Page 3 of 8

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

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 

pesticide 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, 2007 to September 13, 2012, there were 10 incidents reported 

for single chemical only in the database and 17 additional incidents reported involving more than 

one chemical. These incidents all occurred to adult homeowner applicators. They experienced 

respiratory, dermal, ocular, and neurological symptoms. These incidents were classified as 

moderate severity and are described further in Table 1. Overall, there are few incidents 

involving metheanearsonic acid, salts reported to IDS. 

In Aggregate IDS, from January 1, 2007 to September 13, 2012, there were 122 reported

incidents involving metheanearsonic acid, salts. 

b. NIOSH SENSOR

The NIOSH-led SENSOR-Pesticides database covers 11 states from 1998-2008, 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. A state SENSOR contact specialist attempts to follow-up with cases and obtains 

medical records to verify symptoms, circumstances surrounding the exposure, severity, and 

outcome. Using standardized protocol and case definitions, derived from poison center 

reporting, SENSOR-Pesticides coordinators at State Departments of Health enter the incident 

interview description provided by the case, medical report, physician into the data system. In 

order to be included in the database, all SENSOR-Pesticides cases, including low severity cases, 

must have at least two adverse health effects.
Page 4 of 8

In SENSOR-Pesticides from 1998-2008, 29 individual cases, stemming from 26 events, were 

identified. Methanearsonic acid was the single AI implicated in 17 of these cases. Three cases 

of the 29 cases are classified as high severity, six are moderate in severity and 20 are low in 

severity. Eight cases are classified as work-related and a review of narrative and details affirms 

all were occupational, resulting from pesticide applications. Table 2 provides a summary of 

symptoms reported for all cases. Cases may report multiple symptoms.

Table 2. Reported Symptom by Cases Exposed to Metheanearsonic acid, salts

MSMA was the product implicated in two (of three) high severity incidents. One high severity 

incident involved what the physician suspected to be a potentially malicious poisoning by a 

certified pesticide applicator. Descriptions for the three high severity incidents are provided in 

the Table 3 below.

Nine cases involved children (ranging from ages 2 through 17) with symptomatic exposures. In 

one multiple exposure event that occurred in Florida in 2006, four school children (11-12 years 

old) were playing in a park and all laid in grass that was stained blue from an MSMA (EPA reg # 

00060303511) application.1 All four children experienced dizziness and weakness. Two of the 

children also experienced shortness of breath and sore throats. Three of these four children were 

treated at an ER and one did not seek medical treatment. Three of these four cases were low in 

severity and one case was moderate.

Another exposure event involved two 11-year-old school children who both sat in an area at 

school that had been sprayed with Acme Crabgrass and Nutgrass Killer (single active ingredient) 

on the previous day. These two cases went to the ER and both reported headache and dizziness 

and are classified as low in severity. 

Another case involved a two-year old that sprayed Herbicide 3D RTU (contains multiple active 

ingredients) on his face, lips and in his eye. This was a low severity case. Another child case 

occurred when the 9-year-old drank from a glass he thought contained water but was actually 

Weed Be Gone. This case went to the ER and reported vomiting, nausea, and diarrhea; this case

is classified as moderate in severity. In another case involved a 15-year-old who rolled in grass 

that was sprayed with Image Herbicide and developed hives and itching and was seen by a 

physician. This case was low in severity. The final child case involved a 17-year-old but no 

narrative or details were provided for this case that was lost to follow-up. 

 

1 OPPIN query of registration # 603-3511 shows this product was cancelled in 1987. 

System Effected Number of Cases

Nervous System 16

Gastrointestinal 13

Eye 6

Respiratory 9

Dermal 9

Cardiovascular 1

Renal 1

Misc. 5
Page 5 of 8

c. 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. 

Metheanearsonic acid, salts are not included in the AHS, and therefore this study does not 

provide information for this report.

IV. CONCLUSION

Based on the low frequency and mostly low severity of incident cases reported for 

metheanearsonic acid, salts in both IDS and NIOSH SENSOR, there does not appear to be a 

concern at this time that would warrant further investigation. However; because there were three 

incidents in NIOSH SENSOR classified as high severity, the Agency will continue to monitor 

the incident information and if a concern is triggered, additional analysis will be included in the 

risk assessment.
Page 6 of 8

Table 1: IDS Incidents involving the single chemical Metheanearsonic acid, salts 

Human Incident Chemical: Metheanearsonic acid, salts PC Codes: 035301, 035302, 035303, 128920

Incident 

Package 

Report

Incident 

Date Location

Reg 

Number Product Name

Ingredient 

Name

Exposure 

Severity* Incident Description

018507 -

00042 4/16/2007

SLAINSVILLE, 

WV

000239-

02572

WEED-B-GON 

CRABGRASS 

KILLER 

(READY-TO-USE 

TRIGGER 

SPRAY)

MSMA, 

calcium salt HC

An adult male applied the product. He 

developed a sore throat that persisted for 

two weeks. He saw his MD who diagnosed 

a pollen allergy and prescribed 

antihistamine.

018818 -

00006 6/27/2007

SACRAMENTO, 

CA

000239-

02510

WEED-B-GON 

CRABGRASS 

KILLER 

CONCENTRATE

MSMA, 

calcium salt HC

An 81 year old male applied the product to 

his lawn. He did not shower after use. 

Approximately 24 post exposure he 

developed a rash on his entire body. He 

self treated with anti-itch cream. He saw 

his MD, they prescribed itch cream and 

Benadryl. Approximately 3 weeks post 

exposure; the rash has cleared on his arms 

and legs, but is persisting on his chest and 

back.

018818 -

00054 7/24/2007

INDIANAPOLIS, 

IN

000239-

02510

WEED-B-GON 

CRABGRASS 

KILLER 

CONCENTRATE

MSMA, 

calcium salt HC

An adult used the product and got some in 

their eye. The experienced a visual 

problem. No further information available.

018915 -

00038 8/21/2007 SAN JOSE, CA

000239-

02510

WEED-B-GON 

CRABGRASS 

KILLER 

CONCENTRATE

MSMA, 

calcium salt HC

A 68 year old male applied the product to 

his lawn. He believes the product misted 

back onto him during use. He used the 

product for 20 minutes and continued to 

work outside for 2 hours. Within 1.5-2 

hours after product application, he 

developed slurred speech, loss of balance 

and pain in his neck and back. The next 

morning his symptoms had resolved.

019025 -

00014 9/8/2007 NJ

000239-

02510

WEED-B-GON 

CRABGRASS 

MSMA, 

calcium salt HC

An unknown age adult male applied the 

diluted product to his lawn. Two days 
Page 7 of 8

Incident 

Package 

Report

Incident 

Date Location

Reg 

Number Product Name

Ingredient 

Name

Exposure 

Severity* Incident Description

KILLER 

CONCENTRATE

later, he developed a rash on his arms, 

fingers, and back. The rash resolved after 

about 1 week. He used hydrocortisone 

cream.

019910 -

00486 6/24/2008 VA

000239-

02510

WEED-B-GON 

CRABGRASS 

KILLER 

CONCENTRATE

MSMA, 

calcium salt HC

An unknown age adult male applied the 

product. After application his legs became 

itchy. The next day he developed a rash. 

He saw his MD who prescribed oral 

steroids. He did not take the steroids and 

his rash healed after about 1 week.

020705 -

00039 3/8/2009 MANTECA, CA

000239-

02510

WEED-B-GON 

CRABGRASS 

KILLER 

CONCENTRATE

MSMA, 

calcium salt HC

A 71 year old male used the product and 

did not wash his hands before he ate his 

lunch. He experienced severe vertigo, 

double vision and weakness.

021916 -

00043 4/28/2010 NC

000239-

02510

WEED-B-GON 

CRABGRASS 

KILLER 

CONCENTRATE

MSMA, 

calcium salt HC

An unknown age adult male used the 

product. About 6 hours later he developed 

hives from his chest to his legs and he 

experienced a tingly tongue and tightness 

in his throat. His hands also appeared to be 

swelling. He had no previous allergies.

022251 -

00001 8/11/2010 AL

019713-

00040-

073342

IMAGE 

HERBICIDE 

CRABGRASS 

CONCENTRATE 

24 FL OZ

MSMA 

(and salts) HC

An unknown age adult male used this 

product for 3 years. He has elevated arsenic 

levels in his blood. 

024179 -

00066 5/31/2012 PA

000239-

02510

WEED-B-GON 

CRABGRASS 

KILLER 

CONCENTRATE

MSMA, 

calcium salt HC

An unknown age adult male used the 

product and got some on his finger which 

may have gotten in his mouth when he 

smoked a cigarette. He experienced a 

swollen tongue. He was taken to the ER 

and given an injection of antihistamine and 

steroids. He had no response so he was 

given something stronger. He recovered 

one hour later. 
Page 8 of 8

*HC-Human Moderate (if the person alleged or exhibited symptoms more pronounced, more prolonged or of a more systemic nature than minor symptoms; and involved some form of treatment, 

even though symptoms were not life threatening and the person returned to his/her pre-exposure state of health with no additional residual disability)

Table 3: SENSOR-Pesticide High Severity Incidents involving Metheanearsonic acid, salts 

SENSOR-Pesticides 

Incidents

Chemical: Metheanearsonic

acid, salts PC Codes: 035301, 035302, 035303, 128920

Incident 

Year Location Registration Number Product Name

Exposure 

Severity* Incident Description

2007 Texas Not provided Not provided 

High

Case was spraying a customer’s yard, spray rig had a 

leak and product got on her hands & face. She reported 

dermal, ocular and gastrointestinal symptoms. 

2003 Texas 01082700039 MSMA

High

Ex told case he applied Chlordane and MSMA 8/31/03. 

Case got very sick, remains sick. She also experienced

Chloracne. Ex was a licensed applicator. Doctors 

suspect poisoning by ingestion. The case continues to 

experience Chloracne and bouts of fatigue (11/05). The 

case reported facial outbreaks from outset. She also 

reported dermal and gastrointestinal symptoms.

2006 Texas 06271900182 MSMA

High

Sprayed lawn with MSMA & Grazon P+D after work. 

Following the application the case felt bad. The next 

night he felt worse and went to the ER. He reported 

dermal, nervous system, respiratory and gastrointestinal 

symptoms. Previous diagnosed with post concussion 

syndrome suffered from fall 1 year earlier.

*SENSOR-Pesticides Severity Index

1 Fatal Death resulting from exposures to one or more pesticides

2 High Severe or life-threatening; involves treatment; commonly hospitalization to prevent death and/or loss 

of time >5 days for regular work or normal activities. Signs/symptoms may include coma, cardiac 

arrest, renal failure and respiratory depression.

3 Moderate Less severe illness/injury often involving systemic manifestations. Treatment is generally provided. 

Individual is able to return to normal functioning without any residual disability. ≥3-5 days lost 

work/normal activity 

4 Low Skin, eye, upper respiratory irritation. May also include fever, headache, fatigue or dizziness. 

Typically the illness/injury resolves without treatment. Minimal lost time (>3 days) from 

work/normal activities