| Potassium phosphonates |

Last updated: 19/02/2026
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(Not known by any other names) |
The following Pesticide Hazard Tricolour (PHT) 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. The alerts for Highly Hazardous Pesticides (HHPs) are based on applying the FAO/WHO (Type 1) and the PAN (Type II) criteria to PPDB data. Further details on the HHP indicators are given in the tables below. Neither the PHT nor the HHP hazard alerts take account of usage patterns or exposure, thus they do not represent risk.
| PHT: Environmental fate |
PHT: Ecotoxicity |
PHT: Human health |
Highly Hazardous Pesticide |
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A mixture of two (mono- and di-) inorganic potassium salts that has fungicidal properties and is used to control Pythium and Phytophthora on a variety of fruit and ornamental crops |
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Root rot, damping-off, and stem rot caused by Pythium and Phytophthora species |
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Fruit including avocados, apples, grapes; Ornamentals; Trees; Salad leaves and lettuce; Garlic and shallots; Sprouts and shoots |
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- |
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- |
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- |
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Approved |
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31/01/31 |
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Crop over 5m - See Authorisation for Crop LERAP Details |
| EC Regulation 1107/2009 (repealing 91/414) |
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Approved |
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France |
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31/01/2026 |
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No |
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Yes |
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ATAustria |
BEBelgium |
BGBulgaria |
CYCyprus |
CZCzech Republic |
DEGermany |
DKDenmark |
EEEstonia |
ELGreece |
| ✓ |
✓ |
✓ |
✓ |
✓ |
✓ |
✓ |
✓ |
✓ |
ESSpain |
FIFinland |
FRFrance |
HRCroatia |
HUHungary |
IEIreland |
ITItaly |
LTLithuania |
LULuxembourg |
| ✓ |
✓ |
✓ |
✓ |
✓ |
✓ |
  |
✓ |
✓ |
LVLatvia |
MTMalta |
NLNetherlands |
PLPoland |
PTPortugal |
RORomania |
SESweden |
SISlovenia |
SKSlovakia |
| ✓ |
  |
✓ |
✓ |
✓ |
✓ |
✓ |
✓ |
✓ |
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ISIceland |
NONorway |
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|   |
  |
  |
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  |
  |
  |
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  |
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None |
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KH₂PO₃ & K₂HPO₃ |
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- |
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- |
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- |
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- |
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Yes |
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Fungicide |
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Inorganic compound; Micro-organism derived |
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- |
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- |
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Semi-synthetic |
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Mixed mode of application including direct toxicity to plant pathogens reducing populations and promotion of plants natural defences |
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Many phosphonates occur naturally in protozoa, mollusks, coelenterates, and oomycete fungi |
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Crop protection |
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Pythium spp.; Phytophthora spp. including root rot |
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Fruit including avocados, apples, grapes; Ornamentals; Trees; Salad leaves and lettuce; Garlic and shallots; Sprouts and shoots |
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- |
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13977-65-6 |
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- |
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- |
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076416 |
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- |
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756 |
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- |
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Reaction mixture of Potassium hydrogen phosphonate and dipotassium phosphonate |
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Reaction mixture of Potassium hydrogen phosphonate and dipotassium phosphonate |
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Reaction mixture of Potassium hydrogen phosphonate and dipotassium phosphonate |
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| UK Poisons List Order 1972 |
Rotterdam Convention |
Montreal Protocol |
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| Stockholm Convention |
OSPAR |
EU Water Framework Directive |
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- |
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- |
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- |
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Yes [ R11 Rule 11: Pesticide active ingredients that are environmentally persistent (where sediment phase only DT₅₀ => 90 days or water phase only DT₅₀ => 90 days or DT₅₀ (field) => 60 days (note lab values are used when field values are not available)) ] |
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- |
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Not applicable |
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Not applicable |
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Not applicable |
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NC |
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- |
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Deliquescent solids supplied in aqueous solution |
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Current |
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1997, introduced USA |
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- Luxembourg Industries (Pamol) Ltd
- UIM Agrochemicals (Australia)
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Usually supplied as an aqueous solution with a variety of application methods used including foliar sprays, soil drenches and root dips |
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Potassium phosphonates are commercially manufactured by neutralising phosphorous acid with potassium hydroxide in a controlled aqueous reaction. This process yields a mixture of mono- and di-potassium salts, primarily potassium phosphite which are collectively referred to as potassium phosphonates. The reaction is typically carried out under mild conditions to prevent decomposition of the phosphorous acid and to ensure complete neutralisation. Once the desired salt composition is achieved, the solution is filtered and concentrated, often forming a liquid formulation used directly in agricultural applications. |
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- |
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500000 |
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High |
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- |
- |
- |
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73 |
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- |
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Decomposes before boiling |
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- |
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180 |
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- |
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- |
- |
- |
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- |
- |
- |
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- |
- |
- |
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Insoluble |
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- |
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Regulatory data |
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- |
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1.65 |
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- |
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2.0 |
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- |
| PKa(2) = 6.59 |
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- |
- |
- |
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- |
- |
- |
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- |
- |
- |
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- |
- |
- |
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- |
- |
- |
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- |
- |
- |
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- |
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142 |
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Persistent |
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142 |
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Persistent |
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- |
- |
- |
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381 |
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Very persistent |
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- |
- |
- |
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- |
- |
- |
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EU dossier lab studies DT₅₀ range 88-196 days, DT₉₀ range 319-442 days |
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- |
- |
- |
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- |
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- |
- |
- |
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- |
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- |
- |
- |
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- |
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- |
- |
- |
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- |
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- |
- |
- |
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- |
- |
- |
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- |
- |
- |
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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. |
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- |
| Soil adsorption and mobility |
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10.7 |
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Moderately mobile |
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453.6 |
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EU dossier Kd range 3.1-18.96 mL g⁻¹, Koc range 228-972 mL g⁻¹, soils=5 |
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- |
- |
- |
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- |
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- |
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- |
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- |
| Known soil and groundwater metabolites |
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None
| Terrestrial ecotoxicology |
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> 5000 |
Rat |
Low |
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1270 |
Rat 90-day |
Low |
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> 400 |
Rat 2-yr |
Low |
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> 2250 |
Colinus virginianus as phosphonic acid |
Low |
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> 1335 |
Colinus virginianus as phosphonic acid |
- |
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149.04 |
Colinus virginianus NOEC |
Moderate |
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> 1000 |
Eisenia foetida as phosphonic acid |
Low |
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182.5 |
Eisenia foetida as phosphonic acid |
Low |
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Nitrogen mineralisation: Minor transient effects Carbon mineralisation: Minor transient effects |
Dose: up to 26.99 mg posphonic acid/kg soil 28 Day |
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- |
- |
- |
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- |
- |
- |
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- |
- |
- |
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- |
- |
- |
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- |
- |
- |
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> 145 |
as potassium phosphonates |
Low |
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- |
- |
- |
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- |
- |
- |
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- |
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- |
- |
- |
| - |
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- |
- |
- |
| - |
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- |
- |
- |
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- |
- |
- |
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- |
- |
- |
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- |
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- |
- |
- |
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- |
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- |
- |
- |
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- |
- |
- |
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> 20200 |
Aphidius rhopalosiphi as phosphonic acid |
Low |
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> 8080 |
Typhlodromus pyri as phosphonic acid |
Low |
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- |
- |
- |
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- |
- |
- |
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- |
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- |
- |
- |
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- |
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> 118 |
Oncorhynchus mykiss as phosphonic acid |
Low |
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100 |
Oncorhynchus mykiss as phosphonic acid |
Low |
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- |
- |
- |
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> 118 |
Daphnia magna as phosphonic acid |
Low |
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- |
- |
- |
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- |
- |
- |
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- |
- |
- |
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- |
- |
- |
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100 |
Chironomus riparius as phosphonic acid |
Low |
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- |
- |
- |
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- |
- |
- |
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- |
- |
- |
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146.7 |
Desmodesmus subspicatus as phosphonic acid |
Low |
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- |
- |
- |
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- |
- |
- |
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- |
- |
- |
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- |
- |
- |
| Regulatory Threshold Levels (RTLs) used to calculate Total Applied Toxicity (TAT) |
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80 |
Worst case of acute and chronic mammals |
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29.808 |
Worst case of acute and chronic birds |
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36.5 |
Worst case of acute and chronic earthworms |
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No data |
No data for non-target plants vegetative vigour and seedling emergence |
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2.9 |
Worst case of contact and oral honeybees |
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4040 |
Worst case of parasitic wasps and predatory mites |
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1.18 |
Worst case of temperate acute and chronic fish |
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1.18 |
Worst case of temperate acute and chronic aquatic invertebrates |
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14.67 |
Worst case of free-floating plants, rooted plants, acute and chronic algae |
| HUMAN HEALTH AND PROTECTION |
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High (class III) |
- |
- |
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> 5000 |
Rat |
Low |
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1270 |
Rat 90-day |
Low |
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> 400 |
Rat 2-yr |
Low |
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> 4000 |
Rat |
- |
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> 5.05 |
Rat |
- |
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- |
- |
- |
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2.25 |
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- |
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None allocated |
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- |
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- |
- |
- |
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5.0 |
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- |
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100 |
default |
- |
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- |
- |
- |
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Negligible risks identified for proposed uses |
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Negligible risks identified for proposed uses |
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- |
- |
- |
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| Carcinogen |
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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 ; E3 E = Unspecified genotoxicity type (miscellaneous data source) 3 = Negative |
XNo, known not to cause a problem |
| Reproduction / development effects |
Acetyl cholinesterase inhibitor |
Neurotoxicant |
| No data found |
XNo, known not to cause a problem |
No data found |
| Respiratory tract irritant |
Skin irritant |
Skin sensitiser |
| No data found |
?Possibly, status not identified |
?Possibly, status not identified |
| Eye irritant |
Phototoxicant |
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✓Yes, known to cause a problem |
No data found |
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No further information available |
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Not oxisiding or explosive Not expected to auto-ignite; Not highly flammable |
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Health: H302, H315, H320, H335 |
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Not listed (Not listed) |
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potassium phosphonates |
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| Record last updated: |
19/02/2026 |
| 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 |
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