Desmetryn is a selective herbicide. It has a high aqueous solubility and is volatile. Based on its chemical properties it is not expected to leach to groundwater. It is not usually persistent in soils but may persist in water under some conditions. Desmetryn is moderately toxic to mammals. It is moderately toxic to birds, most aquatic organisms and earthworms. It is relatively non-toxic to honeybees.
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
Environmental fate Moderate alert: Drainflow: Moderately mobile
Example manufacturers & suppliers of products using this active now or historically
Syngenta
Novartis
Ciba-Geigy
Example products using this active
Semeron
Formulation and application details
Usually supplied as a wettable powder
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
580
K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data
High
Solubility - In organic solvents at 20 °C (mg l⁻¹)
300000
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Methanol
-
230000
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Acetone
-
200000
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Toluene
-
2600
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
n-Hexane
-
Melting point (°C)
84
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
-
Boiling point (°C)
339
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
-
Degradation point (°C)
-
-
-
Flashpoint (°C)
-
-
-
Octanol-water partition coefficient at pH 7, 20 °C
P
2.40 X 1002
Calculated
-
Log P
2.38
K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data
Low
Fat solubility of residues
Solubility
-
-
-
Data type
-
-
-
Density (g ml⁻¹)
1.18
Q2 Q = Miscellaneous data from online sources 2 = Unverified data of unknown source
-
Dissociation constant pKa) at 25 °C
4
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source
-
Weak base
Vapour pressure at 20 °C (mPa)
1.30 X 10-01
K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data
Low volatility. If applied directly to plants, drift is a concern & mitigation is advisable
Henry's law constant at 25 °C (Pa m³ mol⁻¹)
4.89 X 10-05
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source
Non-volatile
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
-
Soil degradation (days) (aerobic)
DT₅₀ (typical)
9
K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data
Non-persistent
DT₅₀ (lab at 20 °C)
9
K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data
Non-persistent
DT₅₀ (field)
-
-
-
DT₉₀ (lab at 20 °C)
-
-
-
DT₉₀ (field)
-
-
-
DT₅₀ modelling endpoint
-
-
-
Note
Other literature quotes DT₅₀ soil 50 days (L3)
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
Stable
W4 W = French database provided by ARVALIS-Institut du Végétal. Dataset no longer available. 4 = Verified data
Stable
Note
-
Water-sediment DT₅₀ (days)
34
K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data
Moderately fast
Water 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.
Soil adsorption and mobility
Property
Value
Source; quality score; and other information
Interpretation
Linear
Kd
-
B3 B = UK CRD and ACP Evaluation Documents / and other DEFRA (UK) documents; Also Chemicals Regulation Division, Health and Safety Executive (HSE), UK (click here ) 3 = Unverified data of known source
Moderately mobile
Koc
150
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
1.74
Calculated
Low leachability
SCI-GROW groundwater index (μg l⁻¹) for a 1 kg ha⁻¹ or 1 l ha⁻¹ application rate
Value
2.37 X 10-02
Calculated
-
Note
-
Potential for particle bound transport index
Low
Calculated
-
Potential for loss via drain flow
Moderately mobile
Calculated
-
Photochemical oxidative DT₅₀ (hrs) as indicator of long-range air transport risk
-
-
-
Bio-concentration factor
BCF (l kg⁻¹)
21
Q2 Q = Miscellaneous data from online sources 2 = Unverified data of unknown source
Estimated
Low potential
CT₅₀ (days)
Not available
-
Known metabolites
None
ECOTOXICOLOGY
Terrestrial ecotoxicology
Property
Value
Source; quality score; and other information
Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
1390
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source
Rat
Moderate
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)
> 10000
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Coturnix japonica
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)
160
K4 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 4 = Verified data
Eisenia foetida
Moderate
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)
> 101
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Low
Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)
> 197
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Low
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)
Harmless
AA2 AA = IOBC Database on classification of side effects to beneficial organisms, 2005 2 = Unverified data of unknown source
Chrysoperla carnea
-
Beneficial insects (Parasitic wasps)
-
-
-
Beneficial insects (Predatory mites)
-
-
-
Beneficial insects (Ground beetles)
-
-
-
Aquatic ecotoxicology
Property
Value
Source; quality score; and other information
Interpretation
Temperate Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
2.2
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
Oncorhynchus mykiss
Moderate
Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)
-
-
-
Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
K3 K = Research datasets (e.g. Pandora, Demetra; these datasets no longer available). Norman Ecotoxicology database. (click here ) 3 = Unverified data of known source
Aquatic plants - Acute 7 day EC₅₀, biomass (mg l⁻¹)
-
-
-
Algae - Acute 72 hour EC₅₀, growth (mg l⁻¹)
0.025
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
Ankistrodesmus falcatus
Moderate
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)
1390
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID ) 3 = Unverified data of known source
Rat
Moderate
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)
2000
L3 L = Pesticide manuals and hard copy reference books / other sources 3 = Unverified data of known source
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
Environmental fate
