UNITED STATES ENVIRONMENTAL PROTECTIO AGENCY 

WASHINGTON D.C., 20460 

OFFICE OF CHEMICAL 

SAFETY AND 

POLLUTION 

PREVENTION 

PC Code: 114401 , 114402 

DP Barcode: 426394 

Date: June 11, 2015 

MEMORANDUM 

SUBJECT: 

TO: 

FROM: 

REVIEWED 

BY: 

APPROVED 

BY: 

Registration Review: Preliminary Environmental Fate and Ecological Risk 

Assessment Endangered Species Effects Determination for Acifluorfen 

Lata Venkateshwara, Chemical Review Manager 

Tracy Perry, Team Leader 

Kelly Sherman, Acting Branch Chief 

Risk Management and Implementation Branch TII 

Pesticide Re-evaluation Division (7508P) ( I ,,..-

0 /J[ ~ ( // ~'~ Brian D. Kiernan, Biologist ·:;;.v 

Andrew Shelby. Physical Scientist~ ,,//)./' ~ // t/1SEnvironmental Risk Branch VI / - 0 

Environmental Fate and Effects Division (7507P) 

Monica Wait, Risk Assessment Process Leader 

Environmental Risk Branch VI 

Environmental Fate and Effects Division (7507P) 

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The Environmenlal Fate and Effects Division (EFED) has completed a preliminary risk assessment 

for lhe herbicide acifluorfen (PC Code I 1440 I, 114402). Risk conclusions can be found within 

the anached assessment but the following uncertainties should be noted. 

Uncertainties 

Reevaluation of seedling emergence is necessary and lack ofa frank vaJue for all species increases 

uncertainty in terrestrial plant assessment. 
2

The data for pollinators are incomplete; only an acute contact study is available for honey bees. 

This study does not result in an indication of risk, but as the newly required studies come in, 

potential risk to these taxa will be re-evaluated.

There are no LOC exceedances for aquatic invertebrates for any of the uses of acifluorfen. 

However, there are no available data for sediment dwelling species, which increases the 

uncertainty regarding potential effects to aquatic invertebrates. Parent acifluorfen does not 

trigger the requirement of sediment data as it degrades rapidly in anaerobic conditions. However, 

acifluorfen rapidly transforms in anaerobic conditions to amino acifluorfen which may be of 

comparable toxicity to acifluorfen according to structural activity toxicity estimates (ECOSAR). 

Therefore, exposure and toxicity to sediment dwelling species is an uncertainty.
3

Environmental Fate and Ecological Risk Assessment 

for the Registration Review of Acifluorfen

Acifluorfen

5-[2-Chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid

CAS Registry Number 50594-66-6

PC Codes 114401, 114402

Date: June 11, 2015

D426394

Prepared by:

Andrew Shelby, Physical Scientist, ERB VI

Brian D. Kiernan, Biologist, ERB VI

U. S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch IV

1200 Pennsylvania Ave., NW

Mail Code 7507P

Washington DC 20460

Reviewed by:

Monica Wait, RAPL, ERB VI

Mark Corbin, Branch Chief, ERB VI
4

Table of Contents

1. Executive Summary...............................................................................................................5

1.1. Nature of Chemical Stressor....................................................................................................................5

1.2. Risks to Non-target Organisms ...............................................................................................................5

1.3. Conclusions - Exposure Characterization ..............................................................................................6

1.4. Conclusions - Effects Characterization ..................................................................................................6

2. Problem Formulation ............................................................................................................7

2.1. Nature of Regulatory Action....................................................................................................................7

2.2. Stressor Source and Distribution ............................................................................................................7

2.2.1. Nature of Chemical Stressor................................................................................................................7

2.2.2. Overview of Pesticide Usage...............................................................................................................8

2.3. Receptors...................................................................................................................................................9

2.3.1. Aquatic and Terrestrial Effects............................................................................................................9

2.3.2. Ecosystems Potentially at Risk............................................................................................................9

2.4. Assessment Endpoints............................................................................................................................10

2.5. Conceptual Model ...................................................................................................................................10

2.5.1. Risk Hypotheses................................................................................................................................10

2.5.2. Conceptual Diagram..........................................................................................................................10

2.6. Analysis Plan...........................................................................................................................................12

2.6.1. Residues of Concern..........................................................................................................................12

2.6.2. Preliminary Identification of Data Gaps and Uncertainties...............................................................12

2.6.3. Multiple Active Ingredients, Mixtures and Formulated Products .....................................................13

2.6.4. Measures of Exposure .......................................................................................................................13

2.6.5. Measures of Effect.............................................................................................................................14

2.6.6. Integration of Exposure and Effects..................................................................................................15

3. Analysis.................................................................................................................................16

3.1. Use Characterization..............................................................................................................................16

3.2. Exposure Characterization....................................................................................................................17

3.2.1. Environmental Fate and Transport Characterization.........................................................................17

3.2.2. Measures of Aquatic Exposure..........................................................................................................19

3.2.3. Measures of Terrestrial Exposure......................................................................................................23

3.3. Ecological Effects Characterization......................................................................................................24

3.3.1. Aquatic Toxicity Assessment ............................................................................................................25

3.3.2 Terrestrial Effects Characterization...................................................................................................28

3.4. ECOTOX Open Literature ..........................................................................................................................30

4.0 Risk Characterization......................................................................................................30

4.1. Risk Estimation.......................................................................................................................................30

4.1.1. Aquatic Organisms............................................................................................................................31

4.1.2. Terrestrial Organisms........................................................................................................................34

4.2. Risk Description......................................................................................................................................38

4.2.1 Exposure to Aquatic Organisms........................................................................................................38

4.2.2 Risks to Aquatic Animals..................................................................................................................39

4.2.3 Risks to Aquatic Plants......................................................................................................................40

4.2.4. Risks to Mammals.............................................................................................................................41

4.2.5. Risk to Birds......................................................................................................................................41

4.2.6. Potential Effects to Terrestrial Invertebrates.....................................................................................42

4.2.7. Risk to Terrestrial Non-target Plants.................................................................................................42

4.3. Additional Uncertainties and Data Gaps..............................................................................................44

4.3.1. Fate and Transport.............................................................................................................................44

4.3.2. Effects................................................................................................................................................44

6. References.............................................................................................................................46
5

1. Executive Summary

1.1. Nature of Chemical Stressor

Registration review is currently underway for the herbicide sodium acifluorfen (sodium 5-(2-

chloro-a,a,a-trifluoro-p-tolyloxy)-2-nitrobenzoate; PC Code 114402) and acifluorfen free acid

(PC Code 114401). Sodium acifluorfen rapidly dissociates in water to acifluorfen free acid, and

therefore exposure and toxicity to both moieties will hereafter be referenced as "acifluorfen". 

Acifluorfen is a light dependent peroxidizing herbicide (LDPH). It has registered uses on 

soybean, peanuts, rice and strawberries with maximum single application rates up to 0.375 

pounds of active ingredient per acre (lb a.i./A) and maximum seasonal application rates as high 

as 0.75 lbs a.i./A.

1.2. Conclusions: Risks to Non-target Organisms

Terrestrial Plants. As expected with an herbicide, non-target terrestrial plants are likely to be 

adversely affected by exposure to acifluorfen. Grass species (Poaceae) in the available plant 

studies are considerably less sensitive than non-grass species (including non-grass monocots). 

RQs for upland, semi-aquatic and spray drift only are 3.6, 20 and 10 for the strawberry 

applications, although the LOC of 1.0 is exceeded for all use patterns. Additionally, the distance 

off the field at which spray drift alone (from aerial applications) results in an exceedance of the 

LOC greater than 1000 feet for both the strawberry and soybean/peanut use patterns and 643 feet 

for the rice use pattern.

Birds and Surrogates (Reptiles and Terrestrial Amphibians). Acute RQs exceed the RQ 

(0.5) for some size class/forage item combinations for the strawberry and soybean/peanut use 

patterns. However, there are no exceedances based on the subacute dietary endpoints. Chronic 

RQs exceed the LOC by up to 9-fold and exceed for all use patterns.

Mammals. Although there are no exceedances of the acute LOC, chronic exposure RQs exceed 

the LOC (1.0) by up to 4-fold (strawberry use).

Fish (and Aquatic-phase Amphibians). RQs for acute exposure to fish do not result in any 

exceedances. However, the chronic RQ, adjusted by the 29X LDPH factor exceed the LOC by 

6-fold for the rice use. The LDPH adjustment factor is discussed more fully in the body of the 

assessment.

Aquatic Invertebrates. There are no LOC exceedances for aquatic invertebrates for any of the 

uses of acifluorfen. However, there are no available data sediment dwelling species, which 

increases the uncertainty regarding potential effects to aquatic invertebrates.

Honey Bees and Terrestrial Invertebrates. The data for these taxa are incomplete; only an 

acute contact study is available for honey bees. This study does not result in an indication of 

risk, but as the newly required studies come in, potential risk to these taxa will be re-evaluated. 
6

Aquatic Plants. There are no LOC exceedances for aquatic plants for any of the uses of 

acifluorfen. No adverse effects to aquatic plants are expected based on the available data. 

1.3. Conclusions - Exposure Characterization 

Acifluorfen is expected to be persistent in both terrestrial and aquatic environments under 

aerobic and anaerobic conditions, and is considered mobile to moderately mobile, and 

nonvolatile. Acifluorfen is persistent in aerobic soil, with measured half-lives ranging from 100 

to 200 days. Acifluorfen is stable to hydrolysis and degrades readily via photolysis (t1/2 =15 

days). Acifluorfen does not bioconcentrate in aquatic organisms. Acifluorfen is expected to 

dissipate through spray drift, leaching, runoff, and anaerobic metabolism. Aquatic exposure 

estimates for acifluorfen are based on the exposure of the parent compound acifluorfen only. 

Inclusion of the only major degradate, amino acifluorfen, in a total toxic residue (TTR) approach 

results in less than a 10% increase in surface water EECs, would not impact risk conclusions and 

is, therefore, not included in risk estimation. Inclusion of amino acifluorfen in a TTR approach 

would significantly impact pore water/benthic concentrations but are not presented due to 

lacking toxicity data on sediment dwelling species. Acute 1-in-10 year estimated environmental 

concentrations (EECs) in surface water for all modeled uses of acifluorfen ranged from 9 μg/L to 

218 μg/L. Terrestrial animal exposure estimates are residue levels modeled by T-REX and 

parameterized with maximum application rates. Terrestrial plant exposures are based on parent 

acifluorfen alone (see Section 2.6.4). 

1.4. Conclusions - Effects Characterization 

Aquatic Organisms

Acifluorfen is slightly toxic to fish and aquatic invertebrates on an acute exposure basis. Effects 

were seen in fish and aquatic invertebrates from chronic exposure at concentrations of 1.0 mg 

ai/L and above. Because acifluorfen is an LDPH whose chronic toxicity to aquatic animals may 

be enhanced under high ultraviolet (uV) light, effects may be greater at higher altitudes or lower 

latitudes and in clear, shallow waters. Aquatic plants exhibited inhibition of biomass when 

exposed to acifluorfen.

Terrestrial Organisms

Acifluorfen is classified as moderately toxic to birds and slightly toxic to mammals on an acute 

exposure basis. A two-generation study on reproduction and fertility in the laboratory rat 

showed acifluorfen to cause chronic toxicity effects on parents (mortality) and pups (decreased 

weights). In birds, there were effects on number hatched/live embryo from chronic exposure.

No effects were reported from acute contact exposure to honey bees. 

As expected with an herbicide, effects on biomass and stand height were observed in terrestrial 

plant studies. The vegetative vigor exposure route (foliar spray) and life stage is generally more 

sensitive to acifluorfen than the seedling emergence exposure route (soil exposure) and life stage, 

based on the available studies. Sensitivity varies by species, with non-grasses are generally more 

sensitive than grasses.
7

2. Problem Formulation

The purpose of problem formulation is to provide the foundation for the environmental fate and 

ecological risk assessment for the registration review risk assessment for the herbicide sodium 

acifluorfen (sodium 5-(2-chloro-a,a,a-trifluoro-p-tolyloxy)-2-nitrobenzoate; PC Code 114402) and 

acifluorfen free acid (PC Code 114401). As mentioned previously, sodium acifluorfen rapidly 

dissociates in water to acifluorfen free acid, and therefore exposure and toxicity to both moieties 

will hereafter be referenced as "acifluorfen". Acifluorfen is a non-selective, post-emergent 

contact herbicide used to control annual broadleaf weeds and some grasses in soybean, peanuts, 

rice and strawberries. The problem formulation sets the objectives for the risk assessment, 

establishes a risk hypothesis and conceptual model depicting potential risk, and provides a plan 

for analyzing the data and characterizing the risk associated with the uses of acifluorfen

(USEPA, 1998). This preliminary ecological risk assessment draws primarily from the Problem 

Formulation published in 2010 (DP 370340; 3/24/2010; available at regulations.gov in the public 

docket EPA-HQ-OPP-2010-0135-0003). Data submitted after the Problem Formulation are 

described in this assessment and used when appropriate.

2.1. Nature of Regulatory Action

The U.S. Environmental Protection Agency (EPA or the Agency) is required under the Federal 

Insecticide, Fungicide, and Rodenticide Act (FIFRA) to ensure that the currently registered 

pesticide acifluorfen remains eligible for registration, and that it does not have the potential to 

cause unreasonable adverse effects to the environment. This assessment follows EPA guidance 

on conducting ecological risk assessments (USEPA, 1998) and, generally, the Office of Pesticide 

Program’s Overview Document, which contains guidance for assessing pesticide risks to nontarget organisms (USEPA, 2004). Section 5 summarizes the Agency’s current approach to 

assessing risks from acifluorfen to Federally-listed threatened and endangered (hereafter “listed”) 

species.

The end result of the EPA pesticide registration review process (i.e., the FIFRA regulatory 

action) is an approved product label. The label is a legal document that stipulates how and where 

a given pesticide may be used. Product labels (also known as end-use labels) describe the 

formulation type (e.g., liquid or granular), acceptable methods of application, approved use sites, 

and any restrictions on how applications may be conducted. Therefore, the uses, or potential 

uses, described by the pesticide’s labels are considered “the action” being assessed. This 

assessment was prepared to support evaluation of the registration review of acifluorfen. 

2.2. Stressor Source and Distribution

2.2.1. Nature of Chemical Stressor

Acifluorfen is a light dependent peroxidizing herbicide (LDPH). LDPHs are a class of weed 

control chemicals that act in plants by inhibiting the enzyme protoporphyrinogen oxidase 

(protox), which is the last common enzyme in the heme and chlorophyll biosynthetic pathways. 

Protox exists in both plants and animals, and the enzyme from both sources has been shown to be 
8

sensitive to many LDPHs. Acifluorfen is also known as polyphenol oxidase (PPO) inhibitor, in 

this case a diphenyl ether.

Acifluorfen is registered for use on soybean, peanuts, strawberries (annual and perennial) and

rice. This assessment is based on currently labeled maximum application rates for all uses. 

Maximum annual application rates range from 0.25 lb a.i./A (rice) to 0.75 lb a.i./A 

(strawberries). Specific use rates are discussed in Section 3.1.

These uses are not the only source of acifluorfen in the environment. Lactofen (PC Code 

128888), a unique pesticide active ingredient, rapidly metabolizes in aerobic soil (t1/2 = 1 to 3 

days) with the most significant major metabolite being acifluorfen (50% by mass). Acifluorfen 

and lactofen share some of the same registered uses including soybeans and peanuts for national 

Section 3 registrations. Acifluorfen is nationally registered for use on strawberries while 

lactofen is registered for strawberries in Oregon only with a Section 24c special local needs 

registration. For these common use sites, concentrations of acifluorfen may be higher than what 

is estimated in this assessment if an applicator applies different products containing both of these

active ingredients to the same area.

2.2.2. Overview of Pesticide Usage

Although registered product labels indicate potential use of acifluorfen, usage data confirms that 

use is occurring in the field and allows for characterization of trends in use of acifluorfen over 

time at a national scale. Data are derived from USDA National Agricultural Statistics Service, 

private pesticide market research, and the California Department of Pesticide Regulation. Usage 

data are summarized in Table 2.1.

Table 2.1. Screening Level Usage Estimates of Agricultural Uses of Acifluorfen as of July 7, 

2014

Average Annual 

Usage Percent Crop Treated

Crop Lbs. A.I. Average Maximum

Peanuts 50,000 15 20

Rice 20,000 5 10

Soybeans 80,000 <1 <2.5

Strawberries <500 <1 <2.5

Soybeans, peanuts and rice are the dominant use pattern for acifluorfen. Usage on strawberries 

has been comparatively minor. 
9

2.3. Receptors

2.3.1. Aquatic and Terrestrial Effects

In ecological risk assessment, a receptor is a biological entity that is exposed to a stressor 

(USEPA, 1998). Consistent with the process described in the Overview Document (USEPA, 

2004), this risk assessment uses a surrogate species approach in its evaluation of acifluorfen. 

Toxicity data generated using surrogate test species, which are intended to be representative of 

broad taxonomic groups, are used to infer potential effects on a variety of species (receptors) 

included under these broader taxonomic groupings. Table 2.2 provides the general taxonomic 

groups and surrogate species tested to evaluate potential ecological effects of acifluorfen to 

broad classes of non-target organisms. Within each of these taxonomic groups, a measure of 

effect is selected from among the available test data. 

Table 2.2. Taxonomic Groups and Test Species Evaluated for Assessing Potential 

Ecological Effects of Acifluorfen.

Taxonomic Group Typical Species

Birds1 Mallard duck (Anas platyrhynchos)

Bobwhite quail (Colinus virginianus)

Mammals Norway rat (Rattus norvegicus)

Invertebrates Honey bee (Apis mellifera L.)

Freshwater fish2 Bluegill sunfish (Lepomis macrochirus)

Rainbow trout (Oncorhynchus mykiss)

Fathead minnow (Pimephales promelas)

Freshwater invertebrates Water flea (Daphnia magna)

Midge (Chironomus riparius)

Estuarine/marine fish Sheepshead minnow (Cyprinodon variegatus)

Estuarine/marine invertebrates Mysid (Americamysis bahia)

Eastern oyster (Crassostrea virginica)

Terrestrial plants3 Monocots – Crop species, such as corn (Zea mays)

Dicots – Crop Species, such as soybean (Glycine max)

Aquatic plants and algae Duckweed (Lemna gibba) 

Freshwater Algae (Pseudokirchneriella subcapitata) 1 Birds serve as surrogates for terrestrial-phase amphibians and reptiles. 2 Freshwater fish may be surrogates for aquatic-phase amphibians. 3 Four species of two families of monocots, of which one is corn; six species of at least four dicot families, of 

which one is soybeans. A root crop is required.

2.3.2. Ecosystems Potentially at Risk 

The ecosystems potentially at risk are often extensive in scope; therefore, it may not be possible 

to identify specific ecosystems during the development of a nation-wide ecological risk 

assessment. However, in general terms, terrestrial ecosystems potentially at risk could include 

the treated field and immediately adjacent areas that may receive drift and/or runoff. Areas 

adjacent to the treated field could include cultivated fields, fencerows and hedgerows, meadows, 

fallow fields or grasslands, woodlands, riparian habitats, and other uncultivated areas. 

Aquatic ecosystems potentially at risk include water bodies adjacent to or downstream from use 
10

sites, and might include lentic bodies such as ponds, lakes and reservoirs, or lotic (flowing)

waterways such as streams or rivers as well as adjacent off-channel habitats that may be

permanently or intermittently connected to flowing waters. For uses in coastal areas, aquatic 

habitat also includes marine ecosystems, estuaries, embayments, and near-shore environments 

such as tidal marshes.

2.4. Assessment Endpoints

Assessment endpoints represent the actual environmental value that is to be protected, defined by 

an ecological entity (e.g., species, community) and its attribute or characteristics (USEPA, 1998). 

For acifluorfen, ecological entities of potential concern include the following: birds, amphibians, 

reptiles, mammals, freshwater fish and invertebrates, estuarine/marine fish and invertebrates, 

non-target terrestrial plants, terrestrial invertebrates, and aquatic vascular and non-vascular 

plants. The attributes for each of these entities may include growth, survival, and reproduction 

(Table 2.3 in Section 2.6.5).

2.5. Conceptual Model

For a pesticide to pose an ecological risk, it must reach ecological receptors in biologically 

significant concentrations. An exposure pathway is the means by which a pesticide moves in the 

environment from a source to an ecological receptor. For an ecological pathway to be complete, 

it must have a source, a release mechanism, an environmental transport mechanism, and a 

feasible route of exposure.

The conceptual model is intended to provide a written description and visual representation of 

anticipated relationships between acifluorfen, potential routes of exposure, and the predicted 

effects for the assessment endpoints. The conceptual model consists of two major components: 

risk hypotheses and a conceptual diagram (USEPA, 1998).

2.5.1. Risk Hypotheses

For acifluorfen, the following generic ecological risk hypothesis is being employed for this 

screening-level risk assessment:

Given the currently labeled uses of acifluorfen and its environmental fate properties, 

there is a likelihood of exposure to non-target terrestrial and aquatic organisms. 

When used in accordance with the label, acifluorfen may result in adverse effects upon 

the survival, growth, and reproduction of non-target terrestrial and aquatic organisms. 

2.5.2. Conceptual Diagram

The conceptual model is a graphical representation of predicted relationships between ecological 

receptors, both listed (threatened and endangered) and non-listed, and the stressors to which they 

may be exposed. A conceptual model specifies potential routes of exposure, biological receptor 

types, and effects endpoints of potential concern. 
11

Acifluorfen is applied as either a pre- or post-emergence herbicide. Figure 2.1 depicts the 

stressors, exposure pathways, and potential effects to terrestrial organisms from currently labeled

uses of acifluorfen. Figure 2.2 depicts the stressors, exposure pathways, and potential effects to 

aquatic organisms from currently labeled uses of acifluorfen. For both figures, dotted lines 

indicate exposure pathways that are expected to have a low likelihood of contributing to 

ecological risk. 

 

 

Figure 2.1. Conceptual model for acifluorfen effects on terrestrial organisms.

Stressor

Source

Receptors

Attribute

Change

Acifluorfen applied to use site

Direct 

Application/Spr

ay Drift

Birds / Terrestrialphase amphibians 

/ reptiles / 

mammals

Seeds

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in prey

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Terrestrial/riparian plants

grasses/forbs, fruit, terrestrial 

invertebrates 

Runoff

Mammals

Exposure

Media

Soil

Ingestion

Ingestion

Ingestion

Ingestion

Dermal uptake/Ingestion

Root uptake

Wet/dry deposition

Birds / 

Amphibians

Ingestion
12

Figure 2.2. Conceptual model for acifluorfen effects on aquatic organisms.

2.6. Analysis Plan

2.6.1. Residues of Concern

Acifluorfen is relatively stable in the environment; no degradates or transformation products of 

environmental concern have been identified. However, acifluorfen rapidly degrades to the 

persistent degradate amino acifluorfen in anaerobic environments. Amino acifluorfen is not 

considered in risk estimation but inclusion as a toxic residue with acifluorfen is considered in 

risk characterization.

2.6.2. Preliminary Identification of Data Gaps and Uncertainties 

With only one aerobic aquatic metabolism study and one anaerobic aquatic metabolism study 

available, a 3X adjustment is made to each half-life to conservatively account for the expected 

variability associated with those parameters and in accordance with EFED input parameter 

guidance. Additional aerobic and anaerobic aquatic metabolism data on varied aquatic systems 

are likely to reduce the associated input parameters since the 90th percentile upper confidence limit 

Stressor

Source

Receptors

Attribute

Change

Acifluorfen applied to use site

Fish/aquatic-phase 

amphibians

Eggs 

Larvae 

Juveniles / Adults

Individual organisms

Reduced survival

Reduced growth

Reduced reproduction

Food chain

Reduction in algae

Reduction in prey

Habitat integrity

Reduction in primary productivity

Reduced cover

Community change

Surface water/

Sediment

Runoff

Aquatic Animals

Invertebrates

Vertebrates

Exposure

Media

Uptake/gills 

or integument

Ingestion Ingestion

Wet/dry deposition

Soil Groundwater

Uptake/gills 

or integument

Aquatic Plants

Non-vascular

Vascular

Uptake/cell, 

roots, leaves Riparian plant

terrestrial 

exposure 

pathways see 

Figure 2.1

Spray Drift
13

on the mean half-life of all available metabolism studies is typically used as the input parameter

(although it is possible that additional data would indicate a longer half-life).

As previously stated, LDPHs are a class of weed control chemicals that act in plants by 

inhibiting the enzyme protoporphyrinogen oxidase (protox), which is the last common enzyme in 

the heme and chlorophyll biosynthetic pathways. Protox exists in both plants and animals and 

the enzyme from both sources has been shown to be highly sensitive to many LDPHs. Several 

studies have documented enhanced toxicity of LDPHs to fish in the presence of uV light 

compared to toxicity observed under standard laboratory lighting. Given that aquatic organisms 

are likely to be exposed simultaneously to LDPH and uV light in natural settings, concerns have 

been raised that guideline chronic exposure laboratory tests may underestimate the toxicity of 

LDPHs in the field. In the absence of chemical-specific data on LDPH toxicity under enhanced 

uV lighting and until the analysis of the toxicity testing conducted by the LDPH Task Force is 

complete, the Agency is applying an interim adjustment factor of 29X to adjust no observed 

adverse effect concentration (NOAEC) values to account for the potential enhanced toxicity of 

LDPH chemicals under natural sunlight (USEPA 2010a). This enhanced sensitivity to LDPHs is 

not necessarily limited to fish and could be observed in other taxa such as aquatic invertebrates, 

birds, and mammals (Birchfield and Casida, 1997); however, the Agency is only applying an 

adjustment factor to fish at this time. 

2.6.3. Multiple Active Ingredients, Mixtures and Formulated Products

The Agency does not routinely include in its risk assessments an evaluation of mixtures of active 

ingredients, either those mixtures of multiple active ingredients in product formulations or those 

in the applicator’s tank. In the case of multiple a.i. formulated products (that is, a registered 

product containing more than one active ingredient), each active ingredient is subject to an 

individual risk assessment for regulatory decision regarding that active ingredient on a particular 

use site. If effects data are available for a formulated product containing more than one active 

ingredient, they may be used qualitatively or quantitatively in accordance with the Agency’s 

Overview Document (U.S. EPA 2004). Data on multiple a.i. product formulations was not 

discovered for acifluorfen.

2.6.4. Measures of Exposure 

Measures of exposure are based on aquatic and terrestrial models that estimate environmental 

concentrations of acifluorfen using labeled application rates and methods. For aquatic 

exposures, the Tier II model Surface Water Concentration Calculator (SWCC v1.106) was used 

to estimate screening-level exposure concentrations in aquatic environments. The measure of 

exposure for aquatic species in surface water bodies receiving runoff and/or spray drift is a return 

frequency of 1-in-10 years of the estimated environmental concentrations (EEC), based on 30-

year simulations. The maximum 1-in-10 year return frequency concentration is used for 

estimating acute exposures to aquatic organisms (plants and animals); the 1-in-10 year 21-day 

mean concentration is used for assessing aquatic invertebrate chronic exposure; and the 1-in-10 

year 60-day mean concentration is used for assessing chronic exposure for fish (and aquaticphase amphibians for which fish serve as surrogates). 

Terrestrial exposure estimates for avian and mammalian risk assessments were derived using the 
14

T-REX model (version 1.5.2). T-REX is used to calculate dietary- and dose-based EECs of 

acifluorfen for birds (and surrogates) and mammals inhabiting terrestrial areas. T-REX 

simulates a 1-year time period. The default foliar dissipation half-life of 35 days (Willis and 

McDowell 1987) is used as input to T-REX, when chemical-specific data are not available; these 

data were not available for acifluorfen. 

Exposure for terrestrial plants inhabiting dry and semi-aquatic areas (e.g., low-lying wet areas 

that may dry up at times throughout the year), using TerrPlant v 1.2.2, is based on the following:

(1) the pesticide's water solubility and the amount of pesticide present on the soil surface 

and its top one centimeter,

(2) potential "sheet runoff" (one treated acre to an adjacent acre) for dry areas,

(3) potential "channel runoff" (10 acres to a distant low-lying acre) for semi-aquatic or 

wetland areas,

(4) fractional runoff values of 0.01, 0.02, and 0.05 for pesticide water solubilities of <10, 

10-100, and <100 ppm, respectively

(5) drift assumption of 1% for ground and 5% for aerial application

AgDRIFT (v 2.01) is used to refine drift exposure to terrestrial plants, providing an estimate of 

the area of concern for these taxa surrounding the area of application.

2.6.5. Measures of Effect

Measures of effect are obtained from a suite of registrant-submitted guideline studies that were 

conducted with a limited number of surrogate test species (Table 2.2). No data regarding more 

sensitive endpoints for the apical endpoints used in this risk assessment were identified in a

January 2015 ECOTOX search conducted by the Office of Research and Development in Duluth 

for EFED. 

The acute measures of effect used in this screening-level assessment are the LD50 (median Lethal 

Dose), LC50 (median Lethal Concentration) or EC50 (median Effects Concentration). These are 

measures of acute toxicity which result in 50% of the respective effect in tested organisms. The 

endpoints for chronic measures of exposure are generally the no observed adverse effect 

concentration (NOAEC) and the no observed adverse effect level (NOAEL). For plants, the 

EC25 or IC25 (inhibition concentration) and NOAEL are used as assessment endpoints. Toxicity 

studies were submitted for freshwater fish and invertebrates, estuarine/marine fish and 

invertebrates, aquatic plants, birds, mammals, bees, and terrestrial plants. The endpoints used for 

risk characterization are derived from studies which underwent review and were classified as 

“acceptable” (conducted under guideline conditions and considered to be scientifically valid) or 

“supplemental” (conditions deviated from guidelines but the results are considered to be 

scientifically valid). 

Table 2.3 lists the measures of environmental exposure and ecological effects used to assess the 

potential risks of acifluorfen to non-target organisms. 
15

Table 2.3. Measures of Exposure and Measures of Effect Used in Assessing Potential Risks 

Associated with the Currently labeled Uses of Acifluorfen.

Assessment Endpoint Surrogate Species and Measures of 

Ecological Effect1 Measures of Exposure

Birds2

Survival

Lowest acute LD50 (single oral dose test) 

and LC50 (subacute dietary test)

Upper-bound residues on 

food items

Reproduction 

and Growth

Lowest NOAEC

(21-week reproduction test)

Mammals

Survival Lowest acute LD50 (single oral dose test)

Reproduction 

and Growth

Lowest NOAEC 

(2-generation reproduction test)

Aquatic Animals (Fish and 

invertebrates)3

Survival Lowest tested LC50 or EC50

(acute toxicity test)

Peak EECs4

Reproduction 

and Growth

Lowest NOAEC (early life-stage or full 

life-cycle tests)

21-day EECs for invertebrates 

and 60-day EECs for fish4

Terrestrial plants5 Survival and 

growth

Lowest IC25 (for non-listed plants) and 

corresponding NOAEC (for listed 

plants)

(endpoints derived for monocots and 

dicots from seedling emergence and 

vegetative vigor studies)

Estimates of runoff and spray 

drift to non-target areas

Insects6 Survival (not 

quantitatively 

assessed)

Lowest honeybee LD50 (acute contact 

test)

Maximum application rate for 

honeybees and estimates of 

soil concentrations for 

earthworms 

Aquatic plants (vascular 

and non-vascular)

Survival and 

growth

Lowest IC50 (for non-listed plants) and 

corresponding NOAEC or EC05 (for 

listed plants)

Peak EECs4

1 The most sensitive species tested within taxonomic groups is used for screening-level risk assessments. 2 Birds represent surrogates for terrestrial-phase amphibians and reptiles. 3 Freshwater fish represent surrogates for aquatic-phase amphibians. 4 Aquatic EECs are based on modeling described in Section 3.2.2.1. 5 Four species of two families of monocots - one is corn, six species of at least four dicot families, of which one is 

soybeans.

6 Risk to terrestrial invertebrates from acifluorfen use is not evaluated, rather the potential hazard to honey bees (i.e. the 

available data) are qualitatively assessed.

2.6.6. Integration of Exposure and Effects

Exposure and toxicity data are integrated in order to evaluate the risks of adverse ecological 

effects on non-target species. For the screening-level risk assessment of acifluorfen, the 

deterministic risk quotient (RQ) method is used to compare estimated exposure concentrations 

(EECs) with measured toxicity values. The RQ method involves dividing point estimates of 

environmental concentrations by acute and chronic toxicity values. The resulting unitless RQs 

are then compared to the Agency’s Levels of Concern (LOC) (USEPA, 2004) (Table 2.4). These 

criteria are used to indicate when applications of acifluorfen, as directed on the current product 

labels, have the potential to cause adverse effects to listed and non-listed non-target organisms.
16

Table 2.4. Agency Risk Quotient (RQ) Metrics and Levels of Concern (LOC) Per Risk 

Class.

RISK CLASS RISK DESCRIPTION RQ LOC

Aquatic Animals (fish and invertebrates)

Acute Potential for effects to non-listed animals from acute 

exposures

Peak EEC/LC501 0.5

Acute Listed

Species

Listed species may be potentially affected by acute 

exposures

Peak EEC/LC501 0.05

Chronic Potential for effects to non-listed and listed animals from 

chronic exposures

60-day EEC/NOAEC 

(fish) 1

21-day EEC/NOAEC 

(invertebrates)

Aquatic Plants

Non-Listed Potential for effects to non-listed plants from exposures Peak EEC/LC501 1

Listed Potential for effects to listed plants from exposures Peak EEC/NOAEC 1

Terrestrial Animals (mammals, birds and invertebrates)

Acute Potential for effects to non-listed animals from acute 

exposures

EEC2/LC50 (Dietary) 0.5

EEC/LD50 (Dose)

Acute Listed 

Species

Listed species may be potentially affected by acute 

exposures

EEC2/LC50 (Dietary) 0.1

EEC/LD50 (Dose)

Chronic Potential for effects to non-listed and listed animals from 

chronic exposures EEC 2

/NOAEC 1

Terrestrial and Semi-Aquatic Plants

Non-Listed Potential for effects to non-target, non-listed plants from 

exposures

EEC/ EC25 1

Listed Potential for effects to non-target, listed plants from 

exposures

EEC/ NOAEC

1

EEC/ EC05

1 LC50 or EC50. 

3. Analysis

3.1. Use Characterization

Acifluorfen can be applied pre-plant, pre-emergence, post-emergence, or as a burndown

treatment depending on the specific label language for a given use pattern. Early season 

applications conservatively represent burndown applications because application rates remain the 

same regardless of timing and the early season has more rainfall. Acifluorfen can be tank mixed 

with several other herbicides for either broadleaf or grass-specific control, depending on the 

objective.

Acifluorfen may be used on annual and perennial strawberries. It may be used on strawberries as 

a pre-plant spray for annuals or a post-emergence spray for perennials at up to 0.375 lb a.i./A for 

a single application with two applications per year (15 day minimum reapplication interval).
17

Use patterns for acifluorfen are presented in Table 3.1.

Table 3.1. Use patterns and use rates for acifluorfen.

Crop Registration (application timing)

Max single 

application

Max season 

application

Minimum 

retreatment 

interval 

(days)

Peanuts Pre- and post-emergence 0.375 0.5 15

Soybeans Post-emergence and burndown 0.375 0.5 15

Strawberries -

perennial Post-emergent 0.375 0.75 15

Strawberries -

annual Pre-plant 0.375 0.75 15

Rice Post-emergent 0.25 0.25 15*

* Multiple applications are allowed (if a lower than maximum single application rate is used during the first 

application), but the seasonal maximum application rate is 0.25 lbs a.i./A

3.2. Exposure Characterization

3.2.1. Environmental Fate and Transport Characterization

The general physical/chemical properties of acifluorfen are summarized in Table 3.2. 

Environmental fate and transport-related properties of acifluorfen are characterized in further 

detail in the following sections. The Agency’s understanding of these properties is informed by 

the available dataset. Many of the chemical properties and environmental fate parameters of 

acifluorfen listed in Table 3.2 are based on studies classified as supplemental due to 

uncertainties or minor deviations from the test guideline.

Table 3.2. General Physical-Chemical and Environmental Fate Properties of Acifluorfen

Input Parameter Value Source/comment

Molecular weight 361.66 g/mol

Vapor pressure <1E-7 torr @ 25 oC 41784601

Solubility in water 620.7 g/L @ 20C

Octanol-Water Partition Coefficient 1.55 at pH 7 41891206

Hydrolysis half-life Stable 00071584

00122757

00107479

Aqueous Photolysis half-life 21.7 to 352 hours 41891208

42793502

44195001

44195002

Aerobic Soil metabolism half-life 100 days

108 days

193 days

200 days

00143572
18

Input Parameter Value Source/comment

Anaerobic aquatic metabolism halflife2.75 days 43155201

Water-clay soil system under N2

atmosphere, amino acifluorfen persisted 

through 375 day incubation

Aerobic Aquatic metabolism half-life 114 days 42330601

Extrapolated 35 day study

Organic carbon normalized soil 

partition coefficient Koc

50, 57, 74, 165, 199 mL/g o.c. 42793501

Henry’s Law Constant 7.65 *10-10 atm-m3

/mol Calculated from vapor pressure and 

solubility

Laboratory studies

Acifluorfen is persistent in soil (aerobic soil metabolism half-life of 170 days) and in aerobic 

aquatic environments (estimated aerobic half-life of 117 days); it is less persistent in anaerobic 

conditions (aquatic half-life estimated to be 2.75 days). Acifluorfen is relatively mobile; Kds 

range from 0.148 to 3.10 g/mL. Adsorption and desorption were strongly correlated with soil clay 

content, organic carbon content, and cation exchange capacity. Acifluorfen undergoes photolytic 

degradation in water with half-lives ranging from 21.7 hours to 352 hours.

Thus acifluorfen may degrade rapidly in surface water bodies with clear and/or shallow water 

that is able to transmit adequate light. It is stable to hydrolysis, and photodegradation on soil is 

not a major degradation route in the environment. Volatilization does not appear to be a 

significant dissipation pathway for acifluorfen (vapor pressure is <1E-7 torr; Henry's Law 

constant is 7.65 x 10-10 atm m3/mol). Acifluorfen is not expected to bioaccumulate in aquatic 

organisms because of the low Kow.

Field studies

Available field studies for acifluorfen are summarized in Table 3.3.

Table 3.3. Field studies available for acifluorfen.

Study Value Comments Source

Terrestrial Field 

Dissipation (Half-life)

15 days

59 days

After 2 months, residue 

levels were near detection 

levels Mississippi silt 

loam; leaching below 3-in 

depth negligible during 

179 days of study

00137756,

00143573

Aquatic Field Dissipation 

(Half-life)

2.2-17.2 days In unvegetated rice fields 

in Mississippi and 

Louisiana

43270801

Small scale prospective 

ground water study

Detected in ground water 

at up to 46 ppb

Acifuorfen residues 

detected in suction 

lysimeters and in ground 

41172801
19

Study Value Comments Source

water in a soybean field in 

Wisconsin

Small scale retrospective 

ground water study

Residues leached through 

soil profile and under 

certain

conditions were detected 

in

ground water

Five states: North 

Carolina, North Dakota, 

Indiana, Tennessee, and 

Virginia

41160001,

41409501,

41458901,

41644901,

41833202,

42152201

3.2.1.5. Environmental Degradates

The primary degradate of acifluorfen under anaerobic conditions was the corresponding amine from 

the reduction of the nitro group (amino acifluorfen (5-[2-chloro-4(trifluoromethyl) phenoxy]-2-

aminobenzoic) acid). When samples were incubated under anaerobic conditions for up to 375 

days, the degradates amino acifluorfen, acifluorfen acetamide (5-[2-chloro-4-(trifluoromethyl) 

phenoxy]- 2-acetamidobenzoic acid), and desnitro acifluorfen (3-[2-chloro-4-(trifluoromethyl)

phenoxy]- benzoic acid) were identified in the soi1:water systems. Amino acifluorfen averaged 

64 -71% of the radioactivity applied at 25 through 375 days; maximum concentrations of the other 

degradates were <5% throughout the study. These same three degradates were seen in the other 

metabolism studies; however, none were present at greater than 5% of the applied radioactivity. The 

amino acifluorfen degradate is less mobile than the parent; Kds range from 1.25 to 47 g/mL.

Adsorption and desorption were strongly correlated between Kads and soil pH, with an increase in 

sorption corresponding to a decrease in pH. For sand, clay and loam soils a correlation existed 

between Kads and percent organic matter; however, this relationship did not hold for loamy sand 

soil. The loamy sand, however, had the highest level of sorption and the lowest pH value. This 

indicates that soil pH may have a stronger effect on sorption than organic matter. A correlation 

was not observed for % clay.

3.2.2. Measures of Aquatic Exposure

3.2.2.1. Surface Water Exposure to Acifluorfen

The Tier II model Surface Water Concentration Calculator (SWCC, v1.106) was used to estimate 

screening-level exposure concentrations in aquatic environments. The model simulates pesticide 

movement and transformation on and transport from an agricultural field resulting from crop 

applications. It subsequently simulates pesticide concentrations in water due to loading via 

runoff, erosion, and spray drift, assuming a standard 1-ha pond, 2-m deep (20,000 m3

) with no 

outlet that borders a 10-ha treated field. Simulations are for 30 years, from which the Agency 

estimates peak values that are expected to recur on average once every ten years, based on time 

series of daily estimated concentrations. SWCC and user’s manual are available from the U.S. 

Environmental Protection Agency Water Models web-page (USEPA, 2015).

The Pesticides in Flooded Applications Model (PFAM, v1.104) was developed to facilitate risk 

assessments for pesticides used in flooded-agriculture applications such as rice paddies and 

cranberry bogs. PFAM was designed around the specific parameters that are typically available 
20

for a pesticide risk assessment, thereby simplifying the assessment process. The model makes 

use of fate properties of pesticides and allows for the specification of common management 

practices that are associated with flooded agriculture such as scheduled water releases and 

refills. It also allows for natural water level fluctuations resulting from precipitation and 

evapotranspiration.

Exposure estimates generated using the standard pond are intended as surrogates for potential 

concentrations in a wide variety of vulnerable water bodies, including prairie potholes, playa 

lakes, vernal pools, other wetlands, man-made and natural ponds, and ephemeral and first-order 

streams. Innumerable site-specific factors may make such water bodies more or less vulnerable 

than the standard pond. Static water bodies that have larger ratios of pesticide-treated drainage 

area to water body volume are generally expected to experience higher peak concentrations than 

the standard pond’s EECs. Such water bodies may be smaller in size, and/or have larger 

drainage areas, which will tend to result in higher concentrations. However such water bodies 

may also overflow at least occasionally and thus discharge pesticide in their effluent (unlike the 

standard pond, which is assumed to have no discharge), which will tend to result in lower 

concentrations.

As watershed size increases, it becomes increasingly unlikely that the entirety of a watershed is 

planted with a single crop that is all treated simultaneously with a pesticide. Headwater streams 

may have peak concentrations that are higher than those predicted for the standard pond, but 

such concentrations will likely persist for only short periods of time or distance, as they are 

carried downstream and diluted with water originating elsewhere.

The general chemical and environmental fate data for acifluorfen listed in Table 3.2 were used 

for generating model input parameters for SWCC (listed in Table 3.4). Chemical specific and 

model input values were chosen in accordance with current EFED guidance (USEPA, 2009). 

Table 3.4. SWCC, PRZM-GW, and PFAM input parameter values for acifluorfen use on 

peanuts, soybeans, strawberries, and rice.

PARAMETER (units) VALUE(S) SOURCE COMMENT

Application Rate (kg a.i./ha) 1st application 

peanuts, soybeans 

and strawberries = 

0.42

2nd application 

strawberries = 0.42

2nd application 

peanuts and 

soybeans = 0.14

Maximum Rates

Peanuts, soybeans (1st) and 

strawberries (1st and 2nd) = 0.375 lb 

a.i./ac

Peanuts, soybeans (2nd) = 0.125 lb 

a.i./ac

Reapplication Interval (days) 15

Number of Applications 2
21

PARAMETER (units) VALUE(S) SOURCE COMMENT

Molecular weight (g/mol) 361.66

Henry’s Law Constant (atmm3

/mol)

7.65*10-10 Calculated from vapor pressure and 

solubility

Vapor Pressure (torr@ 25 oC) <1*10-7 41784601

Solubility in Water @ 20 OC, 

(mg/L or ppm)

620,000

Organic Carbon Soil Partition 

Coefficient (mL/g o.c.)

KOC = 109 42793501 Mean of five KOC values: 50, 57, 74, 

165, 199

Chemical Application Method Ground ground spray; pre-plant or preemergence, post-emergence, 

unincorporated

Depth of Incorporation (inches) 0 –

Application efficiency (decimal) 0.95 Aerial application permitted on label 

Spray drift fraction (decimal) 0.125

Retreatment Interval (days) 15

Date of initial application Peanuts: 15 days 

pre-emergence

Soybeans: 15 days 

pre-emergence

Annual strawberries: 

30 days preemergence

Peanuts: pre- and post-emergent

Soybeans: pre-plant, post-emergence, 

or post-harvest (early season 

applications conservatively represent 

burndown applications as early 

season has more rainfall)

Annual strawberries: pre-plant

Perennial strawberries: postemergence

Rice: post-emergent

Hydrolysis Half-life (days) Stable 00071584

00122757

00107479

Aqueous Photolysis Half-life @ 

pH 7 (days)

14.7 days 44195002

Aerobic Aquatic Metabolism 

Half-life (days)

114 days 42330601 3X one aerobic aquatic metabolism 

half-life per Input Parameter 

Guidance1
22

PARAMETER (units) VALUE(S) SOURCE COMMENT

Anaerobic Aquatic Metabolism 

Half-life (days)

8.25 43155201 Parent anaerobic soil metabolism 

half-life = 2.75 days. Input is 3X 

half-life considering one value is 

available

Aerobic Soil Metabolism Halflife (days)173 00143572 Upper 90% confidence limit on mean 

of 4 values: 100 days, 108 days, 193 

days, and 200 days

1 “Input Parameter Guidance” refers to Guidance for Selecting Input Parameters in Modeling the Environmental Fate 

and Transport of Pesticides; Version 2.1, October 22, 2009. 

Inputs in Table 3.5 are specific to PFAM parameterization. Inputs relevant to both PFAM and 

SWCC are summarized in Table 3.4.

Table 3.5. PFAM Inputs Specific Acifluorfen

Input Parameter Value Source Comment

Application rate 0.25 lbs 

a.i./A

Number of 

Applications per Year 1 --- ---

Application dates 8-18 ---

Slow Release 1/day 0 -- No flow conservatively assumed

Drift Application 0 -- Drift not applicable for Tier 1 in the paddy 

concentrations 

Flood Tab

Number of Flood 

Events 2 --

Flooding to 4 inches. Initial flood date selected to 

precede planting in Arkansas and California1

Date of Event 1 

(Month-Day) 5-1 --

Turn Over (1/day) 0 Assumed

Days After 

Fill Level, 

Min Level 

(m)

Wier (m)

0 0.1016 0.1270

140 0 0

1 - http://www.uaex.edu/publications/pdf/mp192/chapter-2.pdf (Accessed April 23, 2015)
23

The modeled aquatic EECs resulting from the currently labeled acifluorfen uses were used for 

risk estimation in this assessment (Table 3.8). Representative scenarios for labeled uses were 

modeled. For pre-emergence applications, an initial application date approximately two weeks 

prior to emergence was selected. Small alterations in initial application date do not reflect a 

substantial change in the use pattern modeled but can significantly impact EECs. Peak, 21-day 

average and 60-day average concentrations are driven by the weather patterns occurring during 

and after the application as reflected in 30-year meteorological file geographically relevant to a 

given SWCC scenario. An alteration to the initial application of two to three days may include 

several rain events not captured otherwise. Such rain events would increase EECs providing a 

more conservative estimate. 

Table 3.6. Modeled Aquatic Surface Water 1-in-10-year EECs for Currently Labeled Uses 

of Acifluorfen1

SWCC Scenario 

(standard unless 

noted)

Initial 

Application Date

Relative to 

Emergence

1-in-10 year peak 

daily, ppb

1-in-10 year, peak 

21-day average, 

ppb

1-in-10 year, peak 

60-day average, 

ppb

FL Strawberry -30 27.3 25.1 21.6

MS Soybean -15 14.2 13.7 12.7

NC Peanut -15 8.82 8.36 7.84

Rice from PFAM +15 2181 - - 1 In-the-paddy concentration

3.2.2.2 Aquatic Spray Drift Exposure to Acifluorfen

Spray drift exposure to aquatic organisms is also a potential exposure pathway. However, with 

edge of field deposition of acifluorfen from maximum application rates, even endangered species

LOCs are not exceeded for any aquatic taxa. Therefore, further analyses were not conducted.

3.2.3. Measures of Terrestrial Exposure

3.2.3.1. Terrestrial Wildlife

Exposure estimates for terrestrial organisms in the target area are derived using the T-REX 

model (version 1.5.2, 03/22/2012). This model incorporates the Kenaga nomograph, as modified 

by Fletcher et al. (1994), which is based on a large set of field residue data. The upper limit 

values from the nomograph represent the upper bound of residue values from actual field 

measurements (Hoerger and Kenaga 1972). The Fletcher et al. (1994) modifications to the 

Kenaga nomograph are based on measured field residues from 249 published research papers, 

including information on 118 species of plants, 121 pesticides, and 17 chemical classes. Based 

on these data, T-REX assumes a default 35-day foliar dissipation half-life in the absence of other 

chemical-specific data. 

3.2.3.2. Terrestrial Plants

Exposure of nontarget terrestrial and semi-aquatic (wetland) plant species is typically estimated 
24

using OPP’s TerrPlant (v1.2.2; USEPA, 2006b) model and is assumed to encompass areas 

outside the immediate use site. The TerrPlant model is used to derive EECs in runoff and drift

for terrestrial and semi-aquatic plants near areas where acifluorfen has been applied. Runoff 

exposure is assessed in TerrPlant in two scenarios: sheet and channel runoff. In the sheet runoff 

scenario, the treated area generating runoff is assumed to drain into an area with equal size 

containing seedlings, resulting in 1, 2, or 5% of the amount applied being deposited. In the 

channel runoff scenario, a ten-to-one ratio of treatment area to receiving area results in 10, 20, or 

50% of the amount applied being deposited on soil with emerging or emerged seedlings. Spray 

drift is also a source of pesticide loading to non-target areas. TerrPlant estimates EECs based on 

application rate, application method, chemical solubility in water, type of runoff and default 

assumptions of drift. Detailed information about TerrPlant, as well as the tool, can be found on 

the EPA’s website at http://www.epa.gov/pesticides/science/models_pg.htm#terrestrial.

The AgDRIFT (v2.01; May 2001) spray drift model is used to assess exposures of terrestrial 

plants to acifluorfen deposited on terrestrial or aquatic habitats by spray drift at a given distance 

from the application area. 

3.3. Ecological Effects Characterization 

In ecological risk assessments, effects characterization describes the types of effects a pesticide 

can have on aquatic and terrestrial organisms. To date, toxicity tests for amphibians or reptiles 

are not routinely required; birds are used as surrogates for reptiles and terrestrial-phase 

amphibians, and freshwater fish are used as surrogates for aquatic-phase amphibians. This 

characterization is based on the registrant-submitted toxicity data for birds, mammals, fish, 

invertebrates, and plants for acifluorfen.

As described in the Agency’s Overview Document (USEPA 2004), the most sensitive endpoint 

for each taxon is used for risk estimation. For this assessment, evaluated taxa include, freshwater 

fish (surrogate for aquatic-phase amphibians, freshwater invertebrates, aquatic plants, birds 

(surrogate for terrestrial-phase amphibians), mammals, terrestrial invertebrates, and terrestrial 

plants. 

Toxicity endpoints are established based on data generated from guideline studies submitted by 

the registrant, and from open literature studies that meet the criteria for inclusion into the 

ECOTOX database maintained by EPA/Office of Research and Development (ORD) (U.S. EPA, 

2004). Open literature data presented in this assessment were obtained from ECOTOX 

information obtained in July 2011. In order to be included in the ECOTOX database, papers 

must meet the following minimum criteria:

(1) the toxic effects are related to exposure from a single chemical;

(2) the toxic effects are on an aquatic or terrestrial plant or animal species;

(3) there is a biological effect on live, whole organisms;

(4) a concurrent environmental chemical concentration/dose or application rate is 

reported; and

(5) there is an explicit duration of exposure.

Data that pass the ECOTOX screen are evaluated along with the registrant-submitted data, and 
25

may be incorporated qualitatively or quantitatively into this assessment. In general, effects data 

in the open literature that indicate effects at lower concentrations than the registrant-submitted 

data are considered. The degree to which open literature data are quantitatively or qualitatively 

characterized is dependent on whether the information is relevant to the assessment endpoints 

(survival, reproduction, and growth) identified in Section 2.8. For example, endpoints such as 

behavior modifications are likely to be qualitatively evaluated, because quantitative relationships 

between modifications and reduction in species survival, reproduction, and/or growth are not 

available. 

In addition to registrant-submitted and open literature toxicity information, other sources of 

information, including use of the acute probit dose-response relationship to establish the 

probability of an individual effect and reviews of the Ecological Incident Information System 

(EIIS), are conducted to further refine the characterization of potential ecological effects 

associated with exposure to acifluorfen. A summary of the available aquatic and terrestrial 

ecotoxicity information, use of the probit dose-response relationship, and the incident 

information for acifluorfen are provided in Sections 4.1 through 4.4, respectively.

No toxicity data were available on specific acifluorfen mixtures with other pesticides; there is 

one registered multi a.i. product that includes both acifluorfen and sodium bentazon (PC Code 

103901).

3.3.1. Aquatic Toxicity Assessment

The most sensitive acute and chronic effects measurement endpoints associated with acifluorfen

exposure to freshwater and estuarine/marine species are summarized in Table 3.7. All 

acceptable and supplemental studies available for acifluorfen are described in the 2010 Problem 

Formulation (USEPA 2010b). However, data received after 2010 or that supersedes data 

reported therein are described below.

Results of acute toxicity studies in freshwater and estuarine/marine fish indicate that acifluorfen

is slightly-to-moderately toxic to aquatic invertebrates and fish on an acute exposure basis. 

Adult mortality was observed in the available fish early life stage (ELS) study. 
26

Table 3.7. Most Sensitive Acute and Chronic Toxicity Data for Aquatic Organisms 

Exposed to Acifluorfen 

Exposure 

Scenario Species

Affected 

Endpoint Toxicity Measurement

MRID

(Classification)

Freshwater Fish

Acute Rainbow trout 

(Oncorhynchus 

mykiss)

Mortality 96-hr LC50 = 17 mg a.i./L

Slope: N/A

00122752

(Acceptable)

Chronic Fathead minnow

(Pimephales 

promelas)

Mortality NOAEC = 1.0 mg a.i./L 48047402 

(Supplemental)

Freshwater Invertebrates

Acute Water flea

(Daphnia spp.)

Immobility 48 hr EC50 = 28.1 mg a.i./L

Slope: N/A

00071901

(Acceptable)

Chronic Water flea ACR NOAEC = 1.3 mg ai/L Calculated 

Estuarine/Marine Fish

Acute Sheepshead 

minnow

(Cyprinodon 

variegatus)

Mortality 96-hr LC50 = 39 mg total a.i./L

Slope: N/A

00122753

(Acceptable)

Chronic No studies available No Data

Estuarine/Marine Invertebrates

Acute Mysid shrimp 

(Americamysis 

bahia)

Mortality 96-hr LC50 = 3.8 mg a.i./L

Slope: NA

00122755

(Acceptable)

Chronic Mysid shrimp NOAEC= 0.17 mg ai/L 49305701

(Acceptable)

Aquatic Plants

14-day 

exposure

Duckweed

(Lemna gibba)

Frond count 14-day EC50 = 0.378 mg a.i./L

NOAEC = 0.180 mg a.i./L

41680702

120-hour 

exposure

Green algae

(Selenastrum 

capricornutum)

None NOAEC >0.265 mg a.i./L 41680702

96-hour 

exposure

Cyanobacteria 

(Anabaena flosaquae)

None 96-hr EC50 >0.355 mg a.i./L 41680702

3.3.1.1 Toxicity to Fish

Acute Effects

In a 96-h acute toxicity study, fathead minnow (Pimephales promelas) were exposed to 

acifluorfen at nominal concentrations of 0 (negative and solvent controls), 6.3, 13, 25, 50, and 

100 mg a.i./L under static-renewal (at 48 hours) conditions (MRID Number 48047401). Meanmeasured concentrations were <LOQ (0.33, controls), 4.9, 11, 20, 40, and 83 mg a.i./L. 

There were no mortality or sublethal effects noted in this study. The 96-h LC50 was >83 mg 

a.i./L. No mortality or sub-lethal effects were observed up to and including the highest 
27

concentration tested (83 mg a.i./L). This study is not used in RQ calculation because the 

previously available rainbow trout endpoint is more sensitive (see Table 3.7). 

Chronic Effects

The 32-day chronic toxicity of acifluorfen to the early life-stage of fathead minnow (Pimephales 

promelas) was studied under flow-through conditions (MRID 48047402). Fertilized 

eggs/embryos (l20/level, ca. 10 hours old) were exposed to nominal concentrations of 0 

(negative and solvent controls), 0.063, 0.13, 0.25, 0.50, and 1.0 mg a.i./L (adjusted for purity). 

Mean-measured concentrations were <0.0053 (LOQ, controls), 0.065, 0.13, 0.24, 0.53, and 1.0 

mg a.i./L, respectively. Since no treatment-related effects were indicated for any endpoint, the 

32-day NOAEC and LOAEC values were 1.0 and >1.0 mg a.i./L, respectively. However, time to 

hatch was not evaluated as a toxicological endpoint and the exposure range was quite low for a 

fish early life stage toxicity test, thus the study was classified as Supplemental. Nonetheless, this 

study provides a frank no-effect concentration that supersedes the non-definitive endpoint 

reported in the Problem Formulation.

3.3.1.2. Toxicity to Aquatic Invertebrates

Chronic Effects

The 28-day chronic toxicity of acifluorfen to mysids was studied under flow-through conditions

(MRID 48252402). Neonates less than 24 hours old were exposed to nominal concentrations of 

0 (negative control), 0.13, 0.25, 0.50, 1.0, and 2.0 mg a.i./L. Mean-measured concentrations 

were <0.0052 (LOQ, control), 0.14, 0.23, 0.52, 0.96, and 1.9 mg a.i./L, respectively. The 7-

through 28-day LC50 (for F0 survival) was >1.9 mg a.i./L. Since no treatment-related effects 

were indicated for any endpoint, the 28-day NOAEC and LOAEC values were 1.9 and >1.9 mg 

a.i./L, respectively. The study was classified as Supplemental because it was conducted below 

the limit of solubility and failed to establish a frank LOAEC. This study was conducted using 

lactofen as the test substance, and acifluorfen is a metabolite of lactofen. 

Subsequently, another 28-day chronic toxicity study with mysids (using a manufacturing use 

product (MUP) was submitted (MRID 49305701). The mean-measured concentrations in this 

study were <0.04 mg a.i./L (LOQ; control), 0.17, 0.318, 0.628, 1.22, 2.47 and 4.92 mg a.i./L. 

Although total young per female was significantly affected at 1.22 mg a.i./L, the NOAEC and 

LOAEC for the study were 0.170 mg a.i./L and 0.318 mg a.i./L based on F0 length at 28 days 

(male and female). This study is classified as Acceptable. The endpoints reported were 

corrected for purity.

As per the Problem Formulation, the NOAEC from the chronic mysid study is used to calculate 

an Acute-to-Chronic Ratio (ACR) for freshwater invertebrates (daphnids). The ACR is a simple 

ratio of the acute toxicity endpoint for mysids (LC50 = 3.8 mg a.i./L) over the mysid NOAEC 

(0.17 mg a.i./L). The resultant ratio (22) is applied to the LC50 for daphnids (28.1 mg a.i./L) to 

estimate a chronic NOAEC for daphnids, 1.3 mg a.i./L. 
28

3.3.2 Terrestrial Effects Characterization

The most sensitive acute and chronic effects measurement endpoints associated with acifluorfen 

exposure to terrestrial animals are summarized in Table 3.8. The most sensitive measurement 

endpoints for terrestrial plants are presented in Table 3.9. All acceptable and supplemental 

studies available for acifluorfen received prior to 2010 are described in the Problem Formulation 

(USEPA 2010b). Data received after 2010 or that supersedes data reported therein are described 

below.

Table 3.8. Acifluorfen Toxicity Measurement Endpoints Used in Risk Assessment for 

Terrestrial Animals.

Exposure 

Scenario

Species Exposure 

Duration

Toxicity Reference Value MRID 

(Classificationa)

Mammals

Acute

(Dose-based)

Laboratory rat 

(Rattus 

norvegicus)

Single oral dose LD50 = 1540 mg a.i./kg bw 00071887

Chronic

(Dietary-based)

Laboratory rat

(Rattus 

norvegicus)

Two-generation NOAEC = 400 mg a.i./kg-diet

LOAEC = 1800 mg a.i./kg-diet

00122743

Birds

Acute 

(Dose-based)

Bobwhite 

quail 

Colinus 

virginianus

14-day single 

oral dose

LD50 = 325 mg a.i./kg bw 00122747

Acute 

(Dietary-based)

Canary

Serinus 

canaria

8-day dietary LC50: >6530 mg a.i./kg diet 49213701 (Acceptable)

Chronic 

(Dietary-based)

Bobwhite 

quail 

C. virginianus

Avian 

reproduction 

study

NOAEC: 20 mg a.i./kg diet 

LOAEC: 100 mg a.i./kg diet

00107491

Terrestrial Invertebrates

Acute

(Contact)

Honeybee 48-hour LD50 >100 μg a.i./bee

NOAEC: 100 μg a.i./bee

46650202

(Acceptable)

a Where new data have been received.

Table 3.9. Acifluorfen Toxicity Measurement Endpoints for Terrestrial Plants.

Exposure 

Scenario

Taxon Toxicity Reference Value Reference

(Classification)a

Seedling 

Emergence

Grass (ryegrass) IC25 = in review

NOAEC = in review

MRID 41680701

(Acceptable)b

Non-grass

(cabbage)

IC25 = 0.032 lbs a.i./A 

NOAEC = 0.015 lbs a.i./A 

Vegetative Vigor Grass (corn) IC25 = 0.085 lbs a.i./A 

NOAEC = 0.068 lbs a.i./A 

MRIDs

46431401 
29

Exposure 

Scenario

Taxon Toxicity Reference Value Reference

(Classification)a

Non-grass (radish IC25 = 0.0038 lbs a.i./A 

NOAEC = 0.0009 lbs a.i./A

(Supplemental)

48612401

(Supplemental) a Where new data have been received or status has changed. b While the study was originally classified as Acceptable, a new review is now required.

3.3.2.1. Toxicity to Birds

The acute dietary toxicity of acifluorfen to young adult (11- to 16-month old) canary (Serinus 

canaria) was assessed over 8 days (MRID 49213701; Acceptable). Acifluorfen was 

administered to the birds in the diet at nominal concentrations of 0 (vehicle control), 400, 800, 

1600, 3200 and 6400 mg a.i./kg. Mean-measured concentrations were <60.0 (<LOD, control), 

386, 775, 1570, 3280, 6530 mg a.i./kg diet, respectively. No mortality was observed at any 

treatment level; thus, the 8-day dietary LC50 exceeded 6530 mg a.i./kg. There were reported 

effects on body weight and food consumption at the 6530 mg a.i./kg diet level, thus the 

observational NOAEC is 3208 mg a.i./kg-diet. Acifluorfen is classified as practically non-toxic 

to young adult canary (Serinus canaria).

3.3.2.3. Toxicity to Terrestrial Invertebrates

The acute contact toxicity of acifluorfen to the honey bee, Apis mellifera, was assessed in a 48-h 

study (MRID 47919601; Acceptable). Bees were exposed to acifluorfen at nominal

concentrations of 6.25, 12.5, 25.0, 50.0, and 100.0 μg a.i./bee. By 48 hours, there was 0% 

mortality in the negative control and 2% mortality in the solvent control. The 6.25, 12.5, 25.0, 

50.0, and 100 μg a.i./bee treatment groups had 0, 2, 3, 5, and 5% mortality, respectively. 

Sublethal effects were limited to one immobile bee in the 50.0 μg a.i./bee treatment group. The 

LD50 value was >100 μg a.i./bee and acifluorfen is classified as practically nontoxic to 

honeybees on an acute contact basis. However, there remain data gaps, based on the recent 

pollinator guidance.

3.3.2.4. Toxicity to Terrestrial Plants

The effect of acifluorfen on vegetative vigor was derived from two studies. The first study 

(MRID 46431401, Supplemental) did not achieve definitive endpoints for three species 

(cucumber, radish and tomato). A subsequent study (MRID 48612401; Supplemental) was 

submitted for radish and cucumber. While the first was considered ‘Invalid’ in 2005, that 

classification was due to the lack of definitive endpoints. The study was reconsidered for this 

assessment and, as noted above, is now considered ‘Supplemental’, as data for many of the 

species is sufficient for use in risk assessment. The second study addressed some, but not all, of 

the deficiencies in the first study. A no-effect value for tomato remains highly uncertain, 

although rerunning the statistics may allow for the derivation of an IC05 which could be used in 

an endangered species assessment. For the purposes of this assessment, the dataset is complete. 

The range of toxicity across all available species is reported in Table 3.10.
30

Table 3.10. Acifluorfen Vegetative Vigor Toxicity Endpoints for Terrestrial Plants (lbs 

a.i./A).

Crop Endpoint NOAEL IC25

Ryegrass None 0.017 >0.034

Corn Dry Weight 0.068 0.085

Onion Dry Weight 0.068 0.12

Wheat Plant height 0.0085 >0.14

Cucumber Dry Weight 0.0009 0.0042

Lettuce Dry Weight 0.0022 0.0095

Cabbage Plant Height 0.017 0.028

Radish Dry Weight 0.0009 0.0038

Soybean Dry Weight 0.034 0.087

Tomato Dry Weight <0.034* 0.046

* A no-effect value sufficient for risk assessment has not yet been determined

The effect of acifluorfen on the seedling emergence (MRID 41680701; Acceptable) of terrestrial 

plants is not completely reviewed. Although the study is considered ‘Acceptable’, the review (in 

1999) relies, for many endpoints, on visual phytotoxicity. This endpoint is no longer considered 

acceptable for use in risk assessment, and therefore data for four species in the study must be 

reanalyzed. However, the most sensitive species, cabbage (IC25=0.021; NOAEC=0.015), is used 

in Risk Estimation. Based on the data reported in the DER, grass species are considerably less 

sensitive to acifluorfen on a seedling emergence basis. 

3.4. ECOTOX Open Literature

A literature search in the Agency’s ECOTOX database (January 2015) resulted in 89 papers that 

passed the ECOTOX acceptability screen, all for plants. None of the papers could be directly 

related to FIFRA apical endpoints (IC25/EC25 for growth or survival) and thus are not included in 

this assessment. However, many of the studies report no-effect rates and these studies will be 

reviewed for the listed species effects determinations in a future endangered species risk

assessment.

4.0 Risk Characterization

4.1. Risk Estimation

Toxicity data and exposure estimates are used to evaluate the potential for adverse ecological 

effects on non-target species. This assessment for acifluorfen relies on the deterministic RQ 
31

method to provide a metric of potential risks. The RQ provides a comparison of exposure 

estimates to toxicity endpoints (i.e., the estimated exposure concentrations are divided by acute 

and chronic toxicity values). The resulting unitless RQs are compared to the Agency’s LOCs, as 

shown in Table 2.3. LOCs are used by the Agency to indicate when the use of a pesticide, as 

directed by the label, has the potential to cause adverse effects to non-target organisms.

4.1.1. Aquatic Organisms 

The highest screening-level aquatic EECs based on the maximum application rates for each use 

pattern were used to derive RQs. These exposure estimates represent concentrations in surface 

water (Table 3.7). Peak EECs are used to represent acute exposure to fish, aquatic invertebrates 

and aquatic plants, and the highest 21-day and 60-day average EECs represent chronic exposure 

to aquatic invertebrates and fish, respectively. EECs below represent parent acifluorfen only but 

inclusion of amino acifluorfen, the only major transformation product, as a toxic residue 

increases EECs by less than 10%. This was estimated by assuming stability to anaerobic aquatic 

metabolism, the only pathway by which amino acifluorfen formed as a major transformation 

product.

4.1.1.1. Fish and Invertebrates

Fish

Table 4.1 lists acute RQs calculated for fish (freshwater and estuarine/marine) and aquatic-phase 

amphibians exposed to acifluorfen, based on the peak EECs generated from SWCC modeling 

scenarios. Results of acute toxicity studies in freshwater and estuarine/marine fish (Table 3.13) 

indicate that acifluorfen is “highly toxic” to fish on an acute exposure basis. However, RQs for 

uses of acifluorfen fall below the Agency’s acute risk to listed species LOC (0.05), as well as the 

Agency’s acute risk to non-listed species LOC of 0.5. 

Table 4.1. Acute Risk Quotients for Fish and Aquatic-phase Amphibians Exposed to 

Acifluorfen at the Upper-bound EECs Using the Most Sensitive of the Available Endpoints.

SWCC Scenario (standard unless 

noted)

1-in-10 year peak daily, 

ppb

RQs

Freshwater

LC50 17 mg a.i./L 

Estuarine/Marine

LC50 39 mg a.i./L)

FL Strawberry 27.3 0.002 0.0007

MS Soybean 14.2 0.0008 0.0004

NC Peanut 8.82 0.0005 0.0002

Rice 218 0.013 0.006

1 Acute risk to non-listed species LOC for aquatic fish is 0.5 2 Acute risk to listed species LOC for aquatic fish is 0.05

As previously stated, LDPHs are a class of weed control chemicals that act in plants by 

inhibiting the enzyme protoporphyrinogen oxidase (protox), which is the last common enzyme in 

the heme and chlorophyll biosynthetic pathways. Several studies have documented enhanced 

toxicity of LDPHs to fish in the presence of uV light compared to toxicity observed under 
32

standard laboratory lighting. Given that aquatic organisms are likely to be exposed 

simultaneously to LDPH and uV light in natural settings, concerns have been raised that 

guideline chronic exposure laboratory tests may underestimate the toxicity of LDPH in the field

and so, the Agency is applying an interim adjustment factor of 29X to adjust no observed 

adverse effect concentration (NOAEC) values to account for the potential enhanced toxicity of 

LDPH chemicals under natural sunlight (USEPA 2010a). This enhanced sensitivity to LDPHs is 

not necessarily limited to fish and could be observed in other taxa such as aquatic invertebrates, 

birds, and mammals (Birchfield and Casida, 1997); however, the Agency is only applying an 

adjustment factor to fish at this time. 

Chronic exposure RQs for fish were calculated with both the endpoint derived from the guideline 

ELS study (standard laboratory lighting) and with the 29X adjustment factor applied (enhanced 

uV). RQs for fish that may not receive high-intensity uV light are below the Agency’s level of 

concern (1.0). RQs for fish with the LPDH adjustment factor exceed the LOC by up to 6-fold

(rice use; Table 4.2). The risk conclusions for fish also apply to amphibians in aquatic habitat. 

Although an acute toxicity study with the fathead minnow is available, it reports a non-definitive 

endpoint, therefore an ACR cannot be calculated and potential risk to estuarine/marine fish 

cannot be quantified. However, given that the acute endpoint for sheepshead minnow is greater 

than that for the rainbow trout, RQs for estuarine/marine fish would be lower than those for 

freshwater fish.

Table 4.2. Chronic Risk Quotients for Fish and Aquatic-phase Amphibians Exposed to 

Acifluorfen at the Upper-bound EECs Using the Most Sensitive of the Available Endpoints.

SWCC Scenario (standard unless

noted)

1-in-10 year 60d, 

ppb

RQs

Freshwater

NOAEC 1.0 mg a.i./L LDPH 29X factor

FL Strawberry 21.6 0.02 0.626

MS Soybean 12.7 0.01 0.368

NC Peanut 7.8 0.008 0.227

Rice 218 0.218 6.32

1 Chronic risk to listed and nonlisted LOC aquatic animals is 1.0. Bold indicates exceeds LOC

Aquatic Invertebrates

Based on the available acute studies, acifluorfen is categorized as practically nontoxic to 

Daphnia magna on an acute exposure basis. RQs for daphnids are <0.01 and do not exceed the 

acute risk LOC for either nonlisted (0.5) or listed (0.05) species. 

Mysids are more acutely sensitive to acifluorfen than daphnids, but RQs do not exceed the acute 

risk LOC for either nonlisted (0.5) or listed (0.05) species for most use patterns. The RQ for 

estuarine/marine invertebrates (0.057) marginally exceeds listed species LOC for the rice use

(Table 4.3). 
33

Table 4.3. Acute Risk Quotients for Aquatic Invertebrates Exposed to Acifluorfen at the 

Upper-bound EECs Using the Most Sensitive of the Available Endpoints.

SWCC Scenario (standard unless 

noted)

1-in-10 year peak daily, 

ppb

RQs

Freshwater

LC50 28.1 mg a.i./L 

Estuarine/Marine

LC50 3.8 mg a.i./L)

FL Strawberry 27.3 0.001 0.007

MS Soybean 14.2 0.0005 0.004

NC Peanut 8.82 0.0003 0.002

Rice 218 0.0077 0.057 1 Acute risk to non-listed species LOC for aquatic fish is 0.5 2 Acute risk to listed species LOC for aquatic fish is 0.05

There are no chronic LOC (1.0) exceedances for aquatic invertebrates except for the rice use. 

Most use patterns result in RQs an order of magnitude below the LOC, but the rice use results in 

an RQ of 1.3 for estuarine/marine invertebrates. 

4.1.1.2. Aquatic Plants

Although acifluorfen exhibits effects on the aquatic vascular plant (Lemna gibba), there is 

insufficient exposure for the LOC (1.0) to be exceeded for nonlisted vascular aquatic plants; the 

listed species RQ is 1.2, marginally exceeding the LOC. 

Similarly, aquatic nonvascular plants are affected by acifluorfen exposure. The most sensitive 

among the available taxa is the cyanobacteria, Anabaena flos-aquae. The nonlisted species LOC 

is not exceeded for this species, with the highest RQ = 0.8 (Table 4.4). The listed species RQ is 

not calculated as the endpoint used (NOAEC) is not reported in the Problem Formulation.

Table 4.4. Acute Risk Quotients for Aquatic Vascular and Nonvascular Plants Exposed to 

Acifluorfen at the Upper-bound EECs Using the Most Sensitive of the Available Endpoints.

SWCC Scenario (standard unless 

noted)

1-in-10 year peak daily, 

ppb

RQs

Vascular

IC50 0.378 mg a.i./L 

Nonvascular

IC50 >0.355 mg a.i./L)

FL Strawberry 27.3 0.07 <0.1

MS Soybean 14.2 0.04 <0.05

NC Peanut 8.82 0.02 <0.03

Rice 218 0.58 <0.82 1 Plant LOC is 1.0. Bold indicates exceeds LOC
34

4.1.2. Terrestrial Organisms 

4.1.2.1. Mammals

Although acifluorfen is classified as slightly toxic to mammals on an acute exposure basis, the 

EECs based on the labeled use patterns do not result in an exceedance of the acute risk LOC of 

0.5. The highest RQ (15g mammals feeding on short grass) is 0.04, a factor of 10 below the 

LOC.

Based on the currently labeled maximum application rates, there are chronic dose-based 

exposure concerns for mammals of all size classes for multiple use patterns RQs exceed the LOC 

by a factor of up to 3.4X for 15 g mammals foraging on short grass in the strawberry scenario, 

with exceedances at all size classes. Table 4.5 lists maximum chronic EECs and RQs for all of 

the currently labeled use rates based on the upper 90th percentile Kenaga values. The granivore 

forage class does not result in any exceedances for any of the use patterns and is not shown in the 

table. There are no exceedances of the LOC by dietary-based RQs, which are not adjusted for 

body weight.

Table 4.5. Chronic Dosed-based Mammalian RQs for the Uses of Acifluorfen. (Bold value 

indicate an exceedance of the LOC.)

Size 

Class

(g)

Short Grass Tall Grass Broadleaf 

Plants Fruits/Pods/Seeds Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

Strawberry 

(2@0.375 lbs 

a.i./A)

15d interval

15 149.56 3.40 68.55 1.56 84.13 1.91 9.35 0.21 58.58 1.33

35 103.37 2.91 47.38 1.33 58.14 1.63 6.46 0.18 40.49 1.14

1000 23.97 1.56 10.98 0.71 13.48 0.88 1.50 0.10 9.39 0.61

Soybean and 

peanut (0.5 lbs 

a.i./A

15 92.36 2.10 42.33 0.96 51.95 1.18 5.77 0.13 36.17 0.82

35 63.83 1.79 29.26 0.82 35.91 1.01 3.99 0.11 25.00 0.70

1000 14.80 0.96 6.78 0.44 8.32 0.54 0.92 0.06 5.80 0.38

Rice (0.25 lb 

a.i./A

15 57.21 1.30 26.22 0.60 32.18 0.73 3.58 0.08 22.41 0.51

35 39.54 1.11 18.12 0.51 22.24 0.63 2.47 0.07 15.49 0.44

1000 9.17 0.60 4.20 0.27 5.16 0.34 0.57 0.04 3.59 0.23
35

4.1.2.2. Birds

Acifluorfen exhibits greater toxicity to birds than to mammals, with an LD50 of 325 mg ai/kg-bw, 

classified as moderately toxic. At the currently registered label rates, acute dose-based RQs 

exceed the LOC (0.5 for nonlisted species) only for small (20 g) birds (and surrogates) foraging 

on short grass for the strawberry use (Table 4.6). There are no exceedances for the subacute 

dietary RQs for any size class/forage item combination. Exceedance of the listed species LOC 

are not indicated. 

Table 4.6. Acute Dose-based RQs for Birds (and Surrogates) for Acifluorfen. (Bold values 

indicate an exceedance of the listed LOC. )

Rate Size 

Class

(grams)

EECs and RQs

Short Grass

Tall Grass

Broadleaf 

Plants/

Small Insects

Fruits/Pods/

Seeds/

Large 

Insects

Arthropods

EEC RQ EEC RQ EEC RQ EEC RQ

Strawberry 

(2@0.375 lbs 

a.i./A)

15d interval

20 178.66 0.76 81.89 0.35 100.50 0.43 11.17 0.05 69.97 0.30

100 101.88 0.34 46.69 0.16 57.31 0.19 6.37 0.02 39.90 0.13

1000 45.61 0.11 20.91 0.05 25.66 0.06 2.85 0.01 17.86 0.04

Soybean and 

peanut

1@0.375 lbs 

a.i./A

1@0.125 lbs 

a.i./A

15d interval 

20 110.32 0.47 50.57 0.22 62.06 0.27 6.90 0.03 43.21 0.18

100 62.91 0.21 28.83 0.10 35.39 0.12 3.93 0.01 24.64 0.08

1000 28.17 0.07 12.91 0.03 15.84 0.04 1.76 0.00 11.03 0.03

Rice 0.25 lbs 

a.i./A

20 68.33 0.29 31.32 0.13 38.44 0.16 4.27 0.02 26.76 0.11

100 38.97 0.13 17.86 0.06 21.92 0.07 2.44 0.01 15.26 0.05

1000 17.45 0.04 8.00 0.02 9.81 0.02 1.09 0.00 6.83 0.02

There are chronic LOC exceedances for all use patterns for the short grass, tall grass and 

broadleaf plants and arthropods forage categories (Table 4.8). Chronic RQs exceed the LOC by 

up to 8-fold. There are no exceedances for the fruit/pods/seeds forage class.
36

Table 4.8. Chronic Dietary-based RQs for Birds (and Surrogates) for Acifluorfen. (Bold 

values indicate an exceedance of the LOC.)

EECs and RQs

Short Grass Tall Grass Broadleaf 

Plants

Fruits/Pods/

Seeds

Arthropods

Rate

(# apps; interval) EEC RQ EEC RQ EEC RQ EEC RQ EEC RQ

Strawberry 

2@0.375 lbs ai/A

15d interval 156.87 7.84 71.90 3.59 88.24 4.41 9.80 0.49 61.44 3.07

Soybean and 

peanut

1@0.375 lbs ai/A

1@0.125 lbs ai/A

15d interval

96.87 4.84 44.40 2.22 54.49 2.72 6.05 0.30 37.94 1.90

Rice

0.25 lbs ai/A 60.00 3.00 27.50 1.38 33.75 1.69 3.75 0.19 23.50 1.18

4.1.2.3. Terrestrial Invertebrates 

Acifluorfen is classified as practically nontoxic to honeybees on an acute exposure basis. Only a

non-definitive acute contact endpoint is available and, therefore RQs are not calculated. 

However, new data based on the recent pollinator guidance are expected at some point in the 

future and risk to terrestrial invertebrates will be revisited at that time.

4.1.2.4. Non-target Terrestrial Plants

Potential risk to terrestrial non-target vegetation are assessed by deriving RQs from terrestrial 

plant seedling emergence and vegetative vigor IC25 and NOAEC endpoints using TerrPlant. As 

expected with an herbicide, there are LOC exceedances for terrestrial plants. Because there are 

differences in the spray drift assumptions for aerial (5%) vs ground spray (1%) in TerrPlant, the

exposure estimates and subsequent RQs are dependent on application type. RQs are calculated 

based on the highest single application rate for each group of uses, and the higher application 

rates result in higher RQs and LOC exceedances. RQs are presented for ground application in 

Table 4.9 and for aerial application in Table 4.10. Because there currently is not a ‘grass’ 

endpoint for seedling emergence, the runoff RQs for this group are not calculated.
37

Table 4.9. Terrestrial Plant RQs for Ground Spray Applications of Acifluorfen. (Bold 

values indicate an LOC exceedance.)

Application 

Rate

lbs a.i./A Plant Type

Listed 

Status Dry Semi-Aquatic Spray Drift

0.75

Strawberry

Grass non-listed ND* ND <0.1

Grass listed ND ND 0.11

Non-grass non-listed 2.14 18.21 1.97

Non-grass listed 3.00 25.50 8.33

0.5

Soybean/Peanut

Grass non-listed ND ND <0.1

Grass listed ND ND <0.1

Non-grass non-listed 1.43 12.14 1.32

Non-grass listed 2.00 17.00 5.56

0.25

Rice

Grass non-listed ND ND <0.1

Grass listed ND ND <0.1

Non-grass non-listed 0.71 6.07 0.66

Non-grass listed 1.00 8.50 2.78

* Not determined

Table 4.10. Terrestrial Plant RQs for Aerial Spray Applications of Acifluorfen. (Bold 

values indicate an LOC exceedance.

Application 

Rate

lbs a.i./A Plant Type

Listed 

Status Dry Semi-Aquatic Spray Drift

0.75.

Strawberry

Grass non-listed ND* ND 0.44

Grass listed ND ND 0.55

Non-grass non-listed 3.57 19.64 9.87

Non-grass listed 5.00 27.50 41.67

0.5

Soybean/Peanut

Grass non-listed ND ND 0.29

Grass listed ND ND 0.37

Non-grass non-listed 2.38 13.10 6.58

Non-grass listed 3.33 18.33 27.78

0.25

Rice

Grass non-listed ND ND 0.15

Grass listed ND ND 0.18

Non-grass non-listed 1.19 6.55 3.29

Non-grass listed 1.67 9.17 13.89

* Not determined
38

4.1.2.5. Incident Database Review

A review of the Ecological Incident Information System (EIIS) database for incidents involving 

acifluorfen and the acifluorfen degradate was conducted on April 16, 2015. There is one 

reported incident (I003654-012; unlikely) for acifluorfen from Union County North Carolina 

from a registered use (as an active ingredient) on beans (likely soybeans). The incident reports 

mortality in an unknown number of unspecified fish species.

Similarly, a search of the Avian Incident Monitoring System (AIMS; 

http://www.abcbirds.org/abcprograms/policy/toxins/aims/aims/index.cfm) was conducted on 

April 16, 2015. AIMS is a database administered by the American Bird Conservancy that 

contains publicly available data on reported avian incidents involving pesticides. No incidents 

involving acifluorfen were found. 

Pesticide registrants report certain types of incidents to the Agency as aggregate counts of 

incidents occurring per product per quarter. Unless further information regarding this aggregate 

incident is received, it will be assumed that it resulted from registered use. There are 43 

aggregate plant incidents reported for acifluorfen between 1995 and 2003. 

4.2. Risk Description

The results of risk estimation indicate that registered uses of acifluorfen result in LOC 

exceedance for chronic risk to fish (and thus aquatic-phase amphibians) under enhanced uV 

conditions and to estuarine/marine invertebrates. The LOCs for acute risk to listed 

estuarine/marine invertebrates and for listed aquatic vascular plants are also exceeded. Acute 

risk to birds is indicated and chronic risk to both birds and mammals is indicated. Risk is not 

expected for terrestrial invertebrates, based on the available data. As expected with an herbicide, 

risk to nontarget terrestrial plants is indicated. There are exceedances of the acute LOC for listed 

birds in addition to the chronic risk.

4.2.1 Exposure to Aquatic Organisms

Surface water EECs resulting from applications of acifluorfen to soybean, peanut, strawberry, 

and rice are conservative estimates of exposure for the currently labeled uses of acifluorfen as a 

broadcast herbicide. Application practices were modeled assuming maximum application rates 

and minimum application intervals. Environmental fate inputs included 90 percent upper 

confidence limits on mean metabolism half-life estimates. Scenario selection focused on runoff 

prone soils that drain to a standard pond lacking an outlet. 

EECs from the rice use represent concentrations within rice paddies and undiluted effluent from 

the paddies. Rice paddies can serve as habitat to aquatic invertebrates, fish, and amphibians1

.

Exposure to aquatic organisms may also occur in receiving waters outside the rice paddy but 

would decrease as effluent residues are degraded and diluted. Additionally, only a single EEC is 

 1 http://www.fao.org/rice2004/en/f-sheet/factsheet7.pdf
39

used in risk estimation, analogous to the ‘peak’ from SWCC. Thus, no degradation is accounted 

for in modeling chronic EECs. 

Spray drift exposure to aquatic organisms is also a potential exposure pathway for acifluorfen. 

However, with edge of field deposition of acifluorfen from maximum application rates even 

endangered species LOCs are not exceeded for any aquatic taxa. 

4.2.2 Risks to Aquatic Animals

Based on the available data, risk to freshwater or estuarine/marine fish is not expected on an 

acute exposure basis. The highest RQ from all modeled use patterns is 0.012, below the listed 

species LOC of 0.05

Based on toxicity data from a study conducted under standard laboratory lighting, chronic risk to 

fish would not be expected, as the highest RQ would be 0.22, roughly one quarter of the LOC. 

When the interim adjustment factor of 29X is applied to the fish NOAEC from the guideline 

freshwater fish ELS study, RQs exceed the LOC by 6-fold for the rice use pattern; other use 

patterns do not indicate risk.

However, as discussed earlier, several studies have documented enhanced toxicity of LDPHs 

(such as acifluorfen) to fish in the presence of enhanced uV light compared to toxicity observed 

under standard laboratory lighting. Given that aquatic organisms are likely to be exposed 

simultaneously to LDPH and uV light in natural settings, concerns have been raised that standard 

laboratory tests may underestimate the toxicity of LDPHs in the field. This enhanced sensitivity 

to LDPHs may not be limited to fish and could be observed in other taxa such as aquatic 

invertebrates, birds, and mammals (Birchfield and Casida, 1997); however, the Agency is only 

applying an adjustment factor to fish at this time. Uncertainties regarding the EECs for rice are 

discussed above. 

As previously indicated, the 29X adjustment factor is considered an interim approach. In 2014, 

final study reports for the chemicals tested by the LDPH Task Force indicated that, depending on 

the chemical and endpoint, the factor of enhanced uV toxicity varied from approximately 1 to 

400x. EFED’s science policy panel looked at the available data and came to three conclusions:

1) High intensity uV exposure elicits a greater toxic response than standard light 

exposure for LDPH chemicals

2) The LDPH mechanism of action under high intensity uV is independent of the 

standard light toxicity mechanism of action

3) Since the standard light and high intensity uV studies demonstrate independent 

mechanisms of action, it is not appropriate to employ a factor to predict the uV

enhanced toxicity of an LDPH for which a standard light study is available

Accordingly, the panel recommended that to approximate the toxicity of LDPH chemicals under 

high intensity uV exposure conditions without additional research, the lowest molecular weight 

corrected NOAEC from high intensity uV testing (the molecular weight correction removes the 

variability introduced by active ingredient particle size for the purposes of toxicity comparison) 

can be used as a correction factor. This correction factor can be multiplied by the molecular 
40

weight of any LDPH chemical to generate a conservative estimate of toxicity under high 

intensity uV. However, in this assessment the 29X adjustment factor is still the vetted approach.

The exceedance of the LOC is based only on the freshwater ELS study. There are no chronic 

estuarine/marine fish data. However, based on the available acute toxicity studies, the

sheepshead minnow (surrogate for all estuarine/marine fish) is considerably less sensitive to 

acifluorfen exposure than the rainbow trout. While an ACR cannot be calculated because the 

acute value for sheepshead minnow is non-definitive, logically a chronic value calculated with a 

less sensitive acute endpoint would also be less sensitive (higher).

There are additional uncertainties regarding the chronic RQ exceedance. Not all fish and 

amphibians would be exposed to both acifluorfen and high uV light at the same time, but it has 

not yet been determined what factors might mitigate the effect. It would seem reasonable to 

assume that fish and amphibians inhabiting shallow, clear waterbodies would be more 

susceptible to chronic effects than those in deeper, more turbid and/or better-shaded waterbodies. 

Also, fish and amphibians inhabiting waterbodies at lower elevations or higher latitudes may also 

be less likely to exhibit chronic effects due to uV-enhanced toxicity. According to the Agency’s 

website http://www.epa.gov/sunwise/doc/uvradiation.html, other factors to consider regarding 

the amount of uV light are time of day, time of year, stratospheric ozone and weather (cloud 

cover). This risk assessment concludes that chronic exposure from the use of acifluorfen on rice 

may cause adverse effects to fish (and aquatic-phase amphibians) under enhanced uV conditions.

There are no exceedances for freshwater invertebrates based on the available data, with the 

highest RQ (for rice) being <0.01. There is a marginal LOC exceedance for acute effects to 

listed estuarine/marine invertebrates, with an RQ as high 0.06 based on the EEC for the rice use. 

No other use pattern results in any exceedance of the LOC. It is unclear how often the rice EEC 

is representative of estuarine/marine habitats.

There are no chronic data available for freshwater invertebrates, but the estuarine/marine acute 

endpoint is two orders of magnitude lower than the acute daphnid endpoint. While an ACR can 

be applied, it would result in RQs an order of magnitude lower than the mysid. Based on the 

mysid endpoint, there are no exceedances for chronic exposure except for the rice use pattern, 

with the highest RQ =1.3.

The lack of chronic exceedances for aquatic invertebrates is based on guideline data conducted 

with normal lighting. It is not clear whether invertebrates experience similar enhanced toxicity 

from acifluorfen exposure in the presence of high uV light as fish have been observed to. 

4.2.3 Risks to Aquatic Plants

Based on the available information for Lemna gibba, the uses of acifluorfen do not result in RQ 

exceedances of the LOC for aquatic vascular plants, with a maximum RQ (for aquatic 

nonvascular plants) of 0.58; there is a marginal exceedance of the LOC for listed aquatic 

vascular plants for the rice use with an RQ of 1.2. There are no exceedances for aquatic 

nonvascular plants based on the NOAEC, with the highest RQ being 0.82.
41

4.2.4. Risks to Mammals

As described above, acute RQs for mammals did not exceed any LOCs, including the listed 

species LOC. Based on the EEC values from T-REX and the highest dose tested in the acute rat 

study, the highest RQ for 15 gram mammals foraging on short grass, the most sensitive size class 

and forage item combination, is 0.05 for the strawberry use, which results in the highest exposure 

estimates for acifluorfen. 

When assessing potential chronic risk to mammals, the dietary-based NOAEC is converted to a 

dose-based NOAEL using body weight data from the laboratory toxicity study, which can be 

scaled to different mammalian size classes. The dose-based RQs are calculated using a body 

weight adjusted and consumption-weighted equivalent dose, as determined in the study. The 

adjustments account for the fact that smaller-sized animals have to consume more food in terms 

of their body weight than larger animals and that there is differential sensitivity to chemicals 

based on body size. By expressing the Kenaga nomogram-estimated residues in terms of daily 

equivalent dose, estimated environmental concentrations can then be compared to the dose-based 

NOAEL. For many applications, dose-based RQs exceed the LOC, with the strawberry use 

pattern resulting in the most exceedance (highest application rate) and rice resulting in the fewest 

(lowest application rate). The exceedances are as high 4X the LOC. Although not presented 

here, risk estimates using mean EECs result in fewer exceedance; however, mean EECs are 

expected to be exceeded roughly half of the time.

There are no exceedances for dietary-based based exposure but it should be noted that the dosebased approach assumes that the uptake and absorption kinetics of a gavage toxicity study 

approximate the absorption associated with uptake from a dietary matrix. Toxic response is a 

function of duration and intensity of exposure and the importance of absorption kinetics across 

the gut and the importance of enzymatic activation/deactivation of a toxicant may be important 

and are likely variable across chemicals and species. For many compounds a gavage dose

represents a very short-term high intensity exposure, where dietary exposure may be of a more 

prolonged nature. The dietary-based approach assumes that animals in the field are consuming 

food at a rate similar to that of confined laboratory animals. Energy content in food items differs 

between the field and the laboratory as does the energy requirements of wild and captive 

animals. This applies to birds as well as mammals.

4.2.5. Risk to Birds

The acute risk LOC for birds is indicated only for small (20g) birds foraging on short grass for 

the strawberry and soybean/peanut use patterns (although there are more listed species 

exceedances). Given that the RQs are for species foraging wholly on the treated area, it can be 

expected that risk-inducing exposure will attenuate quickly with distance from the field.

There are no exceedances based on the subacute dietary endpoint for birds, again suggesting that 

the dietary matrix may play a role in the toxicity of acifluorfen. But, as with mammals, the 

homogenous mixture fed in laboratory studies is not representative of field foraging conditions.
42

Chronic RQs exceed the LOC by up to 9-fold, and the exceedance are for all use patterns for 

birds foraging on short grass, tall grass broadleaf plants and arthropods. These risk estimates are 

generated using endpoints from studies where exposure was in the diet. Using mean EECs, the 

maximum RQs fall rough to one third of those derived from the upper-bound EECs, but the 

mean values are expected to be exceeded roughly half of the time.

Birds are generally used as surrogates for terrestrial-phase amphibians and reptiles. However, 

these taxa are poikilotherms (body temperature varies with environmental temperature) while 

birds are homeotherms (temperature is regulated, constant, and largely independent of 

environmental temperatures). Therefore, they tend to have much lower metabolic rates and 

lower caloric intake requirements than birds or mammals. As a consequence, birds are likely to 

consume more food than amphibians on a daily dietary intake basis, assuming similar caloric 

content of the food items. Therefore, use of an avian food intake allometric equation as a 

surrogate to reptiles and amphibians may result in an over-estimation of dietary exposure and 

risk for reptiles and terrestrial-phase amphibians. Conversely, other exposure routes (such as 

dermal and inhalation) may be relatively more important than dietary exposure in reptiles and 

particularly amphibians; these routes are not assessed in T-REX.

4.2.6. Potential Effects to Terrestrial Invertebrates

Given that data are available only for honeybees, this risk assessment makes the assumption that 

other insect taxa are similarly unaffected by acifluorfen exposure. However, this is a source of 

uncertainty for the assessment. 

Acifluorfen is classified as practically nontoxic to honeybees on an acute contact exposure basis, 

with LD50 >100 μg a.i./bee and virtually no sublethal effects observed. Therefore, RQs are not 

calculated and the potential for risk is believed to be low. It should be noted that the EPA is 

issuing data call-ins for multiple acute and chronic adult and larval honey bee studies across all 

registered pesticides for which exposure to bees is expected. Until those studies are submitted 

and reviewed, uncertainty regarding effects to bees will remain.

4.2.7. Risk to Terrestrial Non-target Plants

As expected with an herbicide, risk to nontarget plants is indicated. Based on the available data, 

grasses are less sensitive to acifluorfen than non-grasses, and generally vegetative vigor is a 

more sensitive life-stage than seedling emergence for acifluorfen. While vegetative vigor 

exposure is considered to be via spray drift, seedling emergence exposure is considered to be via 

either (or both) spray drift and run off. However, modeled runoff plus spray drift to semi-aquatic 

areas, which are compared to seedling emergence endpoints, results in the highest RQs. This 

scenario represents a 10 acre area running off into a one acre area. The RQs for nonlisted plants 

range up to over 19 (aerial application at the strawberry rate). As described above, frank 

seedling emergence endpoints for grasses are not currently defined so RQs are not determined; 

however, given that the data indicate that grasses are less sensitive than non-grasses, RQs would 

be lower. Spray drift RQs are determined using the more sensitive of the seedling emergence or 

vegetative vigor endpoints, so RQs are determined, ranging up to 10 (aerial application at the 
43

strawberry rate). The highest grass RQ is 0.55 for the same application. But lacking defined 

seedling emergence endpoints results in a large degree of uncertainty and care should be taken in 

interpreting this RQ.

There is not currently a vetted way to refine the risk posed by runoff, but to some degree, the 

exposure is reduced with distance from the application site. The TerrPlant assumptions for 

runoff, that sheet flow will result in a one-to-one area of exposure and that channelized runoff 

will result in a ten-to-one ratio of areas exposed do not take distance from application into 

consideration and assume equal deposition across the nontarget area. These assumptions also 

consider only solubility, while other chemical attributes, such as Koc, likely affect the amount of 

acifluorfen deposited on the nontarget areas.

Risk from drift alone can be refined using AgDRIFT. AgDRIFT was used to determine the 

distance from the edge of field where the nonlisted species RQ falls below the LOC for the 

species used in TerrPlant (Table 4.1) for both aerial and ground application for the labeled uses 

of acifluorfen. Model defaults for each scenario were used.

Table 4.1 Distance (feet) from the edge of field where the nonlisted species RQ falls below 

the terrestrial plant LOC for the most sensitive available endpoints.

Plant Species

Application 

rate Endpoint Ground Aerial

lbs a.i./A

IC25 Distance to LOC (in feet)

Grass (ryegrass) Strawberry

0.3751

0.0852 6.6 26

Non-grass 

(radish) 0.0038 95 >997

Grass (ryegrass) Soybean/peanut

0.375

0.0852 6.6 26

Non-grass 

(radish) 0.0038 95 >997

Grass (ryegrass) Rice

0.25

0.0852 3.3 10

Non-grass 

(radish) 0.0038 59 643

2

Assumed to be the lowest grass endpoint (vegetative vigor)

For acifluorfen, vegetative vigor appears to be a much more sensitive life stage than seedling 

emergence, thus greater impacts on this life stage may be expected to nontarget plants as well. 

Aerial applications result in considerably more drift than ground sprays, and so impacts from 

aerial applications are expected farther from the field edge for aerial applications. Application 

rate is a key variable in determining the distance effective drift is expected to travel, so 

applications of 0.375 lbs a.i./A will have an impact at greater distance from the application area 

than applications of 0.25 lbs a.i./A, if the same application method is used (e.g., aerial 

spray)(Table 4.1). Another key factor in drift distances is droplet size spectra. Coarser droplet 

sizes, as defined in the ASTM 572S standard or similar methods, would decrease the distance 

off-field beyond which effects from spray drift would not be expected. 
44

For grasses, most species are not expected to be at risk greater than 26 feet from the edge of the 

application area. However, risk to the most sensitive non-grass species are expected at >997 feet 

from the field edge at both the strawberry and soybean/peanut rates (0.375 lbs a.i./A) from aerial 

applications. For ground applications, risks are expected as far as 95 feet for species with 

sensitivities similar to radish. For acifluorfen, multiple applications are allowed. While the 

effect of multiple applications on the potential risk to plants is not currently quantified, it is 

reasonable to assume multiple applications would result in an increase in the risk estimates.

4.3. Additional Uncertainties and Data Gaps

4.3.1. Fate and Transport

With only one aerobic aquatic metabolism study and one anaerobic aquatic metabolism study 

available, a 3X adjustment is made to each half-life to conservatively account for the expected 

variability associated with those parameters. Additional data on varied aquatic systems are likely 

to reduce the associated input parameter, as the 90 percent upper confidence limit on the mean of 

the half-lives is employed as a standard model input, though it is possible that an individual 

observation can correspond with a longer half-life.

4.3.2. Effects 

While a 29X factor is being applied to account for the LPDH mode of action and its potential 

enhanced effect on fish from chronic exposure, there are no studies examining this effect on fish 

from acifluorfen. The degree to which the 29X factor over or under estimates the sensitivity of 

fish to acifluorfen is uncertain. It should be reiterated that use of the 29X factor is an interim 

approach, which may be subject to change as the results of a broader investigation into the 

LDPH effect are considered.

It is not clear from the available data whether the LPDH mode of action enhances toxicity to 

aquatic invertebrates (or terrestrial taxa) under high uV conditions. This assessment only applies 

an enhanced chronic toxicity factor for fish.

Based on available data mysids, an estuarine/marine aquatic invertebrate, are considerably more 

sensitive to acifluorfen than daphnids, a freshwater invertebrate. It is possible that some 

freshwater invertebrates are more sensitive than the tested daphnids. If there are freshwater 

invertebrates as sensitive to acifluorfen as mysids, this assessment may underestimate potential 

chronic effects to these taxa. 

5. Federally Threatened and Endangered (Listed) Species Concerns

In November 2013, the EPA, along with the U.S. Fish & Wildlife Service (USFWS), the 

National Marine Fisheries Service (NMFS) (collectively, the Services), and the U.S. Department 

of Agriculture (USDA) released a summary of their joint Interim Approaches for assessing risks 

to listed species from pesticides. The Interim Approaches were developed jointly by the 

agencies in response to the National Academy of Sciences’ (NAS) recommendations and reflect 
45

a common approach to risk assessment shared by the agencies as a way of addressing scientific 

differences between the EPA and the Services. The NAS report outlines recommendations on 

specific scientific and technical issues related to the development of pesticide risk assessments 

that EPA and the Services must conduct in connection with their obligations under the

Endangered Species Act (ESA) and FIFRA. 

The joint Interim Approaches were released prior to a stakeholder workshop held on November 

15, 2013. In addition, the EPA presented the joint Interim Approaches at the December 2013 

Pesticide Program Dialogue Committee (PPDC) and State-FIFRA Issues Research and 

Evaluation Group (SFIREG) meetings, and held a stakeholder workshop in April 2014, allowing 

additional opportunities for stakeholders to comment on the Interim Approaches. As part of a 

phased, iterative process for developing the Interim Approaches, the agencies will also consider 

public comments on the Interim Approaches in connection with the development of upcoming 

Registration Review decisions. The details of the joint Interim Approaches are contained in the 

white paper “Interim Approaches for National-Level Pesticide Endangered Species Act 

Assessments Based on the Recommendations of the National Academy of Sciences April 2013 

Report,” dated November 1, 2013. 

Given that the agencies are continuing to develop and work toward implementation of the 

Interim Approaches to assess the potential risks of pesticides to listed species and their 

designated critical habitat, this preliminary risk assessment for acifluorfen does not contain a 

complete ESA analysis that includes effects determinations for specific listed species or 

designated critical habitat. Although EPA has not yet completed effects determinations for 

specific species or habitats, for this preliminary assessment EPA conducted a brief screeninglevel assessment for all taxa of non-target wildlife and plants that assumes for the sake of the 

assessment that listed species and designated critical habitats may be present in the vicinity of 

the application of acifluorfen. This screening level assessment will allow EPA to focus its future 

evaluations on the types of species where the potential for effects exists once the scientific 

methods being developed by the agencies have been fully vetted. Once the agencies have fully 

developed and implemented the scientific methods necessary to complete risk assessments for 

endangered and threatened (listed) species and their designated critical habitats, these methods 

will be applied to subsequent analyses for acifluorfen as part of completing this registration 

review. 

6. Endocrine Disruptor Screening Program (EDSP)

Acifluorfen was not included in the first group of 67 chemicals issued an order to conduct Tier 1 

EDSP testing. For additional information on the EDSP, visit http://www.epa.gov/endo/.
46

6. References

Birchfield, N.B., and J.E. Casida. 1997. Protoporphyrinogen oxidase of mouse and maize: Target 

site selectivity and thiol effects on peroxidizing herbicide action. Pesticide Biochemistry 

and Physiology 57, 36-43.

USEPA 1998. Guidelines for Ecological Risk Assessment. EPA/630/R-95/002F. Published in 

63 FR 26846; May 14, 1998. U.S. Environmental Protection Agency, Washington, DC. 

April, 1998.

USEPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs, U.S. Environmental Protection Agency. Endangered and Threatened Species 

Effects Determinations. Office of Prevention, Pesticides and Toxic Substances, Office of 

Pesticide Programs, Washington, D.C. January 23, 2004. Online at: 

http://www.epa.gov/oppfead1/endanger/consultation/ecorisk-overview.pdf

USEPA. 2006a. Standardized Soil Mobility Classification Guidance. U.S. Environmental 

Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Office of 

Pesticide Programs, Environmental Fate and Effects Division, Memorandum. Apr. 21, 

2006.

USEPA. 2006b. User’s Guide: TerrPlant Version 1.2.2 (Terrestrial Residue Exposure model). 

United States Environmental Protection Agency. Environmental Fate and Effects 

Division. Office of Pesticide Programs. U.S. Environmental protection Agency. 

Washington, D.C. December 26, 2006.

USEPA. 2008. White Paper on Methods for Assessing Ecological Risks of Pesticides with 

Persistent, Bioaccumulative and Toxic Characteristics. Submitted to the FIFRA Scientific 

Advisory Panel. October 28-31, 2008. Office of Pesticide Programs, Environmental Fate 

and Effects Division, Washington, D.C.

USEPA. 2009. Guidance for Selecting Input Parameters in Modeling the Environmental Fate and 

Transport of Pesticides. U.S. Environmental Protection Agency, Office of Prevention, 

Pesticides and Toxic Substances, Office of Pesticide Programs, Environmental Fate and 

Effects Division, Oct. 22, 2009. Online at: 

http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm

USEPA. 2010a. Interim Guidance on Light-Dependent Peroxidizing Herbicides: Identification, 

DCI Justifcation, and Use of a Toxicity Adjustment Factor on Fish Chronic Endpoints, 

Memorandum from Don Brady to EFED Staff, August 2010. US Environmental 

Protection Agency, OCSPP, Office of Pesticide Programs. Office of Pesticide Programs, 

Environmental Fate and Effects Division, Washington, D.C.
47

USEPA. 2010b. Judkins, Donna and Stephanie Syslo. Registration Review – Preliminary 

Problem Formulation for the Ecological Risk and Drinking Water Exposure Assessments 

for Sodium Acifluorfen.

USEPA. 2015. Water Models. U.S. Environmental Protection Agency, Pesticides: Science and 

Policy, Models and Databases. Last updated April 29, 2015. Online at: 

http://www.epa.gov/oppefed1/models/water/

USDA. 2000. USDA Crop Profiles. Hosted by the Integrated Pest Management Centers. 

Available online at: http://www.ipmcenters.org/cropprofiles/index.cfm. 

Urban, D.J. and N.J. Cook, 1986. Hazard Evaluation Division Standard Evaluation Procedure 

Ecological Risk Assessment. EPA 540/9-85-001. U.S. Environmental Protection Agency, 

Office of Pesticide Programs, Washington D.C.

6.1 Submitted Product Chemistry and Environmental Fate Studies

114401 Acifluorfen acid Fate/Chemistry Bibliography MRID-Doc # Match

161-2 Photodegradation-water

MRID Citation Reference

42793502 2037659 in 

114402 

folders

Suter, P. (1993) Artificial Sunlight Photolysis of Acifluorfen in 

Aqueous Media at pH 7.0: Lab Project Number: 92176: M9311: 

93/5043. Unpublished study prepared by BASF Corp. in coop 

with BASF, Limburgerhof. 266 p. 

161-3 Photodegradation-soil

MRID Citation Reference

122759 See 

2037617 in 

114402

Gerecke, D.; Wargo, J. (1982) Photodegradation of Tackle (MC 

10109) on a Soil Surface: ASD Report No. 82/045. (Unpublished 

study received Dec 20, 1982 under 359-708; submitted by 

Rhone-Poulenc, Inc., Monmouth Junction, NJ; CDL:071323-D) 

162-1 Aerobic soil metabolism

MRID Citation Reference

122761 also 

listed as 

137754 in PC 

Code 114402

2037619 in 

114402

Piznik, M.; Wargo, J. (1982) Abbreviated Aerobic/Anaerobic 

Soil Metabolism Study with Radiolabelled Tackle (MC-10978): 

ASD No. 82/047. (Unpublished study received Dec 20, 1982 

under 359-708; submitted by Rhone-Poulenc, Inc., Monmouth 

Junction, NJ; CDL:071324-B) 
48

71593 also 

listed in PC 

Code 114402

DER not 

located

Ku, C.C.; Norris, F.A.; Miller, K.M.; et al. (1980?) Metabolism 

of Carbon-14 Labelled MC 10978 in Georgia and New Jersey 

Soils un- der Aerobic and Anaerobic Laboratory Conditions: 

Progress Memo- randum PME-80.52. (Unpublished study 

received Jan 5, 1981 under 2224-EX-18; submitted by Mobil 

Chemical Co., Industrial Chemi- cals Div., Richmond, Va.; 

CDL:244155-D) 

163-1 Leach/adsorp/desorption

MRID Citation Reference

42075601 DER not 

locatedcheck 

contract 

DERS

Wing, C. (1987) Determination of Adsorption/Desorption 

Constants of Acifluorfen: Lab Project Number: 12100: 88/5008. 

Unpublished study prepared by Cambridge Analytical 

Associates, Inc. 34 p. 

42793501 2037650 in 

PC Code 

114402

Suter, P. (1993) Adsorption and Desorption of Acifluorfen on 

Representative Agricultural Soils: Lab Project Number: 92177: 

M9312: 93/5042. Unpublished study prepared by BASF Corp. in 

coop with Agvise Labs and BASF, Limburgerhof. 109 p. 

45686503 Open lit Gennari, M.; Negre, M.; Raimondo, E. (1994) Effect of Soil 

Properties on Adsorption and Desorption of Acifluorfen. Journal 

of Agricultural Food Chemistry 42:2329-2332. 

114402 Acifluorfen Na Salt Fate/Chemistry Bibliography MRID-Doc#

Fate Studies= Folder F000648

161-1 Hydrolysis

MRID Citation Reference

71584 2037615 or 

2037634

Norris, F.A.; Hassell, A.E. (1980) Hydrolytic Stability of MC10978 in Buffered Aqueous Solutions: Technical Memorandum 

TME-80.17. (Unpublished study received Jan 5, 1981 under 

2224-EX-18; sub- mitted by Mobil Chemical Co., Industrial 

Chemicals Div., Rich- mond, Calif.; CDL:244157-B) 

80127 DER not 

located

Hofmann, C.K. (1979) Hydrolysis Study of RH-8817: TR 34H79-15. (Unpublished study received Aug 6, 1981 under 707-EX98; sub- mitted by Rohm & Haas Co., Philadelphia, Pa.; 

CDL:070260-E) 

122757 2037615 Norris, F.; Hassell, A. (1980) Hydrolytic Stability of MC-10978 

in Buffered Aqueous Solutions: Technical Memorandum TME80.17. (Unpublished study received Dec 20, 1982 under 359-

708; prepared by Mobil Chemical Co., submitted by Rhone-
49

Poulenc, Inc., Mon- mouth Junction, NJ; CDL:071323-B) 

ACC 95735 2068708 Augenstein, L 1975 Hydrolysis study not found in OPPIN

92168032 Registrant 

summary

Keene, E. (1990) BASF Corporation Phase 3 Summary of MRID 

00107479. A Hydrolysis Study with Carbon 14-RH-6201: 

Technical Report No. 3423-75-66; 90/6151. Prepared by Rohm 

and Haas Company. 19 p. 

161-2 Photodegradation-water

MRID Citation Reference

41891208 2037646 Panek, M. (1991) Aqueous Photolysis of ?carbon 14|-Sodium 

Acifluor- fen: Lab Project Number: M9024: M9118. 

Unpublished study pre- pared by BASF Corp. 86 p. 

42793502 2037649 Suter, P. (1993) Artificial Sunlight Photolysis of Acifluorfen in 

Aqueous Media at pH 7.0: Lab Project Number: 92176: 

M9311: 93/5043. Unpublished study prepared by BASF Corp. 

in coop with BASF, Limburgerhof. 266 p. 

44195001 Supplemental 

to 41891208

Panek, M. (1993) Aqueous Photolysis of (carbon 14)-Sodium 

Acifluorfen: Supplemental Report to MRID 41891208: Lab 

Project Number: 93/5220: M9024: M9314. Unpublished study 

prepared by BASF Corp. 49 p. 

44195002 Referenced 

DER not 

located

Venkatesh, K. (1996) Further Characterization of Photolytic 

Degradation Products from the (carbon 14)-Acifluorfen (NO2 

Label) Artificial Sunlight Photolysis: Lab Project Number: 

96/5112: 95037: M9610. Unpublished study prepared by BASF 

Corp. 110 p. 

71585 2037625 Norris, F.A.; Ku, C.C.; Hassell, A.E. (1980) Photodegradation 

of MC-10978 in Aqueous Solution: Progress Memorandum 

PME-80.50. (Unpublished study received Jan 5, 1981 under 

2224-EX-18; sub- mitted by Mobil Chemical Co., Industrial 

Chemicals Div., Rich- mond, Va.; CDL:244157-C) 

122758 2037616 and 

2037636

Somma, N. (1982) Photodegradation of Tackle in Aqueous 

Solution: ASD No. 82/048. (Unpublished study received Dec 

20, 1982 under 359-708; submitted by Rhone-Poulenc, Inc., 

Monmouth Junction, NJ; CDL:071323-C) 

137750 Response to 

review above

Somma, N. (1983?) Tackle Herbicide: Reply to Environmental 

Fate Re- views for Somma, N.; F. A. Norris and A. Guardigli--

September, 1983--Photodegradation of Tackle in Aqueous 

Solution, Rhone-Pou- lenc, Inc., Monmouth Junction, NJ, ASD 

Report No.: 82/048, Acc. No. 071323: Ref. 83/BHL/857/AG. 

(Unpublished study re- ceived Mar 19, 1984 under 359-708; 
50

submitted by Rhone-Poulenc, Inc., Monmouth Junction, NJ; 

CDL:252764-B) 

ACC 95735 2068708 pg 5 Augenstein, 1979 Photolysis in Water

161-3 Photodegradation-soil

MRID Citation Reference

71592 DER not 

located

Ku, C.C.; Norris, F.A.; Sayles, B.A. (1980?) Photodegradation 

of MC 10978 on Soil Thin Layer Plates: Progress Memorandum 

PME-80.54. (Unpublished study received Jan 5, 1981 under 

2224-EX-18; sub- mitted by Mobil Chemical Co., Industrial 

Chemicals Div., Rich- mond, Va.; CDL:244155-C) 

107501 2068708 pg 

10 

2,4-D and 

Aciflourfen

Peirson, W.; Fisher, J. (1978) Long Term Laboratory Photolysis 

Study of RH-6201 on Soil: TR 34H-78-8. (Unpublished study received Dec 14, 1978 under 707-149; submitted by Rohm & Haas 

Co., Philadelphia, PA; CDL:097720-C) 

44412901 Only 

referenced 

DER not 

located

Venkatesh, K.; Oakley, W. (1997) Photolysis of (carbon 14)-

Acifluorfen (nitrogen dioxide and carbon trifluoride) on Soil: 

Lab Project Number: 96143: 97/5057. Unpublished study 

prepared by BASF Corp. and Agvise Labs. 137 p. 

122759

may be for 

114401

2037617 Gerecke, D.; Wargo, J. (1982) Photodegradation of Tackle (MC 

10109) on a Soil Surface: ASD Report No. 82/045. (Unpublished 

study received Dec 20, 1982 under 359-708; submitted by 

Rhone-Poulenc, Inc., Monmouth Junction, NJ; CDL:071323-D)

41688501 2037647 Looper, G. (1990) Acifluorfen: Photodegradation on Soil: 

?Phase 3 Summary|: Lab Project Number: ASD 82/045. 

Unpublished study prepared by Rhone-Poulenc, Inc. 22 p.

107501 DER not 

located

Peirson, W.; Fisher, J. (1978) Long Term Laboratory Photolysis 

Study of RH-6201 on Soil: TR 34H-78-8. (Unpublished study received Dec 14, 1978 under 707-149; submitted by Rohm & Haas 

Co., Philadelphia, PA; CDL:097720-C) 

162-1 Aerobic soil metabolism

MRID Citation Reference

122760 2037618 Wargo, J.; Ku, C.; Norris, F.; et al. (1982) Metabolism of 

Carbon- 14 Labelled MC-10978 in Kansas, Virginia, Georgia 

and New Jersey Soils under Aerobic and Anaerobic Conditions: 

ASD No. 82/040. (Unpublished study received Dec 20, 1982 

under 359-708; submit- ted by Rhone-Poulenc, Inc., Monmouth 

Junction, NJ; CDL:071324-A) 
51

137751 See 122760 

above

Wargo, J. (1983?) Metabolism of Carbon-14 Labelled MC10978 in Kan- sas, Virginia, Georgia and New Jersey Soils under 

Aerobic and Anaerobic Conditions (ASD No. 82/040): 

?Response to Review|. (Unpublished study received Mar 19, 

1984 under 359-708; submit- ted by Rhone-Poulenc, Inc., 

Monmouth Junction, NJ; CDL:252764-C) 

143572 2037637 pg 

12 in pdf

Gemma, A.; Wargo, J. (1984) Metabolism of [Carbon-14]-MC10978 (Tackle) in Soil under Aerobic and Anaerobic Conditions: 

Report No. 84/088. Unpublished study prepared by RhonePoulenc Inc. 144 p. 

147720 2037637 pg 

20 in pdf

Norris, F.; Wargo, J.; Jordan, E.; et al. (1984) Mobility and 

Dissipation Rates of Tackle Herbicides as Determined from 

Field Experiments: ASD No. 84/099. Unpublished study 

prepared by Rhone-Poulenc Inc. 44 p. 

71593 Progress 

report 

DER not 

located

Ku, C.C.; Norris, F.A.; Miller, K.M.; et al. (1980?) Metabolism 

of Carbon-14 Labelled MC 10978 in Georgia and New Jersey 

Soils un- der Aerobic and Anaerobic Laboratory Conditions: 

Progress Memo- randum PME-80.52. (Unpublished study 

received Jan 5, 1981 under 2224-EX-18; submitted by Mobil 

Chemical Co., Industrial Chemi- cals Div., Richmond, Va.; 

CDL:244155-D) 

137754 2037619 Piznik, M.; Wargo, J. (1983?) Abbreviated Aerobic/Anaerobic 

Soil Metabolism with 14C-Tackle (MC-10978): ASD No. 

82/047: ?Response to Review|. (Unpublished study received Mar 

19, 1984 under 359- 708; submitted by Rhone-Poulenc, Inc., 

Monmouth Junction, NJ; CDL:252764-F) 

137755 2037620 Gemma, A.; Wargo, J. (1982?) The Metabolism and Fate of 

14C-MC- 10978 in New Jersey Soil (ASD No. 82/051): 

?Response to Review|. (Unpublished study received Mar 19, 

1984 under 359-708; submit- ted by Rhone-Poulenc, Inc., 

Monmouth Junction, NJ; CDL:252764-G) 

122763

Acc 71324

2037621 Gemma, A.; Wargo, J. (1982) Tackle Soil Metabolism: 

Metabolic Fate of 14C-MC-10978 in Maryland Silt Loam Soil: 

ASD No. 82/053. (Unpublished study received Dec 20, 1982 

under 359-708; submit- ted by Rhone-Poulenc, Inc., Monmouth 

Junction, NJ; CDL:071324-D)

122762 Gemma, A.; Wargo, J. (1982) The Metabolic Fate of 14C-MC10978 in New Jersey Loamy Sand Soil: ASD No. 82/051. 

(Unpublished study received Dec 20, 1982 under 359-708; 

submitted by Rhone-Poulenc, Inc., Monmouth Junction, NJ; 

CDL:071324-C)

ACC 95733 2068708 pg Fisher, 1976 Lab Soil Metabolism study
52

19

32853 2037613 Rohm and Haas Company (1980) Blazer^(TM)I 2L Herbicide 

(707-149); Blazer^(TM)I 2S Herbicide (707-150): 

Environmental Chemistry Data--Supplement to Registration File. 

(Unpublished study re- ceived May 2, 1980 under 707-149; 

CDL:242395-A)

122763 2037634 pg 

18 of pdf

Gemma, A.; Wargo, J. (1982) Tackle Soil Metabolism: 

Metabolic Fate of 14C-MC-10978 in Maryland Silt Loam Soil: 

ASD No. 82/053. (Unpublished study received Dec 20, 1982 

under 359-708; submit- ted by Rhone-Poulenc, Inc., Monmouth 

Junction, NJ; CDL:071324-D) 

162-2 Anaerobic soil metabolism

MRID Citation Reference

143572 2037637 pg 

12 in pdf

Gemma, A.; Wargo, J. (1984) Metabolism of [Carbon-14]-MC10978 (Tackle) in Soil under Aerobic and Anaerobic Conditions: 

Report No. 84/088. Unpublished study prepared by RhonePoulenc Inc. 144 p. 

71593 See above 

in aerobic

Ku, C.C.; Norris, F.A.; Miller, K.M.; et al. (1980?) Metabolism 

of Carbon-14 Labelled MC 10978 in Georgia and New Jersey 

Soils un- der Aerobic and Anaerobic Laboratory Conditions: 

Progress Memo- randum PME-80.52. (Unpublished study 

received Jan 5, 1981 under 2224-EX-18; submitted by Mobil 

Chemical Co., Industrial Chemi- cals Div., Richmond, Va.; 

CDL:244155-D) 

137754 2037619 Piznik, M.; Wargo, J. (1983?) Abbreviated Aerobic/Anaerobic 

Soil Metabolism with 14C-Tackle (MC-10978): ASD No. 

82/047: ?Response to Review|. (Unpublished study received Mar 

19, 1984 under 359- 708; submitted by Rhone-Poulenc, Inc., 

Monmouth Junction, NJ; CDL:252764-F)

76706 2068806 pg 

2 of pdf or 

2037551

Rogerson, T.D.; Hawke, J.A. (1981) Aerobic Aquatic 

Metabolism of ^14IC-labeled RH-6201 (Blazer): Technical 

Report No. 36H-81-6. (Unpublished study received May 27, 

1981 under 707-149; submit- ted by Rohm & Haas Co., 

Philadelphia, Pa.; CDL:070115-F) 

162-3 Anaerobic aquatic metab.

MRID Citation Reference

42330603 DER not Panek, M. (1992) Carbon 14-Sodium Acifluorfen Anaerobic 
53

located see 

study below

Aquatic Metabolism Study: Status Report: Lab Project Number: 

92/5073. Unpublished study prepared by BASF Corp. 18 p. 

43155201 2068709 Panek, M.; Reese, C. (1994) Anaerobic Aquatic Metabolism of 

(carbon 14) Sodium Acifluorfen: Lab Project Number: 92062: 

M9326. Unpublished study prepared by BASF Corp. and 

Agvise, Inc. 108 p. 

162-4 Aerobic aquatic metab.

MRID Citation Reference

42330601 2037648 Panek, M. (1992) Aerobic Aquatic Metabolism of ?carbon 14|-

Sodium Aciluorfen: Lab Project Number: 91056: M9204. 

Unpublished study prepared by BASF Corp. 77 p. 

107503 2068708 Caplan, J.; Schroader, K. (1978) 14C-RH-6201 Activated Sludge 

Metabolism: Laboratory No. 7PL-1-1. (Unpublished study 

received Dec 14, 1978 under 707-149; prepared by Biospherics, 

Inc., submitted by Rohm & Haas Co., Philadelphia, PA; 

CDL:097720-E) 

163-1 Leach/adsorp/desorption

MRID Citation Reference

71591 2037622 or 

2037634 pg 

18

Norris, F.A.; Miller, K.M. (1978?) Mobility of MC 10978 in 

Four Soil Types: Technical Memorandum TME-80.24. 

(Unpublished study received Jan 5, 1981 under 2224-EX-18; 

submitted by Mobil Chemi- cal Co., Industrial Chemicals Div., 

Richmond, Va.; CDL:244155-B) 

107496 2068708 pg 

43 or pg 29 

in PDF

Fisher, J. (1978) Leaching and Mobility Studies in Soil Treated 

with RH-6201: TR 34H-78-10. (Unpublished study received Dec 

14, 1978 under 707-149; submitted by Rohm & Haas Co., 

Philadelphia, PA; CDL:097719-A) 

ACC 95733 2068708 pg 

32 in PDF

Fisher, 1976 Leaching study in soil in compilation below –

Rohm & Haas Co. (1976) ?Analyses for Residues of RH-6201 

and Other Products in Crops, Soil, and Animals|. (Compilation; 

unpub- lished study received Jan 17, 1977 under 707-EX-87; 

CDL:095734- A; 095733; 095735)

107496 2068708 pg 

32 in PDF

Fisher, J. (1978) Leaching and Mobility Studies in Soil Treated 

with RH-6201: TR 34H-78-10. (Unpublished study received Dec 

14, 1978 under 707-149; submitted by Rohm & Haas Co., 

Philadelphia, PA; CDL:097719-A)
54

107497 2068708 pg 

34 in PDF

Garstka, T. (1978) The Adsorptive and Desorptive Behavior of 

RH- 6201 on Drummer Silt Loam Soil: TR 34H-78-4. 

(Unpublished study received Dec 14, 1978 under 707-149; 

submitted by Rohm & Haas Co., Philadelphia, PA; 

CDL:097719-B) 

122766 2037624 Norris, F.; Ku, C. (1981) Field Dissipation and Leaching 

Studies: Progress Memorandum PME-81.48. (Unpublished study 

received Dec 20, 1982 under 359-708; prepared by Mobil 

Chemical Co., submitted by Rhone-Poulenc, Inc., Monmouth 

Junction, NJ; CDL: 071325-C) 

122764 See same 

citation 

71591

Norris, F.; Miller, K. (1980) Mobility of MC 10978 in Four Soil 

Types: Technical Memorandum TME-80.24. (Unpublished study 

re- ceived Dec 20, 1982 under 359-708; prepared by Mobil 

Chemical Co., submitted by Rhone-Poulenc, Inc., Monmouth 

Junction, NJ; CDL:071325-A) 

122765 2037623

Or 2037634 

pg 19 in pdf

Norris, F. (1982) Adsorption/Desorption of Acifluorfen Sodium 

(LS-80-1213, MC-10978) from a Silt Loam Soil: PDD No. 

82/030. (Unpublished study received Dec 20, 1982 under 359-

708; submit- ted by Rhone-Poulenc, Inc., Monmouth Junction, 

NJ; CDL:071325-B) 

42793501 2037650 Suter, P. (1993) Adsorption and Desorption of Acifluorfen on 

Representative Agricultural Soils: Lab Project Number: 92177: 

M9312: 93/5042. Unpublished study prepared by BASF Corp. in 

coop with Agvise Labs and BASF, Limburgerhof. 109 p. 

44412902 2010545

2068710-

not signed

Mills, C.; Goetz, A. (1997) Adsorption/Desorption of (carbon 

14) BH 9048-A (Amino Acifluorfen) on Soil: Lab Project 

Number: 96161: 97/5334. Unpublished study prepared by BASF 

Corp. 61 p. 

92168033 Registrant 

summary

Keene, E. (1990) BASF Corporation Phase 3 Summary of MRID 

00071591. Mobility of MC 10978 in Four Soil Types: Technical 

Memorandum TME-80.24; 90/6150. Prepared by Mobil 

Chemical Company. 16 p. 

163-3 Volatility - field

MRID Citation Reference

147720 2037637 pg 

20 of pdf

Norris, F.; Wargo, J.; Jordan, E.; et al. (1984) Mobility and 

Dissipation Rates of Tackle Herbicides as Determined from 

Field Experiments: ASD No. 84/099. Unpublished study 

prepared by Rhone-Poulenc Inc. 44 p. 

164-1 Terrestrial field dissipation
55

MRID Citation Reference

94999 DER not 

located

Cubbedge, S.D. (1980) Analysis for Residues of Mobil 10978 in 

Soil: Laboratory Nos. 80-2680-3-3 and 80-2865-3-1. Includes 

Mobil Chemical Method 157-80 dated Nov 6, 1980. 

(Unpublished study, including letters dated Jan 2, 1981 from G. 

Milad to Arleigh Hartkopf and Jan 5, 1981 from S.D. Cubbedge 

to Arleigh Hartkopf, received Feb 6, 1981 under 2224-EX-18; 

prepared by Biospherics, Inc., submitted by Mobil Chemical Co., 

Industrial Chemicals Div., Richmond, Va.; CDL:244384-E) 

107498 2068708 pg 

38 in PDF

Rogerson, T.; Zogorski, W.; Bradley, G.; et al. (1978) A Residue 

Decline Study of Soil Treated with 14C-RH-6201 at Newton, 

Pa., in 1977: TR 344-78-19. (Unpublished study received Dec 

14, 1978 under 707-149; submitted by Rohm & Haas Co., 

Philadelphia, PA; CDL:097719-C) 

107499 DER not 

located

Rohm & Haas Co. (1978) Soil Detailed Analytical Reports: 

?Blazer 2L Herbicide (Formerly RH-6201); Blazer 2S 

Herbicide|. (Compi- lation; unpublished study received Dec 14, 

1978 under 707-149; CDL:097719-D) 

122722 DER not 

located

Rhone-Poulenc, Inc. (1982) Tackle Herbicide: Residue 

Chemistry Pro- file: ASD No. 821054. (Compilation; 

unpublished study received Dec 20, 1982 under 359-708; 

CDL:071305-A; 071307) 

122762 2037636 pg 

8 of pdf

Gemma, A.; Wargo, J. (1982) The Metabolic Fate of 14C-MC10978 in New Jersey Loamy Sand Soil: ASD No. 82/051. 

(Unpublished study received Dec 20, 1982 under 359-708; 

submitted by Rhone-Poulenc, Inc., Monmouth Junction, NJ; 

CDL:071324-C) 

122766 2037624 Norris, F.; Ku, C. (1981) Field Dissipation and Leaching 

Studies: Progress Memorandum PME-81.48. (Unpublished study 

received Dec 20, 1982 under 359-708; prepared by Mobil 

Chemical Co., submitted by Rhone-Poulenc, Inc., Monmouth 

Junction, NJ; CDL: 071325-C) 

137136 DER not 

located

Norris, F.; Ku, C. (1981) Field Dissipation and Leaching of 

Tackle Herbicide in Four Soil Types: Project No. 15118. 

(Unpublished study received Jan 11, 1984 under 359-708; 

prepared by Mobil Chemical Co., submitted by Rhone-Poulenc, 

Inc., Monmouth Junc- tion, NJ; CDL:252141-B) 

137756 2037636 pg 

10 of pdf

Guyton, C.; Perez, G.; Berner, R.; et al. (1983) Soil Dissipation 

Data on Tackle under Field Conditions: 1982 Field Programs F-7 

& F-10: ASD Report No. 83/025. (Unpublished study received 
56

Mar 19, 1984 under 359-708; submitted by Rhone-Poulenc, Inc., 

Mon- mouth Junction, NJ; CDL:252764-H) 

143573 addendum Guyton, C. (1984) Addendum to Report: Soil Dissipation Data 

on Tac- kle under Field Conditions: 1982 Field Programs F-7 & 

F-10: ASD No. 84/100. Unpublished study prepared by RhonePoulenc, Inc. 21 p. 

147720 2037637 pg 

20 in pdf

Norris, F.; Wargo, J.; Jordan, E.; et al. (1984) Mobility and 

Dissipation Rates of Tackle Herbicides as Determined from 

Field Experiments: ASD No. 84/099. Unpublished study 

prepared by Rhone-Poulenc Inc. 44 p. 

41172801 2037576 Norris, F. (1989) A Small Scale Prospective Field Dissipation 

and Groundwater Monitoring Study with Acifluorfen-Sodium, 

the Active Ingredient of Tackle Brand Herbicide and Blazer 

Brand Herbicide: Project ID: File No. 40576; Protocol No. MEF87-010. Unpublish- ed study prepared by Rhone-Poulenc Ag Co. 

813 p. 

41833201 

MRID 

incorrectly 

identified on 

study report

2070931 Blundell, K. (1991) A Small Scale Retrospective Ground-water 

Monitoring Study and Limited Prospective Field Dissipation 

Study with Acifluorfen-sodium, the Active Ingredient of Tackle 

Brand Herbicide and Blazer Brand Herbicide: Interim Report: 

Lab Project No.: 429.03: 91/5048. Unpublished study prepared 

by BASF Corp., in cooperation with Blasland & Bouck 

Engineering, P.C. 122 p. 

164-2 Aquatic field dissipation

MRID Citation Reference

76707 2068806 pg 

10 of pdf

Zogorski, W.J., III (1981) A Study To Measure the Dissipation 

Rate of Blazer Residues in Water from Treated Rice Fields: 

Technical Report No. 36H-81-8. (Unpublished study received 

May 27, 1981 under 707-149; submitted by Rohm & Haas Co., 

Philadelphia, Pa.; CDL:070115-G) 

43270801 DER not 

located

Jordan, J.; Nelsen, T. (1994) 1992 Blazer Herbicide Aquatic Use 

Dissipation Study: Lab Project Number: 94/5075: 92126: 

ER94017. Unpublished study prepared by Jensen Agricultural 

Consultants, Inc.; Stoneville Assoc., Inc. and Agvise Labs. 460 

p. 

164-5 Long term soil dissipation

MRID Citation Reference

41160001 2037582 Norris, F. (1989) A Small Scale Retrospective Groundwater 
57

Monitori- ng Study and Limited Prospective Field Dissipation 

Study with Acifluorfen-sodium...: File No. 40577: Protocol No. 

EC/P-89-001- 7. Unpublished study prepared by Rhone-Poulenc 

Ag Co. 360 p. 

165-1 Confined rotational crop

MRID Citation Reference

42330602 Panek, M. (1992) Carbon 14-Sodium Acifluorfen Confined 

Rotational Crop Study: Progress Report: Lab Project Number: 

92/5072. Unpublished study prepared by BASF Corp. 9 p. 

42785601 DER not 

located

Panek, M.; Geiger, D.; Reese, C. (1993) Confined Rotational 

Crop (carbon 14)-Sodium Acifluorfen: Lab Project Number: 

91058: M9307: 93/5061. Unpublished study prepared by BASF 

Corp. Agricultural Research Center and Agvise, Inc. 213 p. 

43372501 Amendment 

to 

42785601

Panek, M. (1994) (carbon 14)-Sodium Acifluorfen Confined 

Rotational Crop, Storage Stability of Acifluorfen and Metabolite 

1: Amendment to BASF Report No M9307: Lab Project 

Number: 94/5114: 91058: M9425. Unpublished study prepared 

by BASF Agricultural Research Center. 34 p. 

43666601 DER not 

located

Geiger, D.; Goetz, A. (1995) Further Characterization Analysis 

of Metabolite 1 from the (Carbon-14)-Sodium Acifluorfen 

Confined Rotational Crop: Lab Project Number: 94127: M9427: 

91058. Unpublished study prepared by BASF Corp. 55 p. 

122769

ACC 071326

2037627 Gemma, A.; Wargo, J.; Heinzelmann, G.; et al. (1982) Tackle 

Field Rotational Crop Study: The Potential Uptake of 14C-MC 

10978 in Various Crops Grown under Field Conditions in Soil 

Treated with 14C-MC 10978: ASD Report No. 82/042. 

(Unpublished study re- ceived Dec 20, 1982 under 359-708; 

submitted by Rhone-Poulenc, Inc., Monmouth Junction, NJ; 

CDL:071326-B)

156220

ACC 256167

2037640

2037641

Hutchinson, C. (1984) [Carbon-14] Tackle (MC-10978) 

Confined Rotat- ional Crop Study: Final Report: Project No. 

171-107. Unpub- lished study prepared by Wildlife International 

Ltd. 106 p.

164236

ACC 265702

2037643 Perez, G. (1986) Tackle Residue Data on Field Grown 

Rotational Crops (1982 - 1984): ASD No. 86/206: Ref No. 

86/BHL/463. Unpub- lished compilation prepared by RhonePoulenc Inc. 163 p.

2068708 

pages 43-57

Augenstein- and RogersonSeveral Rotational Crop Residue 

studies
58

165-2 Field rotational crop

MRID Citation Reference

156220 2037640 Hutchinson, C. (1984) [Carbon-14] Tackle (MC-10978) 

Confined Rotat- ional Crop Study: Final Report: Project No. 

171-107. Unpub- lished study prepared by Wildlife International 

Ltd. 106 p. 

92168034 Registrant 

summary

Keene, E. (1990) BASF Corporation Phase 3 Summary of MRID 

00107504. Residue Studies on Rotational Crops From Plots 

Treated with Carbon 14 Blazer Herbicide: Rohm and Haas 

Technical Report No. 310-86-76; 90/6149. Prepared by Rohm 

and Haas Company. 22 p. 

ACC 071326 2037626 Gemma, 1982 Greenhouse Rotational Crop study

165-3 Accumulation - irrig crop

MRID Citation Reference

164236 2037643 pg 

2

Perez, G. (1986) Tackle Residue Data on Field Grown 

Rotational Crops (1982 - 1984): ASD No. 86/206: Ref No. 

86/BHL/463. Unpub- lished compilation prepared by RhonePoulenc Inc. 163 p. 

165-4 Fish Bioacculmulation

122770 2037628 Thompson, C.; Cranor, W.; Lawman, K.; et al. (1981) Uptake, 

Depura- tion and Bioconcentration of 14C-MC 10978 by 

Bluegill Sun- fish ...: ABC Report # 26610. Final 

bioconcentration rept. (Unpublished study received Dec 20, 1982 

under 359-708; prepared by Analytical Bio Chemistry 

Laboratories, Inc., submitted by Rhone-Poulenc, Inc., Monmouth 

Junction, NJ; CDL:071327-A) 

122771 2037629 Forbis, A.; Boudreau, P.; Thompson, C.; et al. (1981) Uptake 

Depuration and Bioconcentration of MC-10978 by Channel 

Catfish (Ictalurus punctatus) in a Static System with Soil: ABC 

Report #26611. Final bioconcentration rept. (Unpublished study 

received Dec 20, 1982 under 359-708; prepared by Analytical 

Bio Chemistry Laboratories, Inc., submitted by Rhone-Poulenc, 

Inc., Monmouth Junction, NJ; CDL:071327-B) 

ACC 97722 2068708 pg 

58 in PDF E& G Bionomics 1977 Fish Bioacculmulation 

ACC 97722 2068708 pg Iwan, 1978 Bioconcentration Study with Catfish
59

62 in PDF

107505

ACC 097722

Check 

2068708

Fisher, J. (1978) Accumulation and Elimination of RH-6201 

Residues in Bluegill and Catfish: Agricultural Products Research 

Report No. 34-28. (Unpublished study received Dec 14, 1978 

under 707- 149; submitted by Rohm & Haas Co., Philadelphia, 

PA; CDL: 097722-A)

166-1 Ground water-small prospective

MRID Citation Reference

92168035 Registrant 

summary-of 

41172801 

Keene, E. (1990) BASF Corporation Phase 3 Summary of MRID 

41172801. A Small Scale Prospective Groundwater Monitoring 

Study with Acifluorfen-Sodium - The Active Ingredient in 

Tackle Herbicide and Blazer Herbicide: 90/6154. Prepared by 

RHONE-POULENC AG CO. 26 p. 

41172801 2037576 Norris, F. (1989) A Small Scale Prospective Field Dissipation 

and Groundwater Monitoring Study with Acifluorfen-Sodium, 

the Active Ingredient of Tackle Brand Herbicide and Blazer 

Brand Herbicide: Project ID: File No. 40576; Protocol No. MEF87-010. Unpublish- ed study prepared by Rhone-Poulenc Ag Co. 

813 p. 

41160001 2037582 Norris, F. (1989) A Small Scale Retrospective Groundwater 

Monitori- ng Study and Limited Prospective Field Dissipation 

Study with Acifluorfen-sodium...: File No. 40577: Protocol No. 

EC/P-89-001- 7. Unpublished study prepared by Rhone-Poulenc 

Ag Co. 360 p. 

42152201 2078945

5 studies in 

five states

2070931-

protocol

Hiscock, A.; Cooper, S. (1991) A Small Scale Retrospective and 

Limited Prospective Ground-Water Monitoring Study with Acifluorfen-Sodium, the Active Ingredient of Tackle Herbicide and 

Blazer Herbicide: Lab Project Number: 429.03: 894M11: 

91/5206. Unpublished study prepared by Rhone-Poulenc AG 

Co., Blasland and Bouck Engineers and BASF Corp. 415 p.

201-1 Droplet size spectrum

MRID Citation Reference

40036301 reviewed 

DER not 

located

Spicer, L. (1986) Tackle Herbicide, Sodium Acifluorfen: Droplet 

Size Spectrum Studies: Study No. ASD 86/224. Unpublished 

study prepared by New Mexico State Univ. 78 p. 

202-1 Drift field evaluation

MRID Citation Reference
60

40036302 reviewed 

DER not 

located

Merricks, D. (1986) Tackle Aerial Spray Drift Study: Lab. Proj. 

No. 1504. Unpublished study prepared by Agrisearch Inc. 92 p. 

92168040 Registrant 

summary

Keene, E. (1990) BASF Corporation Phase 3 Summary of MRID 

40036301. Tackle Herbicide, Sodium Acifluorfen Droplet Size 

Spectrum: Study No. 86/224; 90/6153. Prepared by RhonePoulenc Inc. 22 p. 

92168041 Registrant 

summary

Keene, E. (1990) BASF Corporation Phase 3 Summary of MRID 

40036302. Tackle Aerial Spray Drift Study: Project No. 1504; 

90/6152. Prepared by RHONE POULENC AG CO. 21 p. 

6.2. Submitted Ecotoxicity Studies

114402 Acifluorfen Na Salt Eco Effects Bibliography MRID-Doc# 

71-1 Avian Single Dose Oral Toxicity

MRID Citation Reference

83058 2063997 Fink, R. (1976) Final Report: Acute Oral LD50--Mallard Duck: Proj- ect 

No. 129-111. (Unpublished study received Jan 17, 1977 under 707-

EX-87; prepared by Wildlife International, Ltd., submitted by Rohm & 

Haas Co., Philadelphia, Pa.; CDL:095736-AB) 

122747 Fink, R.; Beavers, J.; Brown, R.; et al. (1981) Acute Oral LD50--

Mallard Duck: 10318001: MEHSL Study No. 2031-80. Final rept. 

(Unpublished study received Dec 20, 1982 under 359-708; prepared 

by Wildlife International, Ltd. and Washington College, submit- ted by 

Rhone-Poulenc, Inc., Monmouth Junction, NJ; CDL:071322-A) 

122748 2067127 Fink, R.; Beavers, J.; Brown, R.; et al. (1981) Acute Oral LD50--

Bobwhite Quail: 10318001: MEHSL Study No. 2021-80. Final rept. 

(Unpublished study received Dec 20, 1982 under 359-708; prepared 

by Wildlife International Ltd. and Washington College, submit- ted by 

Rhone-Poulenc, Inc., Monmouth Junction, NJ; CDL:071322-B) 

Test material= 25.6% ai Tackle 2S

92168001 Registrant 

summary

Weinstein, S.; Habig, C. (1990) BASF Corporation Phase 3 Summary 

of MRID 00122748. Acute Oral LD50--Bobwhite Quail 10318001: 

Wildlife International Ltd. Project No. 155-113; 90/6147. Prepared by 

Wildlife International Ltd. 12 p. 

71-2 Avian Dietary Toxicity

MRID Citation Reference

83059 2064001 Fink, R. (1976) Final Report: Eight-day Dietary LC50--Bobwhite Quail: 

Project No. 129-108. (Unpublished study received Jan 17, 1977 under 
61

707-EX-87; prepared by Wildlife International, Ltd., submitted by Rohm 

& Haas Co., Philadelphia, Pa.; CDL:095736-AC) 

122749 2067128 Fink, R.; Beavers, J.; Brown, R.; et al. (1981) Eight-day Dietary LC50--

Mallard Duck: 10318001: MEHSL Study No. 2011-80. Final rept. 

(Unpublished study received Dec 20, 1982 under 359-708; prepared 

by Wildlife International Ltd. and Washington College, submitted by 

Rhone-Poulenc, Inc., Monmouth Junction, NJ; CDL: 071322-C) 

122750 2067128 Fink, R.; Beavers, J.; Brown, R.; et al. (1981) Eight-day Dietary LC50--

Bobwhite Quail: 10318001: MEHSL Study No. 2001-80. Final rept. 

(Unpublished study received Dec 20, 1982 under 359-708; prepared 

by Wildlife International Ltd. and Washington College, submitted by 

Rhone-Poulenc, Inc., Monmouth Junction, NJ; CDL: 071322-D) 

161889 Registrant 

summary

Waggoner, T. (1984) Toxicology Review of Acifluorfen. Unpublished 

compilation prepared by Rhone-Poulenc Inc. 127 p. 

92168002 Registrant 

summary

Weinstein, S.; Habig, C. (1990) BASF Corporation Phase 3 Summary 

of MRID 00122750. Eight-Day Dietary LC50--Bobwhite Quail 

10318001: Wildlife International Ltd. Project #155-111; 90/6146. 

Prepared by Wildlife International Ltd. 11 p. 

92168003 Registrant 

summary

Weinstein, S.; Habig, C. (1990) BASF Corporation Phase 3 Summary

of MRID 00122749. Eight-Day Dietary LC50-Mallard Duck 10318001: 

Wildlife International Ltd. Project No. 155-112; 90/6145. Prepared by 

Wildlife International Ltd. 11 p. 

83060 2064004 Fink, R. (1976) Final Report: Eight-day Dietary LC50-Mallard Duck: 

Project No. 129-109. (Unpublished study received Jan 17, 1977 under 

707-EX-87; prepared by Wildlife International, Ltd., sub- mitted by 

Rohm & Haas Co., Philadelphia, Pa.; CDL:095736-AD) 

Acc. 071322 Possibly 

122750

Fink, R. (1981) Eight-Day Dietary LC50 to Bobwhite Quail; Project # 

155-111; Prepared by Wildlife International LTD for Rhone-Poulenc 

Inc., P.O. Box 125, Monmouth Junction, N.J. 08852 Acc. #071322

71-4 Avian Reproduction

MRID Citation Reference

107491 2064003 Piccirillo, V.; Najarian, G. (1978) One-generation Reproduction Study 

in Bobwhite Quail: RH-6201. Final rept. (Unpublished study received 

Dec 14, 1978 under 707-149; prepared by Hazleton Laboratories 

America, Inc., submitted by Rohm & Haas Co., Philadelphia, PA; 

CDL:097718-B) 

107492 2064002 Piccirillo, V.; Najarian, G. (1978) Final Report: One-generation 

Reproduction Study in Mallard Ducks: ?RH-6201|: Project No. 417-

373. (Unpublished study received Dec 14, 1978 under 707-149; 

prepared by Hazleton Laboratories America, Inc., submitted by Rohm 

& Haas Co., Philadelphia, PA; CDL:097718-C) 

72-1 Acute Toxicity to Freshwater Fish

MRID Citation Reference
62

71901 2063992 Buccafusco, R.J. (1976) Acute Toxicity of RH-6201LC to Bluegill 

(~Lepomis macrochirus~), Rainbow Trout (~Salmo gairdneri~) and the 

Water Flea (~Daphnia magna~). (Unpublished study re- ceived Jan 

17, 1977 under 707-EX-87; prepared by EG & G, Bio- nomics, 

submitted by Rohm & Haas Co., Philadelphia, Pa.; CDL: 095736-AA) 

107494 2063994 Kuc, W. (1977) The Acute Toxicity of RH 6201, Lot #SW 77/0101 

(42.4% Active Ingredient) to the Channel Catfish, Ictalurus punctatus 

(Rafinesque): UCES Proj. # 11506-33-03. (Unpublished study received 

Dec 14, 1978 under 707-149; prepared by Union Carbide Corp., 

submitted by Rohm & Haas Co., Philadelphia, PA; CDL:097718-E) 

122751 2067129 LeBlanc, G.; Sousa, J. (1981) Acute Toxicity of 10318001 to Blue- gill 

...: Report #BW-81-1-811. (Unpublished study received Dec 20, 1982 

under 359-708; prepared by EG & G, Bionomics, submitted by RhonePoulenc, Inc., Monmouth Junction, NJ; CDL: 071322-E) 

122752 2067130 LeBlanc, G.; Sousa, J. (1981) Acute Toxicity of 10318001 to Rainbow 

Trout ...: Report #BW-81-2-815. (Unpublished study received Dec 20, 

1982 under 359-708; prepared by EG & G Bionomics, sub- mitted by 

Rhone-Poulenc, Inc., Monmouth Junction, NJ; CDL: 071322-F) 

124222 2064006 Spare, W.; Hutchinson, C. (1982) Early Life Stage Study with the 

Fathead Minnow ... Exposed to Blazer Aqueous Technical: Project No. 

81-3-10060. Rev. final rept. (Unpublished study received Jan 21, 1983 

under 707-149; prepared by Biospherics, Inc., sub- mitted by Rohm & 

Haas Co., Philadelphia, PA; CDL:071374-A) 

92168054 Registrant 

summary

Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 

00122751. Sodium Acifluorfen--Acute Toxicity Test Freshwater Fish: 

Bluegill Sunfish: Report No. BW-81-1-811; BASF Reg. Doc. No. 

90/6325. Prepared by EG & G Bionomics. 12 p. 

92168055 Registrant 

summary

Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 

00122752. Sodium Acifluorfen - Acute Toxicity Test: Freshwater Fish: 

Rainbow Trout: Report No. BW-81-2-815; BASF Reg. Doc. No. 

90/6324. Prepared by EG & G Bionomics. 12 p. 

107493 Buccafusco, R. (1977) Acute Toxicity of RH-6201 Technical to Bluegill (Lepomis macrochirus). (Unpublished study received Dec 14, 1978 

under 707-149; prepared by EG & G, Bionomics, submitted by Rohm 

& Haas Co., Philadelphia, PA; CDL:097718-D)

72-2 Acute Toxicity to Freshwater Invertebrates

MRID Citation Reference

71901 2063992 Buccafusco, R.J. (1976) Acute Toxicity of RH-6201LC to Bluegill 

(~Lepomis macrochirus~), Rainbow Trout (~Salmo gairdneri~) and the 

Water Flea (~Daphnia magna~). (Unpublished study re- ceived Jan 

17, 1977 under 707-EX-87; prepared by EG & G, Bio- nomics, 

submitted by Rohm & Haas Co., Philadelphia, Pa.; CDL: 095736-AA) 

111963 2063996 Vilkas, A. (1977) Acute Toxicity of RH 6201, Lot #SW 77/0101 to the 

Freshwater Clam Elliptio complanata: UCES Project # 11506-33-03. 

(Unpublished study received Dec 14, 1978 under 707-149; prepared 

by Union Carbide Corp., submitted by Rohm & Haas Co., Philadelphia, PA; CDL:097718-H) 
63

122754 2067132 LeBlanc, G.; Surprenant, D. (1981) Acute Toxicity of 10318001 to the 

Water Flea ...: Report #BW-81-1-807. (Unpublished study received 

Dec 20, 1982 under 359-708; prepared by EG & G, Bio- nomics, 

submitted by Rhone-Poulenc, Inc., Monmouth Junction, NJ; 

CDL:071322-H) 

92168004 Registrant 

summary

Weinstein, S.; Habig, C. (1990) BASF Corporation Phase 3 Summary 

of MRID 00122754. Acute Toxicity of 10318001 to the Water Flea 

(Daphnia magna): EG&G, Bionomics Project No. BW-81-1-807; 

90/6144. Prepared by EG&G, Bionomics. 11 p. 

72-3 Acute Toxicity to Estuarine/Marine Organisms

MRID Citation Reference

107495 2064000 Calmbacher, C. (1978) Acute Toxicity of RH6201 LC Formulation JR 

6412 Lot #PL76/8111 (39.8% Active Ingredient) Fiddler Crab, Uca 

pugilator: UCES Project No. 11506-33-25. (Unpublished study received Dec 14, 1978 under 707-149; prepared by Union Carbide 

Corp., submitted by Rohm & Haas Co., Philadelphia, PA; CDL: 

097718-F) 

111962 2063995 Vilkas, A. (1977) Acute Toxicity of RH 6201, Lot #SW 77/0101 (42.4% 

Active Ingredient) to the Grass Shrimp, Palaemonetes pugio: UCES 

Proj. # 11506-33-03. (Unpublished study received Dec 14, 1978 under 

707-149; prepared by Union Carbide Corp., submitted by Rohm & 

Haas Co., Philadelphia, PA; CDL:097718-G) 

111964 2063991 Vilkas, A. (1977) The Acute Toxicity of RH 6201, Lot #SW 77/0101 to 

the Eastern Oyster Crassostrea virginica: UCES Proj. # 11506- 33-03. 

(Unpublished study received Dec 14, 1978 under 707-149; prepared 

by Union Carbide Corp., submitted by Rohm & Haas Co., Philadelphia, 

PA; CDL:097718-I) 

122753 2067131 Ward, G. (1981) Acute Toxicity of 1993-80 (Sample No. 10318001) to 

Sheepshead Minnows ...: Report No. BP-81-6-111. (Unpublished 

study received Dec 20, 1982 under 359-708; prepared by EG & G 

Bionomics, submitted by Rhone-Poulenc, Inc., Monmouth Junction, 

NJ; CDL:071322-G) 

122755 2067133 Hollister, T. (1981) Acute Toxicity of 1992-80 (Sample No. 10318001) 

to Mysid Shrimp ...: Report No. BP-81-6-97. (Unpublished study 

received Dec 20, 1982 under 359-708; prepared by EG & G 

Bionomics, submitted by Rhone-Poulenc, Inc., Monmouth Junction, 

NJ; CDL:071322-I) 

124223 2064012 Spare, W.; Hutchinson, C. (1982) The Acute Toxicity of Blazer 

Aqueous Technical 43% to the Sheepshead Minnow ...: Project No. 

81- 39709. Final rept. (Unpublished study received Jan 21, 1983 under 

707-149; prepared by Biospherics, Inc., submitted by Rohm & Haas 

Co., Philadelphia, PA; CDL:071374-B) 

41891207 2063998 Dionne, E. (1991) Acifluorfen--Sodium (BAS9048 H)-Acute Toxicity to 

Eastern Oyster (Crassostrea virginica) Under Flow-through Conditions: Final Report: Lab Project Number: 91/4/3736: ER91012: E9012. 

Unpublished study prepared by Springborn Laboratories, Inc. 60 p. 
64

42185901 Raw data –

supplemental 

information 

for 41891207

Dionne, E. (1991) Raw Data Associated with the Report Titled: 

(Acifluorfen-Sodium (BAS 9048 H))--Acute Toxicity to Eastern Oyster 

(Crassostrea virginica) Under Flow Through Conditions: Lab Project 

Number: 91/5215: 91/5072: 91-4-3736. Unpublished study prepared 

by Springborn Laboratories, Inc. 153 p. 

92168056 Registrant 

summary

Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 

00122753. Acifluorfen - Acute Toxicity Test for Estuarine Fish: 

Sheepshead Minnow: Report No. BP-81-6-111; BASF Reg. Doc. No. 

90/6327. Prepared by EG & G Bionomics. 13 p. 

92168057 Registrant 

summary

Eubanks, M. (1990) BASF Corporation Phase 3 Summary of MRID 

00122755. Acifluorfen--Acute Toxicity Test for Shrimp: Mysid: Report 

No. BP-81-6-87; Reg. Doc. No. 90/6326. Prepared by EG & G 

Bionomics. 12 p. 

72-4 Fish Early Life Stage/Aquatic Invertebrate Life Cycle Study

MRID Citation Reference

96558 Compilation Rohm & Haas Company (1982) Preliminary Data Package: ?Blazer|. 

(Compilation; unpublished study, including project no. 81-3- 10060 and 

letters dated Mar 4, 1982 from W.C. Spare to Isadore J. Morici and 

Mar 10, 1982 from S.S. Burke to T.D. Rogerson, received Mar 11, 

1982 under 707-149; CDL:070712-A) 

107493 2063993 Buccafusco, R. (1977) Acute Toxicity of RH-6201 Technical to Bluegill (Lepomis macrochirus). (Unpublished study received Dec 14, 1978 

under 707-149; prepared by EG & G, Bionomics, submitted by Rohm 

& Haas Co., Philadelphia, PA; CDL:097718-D) 

124222 2064006 Spare, W.; Hutchinson, C. (1982) Early Life Stage Study with the 

Fathead Minnow ... Exposed to Blazer Aqueous Technical: Project No. 

81-3-10060. Rev. final rept. (Unpublished study received Jan 21, 1983 

under 707-149; prepared by Biospherics, Inc., sub- mitted by Rohm & 

Haas Co., Philadelphia, PA; CDL:071374-A) 

92168005 Registrant 

summary

Clark, J. (1990) BASF Corporation Phase 3 Summary of MRID 

00124222. Early Life Stage Study with the Fathead Minnow 

(Pimephales promelas) Exposed to BLAZER Aqueous Technical: 

90/6323. Prepared by Biospherics Incorporated. 13 p. 

123-1 850.4150 Terrestrial plant toxicity, Tier 1 (vegetative vigor)

MRID Citation Reference

46431401 Porch, J.; Krueger, H.; Holmes, C. (2004) BAS 9048 AH (Ultra Blazer): 

A Toxicity Test To Determine The Effects of the Test Substance on 

Vegetative Vigor of Ten Species of Plants: Final Report. Project 

Number: 147/221, 136139, 2004/5000788. Unpublished study 

prepared by Wildlife International, Ltd. 144 p.

123-2 850.4250 Vegetative vigor, Tier II

MRID Citation Reference
65

46431401 Porch, J.; Krueger, H.; Holmes, C. (2004) BAS 9048 AH (Ultra Blazer): 

A Toxicity Test To Determine The Effects of the Test Substance on 

Vegetative Vigor of Ten Species of Plants: Final Report. Project 

Number: 147/221, 136139, 2004/5000788. Unpublished study 

prepared by Wildlife International, Ltd. 144 p.

850.3020 Honey bee acute contact toxicity

MRID Citation Reference

46650202 Palmer, S.; Krueger, H.; Holmes, C. (2001) Sodium Acifluorfen: An Acute 

Contact Toxicity Study with the Honey Bee. Project Number: 147/198, 

64274, 2001/5002329. Unpublished study prepared by Wildlife International, 

Ltd. 19 p.
66