| imazapic (Ref: AC 263222) |
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SUMMARY
Imazapic is a selective pre- and post-emergent herbicide without EU regulatory approval for use. It has a high aqueous solubility, is volatile and, based on its chemical properties, is moderately mobile and may leach to groundwater. It is may be persistent in soil systems but usually degrades quickly in aquatic systems via photolysis. It has a low mammalian toxicity and has a high potential for bioaccumulation. It has a low level of toxicity to birds but is more toxic to aquatic life and honey bees. GENERAL INFORMATION 
for imazapic
Description: A selective herbicide used for both the pre- and post-emergent control of some grasses and broad-leaved weeds.
Example pests controlled: Annual and perennial grasses and some broad-leaved weeds
Example applications: Peanuts; Rangeland; Non-cropped areas
Efficacy & activity: -
Availability status: Current
Introduction & key dates: 1996
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 | Imazapic is a molecule with one chiral centre. The technical material is an isomeric mixture. |
| Chemical formula | C14H17N3O3 |
| Canonical SMILES | CC1=CN=C(C(=C1)C(=O)O)C2=NC(C(=O)N2)(C)C(C)C |
| Isomeric SMILES | No data |
| International Chemical Identifier key (InChIKey) | PVSGXWMWNRGTKE-UHFFFAOYSA-N |
| International Chemical Identifier (InChI) | InChI=1S/C14H17N3O3/c1-7(2)14(4)13(20)16-11(17-14)10-9(12(18)19)5-8(3)6-15-10/h5-7H,1-4H3,(H,18,19)(H,16,17,20) |
| Structure diagram/image available? | Yes |
General status:
| Pesticide type | Herbicide | |
| Substance group | Imidazolinone | |
| Minimum active substance purity | - | |
| Known relevant impurities | - | |
| Substance origin | Synthetic | |
| Mode of action | Selective, systemic, contact and residual activity, inhibiting the production of amino acids necessary for cell division and growth. Inhibits plant amino acid synthesis - acetohydroxyacid synthase AHAS. | |
| CAS RN | 104098-48-8 | |
| EC number | - | |
| CIPAC number | None allocated | |
| US EPA chemical code | 129041 | |
| PubChem CID | 91770 | |
| Molecular mass (g mol-1) | 275.30 | |
| PIN (Preferred Identification Name) | rac-5-methyl-2-[(4R)-4-methyl-5-oxo-4-(propan-2-yl)-4,5-dihydro-1H-imidazol-2-yl]pyridine-3-carboxylic acid | |
| IUPAC name | 2-[(RS)-4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl]-5-methylnicotinic acid | |
| CAS name | 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-methyl-3-pyridinecarboxylic acid | |
| Other status information | - | |
| Relevant Environmental Water Quality Standards | - | |
| Herbicide Resistance Classification (HRAC) | B | |
| Herbicide Resistance Classification (WSSA) | 2 | |
| Insecticide Resistance Classification (IRAC) | Not applicable | |
| Fungicide Resistance Classification (FRAC) | Not applicable | |
| Examples of recorded resistance | Amaranthus palmeri | |
| Physical state | Pale tan coloured 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 | Often supplied as watter dispersible granules. | |||
ENVIRONMENTAL FATE
for imazapic
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Solubility - In water at 20oC (mg l-1) | 2230 | V3 - @ 25 DegC | High | |
| Solubility - In organic solvents at 20oC (mg l-1) | 18.9 | L3 - Acetone | - | |
| Melting point (oC) | 205 | L3 | - | |
| Boiling point (oC) | - | - | - | |
| Degradation point (oC) | - | - | - | |
| Flashpoint (oC) | - | - | - | |
| Octanol-water partition coefficient at pH 7, 20oC | P | 2.95 X 1002 | Calculated | - |
| Log P | 2.47 | V3 | Low | |
| Bulk density (g ml-1)/Specific gravity | 1.31 | Q2 | - | |
| Dissociation constant (pKa) at 25oC | 2.0 | L3 | - | |
| Note: Strong acid; pKa(2) 3.6; pKa(3) 11.1 | ||||
| Vapour pressure at 20oC (mPa) | 0.01 | L3 | Low volatility | |
| Henry's law constant at 25oC (Pa m3 mol-1) | - | - | - | |
GUS leaching potential index  |
3.87 | Calculated | High leachability | |
| SCI-GROW groundwater index (μg l-1) for a 1 kg ha-1 or 1 l ha-1 application rate |
Value | 1.08 X 10+00 | Calculated | - |
| Note | - | |||
| Potential for particle bound transport index |
- | Calculated | Medium | |
| 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) | 120 | Q3 | Persistent |
| DT50 (lab at 20oC) | - | - | - | |
| DT50 (field) | 232 | F3 | Persistent | |
| DT90 (lab at 20oC) | - | - | - | |
| DT90 (field) | - | - | - | |
| DT50 modelling endpoint | - | - | - | |
| Note | Literature DT50 values range 31-410 days. Main degradation route is microbial. | |||
| 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 | 0.3 | L3 | Fast |
| 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 | - | US3 | Moderately mobile |
| Koc | 137 | |||
| Notes and range | - | |||
| Freundlich | Kf | - | - | - |
| Kfoc | - | |||
| 1/n | - | |||
| Notes and range | - | |||
| pH sensitivity | - | |||
Key metabolites:
| Metabolite | Formation medium | Estimated maximum occurrence fraction | 1107/2009 relevancy |
|
| 2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl)-3,5,pyridinecarboxylic acid (Ref: CL-312622) |
Soil | 0.1 | - | |
| Property |
Value | Source/Quality Score/Other Information |
Interpretation |
|
| Bio-concentration factor | BCF (l kg-1) | Low risk | Q3 Based on LogP < 3 | Low potential |
| CT50 (days) | - | - | ||
| Mammals - Acute oral LD50 (mg kg-1) | > 5000 | R4 Rat | Low | |
| Mammals - Short term dietary NOEL | (mg kg-1) | - | - | - |
| (ppm diet) | - | - | ||
| Birds - Acute LD50 (mg kg-1) | > 2150 | L3 Anas platyrhynchos | Low | |
| Birds - Short term dietary (LC50/LD50) | - | - | - | |
| Fish - Acute 96 hour LC50 (mg l-1) | > 100 | R4 Oncorhynchus mykiss | Low | |
| Fish - Chronic 21 day NOEC (mg l-1) | - | - | - | |
| Aquatic invertebrates - Acute 48 hour EC50 (mg l-1) | > 100 | R4 Daphnia magna | Low | |
| Aquatic invertebrates - Chronic 21 day NOEC (mg l-1) | - | - | - | |
| Aquatic crustaceans - Acute 96 hour LC50 (mg l-1) | > 97.7 | F4 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) | 0.051 | L3 Pseudokirchneriella subcapitata | Moderate | |
| Algae - Chronic 96 hour NOEC, growth (mg l-1) | - | - | - | |
| Honeybees | Contact acute 48 hour LD50 (μg bee-1) | > 100000 | R4 | Low |
| 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) | - | - | - | |
| 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 imazapic
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 | R4 Rat | Low | |
| Mammals - Dermal LD50 (mg kg-1 body weight) | > 2000 | R4 Rabbit | - | |
| Mammals - Inhalation LC50 (mg l-1) | > 4.83 | L3 Rat, 4 hr | - | |
| Other Mammal toxicity endpoints | - | - | ||
| ADI - Acceptable Daily Intake (mg kg-1bw day-1) | 0.5 | L3 | - | |
| 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 | - | |||
| 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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| Respiratory tract irritant | Skin irritant | Skin sensitiser | Eye irritant | Phototoxicant | ||||
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| General human health issues | No further information available | |||||||
: 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 |
No information available | |||
| CLP classification 2013 | - | |||
| EC Risk Classification |
Xi - Irritant: R36 | |||
| EC Safety Classification |
S22, S24/25, S36/37/39 | |||
| WHO Classification | NL | - | Not listed | |
| US EPA Classification (formulation) | III | - | Caution - Slightly toxic | |
| UN Number | - | |||
| Waste disposal & packaging |
- | |||
| Language | Name |
| English | imazapic |
| French | - |
| German | - |
| Danish | - |
| Italian | - |
| Spanish | imazapic |
| Greek | - |
| Slovenian | - |
| Polish | imazapik |
| Swedish | - |
| Hungarian | - |
| Dutch | - |
Record last updated: Thursday 31 May 2018
Contact: aeru@herts.ac.uk