eastern hemlock, begonia, and coleus due to 22 phytotoxicity on the above species. 23

U.S. EPA/OPP/EFED (2010, p. 34). 24 It is not clear if the NOAECs for sensitive species of plants from MRID 426024-01encompass 26 the species listed above. The EFED risk assessment does not provide a summary of the open 27 literature on the toxicity of oryzalin to terrestrial plants. While the open literature on oryzalin is 28 not extensive (Section 1.2), it may contain information relating to the cautionary language 29 required on oryzalin formulations. 30

4.3.2. Aquatic Organisms 31

As discussed in the following sections, most acute toxicity values are reported in U.S. 32 EPA/OPP/EFED (2010) in units of mg/L, the same units used in the WorksheetMaker workbook 33 that accompanies this report. For aquatic plants, however, some toxicity values are given by 34 EFED in units of µg/L. To maintain consistency with the EPA source document, the units for 35 concentration in the following sections are identical to those used by EFED. All toxicity values 36 used in the WorksheetMaker workbook as well as Table 4, however, are also expressed in units 37 of mg/L. 38 Forest Service risk assessments attempt to develop toxicity values for both tolerant and sensitive 40 species, and this approach is used in the current document.