, 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

MEMORANDUM 

Date: December 3, 2013 

SUBJECT: MCPA (2-methyl-4-chlorophenoxyacetic acid): Tier I Review of Human 

Incidents 

PCCode:030501,030502,030516,030563,030564 

Decision No.: 483034 

Petition No.: NA 

DP Barcode: D415940 

Registration No.: NA 

Regulatory Action: NA 

Risk Assessment Type: NA CaseNo.:NA 

TXRNo.:NA CAS No.: 94-74-6,3653-48-3,2039-46-5,26544-20-7, 

29450-45-1 

MRIDNo.:NA 

FROM: 

THROUGH: 

TO: 

40CFR:NA 

Shanna Recore, Industrial Hygienist 

Toxicology and Epidemiology Branch 

Health Effect Division (7509P) 

and 

Elizabeth Evans, Environmental Protection Specialist 

Toxicology and Epidemiology Branch 

Health Effects Division (7509P) /\ 

: I ~- j j}J /7/ 

David Miller, Acting Branch ChieVv~J / //r£1/v'i , Toxicology and Epidemiology Branch 

Health Effects Division (7509P) 

Alexandra LaMay, Risk Assessor 

Risk Assessment Branch VII 

Health Effects Division (7509P) 

and 

K. Nguyen, Chemical Review Manager 

Risk Management & Implementation Branch 1 

Pesticide Re-evaluation Division (7508P) 

Summary and Conclusions 

Ver.Apr.08 

Based on the low severity and relatively low frequency of incident cases reported for MCPA (2-

methyl-4-chlorophenoxyacetic acid), there does not appear to be a concern at this time that 

would warrant further investigation. However; due to the disproportionate amount and severity 

Page 1 of5 
ofWeed-B-Gon Max Ready Spray (Reg No 000228-00424-000239) incidents the Agency will 

evaluate this product further during in the Preliminary Risk Assessment. 

Detailed Review 

I. ACTION REQUESTED 

This review is intended to fulfill our requirement to docket summaries of incident data that were 

reported to the Agency, as well as to ensure human incident data and the Agricultural Health 

Study (AHS) are part of the problem formulation phase of registration review. Reports of 

adverse health effects allegedly due to a specific pesticide exposure (i.e., an "incident") are 

largely self-reported and therefore, generally speaking, neither exposure to a pesticide or 

reported symptom (or the connection between the two) is validated or otherwise confirmed. 

Typically, causation cannot be determined based on incident data. However, incident 

information can be an important source of feedback to the Agency: incidents of severe outcome, 

or a suggested pattern or trend among less severe incidents, can signal the Agency to further 

investigate a particular chemical or product. Observational epidemiology studies relate the risk 

of disease, e.g., cancer, and exposure to an agent such as a pesticide product in the general 

population or specific sub-groups like pesticide applicators. 

II. BACKGROUND 

MCPA is an herbicide in the phenoxy or phenoxyacetic acid family that is used post-emergence 

for selective control ofbroadleafweeds. MCPA is registered for use on alfalfa, barley, clover, 

flax, lespedeza, oats, pasture and rangeland grass, peas, rye, trefoil, triticale, and wheat, as well 

as grass grown for s.eed, to control a wide spectrum of broadleaf weeds. MCP A is also registered 

for use on turf, lawns, vines, rights-of-way, and forestry applications. Residential homeowners 

may use MCPA on lawns. 1 

For this evaluation, both the OPP Incident Data System (IDS) and the Centers for Disease 

Control and Prevention/National Institute for Occupational Safety and Health (CDC/NIOSH) 

Sentinel Event Notification System for Occupational Risk-Pesticides (SENSOR) databases were 

consulted for pesticide incident data on the active ingredient MCPA (PC codes: 030501, 030502, 

030516, 030563, 030564). The purpose of the database search is to identify potential patterns in 

the frequency and severity of the health effects attributed to MCP A exposure. MCP A is not 

included in the AHS, and therefore this study does not provide information for this report. 

III. RESULTS/DISCUSSION 

a. IDS (Incident Data System) 

OPP's IDS includes reports of alleged human health incidents from various sources, including 

mandatory Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) Section 6(a)(2) reports 

from registrants, other federal and state health and environmental agencies, and individual 

1 Excerpt from MCPA Factsheet, found online at: 

http://www .epa. gov/ oppsrrd 1/REDs/factsheets/mcpa red fs. pdf 

Page 2 of5 

' 
consumers. Since 1992, OPP has compiled these reports in IDS. IDS contains reports from 

across the U.S. and most incidents have all relevant product information recorded. Reports 

submitted to the IDS represent anecdotal reports or allegations only, unless otherwise stated in 

the report. 

IDS records incidents in one of two modules: Main IDS and Aggregate IDS: 

o Main IDS contains incidents resulting in higher severity outcomes and provides 

more detail with regard to case specifics. This system stores incident data for 

death, major and moderate incidents, and it includes information about the 

location, date and nature of the incident. Main IDS incidents involving only one 

active ingredient (as opposed to pesticide products with multiple active 

ingredients) are considered to provide more certain information about the 

potential effects of exposure from the pesticide. 

o Aggregate IDS contains incidents resulting in less severe human incidents (minor, 

unknown, or no effects outcomes). These are reported by registrants only as 

counts in what are aggregate summaries. 

For the Main IDS, from January 1, 2008 to September 11, 2013, there were 0 incidents reported 

for single chemical only in the database. There were 69 incident reported involving more than 

one chemical? Two incidents were classified as major severity; however, upon further review 

these incidents could not be directly linked to the product used (Table 1 ). The other 67 incidents 

were classified as moderate severity. 

In Aggregate IDS, from January 1, 2008 to September 11, 2013, there were 324 reported 

incidents involving MCP A. Six incidents were classified as unknown or no effects and 318 

incidents were classified as minor severity. 

Weed-B-Gon Max Ready Spray (Reg No 000228-00424-000239) appears to be implicated in a 

large number of incidents in both Aggregate (83%) and Main IDS (97%). This product is used on 

residential lawns for weed control. In addition to MCPA (13.72%), this product contains the 

active ingredients Triclopyr (1.56%) and Dicamba (1.35%). This may be potentially attributable 

to the high use of this product by consumers as reported in private market research studies and 

the Agency will consider this possibility to the extent possible in future assessments. It should 

be noted that this product also appeared to have higher severity incidents than other comparable 

MCPA containing products. 

2 There were also six incidents that occurred in Canada, 9 in England, 4 in Germany and 1 in Ireland. Foreign 

incidents are not reviewed in detail because of the potential differences in the exposure patterns, use practices, and 

product formulation. 

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T a bl e 1 M . am IDS M . a,] or In ct 'd ens t D escnp11ons 'f £ or MCPA 

Human Incident Chemical: MCPA PC Codes: 030501, 030502, 030516, 030563, 

030564 

.~ •' Ic • .. 'd _i ,lr '•: ~· 

Incident Exposure .. 

Package Incident Reg Severity 

RePOrt Date Location Number Product Name Codes Incident Description 

A 63 year old male has used this product 

every year for a few years on the lawn. 

The product sometimes gets on him and 

WEED-B-GON Major he rinses it off. He has experienced 

000228- MAX READY urinary urgency, weight loss, and muscle 

023382 00424- SPRAY 32 FL weakness. He has been to MDs, who 

-00030 9/112011 NJ 000239 oz cannot determine the cause. 

An unknown age male used the product 

outside. He did not wear a mask and he 

developed pain in his lungs. He was 

WEED-B-GON Major hospitalized the next day and diagnosed 

000228- MAX READY with Multiple Myeloma and blood clots 

024580 00424- SPRAY32 FL in his lungs. The MD does not believe it 

- 00019 9/13/2012 ME 000239 oz is related to the product. 

b. SENSOR-Pesticides 

The SENSOR-Pesticides database covers 11 states from 1998-2009, although reporting varies 

from state to state. Cases of pesticide-related illnesses are ascertained from a variety of sources, 

including: reports from local Poison Control Centers, state Department of Labor workers' 

compensation claims when reported by physicians, reports from State Departments of 

Agriculture, and physician reports to state Departments of Health. Although both occupational 

and non-occupational incidents are included in the database, SENSOR-Pesticides focuses on 

occupational pesticide incidents, and is of particular value in providing that information. The 

state coordinator at each of the 11 respective state Departments of Health conducts case followup activities such as obtaining medical records to verify symptoms and severity. Using 

standardized protocol and case definitions derived from poison center reporting, the state 

SENSOR-Pesticide coordinator enters the incident information into the state-based system which 

is sent to NIOSH annually to be aggregated. 

A query of SENSOR-Pesticides 1998-2009 finds 47 cases involving MCPA. Six cases involve a 

single active ingredient and 41 cases involve multiple active ingredients. Of the six single active 

ingredients cases, two were moderate in severity and four were low in severity. Case symptoms 

are provided in Table 2. 

Table 2. SENSOR-Pesticides 1998-2009: Reported 

Health Effects for MCPA Cases 

Health Effect # of Times Re rted 

Page 4 of5 
Dermal 3 

Ocular 3 

Respiratory 2 

Gastrointestinal 3 

Renal 0 

Nervous System 4 

Cardiovascular 0 

Miscellaneous 2 

* Cases may report multiple health effects 

The first moderate severity case occurred in Washington State in 2002, the case is described as 

follows, "Three teachers at Whittier Elementary School had symptoms after a strong herbicide 

odor entered the school ventilation system. The odor was from Superfund clean-up of chemical 

manufacturing wastes buried in a nearby landfill. Air sampling data at site monitors detected 

MCPP. Reported student symptoms were not documented." 

This is also the case description for a low severity incident from the same event. Presumably 

only two of the three teachers mentioned experienced symptoms because there are only two 

SENSOR case reports. 

The second moderate severity case occurred in Texas in 1998 and is described as follows, "Farm 

hand/licensed applicator, applying pesticides for several years. He did not use protective 

equipment; developed symptoms." 

c. Agricultural Health Study (AHS) 

The AHS is a high quality, prospective epidemiology study evaluating the link between pesticide 

use and various health outcomes including cancer. The AHS includes private and commercial 

pesticide applicators and their spouses. If there are AHS findings relevant to a particular 

pesticide going through registration review, the Agency will ensure they are considered in the 

problem formulation/scoping phase of the process and, if appropriate, fully reviewed in the risk 

assessment phase of the process. The AHS includes information on use of 50 different pesticide 

active ingredients commonly used in agriculture. MCP A is not included in the AHS, and 

therefore this study does not provide information for this report. 

IV. CONCLUSION 

Based on the low severity and relatively low frequency of incident cases reported for MCP A in 

both IDS and SENSOR-Pesticides, 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 in the Preliminary Risk Assessment. 

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