| difethialone (Ref: OMS 3053) |
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SUMMARY
Difethialone is a rodenticide not approved for use in Europe but is still used elsewhere. It is relatively volatile, has low potential to leach to groundwater but is highly persistent in soils. It is highly toxic to humans and considered to produce adverse effects on the reproduction system. it is also highly toxic to birds and aquatic life. GENERAL INFORMATION 
for difethialone
Description: A rodenticide for use against warfarin-resistant and warfarin-susceptible strains of Rattus norvegicus and Mus musculus
Example pests controlled: Rats; Mice; Other small rodents
Example applications: -
Efficacy & activity: -
Availability status: Current
Introduction & key dates: 1989, France
EC Regulation 1107/2009 (repealing 91/414):
| Status | Not approved |
| Dossier rapporteur/co-rapporteur | Norway |
| Date inclusion expires | Expired |
| EU Candidate for substitution (CfS) | - |
| Listed in EU database | Yes |
Approved for use (
) or known to be used (
) in the following European countries: 
AT |
BE |
BG |
CY |
CZ |
DE |
DK |
EE |
EL |
ES |
FI |
FR |
HR |
HU |
IE |
IT |
LT |
LU |
LV |
MT |
NL |
PL |
PT |
RO |
SE |
SI |
SK |
UK |
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Also used in: Australia, USA
Chemical structure:
| Isomerism | A molecule with 2 chiral centres |
| Chemical formula | C31H23BrO2S |
| Canonical SMILES | C1C(CC2=CC=CC=C2C1C3=C(SC4=CC=CC=C4C3=O)O)C5=CC=C(C=C5)C6=CC=C(C=C6)Br |
| Isomeric SMILES | No data |
| International Chemical Identifier key (InChIKey) | JHELOZJAKXYVBE-UHFFFAOYSA-N |
| International Chemical Identifier (InChI) | InChI=1S/C31H23BrO2S/c32-24-15-13-20(14-16-24)19-9-11-21(12-10-19)23-17-22-5-1-2-6-25(22)27(18-23)29-30(33)26-7-3-4-8-28(26)35-31(29)34/h1-16,23,27,33H,17-18H2 |
| 2D structure diagram/image available? | Yes |
General status:
| Pesticide type | Rodenticide | |||
| Substance group | Coumarin anticoagulant | |||
| Minimum active substance purity | 976 g/kg | |||
| Known relevant impurities | EU dossier - None declared | |||
| Substance origin | Synthetic | |||
| Mode of action | Anticoagulant, locks onto the rodent's liver enzyme | |||
| CAS RN | 104653-34-1 | |||
| EC number | - | |||
| CIPAC number | 549 | |||
| US EPA chemical code | 128967 | |||
| PubChem CID | 91771 | |||
| Molecular mass (g mol-1) | 539.48 | |||
| PIN (Preferred Identification Name) | 3-[(1E,3E)-3-(4'-bromo[1,1'-biphenyl]-4-yl)-1,2,3,4-tetrahydronaphthalen-1-yl]-4-hydroxy-2H-1-benzothiopyran-2-one where the ratios of the racemates (1RS,3RS) to (1RS,3SR) lie within the ranges 0–15 to 85–100 respectively | |||
| IUPAC name | 3-[3-(4'-bromo[1,1'-biphenyl]-4-yl)-1,2,3,4-tetrahydro-1-naphthalenyl]-4-hydroxy-2H-1-benzothiopyran-2-one | |||
| CAS name | - | |||
| Other status information | - | |||
| Relevant Environmental Water Quality Standards | - | |||
| Herbicide Resistance Classification (HRAC) | Not applicable | |||
| Herbicide Resistance Classification (WSSA) | Not applicable | |||
| Insecticide Resistance Classification (IRAC) | Not applicable | |||
| Fungicide Resistance Classification (FRAC) | Not applicable | |||
| Examples of recorded resistance | - | |||
| Physical state | White-yellow powder | |||
| Related substances & organisms | - | |||
Formulations:
| Property |
Value | |||
| Example manufacturers & suppliers of products using this active now or historically |
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| Example products using this active |
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| UK LERAP status | No UK approval for use as a pesticide under EC Regulation 1107/2009 | |||
| Formulation and application details | - | |||
ENVIRONMENTAL FATE
for difethialone
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Solubility - In water at 20oC (mg l-1) | 0.392 | A5 | Low | |
| Solubility - In organic solvents at 20oC (mg l-1) | 100000 | C4 - Acetone | - | |
| 14000 | A5 - Dichloromethane | - | ||
| 470 | L3 - Methanol | - | ||
| 200 | L3 - Hexane | - | ||
| Melting point (oC) | 235 | A5 | - | |
| Boiling point (oC) | - | - | - | |
| Degradation point (oC) | - | - | - | |
| Flashpoint (oC) | - | - | - | |
| Octanol-water partition coefficient at pH 7, 20oC | P | 1.95 X 1006 | Calculated | - |
| Log P | 6.29 | A5 | High | |
| Bulk density (g ml-1)/Specific gravity | 1.36 | L3 | - | |
| Dissociation constant (pKa) at 25oC | - | - | - | |
| Note: | ||||
| Vapour pressure at 20oC (mPa) | 0.0133 | A5 | Low volatility | |
| Henry's law constant at 25oC (Pa m3 mol-1) | 1.02 X 10-01 | L3 | Moderately volatile | |
GUS leaching potential index  |
-10.46 | Calculated | Low leachability | |
| SCI-GROW groundwater index (μg l-1) for a 1 kg ha-1 or 1 l ha-1 application rate |
Value | 5.35 X 10-03 | Calculated | - |
| Note | Estimated concentrations of chemicals with Koc values greater than 9995 ml g-1 are beyond the scope of the regression data used in SCI-GROW development. If there are concerns for such chemicals, a higher tier groundwater exposure assessment should be considered, regardless of the concentration returned by SCI-GROW | |||
| Potential for particle bound transport index |
- | Calculated | High | |
| Maximum UV-vis absorption L mol-1 cm-1 | Maxima at 234nm, 260nm and 330nm | A2 | - | |
| Surface tension (mN m-1) | - | - | - | |
Degradation:
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
General biodegradability | - |
| Soil degradation (days) (aerobic) | DT50 (typical) | 635 | A3 | Very persistent |
| DT50 (lab at 20oC) | 635 | A3 | Very persistent | |
| DT50 (field) | - | - | - | |
| DT90 (lab at 20oC) | - | - | - | |
| DT90 (field) | - | - | - | |
| DT50 modelling endpoint | - | - | - | |
| Note | EU dossier lab studies DT50 range 417-976 days, @12 degC | |||
| 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 20oC and pH 7 | Value | - | - | - |
| Note | - | |||
| Water-sediment DT50 (days) | - | - | - | |
| Water phase only DT50 (days) | - | - | - | |
Soil adsorption and mobility:
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Linear | Kd | - | L3 | Non-mobile |
| Koc | 54000000 | |||
| Notes and range | - | |||
| Freundlich | Kf | - | - | - |
| Kfoc | - | |||
| 1/n | - | |||
| Notes and range | - | |||
| pH sensitivity | - | |||
ECOTOXICOLOGY
for difethialone
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Bio-concentration factor | BCF (l kg-1) | 39974 | A5 | High potential |
| CT50 (days) | Not available | - | ||
| Mammals - Acute oral LD50 (mg kg-1) | 0.56 | F4 Rat | High | |
| Mammals - Short term dietary NOEL | (mg kg-1) | - | - | - |
| (ppm diet) | - | - | ||
| Birds - Acute LD50 (mg kg-1) | 0.264 | A5 Colinus virginianus | High | |
| Birds - Short term dietary (LC50/LD50) | 0.56 mg kg feed-1 | A5 Colinus virginianus | - | |
| Fish - Acute 96 hour LC50 (mg l-1) | 0.051 | A5 Oncorhynchus mykiss | High | |
| Fish - Chronic 21 day NOEC (mg l-1) | - | - | - | |
| Aquatic invertebrates - Acute 48 hour EC50 (mg l-1) | 0.0044 | A5 Daphnia magna | High | |
| 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) | - | - | - | |
| Non-target plants | - | - | - | |
| - | - | - | ||
| Algae - Acute 72 hour EC50, growth (mg l-1) | > 0.18 | A5 Pseudokirchneriella subcapitata | Moderate | |
| Algae - Chronic 96 hour NOEC, growth (mg l-1) | 0.032 | A5 Selenastrum capricornutum, Growth | Moderate | |
| Honeybees | Contact acute 48 hour LD50 (μg bee-1) | - | - | - |
| Oral acute 48 hour LD50 (μg bee-1) | - | - | - | |
| Unknown mode acute 48 hour LD50 (μg bee-1) | - | - | - | |
| Earthworms - Acute 14 day LC50 (mg kg-1) | > 1000 | A4 | Low | |
| Earthworms - Chronic 14 day NOEC, reproduction (mg kg-1) | - | - | - | |
| Other soil macro-organisms - e.g. Collembola | LR50 / EC50 / NOEC / % Effect | - | - | - |
| Other arthropod (1) | LR50 g ha-1 | - | - | - |
| % Effect | - | - | - | |
| Other arthropod (2) | LR50 g ha-1 | - | - | - |
| % Effect | - | - | - | |
| Soil micro-organisms | - | - | - | |
| Mesocosm study data | NOEAEC mg l-1 | - | - | - |
| NOEAEC mg l-1 | - | - | - | |
HUMAN HEALTH AND PROTECTION
for difethialone
General:
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Threshold of Toxicological Concern (Cramer Class) |
High (class III) | - | - | |
| Mammals - Acute oral LD50 (mg kg-1) | 0.56 | F4 Rat | High | |
| Mammals - Dermal LD50 (mg kg-1 body weight) | 5.3 | L3 Rat | - | |
| Mammals - Inhalation LC50 (mg l-1) | 0.005 | L3 Rat | - | |
| Other Mammal toxicity endpoints | - | - | ||
| ADI - Acceptable Daily Intake (mg kg-1bw day-1) | - | - | - | |
| ARfD - Acute Reference Dose (mg kg-1bw day-1) | - | - | - | |
| AAOEL - Acute Acceptable Operator Exposure Level (mg kg-1 bw day-1) | - | - | - | |
| AOEL - Acceptable Operator Exposure Level - Systemic (mg kg-1bw day-1) | - | - | - | |
| Dermal penetration studies (%) | - | - | - | |
| Dangerous Substances Directive 76/464 | - | - | - | |
| Exposure Limits | - | - | - | |
| Exposure Routes | Public | - | ||
| Occupational | May be absorbed through the skin | |||
| European MRLs | Click here for the EU MRL pesticide database | |||
| Drinking Water Standards | - | - | - | |
| Drinking Water MAC (μg l-1) | - | - | - | |
Health issues:
| Carcinogen | Mutagen | Endocrine disrupter | Reproduction / development effects | Cholinesterase inhibitor | Neurotoxicant | |||
- |
- |
- |
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- |
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| Respiratory tract irritant | Skin irritant | Skin sensitiser | Eye irritant | Phototoxicant | ||||
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| General human health issues | Highly toxic May cause severe haemorrhage leading to death |
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: Yes, known to cause a problem
: No, known not to cause a problem
: Possibly, status not identified
- : No data found
Handling issues:
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| General |
Not explosive or oxidising | |||
| CLP classification 2013 | None allocated at this time | |||
| EC Risk Classification |
Reproduction risk category 2: R61 T+ - Highly toxic: R26/27/28 T - Toxic: R48/23/24/25 N - Dangerous for the environment: R50, R53 |
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| EC Safety Classification |
S45, S53, S60, S61 | |||
| WHO Classification | Ia | - | Extremely hazardous | |
| US EPA Classification (formulation) | I | - | Danger - Highly toxic | |
| UN Number | 2588 | |||
| Waste disposal & packaging |
- | |||
| Language | Name |
| English | difethialone |
| French | difethialone |
| German | Difethialone |
| Danish | difethialon |
| Italian | difetialone |
| Spanish | difetialone |
| Greek | - |
| Slovenian | difetialon |
| Polish | difetialon |
| Swedish | - |
| Hungarian | - |
| Dutch | - |
Record last updated: Wednesday 23 May 2018
Contact: aeru@herts.ac.uk