UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MEMORANDUM 

Date: February 6, 2014 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

SUBJECT: MCPA. Human Health Risk Assessment Seeping Document in Support of 

Registration Review 

PC Code: 03050 I, 030502, 030516, 030564 

Decision No.: 483034 

Petition No.: Not Applicable 

Risk Assessment Type: Single Chemical 

TXR No.: Not Applicable 

MRID No.: None 

FROM: Alexandra LaMay, Biologist 

DP Barcode: 0414988 

Registration No.: Not Applicable 

Regulatory Action: Registration Review Scoping 

Case No.: 0017 

CAS No.: 94-74-6 

40 CFR: §180.339 

Danette Drew, Chemist -::::;.:=::::-~L....._--~--c,-r-// 

THRU: 

TO: 

Linda Taylor, Toxicologist 

Risk Assessment Branch II 

Health Effects Division (7509P) 

Office of Pesticide Progri] fj.Z-t 

Peter Savoia, Chemist U 0 /) 0 

Michael Metzger, Chief, tv{ / · 

Risk Assessment Branch I 

Health Effects Division (7509P) 

Office of Pesticide Programs 

KhueNguyen 

Pesticide Re-evaluation Division (7508P) 

Office of Pesticide Programs 

Attached is the Health Effects Division's (HED) human health seeping document for MCPA to 

support the registration review process. 

Page 1 of31 
Executive Summary 

The Health Effects Division (HED) has evaluated the status of the human health risk assessment 

for MCPA to determine the scope of work necessary to support Registration Review. The most 

recently completed human health risk assessment was considered as part of this scoping exercise. 

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

used for the control of annual and perennial broadleaf weeds. MCP A is a phenoxy herbicide 

registered for use on alfalfa, barley, clover, flax, oats, pasture and rangeland grass, peas, rye, 

triticale, and wheat, as well as grass grown for seed, to control a variety of broadleaf weeds. 

MCPA is also registered for use on turf, lawns, golf courses, and rights-of-way. 

The toxicity database for MCPA (4-(chloro-2-methyl phenoxy) acetic acid) is complete and 

adequate for characterization of potential developmental, reproductive, carcinogenetic, 

mutagenic, neurotoxic, and immunotoxic effects. New toxicity data [an inhalation toxicity study 

(870.3465) and a developmental neurotoxicity (DNT) study (870.6300))] have been received 

since the last risk assessment. During registration review of MCP A, endpoint selection, PODs, 

and UF/SFs for the dietary and inhalation risk assessments may need to be re-evaluated, based on 

new data and updated policies and procedures. 

The residue chemistry database is complete with the exception of a metabolism study on peas 

and additional residue field trial data on peas (as identified in the 2004 MCP A risk assessment). 

The current tolerance expression should be updated to comply with HED's current policy on 

tolerance expressions during registration review. 

There are currently no Codex or Canadian maximum residue limits (MRLs) established. There 

are several MRLs being proposed by Codex. Not all of the proposed MRLs would be 

harmonized with the current U.S. tolerances. HED is not currently involved in any joint 

international review projects that involve the active ingredient, MCP A 

Currently there are no acute or chronic dietary risk estimates which are of concern for MCPA 

and its metabolites. However, updated dietary exposure assessments for MCP A may be 

necessary under registration review if there are significant changes to the drinking water 

estimated concentrations which will be updated by EFED, or if there are significant changes to 

the points of departure (PoDs) or UFs/SFs. 

Previous residential handler and post-application exposure assessments did not result in risk 

estimates of concern for adults or children. An updated residential exposure and risk assessment 

may be required during registration review if warranted by any significant change in exposure 

assessment methodology, toxicological points of departure, or uncertainty factors. 

Residential bystander exposures resulting from off-site transport (i.e., spray drift or 

volatilization) may occur as a result of occupational applications of MCP A The need for a 

bystander risk assessment for MCP A will be considered during registration review. 

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Page 3 of 31

There are no current aggregate risks estimates of concern for MCPA. During registration review, 

updated aggregate assessments may be conducted as required to include any significant change 

that might occur for toxicological PODs, FQPA and uncertainty factors, dietary exposure 

estimates, residential exposure estimates, or EDWCs. A short-term aggregate assessment should 

be conducted and should include residential exposures and chronic food and drinking water. 

Based on the previous occupational exposure assessment, most of the handler exposure risk 

estimates were not of concern with single layer PPE. All of the post-application worker 

exposure risk estimates were not of concern on day 0. The WPS REI for MCPA is 12 hours for 

the ester form and 48 hours for the amine and sodium salt forms. A DFR study is required for 

MCPA at this time since some of the estimated dermal occupational post-application MOEs are 

less than 4 times the LOC. An updated occupational exposure and risk assessment may be 

required during registration review if warranted by any changes to policy or points of departure.

Impurities may be formed during the manufacturing process of the phenoxy chemicals and may 

remain in the technical product. This is a potential issue that will be addressed during 

registration review. Since the 1990s, the manufacturing processes have been modified to reduce 

concentrations of impurities in the technical products. HED will continue to monitor data on the 

impurities and reassess any potential risks as necessary.

Introduction

HED has evaluated the most recent complete human health risk assessment for MCPA to 

determine if sufficient data are available and if updates are needed to support registration review. 

HED has also considered updates to its toxicity, exposure and usage databases, and the latest

Agency science policy and risk assessment methodologies. 

MCPA is a selective, post-emergence systemic herbicide used for the control of annual and 

perennial broadleaf weeds. MCPA belongs to phenoxy or phenoxyacetic acid family. Phenoxy 

herbicides act by simulating the action of natural hormones and produce uncoordinated cell division 

and plant growth. The mechanism of action of this herbicide is by interfering with the protein

bio-synthesis which leads to uncontrolled cell division and growth; ultimately, killing the 

susceptible weeds. Products of MCPA are available in salt, ester, or amine forms. MCPA is used 

in mixture with many other products to achieve a wider spectrum of weed control. MCPA can be 

applied in various forms (free acids, esters or salts), but it releases a single common moiety that 

is the pesticidally active component and serves as the basis for tolerance regulation. The active 

ingredients (AIs) are MCPA (PC code 030501), MCPA sodium salt (PC code 030502), MCPA 

dimethylamine salt (MCPA DMAS; PC code 030516), MCPA isooctyl ester (PC code 030563), 

and MCPA 2-ethylhexyl ester (MCPA 2-EHE; PC code 030564). 

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

pastureland, peas, rye, and wheat. The registered non-agricultural use sites of MCPA include: 

nonagricultural, uncultivated areas/soils, ornamental lawns, and turf. Formulations include 

granulars, emulsifiable concentrates, and soluble concentrate/liquids.

MCPA is also a metabolite of MCPB (4-(4-chloro-2-methylphenoxy)butanoic acid), which is 

also a pesticide active ingredient. A separate scoping document will be issued for MCPB.
Page 4 of 31

Hazard Identification/Toxicology

MCPA is a member of the dichlorophenoxy class of herbicides that function by mimicking the 

action of auxins, plant growth hormones.

The toxicity database for MCPA is complete and adequate for characterization of potential 

developmental, reproductive, carcinogenetic, mutagenic, neurotoxic, and immunotoxic effects

with the submission of new data (inhalation study and DNT). The newly submitted data will 

need to be reviewed to support registration review, but no new toxicity data will be required.

In metabolism studies in rats, MCPA was rapidly absorbed and eliminated mainly in the urine

and no bioaccumulation occurred. The major urinary component is MCPA. 

The kidney and liver are the major target organs following MCPA exposure. In the subchronic 

inhalation toxicity study, which was submitted subsequent to the last risk assessment, portal-ofentry effects were observed following repeat inhalation exposure. Additional toxic effects 

include neurotoxicity, which was observed in the acute and subchronic (ACN/SCN) 

neurotoxicity studies and in a rat developmental toxicity study on the dimethylamine salt of 

MCPA. The developmental neurotoxicity study (DNT), which was submitted subsequent to the 

last risk assessment to satisfy this data requirement, did not identify developmental 

neurotoxicity. Developmental toxicity occurred in the developmental studies in rats at dose 

levels that produced maternal toxicity. Developmental toxicity was not observed in rabbits, and

reproductive toxicity was not observed in the rat. Qualitative susceptibility was observed in rats, 

as evidenced by decreased fetal body weight, altered growth, and increased litter resorptions at 

dose levels that produced less severe toxicity in the maternal rat (decreased maternal body 

weight gain). MCPA is classified as not likely to be carcinogenic to humans, based on long-term 

studies in rats and mice, and there are no mutagenicity concerns. MCPA is not acutely toxic by 

the oral, dermal, and inhalation routes of exposure, based on lethality studies; it is not a skin 

irritant but shows severe eye irritation and is negative for dermal sensitization. There is no 

concern for immunotoxicity, and the data requirement for immunotoxicity testing has been 

waived (TXR No. 0056819, dated November 5, 2013).

The acute, subchronic, and chronic toxicity profile tables for MCPA are included in Attachment 

2. Toxicity endpoints, PODs, and UF/SFs were selected for oral, dermal, and inhalation 

exposure pathways for the Human Health Risk Assessment conducted in 2004 (D299356), and 

these are presented in Attachment 3. HED notes that endpoint selection was made before receipt 

of the inhalation study and DNT. 

Conclusions: The toxicity database for MCPA is considered complete with the submission of an 

inhalation study and a DNT. HED will need to review these new studies and may need to revisit 

the endpoints, PoD, and UFs/SF used for risk assessment during registration review.

Dietary Exposure

Residue Chemistry
Page 5 of 31

The residue chemistry database is incomplete. A metabolism study on peas and additional 

residue field trial data on peas remains outstanding (see Data Requirements section).

Parent MCPA is the residue of concern for tolerance enforcement and adequate analytical 

enforcement methods exist for plant and livestock commodities. 

The chemical structure and nomenclature of MCPA is listed in Table A.1. The physicochemical 

properties of technical grade MCPA are listed in Table A.2.

Impurities may be formed during the manufacturing process of the phenoxy chemicals and may 

remain in the technical product. This is a potential issue that will be addressed during 

registration review. Since the 1990s, the manufacturing processes have been modified to reduce 

concentrations of impurities in the technical products. HED will continue to monitor data on the 

impurities and reassess any potential risks as necessary.

The following residue chemistry data requirements were identified in the September 30, 2004 

RED for MCPA. HED has updated the current status of those requirements below as some 

requirements have since been fulfilled:

 860.1300 Metabolism studies on peas 

There do not appear to be any data submissions reflecting the metabolism of MCPA on 

peas. There are adequate metabolism data for the MCPA on wheat (grain and straw) but 

peas are sufficiently different in composition than wheat that a separate metabolism study 

is required. This data requirement remains outstanding. 

 860.1340 Residue analytical method for plants 

The Residue Chemistry Chapter of the Registration Standard dated 8/31/81 noted that the 

PAM Vol I method is adequate for enforcement of tolerances for residues of MCPA in 

livestock commodities as-is, however the Agency had at that time recommended the 

method be modified with a hydrolysis step for enforcement of MCPA tolerances for plant 

commodities. The current PAM Vol II methods are adequate for the enforcement of 

MCPA on plants and livestock commodities and no further modifications are required at 

this time. The data requirement for 860.1340 residue analytical methods is fulfilled.

 860.1380 Storage stability data for wheat grain stored under ambient conditions for 28 

days 

Subsequent to the 2004 requirement, the MCPA Task Force submitted data depicting the 

stability of MCPA, 2-HMCPA and CCPA in/on wheat grain under ambient conditions to 

support the existing wheat processing study (MRIDs 47670701, 47670702, 47670703, 

47670704, and 47670705). The data have been reviewed by HED (D279942, D262444, 

and D227174, D. Davis, 10/12/10, MCPA. Review of Wheat Field Trials and Ambient 
Page 6 of 31

Storage Stability Data Submitted in Response to Reregistration Eligibility Document 

Data Requirements. The storage stability data gap has been fulfilled.

 860.1480 Ruminant feeding study

Examination of EPA’s OPPIN database indicates that a ruminant feeding study has been 

submitted (MRID 47075201; Koch, D. (2007) Magnitude of the Residue of MCPA in 

Dairy Cow Milk, Cattle Meat and Tissues. Project Number: 49737, 214/001/10. 

Unpublished study prepared by ABC Laboratories, Inc. and Genesis Midwest 

Laboratories. 279 p.). This study will be evaluated under MCPA registration review for 

acceptability and fulfillment of the feeding study requirement.

 860.1500 Four field trials reflecting a 0-day PHI for pasture forage 

The 2004 MCPA risk assessment determined that the number of available field trials for 

pasture and rangeland grass forage and hay is adequate to fulfill data requirements but 

that additional data were required reflecting a 0-day PHI for pasture grass forage.

HED has since examined the available data and determined that the existing residue data 

for MCPA reflecting a 0 day PHI for rangeland grass forage is suitable to fulfill the 

requirement for 0 day PHI data for pasture grass forage (MRID 46331602) since the use 

patterns are similar. Field trials on rangeland grass (MRID 43801301) and pasture grass 

(MRIDs 43782401 and 43791901) reflect two applications of MCPA at 2.0 lb are/A (4.0 

lb ae/A total). Field trails were performed using both the 2-EHE EC and DMAS SC. 

Samples were analyzed for the residues of MCPA, HMPCA, and CCPA. Rangeland grass 

forage was sampled at 0, 7, 21, and 30 day PHIs. Pasture grass forage was sampled at 7, 

14, 21, and 30 day PHIs. Average residues in pasture grass forage are lower than average 

residue in rangeland forage at the corresponding PHIs of 7, 21, and 30 days. Average 

residues (MCPA only, the residue for tolerance enforcement) in rangeland forage at a 0 

day PHI were 287 ppm for the DMAS formulation and 205 ppm for the 2-EHE 

formulation. The 0 day PHI results for the rangeland grass forage are sufficient to fulfill 

the 860.1500 residue data requirement for “grass, forage”. 

 860.1500 Pea field trial data

Although no data requirements were listed for pea field trials in the 2004 MCPA RED, 

the 9/14/04 supporting chemistry document, MCPA. List A Reregistration Case 0017. 

Chemical No. 030501, 030502, 030516, 030564. Revised Product and Residue 

Chemistry Chapters for the Reregistration Eligibility Decision (D307890) identified the 

following: “No data are available reflecting determination of the metabolites 2-HMCPA, 

and CCPA. The available data indicate that residues of MCPA were <0.05 ppm in or on 

peas (succulent and dry) harvested 38 days after application (using ground equipment) of 

the sodium salt at 0.37 - 0.75 lb ae/A)(1-2x the maximum rate). Data depicting residues 

of MCPA, 2-HMCPA and CCPA in or on peas (succulent and dry) harvested after 

application of representative EC and SC/L formulations of the dimethylamine salt and the 

ester are required”.
Page 7 of 31

U.S. field trial data for peas were subsequently submitted (MRID 47253101) and 

reviewed (D346715, 4/8/08, T. Goodlow, MCPA. Magnitude of Residue and Storage 

Stability Study on Peas) with the following conclusions: the data supplied are insufficient 

for the tolerance reassessment of peas. In order to support all uses on peas, five 

additional field trials including MCPA and its metabolite 2-HMCPA are required. 

Additional pea field trial data were also submitted reflecting trials in Europe (MRIDs 

46837210, 46837211, 46837212, 46837213, and 46837214). That review concluded the 

following: The magnitude of residue studies are classified as unacceptable but upgradable 

due to insufficient U.S. crop field trials. The magnitude of residue studies can be 

upgraded provided the MCPB Task Force submits justification stating why the European 

trials are analogous to U.S. growing regions for peas (D330176, 7/31/08, MCPB: Data 

Evaluation Records for Magnitude of the Residue and Storage Stability Studies for Peas 

Conducted in Europe).

The data requirement for pea field trial data remains outstanding. 

 860.1900 A study detailing confined accumulation in rotational crops planted following 

treatment at 1.5 lb ae/A 

The MCPA Task Force Three has submitted a protocol (No MRID, dated 12/5/11) for a 

confined rotational crop study to support MCPA. HED has evaluated the protocol and 

concluded that “the choice of crops, radiolabel position, and sampling procedures are 

appropriate. However, the first sampling interval is much greater than the EPA and the 

OECD guidance recommends” (D305037, 2/8/12, C. Olinger, MCPA and Salts. 

Confined Rotational Crop Study Protocol Review). This study has been completed and 

submitted to the Agency. This study will be evaluated for acceptability and fulfillment of 

the rotational crop study requirement.

Dietary Assessment

For risk assessment purposes, the residue of concern in livestock commodities is MCPA but in 

plant commodities the residues of concern include both parent MCPA and its metabolite 2-

HMCPA [(4-chloro-2-hydroxymethylphenoxy)acetic acid]. The residue considered in drinking 

water was MCPA (free acid).

The most recent dietary risk assessment for MCPA was performed in 2004 as part of the RED 

(D307891, 9/15/04, F. Fort, Revised MCPA Acute and Chronic Dietary Exposure Assessments 

for the Reregistration Eligibility Decision). Both acute and chronic dietary (food only) exposure 

assessments were performed using the Dietary Exposure Evaluation Model (DEEM-FCID, 

Version 1.30) which uses food consumption data from the USDA’s Continuing Surveys of Food 

Intakes by Individuals (CSFII) from 1994-1996 and 1998. The assessments are considered very 

conservative since tolerance level residues were assumed. For the acute assessment 100% crop 

treated (CT) was assumed. The chronic assessment incorporated estimated % CT treated values 

from BEAD. Default DEEM processing factors were used.
Page 8 of 31

The EFED provided the drinking water values for use in the 2004 dietary assessment using 

simulation models to estimate the potential concentration of MCPA in ground and surface water. 

Limited surface and ground water monitoring data are available for MCPA but these data are not 

adequate to perform a quantitative drinking water assessment. Conservative Tier II (PRZMEXAMS) modeling was used to determine that estimated drinking water concentrations 

(EDWCs) in surface water were not likely to exceed 47.3 ppb for peak (acute) exposure and 1.9 

ppb for mean (chronic) exposure. For groundwater, the SCI-GROW model EDWC is 2.13 ppb. 

Drinking water estimates were derived using a pasture/rangeland application scenario. EDWCs

were not incorporated directly into the DEEM models. Instead, a drinking water level of concern 

(DWLOC) approach was used. Under registration review EFED will re-examine the MCPA 

EDWCs using updated Tier II modeling, including the PRIZM-GW model.

Acute dietary (food) risk estimates were not of concern for MCPA (<100% aPAD). At the 95th

percentile of exposure, the acute risk estimates were 17% of the aPAD for the general U.S. 

population. The population subgroup with the highest estimated exposure was children 1-2 years 

old at 36% aPAD. 

Chronic dietary (food) risk estimates were not of concern (<100% aPAD). The chronic risk 

estimates were 3% of the aPAD for the general U.S. population. The population subgroup with 

the highest estimated exposure was children 1-2 years old at 9% aPAD. 

The recently updated % CT estimates (7/25/13 SLUA; BEAD) resulted in significant reductions 

in average %CT for most crops and modest increases for barley and green peas and would not be 

expected to have a significant impact on the dietary assessment.

The EDWCs were not incorporated directly into the dietary risk assessment DEEM model but 

were compared to calculated Drinking Water Levels of Comparison (DWLOCs). A DWLOC is 

a theoretical upper concentration limit for a pesticide in drinking water based on how much of 

the PAD remains once exposures in food have been estimated and subtracted. For MCPA, acute 

and chronic DWLOCs were calculated. Upon comparison of the chronic and acute DWLOCs 

with the EDWCs for MCPA, surface and groundwater concentrations were substantially less 

than the DWLOCs for all populations and there was no chronic or acute concern for drinking 

water from surface or groundwater sources. The resulting surface and ground water acute 

EDWCs of 47.3 ppb and 2.13 ppb were less than the calculated acute DWLOCs which ranged

from 392 ppb to 1455 ppb. Chronic EDWCs of 1.9 ppb and 2.13 for surface and groundwater 

were likewise found to be below the chronic DWLOCs and ranged from 402 to 1497 ppb.

Conclusions: Currently there are no acute or chronic dietary risk estimates which are of concern 

for MCPA and its metabolites. Updated dietary exposure assessments for MCPA may be 

necessary under registration review if the toxicological PoDs or uncertainty factors/safety factors 

(UFs/SFs) change, or there are significant changes in the EDWCs.

Residential (Non-Occupational) Exposure
Page 9 of 31

Residential Handler Exposure

MCPA is registered for use on residential lawns, ornamental turf and trees, golf courses, and 

parks. There is potential for residential handler exposure. Short-term dermal and inhalation 

exposure to MCPA while mixing, loading, and applying products may occur. ARIs for dermal 

and inhalation exposure in the previous assessment (D307892) ranged from 2.8 to 46 and are not 

of concern. Since the previous assessment in 2004, the Health Effects Division’s 2012 Standard 

Operating Procedures for Residential Pesticide Exposure Assessment has updated exposure 

assessment methodology for residential exposure scenarios, including methodology for adult 

handler exposure assessment. An updated residential handler assessment may be needed under 

registration review as a result of these revisions.

Conclusions: An updated residential handler assessment may be required under registration 

review if warranted by any significant change in exposure assessment methodology, 

toxicological points of departure, or uncertainty factors. 

Residential Post-application Exposure

There is potential for residential post-application exposure to MCPA. Dermal exposure is likely 

for adults and children entering treated lawns and playing golf or contacting treated plants; 

children may also experience incidental oral exposure during post-application activities on 

treated turf. Post-application exposure and risks for treated lawns were previously assessed for 

MCPA (D307892). The short-term ARI (combined dermal and oral exposure) for toddlers 

playing on treated lawns ranged from 2.23-2.91 and are not of concern. The short-term dermal 

MOEs for adults performing yard work and golfing ranged from 2,500 to 43,000 and are not of 

concern. These scenarios were assessed using chemical-specific turf transferable residue (TTR)

data available for MCPA (MRIDs 45033101 and 44655702). 

An acute assessment was also performed for post application exposures compared to acute points 

of departure in the 2004 assessment. Typically, post application turf exposures are considered to 

be short-term in duration and are compared to the appropriate short-term POD. The total acute 

dermal and oral MOE was 940 for toddlers playing on lawns, which is slightly less than the 

target MOE of 1000. Dermal acute MOEs for adults performing yard work and golfing on 

treated grass ranged from 2,300 to 49,000. 

Since the previous assessment, the Health Effects Division’s 2012 Standard Operating 

Procedures for Residential Pesticide Exposure Assessment has updated exposure assessment 

methodology for residential exposure scenarios, including adult and children exposure to treated 

turf and golf courses. An updated residential handler assessment may be needed under 

registration review as a result of these revisions.

Conclusions: An updated residential post-application assessment may be required under 

registration review if warranted by any significant change in exposure assessment methodology, 

toxicological points of departure, or uncertainty factors. The TTR data requirement has been 

satisfied for MCPA. There are no other data requirements for MCPA at this time.
Page 10 of 31

Residential Bystander Exposures

Residential exposures resulting from off-site transport (i.e., spray drift or volatilization) may 

occur as a result of agricultural applications of MCPA. The Agency is in the process of 

evaluating these types of exposures and may, as appropriate, develop policies and procedures to 

identify the need for and, subsequently, the way to incorporate these post-application exposures 

into the Agency's risk assessments. The need for spray drift and volatilization risk assessment 

for MCPA will be examined during Registration Review.

Aggregate Risk Assessment

In accordance with the Food Quality Protection Act (FQPA), HED must consider and aggregate 

pesticide exposures and risks from three major sources: food, drinking water, and residential 

exposures. The acute and chronic aggregate risk assessments for MCPA included food and 

drinking water only. Short-term aggregate risk assessment included food and drinking water. 

HED notes that estimated risks from any residues of MCPA resulting from the use of MCPB will 

be addressed in the MCPA human health risk assessment. 

Acute

The 2004 RED acute aggregate risk assessment addressed exposure to MCPA residues in food 

and water using the DWLOC approach described above. The resulting surface and ground water 

acute EDWCs of 47.3 ppb and 2.13 ppb were found to be substantially less than the calculated 

acute DWLOCs, ranging from 392 ppb to 1455 ppb, and are therefore not of concern. 

Chronic

Chronic DWLOCs were calculated based on chronic dietary exposures to MCPA in food and 

water since no chronic residential scenarios were identified. Chronic EDWCs of 1.9 ppb and 

2.13 for surface and groundwater were likewise found to be below the chronic DWLOCs, 

ranging from 402 to 1497 ppb, and are therefore not of concern. 

Short-term

A short-term aggregate exposure assessment combining food, water and residential exposure was 

not conducted in the 2004 RED. There was no concern for short-term residential exposures or for 

the chronic food and water exposures. In the future the short-term aggregate assessment should 

include residential exposures and chronic food and drinking water.

Conclusions: During registration review, updated aggregate assessments may be conducted as 

required to include any significant change that might occur for toxicological PODs, FQPA and 

uncertainty factors, dietary exposure estimates, residential exposure estimates, or EDWCs. A 

short-term aggregate assessment should be conducted and should include residential exposures 

and chronic food and drinking water. HED notes that estimated risks from any residues of 

MCPA resulting from the use of MCPB will be addressed in the MCPA human health risk 

assessment.
Page 11 of 31

Occupational Exposure

Occupational Handler Exposure

MCPA is registered for commercial use on lawns, ornamental turf and trees, golf courses, parks, 

roadsides, rights of way and agricultural use on alfalfa, barley, clover, flax, oats, pasture and 

rangeland grass, peas, rye, triticale, wheat and grass grown for seed. There is potential for 

occupational handler and post-application exposure. Occupational handler exposure scenarios 

include mixing/loading; applying by aerial, groundboom, spreader or handheld equipment;

mixing/loading/applying by handheld equipment; and flagging. These handler scenarios have 

been previously assessed (D307892). The assessment noted that labels typically require single 

layer personal protective equipment (PPE). Most of the mixer/loader MOEs exceeded the target 

of 100 with baseline or single layer PPE and were not of concern; the MOEs for handlers 

wearing single layer PPE ranged from 77 to 4,600. The MOE for mixing/loading liquids for 

aerial application to rangeland/pastures was acceptable with the addition of a PF5 respirator to 

single layer PPE. The MOEs for applicators were above 100 and were not of concern. The MOEs 

for the mixer/loader/applicator and flagger scenarios were acceptable with single layer PPE.

Recommended unit exposures for occupational handler assessments have generally been derived 

only from the Pesticide Handlers Exposure Database (PHED). However, recently both the 

Outdoor Residential Exposure Task Force (ORETF) and the Agricultural Handler Exposure Task 

Force (AHETF) have produced pesticide handler exposure monitoring data that the Agency is 

using in place of PHED (http://www.epa.gov/pesticides/science/handler-exposure-data.html). As 

more reliable data become available, the Agency will continue to replace existing data. 

Reviewers should incorporate new exposure monitoring data, as necessary, during registration 

review.

Conclusions: An updated occupational handler assessment may be required under registration 

review if warranted by any significant changes in exposure assessment methodology, 

toxicological PODs or uncertainty factors.

Occupational Post-application Exposure

Occupational post-application exposure to MCPA is possible for workers entering treated fields. 

An assessment was previously completed for exposure to MCPA for workers entering treated 

fields (D307892); short- and intermediate-term MOEs ranged from 250 to 10,000. Chemicalspecific TTR data were used for the assessment. Default DFR assumptions were used as 

chemical-specific DFR data are not currently available for MCPA.

Recommended transfer coefficients for occupational post-application assessments are derived 

from Agricultural Reentry Task Force (ARTF) exposure monitoring studies 

(http://www.epa.gov/pesticides/science/post-app-exposure-data.html). These transfer 

coefficients have been updated in 2012 based on a reanalysis and submission of new monitoring 

data. Reviewers should incorporate new exposure monitoring data, as necessary, during 

registration review.
Page 12 of 31

In accordance with the updated Part 158 data requirements (2007), one or more DFR studies are 

required when a pesticide has residential or occupational uses that could result in postapplication 

dermal exposure. As part of the recent revision to the Health Effects Division’s 2012 Standard 

Operating Procedures for Residential Pesticide Exposure Assessment, HED analyzed a number 

of DFR studies and selected a new default value for the fraction of the application rate available 

to be dislodged after a foliar application (FAR). This default value is 25%. Of the analyzed DFR 

studies, the maximum FAR value seen was 89% or 3.6 times higher than the default residue 

transfer value. Therefore, a calculated MOE of approximately 4 times higher than the LOC (i.e., 

an MOE > 400 if the LOC = 100) using the default dislodgable residue value would provide an 

adequate margin of safety for any potentially higher residues seen in a chemical-specific DFR 

study (Guidance for Requiring/Waiving Turf Transferrable Residue (TTR) and Dislodgeable 

Foliar Residue (DFR) Studies. 6/7/2012, Exposure Science Advisory Council). A DFR study is 

required for MCPA at this time since some of the estimated dermal occupational postapplication 

MOEs for MCPA are less than 4 times the LOC (<400).

Restricted Entry Interval (REI)

The Worker Protection Standard (WPS) Restricted Entry Interval (REI) for MCPA is 12 hours 

for the ester form and is 48 hours for the amine and sodium salt forms.

Conclusions: A chemical-specific DFR study is required under registration review.

An updated occupational post-application assessment may be required under registration review 

if warranted by any significant changes in exposure assessment methodology, toxicological 

endpoints or points of departure, or uncertainty factors.

Public Health and Pesticide Epidemiology Data

HED has evaluated the available incident data1and concludes that based on the low severity and 

relatively low frequency of incident cases reported for MCPA, there does not appear to be a 

concern at this time that would warrant further investigation. However; due to the 

disproportionate amount and severity of Weed-B-Gon Max Ready Spray (Reg No 000228-

00424-000239) incidents the Agency will evaluate this product further during the Preliminary 

Risk Assessment.

Tolerance Assessment and International Harmonization

Established U.S. tolerances are listed under 40 CFR §180.339(a)(1) and (2) and are expressed as 

follows (for both plants and livestock commodities): Tolerances are established for residues of 

the herbicide MCPA ((4-chloro-2-methylphenoxy)acetic acid) resulting from the direct 

application of MCPA or its sodium or dimethylamine salts, or its 2-ethylhexyl ester in or on the 

following food commodities. 

 

1 MCPA (2-methyl-4-chlorophenoxyacetic acid): Tier I Review of Human Incidents: S. Recore. 12/3/2013. 

D415940
Page 13 of 31

It may be noted that the current tolerance definition does not include the appropriate 

measurement statement and should not include a reference to the formulation types being 

applied. Also the reference to “direct application” is not appropriate for livestock tolerances; 

currently, there are no registered direct livestock treatments of MCPA. The correct tolerance 

expression for both plant and livestock commodities should read as follows: Tolerances are 

established for residues of the herbicide MCPA ((4-chloro-2-methylphenoxy)acetic acid), 

including its metabolites and degradates, in or on the commodities in the table below. 

Compliance with the tolerance levels is to be determined by measuring residues of MCPA ((4-

chloro-2-methylphenoxy)acetic acid), both free and conjugated, determined as the acid, in or on 

the following commodities.

There are currently no Canadian maximum residue limits (MRLs) established. There are several 

MRLs being proposed by Codex. The U.S. tolerance and Codex MRL residue definitions include 

parent MCPA only (see Attachment 4).

Generally, the U.S. tolerance levels and proposed Codex MRLs are not harmonized. Codex 

MRLs are lower for various grains and peas but are higher for straw, fodder and grasses. Codex 

MRLs are lower for livestock fat, byproducts and for milk. Livestock meat levels are 

harmonized. Codex is also proposing limits on commodities with no U.S. tolerances such as 

poultry products, eggs, maize and triticale. The differences between U.S. tolerance levels and 

Codex MRLs may be due to differences in use pattern between the U.S. and Codex countries. In 

the case of limits based on non-detectable residues, or LOQ, analytical methods with different 

LOQs may have been used. Some differences may also be attributable to older residue 

definitions, i.e. U.S. tolerances for livestock commodities were originally established based on 

the combined residues of MCPA and its metabolite 2-methyl-4-chlorophenol. Although that 

metabolite is no longer considered a residue of concern for enforcement purposes, the tolerance 

levels still reflect the inclusion of that metabolite. 

International or Intergovernmental Work Sharing

HED is not currently involved in any joint international review projects that involve the active 

ingredient, MCPA. Additionally, HED is unaware of any ongoing international assessments for 

MCPA. 

Cumulative 

The FQPA requires the Agency to consider the cumulative risks of chemicals sharing a common 

mechanism of toxicity. MCPA is a member of the alkylphenoxy herbicide class of pesticides. 

This class also includes 2,4-DB, 2,4-D and 2,4-DP. Although the various phenoxy herbicides 

have similar structural components, HED has not made a determination that they have a common 

mode of toxic action. Therefore, a cumulative risk assessment has not been performed for these 

compounds.

Human Studies 
Page 14 of 31

There are no MCPA-specific human studies that require an ethics review at this time. Previous 

HED risk assessments relied in part on data from studies in which adult human subjects were 

intentionally exposed to a pesticide or other chemical. These data, which include studies from 

PHED 1.1; the AHETF database; the ARTF database; and the ORETF database, are (1) subject 

to ethics review pursuant to 40 CFR 26, (2) have received that review, and (3) are compliant with 

applicable ethics requirements. For certain studies, the ethics review may have included review 

by the Human Studies Review Board. Descriptions of data sources, as well as guidance on their 

use, can be found at the Agency website2. 

Data Deficiencies

The following data deficiencies were identified for MCPA:

Toxicology

 None

Residue Chemistry

 860.1300 Metabolism studies on peas 

 860.1500 Pea field trial data

Occupational and Residential Exposure

 875.2100 Dislodgeable Foliar Residue (DFR) data

References

MCPA [(4-chloro-2-methylphenoxy)acetic acid]. Revised Human Health Risk Assessment for 

the Reregistration Eligibility Decision (RED) Document. Reregistration Case No. 0017. 

Chemical Nos. 030501, 030502, 030516, 030564. DP Barcode D307892. September 14, 2004. 

F. Fort.

MCPA: Second Revised Occupational and Residential Exposure and Risk Assessment for the 

Reregistration Eligibility Decision (RED) Document. DP Barcode D305056. September 7, 2004. 

T. Dole.

MCPB/MCPA: Summary of Hazard and Science Policy Council (HASPOC) Meeting of October 

24, 2013: Recommendations on the Requirement of an Immunotoxicity Study for MCPA/MCPB, 

a Subchronic Inhalation Toxicity Study for MCPB, and a Subchronic Dermal Toxicity Study for 

MCPB. TXR No. 0056819, November 5, 2013. J. Leshin. 

 

2

http://www.epa.gov/pesticides/science/handler-exposure-data.html and

http://www.epa.gov/opp00001/science/residential-exposure-sop.html
Page 15 of 31

MCPA (2-methyl-4-chlorophenoxyacetic acid): Tier I Review of Human Incidents. D415940. 

December 3, 2013. S. Recore. 
Page 16 of 31

Attachment 1. Chemical Identity and Physicochemical Properties

TABLE A.1. MCPA Nomenclature.

Compound

O

Cl

OH

CH3 O

Common name MCPA acid

Company experimental name NA

IUPAC name 4-chloro-2-methylphenoxyacetic acid

CAS name 4-chloro-2-methylphenoxyacetic acid

CAS registry number 94-74-6 (free acid)

Molecular weight 200.6

End-use product (EP) NA

Compound

O

Cl

O

CH3 O

Na

+

Common name MCPA sodium salt

Company experimental name JAN018051

IUPAC name sodium (4-chloro-2-methylphenoxy)acetate

CAS name (4-chloro-2-methylphenoxy)acetic acid, sodium salt

CAS registry number 3653-48-3

Molecular weight 222.6

End-use product (EP) 2.5 lb ae/gal SC/L (Nufarm MCPA Sodium 300 SC; 27.5% ae)

O

Cl

CH3 O

O[NH2(CH3)

2

]

Common name MCPA dimethylamine salt

IUPAC name (4-chloro-2-methylphenoxy)acetic acid, dimethylamine salt

CAS name (4-chloro-2-methylphenoxy)acetic acid, compound with N-methylmethanamine 

(1:1)

CAS registry number 2039-46-5

Molecular weight 245.7

End-use product (EP) 4 lb ae/gal SC/L (Nufarm Rhomene® MCPA Amine Herbicide SC; 42.5% ae)
Page 17 of 31

TABLE A.1. MCPA Nomenclature.

Compound

O

Cl

O

CH3 O

CH3

CH3

H3C

Common name MCPA 2-ethylhexyl ester

IUPAC name (4-chloro-2-methylphenoxy)acetic acid, 2-ethylhexyl ester

CAS name (4-chloro-2-methylphenoxy)acetic acid, 2-ethylhexyl ester

CAS registry number 29450-45-1

Molecular weight 312.5

End-use product (EP) 3.7 lb ae/gal EC (Nufarm Rhonox® MCPA Ester Herbicide EC; 44.8% ae)

TABLE A.2. Physicochemical Properties of the Technical Grade Forms of 

MCPA.

Parameter Values Reference

MCPA MCPA DMAS MCPA 2-EHE

Melting point/range 114-119 °C 111 °C 260-265 °C DP# 307890, 

F. Fort, 

9/14/04

pH approximately 3 Not available 3.46 at 19.7 °C 

Density (20°C)

1.18-1.21 g/mL 1.181 g/mL

8.9 lb/gal bulk density

(1.06 g/mL specific 

gravity)

Water solubility 

(20°C)

0.03 g/100 g

Rapidly dissociates to 

the free phenoxy acid 

moiety and dimethyl 

ammonium ion in 

water. 0.1%, w:w

Solvent solubility 

(20°C)

91.8 g/100 g acetone

50.2 g/100 g ethyl 

ether

5.5 g/100 g 

chloroform

3.3 g/100 g benzene Not available

Miscible in most organic 

solvents and mineral oils.

Vapor pressure 

(20°C) 7.7 x 10-6 mbar Not available 1.77 x 10-5 mbar

Dissociation 

constant, pKa 3.07 Not available Not available

Octanol/water 

partition coefficient, 

Log(KOW) 2.73 1.415 -5.37
Page 18 of 31

TABLE A.2. Physicochemical Properties of the Technical Grade Forms of 

MCPA.

Parameter Values Reference

MCPA MCPA DMAS MCPA 2-EHE

UV/visible 

absorption spectrum

Not available Not available

Absorbance peaks 

observed at 203, 228, and 

279 nm for a solution of 

MCPA 2-EHE in water 

with methanol co-solvent; 

molar absorption 

coefficient of 16784 M

-

1

cm-1

MAX 203.1 nm.
Page 19 of 31

Attachment 2. Acute, Subchronic, and Chronic Toxicity Profile

The acute toxicity data on the MCPA, MCPA DMA, MCPA EHE, and MCPA sodium salt are 

summarized in Table A-1 below.

Table A2-1. Acute Toxicity Profile - MCPA Technical, EHE, Amine, Sodium salt.

Guideline 

No. Study Type MRID Results Toxicity Category

870.1100 Acute oral [rat] MCPA acid 00021972 LD50=1.4 g/kg III

870.1100 Acute oral [rat] MCPA EHE 00156458 LD50= 2.2 mg/kg III

870.1100 Acute oral [rat] MCPA Amine 00256980 LD50=1.9 g/kg III

870.1100 Acute oral [rat] MCPA Na salt 00256979 LD50= 3.5 g/kg III

870.1200 Acute dermal [rabbit] MCPA acid 00250090 LD50 > 2000 mg/kg IV

870.1200 Acute dermal [rabbit] MCPA EHE 00156459 LD50 > 2000 mg/kg IV

870.1200 Acute dermal [rabbit] MCPA Amine 00256980 LD50 > 2000 mg/kg IV

870.1200 Acute dermal [rabbit] MCPA Na salt 00256979 LD50 > 2000 mg/kg IV

870.1300 Acute inhalation [rat] 40053101 LC50 > 6.3 mg/LAIV

870.1300 Acute inhalation [rat] 00156460 LC50 > 3.1 mg/LAIV

870.1300 Acute inhalation [rat] 42113103 LC50 > 1.7 mg/L III

870.1300 Acute inhalation [rat] 00256979 LC50 > 1.7 mg/L III

870.2400 Acute eye irritation [rabbit] 00250090 Corneal opacity and conjuctival 

irritation

I

870.2400 Acute eye irritation [rabbit] 00115522 No evidence of eye irritation IV

870.2400 Acute eye irritation [rabbit] 00248567 Corneal opacity I

870.2400 Acute eye irritation [rabbit] 00256979 Corneal opacity, stippling, 

puckering, alopecia

II

870.2500 Acute dermal irritation [rabbit] 00250090 Non-irritating IV

870.2500 Acute dermal irritation [rabbit] 00156456 Non-irritating IV

870.2500 Acute dermal irritation [rabbit] 00256980 Slight dermal irritation III

870.2500 Acute dermal irritation [rabbit] 00256979 Non-irritating IV

870.2600 Skin sensitization [Guinea Pig] 43062806 Not a skin sensitizer IV

870.2600 Skin sensitization [Guinea Pig] 40352001 Skin sensitizer IV

870.2600 Skin sensitization [Guinea Pig] 40352101 Not a skin sensitizer IV

870.2600 Skin sensitization [Guinea Pig] 41613003 Not a skin sensitizer IV

A

4-hour
Page 20 of 31

Table A-2-2a. Subchronic and Chronic Toxicity Profile – MCPA acid

Guideline No./ Study 

Type

MRID No. (year)/ Classification /Doses Results

870.3100

90-Day oral toxicity in 

rats with MCPA

MRID 00165471 (1985)

Acceptable/guideline

0, 50, 150, or 450 ppm (equivalent to 0, 3.6, 10.9, 

or 32.6 mg/kg/day for males and 0, 4.0, 12.1, or 

35.8 mg/kg/day for females). 

NOAEL = 10.9 mg/kg/day

LOAEL = 32.6 mg/kg/day based on increased 

absolute and relative kidney weights, increased 

clotting time, increased creatinine levels, and 

presence of crystaluria (oxalate, calcium 

phosphate, and urate). 

870.3150

90-Day oral toxicity in 

dogs with MCPA

MRID 00106595 (1980)

Acceptable/guideline

main study

technical MCPA

0, 77-86, 300-342, or 1198- 1370 ppm 

(equivalent to 0, 3.0, 12.0, or 48.0 mg/kg/d).

 

second study 

technical MCPA

0, 7.5, 25.0, and 300.0 ppm (equivalent to 0, 

0.3, 1.0, or 12.0 mg/kg/d) 

purified MCPA–

300.0 ppm (equivalent to 12.0 mg/kg/d)

NOAEL = 1 mg/kg/day 

LOAEL = 3 mg/kg/day, based on impaired renal 

function, without histopathological change. 

870.3200

21-day dermal-rabbit 

with MCPA

42715001 (1992)

acceptable/guideline

10, 100, or 1000 mg/kg/day

Systemic toxicity

NOAEL = 100 mg/kg/day 

LOAEL = 1000 mg/kg/day (limit dose) based 

on kidney findings (increase in incidence of 

mineralization in renal tubule) and the decrease 

in body weight gain

Dermal toxicity

NOAEL = 10 mg/kg/day

LOAEL = 100 mg/kg/day based erythema, 

desquamation, and diffuse acanthosis

870.3465

28-day inhalation 

toxicity in rats with 

MCPA

48606401 (2011)

Acceptable/non-guideline*

0, 0.05, 0.2 and 1.0 mg/L for 6 hours per day; 

reduced to 0, 0.02, 0.1 and 0.5 mg/L following 3 

(females) or 4 (males) exposures due to severe 

toxicity

*non-guideline status is because the MMAD for 

the test atmospheres especially for the mid and 

high dose exposures did not have a sufficient 

percentage of particles less than the

recommended 3 microns. Since the study did not 

demonstrate a NOAEL for alterations in the upper 

respiratory tract and because of the several 

responses to treatment, the issue of unacceptable 

particle size has added importance. 

LOAEC = 0.02 mg/L/day (both sexes), based on 

epithelial alteration in the larynx and clinical 

signs at portal of entry

NOAEC not established for portal of entry 

effects 

Systemic LOAEL = 0.1 mg/L. At the mid and 

high dose levels there was squamous cell 

metaplasia of the larynx and in the nasal cavity, 

diffuse tubular degeneration of the testes, 

increase of oligospermia and debris in the 

epididymides, and follicular hypertrophy/ 

hyperplasia of the thyroid gland and increased 

absolute/relative thyroid weight, deceased 

absolute and relative thymus weight in females, 

and decreased absolute (both sexes) and relative 

(females) spleen weight, alterations in RBC and 

WBC elements, increased prothrombin time and 

altered clinical chemistry parameters (glucose 

and urea). There were reductions in rearing in 

both sexes and lower motor activity (in 

females). Systemic NOAEC level was 0.02 

mg/L. 
Page 21 of 31

Table A-2-2a. Subchronic and Chronic Toxicity Profile – MCPA acid

Guideline No./ Study 

Type

MRID No. (year)/ Classification /Doses Results

870.3700a

Prenatal 

developmental in rats 

with MCPA

42723801 (1993)

acceptable/guideline

15, 60, and 120 mg/kg/day.

maternal toxicity

NOAEL = 60 mg/kg/day

LOAEL = 120 mg/kg/day based on decreases in 

body weight gain and food consumption during 

treatment

developmental toxicity

NOAEL = 60 mg/kg/day. 

LOAEL = 120 mg/kg/day based on decreased 

placental and fetal body weights and an increase 

in the number of fetuses with skeletal 

retardation

870.3700b

Prenatal 

developmental in 

rabbits with MCPA

42723802 (1993)

acceptable/guideline

15, 30, and 60 mg/kg/day. 

maternal toxicity 

NOAEL = 30 mg/kg/day. 

LOAEL = 60 mg/kg/day based on decreases in 

body weight and food consumption during the 

treatment period

developmental toxicity 

NOAEL > 60 mg/kg/day (HDT) 

LOAEL = not a developmental toxicant

870.3800

Reproduction and 

fertility effects in rats 

with MCPA

40041701 (1986)

acceptable/guideline

0, 50, 150, or 450 ppm (equivalent to 0, 2.5, 7.5, 

and 22.5 mg/kg/day, respectively, for both sexes 

based on 1 ppm = 0.05 mg/kg/day). 

Parental systemic toxicity

NOAEL =7.5 mg/kg/day

LOAEL =22.5 mg/kg/day based on increased 

absolute and relative ovary weights (p<0.05; 

23-25% greater than controls)

Offspring toxicity

NOAEL =7.5 mg/kg/day

LOAEL =22.5 mg/kg/day based on decreased 

pup weight gain during lactation

Reproductive toxicity

NOAEL =22.5 mg/kg/day

LOAEL = no LOAEL was established.

870.4.300

Chronic toxicity and 

carcinogenicity in rats 

with MCPA

40634101 (1988)

acceptable/guideline

0, 20, 80, or 320 ppm for 2 years 

(0, 1.1, 4.4, or 17.6 mg/kg/day in males and 1.4, 

5.7, or 23 mg/kg/day in females)

NOAEL = 4.4 mg/kg/day

LOAEL= 17.6 mg/kg/day based on 

hepatotoxicity (increased SGPT levels in 

females) and nephrotoxicity (increased urea 

nitrogen in females) were observed. In addition, 

there was an increase in the retraction and 

granular surface of the kidney associated with 

an increase in the chronic progressive 

nephropathy in the males. 

At the doses tested, there was not a treatment 

related increase in tumor incidence when 

compared to controls. Dosing was considered 

adequate.

870.4100b

Chronic toxicity dogs 

with MCPA

00164352 (1986)

acceptable/guideline

0, 6, 30, 150 ppm (0, 0.2, 1.02, or 5.32 mg/kg/day 

for males and 0, 0.21, 1.02 or 5.12 mg/kg/day for 

females)

NOAEL = 0.2 mg/kg/day

LOAEL= 1.02 mg/kg/day based on 

hepatotoxicity (increased SGPT, SGOT, 

triglycerides and cholesterol levels with 

histopathology changes) and nephrotoxicity 
Page 22 of 31

Table A-2-2a. Subchronic and Chronic Toxicity Profile – MCPA acid

Guideline No./ Study 

Type

MRID No. (year)/ Classification /Doses Results

[increased urea nitrogen, potassium, and 

creatinine levels with histopathology changes 

(increased pigmentation of the proximal tubular 

epithelium) in kidneys]. 

870.4300

Chronic toxicity and 

carcinogenicity in 

mice with MCPA 

40792301 (1988)

acceptable/guideline

0, 20, 100, or 500 ppm (0, 3.2, 15.7, or 79.5 in 

males and 0, 3.9, 19.5, or 97.2 mg/kg/day) for 2 

years.

Males:

NOAEL = 15.7 mg/kg/day

LOAEL= 79.5 mg/kg/day based on 

histopathology changes in kidneys 

Females: 

NOAEL = 3.9 mg/kg/day

LOAEL= 19.5 mg/kg/day based on renal 

hyperplasia

At the doses tested, there was not a treatment 

related increase in tumor incidence when 

compared to controls. Dosing was considered 

adequate.

870.6200a

Acute oral 

neurotoxicity in rats 

with MCPA

43562602 (1994)

Acceptable/guideline

0, 200, 400, or 800 mg/kg (males)

0, 150, 300, or 600 mg/kg (females) via gavage.

LOAEL = 400 mg/kg, based primarily on gait 

impairment in male rats 

NOAEL = 200 mg/kg.

870.6200b

Subchronic oral 

neurotoxicity in rats 

with MCPA 

43562601 (1994)

acceptable/guideline

0, 50, 500, and 2500 ppm (equivalent to 0, 3, 34, 

or 177 mg/kg/day for males and 0, 4, 42, or 188 

mg/kg/day for females).

NOAEL = 34 mg/kg/day

LOAEL= 177 mg/kg/day based on based on 

decreased body weight and body weight gains, 

liver pathology, changes in clinical chemistry 

and hematological parameters, testicular 

atrophy, reduced values of forelimb grip 

strength (day 50 only) and reduced values in the 

foot splay test (day 22 only) in males and 

reduced values of hindlimb grip strength in 

females. 

Gene mutation

870.5265

42840403 (1993)

acceptable

Salmonella typhimurium strains TA98, TA100, 

TA1535, TA1537, TA1538

Tested up to 5,000 μg/plate

The test was negative.

870.5300

Gene mutation–

Chinese hamster 

ovary cells 

(CHO/HGPRT)

42860103 (1993)

Acceptable

The test was negative.

870.5915

In Vivo Mammalian 

Cytogenetics - Sister 

Chromatid Exchange 

assay 

00148720 (1985)

acceptable

Dose: 1200 mg/kg

The test was weakly positive.

870.5385 

In Vivo Mammalian 

Cytogenetics -

Chromosomal 

aberration

40027501 (1986)

acceptable

0, 33, 200 or 1200 mg/kg body weight. 

The test was negative.
Page 23 of 31

Table A-2-2a. Subchronic and Chronic Toxicity Profile – MCPA acid

Guideline No./ Study 

Type

MRID No. (year)/ Classification /Doses Results

870.5375

cytogenetic assay 

(human lymphocytes) 

42853504 (1993)

acceptable

S9-activated doses of 1200-2000 ug/mL (13 hr 

cell harvest) that approached the solubility limit. 

The test was positive. The non-activated test 

material was cytotoxic (>500 ug/mL-21 hr cell 

harvest), but not clastogenic. 

870.7600

Dermal absorption in 

rats

46327601 (2003)

Acceptable/guideline

0.09 mg/cm2and 7.5 mg/cm2

Over all recovery was good ranging from 

90.35% to 95.46% for the low dose and 94.43% 

to 96.85 % for the high dose. For the low dose 

the majority of absorbed dose was excreted in 

the urine with the second highest portion in the 

carcass. For the high dose the absorbed test 

compound build up in the carcass with the 

highest portion at 10 hours (22.08%). At 96 

hours 12.86% remained in the carcass and 

12.28% was excreted in the urine. This pattern 

indicates saturation of excretion at the high 

dose.

870.7600

Dermal penetration

in vitro

human and rat

45897010 (2002) No review located.

Table A-2-2b. Subchronic and Chronic Toxicity Profile – MCPA DMA

Guideline No./ Study 

Type

MRID No. (year)/ Classification /Doses Results

870.3150

90-Day oral toxicity in 

dogs with MCPADMA

43556802 (1995)

Acceptable/guideline

20, 80, and 360 ppm (equivalent in the males to 

0, 0.6, 2.4 and 10.9 mg/kg/day and in the females 

to 0, 0.7, 2.9, and 12.8 mg/kg/day)

NOAEL = 0.6 MCPA-DMA (0.4 as MCPA 

acid) mg/kg/day. 

LOAEL = 2.4 MCPA-DMA (2.0 as MCPA 

acid) mg/kg/day, based on changes in 

histopathology (increases in subacute to chronic 

interstitial inflammation of liver), hematology, 

and clinical chemistry (BUN, creatinine, ALT, 

partial thromboplastin times) 

870.3200

21-day dermal-rat with 

MCPA DMA

43556902 (1995)

acceptable/guideline

12, 120, or 1000 mg/kg/day

Systemic toxicity

NOAEL =not observed at 1000 mg/kg/day 

(limit dose)

LOAEL = not observed at 1000 mg/kg/day 

(limit dose)

Dermal toxicity

NOAEL = 120 mg/kg/day

LOAEL = 1000 mg/kg/day

870.3700a

Prenatal 

developmental in rats 

with MCPA DMA 

44954102 (1999)

acceptable/guideline

0, 15, 50, or 150 mg MCPA free acid kg/day (0, 

18.5, 62 and 185 mg/kg/day MCPA-DMA)

maternal toxicity

NOAEL = 50 mg/kg/day

LOAEL = 150 mg/kg/day based on mortality 

and clinical signs (rocking, lurching, or 

swaying, hunched appearance, dried yellow 

matting/staining on the urogenital area)

developmental toxicity
Page 24 of 31

Table A-2-2b. Subchronic and Chronic Toxicity Profile – MCPA DMA

Guideline No./ Study 

Type

MRID No. (year)/ Classification /Doses Results

NOAEL = 50 mg/kg/day. 

LOAEL = 150 mg/kg/day based on increased 

resorptions, decreased fetal body weight, and 

external and skeletal malformations/variations

870.6200a

Acute oral 

neurotoxicity in rats 

with MCPA-DMA salt

43562702 (1994)

Acceptable/guideline

0, 175, 350, or 700 MCPA-DMA salt mg/kg 

(equivalent to 0, 142, 285, or 569 MCPA free 

acid mg/kg)

LOAEL = 175 mg/kg (equivalent to 142 MCPA 

Acid mg/kg) (LDT) seen in female rats based on 

ataxia. 

NOAEL could not be established.

870.6200b

Subchronic oral 

neurotoxicity in rats 

with MCPA-DMA

43562701 (1994)

acceptable/guideline

0, 60, 600, or 3,000 ppm (equivalent to 0/0, 4/5, 

42/48, or 208/232 MCPA-DMA mg/kg/day 

[M/F]; 0/0, 3.2/4.1, 34/39, or 169/189 MCPA acid 

mg/kg/day).

NOAEL = 34 mg/kg/day 

LOAEL= 169 mg/kg/day based on decreased 

body weight and body weight gains, liver 

pathology, testicular atrophy, and changes in 

clinical chemistry (ALT, AST, ALP, creatinine), 

hematological parameters and neurotoxicity 

(decreased forelimb grip strength).

870.5265

Gene Mutation -

bacterial

42624401 (1992)

acceptable

Salmonella typhimurium strains TA98, TA100, 

TA1535, and TA1537 Concentrations at 1, 4, 16, 

64, or 256 μg/plate in the presence or absence of 

S9-activation.

The test was negative.

870.5300

Gene mutation–

Chinese hamster 

ovary cells 

(CHO/HGPRT)

42860101 (1993)

Acceptable

The test was negative.

870.5375

cytogenetic assay 

(human lymphocytes)

42853505 (1993)

acceptable

Dose range: S9-activated doses of 250, 1000, or 

2000 ug/mL (13 hr cell harvest) that approached 

the solubility limit. 

The test was positive. 

The non-activated test material was not 

clastogenic. 

870.5395

Micronucleus assay

42853502 (1993)

acceptable

144, 288, or 576 mg/kg/day. 

The test was negative.

870.7600

Dermal absorption in 

rats

44193901 (1996)

Acceptable/guideline

DMA: 0.02, 0.19, 0.97, 4.66 mg acid 

equivalents/cm2

DMA: dermal penetration was 0.35%, 1.05%, 

2.79%, and 5.04% (with increasing dose) of the 

administered dose following 10-hr exposures 

and 1.01%, 3.42%, 6.02%, and 13.24%, 

respectively following a 24-hour exposure

Table A-2-2c. Subchronic and Chronic Toxicity Profile – MCPA EHE

Guideline No./ Study 

Type

MRID No. (year)/ Classification /Doses Results

870.3150

90-Day oral toxicity in 

dogs with MCPA-EHE

43556801 (1995)

Acceptable/guideline

0, 20, 80, and 360 ppm (equivalent in the males 

NOAEL = 0.6 MCPA-EHE (0.4 as MCPA acid) 

mg/kg/day. 

LOAEL = 2.5 MCPA-EHE (1.6as MCPA acid) 

mg/kg/day based on changes in clinical 
Page 25 of 31

Table A-2-2c. Subchronic and Chronic Toxicity Profile – MCPA EHE

Guideline No./ Study 

Type

MRID No. (year)/ Classification /Doses Results

to 0, 0.6, 2.5 and 11.1 mg/kg/day and in the 

females to 0, 0.7, 2.8, and 12.7 mg/kg/day as 

MCPA-EHE) (equivalent in males to 0, 0.4, 1.6, 

and 7.1 m/k/d and in females to 0, 0.4, 1.8, and 

8.1 m/k/d as MCPA acid)

chemistry parameters (increased creatinine, 

urea, and alanine aminotransferase) 

870.3700a

Prenatal 

developmental in rats 

with MCPA EHE 

44954101 (1999)

acceptable/guideline

0, 15, 40, and 120 mg MCPA free acid kg/day (0, 

23.5, 62.7, and 188.0 mg MCPA-EHE/kg/day)

maternal toxicity

NOAEL = 40 mg/kg/day

LOAEL = 120 mg/kg/day based on reduced and 

body weight gains

developmental toxicity

NOAEL = 40 mg/kg/day. 

LOAEL = 120 mg/kg/day based on total litter 

resorptions, decreased fetal weight, and altered 

growth

870.6200a

Acute oral 

neurotoxicity in rats 

with MCPA-EHE

43556702 (1994)

Acceptable/guideline*

0, 250, 500, or 1000 mg/kg

all clinical sings were reversible by day 14 post 

exposure; therefore, although the study failed to 

identify a NOAEL, the study is considered 

acceptable and the LOAEL for clinical findings is 

useful for acute reference dose consideration for 

future risk assessment.

LOAEL = 250 mg/kg (LDT) for male and 

female rats, based on FOB effects (alterations in 

gait and activity). 

NOAEL was not identified.

At higher doses (500 mg/kg for male rats and 

1000 mg/kg for female rats) decrease in body 

weight gain was observed.

870.6200b

Subchronic oral 

neurotoxicity in rats 

with MCPA-EHE

43556701 (1994)

acceptable/guideline

0, 75, 750, or 3750 ppm (equivalent to 0/0, 5/6, 

54/63, or 261/296 MCPA EHE mg/kg/day [M/F]; 

0/0, 3.2/3.8, 34.6/40.4, or 167/190 MCPA Acid 

mg/kg/day). 

NOAEL = 3.2 mg/kg/day

LOAEL= 34.6 mg/kg/day based on focal 

testicular atrophy, increased relative kidney 

weight and decreased motor activity in males 

870.5265

Gene mutation

MCPA-EHE

42870001 (1993)

acceptable

Salmonella typhimurium strains TA98, TA100, 

TA1535, TA1537, TA1538

Tested up to 5,000 μg/plate

The test was negative.

870.5300

Gene mutation–

Chinese hamster 

ovary cells 

(CHO/HGPRT)

MCPA-EHE

42860102 (1993)

Acceptable

The test was negative.

870.5375

cytogenetic assay 

(human lymphocytes) 

MCPA-EHE 

42853506 (1993)

Acceptable

The test was negative.

870.6300

Developmental 

neurotoxicity in rats

48606401 (2010)

Acceptable/guideline

0, 300, 900, or 1800 ppm during gestation 

No evidence of developmental neurotoxicity 

Maternal LOAEL = 1800 ppm (156 mg/kg/day), 
Page 26 of 31

Table A-2-2c. Subchronic and Chronic Toxicity Profile – MCPA EHE

Guideline No./ Study 

Type

MRID No. (year)/ Classification /Doses Results

MCPA-EHE 0, 200, 600, or 1200 ppm during lactation 

(equivalent to 28, 83, and 156 mg/kg/day, 

gestation/lactation) from gestation day (GD) 6 

through lactation day (LD) 21.

based on decreases in body weight, body weight 

gain, and food consumption. 

Maternal NOAEL = 900 ppm (83 mg/kg/day).

Offspring LOAEL = 1800 ppm (156 

mg/kg/day), based on decreases in body weight 

and body weight gain and an increase in pup 

mortality. 

Offspring NOAEL = 900 ppm (83 mg/kg/day).

870.7600

Dermal absorption in 

rats

MCPA-EHE

44193901 (1996)

Acceptable/guideline

EHE: 0.19 mg acid equivalents/cm2

EHE: dermal penetration was 10.69% of 

administered dose following a 24-hour exposure
Page 27 of 31

Toxicology Data Requirements

The toxicology data requirements (40 CFR 158.340) for the food uses of MCPA are presented below. Use of the 

new guideline numbers does not imply that the new (1998) guideline protocols were used.

Study

Technical

Required Satisfied

870.1100 Acute Oral Toxicity.......................................................

870.1200 Acute Dermal Toxicity ..................................................

870.1300 Acute Inhalation Toxicity..............................................

870.2400 Primary Eye Irritation....................................................

870.2500 Primary Dermal Irritation ..............................................

870.2600 Dermal Sensitization......................................................

Yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

870.3100 Oral Subchronic (rodent)...............................................

870.3150 Oral Subchronic (nonrodent) .........................................

870.3200 21-Day Dermal ..............................................................

870.3250 90-Day Dermal ..............................................................

870.3465 90-Day Inhalation..........................................................

Yes

yes

yes

no

yes

yes

yes

yes

no

yes

870.3700a Developmental Toxicity (rodent)...................................

870.3700b Developmental Toxicity (nonrodent).............................

870.3800 Reproduction .................................................................

Yes

yes

yes

yes

yes

yes

870.4100a Chronic Toxicity (rodent) ..............................................

870.4100b Chronic Toxicity (nonrodent)........................................

870.4200a Oncogenicity (rat)..........................................................

870.4200b Oncogenicity (mouse)....................................................

870.4300 Chronic/Oncogenicity....................................................

Yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

870.5100 Mutagenicity—Gene Mutation – bacterial ....................

870.5375 Mutagenicity—Structural Chromosomal Aberrations...

870.5550 Mutagenicity—Other Genotoxic Effects.......................

Yes

yes

yes

yes

yes

yes

870.6100a Acute Delayed Neurotoxicity (hen)...............................

870.6100b 90-Day Neurotoxicity (hen)...........................................

870.6200a Acute Neurotoxicity Screening Battery (rat) .................

870.6200b 90-Day Neurotoxicity Screening Battery (rat)...............

870.6300 Developmental Neurotoxicity........................................

No

no

yes

yes

CR

-

-

yes

yes

yes

870.7485 General Metabolism ......................................................

870.7600 Dermal Penetration ........................................................

870.7800 Immunotoxicity .............................................................

Yes

CR

Yes

yes

yes

-

A

 AHASPOC waived this requirement (TXR No. 0056819, dated 11/05/13)
Page 28 of 31

Attachment 3. MCPA Toxicological Doses and Endpoints for Risk Assessment

Table A3.1 Summary of Toxicological Doses and Endpoints for MCPA for Use in Dietary and NonOccupational Human Health Risk Assessments

Exposure/ 

Scenario

Point of 

Departure

Uncertainty/FQPA 

Safety Factors

RfD, PAD, 

Level of 

Concern for 

Risk 

Assessment

Study and Toxicological Effects

Acute Dietary 

(General 

Population,

including 

Infants and 

Children)

NOAEL= 

50

mg/kg/day

UFA= 10x

UFH= 10x

FQPA SF= 1x

UFDB = 10x

Acute RfD = 

0.05

mg/kg/day

aPAD = 0.05

mg/kg/day

Developmental toxicity study (rats)

MCPA DMA 

Maternal toxicity LOAEL = 150 

mg/kg/day (as acid equivalent) based on 

clinical signs of neurotoxicity.

Acute Dietary

(Females 13-

49 years of 

age)

NOAEL =

40 

mg/kg/day

UFA= 10x

UFH= 10x

FQPA SF= 1x

UFDB = 10x

Acute RfD = 

0.04

mg/kg/day

aPAD = 0.04

mg/kg/day

Developmental toxicity study (rats)

MCPA-2-EHE

LOAEL = 120 mg/kg/day (as acid 

equivalent) based on total litter 

resorptions.

Chronic 

Dietary (All 

Populations)

NOAEL= 

4.4 

mg/kg/day

UFA= 10x

UFH= 10x

FQPA SF= 1x

UFDB = 10x

Chronic RfD 

= 0044

mg/kg/day

cPAD = 

0.0044

mg/kg/day

Chronic toxicity/carcinogenicity study 

(rats)

MCPA acid

LOAEL = 17.6 mg/kg/day based on

hepatotoxicity and nephrotoxicity at 17.6 

mg/kg/day.

Incidental Oral 

Short-and 

IntermediateTerm

NOAEL= 

4.4

mg/kg/day

UFA= 10x

UFH= 10x

FQPA SF= 1x

UFDB = 10x

Residential 

LOC for 

MOE = 1000

Subchronic neurotoxicity and chronic 

toxicity studies in rats based on 

neurotoxicity, renal, and testicular 

toxicities.a

Dermal 

(Short-and 

IntermediateTerm)

Dermal 

NOAEL= 

100 

mg/kg/day

UFA= 10x

UFH= 10x

FQPA SF= 1x

UFDB = 10x

Residential 

LOC for 

MOE = 1000

21-day dermal toxicity study (rabbits)

LOAEL = 1000 mg/kg/day based on 

nephrotoxicity and the decrease in body 

weight gain.

Dermal (LongTerm)

NOAEL=

4.4

mg/kg/day

UFA= 10x

UFH= 10x

FQPA SF= 1x

UFDB = 10x

Dermal absorption 

factor = 7%

Residential 

LOC for 

MOE = 1000

Chronic toxicity/carcinogenicity study 

(rats)

LOAEL = 17.6 mg/kg/day based on

hepatotoxicity and nephrotoxicity at 17.6 

mg/kg/day.

Inhalation (All 

durations)

NOAEL=

4.4

mg/kg/day

UFA= 10x

UFH= 10x

FQPA SF= 1x

UFDB = 10x

Inhalation 

absorption factor = 

100%

Residential 

LOC for 

MOE = 1000

Chronic toxicity/carcinogenicity study 

(rats)

LOAEL = 17.6 mg/kg/day based on

hepatotoxicity and nephrotoxicity at 17.6 

mg/kg/day.

Cancer (oral, 

dermal, 

inhalation)

Classification: Not likely to be carcinogenic to humans
Page 29 of 31

Point of Departure (PoD) = A data point or an estimated point that is derived from observed dose-response data and used to mark 

the beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures. NOAEL = no 

observed adverse effect level. LOAEL = lowest observed adverse effect level. UF = uncertainty factor. UFA = extrapolation 

from animal to human (interspecies). UFH = potential variation in sensitivity among members of the human population 

(intraspecies). UFL = use of a LOAEL to extrapolate a NOAEL. FQPA SF = FQPA Safety Factor. PAD = population adjusted 

dose (a = acute, c = chronic). RfD = reference dose. MOE = margin of exposure, LOC = level of concern, NA = Not Applicable 

* NOTE: The Special FQPA Safety Factor recommended by the HIARC assumes that the exposure databases (dietary food, 

drinking water, and residential) are complete and that the risk assessment for each potential exposure scenario includes all 

metabolites and/or degradates of concern and does not underestimate the potential risk for infants and children.

a = The HIARC selected the dose of 4.4 mg/kg/day for short and intermediate term incidental oral exposure risk 

assessments based on the similarity of toxicity seen in the subchronic neurotoxicity studies in rats with the acid, DMA 

and EHE forms, as well as the toxicity seen following chronic exposure in rats with the acid. 

Table A3.2 Summary of Toxicological Doses and Endpoints for MCPA for Use in Occupational Human 

Health Risk Assessments

Exposure/ 

Scenario

Point of 

Departure

Uncertainty 

Factors

Level of Concern 

for Risk 

Assessment

Study and Toxicological Effects

Dermal (Shortand 

IntermediateTerm)

Dermal 

NOAEL= 

100 

mg/kg/day

UFA= 10x

UFH= 10x

Occupational LOC 

for MOE = 100

21-day dermal toxicity study (rabbits)

LOAEL = 1000 mg/kg/day based on 

nephrotoxicity and the decrease in body 

weight gain.

Dermal (LongTerm 

NOAEL=

4.4

mg/kg/day

UFA=10x

UFH=10x

Dermal 

absorption 

factor = 7%

Occupational LOC 

for MOE = 100

Chronic toxicity/carcinogenicity study 

(rats)

LOAEL = 17.6 mg/kg/day based on

hepatotoxicity and nephrotoxicity at 17.6 

mg/kg/day.

Inhalation (All 

Durations)

NOAEL=

4.4

mg/kg/day

UFA=10x

UFH=10x

Inhalation 

absorption 

factor = 100%

Occupational LOC 

for MOE = 100

Chronic toxicity/carcinogenicity study 

(rats)

LOAEL = 17.6 mg/kg/day based on

hepatotoxicity and nephrotoxicity at 17.6 

mg/kg/day.

Cancer (oral, 

dermal, 

inhalation)

Classification: Classification: Not likely to be carcinogenic to humans

Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and used to 

mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures. NOAEL 

= no observed adverse effect level. LOAEL = lowest observed adverse effect level. UF = uncertainty factor. UFA = 

extrapolation from animal to human (interspecies). UFH = potential variation in sensitivity among members of the human 

population (intraspecies). MOE = margin of exposure. LOC = level of concern. N/A = not applicable.
Page 30 of 31

Attachment 4. International Residue Limits

MCPA (PC030501; 11/7/13)

Summary of US and International Tolerances and Maximum Residue Limits 

Residue Definition:

US Canada Mexico1 Codex2, 3

40 CFR 180.

Plant: (a) General. (1) MCPA ((4-chloro-2-

methylphenoxy)acetic acid), both free and 

conjugated, resulting from the direct 

application of MCPA or its sodium or 

dimethylamine salts, or its 2-ethylhexyl ester 

None MCPA

Commodity Tolerance (ppm) /Maximum Residue Limit (mg/kg)

US Canada Mexico1 Codex2, 3

Alfalfa, forage 0.5

Alfalfa, hay 2.0

Barley, grain 1.0 0.2

Barley, hay 40

Barley, straw 25 50 barley straw and fodder, dry

Clover, forage 0.5

Clover, hay 2.0

Flax, seed 0.1 0.01 (*)

Grain, aspirated fractions 3.0

Grass, forage 300

Grass, hay 20 500 hay or fodder (dry) of grasses

Lespedeza, forage 0.5

Lespedeza, hay 2.0

Oat, forage 20

Oat, grain 1.0 0.2

Oat, hay 115

Oat, straw 25 50 oat straw and fodder, dry

Pea, dry 0.1 0.01 (*)

Pea, field, hay 0.1

Pea, succulent 0.1

Pea, field, vines 0.1

Rye, forage 20

Rye, grain 1.0 0.2

Rye, straw 25 50 rye straw and fodder, dry

Trefoil, forage 0.5

Trefoil, hay 2.0

Vetch, forage 0.5

Vetch, hay 2.0

Wheat, forage 20

Wheat, grain 1.0 0.2

Wheat, hay 115

Wheat, straw 25 50 wheat straw and fodder, dry

40 CFR 180.

Livestock: (2) MCPA ((4-chloro-2-

methylphenoxy)acetic acid) resulting from 

the direct application of MCPA or its sodium 

or dimethylamine salts, or its 2-ethylhexyl 

ester

MCPA

The residue is not fat soluble.

Commodity Tolerance (ppm) /Maximum Residue Limit (mg/kg)

US Canada Mexico1 Codex2, 3
Page 31 of 31

Summary of US and International Tolerances and Maximum Residue Limits 

Residue Definition:

US Canada Mexico1 Codex2, 3

Cattle, fat 0.1 0.2 mammalian fats (except milk 

fats) 5

Cattle, meat 0.1 0.1 meat (from mammals other than 

marine mammals)

Cattle, meat byproducts 0.1 3 edible offal (mammalian)

Goat, fat 0.1 0.2 mammalian fats (except milk 

fats) 5

Goat, meat 0.1 0.1 meat (from mammals other than 

marine mammals)

Goat, meat byproducts 0.1 3 edible offal (mammalian)

Hog, fat 0.1 0.2 mammalian fats (except milk 

fats) 5

Hog, meat 0.1 0.1 meat (from mammals other than 

marine mammals)

Hog, meat byproducts 0.1 3 edible offal (mammalian)

Horse, fat 0.1 0.2 mammalian fats (except milk 

fats) 5

Horse, meat 0.1 0.1 meat (from mammals other than 

marine mammals)

Horse, meat byproducts 0.1 3 edible offal (mammalian)

Milk 0.1 0.04 

Sheep, fat 0.1 0.2 mammalian fats (except milk 

fats) 5

Sheep, meat 0.1 0.1 meat (from mammals other than 

marine mammals)

Sheep, meat byproducts 0.1 3 edible offal (mammalian)

MRLs with NO US Equivalent

Eggs 0.05 (*)

Maize 0.01 (*)

Maize fodder (dry) 0.34

Poultry, fats 0.05 (*)

Poultry, meat 0.05 (*)

Poultry, edible offal of 0.05 (*)

Triticale 0.2

Triticale straw and fodder, dry 50

Completed: M. Negussie; 11/14/13

1 Mexico adopts U.S. tolerances and/or Codex MRLs for its export purposes.

2

* = absent at the limit of quantitation; Po = postharvest treatment, such as treatment of stored grains. PoP = 

processed postharvest treated commodity, such as processing of treated stored wheat. (fat) = to be measured on the 

fat portion of the sample. MRLs indicated as proposed have not been finalized by the CCPR and the CAC.

3 All tolerances are proposed

4 Annex I to JMPR 2012 includes “straw”. Codex code AS 0645 only refers to “fodder”. Clarification from the 

secretariat may be needed. 

5 Annex I to JMPR 2012 indicates only Mammalian fats. Codex code MF 0100 excludes milk fats. Clarification 

from the secretariat may be needed.