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EC number: 610-672-2 | CAS number: 51503-61-8
- 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
Link to relevant study record(s)
Description of key information
No bioaccumulation potential
Key value for chemical safety assessment
- Bioaccumulation potential:
- no bioaccumulation potential
Additional information
Introducion
The pure active substance, phosphorous acid (H3PO3), is phytotoxic, due to its acidic character. Ammonium ions are used for neutralization of the acid. The registered substance is an ammonium salt of phoshorous acid:
(NH3)2HPO3
One hydrogen atom is bound to the phosphorus with a covalent bond and does not dissociate. Therefore, only two hydrogen atoms can be replaced with a cation.
The part of the molecule with the biological activity is the phosphite ion (HPO32-),
Chemistry of phosphorous acid
The chemistry of phosphorous acid, the acid from which the phosphite ion is derived, is important for understanding the chemistry, the definition of the characteristics, as well as the testing and evaluating of the product. Phosphorous acid has two tautomers (i .e., two molecular configurations, which rapidly convert between each other):
The equilibrium favours the phosphonic acid tautomer , in which the phosphorus is in a pentavalent form [ i.e., (OH)2HPO], due to the strength of the phosphoryl group (P=O), thus under most circumstances the predominant tautomer is the phosphonic acid (RICKARD 2000).
The corresponding pKa-values for the dissociation of the hydrogen ions are:
pKa1= 1.3
pKa2 = 6.7
The low oxidation level of the phosphorus atom in the phosphorous acid, compared to phosphoric acid (H3P04), indicates a high reduction potential of phosphorous acid. However, phosphite reacts slowly with many oxidants (OHASHI 1972), and is surprisingly stable when exposed to atmospheric oxygen (ROBERTSON & BOYER 1956b). Thus, the proposed product is stable in storage and transport, and in dilutions prior to application.
Phosphorous acid forms two kinds of salts: easily water-soluble primary salts are formed with monovalent metals, such as alkali me als (potassium, sodium ), and forms soluble secondary salts with heavy metals, e.g. iron (HOLLEMAN-WIBERG 1971). A basic discussion of the chemistry of lower oxy-acids of phosphorus, including phosphorous acid, is given by WAZER (1958), COTTON & WILKINSON (1966), OHASHI (1964 & 1972).
ADME
Study with sodiumphosphite
Greger JL, Kaup S.M., Behling A.R. (1991); Calcium, Magnesium and phosphorus Utilization by rats fed sodium and potassium salts of various inorganic anions. J. Nutr. 121: 1382-1388.
Greger et al. (1991) showed that ingestion of inorganic anions increased urinary escretion of these anions regardless of whether the anions were ingested as sodium or potassium salts. The cations (sodium or potassium) had no effect on the toxicokinetics of the anions. Thus studies of the toxicokinetics of sodium phosphite may be used to make inferences to potassium phosphite.
When sodium phosphite- 32P was orally administered to male and female rats phosporous acid was mainly excreted in the urine (59-65%). A smaller amount (30-33%) was found in the faeces. Only minor amounts (1.2%) of the ad ministered radioactivity were found in the body 72 hours after cessation of dosing. The highest amount found in the spleen.
The level of radioactivity in blood reached a maximum 1 to 2.5 hours after the initial dosing. The disappearance of radioactivity from the blood seems to occur in two stages, first a rapid one (Tl/2-1-3 hours) then a much slower one. (PELFRENE 1982a).
In conclusion, phosphite is excreted via urine without undergoing metabolism . It does not cause residues of concern in tissues of exposed mammals.
Acute toxicity studies
No adverse affect, no systemic toxicity, no accumulation in organs has been reported during hystopathological examination after acute toxicity studies performed on oral and dermal exposure
Repeated dose studies
No adverse affect, no systemic toxicity, no accumulation in organs has been reported during hystopathological examination after repeated dose toxicity studies performed on oral exposure
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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