The following Pesticide Hazard Tricolour (PHT) 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. The alerts for Highly Hazardous Pesticides (HHPs) are based on applying the FAO/WHO (Type 1) and the PAN (Type II) criteria to PPDB data. Further details on the HHP indicators are given in the tables below. Neither the PHT nor the HHP hazard alerts take account of usage patterns or exposure, thus they do not represent risk.
PHT: Environmental fate
PHT: Ecotoxicity
PHT: Human health
Highly Hazardous Pesticide
Environmental fate High alert: Drainflow: Very mobile
As an antimicrobial, MIT has several modes of action: (a) disruption of thiol proteins (Cellular Suffocation), (b) inhibition of microbial growth and metabolism, (c) destruction of microbe DNA structure, and (d) suppression of biofilms.
R01 Rule 1: Pesticide active ingredients that meet the criteria of classes Ia or Ib of the WHO Recommended Classification of Pesticides by Hazard; or those with a CLP classification of H330; or where Mammals acute oral LD₅₀ <= 50 mg kg⁻¹
]
Other status information
Some applications may be approved under national biocide regulations
Herbicide Resistance Class (HRAC MoA class)
Not applicable
Herbicide Resistance Class (WSSA MoA class)
Not applicable
Insecticide Resistance Class (IRAC MoA class)
Not applicable
Fungicide Resistance Class (FRAC MOA class)
Not applicable
Examples of recorded resistance
-
Physical state
White solid when pure but supplied as a clear liquid with alcohol type odour
Pure MIT is supplied as a solid but commercial MIT is normally supplied as a liquid formulation at typically 10% concentration.
Commercial production
Methylisothiazolinone (MIT) is produced commercially by chemical synthesis of the isothiazolinone ring, typically through formation of a suitable sulphur–nitrogen-containing intermediate followed by cyclisation and introduction of the methyl substituent. Industrial processes generally use controlled reactions involving sulphur, nitrogen and carbon-containing feedstocks, followed by purification, concentration and formulation as an aqueous solution. Commercial MIT is commonly supplied at relatively low concentrations because it is primarily used as a preservative/biocide in water-based products, including paints, coatings, adhesives, cleaning products and personal-care formulations.
Impact on climate of production and use
-
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C at pH 7 (mg l⁻¹)
959000
F3 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment ) 3 = Unverified data of known source
High
Solubility - In organic solvents at 20 °C (mg l⁻¹)
800000
Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source
Methanol
-
160000
Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source
Xylenol
-
Melting point (°C)
40
Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source
-
Boiling point (°C)
182
E3 E = Manufacturers safety data sheets 3 = Unverified data of known source
-
Degradation point (°C)
-
-
-
Flashpoint (°C)
64.3
Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source
-
Octanol-water partition coefficient at pH 7, 20 °C
E3 E = Manufacturers safety data sheets 3 = Unverified data of known source
-
Data type
Industry data
E3 E = Manufacturers safety data sheets 3 = Unverified data of known source
-
Density (g ml⁻¹)
1.35
Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source
-
Dissociation constant pKa) at 25 °C
-
-
-
-
Vapour pressure at 20 °C (mPa)
-
-
-
Henry's law constant at 25 °C (Pa m³ mol⁻¹)
-
-
-
Volatilisation as max % of applied dose lost
From plant surface
-
-
-
From soil surface
-
-
-
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
Generally concidered to be biodegradable at typical environmental concentrations. However, a high concentrations MIT can inhibit the microbes that cause its biodegradation significanty slowing the process.
Soil degradation (days)
DT₅₀ (typical)
0.3
R4 R = Peer reviewed scientific publications 4 = Verified data
Non-persistent
DT₅₀ (lab at 20 °C)
-
-
-
DT₅₀ (field)
-
-
-
DT₉₀ (lab at 20 °C)
-
-
-
DT₉₀ (field)
-
-
-
DT₅₀ modelling endpoint
-
-
-
Note
-
Soil mineralisation
Aerobic (at 20 °C)
-
-
-
Anaerobic (at 20 °C)
-
-
Dissipation rate RL₅₀ (days) on plant matrix
Value
-
-
-
Note
-
Dissipation rate RL₅₀ (days) 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)
-
-
-
Sediment phase only DT₅₀ (days)
-
-
-
Air degradation
As this parameter is not normally measured directly, a surrogate measure is used: ‘Photochemical oxidative DT₅₀’. Where data is available, this can be found in the Fate Indices section below.
Decay in stored produce DT₅₀
-
Soil adsorption and mobility
Property
Value
Source; quality score; and other information
Interpretation
Linear
Kd (mL g⁻¹)
-
E3 E = Manufacturers safety data sheets 3 = Unverified data of known source
Very mobile
Koc (mL g⁻¹)
12
Notes and range
estimate
Freundlich
Kf (mL g⁻¹)
-
-
-
Kfoc (mL g⁻¹)
-
1/n
-
Notes and range
-
pH sensitivity
-
Fate indices
Property
Value
Source; quality score; and other information
Interpretation
GUS leaching potential index
-1.53
Calculated
Low leachability
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate
Value
5.41 X 10-04
Calculated
-
Note
-
Potential for particle bound transport index
Low
Calculated
-
Potential for loss via drain flow
Very mobile
Calculated
-
Photochemical oxidative DT₅₀ (hrs) as indicator of long-range air transport risk
-
-
-
Bio-concentration factor
BCF (l kg⁻¹)
3.16
E3 E = Manufacturers safety data sheets 3 = Unverified data of known source
F3 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment ) 3 = Unverified data of known source
F3 F = U.S. EPA ECOTOX database / U.S. EPA pesticide fate database / Miscellaneous WHO documents / FAO data, IPCS INCHEM data (US EPA Databases Related to Pesticide Risk Assessment ) 3 = Unverified data of known source
Unknown species
Moderate
Mesocosm study data
NOEAEC mg l⁻¹
-
-
-
NOEAEC mg l⁻¹
-
-
-
Marine bivalves – embryo-laval development 48 hr EC₅₀ (mg l⁻¹)
F4 Crassostrea virginica 0.028
-
-
Regulatory Threshold Levels (RTLs)
Note: These RTLs have been calculated using the regulatory approach used in the European Union and based on ecotoxocity values in the PPDB.
Species group
RTL
Notes
Mammals
18.3
Worst case of acute and chronic mammals
Birds
27.8
Worst case of acute and chronic birds
Soil organisms
No data
No data for acute and chronic earthworms
Terrestrial plants
No data
No data for non-target plants vegetative vigour and seedling emergence
Pollinators
0.078
Worst case of contact and oral honeybees
Arthropods
No data
No data for parasitic wasps and predatory mites
Fish
0.003
Worst case of temperate acute and chronic fish
Aquatic invertebrates
0.0044
Worst case of temperate acute and chronic aquatic invertebrates
Aquatic plants
0.0157
Worst case of free-floating plants, rooted plants, acute and chronic algae
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
;
E3 E = Unspecified genotoxicity type (miscellaneous data source) 3 = Negative
No data found
Reproduction / development effects
Acetyl cholinesterase inhibitor
Neurotoxicant
No data found
No data found
?Possibly, status not identified
Respiratory tract irritant
Skin irritant
Skin sensitiser
✓Yes, known to cause a problem
✓Yes, known to cause a problem
✓Yes, known to cause a problem
Eye irritant
Phototoxicant
✓Yes, known to cause a problem
No data found
General human health issues
Strong allergen Cytotoxic May cause dermatitis Highly toxic by some exposure routes, potentially fatal if inhaled
Handling issues
Property
Value and interpretation
General
Incompatible with oxidising agents, amines, mercaptans and reducing agents Highly corrosive When heated to decomposition it emits toxic fumes IMDG Transport hazard class 9
Tzilivakis, J., Lewis, K.A., Green, A. and Warner, D.J. (2026) A decade of growth and impact of the Pesticide Properties Database (PPDB). Human and Ecological Risk Assessment: An International Journal, 32(6), 1104-1129. DOI: 10.1080/10807039.2026.2702066
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
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Environmental fate
Warning:
Ecotoxicity
