UNITED STA TES ENVIRONMENTA L PROTECTION AGENCY WASHINGTON D.C., 20460

PC Code: 077702 DP Barcode: 344574 MEMORANDUM Subject: Registration Review

– Preliminary problem formulation for the Ecological Risk

Assessment of Propionic Acid To: Wilhelmena Livingston

Reregistration Branch 7508P Special Review and Reregistration Division From: William Shaughnessy , Ph.D., Environmental Scientist

Carolyn Hammer, Environmental Scientist Through: Dana Spatz, Acting Chief

Environmental Risk Branch 2 Environmental Fate and Effects Division Office of Pesticide Programs Attached is the preliminary problem formulation for the ecological risk assessment to be conducted as part of the Registration R eview of the fungicide and bactericide propionic acid.

## Registration Review Ecological Risk Assessment Problem Formulation F or 

# Propionic Acid and Salts Synonyms: Methylacetic acid; ethylformic acid; propanoic a cid;

carboxyethane PC Code: 077702 

## Chemical Formula: CH 3 

## CH 2 

## COOH

Prepared By: Carolyn Hammer, Environmental Scientist Wm. J. Shaughnessy, Ph.D., Environmental Scientist Environmental Risk Branch 2 Environmental Fate and Effects Division Office of Pesticide Programs 

## Approved By: Dana Spatz, Chief Environmental Risk Branch 2 Environmental Fate and Effects Division Office of Pesticide Programs1



### Stressor Source and Distribution Propionic acid is a fungicide and bactericide that is registered to control fungi and bacteria i n stored hay and grains. It is formulated as a liquid and sprayed onto hay and grain at the time of baling. Currently , two manufacturing

- use pesticide products are registered, as are 12 end

- use products, each containing p ropionic acid as its sole active ingredient. The pesticide is a colorless, oily, pungent liquid that is soluble in water and occurs naturally in animals and dairy products. It also is a normal component of metabolism in the human body

. Humans consume naturall y- occurring p ropionic acid i n common foods such as butter and cheese ( Swiss cheese may contain as much as one percent p ropionic acid), and as an added ingredient in other foods. In its more concentrated form i t is corrosive and flammable, thus requiring special handling. The activ e ingredient p ropionic acid is a fungicide/bactericide used to : (1) preserve stored grains for animal and human consumption, (2) inhibit bacterial growth in drinking water for livestock and poultry , (3) control mold and fungi in poultry litter and animal f eed, and (4) sanitize pre

- cleaned food contact surfaces. Propionic acid is formulated as soluble concentrate (10%, 70.5

- 70.6% a

. i

. ), solution (70.5% a

. i

. ), and granular (15% a . i

. ). Application rates to grains are dependent on the moisture content of the grain at the time it is placed in storage , up to 31 pounds per ton . Propionic acid is also used as an inert ingredient in pesticide formulations. EFED was not provided with the name(s) of chemicals that are formulated with this inert ingredient. Propio nic acid and its salts, sodium and calcium propionates, are approved in the United States as Generally Recognized As Safe (GRAS) (21 CFR 184.1081) for use in food. Their antimicrobial action is directed to molds and rope bacteria, with almost no effect on yeast, thus making them an ideal choice for products that use commercial yeast as an ingredient. Propionic acid is applied undiluted to grain and hay with a calibrated liquid metering applicator that provide s the desired coverage to grain as it is moved into storage, or to hay just prior to bailing and stacking. In general, the rate of application is a function of the moisture content of the grain or hay and occurs within the bailing equipment. It has also been approved for outdoor use as an additive to poultry and live stock drinking water. 1 The application rate of active ingredient ranges significantly per ton of hay and grain, depending on the moisture content (see Table 1)

. The following parameters are not specified on the label and therefore not included in the table below: the maximum number of applications per crop cycle or year, maximum application rate, and mini mum application interval (day s).

1 USEPA 1991. Reregistration Eligibility Document

– Propionic Acid, and Salts. Office of Pesticide Programs, Special Review and Reregistration Division. September 1991.2

Table 1. Li sting of the label uses, application rates, form and equipment for p ropionic acid as an active ingredient. Use Site Max. Rate per App Max. Rate

Unit/Area *UG Form Application Equipment //Type (Reg # Code) NON - FOOD/NON - FEED USES silos .2981 lb 1K sq.ft *M1 SC/L Not on label //I nd oor general surface treatment (a) FOOD/FEED USES alfalfa 15 lb ton (L) *B1 RTU Sprayer //Spray/ Stored commodity non

- fumigation (a) animal drinking water 8824 W ppm *L 1 SC/L Not on label //Water treatment (a) barley 1.528 lb cwt *L 1 RTU Sprayer //Spray (a) barley 31 lb ton (L) *B1 RTU Sprayer //Stored commodity non

- fumigation (b) cereal grains 29 lb ton (L) *A2 RTU Low pressure //Grain treatment (a) corn (silage) 3 lb ton (L) *B1 RTU

SC/L Low pressure/ Low pressure ground sprayer/

Sprayer //Spray (a) corn (unspecified) .8458 lb cwt *A2 RTU Sprayer //Spray (a) corn (unspecified) 6 lb A (L) *A2 SC/L Low pressure //Spray (b) corn (unspecified) 23 lb ton (L) *B1 RTU Sprayer //Stored commodity non

- fumigation (c) corn, fi eld 1.156 lb cwt *A2 RTU Sprayer //Spray (a) cowpeas 31 lb ton (L) *B1 RTU Low pressure ground sprayer //Stored commodity non

- fumigation (a) dairies/cheese processing plant equipment (food contact) 158 W ppm *L 1 SC/L Not on label //Circulation treatment (a) feed/food commodities (bagged/temporary storage) 4 lb ton (L) *L 1 RTU

SC/L Sprayer

//Spray (a) food processing plant equipment (food co ntact) 158 W ppm *L 1 SC/L Not on label //Circulation treatment (a) grain/cereal/flour (bagged/temporary storage) 1 lb ton (L) *L 1 RTU Low pressure //Spray (a) grain/cereal/flour storage areas

empty .2981 lb 1K sq.ft *L 1 SC/L Not on label //I ndoor general surface treatment (a)
grass forage/fodder/hay 20 lb ton (L) *B1 RTU

SC/L Low pressure/ Low pressure ground sprayer/

Metering pump3 Use Site Max. Rate per App Max. Rate

Unit/Area *UG Form Application Equipment //Type (Reg # Code) //Spray (a) hay (silage) 4 lb ton (L) *B1 RTU

SC/L Low pressure/ Sprayer

//Spray (a) livestock feed (processed) 1.428 lb ton *L 1 SC/L Not on label //Stored commodity non

- fumigation (a) nongrass forage/fodder/straw/hay 31 lb ton (L) *B1 RTU Low pressure //Grain treatment (a) oats 1.528 lb cwt *L 1 RTU Sprayer //Spray (a) oats 31 lb ton (L) *B1 RTU Sprayer //Stored commod ity non

- fumigation (b) peanuts 31 lb ton (L) *B1 RTU Low pressure ground sprayer //Stored commodity non

- fumigation (a) peas (including vines) 31 lb ton (L)*B1 RTU Low pressure ground sprayer //Stored commodity non

- fumigati on (a) poultry drinking water 8824 W ppm *L 1 SC/L Not on label //Water treatment (a) poultry feed (processed) 1.428 lb ton *L 1 SC/L Not on label //Stored commodity non - fumigation (a) poultry l itter .2981 lb 1K sq.ft *L 1 SC/L Not on label //Animal bedding/litter treatment (a) small grains 4 lb ton (L) *B1 RTU

SC/L Low pressure/ Sprayer

//Spray (a) sorghum 1.528 lb cwt *L 1 RTU Sprayer //Spray (a) sorghum 31 lb ton (L) *B1 RTU Sprayer //Stored commodity non

- fumigation (b) sorghum (unspecified) .8458 lb cwt *A2 RTU Sprayer //Spray (a) soybeans 31 lb ton (L) *B1 RTU Low pressure ground sprayer //Stored commodity non

- fumigation (a) wheat 1.528 lb cwt *L 1 RTU Sprayer //Spray (a) wheat 31 lb ton (L) *B1 RTU Sprayer //Stored commodity non

- fumigation (b)

LEGEND HEADER ABBREVIATIONS Use Site : The use site refers to the entity (crop, building, surface or article) w here a pesticide is applied and/or which is being prote cted. Max.Rate per App : Maximum dose for a single application to a single site. System calculated. Max.Rate Unit/Area : Units and Area associated with the maximum dose. *UG : Use Group codes.4

Form : T he physical form of the end use product found in the container. Max. # Apps cc & yr : The maximum number of applications. Max. App Rate/cc & yr : The maximum amount of pesticide product that can be applied to a site in one

growing season (/cc) or during the span of one year (/yr). Min. App Interval (days): The minimum retreatment interval between applications in days (aggregated). Application Equipment : The equipment used to apply pesticide (aggregated). Application Ty

pe : The type of pesticide application (aggregated). Current as of

- : The label data for the listed products in this report is current as of this date. ABBREVIATIONS AN

- As Needed. NA

- Not Applicable. NS

- Not Specified (on labe l). (L)

- The dosage information provided is from the label in terms of product (e.g., ounces, gallons, or pounds of the product) because there was insufficient information (e.g., missing density, area, or active ingredient percentages) to p rovide converted dosage information.
~ - The tilde in "Max. Rate per App" indicates a dosage that includes information from a SLN label. UC

- Unconverted due to lack of data (on label). APPLICATION RATE W : PPM calculated by w eight V : PPM calculated by volume U : Unknown whether PPM is given by weight or by volume cw t : Hundred Weight. nnE

- xx : nn times (10 power - xx), for instance, "1.234E

- 4" is equivalent to ".0001234".

-- : No description available in LUIS unit conversion vocabulary. ~ : The dosage information includes a contribution from one or more (TQ, CL, BR, I)

active ingredients. FORMULATION CODES RTU : Liquid

- ready To Use SC/L : Soluble Concentrate/liquid USE GROUP CODES A2 : TERRESTRIAL FOOD+FEED CROP B1 : TERRESTRIAL FEED CROP L1 : INDOOR FOOD M1 : INDOOR NON

- FOOD


### I ntegra tion of A

vailable Information Propionic acid was first registered as a pesticide in the earl y 1970's. In 1975, EPA first exempted p ropionic acid from tolerances for residues following post

- harvest application in grains or hay s (40 CFR 180.1023). In Sept ember 1991, EPA completed a Reregistration Eligibility Document (RED) for p ropionic acid and salts. In this document the EPA noted that data available at that time was sufficient to support the conclusion that the registered uses of p ropionic acid would n ot result in unreasonable adverse effects to human health and the environment . The RED also noted that p ropionic acid is exempt from the requirement of a tolerance when applied (as an inert ingredient) to growing crops or to raw agricultural commodities a fter harvest as describe d in 40 CF R 180.1001c. The current assessment considers the risks from p ropionic acid as an active ingredient applied post

- harvest. When the RED was published in 1991, EPA waived all5

environmental fate and ecological effects data requirements because the use profile did not lead the Agency to foresee the potential for significant environmental risks associated with the registered uses of p ropionic acid

. 

### Ecological Effects P ropionic acid has limit ed outdoor use and low toxicity, therefore its hazard to non

target organisms is expected to be minimal. Previous assessments have determined that all ecological effects data requirements were waived but this conclusion will be reconsidered in the current reregistration assessment. The existing toxicity dataset includes acute studies on freshwater fish and invertebrates, birds, and mammals. Propionic acid is classified as slightl y t oxic to aquatic organisms on an acute basis. Toxicity data are not available to assess the effects of chronic exposure to freshwater organisms or acute and chronic effects to estuarine/marine organisms. Propionic acid is classified as practically non - toxic to birds and mammals on an acute basis. There are no available data on reproductive effects to birds and mammals. Aquatic Effects An acute toxicity study with freshwater fish , Rainbow trout, resulted in a 96

- hr LC 50 = 51 ppm 2

. For the freshwater invertebrate Daphnia magna , acute toxicity testing resulted in a 48

- hour EC 50 =22.7 ppm (MRID # 00068178)

. Each study was a static test where p ropionic acid was assumed to be 100% a.i. It was not measured for verification. Terrestrial Effects Mammalian acute toxicity tests resulted in a rat LD 50 =2,600 mg/kg (Accession no.091042) . Although death was not an obvious endpoint resulting from exposure to p ropionic acid, ocular and dermal irritation was reported ( MRID # 41456306, 46125010 ). An avian acute oral toxicity test with mallard duck resulted in an LD 50 1467 mg/kg (MRID #: 00079594) . Sub

- acute, 8

- day dietary exposure of mallard duck and bobwhite quail to the salts of p ropionic acid resulted in LC50 values greater than 10,000 (MRID #: 00085932, 00079595) . These studies need to be reevaluated to verify the rates/units of exposure as well as the exposure media . The use of p ropionic salts data may not be relevant and therefore would not qualify as a measurement endpoint with which to assess effects to birds, amphibians, and reptiles. D ermal effects tests were not conducted with birds . However, based on mammalian testing described above and label warnings of danger to wildlife, it can be assumed that exposure to p ropionic acid will have a severely irritating and corrosive effect on birds, amphibians and reptiles. The impacts of such an

2 Acute Toxicity to Freshwater Fish. Animal Biol. Lab., EPA

- TSD, Test No. 604, June 1973; Test No. 609, September 1973.6

effect may vary by s pecies. Amphibians, which respire through their skin, may experience severe effects from this ty pe of exposure. Although plant toxicity data are not available, the product label warns “Treatment inhibits germination; do not use on grain intended for se ed or malting, or for use in human foods.” This indicates a potential for effects to non

- target plants if they are exposed to p ropionic acid. Therefore, it can be assumed that if non

- target plants are exposed, seed germination will be inhibited and plant s may exhibit reproductive effects. 

### Exposure Characteristics Environmental Fate/Exposure: Propionic acid's production and use as a grain preservative and as an additive in livestock drinking water, may result in its release to the environment through v arious waste streams. Propionic acid is formed from various enzy matic and fermentation processes and is produced during anaerobic carbohydrate fermentation in the stomachs of ruminants. It occurs in dairy products in small amounts and its esters are foun d in some essential oils. TERRESTRIAL FATE: With an estimated Koc value of 36 derived from a log Kow of 0.33 p ropionic acid is expected to have very high mobility in soil , therefore, leaching into groundwater may occur. The pKa of p ropionic acid is 4.87, indicating that this compound will exist primarily in the anion form in the environment and anions generall y do not adsorb more strongl y t o soils containing organic carbon and clay than their neutral counterparts. 3 Propionic acid in its anionic form would not volatilize from water or moist soil surfaces. The Henry’s Law Constant for Propionic acid is 4.45E

- 7 atm

- cu m/mole. Propionic acid is expected to volatilize from dry soil surfaces based upon a vapor pressure of 3.53 mm Hg. Propionic acid is expect ed to be readily biodegradable under most environmental conditions based on the results of a sewage inoculum screening test that measured theoretical BODs ranging from 23

- 55%. 4 AQUATIC FATE: The estimated Koc value of 36 suggests that p ropionic acid is n ot expected to adsorb to suspended solids and sediment. A pKa of 4.87 indicates p ropionic acid will exist almost entirely in the anion form at pH values of 5 to 9 and therefore volatilization from water surfaces is not expected to be an important fate pro cess. 5 Leaching into groundwater may occur. Hydroly sis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrol yz e under environmental conditions. According to a classification scheme 6 , an estimated BCF of 3.2, from its log Kow and a regression

- derived equation 7 , suggests the potential

3 Doucette WJ; pp. 141

- 188 in Handbook of Property Estimation Methods for Chemicals. Boethling RS, Mackay D, eds. Boca Raton, FL: Lewis Publ (2000) 4 Heukelekian H, Rand MC; J Water Pollut Control Assoc 2 9: 1040

- 53 (1955) 5 Doucette WJ; pp. 141

- 188 in Handbook of Property Estimation Methods for Chemicals. Boethling RS, Mackay D, eds, Boca Raton, FL: Lewis Publ (2000) 6 Franke C et al; Chemosphere 29: 1501

- 14 (1994) 7 Meylan WM et al; Environ Toxicol Chem 1 8: 664

- 72 (1999)7

for bioconcentration in aquatic organisms is low. Propionic acid is expected to be readil y biodegradable in most environmental conditions based on the results o f a sewage screening test that measured theoretical BODs of 23

- 55%. 8 ATMOSPHERI C FATE: According to a model of gas/particle partitioning of semi

volatile organic compounds in the atmosphere 9 , p ropionic acid, which has a estimated vapor pressure of 3.53 mm Hg at 25 deg C, is expected to exist solely as a vapor in the ambient atmosphere. Vapor

- phase p ropionic acid is degraded in the atmosphere b y reaction with photochemically

- produced h ydrox yl radicals; the half

- life for this reaction in air is estimated to be 13 day s, calculated from its rate constant of 1.22X10

- 12 cu cm/molecule

- sec at 25 deg C. 10 Propionic acid is not expected to directly photoly ze due to the lack of absorbance in the environmental UV spectrum. Evaporation from dry surfaces is expected, e speciall y when present in high concentrations such as in spill situations. Table 2 contains a summary of the ph ys ical

- chemical properties of p ropionic acid. Table 2 . Chemical

- Phy sical Properties Property Value Reference CAS 79

- 09

- 4 H azardous Substance D ata Base (HSDB) Formula C 3 H 6 O 2 HSDB Molecular weight 74.08 HSDB Dissociation constant; pKa 4.88 Serjeant EP, Dempsey B; Ionization Constants of Organic Acids in Aqueous Solution. IUPAC Chem Data Ser No. 23. NY, NY: Pergamon Press, Inc. 1979 Koc 36 Swann RL et al; Res Rev 85: 17

- 28. 1983. Lo g Kow 0.33 Hansch C et al; Exploring QSAR. Hydrophobic, electronic, and Steric Constants. ACS Prof Ref Book. Heller SR, Consult. Ed., Wash., DC Solubility (mg/L at 25°C) 1E+6 HSDB Vapor pressure (mm Hg at 25°C) 3.5 3 Lym an WJ; p. 31 in Environmental Exposure

8 Heukelekian H, Rand MC; J Water Pollut Control Assoc 29: 1040

- 53 (1955) 9 Bidleman TF; Environ Sci Technol 22: 361

- 367 (1988) 10 Atkinson R; J Phys Chem Ref Data Monograph No. 1 (1989)8 From Chemicals Vol I, Neel y W B, Blau GE, eds, Boca Raton, FL: CRC Press. 1985 Henry ’s law constant (atm

- cu m/mole) 4.45E

- 7 HSDB



### Characteristics of Ecos ys tems Potentially at Risk For p ropionic acid and pestic ides in general, the ecosy stems at risk are those in close proximity to the use areas. These would include agricultural fields, surrounding terrestrial habitats, and water bodies directly adjacent to treated fields that may receive chemical residues via drift, volatilization, or runoff. Within water bodies, the water column, sediment, and pore water are all compartments of concern. In the case of p ropionic acid, which is applied during or after harvest, exposure to the environment decreases. The element s of the ecos ys tem that may be impacted include birds, amphibians, reptiles and small mammals that utilize the harvested field for all or part of their life

- cycle. Non

- target plants near the edge

- of

- field may be exposed by spray drift or over spray . Th e assessment endpoints are intended to reflect population sustainability and community structure within ecosystems and hence relate back to ecos ys tems at risk. If risks are expected for given species/taxa based on the screening

- level assessment, then risk s might be expected to translate to higher levels of biological organization. Organisms of concern include birds, mammals, reptiles, fish, and terrestrial and aquatic invertebrates, plants, and amphibians. Based on the known effects to plants, as listed on the label, terrestrial plants may be the primary concern. 

### As sessment Endpoints Assessment endpoints are defined as “explicit expressions of the actual environmental value that is to be protected.” Defining an assessment endpoint involves two steps: 1 ) identifying the valued attributes of the environment that are considered to be at risk; and 2) operationall y defining the assessment endpoint in terms of an ecological entity (i.e., a community of fish and aquatic invertebrates) and its attributes (i.e., survival and reproduction). Therefore, selection of the assessment endpoints is based on valued entities (i.e., ecological receptors), the ecos ys tems potentially at risk, the migration pathway s of pesticides, and the routes b y which ecological receptors are exposed to pesticide

- related contamination. The selection of clearl y defined assessment endpoints is important because they provide direction and boundaries in the risk assessment for addressing risk management issues of concern. Changes to assessment endpoints are ty picall y estimated from the available toxicity studies, which are used as the measures of9

effects to characterize potential ecological risks associated with exposure to a pesticide, such as p ropionic acid. To estimate exposure concentrati ons, the ecological risk assessment considers a single application at the maximum application rate to fields that have vulnerable soils. However, in this case, the pesticide is not applied to the field. The most sensitive toxicity endpoints are used fro m surrogate test species to estimate treatment

- related direct effects on acute mortality and chronic reproductive, growth and survival assessment endpoints. Toxicity tests are intended to determine effects of pesticide exposure on birds, mammals, fish, terrestrial and aquatic invertebrates, and plants. These tests include short

term acute, sub

- acute, and reproduction studies and are typicall y arranged in a hierarchical or tiered s ys tem that progresses from basic laboratory tests to applied field studies. The toxicity studies are used to evaluate the potential of a pesticide to cause adverse effects, to determine whether further testing is required, and to determine the need for precautionary label statements to minimize the potential adverse effects to no n target animals and plants. In past assessments of p ropionic acid, many of the effects testing requirements have been waived

. 

### Conceptual Model Th e conceptual model (see Figure TBD ) depicts the potential pathway s for ecological risk associated with p rop ionic acid use. The conceptual model provides an overview of the expected exposure routes for organisms within the p ropionic acid action area. For terrestrial organisms, the major route of exposure considered is spray drift or overspray . Aquatic animal species are unlikely to be exposed to p ropionic acid due to label restrictions

. For terrestrial and wetland plants, the major route is spray drift and overspray .10 Application of Propionic Acid During Baling Operations
Spray Drift Overspra y Runoff/ Erosion Stressor Source: Transport Pathway
Source: Exposure Media

Exposure Point
Receptors

Direct Effects

Indirect Effects Leaching

Terrestrial Food Residues (foliage, fruit, and insects Upland Soil and foliage Riparian/ Wetland Foliage/ Soil Surface Wa ter and Sedime nt Groundwa ter

Direct Conta ct & Ingestion Direct Contact/ Root Uptake Uptake/Ad sorption Gill Integument Uptake

Terrestria l Vertebra tes and Invertebrates Terrestrial Upland Plants Riparian/ Wetland Pl an ts Aquatic Plants Aquatic Vertebra tes and Invertebrates
Terrestri al Animals:
• Lethality
• Reproductive/ developmental Effects
• Suble thal effects (corrosion and ocula r damage) Non - Target Plants:
• Plant Growth Abnormalities
• Lethality
• Developmental/ Reproductive Effects Plant Populati on: • Reduced Population Growth Aquati c Animals and Plants:
• Effects to survival, growth, and reproduction
• Reductions in cell density/biomass in aquatic plants

Altered Terrestrial Community Assemblages: Reduced food supply and edge hab itat ava ilability Altered Aquati c Community Assemblages:
• Effects to ripa ria n habita t availability
• Effects to species abundance/d iversity
• Changes in physical/chemical parameters Figure 1. Conceptual Diagram of Ecological Exposure to Propionic Acid. Risk Hypothesis If p ropionic acid travels off field via spray drift, it is possible that non

- target organisms may be affected, especially plants. Although no phy totoxicity tests have been submitted, the label warns that applying p ropionic acid to seed will inhibit germi nation. Therefore, it can be assumed that if non

- target plants are exposed, seed germination will be inhibited and they may exhibit reproductive effects. In the absence of seedling emergence and vegetative vigor studies and information regarding the like lihood and quantity of spray drift , risk to non

- target plants from p ropionic acid use will be assumed. Propionic acid is classified as slightl y t oxic, to non

- toxic on an acute basis. Most organisms will metabolize this basic carbox yl ic acid and therefore exposure by ingestion is not the route of concern. Contact exposure may result in adverse effects to both plants and animals. Based on a qualitative review of the available information and the associated assumptions outlined in the sections below, it is EFED’s preliminary conclusion11 that the current labeled uses for p ropionic acid will not pose a significant risk to non - target organisms other than terrestrial plants.


### Anal ys is Plan Options Propionic acid is applied to crops post

- harvest. There are no ground or aerial applications. Based on the p ropionic acid use profile and the assumptions listed below EFED continues to believe that exposure to non

- target organisms will be extremely limited. Assumptions:

- Numerous uses occur indoors.

- When used outdoors, the product is applied simultaneously with baling activities. It is assumed that application during these activities will result in minimal spray drift off field because it is a contained operation. Small amounts of p ropionic acid may land in the field due to over spraying or windy conditions. If these assumptions are confirmed, a quantitative assessment will not be conducted. If it is found that the listed assumptions are not accurate, a quantitative assessment may be required. Anticipa ted Data Needs The Agency does not expect to requir e additional environmental fate studies but may require ecological effects studi es for plants, as listed in 40 CFR Part 158 prior to completing the Registration Review If a quantitative assessment is de emed necessary , seedling emergence and vegetative vigor data will be required to complete the assessment. The Agency will conduct a search of the open literature to ensure that all best available science is utilized. The Agency uses the ECOTOX database a s its mechanism for searching the open literature for ecological effects information. ECOTOX integrates three previousl y i ndependent databases

- AQUIRE, PHYTOTOX, and TERRETOX

- into a sy stem which includes toxicity data derived predominately from the peer - reviewed literature, for aquatic life, terrestrial plants, and terrestrial wildlife, respectivel y. Especiall y needed, in order to determine if a quantitative assessment is necessary, is information regarding the ty pical application process including methods, techniques and equipment. Several of the assumptions that preclude the necessity of a quantitative risk assessment are not included in the label but are based on assumed application practices. EFED is seeking answers to the following questions:12 1. Is p ropionic acid sprayed over large areas before a crop is harvested (ie

- corn)? 2. When p ropionic acid is applied during baling operations, does the method ensure that excess product (drips) is collected and not left on the field ? 3. Do outdoor application equipment and techniques usually prevent spray drift? The anal ys is plan will be revisited and may be revised depending upon the data available in the open literature and the information submitted by the public in response to the opening of the Registration Review docket.