UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OCT 0 6 2014 

MEMORANDUM 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

SUBJECT: BEAD Chemical Profile (BCP) for Registration Review: Phenmedipham 

FROM: 

THRU: 

(098701) ~ 

BB~l1 P~llalips, Agr

1 10 og1c Ana ys1s 

o~oBmist ranc h ~ !"'" r- J 

Sepehr 

Science 

Haddad, 

Information 

Envirorunental 

and Analysis 

Protection 

Branch 

Specialist ff/,..... ~ 

Diann Sims, Chief 

Science Information and Analysis Branch 

Timothy Kiely, Chief Q_ (Jv..__~ Economic Analysis Branch '-J. J _ Biological and Economic Analysis Division (75 ~ 

TO: Miguel A. Zavala, Chemical Review Manager 

Risk Management and Implementation Branch III 

Pesticide Re-evaluation Division (7508P) 

Peer Review Panel date: September 10,2014 

SUMMARY 

Phenmedipham was first registered in the United States as an herbicide in 1970 (USEP A, 2005). 

A Reregistration Eligibility Decision (RED) was completed for phenmedipham in 2005. 

Based on private market usage data from 1998-2012, usage averaged approximately 120,000 

pounds active ingredient (a.i.) applied annually on approximately 1.9 million acres treated. The 
average a.i. rate over this time period was 0.064 pounds a.i./acre. A Screening Level Usage 

Analysis (SLUA) was prepared by BEAD for this chemical in 2014 that provides the percent 

crop treated for spinach and sugar beets. For phenmedipham, during the SLUA timeframe of 

2004-2012, usage for spinach averaged 3,000 lbs a.i. with an average 10 percent crop treated, 

and for sugar beets (the major use), usage averaged 80,000 lbs. a.i. with an average percent crop 

treated of 45 percent. There are no non-agricultural uses of phenmedipham. 

Phenmedipham is a postemergence herbicide that is used to control small seeded broadleaf 

weeds in spinach and sugar beets. This herbicide is most often applied in combination with other 

broadleaf and grass herbicides. Combinations with other herbicides provide for a broader 

spectrum of weeds control. Given relative low usage of phenmedipham on spinach this 

herbicide may have limited utility for this crop. A major portion of the sugar beet crop is treated 

with this herbicide and it is likely that this herbicide is important for weed control in this crop. 

However, the number of acres treated with this herbicide has declined since 2007, which may 

indicate that other herbicides are being used as alternatives. 

INTRODUCTION 

The Biological and Economic Analysis Division (BEAD) Chemical Profile (BCP) provides an 

overview of the pest management roles and quantitative usage information for phenmedipham. 

The BCP includes summaries of previous BEAD products and available public and/or private 

use and usage data for phenmedipham to describe the role of this chemical in pest management. 

Additional information on use is available the Screening Level Usage Analysis (SLUA). 

Information provided in this BCP may be used by stakeholders (e.g., users and registrants), OPP 

risk and benefit assessors, OPP risk managers, and the general public during the Registration 

Review process of this pesticide. 

Phenmedipham is a phenylcarbamate (Group 5) herbicide according to the Weed Science Society 

of America classification. Herbicides in this group control weeds by inhibiting photosynthesis 

by blocking the fixation of C02, which subsequently blocks the production of the energy 

products ofphotosynthesis (e.g. ATP) (Senseman, 2007). 

USE SITES 

Agricultural Use Sites 

Phenmedipham registered agricultural use sites include: beets and spinach 

Non-Agricultural Use Sites 

There are no registered non-agricultural use sites for phenmedipham. 

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FORMULATIONS AND APPLICATION METHODS 

Phenmedipham is formulated as an emulsifiable concentrate and can be applied as a broadcast or 

spray treatment with ground, aerial, or sprayer equipment. Foliar applications are made 

postemergence (to the plant) .. 

HISTORY OF PHENMEDIPHAM and BEAD PRODUCTS 

Phenmedipham was first registered in the United States as an herbicide in 1970 (USEP A, 2005). 

A Screening Level Usage Analysis (SLUA) was prepared by BEAD for this chemical in 2014 

that provides the percent crop treated for spinach and sugar beets (Table 4). A Reregistration 

Eligibility Decision (RED) was completed for phenmedipham in 2005. A search of BEAD's 

Official Records database for BEAD benefits assessments specifically for phenmedipham did not 

find any records of prior BEAD assessments specifically for this chemical in the last 10 years. 

A search of BEAD's Official Records and the OPP Section_18 database did not find any Section 

18 requests for phenmedipham in the last 10 years. Emergency exemptions may indicate that 

there is a need for a particular chemical that is not registered for use on a particular site. An 

emergency exemption request may yield information about a particular chemical's importance or 

value that is not found in other EPA records. However, a lack of Section 18 assessments by 

BEAD does not specifically indicate the relative importance of the chemical. 

USAGE 

Agricultural Usage 

Based on private market usage data from 1998-2012, usage averaged approximately 120,000 

pounds active ingredient (a.i.) applied annually on approximately 1.9 million acres treated. The 

average a.i. rate over this time period was 0.064 pounds a.i./acre. Figure 1 presents 

phenmedipham usage in pounds a.i., and Figure 2 shows total area treated in acres over the 1998-

2012 timeframe (Proprietary Data, 1998-2012). Figures 1 and 2 show that over this time period 

in terms of pounds applied and acres treated !here has been a sharp decrease in use from 2007 

through 2012 while use had remained fairly steady from 1998 through 2007. 

Based on private market data for agronomic crops, phenmedipham is used to control broadleaf 

weeds in spinach and sugar beet production (Proprietary Data, 2012). Neither of these crops 

competes well with weeds and as a result can suffer yield loss due to competition (Dexter, 

undated; Smith et al., 2009). Due to the relatively small size of these crops as well as their being 

slow to shade the ground between the planted rows, any weeds that are allowed to grow will 

ultimately out-compete these crops for needed resources. Phenmedipham is applied 

postemergence in both crops in order to control broadleaf weeds such as pigweeds, kochia, and 

lambs quarter (Proprietary Data, 2012). Because spinach and sugar beets can be sensitive to this 

herbicide, applications are made only after the first four leaves of the crop plants have fully 

developed (Dexter, No Date Provided; Smith et al., 2009). Applications of phenmedipham in 

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spinach and sugar beets can be applied earlier, approximately two leaf stage, if the applications 

are made using two applications each at a lower rate. (Dexter, undated; Smith et al., 2009). This 

herbicide is most often applied in combination with other broadleaf and grass herbicides. 

Combinations with other herbicides provide for a broader spectrum of weeds control. Given 

that, on average, only 10% ofthe spinach crop is treated with phenmedipham, this herbicide may 

have limited utility for this crop. However, the fact that an average of 45% of the sugar beet 

crop is treated with phenmedipham, it is apparent that this herbicide is important for weed 

control in this crop. The number of acres treated with this herbicide has declined since 2007, 

which may indicate that the overall need for this product may be declining (Figure 2). This may 

be, at least in part (if not primarily), because of the dramatic uptake by growers of genetically 

modified sugar beet tolerant to glyphosate, which now constitutes over 95% of sugar beet 

planting (e.g., Oeschger et al., 2011). 

250,000 

0 

FIGURE 1. Phenmedipham Usage in Pounds Active Ingredient (1998-2012) 

Source: Proprietary Data, 1998-2012 

3500000 

0 

FIGURE 2. Phenmedipham Total Area Treated in Acres (1998~2012) 

Source: Proprietary Data, 1998-2012 

Page4 
Since the Reregistration Eligibility Decision (RED) was issued in 2005, the two periods below 

(1999-2005 and 2006-2012) were selected to show any change in use resulting from the RED. 

Table 1. Comparison of Crops with Highest Use ofPhenmedipham- Percent ofTotal Lbs. 

Applied (1999-2005 and 2006-2012) 

1999-2005 2006-2012 

Average annual= 170,000 lbs/yr Average annual= 61,000 lbs/yr 

Crop %Lbs Crop %Lbs 

Sugar Beets 99% Sugar Beets 95% 

Spinach 1% Spinach 5% 

Source: Proprietary Data, 1999-2012. 

Table 1 shows that the crop with the most pounds applied during both the 1999-2005 and 2006-

2012 timeframes has been sugar beets accounting for approximately 95-99 percent of total 

pounds applied. The average annual usage in pounds has decreased approximately 64 percent 

from 170,000 lbs/year to approximately 61,000 lbs/year in the 2006-2012 timeframe. 

Table 2. Comparison of States with Highest Use of Phenmedipham- Percent of Total Lbs. 

Applied (1999-2005 and 2006-2012) 

1999-2005 2006-2012 

Average annual= 170,000 lbs/yr Average annual= 61,000 lbs/yr 

State %Lbs State %Lbs 

Minnesota 33% Minnesota 45% 

North Dakota 22% North Dakota 14% 

Michigan 14% Michigan 14% 

Idaho 14% Idaho 9% 

Other 17% Other 18% 

TOTAL 100% TOTAL 100% 

Other states in both time periods includes 12 additional states. 

Source: Proprietary Data, 1999-2012 

As shown in Table 2, Minnesota, North Dakota, Michigan, and Idaho are the top states with the 

highest use of phenmedipham accounting for approximately 82 percent of total pounds applied in 

both timeframes, even though total pounds applied has dropped 64 percent between the two 

periods. 

Application Rates and Percent Crop Treated 

The average a.i. rate for the top crop (sugar beets) in terms of pounds a.i. applied was 0.06lbs 

a.i./acre. The average a.i. rate for spinach the only other registered use is 0.75 lbs a.i./acre as 

shown in Table 3. 

Page 5 
T a e . bl 3 Ph enme d' 1p1 h am u seon T C op rops: A verage AIR .. ate, 2006 -2012 

Annual Average Annual Average A vg. A.I. Rate (lbs Crop Total Acres Pounds Treated* a.i./acres) 

Sugar Beets 57,000 956,000 0.06 

Spinach 3,300 4,400 0.75 

*Total Acres Treated sums all acres treated for a crop, mcludmg those acres that recetve multtple treatments. 

Source: Proprietary Data, 2006-2012 

For phenmedipham, during the timeframe of2004-2012, usage on spinach averaged 10 percent 

crop treated, and usage on sugar beets (the major use) averaged 45 percent crop treated. (See 

Table 4) Given that phenmedipham usage is declining as shown in Figures 1 and 2, the percent 

crop treated might be lower in recent years than the averages over the 2004-2012 time frame. 

T a e . bl 4 Ph en me d' 1p1 h am: p ercen t crop t t rea e d, 2004-2012 

Cro_p Percent Crop Treated 

Sugar Beets 45 

Spinach 10 

Source: BEAD, 2014 

Geographic Distribution ofPhenmedip_ham Use 

Figure 3 provides a very broad geographical view of the average annual amount (in pounds) of 

phenmedipham applied per 1,000 acres of crop acres grown. The calculated values presented in 

the map are not equivalent to an application rate (lb ai/ A), therefore, the map may show areas of 

high use intensity that do not correspond to the states listed in Table 2 since those are the states 

with the highest use of phenmedipham based on pounds active ingredient applied. 

As shown in the map, Minnesota and New Jersey depict a high use intensity of acres treated with 

phenmedipham. Please see Appendix I for a more detailed explanation of the information 

presented on the map. 

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Pounds Active Ingredient 

per 1,000 Crop Acres Grown 

0 <0.1 

0.1 -0.2 

0.3 -0_4 

0.5 

- >05 

0 NoOata 

FIGURE 3. Annual Average Agricultural Use Intensity ofPhenmedipham (2008-2012) 

Non-Agricultural Usage 

There are no non-agricultural uses of phenmedipham. 

DATA. NEEDS 

The Agency currently does not have complete information for phenmedipham. Obtaining the 

following information may improve future assessments conducted by the Agency related to the 

use and importance of this herbicide: 

• Information regarding any specific attributes of this herbicide in controlling weeds in 

either spinach or sugar beet production 

Page7 
REFERENCES 

BEAD. 2014. Phenmedipham Screening Level Usage Analysis. Biological and Economic 

Analysis Division, Office of Pesticide Programs, US Environmental Protection Agency. 

Dexter, A. (undated). Weed Control in sugarbeet. Available at: 

http://appliedweeds.cfans.umn.edu/weedbull/Sugarbeet.pdf Accessed June 2014 

Oeschger, T., Schweikhardt, D., and Thornsbury, S. 2011. Regulation of glyphosate-resistant 

sugar beets: Challenges and uncertainty. Choices-Magazine of Food, Farm and Resource 

Issues. 3rd Quarter 2011 26(3). http://www.choicesmagazine.org/choicesmagazine/submitted-articles/regulation•of-glyphosate-resistant-sugar-beets-challenges-anduncertainty 

Proprietary Data. 1998-2012. (pesticide agricultural usage data) 

Senseman, S.A. 2007. Herbicide Hand Book Ninth Edition. Weed Sci. Soc. of Am. 810 E. 

lOth Street, Lawrence, KS 66044-8897. U.S.A. 

Smith, R., S. Fennimore, and M. LeStrange. 2009. Spinach Integrated Weed Management. UC 

Pest Management Guidelines. Available at: 

http://www.ipm.ucdavis.edu/PMG/r732700111.html. Accessed June 2014. 

USEPA. 2005. Reregistration Eligibility Decision (RED) for Phenmedipham. 

Page 8 -
APPENDIX I 

The map included herein is primarily for the use of the risk assessors in the Environmental Fate 

and Effects Division. The map provides a very broad geographical view of the average annual 

amount (in pounds) of the active ingredient applied per 1 ,000 acres of crop acres grown. These 

data are included in the maps because risk assessors are interested in the amount of a pesticide 

used across agricultural land. The calculated values presented in the map are not equivalent to 

an application rate (lb ail A). 

The data used to make these maps have several limitations. Any interpretation of the maps 

should consider the underlying data and the associated limitations carefully. · 

The numerator (annual average pounds applied) is based on private market surveys of pesticide 

use in agriculture averaged over the last five years (Proprietary Data, 2008-2012). These surveys 

cover about 60 crops and are targeted in states that produce the majority of the crop. Although 

the surveys capture most of the use of a particular active ingredient in agriculture, there are 

several limitations to these surveys. 

• States with minor production of a surveyed crop are not sampled 

• Not all types of pesticides are surveyed in every crop in every year 

• Many specialty crops with very small acreages are not included in the survey 

The result of th~se limitations is that states that show no usage may actually have a small amount 

of the active ingredient being used. In some cases the displayed use intensity may be distorted 

because the surveyed crops and the reported pesticide usage may not accurately represent the 

actual pesticide usage on the crops produced in the state. 

The denominator (1,000 crop acres grown) was also obtained from the same private market 

survey database. The "Crop Acres Grown" variable represents the total acres grown in a given 

state of all of the surveyed crops. This value is independent of pesticide usage and pesticide 

registration. It is important to note that the surveyed crops (about 60) are sampled from states 

that are major producers of each crop. Therefore, there are cases where the actual crop acreage in 

a state is higher than that reported by crop acres grown in the survey because either that state 

and/or crop was not included in the survey. 

The reader should pay particular attention to the figure legends and realize that a map prepared 

for a particular chemical is not directly comparable to a map prepared for a different chemical as 

the legend bins will likely be different. 

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