2

Data Gaps

Fate Data

Based on the PPO us e patt ern as a fumigant and its chemical propert ies

, EFED will not request the fate data at this time but will use any available data requested by the Agency’s Health Effect s Division

, such as field monitoring data

, at the time of registration review risk asses sment.

Ecological Effect Data

The ecological effect s database is considered incomplete for risk assessment. EFED recommends submission of the following studies. Details of the data gaps are discussed further

in Section 6.8

.

Avian Acute Inhalation Toxicity Study (A Non

- Guideline Study): Propylene oxide has fumigant uses that may result in exposure to birds. The acute effects to birds exposed

to PPO are unknown. This is a non

- guideline study under the 40 CFR Part 158 data requirements.

Honeybee Ac ute Vapor Exposure Toxicity Study (A Non

- Guideline Study): Propylene oxide has fumigant uses that may result in exposure to honeybees. The toxicity of PPO to honeybees is unknown. This is a non

- guideline study under the 40 CFR Part 158 data requirements.

Terrestrial Plants Special Study

– Vegetative Vigor Vapor Exposure Toxicity Study ( A N on

- guideline Study ): Propylene oxide has fumigant uses that may result in exposure to terrestrial plants. Knowledge of t he toxicity of PPO to terrestrial plants is limite d to soybean (MRID 4791701) data that ha ve been submitted to the Agency, which partially satisfies the Agency’s data requirements for toxicity testing with terrestrial plants. Data

on f our monocots in two families including corn

, six dicots species in four families including soybean and a root crop

, is needed to completely assess the alkylating effects of PPO to terrestrial plants. This is a non

- guideline study under the 40 CFR Part 158 data requirements.

Label Uncertainties

There are uncertainties in t he usage of PPO i n treatment facilities including the maximum

number of chamber s , frequency of treatment and type of emision control devi c e. The s e factors will directly influence emission rates and affect outdoor air concentrations. In addition, there is a lack of information related to the design of buildings for the fumigation, including the dimensions of buildings, type of buildings, as well as the number and relative locations of stack and vents that serve as the release points during PPO aeration ope rations. These variables all impact the magnitude of downwind dispersion from treated structures

. EFED recommends label

amendments to be made to clarify the above uncertainties.3



# Problem Formulation for the Environmental Fate, Ecological Risk, Endangered Species, and Drinking Water Exposure Assessm ents in Support of the Registration Review of Propylene Oxide

CAS: 75

- 56

- 9

PC Code: 042501

Environmental Fate and Effects Division Prepared by:

Ste phen Carey, Biologist He Zhong , Ph.D., Biologist U.S. Environmental Protection Agency Office of Pes ticide Programs Environmental Fate and Effects Division

Environmental Risk Branch I 1200 Pennsylvania Ave., NW

Mail Code 7507P Washington, DC 20460 Reviewed by:

Michael Lowit , Ph.D., Ec ologist

S tephen Wente , Ph.D., Fate Scientist4



### Table of Contents

1. Purpose

................................ ................................ ................................ ................................ .... 5

2. Problem Formulation

................................ ................................ ................................ .............. 5

2.1. Nature of Regulatory Action

................................ ................................ ........................ 5

2.2. Previous Assessments

................................ ................................ ................................ ... 5

2.2.1. Ecological Risk Assessments

................................ ................................ ................... 5

2.2.2. Dr inking Water Exposure Assessments

................................ ................................ ... 5

3. Stressor Source and Distribution

................................ ................................ ............................ 5

3.1. Mechanism of Action

................................ ................................ ................................ ....... 5

3.2. Overview of Pesticide Use and Usage

................................ ................................ ............. 6

3.3. Chemical and Physical Properties, and Environmental Fate and Transport

.................... 7

3.4. Clean Water Act

................................ ................................ ................................ ............. 11

4. Receptors

................................ ................................ ................................ ................................ .. 11

4.1. Effects to Aquatic Organisms

................................ ................................ ........................ 11

4.2. Effects to Terrestrial Organisms

................................ ................................ .................... 12

4.3. Incident Databases Review

................................ ................................ ............................ 13

5. Exposure Pathways of Concern

................................ ................................ ............................... 13

6. Analysis Plan

................................ ................................ ................................ ........................... 14

6.1. Stressors of Concern

................................ ................................ ................................ .......... 15

6.2. Measures of Exposure

................................ ................................ ................................ ........ 15

6.3. Measures of Effect

................................ ................................ ................................ ............. 15

6.4. Integration of Exposure and Effects

................................ ................................ .................. 16

6.5. Endangered Species Assessments

................................ ................................ ...................... 16

6.6. Endocrine Disruptor Screening

................................ ................................ .......................... 16

6.7. Drinking Water Assessment

................................ ................................ .............................. 16

6.8. Preliminary Identification of Data Gaps

................................ ................................ ............ 16

6.8.1. Environmental Fate Data

................................ ................................ ............................ 17

6.8.2. Ecol ogical Effects Data

................................ ................................ ........................... 17

References

................................ ................................ ................................ ................................ ..... 24

Appendix I

................................ ................................ ................................ ................................ .... 26

Appendix II

................................ ................................ ................................ ................................ ... 325

1. Purpose

The purpose of this problem formulation is to provide an understanding of what is known about the environmental fate, ecological effects, and currently registered uses of propylene oxide (PPO) (or 1,2

- propylene oxide o r epoxypropane) as a fumigant. This document provides a plan for analyzing data relevant to PPO and for conducting environmental fate, ecological risk, endangered species, and drinking water exposure assessments for its registered uses. Additionally, thi s problem formulation identifies data gaps, uncertainties, and potential assumptions used to address those uncertainties relative to characterizing the potential ecological risk associated with the registered uses of PPO.

2. Problem Formulation

2.1. Natu re of Regulatory Action

As part of the implementation of the new Registration Review program 1 pursuant to Section 3(g) of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), the Agency is beginning its

evaluation of PPO to determine whether it continues to meet the FIFRA standard for registration. This problem formulation in support of the registration review of PPO will be posted in the initial docket which will open the public phase of the review process.

2.2. Previous Assessments

2.2.1. Ecological Risk Assessments

The Agency’s p revious risk assessment for PPO concluded that there are likely no concerns for acute lethality or reproduction impairment in terrestrial mammals, repti les, terrestrial phase amphibians, fish and aquatic invertebrates (USEPA 2006)

. For plants, t here wa s insufficient

information to preclude the potential concern that PPO may pose risks to terrestrial and aquatic plants ; thus, the risks could not be preclu ded

. Risk to terrestrial invertebrates is uncertain.

2.2.2. Drinking Water Exposure Assessments

A drinking wat er assessment (DWA) has not been conducted for PPO.

3. Stressor Source and Distribution

As a fumigant, PPO is formulated as a pressurized liquid and/or gas used in chambers for the sterilization of packaged food and as a post

- harvest treatment for agricult ural commodities. Two degradates

, chloropropanol and 1,2

- propanediol

, were identified in open literature data

.

3.1. Mechanism of Action

PPO is a fumigant used as an insecticide to control insect infestations. It is also used as sterilant to prevent bacteria, mold contamination, and microbial spoilage for food and nonfood products (USEPA 2006). PPO has been shown to cause central nervous system effects such as ataxia,

un coordination, and depression in rats ( Propylene Oxide by Dow

, accessed 3/18/2013)

.

1 http://www.epa .gov/oppsrrd1/registration_review/6

( http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_0036/0901b80380036c15.pdf?fi lepath=propyleneoxid e/pdfs/noreg/117

- 01641.pdf&fromPage=GetDoc ). Occupational Safety &

Health Administration (OS HA ) established PPO permissible exposure limit (PEL) as 100 ppm and the vapor can affect eyes, skin and respiratory system https://www.osha.gov/dts/chemicalsampling/data/CH_265000.html (accessed 5/7/2013). PPO is a possible carcinogen, mutagen, and teratogen in animals and human s

.

3.2. Overview of Pesticide Use and Usage

PPO is registered for both agricultural and non

- agricultural use according to the Biological and Economic Analysis Division (BEAD ) (USEPA 2012). It can be used in sealed chamber s ( Propylene Oxide Fumigant with 100% a.i.) or in non

- sealed structures including trailers,

containe rs, rail cars, tarped materials and tents (Propoxide 892 with 8%, a.i.) for agricultural commodities: processed food/feed stored products (raisins, grapes, plums, prunes/figs, cocoa beans, cocoa powder, spices, birdseed, processed nuts) and non

- agricultura l sites: transportation vehicles, empty containers (processed feed/food, raw agricultural commodities feed/food), airtight chambers, shipping commercial transportation (containers, empty trailers, empty railroad

boxcars feed/food), pharmaceutical materials , tents, and vaults. PPO is formulated as a pressurized gas. The maximum application rate is 150 lb a.i./1000 ft 3 (or 24 oz a.i./ft 3 ) in a sealed chamber ( Table 1 ). In addition, it is also used at a concentration of 8% with an inert gas (carbon dioxide, nitrogen) for figs, dried plums (prunes), and raisins (USEPA 2012). PPO is only used for processed food/ feed stored products.

T he California Department of Pesticide Regulation (CDPR) reported that in 2010, a total of 300,000 lb of PPO was used for cr ops in California, the 57th most used pesticide (by pound) (USEPA 2012)

. EPA has estimated 64.8 million pounds of commodities were treated with PPO annually and the usage is mostly on nutmeats ( ~ 1.8% treated) and spices ( ~ 1% treated) (USEPA 2006)

. Table 1. Maximum Rates for Registered uses of Propylene Oxide

Use Method of

Application Single M aximum

Application Rate (lb a.i. /1,000 ft

3 ) Allowable Release

Conditions EPA Reg No.

Sealed

Chamber 1 Fumigation 150 5 ft stack with

emission control 47870

- 1

47870

- 3

Sealed

Chamber 2 Fumigation 75 27 ft stack with 20
air changes per hour 47870

- 1

47870

- 3

Sealed

Chamber 2 Fumigation 75 40 ft stack with 4 air
changes per hour 47870

- 1

47870

- 3

Other

Structure s 3 Fumigation 2.8 None Specified 47870

- 3

1 The chamber ( >5,000 ft 3 and ≤ 10,000 ft 3 ) must be equipped with equipment specifically designed to reduce PPO emissions by at least 95%.

2 For chambers <5,000 ft 3 , 4 air changes per hr for 40 ft stack or 20 air changes per hr for 27 ft stack are required.7 3 Others include: atmos pheric chambers, structures, tents, tarped product, rail cars or shipping containers. The

PPO level in the enclosure is measured to be 10 ppm or less.

3.3. Chemical and Physical Properties, and Environmental Fate and Transport

PPO is a colo rless liquid tha t is highly volatile and flammable at room temperature and normal atmospheric pressure (USEPA 2006). PPO vapor is highly reactive and may form an explosive

mixture with air

. The compound can be removed from the atmosphere by slow oxidation and by

rain. It evaporates from water and is not expected to bioaccumulate. PPO may polymerize with chlorine, ammonia, strong oxidants, and acids. The compound ring opening occurs in reactions with nucleophiles, such as water, alcohols, amines, halides, and sulfhydry l compounds. There are two reaction products formed during the PPO sterilization process

– propylene chlorohydrin (PCH ) and propylene bromohydrin (PBH). PCH contains two isomers, 1

- chloro 2

- propanol (75%) and 2 chloro

- 1propanol (25% )

. In addition to PPO , PCH is considered to be a residue of concern for dietary risk assessment purposes because residues persist at high levels. PBH residues are minimal relative to PCH residues; therefore, PBH is not considered to be a residue of concern (USEPA 2006). The physical and chemical properties of PPO are listed in Table 2

.8

Table 2 . Physical

- chemical Properties of Propylene Oxide

Parameter Value and units Reference Comments

Chemical Propylene Oxide (PPO) USEPA 2006 ( RED)

CAS Name 1,2

- e poxypropane USEPA 2006 ( RED)

Chemical Family Fumigant USEPA 2006 ( RED)

Empirical Formula C 3 H 6 O 1 USEPA 2006 ( RED)

SMILES CC1CO1 EPI V4.10

CAS Number 75

- 56

- 9 USEPA 2006 ( RED)

Structure USEPA 2006 ( RED)

Molecular Weight 58.08 (g/mole) EPI V4.10

Density 0.83 g /ml, (20 °C) U S EPA 2006

Vapor pressure 440 mm Hg ( 2 0 oC) U S EPA 2006

Henry’s law constant 6.96E

- 05(atm·m 3 /mol @ 25°C) EPI V4.10

Water Solubility 39.5 g/100m L ( 2 0 oC) U S EPA 2006

Octanol

- water partition coefficient (Kow) 0.03 ( 25°C ) U S EPA 2006

A ir

- water partition coefficient

- 2.546 (Log Kaw) EPI V4.10

Octanol

- air partition coefficient 2.576 (Log Koa) EPI V4.10

Melting point

- 104( °C) IPCS 1

Boiling point 34( °C) IPCS

Flash point <

- 37( °C) IPCS

Flammable limits 2

- 37% by volume IPCS

Log K ow 0.13 IPCS

Reaction Products

1,2

- propanediol

CAS No: (57

- 55

- 6)

Molecular Formula : C 3 H 8 O 2 Mass: 76.09 g/mol SMILES: CC(O)CO EPI V4 .10

&

USEPA 2006 ( RED) (also called propane

1,2

- diol, or Propylene glycol)

Chloropropanol

CAS No: 96

- 24

- 2

Molecular Formula : C 3 H 7 ClO 2 Mass: 110.539 g/mol SMILES: ClCC(O)CO EPI V4.10

&

IPCS (also called 3

-

MCPD, 3

- monochloropropane

1,2

- diol or 3

- chloropropane

- 1,2

- diol)9

Table 2 . Physical

- chemical Properties of Propylene Oxide

Parameter Value and units Reference Comments

Propylene chlorohydrin (PCH)

1

- chloro 2

- propanol (75%)

CAS No: 78

- 89

- 7

Molecular Formula:C 3 H 7 ClO

Mass: 94.54 g/mol

SMILES: CC(O )C Cl EPI V4.10

&

USEPA 2006 ( RED)

Propylene chlorohydrin (PCH)

2 chloro

- 1propanol (25%)

CAS No: 78

- 89

- 7

Molecular Formula:C 3 H 7 ClO

Mass: 94.54 g/mol

SMILES: CC(Cl)CO EPI V4.10

&

USEPA 2006 ( RED)

1 International Programme on Chemical Safety (IPCS). Environmental Health Criteria Monographs. Available at http://www.inchem.org/documents/ehc/ehc/ehc56.htm (Accessed 2/27/2013).

IPCS offered the following formula to convert gas concentration in cubic air (mg/m 3 ) into part s per million (ppm):

Conversion Factor: 1 ppm = 2.37 mg/m 3 air at 25 °C and 101.3 kPa (760 mm Hg)

PPO enters the environment mainly through release of vented gases during /after the applica tion

. Bogyo et al. (1980) reported that m ost of the applied PPO fumigant enter s the atmosphere. A previous estimated total PPO loss to the atmosphere was about 600 ton n es , which is approximately 0.07% of total PPO production in the USA (Storck, 1981; US EPA, 1981).

The entire suite of fate studies described under the 40 CFR 158 data requirements have not been

submitted to the Agency by the registrant ( Table 3 ). This was the result of assuming indoor fumigation did not result in significant concentrat ions of PPO outside of the fumigated enclosure.
However, labeled uses associated with the Propoxide 892 product do not entirely fall within the indoor uses category. These uses include rail cars, tented areas, tarped materials, and in

- field

treatment cha mbers. The previous ecological risk assessment addresses risks associat ed with the Propoxide 892 uses and t he expected environmental concentrations (EECs ) of PPO in terms of

“a ir concentration of concern” were established by the Probabilistic Exposure and Risk Model for Fumigants model (PERFUM model ) as 2.42 g/m 3 for acute non

- listed and listed species (USEPA 2006)

. An open literature review suggests that a major ity of PPO will be rapidly

removed from the atmosphere via hydroxyl radical oxidation. On the basis of a theoretical rate constant for this reaction, the atmospheric residence time of PPO was calculated to be 8.9 days (Cupitt, 1980)

. Because of its high solubility in water ( 395 g/L, Table 2 )

, PPO levels in air can also be reduced via washout by ra in (Bogyo et al., 1980). No data were found concerning the

rate of volatilization of PPO from water. However, PPO ’s half

- life was estimated to be > 1 h our (Conway et al., 1983). Chemical degradation in water via ionic reactions appears a slow process

und er environmental conditions. In neutral fresh water and catalyzed by acid at 25 °C, PPO will react to form 1,2

- propanediol with a half

- life of approximately 12 days (Koskikallio & Whalley, 1959). In neutral marine water, there is a preference for the for mation of 1

- halopropan

- 2

- ol10

(Addy & Parker, 1963). Bogyo et al. (1980) estimated approximately 80% of the PPO present
will react with chloride to form chloropropanol; the remainder will react with water to form 1,2

- propanediol at 25 °C in neutral sea wate r of 3% salinity . The overall half

- life with respect to these reactions is 4 days , but actual retention time in water may only be in few hours due to

volatilization (Conway et al., 1983)

.

Microorganisms were found to degrade PPO very slowly. The biologi cal oxygen demand (BOD) over 5 days was 8% of the theoretical oxygen dem and (Bridié et al., 1979 ). Bont et al. (1982)

found the first step in bacterial metabolism is the conversion of propylene oxide to 1,2

- propanediol by epoxide hydrolase, followed by de hydration and oxidation .

Table 3. Environmental Fate of Propylene Oxide

Parameter Value Reference

Hydrolysis (t 1⁄2 @ 25oC, pH 7) 3.6 days Bogyo et al., 1980

Aqueous Photolysis (t 1⁄2 ) No Data

Soil Photolysis (t 1⁄2 ) No Data

Aerobic Soil Metabolis m (t 1⁄2 ) No Data

Anaerobic Aquatic Metabolism (t 1⁄2 ) No Data

Aerobic Aquatic Metabolism (t 1⁄2 ) No Data
Bioconcentration / Depuration (t 1⁄2 ) No Data
Mobility

Koc 7.097 ( mL/g) EPI V4.10

Field Dissipation

Terrestrial Field Dissipation (t 1⁄2 ) No D ata

Volatilization (t 1⁄2 from Model River) 7.189 hrs EPI V4.10

Reaction Products

1,2

- propanediol (in neutral fresh water and catalyzed by acid at 25 °C) 50% PPO formed 1,2

- propanediol in 12 days Koskikallio & Whalley, 1959

Chloropropanol (in neutral sea water of 3% salinity at 25 °C) 80% of the PPO will react with chloride to form chloropropanol;

the remainder will react with water to form 1,2

- propanediol.

The overall half

- life is 4 days. Bogyo et al. 198011

3.4. Clean Water Act

PPO is not identified as a cause of impairment for any water bodies listed as impaired under section 303(d) of the Clean Water Act 2 . In addition, total maximum d aily l oads (TMDL) have

not been developed for this fumigant 3 . The Impaired Waters and TMDL website can be

consulted for more information 4 . The Agency invites submission of water quality data for PPO. To the extent possible, data should conform to the quality standards in the OPP Standard Operating Procedure: Inclusion of Impaired Water Body and Other Water Quality Data in OPP’s Registration Review Risk Assessment and Management Process 5 , in order to ensure they can be used quantitatively or qualitatively in pesticide risk assessments.

4. Receptors

Tables 4 and 5 provide a summary of the aquatic and terrestrial taxonomic groups, respectively, and most sensitive surrogate species tested to characterize the potential acute and chronic ecological effects of PPO

. In addition, the tables provide a preliminary overview of the potential acute toxicity of PPO by providing the acu te toxicity classifications. In the absence of effects data for PPO, information sources from other alkylene oxides (e.g., ethylene oxide (ETO) which is structurally similar to PPO) have been useful in approximating the ecological effects of PPO.

4.1. Effec ts to Aquatic Organisms

Table 4. Summary of the Most Sensitive Endpoints from Aquatic Toxicity Studies for PPO

Taxonomic Group Study Type Surrogate Species Toxicity Value (mg a.i./L) Acute Toxicity

Classification

or Adverse

Effect

Observed Source

(Stu dy classification)

Freshwater fish 1 Acute Fathead minnow ( Pimephales promelas ) LC 50 = 84 Slightly toxic Conway et al,

1983 2

Chronic No data available.

Freshwater

invertebrates Acute Water Flea ( Daphnia magna ) EC 50 = 137 Practically non

toxic Conway et al,

1983 2

Chronic No data available.

Estuarine/marine

fish Acute Striped mullet ( Mugil cephalus ) LC 50 = 89 Slightly toxic Crews et al, 1974

Chronic No data available.

Estuarine/marine

invertebrates Acute Brine shrimp ( Artemia sp. ) EC 50 = 490 Pract ically non

toxic Conway et al,

1983 2

Chronic No data available. Aquatic plants and algae Vascular Duckweed ( Lemna gibba ) EC 50 >0.87

NOAEC = 0.87 -- a MRID 47921702 (Acceptable) b

2 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885

3 http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant_ group_name=PES TICIDES

4 http://www.epa.gov/owow/tmdl/

5 http://www.epa.gov/oppfead1/cb/ppdc/2006/november06/session1

- sop.pdf12

Table 4. Summary of the Most Sensitive Endpoints from Aquatic Toxicity Studies for PPO

Taxonomic Group Study Type Surrogate Species Toxicity Value (mg a.i./L) Acute Toxicity

Classification

or Adverse

Effect

Observed Source

(Stu dy classification)

Non

- vascular Freshwater green

alga

Pseudokirchnerie lla subcapitata EC 50 >0.86

NOAEC= 0.86 -- a MRID 47921703 (Acceptable) b

1 Freshwater fish may be surrogates for aquatic

- phase amphibians.

2 ETO data

a Toxicity categories have not been defined.

b The studies were modified to accommodate a volatile substa nce by using environmental chambers to maintain the air concentration of the gas.

4.2. Effects to Terrestrial Organisms

Table 5. Summary of the Most Sensitive Endpoints from Terrestrial Toxicity Studies for PPO

Taxonomic Group Study

Type Surrogate

Species T oxicity Value Acute Toxicity

Classification or

Adverse Effects

Observed Source

(Study classification)

Birds 1 Acute

Inhalation 2 upland game

bird and

waterfowl LD 50 = no data N/A N/A

Chronic NOAEC = no data

LOAEC = no data N/A N/A

Mammals Acute

Inhalation Laboratory

mice LD 50 = 2420 mg a.i./m 3 Category IV NTP, 1985

Chronic Laboratory rat

( Rattus norvegicus ) NOAEL = 720 mg a.i./m 3

LOAEL >720 mg a.i./m 3
Affected Reproduction/Offs pring Endpoint:

None 45292701 (Acceptable) b NOAEL = 240 mg a.i./m 3
LOAEL = 720 mg a.i./m 3
Affected Parental Endpoint: Decreased body weights and weight gain

Terrestrial

invertebrates Acute Rust

- red flour

beetle ( Tribolium

castaneum ) LD 50 = 1000 mg a.i./m 3

-- a Navarro et al, 2004

Beneficial

i nsects Acute

Contact Honey bee

( Apis mellifera

L. ) LD 50 = no data N/A N/A

Terrestrial plants Seedling

Emergence Dicot EC 50 = no data

NOAEC = no data -- a

N/A

Monocot EC 50 = no data

NOAEC = no data -- a

Vegetative Vigor Dicot

(soybean) EC 50 > 252 mg a.i./m 3

NOAEC = 252 mg a.i./m 3 -- a 47921701 (Acceptable) b

Monocot EC 50 = no data

NOAEC = no data -- a N/A13

Table 5. Summary of the Most Sensitive Endpoints from Terrestrial Toxicity Studies for PPO

Taxonomic Group Study

Type Surrogate

Species T oxicity Value Acute Toxicity

Classification or

Adverse Effects

Observed Source

(Study classification)

1 Birds represent surrogates for t errestrial

- phase amphibians and reptiles.

2 A non

- guideline acute avian inhalation toxicity study.

a Toxicity categories have not been defined.

b The studies were modified to accommodate a volatile substance by using environmental chambers to maintain the air concentration of the gas.

4.3. Incident Databases Review

The ecological incident information system (EIIS) is an OPP database that houses ecological incidents that have been reported to the Agency. When available, EIIS includes date and

location of an in cident, type and magnitude of effects observed in various species, use(s) of pesticides known or suspected of contributing to the incident, and results of any chemical residue analysis or other analyses conducted during incident investigation. EIIS incide nts are categorized according to the certainty that the incident resulted from pesticide exposure. The Avian Monitoring System (AIMS) is a database administered by the American Bird Conservancy that contains publicly available data on reported avian incid ents involving pesticides. Many of

the incidents listed in this database are also in the EIIS.

There are no reported incidents for PPO in the EIIS or AIMS databases, as well as no reports of aggregate incidents as of April 2013

. The absence of reporte d incidents should not be construed

as the absence of incidents. Incident reports for non

- target organisms typically provide information only on mortality events and plant damage. Sublethal effects in organisms such as abnormal behavior, reduced growth a nd/or impaired reproduction are rarely reported, except for some phytotoxic effects in terrestrial plants. EPA's changes in the registrant reporting requirements for incidents in 1998 may also account for a reduced number of reported incidents.

5. Expos ure Pathways of Concern

For the purposes of this risk assessment, terrestrial non

- target organisms are assumed to occupy areas immediately adjacent to treatment sites

. For a gaseous pesticide released from a treatment chamber, tarped material, or rail car , the terrestrial exposure pathway considered most likely to occur to terrestrial animals is via inhalation of the gas

, and to terrestrial plants is via contact of the gas to the external layer of plant tissues.

AERSCREEN, an air screening model, was us ed for preliminary estimation of the releasing fumigant concentration after the sterilization near the treatment facility ( http://www.epa.gov/scram001/dispersion_screening.htm )

. The model estimates the "worst

case" 1

- hour concentrations for a single source, without the need for hourly meteorological data. AERSCREEN is intended to produce concentration estimates that are equal to or greater than the estimates produced by other refined air d ispersion model s with a fully developed set of meteorological and terrain data, but the degree of conservatism may vary depending on the application. A ccording the current label at 150 lb/1000 ft 3 on an estimated treatment facility with

10 ,000ft 3 spaces
, t he maximum concentration resulting from a one

- hour release from one fumigation chamber is 16.77 g/m 3 from scenario 3 (Table 6)

. If the facility has 95% emission14

control, the maximum concentration will be reduced to 840 mg/ m 3

. The detailed modeling

info rmation can be found in Appendix I ( Modeling Input based on PPO Release Scenarios Specified on Label s ) and Appendix II ( Output Example of AERSCREEN Estimated Environmental Concentrations (EECs) for PPO Release Scenario 3 )

.

Table 6. AERSCREEN Modeling S cenarios and Data Summary

Maximum 1

- Hr Conc (μ/m 3 ) Scaled 3

- Hr

Conc (μ/m 3 ) Scaled 8

- Hr

Conc (μ/m 3 ) Scaled 24

- Hr

Conc (μ/m 3 ) Scaled Annual

Conc (μ/m 3 )
Scenario 1
Stack Height 40

ft with 4 air exchanges per

hour 0.2840E+07 0.2840E+07 0.2556E+07 0. 1704E+07 0.2840E+06

Scenario 2
Stack Height 27

ft with 20 air exchanges per

hour 0.1161E+07 0.1161E+07 0.1045E+07 0.6964E+06 0.1161E+06

Scenario 3
Stack Height 5 ft

with 1 air exchange per hour 0.1677E+08 0.1677E+08 0.1509E+08 0.1006 E+08 0.1677E+07

The aquatic exposure pathway to aquatic organisms is by uptake of the gas via gill or integument when PPO is introduced to surface water during precipitation events

, where the gas dissolves in the precipitation. Ho wever, PPO’s potential to reach water bodies will be limited by its overall atmospheric residence time of 8.9 days. In addition, rapid hydrolysis (t 1/2 = 3.16 days) and expected rapid volatilization from water is expected to limit PPO exposures once reach ing water

bodies. Therefore, acute and chronic effects to fish and aquatic invertebrates do not appear to be of concern (USEPA 2006).

6. Analysis Plan

No environmental fate data consistent with studies outlined in 40 CFR , Part 158 have been submitted

for PPO

. Limited ecological effects data have been submitted for PPO; however, more studies are needed to fulfill the 40 CFR Part 158 data requirements for fumigant uses.

In order to assess potential risks to the n on

- target organisms when expo sed to PPO , the potential

for adverse effects on the environment will be assessed by estimat ing air concentration s adjacent to the treatment facility through the use of dispersion model s ( Fig. 1 ) . The quantity of air

emission s via modeling, submitted ecol ogical effect data and ECOTOX database information will be integrated to assess the potential risk. This will be accomplished by determining a risk quotient (ratio of exposure concentration to effects concentration) for a given use . Although risk

is ofte n defined as the likelihood and magnitude of adverse ecological effects, the risk quotient

based approach does not provide a quantitative estimate of likelihood or magnitude of an adverse effect. However, as outlined in the Overview Document (USEPA, 2004c ), the likelihood of effects to individual organisms from particular uses of PPO will be estimated using the probit

dose

- response slope and either the level of concern or actual calculated risk quotient value.15

Figure 1. P roposed propylene oxide struc tural fumigant air exposure scenario for the risk

assessment.

This analysis plan may be revisited and revised depending upon a review of new available data and the information submitted by the public in response to the opening of the Registration

Review d ocket.

6.1. Stressors of Concern

The stressors of concern will be the parent compound, PPO. The re is no evidence that the reaction products, PCH, 1,2

- propanediol and c hloropropanol are formed in substantial amount in

the air for terrestrial non

- target exposure , and in water body for aquatic non

- target exposure

. B ecause of the PPO’s vola tility and short retention time in water

, an aquatic risk assessment for

PPO will not be conducted.

6.2. Measures of Exposure

PPO concentrations in air will be modeled or monitored using the maximum labeled application rates and number of app lications, the minimum application intervals, and application methods that have the greatest potential for off

- site transport . In addition, emission control requirements on PPO product labels will be considered.

PPO c oncentration s in a ir near the t reatme nt f acility will be initially estimated by a Tier

- I screening model, AERSCREEN ( http://www.epa.gov/scram001/dispersion_screening.htm ) as recommended

. The Tier

- I model will produce estimate s of "worst

- case" 1

- hour concentrations for a single source, without the need for hourly meteorological data

. Air EECs may be refined by the Tier II Probabilistic Exposure and Risk Model for Fumigants (PERFUM). PERFUM is capable of producing a distributi on of air EECs from a range of different meteorological

conditions.

6.3. Measures of Effect

Toxicity effects data will be used as measures of direct and indirect effects to biological receptors (USEPA, 2004c). As discussed previously, data will be obta ined from registrant

submitted studies and from literature studies identified in ECOTOX.

Quantitative assessment of risks will be based on study endpoints that can be directly linked to the Agency’s assessment endpoints of impaired survival, growth, and reproduction. Sub

- lethal

Treated

Structure Release Vent or Stack16

effects ( e.g. , lethargy and changes in coloration) will be evaluated qualitatively. Available

incident data will be used to further characterize risk.

6.4. Integration of Exposure and Effects

The exposure and effects data will be integrated in order to evaluate potential adverse ecological

effects on non

- target species. The risk quotient (RQ) method will be used to compare exposure and measured toxicity values. EECs will be divided by acute and chronic toxicity values. The

re sulting RQs will be compared to the Agency’s Levels of Concern (LOC) (USEPA, 2004c).

6.5. Endangered Species Assessments

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the Agency will evaluate risks to Federally

- liste d threatened and endangered (listed) species from registered uses of PPO . This assessment will be conducted i n accordance with the Overview Document (USEPA, 2004c), provisions of the ESA, and the Services’ Endangered Species

Consultation Handbook (USFWS a nd NMFS, 1998).

6.6. Endocrine Disruptor Screening

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and chronic toxicity, in cluding assessments of carcinogenicity, neurotoxicity, developmental, reproductive, and general or systemic toxicity. These studies include endpoints which may be susceptible to endocrine influence, including effects on endocrine target organ histopatholog y, organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and chronic studies that assess growth, developmental and repro ductive effects in different taxonomic groups. As part of the most recent registration decision , EPA reviewed these data and selected the most sensitive endpoints for relevant risk assessment scenarios from the existing hazard database. However, as requi red by FFDCA section 408(p), PPO is subject to the endocrine screening part of the Endocrine Disruptor Screening Program (EDSP). PPO is not in the first or second group of pesticide active ingredients to be screened under the EDSP. For

further informatio n on the status of the EDSP, the policies and procedures, the list of chemicals, the test guidelines and the Tier 1 screening battery, please visit our website: http://www.epa.gov/endo/

.

6.7. Drinking Water Assessment

PPO ’s labeled use pattern as a fumigant is unlikely to have detectable residue s for both parent and reaction products in surface water and ground water. Therefore, a DWA will not be

conducted for PPO.

6.8. Preliminary Identification of Data Gaps

Avail able studies submitted to fulfill environmental fate and ecological effects guideline requirements, as well as PPO outstanding data gaps are defined in Sections 6.8.1 and 6.8.2

, respectively. Studies are i dentified that offer data for each guideline requi rement, as well as17

study classifications and whether or not further data are needed in order to support risk

assessment.

Open literature data may not completely comply with the OCSPP guidelines which are specifically designed for results to be applied fo r a wide range of pesticides treatment uses. Nevertheless, these studies provide valuable information for risk assessment, and may be considered supplemental information for the PPO environment al fate and ecological effects profile.

T here are uncertain ties in the usage of PPO on treatment facilities, (maximum chambers or buildings), frequency of the treatment , aeration methods, air exchange exhaust rates, and the use

of emission control devi c e s . These factors will directly influence emission rates and affect outdoor air concentrations. In addition, there is a lack of information related to the design of buildings for the fumigation, including the dimensions of buildings, different size s of buildings,

as well as the number , sizes, and relative locations of stack s and vents that serve as the release points during PPO aeration operations. These variables all impact the magnitude of downwind dispersion from treated structures.

6.8.1. Environmental Fate Data

No registrant submitted data are available fo r any of the 40 CFR 158 data requirements for

environmental fate. Since exposure and resulting risk to terrestrial organisms will be directly related to the emissions of propylene oxide mass from aerated structures, environmental fate data will not be req uested at this time. EFED will use any available data requested by the Agency’s

Health Effect s Division

, such as field monitoring data

, at the time of the registration review risk

assessment.

6.8.2. Ecological Effects Data

Tables 7 and 8 identify eco logical effects studies by MRID that offer data for each guideline requirement, as well as study classifications and whether or not further data are needed in order to support risk assessment. Rationale for the additional data requested is presented below . The

studies would need to be modified to accommodate a volatile substance.

Avian Acute Inhalation Toxicity Study (A Non

- guideline Study): Propylene oxide has fumigant uses that may result in exposure to birds. The acute effects to birds exposed to

PPO a re unknown. Avian acute inhalation toxicity data were not submitted for birds exposed to PPO; however, the requested study is a non

- guideline study under the 40 CFR Part 158 data requirements. Typically, the Agency asks for avian acute oral and dietary

stu dies with an upland game bird, a passerine bird and a waterfowl to assess the acute effects to birds via the oral and dietary routes

. H owever, because PPO is a gas which is released to the atmosphere after aeration of the air

- tight chambers, the terrestria l animal exposure route considered most likely to occur is through inhalation of the gas ; the refore

the Agency is asking for a non

- guideline inhalation study with birds instead of the oral and dietary studies. Since this inhalation study is a non

- guideline study, a study protocol must be submitted for review by the Agency prior to test initiation. The preferred bird species is the Northern bobwhite quail. Until an acute inhalation endpoint to evaluate18

acute risk to birds is available, the acute risk to bird s exposed to PPO cannot be precluded and will be presumed.

Honeybee Acute Vapor Exposure Toxicity Study (A Non

- guideline Study): Propylene oxide has fumigant uses that may result in exposure to honeybees. The toxicity of PPO to honeybees is unknown. Hone ybee acute vapor

- phase exposure toxicity data were not submitted for beneficial insects exposed to PPO; however, the requested study is

a non

- guideline study under the 40 CFR Part 158 data requirements. PPO is an

insecticide which is formulated to kill ins ects , and therefore some effects to insects are expected (as observed in other terrestrial invertebrate studies)

. T he Agency is asking for a

non

- guideline vapor

- phase exposure study with bees to assess whether the effects seen in

bees are similar to what w as observed in other terrestrial invertebrates. Since this vapor

phase exposure study is a non

- guideline study, a study protocol that calculates a vapor

phase exposure LD 50 for adult bees must be submitted for review by the Agency prior to

initiation of th e study. Until an acute vapor

- phase exposure endpoint to evaluate the toxicity to honeybees is available, the acute risk to bees exposed to PPO cannot be precluded and will be presumed.

Terrestrial Plants Special Study

– Vegetative Vigor Vapor Exposure Tox icity Study ( A Non

- guideline Study ): Propylene oxide has fumigant uses that may result in exposure to terrestrial plants. Data on t he toxicity of PPO to terrestrial plants is limited to a soybean study (MRID 4791701) that has been submitted to the Agency, which partially completes the risk assessment for terrestrial plants. T esting with four monocot and six dicot species is needed to completely assess the risks to terrestrial plants, including listed species. Typically, the Agency asks for seedling emergenc e and vegetative vigor studies to assess the effects to terrestrial plants exposed to a pesticide as a result of surface water

runoff or/and off

- site spray drift, respectively; however, because PPO will be released

from air

- tight chambers as a gas, the ter restrial plant exposure pathway considered most likely to occur is through contact of the external layer of plant tissues as a result of spray drift. Instead of requesting both seedling emergence and vegetative vigor studies, the Agency is only asking for the vegetative vigor study with actively growing plants to assess the effects of PPO when the gas penetrates the plants.

To assess the potential risks to animal and plant species that indirectly rely on terrestrial plants as well as the direct risks to terrestrial plants, the study is of importance. Due to the lack of data on the range of sensitivity of terrestrial plants, the risks to terrestrial plants

, especially listed species

, exposed to PPO cannot be precluded and will be presumed. A study protoc ol must be submitted for review by the Agency prior to test initiation given the study needs to be modified to accommodate a volatile substance. The preferred plant species are four monocots in two families, including corn

, and six dicots in four families, including soybean and a root crop.19

Table 7. Submitted Aquatic Ecological Effects Data for PPO

OCSPP

Guideline Data

Requirement Submitted

Studies (MRID or Citation) Study

Classifications Are data

needed to

conduct risk

assessment? Current Additional Dat a Need

850.1010 Freshwater

invertebrate acute toxicity Conway et

al, 1983 N/A No

--

850.1025

850.1035 Estuarine/Marine

invertebrate acute toxicity Conway et

al, 1983 N/A No

--

850.1075 Freshwater fish

acute toxicity Conway et

al, 1983 N/A No

--

850.10 75 Estuarine/Marine

fish acute toxicity Crews et al,

1974 N/A No

--

850.1300 Freshwater

invertebrate life cycle (None) N/A No No reproduction data is available for freshwater invertebrates; this is a data gap. However, EFED is not asking for a chronic stu dy since significant concentrations are not expected to reach the receptors due to the rapid decline of water concentrations of the gas by the time it enter water bodies through runoff/precipitation

,

w hich results in low potential for chronic exposure.20

Table 7. Submitted Aquatic Ecological Effects Data for PPO

OCSPP

Guideline Data

Requirement Submitted

Studies (MRID or Citation) Study

Classifications Are data

needed to

conduct risk

assessment? Current Additional Dat a Need

8 50.1350 Estuarine/Marine

invertebrates life cycle (None) N/A No No reproduction data is available for estuarine/marine invertebrates; this is a data gap. However, EFED is not asking for a chronic study since significant concentrations are not expected to r each the receptors due to the rapid decline of water concentrations of the gas by the time it enter water bodies through runoff/precipitation,

w hich results in low potential for chronic exposure.

850.1400 Freshwater fish

early

- life stage (None) N/A No No reproduction data is available for freshwater fish; this is a data gap. However, EFED is not asking for a chronic study since significant concentrations are not expected to reach the receptors due to the rapid decline of water concentrations of the gas by the time it enter water bodies through runoff/precipitation, w hich results in low potential for chronic

exposure.

850.1400 Estuarine/Marine

fish early

- life

stage (None) N/A No No reproduction data is available for estuarine/marine fish; this is a data g ap. However, EFED is not asking for a chronic study since significant concentrations are not expected to reach the receptors due to the rapid decline of water concentrations of the gas by the time it enter water bodies through runoff/precipitation, w hich results in low potential for chronic

exposure.

850.1500 Fish life cycle (None) (N/A) No

--

850.4400 Aquatic plant

growth:

Tier I vascular plants 47921702 Acceptable No

--

850.4500 Aquatic plant

growth: Tier I algae 47921703 Acceptable No Only one aquati c non

- vascular species out of three species has

been submitted for OCSPP21

Table 7. Submitted Aquatic Ecological Effects Data for PPO

OCSPP

Guideline Data

Requirement Submitted

Studies (MRID or Citation) Study

Classifications Are data

needed to

conduct risk

assessment? Current Additional Dat a Need

850.4550 Aquatic plant

growth: Tier I or II cyanobacteria (None) N/A No 850.4500, while none has been

submitted for OCSPP 850.4550. This is a data gap. However, EFED is not asking for these aquatic plant studies since significant concentrations are not

ex pected to reach the receptors via

the surface water runoff route since the exposure pathway most likely to occur is via inhalation because PPO is a gas.

Table 8. Submitted Terrest rial Ecological Effects Data for PPO

OCSPP

Guideline Data

Requirement Submitted

Studies (MRID) Study

Classifications Are data

needed for

risk

assessment? Current Additional Data Need

850.2100 Avian oral

toxicity (None) N/A No No acute oral or dietary da ta is available for birds; this is a data gap. However, EFED is not asking

for these acute studies since significant concentrations are not expected to reach the receptors via the oral and dietary routes since the exposure pathway most likely

to occur to b irds is via inhalation because PPO is a gas. 850.2200 Avian dietary

toxicity (None) N/A No

850.2300 Avian

reproduction (None) N/A No No avian reproduction data is available for birds; this is a data

gap. However, EFED is not asking

for a chronic stud y since significant concentrations are not expected to reach the receptors due to the rapid decline of air concentrations of the gas which results in low potential for chronic

exposure.22

Table 8. Submitted Terrest rial Ecological Effects Data for PPO

OCSPP

Guideline Data

Requirement Submitted

Studies (MRID) Study

Classifications Are data

needed for

risk

assessment? Current Additional Data Need

Non

guideline Avian Acute

inhalation (None) (N/A) Yes An acute avian inhalation study using the Northern bobwhite quail is necessary to satisfy the toxicity profile for birds exposed
to a gas . Without data, risk would be presumed for birds, reptiles, and terrestrial

- phase amphibians, including listed species.

850.3020 Hon ey bee

acute contact toxicity (None) (N/A) No A honeybee acute contact study is not available for bees; this is a data gap. However, EFED is not asking for the contact study since significant concentrations are not expected to reach the receptors via

the o ral and contact routes since the greatest exposure pathway to honeybees is via inhalation because PPO is a gas.

Non

guideline Honeybee

acute vapor

exposure toxicity (None) N/A Yes A honeybee acute vapor exposure toxicity study is necessary to satisfy the toxicity profile for bees exposed to a gas. Without data, risk would be presumed for beneficial insects, including listed species.

850.3030 Honey bee

residue on foliage (None) (N/A) No

--

850.3040 Field testing

for pollinators (None) (N/A) No

--

850.4 100 Terrestrial

plant toxicity:

Tier I or II seedling

emergence (None) (N/A) No No seedling emergence data is available for terrestrial plants; this is a data gap. However, EFED is not asking for these data since significant concentrations of the

gas are n ot expected to reach the receptors via surface water runoff or through precipitation. Also, OCSPP guideline 850.4100 is not designed for toxicity tests with fumigants.23

Table 8. Submitted Terrest rial Ecological Effects Data for PPO

OCSPP

Guideline Data

Requirement Submitted

Studies (MRID) Study

Classifications Are data

needed for

risk

assessment? Current Additional Data Need

850.4150 Terrestrial

plant toxicity:

Tier I or II vegetative vigor (None) (N/A) No No vegetative vigor data is available for terrestrial plants; this is a data gap. However, EFED is not asking for these data since OCSPP guideline 850.4150 is not designed for toxicity tests with fumigants.

Non

guideline Terrestrial

plant special study: Tie r I or II vegetative vigor vapor

exposure toxicity 47921701 Acceptable Yes Only one dicot species out of 6 species and none of the four monocot species has been submitted; this is a data gap.

Additional data are needed to completely assess the risks to

te rrestrial plants . Without data, risk would be presumed for some terrestrial plants, including listed species.24



### References

Addy, J.K. & Parker, R. 1963. The mechanism of epoxide reactions. V. The reaction of 1,2

- epoxypropane with chloride ions in water under neutral and acidic conditions. J. Chem. Soc.,

915

- 921.

Bogyo, D.A., Lande, S.S., Meyland, W.M., Howard, P.H., and Santodonato, J. 1980. Investigation of selected potential environmental contaminants: Epoxides, Syracuse, New York, Centre for Chem ical Hazard Assessment, Syracuse Research Corporation (Prepared for US EPA) (US EPA 560/11

- 80

- 005, PB 80

- 183197).

Bont, J.A.M. De, Dijken, J.P. Van, & Ginkel, K.G. Van. 1982. The metabolism of 1,2

- propanediol by the propylene oxide utilizing bacterium Nocardia 60. Biochem. Biophys.
Acta, 714 :465

- 470.

Bridie, A.L., Wolff, C.J.M., & Winter, M. 1979. BOD and COD of some petrochemicals. Water
Res., 13 : 627

- 630.

Crews, R.C. 1974. Effects of Propylene Oxide on Selected Species of Fishes. Technical Report

No. AFATL

- TR

- 74

- 183. Environics Office, Air Force Armament Laboratory, Eglin Air Force Base, FL, 13 pp.

Conway, R.A., Waggy, G.T., Spiegel, M.H., and Berglund, R.L. 1983. Environmental fate and effects of ethylene oxide. Environ. Sci. Technol., 1 7 : 107

- 112.

Cupitt, L.T. 1980. Fate of toxic and hazardous materials in the environment, Research Triangle Park, North Carolina, USEPA, Environmental Sciences Laboratory, Office of Research and Development (US EPA 600/3

- 80

- 084, PB 80

- 221948).

Dow (online pub lication, accessed 3/18/2013). Propylene Oxide. http://msdssearch.dow.com/PublishedLiteratureDOWCOM/dh_0036/0901b80380036c15.pdf ?filepath=propyleneoxide/pdfs/noreg/117

- 01641.pdf&fromPage=GetDoc

IARC. 1976. Cadmium, nickel, some epoxides, miscellaneou s industrial chemicals and general

considerations on volatile anaesthetics, Lyons, International Agency for Research on Cancer, 293 pp (IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man, Vol. 11).

IPCS. (Accessed 2/27/2013). Int ernational Programme on Chemical Safety. Environmental

Health Criteria 56. ( http://www.inchem.org/documents/ehc/ehc/ehc56.htm )

Koskikallio, J. & Whalley, E. 1959. Effect of pressure on t he spontaneous and the base

catalysed hydrolyses of epoxides. Can. J. Chem., 37 : 783

- 787.

NTP. 1985. Toxicology and Carcinogenesis Studies of Propylene Oxide (CAS No. 75

- 56

- 9) in F344/N Rats and B6C3F1 Mice (Inhalation Studies). Technical Report Series N o. 267. NIH25

Publication No. 85

- 2527. Research Triangle Park, NC: National Toxicology Program. 172

pp.

S. Navarro, A.A. Iskikber, S. Finkelman, M. Rindner, A. Azrieli, R. Dias. 2004. Effectiveness of short exposures of propylene oxide alone and in Combinat ion with low pressure or carbon dioxide against Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). Journal of Stored Products Research, 40:197

- 205.

Storck, W.J. 1981. Output of big

- volume chemicals fell in 1980. Chem. Eng. News, 59 : 36

- 39.

USE PA. 1981. Human exposure to atmospheric concentrations of selected chemicals

. Research Triangle Park, North Carolina, US Environmental Protection Agency, Office of Air Quality Planning and Standards (US NTIS PB 84

- 102540, PB 83

- 265249).

USEPA. 2006. R eregistration Eligibility Decision for Propylene Oxide, EPA 738

- R

- 06

- 029. 192pp. ( http://www.epa.gov/oppsrrd1/reregistration/REDs/propylene_oxide_red.pdf ), (accessed 3/1 8/2013)

USEPA. 2012. BEAD Chemical Profile for Registration Review: Propylene oxide (042501). 5pp.

WHO. 1978. Environmental health problems associated with the manufacture and uses of synthetic organic chemicals, Geneva, World Health Organization (R eport No. HCS/78.2).

WHO. 1985. EHC 55: Ethylene oxide, Geneva, World Health Organization, 79 pp.

Submitted Studies

MRID Citation Reference

47921701 Martin, MA. 2009. Propylene Oxide

– Vegetative Vigor Test with Soybean Following

U.S. EPA OPPTS Draft Guideline 850.1450 (Tier I Test). Springborn Smithers Laboratories, Wareham, Massachusetts. Study no. 13928.6102. Study sponsored by Ag

Chem Consulting LLC (on behalf of ABERCO), Clifton, Virginia. Study completed on November 11, 2009.

47921702 So ftcheck, K.A. 2009. Propylene Oxide

– 7

- Day Static Toxicity Test in a Modified

Closed System with Duckweed (Lemna gibba ). Springborn Smithers Laboratories, Wareham, Massachusetts. Study No. 13928.6101. Study sponsored by Ag

- Chem Consulting LLC (on behalf o f ABERCO), Clifton, Virginia. Study completed on November 11, 2009.

47921703 Softcheck, K.A. 2009. Propylene Oxide

– Static Acute Toxicity Test in a Modified Closed

System with the Freshwater Alga, Pseudokirchneriella subcapitata. Springborn Smithers

Labor atories, Wareham, Massachusetts. Study No. 13928.6100. Study sponsored by Ag

Chem Consulting LLC (on behalf of ABERCO), Clifton, Virginia. Study completed on November 11, 2009.26 

### Appendix I

Modeling Input based on PPO Release Scenarios Specified on Labels

PPO is used to treat food and post

- harvested commodities in fumigation chambers. Labels specify maximum application rates, or indoor concentrations of PPO, which are maintained over periods of time for treatments inside the chambers. Fumigation chambers have a maximum size of 10,000 cubic feet 6 . Labels all require mechanical, or forced, aeration following a treatment of the commodities. Mechanical aeration releases the fumigant outdoors from the treated structure through a through a stack or vent. In t he first set of release scenarios, PPO labels explicitly specify the following mechanical release parameters given the following maximum application

rates and maximum structure sizes:

First Release Scenario

Maximum Application Rate (per chamber) = 75 lbs ./1,000 ft. 3

Maximum Chamber Size = 5,000 ft. 3

Stack Height = 27 ft. Flow Rate = 20 air exchanges per hour = 1,667 cfm for 5,000 ft. 3 chamber

Second Release Scenario

Maximum Application Rate (per chamber) = 75 lbs./1,000 ft. 3

Maximum Chamber Size = 5,000 ft. 3

Stack Height = 40 ft. Flow Rate = 4 air exchanges per hour = 333.33 cfm for 5,000 ft. 3 chamber

Third Release Scenario

Maximum Application Rate (per chamber) = 75 lbs./1,000 ft. 3

Maximum Chamber Size = 10,000 ft. 3

Stack Height = 40 ft.

Flow Rate = 4 air exchanges per hour = 666.67 cfm for 10,000 ft. 3 chamber

The label also allows other release scenarios where mechanical release parameters are not specified. However, for these scenarios, 95 percent of PPO emissions are required to be captured. The se release scenarios which are also defined by maximum application rates and building sizes are described below:

Fourth Release Scenario

Maximum Application Rate (per chamber) = 150 lbs./1,000 ft. 3

6 Fumigation chambers are assumed to possess similar size to railcars. Citation: http://www.csx.com/index.cfm/customers/equipment/railroad

- equipment/27

Maximum Chamber Size = 10,000 ft. 3

Fifth Release Scena rio

Maximum Application Rate (per chamber) = 75 lbs./1,000 ft. 3

Maximum Chamber Size = 5,000 ft. 3

Sixth Release Scenario

Maximum Application Rate (per chamber) = 75 lbs./1,000 ft. 3

Maximum Chamber Size = 10,000 ft. 3

It is important to note that it is p ossible that more than one simultaneous PPO treatments inside fumigation chambers can occur at a time at the same location. The labels do not specify a maximum amount of simultaneous fumigation chamber treatments.

AERSCREEN Description

The Agency’s reco mmended screening dispersion model for the near field, the American Meteorological Society/EPA Regulatory Screening Model (AERSCREEN), will be used to generate screening EECs for the various release scenarios. The Tier I analysis will consider the

emissio n rates and release flow rates and stack parameters for the various mechanical release

scenarios for PPO. Worst

- case meteorological conditions (light winds and stagnant conditions)

and downwash 7 parameters are assumed to calculate peak air EECs, represent ing one

- hour average concentrations. Documentation on the AERSCREEN model is available at http://www.epa.gov/scram001/dispersion_screening.htm . A schematic of release scenarios from fumig ated structures and the related conceptual model for ground

- level exposure is shown in Figure A 1 . For purposes of this screening analysis, all ecological receptors of concern will assumed to be present directly downwind from the building at ground level.

7 Downwash is defined as the downward flow often observed on the leeward side of buildings induced by wake turbulence. Pollutants released from buildings can often b ecome embedded in downwash flows and wake cavities.28

Figure A 1. Schematic illustrating fumigation releases from treated structures and conceptual model for ground

- level exposure.

AERSCREEN Release Scenarios

The release scenarios on the PPO label, which are described above, can be consolidated to three scenarios to capture the possibilities for upper

- bound air exposure resulting from PPO

treatments. These scenarios are described below:

Scenario 1

Maximum Application Rate (per chamber) = 75 lbs./1,000 ft. 3

Maximum Chamber Size = 10,000 ft. 3

Stack Heig ht = 40 ft. Flow Rate = 4 air exchanges per hour = 666.67 cfm for 10,000 ft. 3 chamber

Scenario 2

Maximum Application Rate (per chamber) = 75 lbs./1,000 ft. 3

Maximum Chamber Size = 10,000 ft. 3

Stack Height = 27 ft. Flow Rate = 20 air exchanges per hour = 3,333 cfm for 10,000 ft. 3 chamber

Scenario 3

Maximum Application Rate (per chamber) = 150 lbs./1,000 ft. 3

Maximum Chamber Size = 10,000 ft. 3

95 Percent Emissions Capture Stack Height = 3.33 ft. (Not specified on label, see Table I. 1 for explanation of re lease parameter value) Flow Rate = 1 air exchanges per hour = 166.67 cfm (Not specified on label, see Table I. 1 for explanation of release parameter value)29

The input parameter values used in AERSCREEN for the screening analysis of PPO air exposure

is sho wn in Table A 1 below. The AERSCREEN modeling captures the upper

- bound air exposure from release scenarios consolidated above from information on the PPO product label. All of the modeled release scenarios conservatively assume that aeration is complete a fter one hour which results in maximized peak (one

- hour average) concentrations.

Table A 1. AESCREEN input parameter values capturing the upper

- bound combination of

release scenarios identified on the PPO label.

Input Parameter Option/Value Notes

Scena rio 1 Scenario 2 Scenario 3 English or Metric

Units E (English)

Source Type P (Point) Stack releases required for all

uses

Emission Rate (lbs./hr) 375 375 75 Scenarios 1 and 2

All mass from labeled specified application rate inside 10,000 ft. 3

chamb er released in one

- hour

period 1

Scenario 3 5 percent of total mass from labeled specified application rate inside 10,000 ft. 3 chamber released in one hour period corresponding to 95 percent emissions capture 2

Stack or Release Height Above Ground (ft.) 4 0 27 5 Scenarios 1 and 2: Specified on label

Scenario 3: Not specified on label Default for 10,000 ft. 3 building size based on methyl bromide

HED assessment 3

Stack Diameter (in.) 39.6 Default for 10,000 ft. 3 building size based on methyl bromide

HED assessment (1 meter) 3

Stack Temperature (°F) 0 (Equivalent to Ambient Temperature) No stack temperatures specified, conservative assumption is non

buoyant source Option for Flow

Rate or Flow Velocity 3 (Flow Rate ACFM)30

Table A 1. AESCREEN input parameter values capturing the upper

- bound combination of

release scenarios identified on the PPO label.

Input Parameter Option/Value Notes

Scena rio 1 Scenario 2 Scenario 3

Stack Exit Stream

Flow Rate (f 3 /min.) 333 166

. 7 166. 7 Scenario 1: Based on 4 air exchanges per hour specified on the label 4

Scenario 2: Based on 20 air exchanges per hour specified on the label 4

Scenario 3: Not specified on label

- Assume one air exchange per

hour for one

- hour release 4

Urban or Rural? R (Rural) Conservative default

Minimum

Distance to Ambient Air (ft.) 3.3 Conservative default

NO 2 Chemistry 1 (No chemistry/pollutant is not NO 2 ) Tracer gas NO

x emissions not

modeled Include Building

Downwash? Y (Yes) Downwas h is feasible downward transport mechanism for plume

in release scenarios

Use Pre

- Existing

BPIPPRM File? N (No) Downwash parameters to be input manually Building Height (ft.) 40 27 5 Equivalent to stack height

Maximum

Horizontal Building Dimension (ft.) 11.16 13.6 44.72 Square chamber footprint consistent with building heights specified above

Minimum

Horizontal Building Dimension (ft.) 11.16 13.6 44.72 Square chamber footprint consistent with building heights specified above

Maximum Building

Dimension Angle

to True North (degrees) 0 Conservative parameterization of building downwash

– stack located on the leeward edge of the building Direction of Stack from Building Center (degrees) 0

Distance Between 5.6 6.8 22.331

Table A 1. AESCREEN input parameter values capturing the upper

- bound combination of

release scenarios identified on the PPO label.

Input Parameter Option/Value Notes

Scena rio 1 Scenario 2 Scenario 3 Stack and Building Center (ft.)

T errain Heights? N (No) Only flat terrain considered

Maximum

Distance to Probe (m) 5,000 Default

- maximum feasible

distance for screen

Include Discrete Receptors N (No) Automated receptors sufficient

Flagpole Receptors N (No) Ground

- level concentrations

assumed

Source Elevation (ft.) 0 Stack base from ground release

assumed

Minimum Temperature (°F) - 10 Default

– typical national

temperature range

Maximum Temperature (°F) 100 Default

– typical national

temperature range

Minimum Wind Speed (m/s) 0.5 M inimum in model:

conservative default

Anemometer Height (ft.) 33 Typical boundary layer reference height (10 meters)

Surface

Characteristics Option 1 (Single User Specified Values)

Albedo 0.6 Bare surface assumed around

source 5

Bowen Ratio 3.0 Bar e surface assumed around

source 5

Surface Roughness Length (m) 0.001 Bare surface assumed around

source 5

1 Scenario 1 and 2 Emission Rate (lbs./hr) = Application Rate (lbs./ft. 3 ) x Structure Size (ft. 3 ) Duration of Release (hr.)

2 Scenario 3 Emiss ion Rate (lbs./hr) = 0.05 x Application Rate (lbs./ft. 3 ) x Structure Size (ft. 3 ) Duration of Release (hr.)

3 Methyl bromide HED risk assessment citation: Dawson, J. 2008. Second Addenda to the 2006 (DP Barcode 304623) Phase 5 Human Health Risk As sessment for Commodity Uses. Office of Pesticide Programs. Washington, DC. (November 26, 2008) (EPA DP Barcode 304612).

4 Flow rate (ft. 3 /min) = Air exchange rate (air exchanges/hr.) x Structure Size (ft. 3 ) x hours

60 minutes

5 Default valu es for bare soil assumed. Please refer to, “User’s Guide for the AERMOD Meteorological Preprocessor (AERMET)”, (EPA, 2004) for further details.32 

### Appendix I I

Output Example of AERSCREEN Estimated Environmental Concentration s (EEC s ) for

PPO Release Scenar io 3

AERSCREEN 11126 / AERMOD 1234 04/15/13

14:34:33

TITLE: PPO

- 5

------------------ ----------------------------------------------------------- ***************************** STACK PARAMETERS ****************************

-----------------------------------------------------------------------------

SOURCE EMISSION RATE: 9.4 500 g/s 75.000 lb/hr

STACK HEIGHT: 1.52 meters 5.00 feet

STACK INNER DIAMETER: 1.006 meters 39.60 inches

PLUME EXIT TEMPERATURE: Ambient

PLUME EXIT VELOCITY: 0.099 m/s 0.32 ft/s

STACK AIR FLOW RATE: 167 ACFM

RURAL OR URBAN: RURAL

INITIAL PROBE DISTANCE = 5000. meters 16404. feet

--------------------------------------------------- -------------------------- *********************** BUILDING DOWNWASH PARAMETERS **********************

-----------------------------------------------------------------------------

BUILDING HEIGHT: 1.5 meters 5.0 fee t
MAX BUILDING DIMENSION: 13.6 meters 44.7 feet

MIN BUILDING DIMENSION: 13.6 meters 44.7 feet BUILDING ORIENTATION TO NORTH: 0. degrees STACK DIRECTION FROM CENTER: 0. degrees

STACK DISTA NCE FROM CENTER: 6.8 meters 22.3 feet

----------------------------------------------------------------------------- ************************** FLOW SECTOR ANALYSIS ***************************

25 meter recepto r spacing: 1. meters

- 5000. meters

-----------------------------------------------------------------------------

FLOW BUILD BUILD MAX 1

- HR DIST TEMPORAL

SECTOR WIDTH LENGTH XBADJ YBADJ CO NC (m) PERIOD

----------------------------------------------------------------------------- 10 15.80 15.79

- 14.59

- 1.18 0.2280E+07 1.0 ANN

20 17.48 17.47

- 15.12

- 2.32 0.2900E+07 1.0 ANN

30 18.63 18.62

- 15.20

- 3.40 0.3326E+07 1.0 ANN

40 19.21 19.21

- 14.81

- 4.37 0.2848E+07 1.0 ANN33 50 19.21 19.21

- 13.97

- 5.21 0.2162E+07 1.0 ANN

60 18.62 18.63

- 12.71

- 5.88 0.1706E+07 1.0 ANN

70 17.47 17.48

- 11.06

- 6.39 0.1326E+07 1.0 ANN

80 15.79 15.80

- 9.08

- 6.69 0.1016E+07 1.0 ANN

90 13.63 13 .64

- 6.82

- 6.80 0.8461E+06 25.0 ANN

100 15.79 15.80

- 6.72

- 6.69 0.7199E+06 25.0 ANN

110 17.47 17.48

- 6.42

- 6.39 0.6613E+06 25.0 ANN

120 18.62 18.63

- 5.92

- 5. 88 0.6334E+06 25.0 ANN

130 19.21 19.21

- 5.24

- 5.21 0.5796E+06 25.0 ANN

140 19.21 19.21

- 4.40

- 4.37 0.6181E+06 25.0 ANN

150 18.63 18.62

- 3.43

- 3.40 0.6176E+06 2 5.0 ANN

160 17.48 17.47

- 2.35

- 2.32 0.6368E+06 25.0 ANN

170 15.80 15.79

- 1.20

- 1.18 0.7031E+06 25.0 ANN

180 13.64 13.63

- 0.02 0.00 0.6304E+06 25.0 ANN

190 15.80 15.79

- 1.20 1.18 0.7031E+06 25.0 ANN

200 17.48 17.47

- 2.35 2.32 0.6368E+06 25.0 ANN

210 18.63 18.62

- 3.43 3.40 0.6176E+06 25.0 ANN

220 19.21 19.21

- 4.40 4.37 0.6181E+06 25.0 ANN

230 19.21 19.21

- 5.24 5.21 0.5796E+06 25.0 ANN

240 18.62 18.63

- 5.92 5.88 0.6334E+06 25.0 ANN

250 17.47 17.48

- 6.42 6.39 0.6613E+06 25.0 ANN

260 15.79 15.80

- 6.72 6.69 0.7199E+06 25.0 ANN

270 13.63 13.64

- 6.82 6.80 0.8461E+06 25.0 ANN

280 15.79 15.80

- 9.08 6.69 0.1016E+07 1.0 ANN

290 17.47 17.48

- 11.06 6.39 0.1326E+07 1.0 ANN

300 18.62 18.63

- 12.71 5.88 0.1706E+07 1.0 ANN

310 19.21 19.21

- 13.97 5.21 0.2162E+07 1.0 ANN

320 19.21 19.21

- 14.81 4.37 0.2848E+07 1.0 ANN

330 18.63 18.62

- 15.20 3.40 0.3326E+07 1.0 ANN

340 17.48 17.47

- 15.12 2.32 0.2900E+07 1.0 ANN

350 15.80 15.79

- 14.59 1.18 0.2280E+07 1.0 ANN

360* 13.64 13.63

- 13.61 0.00 0.1677E+08 1.0 ANN

* = worst case flow sector

-----------------------------------------------------------------------------

*********** *********** MAKEMET METEOROLOGY PARAMETERS *********************

-----------------------------------------------------------------------------

MIN/MAX TEMPERATURE: 249.8 / 310.9 (K)

MINIMUM WIND SPEED: 0.5 m/s

ANEMOMETER HEIGHT: 33.00 0 meters

SURFACE CHARACTERISTICS INPUT: USER ENTERED

ALBEDO: 0.60

BOWEN RATIO: 3.00 ROUGHNESS LENGTH: 0.001 (meters)

METEOROLOGY CONDITIONS USED TO PREDICT OVERALL MAXIMUM IMPACT

------------------ -------------------------------------------34

YR MO DY JDY HR

-- -- -- --- -- 10 01 07 7 01

H0 U* W* DT/DZ ZICNV ZIMCH M

- O LEN Z0 BOWEN ALBEDO REF WS

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

- 0.02 0.010

- 9.000 0.020

- 999. 2. 3.3 0.001 3.00 0.60 0.50

HT REF TA HT

- - - - - - - - - - - 33.0 249.8 2.0

ESTIMATED FINAL PLUME HEIGHT (non

- downwash): 1.2 meters

METEOROLOGY CONDITIONS USED TO PRED ICT AMBIENT BOUNDARY IMPACT

--------------------------------------------------------------

YR MO DY JDY HR

-- -- -- --- -- 10 01 07 7 01

H0 U* W* DT/DZ ZICNV ZIMCH M

- O LEN Z0 BOWEN ALBEDO REF WS

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

- 0.02 0.010

- 9.000 0.020

- 999. 2. 3.3 0.001 3.00 0.60 0.50

HT REF TA HT

- - - - - - - - - - - 33.0 249.8 2.0

ESTIMATED FINAL PLUME HEIGHT (non

- downwash): 1 .2 meters

----------------------------------------------------------------------------- ************************ AERSCREEN AUTOMATED DISTANCES **********************

OVERALL MAXIMUM CONCENTRATIONS BY DISTANCE

---------------------- -------------------------------------------------------

MAXIMUM MAXIMUM

DIST 1

- HR CONC DIST 1

- HR CONC (m) (ug/m3) (m) (ug/ m3)

--------------------- --------------------- 1.01 0.1677E+08 2525.00 0.1788E+05

25.00 0.1814E+07 2550.00 0.1762E+05

50.00 0.9855E+06 25 75.00 0.1738E+05

75.00 0.7962E+06 2600.00 0.1714E+05

100.00 0.6616E+06 2625.00 0.1690E+05

125.00 0.6227E+06 2650.00 0.1667E+05

150.00 0.6382E+06 2675.00 0.1645E+05

175.00 0.6128E+06 2700.00 0.1623E+05

200.00 0.5628E+06 2725.00 0.1601E+05

225.00 0.5038E+06 2750.00 0.1580E+05

250.0 0 0.4464E+06 2775.00 0.1560E+05

275.00 0.3953E+06 2800.00 0.1540E+0535 300.00 0.3519E+06 2825.00 0.1520E+05

325.00 0.3155E+06 2850.00 0.1501E+05

350.00 0.2849E+06 2875.00 0.1482E+05

375.00 0.2590E+06 2900.00 0.1463E+05

400.00 0.2369E+06 2925.00 0.1445E+05

425.00 0.2178E+06 2950.0 0 0.1428E+05

450.00 0.2013E+06 2975.00 0.1410E+05

475.00 0.1868E+06 3000.00 0.1393E+05

500.00 0.1739E+06 3025.00 0.1376E+05

525.00 0.1626E+06 3050.00 0.1360E+05

550.00 0.1524E+06 3075.00 0.1344E+05

575.00 0.1433E+06 3100.00 0.1328E+05

600.00 0.1351E+06 3125.00 0.1313E+05

625.00 0.1277E+06 3150.00 0.1298E+05

650.00 0.1209E+06 3175.00 0.1283E+05

675.00 0.1147E+06 3200.00 0.1268E+05

700.00 0.1091E+06 3225.00 0.1254E+05

725.00 0.1039E+06 3250.00 0.1240E+05

750.00 0.9908E+05 3275.00 0.1226E+05

775.00 0.9466E+05 3300.00 0.1212E+05

800.00 0.9057E+05 3325.00 0.1199E+05

825.00 0.8677E+05 3350.00 0.1186E+05

850.00 0.8323E+05 3375.00 0.1173E+05

875.00 0.7994E+05 3400.00 0.1161E+05

900.00 0.7686E+05 3425.00 0.1148E+05

925.00 0.7397E+05 3450.00 0.1136E+05

950.00 0.7127E+05 3475.00 0.1124E+05

975.00 0.6873E+05 3500.00 0.1112E+05

1000.00 0.6 634E+05 3525.00 0.1101E+05

1025.00 0.6409E+05 3550.00 0.1089E+05

1050.00 0.6196E+05 3575.00 0.1078E+05

1075.00 0.5995E+05 3600.00 0.1067E+05

1100.00 0.5806E+05 3625.00 0.1056E+05

1125.00 0.5626E+05 3650.00 0.1046E+05

1150.00 0.5455E+05 3675.00 0.1035E+05

1175.00 0.5293E+05 3700.00 0.1 025E+05

1200.00 0.5139E+05 3725.00 0.1015E+05

1225.00 0.4992E+05 3750.00 0.1005E+05

1250.00 0.4853E+05 3775.00 9952.

1275.00 0.4719E+05 3800.00 9855.

1300.00 0.4592E+05 3825.00 9760.

1325.00 0.4471E+05 3850.00 9667.

1350.00 0.4355E+05 3875.00 9575.

1375.00 0.4244E +05 3900.00 9484.

1400.00 0.4137E+05 3925.00 9395.

1425.00 0.4035E+05 3950.00 9307.

1450.00 0.3938E+05 3975.00 9221.

14 75.00 0.3844E+05 4000.00 9135.

1500.00 0.3754E+05 4025.00 9051.

1525.00 0.3667E+05 4050.00 8969.

1550.00 0.3584E+05 4075.00 8887.

1575.00 0.3504E+05 4100.00 8807.

1600.00 0.3427E+05 4125.00 8728.

1625.00 0.3352E+05 4150.00 8650.

1650.00 0.3281E+05 41 75.00 8573.

1675.00 0.3211E+05 4200.00 8497.36

1700.00 0.3145E+05 4225.00 8423.

1725.00 0.3080E+05 4250.00 8349.

1750.00 0.3018E+05 4275.00 8276.

1775.00 0.2958E+05 4300.00 8205.

1800.00 0.2900E+05 4325.00 8134.

1825.00 0.2844E+05 4350.00 8065.

1850.0 0 0.2789E+05 4375.00 7996.

1875.00 0.2736E+05 4400.00 7928.

1900.00 0.2685E+05 4425.00 7861.

1925.00 0.2636E+05 4450.00 7796.

1950.00 0.2588E+05 4475.00 7731.

1975.00 0.2541E+05 4500.00 7666.

2000.00 0.2496E+05 4525.00 7603.

2025.00 0.2452E+05 4550.0 0 7541.

2050.00 0.2410E+05 4575.00 7479.

2075.00 0.2368E+05 4600.00 7418.

2100.00 0.2328E+05 4625.00 7358.

2125.00 0.2289E+05 4650.00 7299.

2150.00 0.2251E+05 4675.00 7241.

2175.00 0.2214E+05 4700.00 7183.

2200.00 0.2179E+05 4725.00 7126.

2225.00 0.2144E+05 4750.00 7070.

2250.00 0.2110E+05 4775.00 7014.

2275.00 0.2076E+05 4800.00 6959.

2300.00 0.2044E+05 4825.00 6905.

2325.00 0.2013E+05 4850.00 6852.

2350.00 0.1982E+05 4875.00 6799.

2375.00 0.1952E+05 4900.00 6747.

2400.00 0.1923E+05 4925.00 6695.

2425.00 0.1895E+05 4950.00 6644.

2450.00 0.1867E+05 4975.00 6594.

2475.00 0.1840E+05 5000.00 6544.

2500.00 0.1813E+05

---- ------------------------------------------------------------------------- ********************** AERSCREEN MAXIMUM IMPACT SUMMARY *********************

-----------------------------------------------------------------------------

MAXIMUM SCALED SCALED SCALED SCALED

1

- HOUR 3

- HOUR 8

- HOUR 24

- HOUR ANNUAL

CALCULATION CONC CONC CONC CONC CONC PROCEDURE (ug/m3) (ug/m3) (ug/m3) (ug/m3) (ug/m3)

--------------- ---------- ---------- ---------- ---------- ---------- FLAT TERRAIN 0.1677E+08 0.1677E+08 0.1509E+08 0.1006E+08 0.1677E+07

DISTANCE FROM SOURCE 1.01 meters directed toward 360 degrees

IMPACT AT THE

AMBIENT BOUNDARY 0.1677E+08 0.1677E+08 0.1509E+08 0.1006E+08 0.1677E+07

DISTANCE FROM SOURCE 1.01 meters directed toward 360 degrees