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Crotoxyphos (Ref: ENT 24717)
Last updated: 28/08/2024
(Also known as: crotoxyfos; cyodrin; decrotox; Kemdrin; ciodrin; SC 4294)

GENERAL INFORMATION
Description
An obsolete organophosphate insecticide used in veterinary medicine for the control of ectoparasites
Availability status
Considered obsolete but may be available in some countries
Introduction & key dates
1962, first reported
Examples of veterinary uses
Used to control external insect pests such as flies, mites and ticks
Examples of species treated
Cattle; Pigs; Goats; Horses; Sheep
Approval status
VMR 2013/2033 approval status (GB/UK)
Not approved
EU Regulatory approval status
Not approved
Chemical structure
Isomerism
Crotoxyphos is a chiral molecule. The technical material is an isomeric mixture.
Chemical formula
C₁₄H₁₉O₆P
Canonical SMILES
CC(C1=CC=CC=C1)OC(=O)C=C(C)OP(=O)(OC)OC
Isomeric SMILES
CC(C1=CC=CC=C1)OC(=O)/C=C(\C)/OP(=O)(OC)OC
International Chemical Identifier key (InChIKey)
XXXSILNSXNPGKG-ZHACJKMWSA-N
International Chemical Identifier (InChI)
InChI=1S/C14H19O6P/c1-11(20-21(16,17-3)18-4)10-14(15)19-12(2)13-8-6-5-7-9-13/h5-10,12H,1-4H3/b11-10+
2D structure diagram/image available?
Yes
General status
Veterinary substance type
Antiparasitic
Substance groups
Organophosphate substance
Minimum active substance purity
-
Known relevant impurities
-
Substance origin
Synthetic
Mode of action
A contact and stomach poison. Acetylcholinesterase (AchE) inhibitor.
Molecular targets
[Cholinesterase, Inhibitor]
CAS RN
7700-17-6
EC number
231-720-5
CIPAC number
329
US EPA chemical code
058801
PubChem CID
5371578
Therapeutic Class
-
ATCvet Code
None allocated
Controlled Drug?
No
Regulation 37/2010 MRL Classification
-
Molecular mass
314.27
PIN (Preferred Identification Name)
rac-(1R)-1-phenylethyl (2E)-3-[(dimethoxyphosphoryl)oxy]but-2-enoate
IUPAC name
(RS)-1-phenylethyl 3-(dimethoxyphosphinoyloxy)isocrotonate
CAS name
1-phenylethyl (2E)-3-[(dimethoxyphosphinyl)oxy]-2-butenoate
Other status information
-
Relevant Environmental Water Quality Standards
-
Physical state
Colourless to light straw-coloured liquid depending upon purity
Formulations
Property
Product
Manufacturer
Authorisation Route
Legal Class (GB/UK)
Example products (past and present) using this active
- - - -
Formulation and application details
-
ENVIRONMENTAL FATE
Property
Value
Source; quality score; and other information
Interpretation
Solubility - In water at 20 °C (mg l⁻¹)
1000
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID )
3 = Unverified data of known source
at 25 °C
High
Solubility - In organic solvents at 20 °C (mg l⁻¹)
- - -
Melting point (°C)
25
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
-
Boiling point (°C)
- - -
Degradation point (°C)
- - -
Flashpoint (°C)
- - -
Octanol-water partition coefficient at pH 7, 20 °C
P
2.00 X 1003 Calculated -
Log P
3.3
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID )
3 = Unverified data of known source
High
Fat solubility of residues
Solubility
- - -
Data type
- - -
Density (g ml⁻¹)
- - -
Dissociation constant pKa) at 25 °C
- - -
-
Vapour pressure at 20 °C (mPa)
1.9
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
Low volatility. If applied directly to plants or soil, drift is a concern & mitigation is advisable
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)
- - -
Refractive Index
- - -
Environmental release
-
Degradation
Property
Value
Source; quality score; and other information
Interpretation
Soil degradation (days) (aerobic)
DT₅₀ (typical)
1.5
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)
- - -
Note
Literature DT₅₀ range 2 to 71 hours (R4)
Manure DT₅₀ (days)
- - -
Aqueous photolysis DT₅₀ (days) at pH 7
Value
- - -
Note
-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7
Value
-
R4 R = Peer reviewed scientific publications
4 = Verified data
-
Note
pH sensitive: 540hrs at pH 2, 410hrs at pH 6 and 180hr at pH 9.0
Water-sediment DT₅₀ (days)
- - -
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.
Decay in stored produce DT₅₀
-
Soil adsorption and mobility
Property
Value
Source; quality score; and other information
Interpretation
Linear
Kd (mL g⁻¹)
-
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
Moderately mobile
Koc (mL g⁻¹)
170
Notes and range
Log10 Koc 2.23
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
0.31 Calculated Low leachability
Bio-concentration factor
BCF (l kg⁻¹)
- - -
CT₅₀ (days)
- -
Known metabolites

None

ECOTOXICOLOGY
Terrestrial ecotoxicology
Property
Value
Source; quality score; and other information
Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)
66
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID )
3 = Unverified data of known source
Rat
High
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)
520
F4 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 )
4 = Verified data
Coturnix japonica
Moderate
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)
> 2.31
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
Moderate
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
Temperate Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
0.06
F4 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 )
4 = Verified data
Oncorhynchus mykiss
High
Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)
- - -
Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)
- - -
Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)
- - -
Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)
- - -
Tropical Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (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
- - -
Marine bivalves
- - -
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)
66
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID )
3 = Unverified data of known source
Rat
High
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)
447
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID )
3 = Unverified data of known source
Rat
-
Mammals - Inhalation LC₅₀ (mg l⁻¹)
88
V3 V = ChemID Online Databases; Chemspider; PubChem. (ChemID )
3 = Unverified data of known source
Rat
-
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
List I - -
Exposure Routes
Public
-
Occupational
-
Mammalian dose elimination route and rate
Rapidly eliminated (~48 hrs) mainly via the urine (~80%)
Q3 Q = Miscellaneous data from online sources
3 = Unverified data of known source
-
Health issues
Specific human health issues
Carcinogen
Genotoxic
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
Yes, known to cause a problem
Yes, known to cause a problem
Respiratory tract irritant Skin irritant Skin sensitiser
No data found No data found No data found
Eye irritant Phototoxicant  
No data found No data found  
General human health issues
Toxic
May cause bradycardia or tachycardia
May cause respiratory problems
Handling issues
Property
Value and interpretation
General
No information available
CLP classification 2013
-
WHO Classification
Not classified: Obsolete (Not classified: Obsolete)
UN Number
-
Waste disposal & packaging
-
Shelf-life, storage, stability and reactivity
-
TRANSLATIONS
Language
Name
English
crotoxyphos
French
crotoxyphos
German
Crotoxyphos
Danish
-
Italian
-
Spanish
crotoxifos
Greek
-
Polish
-
Swedish
-
Hungarian
-
Dutch
-
Norwegian
-

Record last updated: 28/08/2024
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