| dithiopyr (Ref: RH 101664) |
 |
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SUMMARY
Dithiopyr is a pre-emergent herbicide without EU regulatory approval for use. It has a low aqueous solubility and, based on its chemical properties, is not expected to leach to groundwater. It is usually persistent in both soil and aquatic systems. It has a low toxicity to mammals and birds but is moderately toxic to most aquatic life, honey bees and earthworms. GENERAL INFORMATION 
for dithiopyr
Description: A pre-emergence and early post-emergence herbicide used for the control of grasses and broad-leaved weeds
Example pests controlled: Crabgrass; Annual bluegrass; Bermudagrass; Chickweed; Common knotweed; Purslane; Woodsorrel; Spotted spurge
Example applications: Residential and ornametal lawns; Turf areas including golf courses, sports fields
Efficacy & activity: -
Availability status: Current
Introduction & key dates: 1991, USA
EC Regulation 1107/2009 (repealing 91/414):
| Status | Not approved |
| Dossier rapporteur/co-rapporteur | Not applicable |
| Date inclusion expires | Not applicable |
| 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 | - |
| Chemical formula | C15H16F5NO2S2 |
| Canonical SMILES | CC(C)CC1=C(C(=NC(=C1C(=O)SC)C(F)(F)F)C(F)F)C(=O)SC |
| Isomeric SMILES | No data |
| International Chemical Identifier key (InChIKey) | YUBJPYNSGLJZPQ-UHFFFAOYSA-N |
| International Chemical Identifier (InChI) | InChI=1S/C15H16F5NO2S2/c1-6(2)5-7-8(13(22)24-3)10(12(16)17)21-11(15(18,19)20)9(7)14(23)25-4/h6,12H,5H2,1-4H3 |
| 2D structure diagram/image available? | Yes |
General status:
| Pesticide type | Herbicide | |
| Substance group | Pyridine compound | |
| Minimum active substance purity | - | |
| Known relevant impurities | - | |
| Substance origin | Synthetic | |
| Mode of action | Inhibits cell division - a mitotic inhibitor of normal cell division in susceptible plants. Thought to alter microtubule polymerization. | |
| CAS RN | 97886-45-8 | |
| EC number | - | |
| CIPAC number | None allocated | |
| US EPA chemical code | 128994 | |
| PubChem CID | 91757 | |
| Molecular mass (g mol-1) | 401.42 | |
| PIN (Preferred Identification Name) | S3,S5-dimethyl 2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl)pyridine-3,5-dicarbothioate | |
| IUPAC name | S,S'-dimethyl 2-difluoromethyl-4-isobutyl-6-trifluoromethylpyridine-3,5-dicarbothioate | |
| CAS name | S,S'-dimethyl 2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl)-3,5-pyridinedicarbothioate | |
| Other status information | - | |
| Relevant Environmental Water Quality Standards | - | |
| Herbicide Resistance Classification (HRAC) | K1 | |
| Herbicide Resistance Classification (WSSA) | 3 | |
| Insecticide Resistance Classification (IRAC) | Not applicable | |
| Fungicide Resistance Classification (FRAC) | Not applicable | |
| Examples of recorded resistance | - | |
| Physical state | Off-white coloured powder with sulphurous odour | |
| 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 dithiopyr
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Solubility - In water at 20oC (mg l-1) | 1.38 | F4 | Low | |
| Solubility - In organic solvents at 20oC (mg l-1) | 33000 | F4 - Hexane | - | |
| 250000 | F4 - Toluene | - | ||
| 500000 | F4 - Diethyl ether | - | ||
| 120000 | F4 - Ethanol | - | ||
| Melting point (oC) | 65 | F4 | - | |
| Boiling point (oC) | - | - | - | |
| Degradation point (oC) | - | - | - | |
| Flashpoint (oC) | - | - | - | |
| Octanol-water partition coefficient at pH 7, 20oC | P | 7.59 X 1005 | Calculated | - |
| Log P | 5.88 | K3 | High | |
| Bulk density (g ml-1)/Specific gravity | 1.413 | F4 | - | |
| Dissociation constant (pKa) at 25oC | N/a | F4 | - | |
| Note: No dissociation | ||||
| Vapour pressure at 20oC (mPa) | - | - | - | |
| Henry's law constant at 25oC (Pa m3 mol-1) | - | - | - | |
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 | 5.38 X 10-02 | Calculated | - |
| Note | - | |||
| Potential for particle bound transport index |
- | Calculated | Low | |
| Maximum UV-vis absorption L mol-1 cm-1 | - | - | - | |
| Surface tension (mN m-1) | - | - | - | |
Degradation:
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
General biodegradability | - |
| Soil degradation (days) (aerobic) | DT50 (typical) | 39 | L3 | Moderately persistent |
| DT50 (lab at 20oC) | - | - | - | |
| DT50 (field) | 39 | F3 | Moderately persistent | |
| DT90 (lab at 20oC) | - | - | - | |
| DT90 (field) | - | - | - | |
| DT50 modelling endpoint | - | - | - | |
| Note | General literature values DT50 range 17-61 days; Other sources: DT50 400 days (US3) | |||
| Dissipation rate RL50 on plant matrix | Value | 3.6 | R3 | - |
| Note | Turfgrass, n=1 | |||
| Dissipation rate RL50 on and in plant matrix | Value | 3.9 | R3 | - |
| Note | Perennial ryegrass, n=1 | |||
| Aqueous photolysis DT50 (days) at pH 7 | Value | 19.1 | F4 | Slow |
| Note | - | |||
| Aqueous hydrolysis DT50 (days) at 20oC and pH 7 | Value | Stable | F4 | - |
| Note | Not pH sensitive | |||
| Water-sediment DT50 (days) | - | - | - | |
| Water phase only DT50 (days) | - | - | - | |
Soil adsorption and mobility:
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Linear | Kd | - | US3 | Slightly mobile |
| Koc | 801 | |||
| Notes and range | - | |||
| Freundlich | Kf | - | - | - |
| Kfoc | - | |||
| 1/n | - | |||
| Notes and range | - | |||
| pH sensitivity | - | |||
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Bio-concentration factor | BCF (l kg-1) | - | - | - |
| CT50 (days) | - | - | ||
| Mammals - Acute oral LD50 (mg kg-1) | > 5000 | F4 Rat | Low | |
| Mammals - Short term dietary NOEL | (mg kg-1) | - | - | - |
| (ppm diet) | - | - | ||
| Birds - Acute LD50 (mg kg-1) | > 5620 | F5 Anas platyrhynchos | Low | |
| Birds - Short term dietary (LC50/LD50) | - | - | - | |
| Fish - Acute 96 hour LC50 (mg l-1) | 0.36 | F5 Oncorhynchus mykiss | Moderate | |
| Fish - Chronic 21 day NOEC (mg l-1) | 0.052 | F3 Oncorhynchus mykiss | Moderate | |
| Aquatic invertebrates - Acute 48 hour EC50 (mg l-1) | 14 | F5 Daphnia magna | Moderate | |
| Aquatic invertebrates - Chronic 21 day NOEC (mg l-1) | - | - | - | |
| Aquatic crustaceans - Acute 96 hour LC50 (mg l-1) | 0.47 | F3 Americamysis bahia | Moderate | |
| 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) | 0.02 | F5 Pseudokirchneriella subcapitata | Moderate | |
| Algae - Chronic 96 hour NOEC, growth (mg l-1) | - | - | - | |
| Honeybees (Apis spp.) | Contact acute LD50 (worst case from 24 , 48 and 72 hour values - μg bee-1) | > 53 | F5 | Moderate |
| 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) | - | - | - | |
| 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 pollinators (1) | Acute LD50 (worst case from 24 , 48 and 72 hour values - μg insect-1) | - | - | - |
| Mode of exposure | - | |||
| Other pollinators (2) | Acute LD50 (worst case from 24 , 48 and 72 hour values - μg insect-1) | - | - | - |
| Mode of exposure | - | |||
| Earthworms - Acute 14 day LC50 (mg kg-1) | > 1000 | E3 | 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 dithiopyr
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) | > 5000 | F4 Rat | Low | |
| Mammals - Dermal LD50 (mg kg-1 body weight) | > 5000 | F4 Rat | - | |
| Mammals - Inhalation LC50 (mg l-1) | > 5.98 | F4 Rat, 4 hr (nose only) | - | |
| 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) | a=0.25, b=0.75 | E3 mg/m3, a=TWA, b=STEL | - | |
| Dermal penetration studies (%) | - | - | - | |
| Dangerous Substances Directive 76/464 | List II | - | - | |
| Exposure Routes | Public | - | ||
| Occupational | PPE/PPC required to mitigate risks of exposure | |||
| European MRLs | Click here for the EU MRL pesticide database | |||
| Drinking Water Standards | - | - | - | |
| Drinking Water MAC (μg l-1) | - | - | - | |
Health issues:
| Carcinogen | Genotoxic | Endocrine disrupter | Reproduction / development effects | Cholinesterase inhibitor | Neurotoxicant | |||
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A0; B0; C0; D0; E3 | - |
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| Respiratory tract irritant | Skin irritant | Skin sensitiser | Eye irritant | Phototoxicant | ||||
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| General human health issues | Do not inhale Possible blood, kidney and liver toxicant |
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| Key: Genotoxicity A: Chromosome aberration (EFSA database) B: DNA damage/repair (EFSA database) C: Gene mutation (EFSA database) D: Genome mutation (EFSA database) E: Unspecified genotoxicity type (miscellaneous data source) 0: No data 1: Positive 2: Mixed/ambiguous results 3: Negative |
Key: Other : Yes, known to cause a problem  : No, known not to cause a problem  : Possibly, status not identified - : No data found |
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Handling issues:
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| General |
No information available | |||
| CLP classification 2013 | Environment: H400, H410 | |||
| EC Risk Classification |
Xi - Irritant: R36/38 N - Dangerous for the environment: R50/53 |
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| EC Safety Classification |
- | |||
| WHO Classification | U | - | Unlikely to present an acute hazard | |
| UN Number | - | |||
| Waste disposal & packaging |
- | |||
| Language | Name |
| English | dithiopyr |
| French | dithiopyr |
| German | Dithiopyr |
| Danish | dithiopyr |
| Italian | dithiopyr |
| Spanish | ditiopir |
| Greek | - |
| Slovenian | ditiopir |
| Polish | ditiopyr |
| Swedish | - |
| Hungarian | - |
| Dutch | - |
Record last updated: Friday 28 June 2019
Contact: aeru@herts.ac.uk