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Maleic hydrazide sodium
Last updated: 23/01/2023
(Also known as: maleic hydrazide monosodium salt)
SUMMARY
Data alerts

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
 
Ecotoxicity
Moderate alert:
Fish chronic ecotoxicity: Moderate
Warning:
Significant data are missing
Human health
High alert:
Neurotoxicant
GENERAL INFORMATION
Description
A plant growth regulator used to suppress growth and to induce dormancy in some crops
Example pests controlled
Growth; Suckers; Sprout suppression
Example applications
Lawns; Amenity turf; Non-cropped areas; Fruit including citrus; Potatoes; Carrots; Onions, shallots & garlic; Tobacco; Ornamental shrubs
Efficacy & activity
-
Availability status
Current
Introduction & key dates
after 1950
UK regulatory status
UK COPR regulatory status
Approved
Date COPR inclusion expires
31/10.2032
UK LERAP status
None
EC Regulation 1107/2009 (repealing 91/414)
EC Regulation 1107/2009 status
Approved
Dossier rapporteur/co-rapporteur
Denmark/Belgium
Date EC 1107/2009 inclusion expires
31/10/2032
EU Candidate for substitution (CfS)
No
Listed in EU database
Yes as hydrazide acid
Approved for use (✓) under EC 1107/2009; by Mutual Recognition of Authorisation; and/or national regulations in the following EEA countries
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
      ✓ ✓   ✓   ✓
ISIceland
NONorway
                 
Additional information
Also used in
Australia, USA
Chemical structure
Isomerism
Isomeric
Chemical formula
C₄H₃N₂NaO₂
Canonical SMILES
C(=CC(=O)[O-])C(=O)NN.[Na+]
Isomeric SMILES
C(=C\C(=O)[O-])\C(=O)NN.[Na+]
International Chemical Identifier key (InChIKey)
TZWQQLVMMAZOTJ-UHFFFAOYSA-M
International Chemical Identifier (InChI)
InChI=1S/C4H4N2O2.Na/c7-3-1-2-4(8)6-5-3;/h1-2H,(H,5,7)(H,6,8);/q;+1/p-1
2D structure diagram/image available?
Yes
Cambridge Crystallographic Data Centre diagrams
Common Name Relationship Link
maleic hydrazide Parent
General status
Pesticide type
Plant Growth Regulator, Herbicide
Substance groups
Pyridazine PGR
Minimum active substance purity
-
Known relevant impurities
-
Substance origin
Synthetic
Mode of action
Suppresses sprout and bud growth, absorbed by leaves and roots and translocated. Enhances chlorophyll production.
CAS RN
28330-26-9
EC number
248-972-7
CIPAC number
310
US EPA chemical code
-
PubChem CID
23662782
CLP index number
No data found
Molecular mass
152.08
PIN (Preferred Identification Name)
sodium 6-oxo-1,6-dihydropyridazin-3-olate
IUPAC name
sodium 6-oxo-1,6-dihydropyridazin-3-olate
CAS name
1,2-dihydro-3,6-pyridazinedione sodium salt (1:1)
Other status information
Chemical subject to PIC regulations
Relevant Environmental Water Quality Standards
-
Herbicide Resistance Classification (HRAC)
Not known
Herbicide Resistance Classification (WSSA)
Not known
Insecticide Resistance Classification (IRAC)
Not applicable
Fungicide Resistance Classification (FRAC)
Not applicable
Examples of recorded resistance
-
Physical state
White crystalline solid
Related substances & organisms
Formulations
Property
Value
Example manufacturers & suppliers of products using this active now or historically
-
Example products using this active
-
Formulation and application details
Usually supplied in liquid formulations
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
- - -
Solubility - In organic solvents at 20 °C (mg l⁻¹)
- - -
Melting point (°C)
- - -
Boiling point (°C)
- - -
Degradation point (°C)
- - -
Flashpoint (°C)
- - -
Octanol-water partition coefficient at pH 7, 20 °C
P
- - -
Log P
- - -
Fat solubility of residues
Solubility
- - -
Data type
- - -
Density (g ml⁻¹)
- - -
Dissociation constant pKa) at 25 °C
- - -
-
Vapour pressure at 20 °C (mPa)
- - -
Henry's law constant at 25 °C (Pa m³ mol⁻¹)
- - -
Maximum UV-vis absorption L mol⁻¹ cm⁻¹
- - -
Surface tension (mN m⁻¹)
- - -
Degradation
Property
Value
Source; quality score; and other information
Interpretation
General biodegradability
-
Soil degradation (days) (aerobic)
DT₅₀ (typical)
- - -
DT₅₀ (lab at 20 °C)
- - -
DT₅₀ (field)
- - -
DT₉₀ (lab at 20 °C)
- - -
DT₉₀ (field)
- - -
DT₅₀ modelling endpoint
- - -
Note
-
Dissipation rate RL₅₀ on plant matrix
Value
- - -
Note
-
Dissipation rate RL₅₀ on and in plant matrix
Value
- - -
Note
-
Aqueous photolysis DT₅₀ (days) at pH 7
Value
- - -
Note
-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7
Value
- - -
Note
-
Water-sediment DT₅₀ (days)
- - -
Water phase only DT₅₀ (days)
- - -
Soil adsorption and mobility
Property
Value
Source; quality score; and other information
Interpretation
Linear
Kd
- - -
Koc
-
Notes and range
-
Freundlich
Kf
- - -
Kfoc
-
1/n
-
Notes and range
-
pH sensitivity
-
Fate indices
Property
Value
Source; quality score; and other information
Interpretation
GUS leaching potential index
- - -
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate
Value
Cannot be calculated - -
Note
-
Potential for particle bound transport index
- - -
Potential for loss via drain flow
- - -
Bio-concentration factor
BCF (l kg⁻¹)
- - -
CT₅₀ (days)
- -
Known soil metabolites
Metabolite
Major/Minor fraction
Estimated maximum occurrence fraction
Notes
maleic acid
Major fraction - -
Known groundwater metabolites

None

Other known metabolites

None

ECOTOXICOLOGY
Terrestrial ecotoxicology
Property
Value
Source; quality score; and other information
Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
> 10760
Q4 Q = Miscellaneous data from online sources
4 = Verified data
Rat		 Low
Mammals - Short term dietary NOEL
(mg kg⁻¹)
- - -
(ppm diet)
- -
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)
- - -
Birds - Acute LD₅₀ (mg kg⁻¹)
> 2000
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
Anas platyrhynchos		 Low
Birds - Short term dietary (LC₅₀/LD₅₀)
- - -
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)
- - -
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)
- - -
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)
- - -
Soil micro-organisms
- - -
Collembola
Acute LC₅₀ (mg kg⁻¹)
- - -
Chronic NOEC (mg kg⁻¹)
- - -
Non-target plants
- - -
- - -
Honeybees (Apis spp.)
Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
- - -
Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
- - -
Unknown mode acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
- - -
Chronic
- - -
Bumblebees (Bombus spp.)
Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
- - -
-
Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
- - -
-
Mason bees (Osmia spp.)
Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
- - -
Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
- - -
Other bee species (1)
Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)
- - -
Mode of exposure
-
Other bee species (2)
Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)
- - -
Mode of exposure
-
Beneficial insects (Ladybirds)
- - -
Beneficial insects (Lacewings)
- - -
Beneficial insects (Parasitic wasps)
- - -
Beneficial insects (Predatory mites)
- - -
Beneficial insects (Ground beetles)
- - -
Aquatic ecotoxicology
Property
Value
Source; quality score; and other information
Interpretation
Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
> 1000
A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
4 = Verified data
Oncorhynchus mykiss		 Low
Fish - Chronic 21 day NOEC (mg l⁻¹)
9.6
A4 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications )
4 = Verified data
Pimephales promelas 32 day		 Moderate
Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)
- - -
Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)
- - -
Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)
- - -
Sediment dwelling organisms - Acute 96 hour LC₅₀ (mg l⁻¹)
- - -
Sediment dwelling organisms - Chronic 28 day NOEC, static, water (mg l⁻¹)
- - -
Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg⁻¹)
- - -
Aquatic plants - Acute 7 day EC₅₀, biomass (mg l⁻¹)
- - -
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)
- - -
Algae - Chronic 96 hour NOEC, growth (mg l⁻¹)
- - -
Mesocosm study data
NOEAEC mg l⁻¹
- - -
NOEAEC mg l⁻¹
- - -
HUMAN HEALTH AND PROTECTION
General
Property
Value
Source; quality score; and other information
Interpretation
Threshold of Toxicological Concern (Cramer Class)
High (class III) - -
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
> 10760
Q4 Q = Miscellaneous data from online sources
4 = Verified data
Rat		 Low
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)
2000
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
Rat		 -
Mammals - Inhalation LC₅₀ (mg l⁻¹)
- - -
Other Mammal toxicity endpoints
- - -
ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)
- - -
ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)
- - -
AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)
- - -
AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)
- - -
Dermal penetration studies (%)
- - -
Dangerous Substances Directive 76/464
- - -
Exposure Routes
Public
No unacceptable risks to bystanders identified
Occupational
No unacceptable risks to operators or other workers identified
MRLs
European
EU MRL pesticide database 
Great Britain
GB MRL Register 
Notes
-
Drinking Water Standards
- - -
Drinking Water MAC (μg l⁻¹)
- - -
Mammalian dose elimination route and rate
- - -
Health issues
Specific human health issues
Carcinogen
Genotoxic
Endocrine disruptor
XNo, known not to cause a problem
A3 A = Chromosome aberration (EFSA database)
3 = Negative
;
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
;
E2 E = Unspecified genotoxicity type (miscellaneous data source)
2 = Mixed/ambiguous results
XNo, known not to cause a problem
Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant
XNo, known not to cause a problem
XNo, known not to cause a problem
✓Yes, known to cause a problem
Respiratory tract irritant Skin irritant Skin sensitiser
✓Yes, known to cause a problem
✓Yes, known to cause a problem
XNo, known not to cause a problem
Eye irritant Phototoxicant  
✓Yes, known to cause a problem
XNo, known not to cause a problem
  
General human health issues
Potential liver toxicant
Possible mutagen
Ingestion might cause tremors and muscle spasms
IARC group 3 carcinogen
Handling issues
Property
Value and interpretation
General
IMDG Transport Code is usually 9
Not explosive or oxidising
Not expected to autoignite; Not highly flammable
CLP classification 2013
Health: H315, H319, H341, H335
WHO Classification
U (Unlikely to present an acute hazard)
UN Number
Usually 3077
Waste disposal & packaging
Packaging Group III (minor danger)
TRANSLATIONS
Language
Name
English
maleic hydrazide sodium
French
-
German
-
Danish
-
Italian
-
Spanish
-
Greek
-
Polish
-
Swedish
-
Hungarian
-
Dutch
-
Norwegian
-
Record last updated: 23/01/2023
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