UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

DEC 12 20a 

MEMORANDUM 

~ .; . 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

SUBJECT: BEAD Chemical Profile (BCP) for Registration Review: MCPA Case (030501, 

030511, 030502,030516,030563 and 030564) 

FROM: 

THRU: 

Sunil Ratnayake, Ph.D., Biologist /lL() \_ 0 

Biological Analysis Branch l c . ~ '\ ;} ~ 

Jihad Alsadek, Ph.D., Economist J d..J A-t-AL,Ut{ 

Science Information and Analysis Branch 

Economic 

Derek Berwald

Analysis 

, Ph.D.

Branch 

, Economist 

~ 

~ 

~ // -

Biological and Economic Analysis Division (7503P) 

Arnet Jones, Chief 

Biological Analysis Branch 

Diann Sims, Chief 

Science Information and Anal:tysis Branch ~ 

Timothy Kiely, Chief ~ 

Economic Analysis Branch 

Biological and Economic Ana y Division (7 P) 

TO: Christina Scheltema, Chemical Review Manager 

Risk Management and Implementation Branch 3 

Pesticide Re-evaluation Division (7508P) 

Peer Review Panel date: August 14, 2013 
SUMMARY 

MCPA (2-methyl-4-chlorophenoxyacetic acid) is a selective, post-emergence systemic herbicide 

used for the control of annual and perennial broadleaf weeds. This herbicide was first registered 

in the United States in 1973 (USEPA, 2004). MCPA belongs to the phenoxy carboxylic acid 

family and according to the Weed Science Society of America (WSSA) mechanism of action 

classification; it belongs to the synthetic auxins (Group 4). Phenoxy herbicides act by mimicking 

the action of natural hormones and produce uncontrolled cell division and plant growth. MCP A is 

absorbed by the foliage and roots and translocated throughout the weed. The mechanism of 

action of this herbicide appears to affect the cell wall plasticity and nucleic acids (DNA, RNA) 

metabolism. Products ofMCPA are available in salt, ester, or amine forms. Ester form ofMCPA 

is more volatile than other formulations. MCP A is used in mixture with many other products to 

achieve a wider spectrum of weed control. 

Registered agricultural use sites of MCP A include: barley, flax, grasses grown for seed, oats, 

pastureland, peas (unspecified), rye, and wheat. The registered non-agricultural use sites of 

MCP A include: nonagricultural areas, uncultivated areas/soils, ornamental lawns and turf. 

There are no reported usage data for some of the registered crops such as flax because they are 

not surveyed. It is mainly used on wheat and barley in addition to other crops such as oats and 

green peas. The available data on MCP A use on non-agricultural sites (Kline 2002, 2004 and 

2006) show changes, but not in a consistent direction. The recent use of MCPA shows 1.3 

million lbs. a.i. used on ornamental lawns, (Kline 2011). 

INTRODUCTION 

The purpose of this document is to convey usage information and a broad overview of the pest 

management roles of pesticides that are beginning to undergo registration review. The 

anticipated audience consists of the team of EPA staff currently evaluating the registration status 

ofMCPA and eventually the general public. This document builds upon the data already 

provided in the usage and label use data packages that are also provided to Registration Review 

teams by BEAD. The document is based on information and data available to BEAD as of July 

241h of2013. This is a case level BCP where there are many PC codes, some of which have 

active products and others do not. The following PC codes do not have active products: 030553, 

030556 and 030562. The rest of the PC codes have active products. 

USE SITES 

Agricultural Use Sites 

MCPA registered agricultural use sites include: barley, flax, grasses grown for seed, oats, 

pastureland, peas (unspecified), rye and wheat. (There are no reported usage data for some of 

the registered crops such as flax because they are not surveyed.) 

Page2 
Non-Agricultural Use Sites 

MCP A registered non-agricultural use sites include: nonagricultural areas, uncultivated 

areas/soils, ornamental lawns and turf. 

COMMON FORMULATIONS AND APPLICATION METHODS 

Formulations include granular, emulsifiable concentrates, soluble concentrate/liquids and wettable 

powders. MCPA can be applied using aircraft, tractor mounted ground sprayers, broadcast spreaders, 

and hand-held sprayers. 

HISTORY OF MCPA AND BEAD PRODUCTS 

BEAD has not performed any assessments of MCPA in the past, other than Screening Level 

Usage Analysis (SLUA), which shows that the percent of the crop treated is above 20% in both 

wheat and barley, and above 15% in green peas. 

MCPA USAGE 

Agricultural Usage Trends: 

1998-2011 

As shown in Figure 1, agricultural usage ofMCPA, in both total area treated (TAT) in acres and 

total pounds in active ingredient applied, has been trending down since 1998. From 1998 to 

2011, an annual average of approximately 3 million pounds of MCP A was applied to agricultural 

crops. An average of about 10 million acres was treated annually, and the average application 

rate was 0.3 lbs. a.i. per acre. The average application rate stayed the same for the time periods, 

1998-2005 and 2006-201 1. Because the use in both pounds applied and area treated has been 

trending down, use in recent years is below the average reported above. 

Page 3 
FIGURE 1. MCPA Total Area Treated in Acres & Total Pounds in Active Ingredient 

A lied (1998-2011) 

14,000,000 

Total Pounds 

Applied & Total 

Acres Treated 

----··-·---

0 -------,....------..----.,---,.. ....., . -· ---·-~-

~ ~ o ~ N m ~ ~ ~ ~ ~ ~ o ~ 

~ ~ 0 0 0 0 0 0 0 0 0 0 ~ ~ 

~ ~ 0 0 0 0 0 0 0 0 0 0 0 0 ~ ~ N N N N N N N N N N N N 

Years 

BS 

.,._TAT 

·-----· -·---·-·-------·-.. - ·-- ·---·----' 

Source: Proprietary Data, 1998-2011 

2007-2011 

From 2007 to 2011, an average of2 million pounds ofMCPA was applied annually to 8 million 

acres at an average application rate of 0.25 lbs. a.i. per acre. 

Table 1 shows that the vast majority ofMCPA use is on wheat, with spring wheat accounting for 

more than half of the use both in terms of pounds applied and acres treated. Barley is the second 

most widely treated crop. Thirty percent of barley, 5 percent of oats, and 15 percent of green 

peas are treated on average with MCPA, according to the 2013 Screening Level Usage Analysis 

(SLUA). The SLUA indicates that about 20 percent ofwheat acreage is treated with MCPA. 

Proprietary data (2007-201 1) show 37% of spring wheat and 4% of winter wheat are treated 

with MCPA, as shown in Table 1. 

Table 1. Crops with Highest Use of MCP A- Percent of Total Lbs Active Ingredient 

A .pplied and Total Area Treated (TAT) in Acres, 2007-2011 

Crop Percent of Percent of Crop Percent of Total 

Pounds Treated Area Treated 

Applied 

Spring Wheat 60 37%a 64 

Winter Wheat 25 4%a 23 

Barley 12 30% 12 

Green Peas 0.32 15% 0.35 

Page 4 
Source: Proprietary Data, 2007-2011 

a EPA's SLUA shows a percent crop treated on wheat between 20 and 40%, but does not distinguish between spring 

and winter wheat. However, the percent crop treated can be approximated. If about 8 million acres are treated (see 

above), then if23% ofMCPA total acres treated are on winter wheat then about 1.8 million acres of winter wheat 

are treated. If 64% of acres treated are on spring wheat, then about 5 million acres of spring wheat are treated. 

From 2007 - 2011, an average of 42.5 million acres of winter wheat were planted annually, so about 4% of the 

winter wheat crop is treated. Over the same period, an average of about I 3.4 million acres of spring wheat were 

planted annually, so about 37% of the spring wheat crop was treated with MCPA on average. 

Table 2 shows the states with the greatest use of MCP A. These states are concentrated in the 

Northern and Northwestern parts of the country, where wheat (especially spring wheat) and 

barley are common crops. The percent of total area treated in Montana is greater than the 

percent of poundage used, while the percent ofMCPA pounds used in Idaho is greater than the 

percent of total area treated. This implies that application rates are slightly higher than average 

in Idaho, and slightly lower in Montana. These differences in rates are likely due to the use of 

different formulations or to the use of tank- mixed products. 

Table 2. Comparison of States with Highest Use of MCP A- Percent 

OfT ota ILb s. A lPP.le r d an dT ota lA rea T rea t e d' ID A cres, 20072011 - State Percent of Pounds Percent Total Area Treated 

Applied 

North Dakota 34 34 

Montana 16 18 

Minnesota 13 13 

Washington 10 10 

Idaho 9 8 

Source: Proprietary Data, 2007-2011 

Table 3 shows that the average application rate was 0.3 lbs. a.i. per acre for the top crops. 

Table 3. MCPA Use on Top Crops: Total Pounds Applied, Total Acres Treated and 

A vera~e A .. I R ate, 2007 -2011 

Crop Pounds Applied, Total Acres Treated, A vg. AI Rate (lbs. 

Annual Average Annual Average a.i./acres) 

Spring Wheat 1,500,000 5,100,000 0.3 

Winter Wheat 600,000 1,800,000 0.3 

Barley 300,000 1,000,000 0.3 

Source: EPA Proprietary Data, 2007-2011 

Geographic Distribution of MCPA USE 

Agricultural Usage by Crop Reporting District 

Another measure of usage is the use intensity. In this analysis, the use intensity is expressed as 

the pounds a.i. applied per 1 000 acres of land in farms. This differs from the application rate, 

which is expressed as the pounds a.i. applied per treated area. The average application rate of 

Page 5 
0.3 lb a.i. per acre implies a rate of 300 lbs. a.i. per I 000 treated acres. The maximum use 

intensity observed ranges from 31 lbs. to 45 lbs a.i. per 1000 acres of land in farms. Figure 2 

spatially represents MCPA usage by crop reporting district for 2007-2011. Use is widespread 

across the US, probably reflecting use on wheat which is grown in many areas. The highest use 

intensity is across the North ofthe country, reflecting a concentration of use on wheat and barley 

in the Great Plains and in Eastern Washington and Idaho. For more information on the use of 

the included map, see Appendix A. 

Page 6 
FIGURE 2. MCPA Use by Crop Reporting District (2007-2011) 

Average Pounds Per 

1,000 Acres of Farmland 

- 0-3 

- 4-9 

D 1o-1s 

- 19-30 

- 31-45 

This is a map of agricultural pesticide usage at the Crop Reporting District (CRD) level 

prepared by BEAD for use in the Environmental Fate and Effects Division documents. 

These maps are used to help visualize where the pesticide being considered is most likely 

to be used and can be helpful in scenario selection and placing the exposure assessment in 

context. CRDs are boundaries created by USDA NASS which are aggregates of counties. 

Pesticide usage is displayed as average pounds (for the years 2007-2011) per 1,000 acres of 

farmland in a CRD to normalize for the variation in farmland between CRDs. Farmland 

acreage was obtained from USDA (2007). Farmland or "land in farms" is defined as 

follows: 

The acreage designated as "land in farms" consists primarily of 

agricultural land used for crops, pasture, or grazing. It also 

includes woodland and wasteland not actually under cultivation or 

used for pasture or grazing, provided it was part of the farm 

operator's total operation. Large acreages of woodland or 

wasteland held for nonagricultural purposes were deleted from 

individual reports during the edit process. Land in farms includes 

Page 7 
CRP, WRP, FWP, and CREP1 

acres. Land in farms is an operating 

unit concept and includes land owned and operated as well as land 

rented from others. Land used rent free was reported as land rented 

from others. All grazing land, except land used under government 

permits on a per-head basis, was included as "land in farms" 

provided it was part of a farm or ranch. Land under the exclusive 

use of a grazing association was reported by the grazing 

association and included as land in farms. All land in American 

Indian reservations used for growing crops, grazing livestock, or 

the potential of grazing livestock was included as land in farms. 

Land in reservations not reported by reservation, individual 

American Indians or non-Native Americans was reported in the 

name of the cooperative group that used the land. In many 

instances, an entire American Indian reservation was reported as 

one farm (USDA, 2007). 

Usage is based on private market surveys of pesticide use in agriculture (Proprietary Data, 

2007-2011). The survey data are limited to the states that represent the top 80-90percent of 

acreage for the individual crops; therefore, use may be occurring in regions outside the 

scope of the survey. CRDs showing no usage of pesticides may be due to either the lack of 

pesticide use in the region or non-participation in the agricultural surveys. In addition, 

across the years, there may be variations in the specific crops included in the CRD survey. 

This may result in a lower annual average for the CRD. 

This map displays ratio data (i.e., average pounds per 1,000 acres of farmland) summarized 

at a very high-level. Readers are strongly cautioned against trying to over interpret the map 

without examination of the underlying data. The underlying data may explain some of the 

many reasons that a Crop Reporting District may have a high value for a particular active 

ingredient such as significant acreage (compared with the CRD as a whole) of a crop or 

crops with a high application rate and frequency of application. 

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. Scale and units of measurement do matter and may be different 

between maps. 

Non-Agricultural Usage 

The available data on MCPA use on non-agricultural sites show changes, but not in a consistent 

direction. Use ofMCPA on golf courses and institutional turf increased substantially from 2004 

to 2006 (Table 4). Combined, these two sectors show a ten-fold increase in use in only two 

years, with two-thirds of the increase in use from institutional turf. The use on landscape 

decreased drastically from 38,000 lbs. a.i. in 2002 to 2,000 lbs. a.i. in 2006. The largest use of 

1 CRP: Conservation Reserve Program; WRP: Wetland Reserve Program; FWP: Farmable Wetlands Pr~gram; CREP: Conservation Reserve Enhancement Program 

Page 8 
this chemical on grass and turf was by lawn care operators (LCOs ). This use in 2006 was less 

than half of what was used in 2002, as shown in Table 4. Most of the decline happened between 

2002 and 2004. The most recent 2011 non-agricultural use ofMCPA is 1.3 million lbs. a.i. used 

in consumer lawn herbicides, mostly in combination with other active ingredients. 

Table 4. MCP A Non-Agricultural Use 

Segment/Site 2002/lb. a.i. 

Golf Courses · NIA 

Institutional Turf NIA 

Landscape 38,000 

Lawn Care Operators (LCOs) 642,000 

Nurseries/Greenhouses N/A 

Source: Kline and Company, Inc., 2002,2004, and 2006 

Data are not available for the cells with N/A 

CHEMICAL AND USE CHARACTERISTICS 

2004/lb. a.i. 2006/lb. a.i. 

5,000 21,000 

1,000 41,000 

32,000 2,000 

276,000 283,000 

N/A <500 

MCPA herbicide controls annual and perennial broadleafweeds. According to the Weed Science 

Society of America mechanism of action classification, MCPA belongs to the Group 4 herbicides 

(family of synthetic auxins). It is a selective, post-emergent, systemic herbicide and available as 

a single active product or in mixtures. For best weed control, weeds should be sprayed when they 

are actively growing and at their most susceptible stage. For example, annuals should be sprayed 

when young and perennials just prior to appearance of bud stage. Ester formulations of MCPA 

have a higher volatility than other formulations. Therefore, at high temperatures, application of 

ester formulations can damage the sensitive non-target plants around the application site 

(Herbicide Handbook, 2003). Furthermore, the presence ofbiotypes of9 weed species with 

resistance to the group 4 herbicides has been reported in the United States. Among them prickly 

lettuce (Lactuca serriola) has shown resistance to 2,4-D, dicamba, and MCPA (International 

Survey of Herbicide Resistant Weeds, 2011 ). 

ROLE OF MCP A IN PEST MANAGEMENT 

The major role of MCPA in pest management is wide use as a postemergence herbicide for selective 

control of annual and perennial broadleaf weeds in many agricultural and non-agricultural sites. 

Although BEAD has never evaluated the benefits of MCP A, the usage data shown in Table 1 

highlights the value ofMCPA to wheat (especially spring wheat) and barley. These important 

use sites are referenced in BEAD's screening level usage analysis (SLUA) (USEPA 2013), 

which shows that up to 40 percent of the wheat crop (which includes both spring and winter 

wheat) and up to 40 percent ofthe barley crop may be treated with MCPA. The SLUA shows 

that MCP A may have an important role for smaller crops, with up to 20 percent of green peas 

treated, and up to 10 percent of oats. These shares of crop treated, however, are on smaller 

crops, so only about 8,000 pounds of MCP A were applied to green peas, and up to 100,000 on 

oats. 

Page 9 
DATA NEEDS 

The Agency currently has usage data for most ofthe agricultural crops/sites for which MCPA is 

registered. Usage data are unavailable on the small crops such as oats, rye, flax, and on nonagricultural use sites. 

BEAD has little information on use of MCP A and its importance in non-agricultural use sites. 

Obtaining the information on nonagricultural, uncultivated areas/soils and ornamental lawns and 

turf would improve future assessments conducted by the Agency related to the use and 

importance of MCP A. 

BEAD does not know why use on turf sites, such as golf courses and institutional turf have 

increased so substantively. Information on the value ofMCPA to these sectors, and any changes 

in the controlled weed spectrum and information on the herbicides that can be used as 

alternatives to MCP A would be important to determine the value of MCP A usage on turf and 

ornamental lawns. 

APPENDIX A 

The map included above 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 amount (in 

pounds) ofthe active ingredient applied per 1,000 acres of"land in farms". These data are 

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

across farmland. Because of the definition of Land in Farms, as discussed below, the calculated 

values presented in the map are not equivalent to an application rate (lbs. a.i. I a). 

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

consider the underlying data and the associated limitations carefully. 

The smallest areas shown on the maps within each state are Crop Reporting Districts (CRD). 

CRDs are defined by USDA and each consists of multiple counties that have similar soils, 

growing conditions, and farming practices. The CRDs within many states have roughly the same 

area. Because it is not feasible to conduct an agricultural survey that samples every county in the 

United States, the use of CRDs allow for a sample to be collected that represent a much larger 

area with relatively homogeneous agricultural characteristics. 

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, 2007-2011 ). 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 

Page 10 
The result of these limitations is that CRDs that show no usage may actually have a small 

amount of the active ingredient being used. 

The denominator (1 ,000 Acres ofland in farms) was selected from the Census of Agriculture 

(USDA, 2007) to represent agricultural acreage that is actively managed and includes most of the 

areas treated with pesticides. The category "Land in Farms" is defined by the Census of 

Agriculture as being made up of four components: 

• Total cropland 

• Permanent pasture 

• Total woodland 

• Land in farmsteads, buildings, livestock facilities, ponds, roads, wasteland, etc. 

This category includes land in the various USDA conservation programs. It should be noted that 

the Census of Agriculture does not include grazing land rented (on a per-animal basis) from the 

Bureau of Land Management or Forest Service, thus it is an underestimate ofthe land being 

managed for agricultural purposes. 

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. 

Scale and units of measurement do matter and may be different between maps. 

REFERENCES: 

Grube, A H. 2008. Usage Report Package in Support of Registration Review for the Herbicide 

MCPA, (03051), BEAN DP #: 352641, Decision#: 38254. 

Herbicide Handbook. 2003. Guidance on the use of herbicides on nature conservation sites, 

Sections 1-4. MCP A. Pp 91-92. http:/ /publications.naturalengland.org.uk/publication/680 19. 

Accessed on Nov. 18,2013. 

International Survey of Herbicide Resistant Weeds. 2011. 

http://www.weedscience.com/surnmary/home.aspx. Accessed on July 19,2013. 

Proprietary Data, 1998-2011. 

USDA, NASS. 2007-2010. Crop Reporting Districts. Online: 

http://www.ers.usda.gov/briefmg/arms/resourceregions/resourceregions.htm#nass. Accessed on 

July 3, 2013. 

USDA, 2007. Census of Agriculture. Online: 

http://www.agcensus.usda.gov/Publications/2007/index.asp. Accessed on July 2, 2013. 

USEP A. 2004. EPA R.E.D. Facts. MCP A. 

http://www.epa.gov/oppsrrd1/REDs/factsheets/mcpa red fs.pdf. Accessed on July 9, 2013. 

USEPA. 2013. MCPA Case (30501, 30502,30511,30516,30563, and 30564) Screening Level 

Usage Analysis (SLUA), Date: July 25, 2013. 

Page 11 
WSSA (Weed Science Society of America (WSSA), 201 1. Summary ofHerbicide Mechanism of 

Action According to the Weed Science Society of America. http://wssa.net/wpcontent/uploads/WSSA-Mechanism-of-Action.pdf. Accessed on July 17, 2013. 

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