Monosodium methylarsonate
Last updated: 19/01/2023
(Also known as: arsanote Liquid; MSMA; agent purple; monosodium methanarsonate)
Monosodium methylarsonate is a herbicide that is not widely approved for use in the developed world due to its toxicity. As well as being highly toxic it is also a known skin, eye and inhalation irritant. It is highly soluble in water and considerd to be persistent in soils. Monosodium methylarsonate is moderately toxic to fish, algae and honeybees and slightly less toxic to birds.
The following alerts are based on the data in the tables below. An absence of an alert does not imply the substance has no implications for human health, biodiversity or the environment but just that we do not have the data to form a judgement.
Environmental fate
Ecotoxicity
Human health
 
A non-food herbicide applied post-emergence and used to control weeds mostly in non-food areas
Grassy weeds; Sedges; Broad-leaved weeds
Cotton; Turf grass
-
Current
-
Not approved
Not applicable
No UK approval for use
EC Regulation 1107/2009 (repealing 91/414)
Not approved
Not applicable
Not applicable
Not applicable
No
ATAustria
BEBelgium
BGBulgaria
CYCyprus
CZCzech Republic
DEGermany
DKDenmark
EEEstonia
ELGreece
 
 
 
 
 
 
 
 
 
ESSpain
FIFinland
FRFrance
HRCroatia
HUHungary
IEIreland
ITItaly
LTLithuania
LULuxembourg
 
 
 
 
 
 
 
 
 
LVLatvia
MTMalta
NLNetherlands
PLPoland
PTPortugal
RORomania
SESweden
SISlovenia
SKSlovakia
 
 
 
 
 
 
 
 
 
None
CH₄AsNaO₃
C[As](=O)(O)[O-].[Na+]
-
JITOKQVGRJSHHA-UHFFFAOYSA-M
InChI=1S/CH5AsO3.Na/c1-2(3,4)5;/h1H3,(H2,3,4,5);/q;+1/p-1
Yes
Herbicide
Organometal compound; Arsenical herbicide
-
-
Synthetic
Selective, contact herbicide, phytotoxic
2163-80-6
218-495-9
286
013803
23664719
No data found
161.95
-
sodium hydrogen methylarsonate
monosodium methylarsonate
-
-
Not known
Not known
Not applicable
Not applicable
-
Technical form is a pale yellow liquid
580000
Q3 Q = Miscellaneous internet resources 3 = Unverified data of known source
High
-
-
-
-
-
-
-
-
-
-
-
-
-
-
7.94 X 10-04
Calculated
-
-3.1
Low
-
-
-
-
-
-
-
-
-
9.02
Q3 Q = Miscellaneous internet resources 3 = Unverified data of known source
-
Weak acid
-
-
-
-
-
-
-
-
-
-
-
-
-
200
Persistent
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Arsenic is environmentally stable
2.54
R3 R = Peer reviewed scientific publications 3 = Unverified data of known source
-
Peanut leaves, n=1
-
-
-
-
Stable
Stable
-
Stable
Stable
-
-
-
-
-
-
-
Soil adsorption and mobility
-
-
-
Cannot be calculated
-
-
-
-
-
-
-
-
-
Low risk
Q3 Q = Miscellaneous internet resources 3 = Unverified data of known source
Based on LogP < 3
Low risk
-
-
None
Terrestrial ecotoxicology
2449
Rat
Low
-
-
-
-
-
-
-
-
3269
Colinus virginianus
Low
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
24.0
Moderate
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
100.0
Oncorhynchus mykiss
Moderate
-
-
-
58.0
Daphnia magna
Moderate
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
93.0
Lemna gibba
Low
1.8
Pseudokirchneriella subcapitata
Moderate
-
-
-
-
-
-
-
-
-
HUMAN HEALTH AND PROTECTION
High (class III)
-
-
2449
Rat
Low
2000
Rabbit
-
2.2
Rat
-
-
-
-
-
-
-
0.1
(USA)
-
-
-
-
-
-
-
-
-
-
-
-
-
Potential exposures to individuals in residential settings from residues on treated lawns
Occupational handlers can be exposed via mixing, loading and application
EU MRL pesticide database 
-
-
-
-
-
-
-
-
-
-
Carcinogen
Endocrine disruptor
XNo, known not to cause a problem
A0 A = Chromosome aberration (EFSA database) 0 = No data
; B0 B = DNA damage/repair (EFSA database) 0 = No data
; C0 C = Gene mutation (EFSA database) 0 = No data
; D0 D = Genome mutation (EFSA database) 0 = No data
; E0 E = Unspecified genotoxicity type (miscellaneous data source) 0 = No data
No data found
Reproduction / development effects
Acetyl cholinesterase inhibitor
Neurotoxicant
No data found
XNo, known not to cause a problem
XNo, known not to cause a problem
Respiratory tract irritant
Skin irritant
Skin sensitiser
✓Yes, known to cause a problem
✓Yes, known to cause a problem
No data found
Eye irritant
Phototoxicant
 
✓Yes, known to cause a problem
No data found
 
Harmful if swallowed or inhaled Liver and kidney toxicant Inorganic arsenic is a known carcinogen
No information available
-
III (Slightly hazardous)
-
-
monosodium methylarsonate
methylarsonate de sodium
Natriummethylarsonat
-
-
metilarsonato de sodio
-
-
-
-
-
Record last updated:
19/01/2023
Contact:
aeru@herts.ac.uk
Please cite as:
Lewis, K.A., Tzilivakis, J., Warner, D. and Green, A. (2016) An international database for pesticide risk assessments and management. Human and Ecological Risk Assessment: An International Journal , 22 (4), 1050-1064. DOI: 10.1080/10807039.2015.1133242