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EC number: 629-716-7 | CAS number: 1211950-04-7
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data

Endpoint summary
Administrative data
Description of key information
Additional information
Diquat C16 -18 sorbs strongly to negatively charged surfaces like glassware, soil and sediment constituents. For three different soils, Kd values were observed ranging from: 1.6 * 10^4 to 1.9 * 10^5 L/kg. Biodegradation is considered to be the main removal mechanism of this substance. Most ready biodegradability tests are however hampered by the biocidal activity of these substances. In a SCAS (inherent ) test only partial degradation of the diquat C16 -18 was observed. Based on mass balance calculations (based on Carbon and Nitrogen consumption) considering the degradation of impurities and the ready biodegradability of the monoquat, the most likely metabolite structures are a diquat with an alkyl chain length of 4 or 2 carbons and an carboxylic acid at the end. Effluent tests with about 15 mg/L of this persistent metabolite present showed no effects in an acute daphnia test (Kean , 2010a) and an algae test (Kean, 2010b).
In summary: The parent diquat C16 -18 is quickly degraded into a metabolite which is considered to be persistent as a worst-case. The metabolite formed is more water soluble and where the parent is very toxic to aquatic organisms the metabolite formed has a low observed toxicity to aquatic organisms.
The half-life of the parent in the different environmental compartments is estimated to be strongly influenced by the bioavailability of the substance. No data is available for the determination of the half-life of diquat C16 -18 in soil or sediment. These values are therefore as a worst-case based on the readily biodegradability of the available fraction and the sorption data as determined in a sorption desorption test.
Table Summary of degradation rate constants of the parent compound, N,N,N’,N’,N’’-pentamethyl-N-C16-18 (even numbered) C18 unsat.-alkyl-1,3 -propanediammonium chloride in various (eco)systems.
(Eco)system |
Method |
|
Surface water (fresh) |
TGD default value |
15 days half-life |
Surface water (fresh) sediment |
TGD default value |
30000 days half-lifea |
Marine water |
TGD default value |
50 days half-life |
Marine water sediment |
TGD default value |
30000 days half-lifea |
Soils |
TGD default value |
30000 days half-lifea |
Degradation in sewage treatment plants |
Determined in bioreactors |
>99.9% removal primarily by biodegradation |
aHalf-life of the fraction dissolved in the water phase is expected to be in the order of a few days.
Diquat C16 -18 has a short predicted half-life in air but because there are no important releases into the atmosphere and volatilisation is expected to be negligible, this removal mechanism is thought to be of low relevance.
Diquat C16 -18 does not contain hydrolysable covalent bonds. Cleavage of a carbon-nitrogen bond under environmental conditions is only possible with a carbonyl group adjacent to the nitrogen atom. Degradation of diquat C16 -18 through hydrolysis is therefore not considered.
Direct photolysis of diquat C16 -18 in air/water/soil will not occur, because it does not absorb UV radiation above 290 nm. Photo transformation in air/water/soil is therefore assumed to be negligible.
Standard OECD 305 tests are technically not feasible with these strongly sorbing easily degradable substances. In addition is the route of exposure in a standard OECD 305 test unrealistic for these substances because the substance will either be sorbed or biodegraded. The bioaccumulation potential of diquat C16 -18 was therefore assessed based on a measured log Kow. This log Kow of 0 is measured in an OECD 123 slow-stirring test. This low measured Log Kow indicates a low bioaccumulation potential.
The predicted low bioaccumulation potential is supported by the low acute to chronic ratio observed in the long-term daphnia test.
The daphnia reproduction test result shows that at 810 μg/L all parental daphnids were immobile within two days, without reproduction, while at the next concentration of 270 µg/L there is no detrimental effect on reproduction for the surviving daphnids when compared to the control. These observations result in the derivation of a NOEC of 270 µg/L for reproduction resulting in a low acute-to-chronic ratio. A low acute-to-chronic ratio is indicative of a non-specific mode of action and is often associated with not systemic effects. This observation is consistent with the known effects of cationic surfactants on aquatic organisms, where toxicity is associated with physical binding to respiratory membranes. This explains the steep concentration curves seen and the lack of intermediate chronic effects on reproduction.
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