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EC number: 231-957-4 | CAS number: 7782-49-2
- 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
Ecotoxicological Summary
Administrative data
Hazard for aquatic organisms
Freshwater
- Hazard assessment conclusion:
- PNEC aqua (freshwater)
- PNEC value:
- 2.67 µg/L
- Assessment factor:
- 3
- Extrapolation method:
- sensitivity distribution
- PNEC freshwater (intermittent releases):
- 5.5 µg/L
Marine water
- Hazard assessment conclusion:
- PNEC aqua (marine water)
- PNEC value:
- 2 µg/L
- Assessment factor:
- 3
- Extrapolation method:
- sensitivity distribution
STP
- Hazard assessment conclusion:
- PNEC STP
- PNEC value:
- 1 500 µg/L
- Assessment factor:
- 10
- Extrapolation method:
- assessment factor
Sediment (freshwater)
- Hazard assessment conclusion:
- PNEC sediment (freshwater)
- PNEC value:
- 8.2 mg/kg sediment dw
- Extrapolation method:
- equilibrium partitioning method
Sediment (marine water)
- Hazard assessment conclusion:
- PNEC sediment (marine water)
- PNEC value:
- 6.2 mg/kg sediment dw
- Extrapolation method:
- equilibrium partitioning method
Hazard for air
Air
- Hazard assessment conclusion:
- no hazard identified
Hazard for terrestrial organisms
Soil
- Hazard assessment conclusion:
- PNEC soil
- PNEC value:
- 0.044 mg/kg soil dw
- Assessment factor:
- 10
- Extrapolation method:
- assessment factor
Hazard for predators
Secondary poisoning
- Hazard assessment conclusion:
- PNEC oral
- PNEC value:
- 1 mg/kg food
- Assessment factor:
- 1
Additional information
General discussion
In the assessment of the ecotoxicity of selenium metal, a read-across approach is followed based on all relevant and reliable information available for inorganic Se compounds. This grouping of selenium compounds for estimating their properties is based on the assumption that properties are likely to be similar or follow a similar pattern as a result of the presence of the common selenium ion.
This assumption can be considered valid when:
i) differences in solubility among Se compounds do not affect the results for ecotoxicity (i.e. toxicity occurs below the solubility limit),
ii) ecotoxicity is only affected by the selenium-ion and not by the counter ions, and
iii) after emission to the environment, the various Se compounds do not show differences in speciation of selenium in the environment or differences in speciation do not affect toxicity.
In order to correct for differences in solubility among Se compounds, all reliable data on ecotoxicity selenium to aquatic organisms were selected based on measured dissolved selenium concentrations. It is indeed assumed that toxicity is not controlled by the total concentration of an element, but by the bioavailable form. No evidence is available on the bioavailable form of selenium, but as a conservative approximation, it can be assumed that the total soluble selenium pool is bioavailable. For soils, data were only available for the soluble sodium selenite and sodium selenate salts (solubility > 1g/L) and therefore no effect of solubility on the toxicity was expected.
The reliable ecotoxicity results were all mainly derived for sodium selenite (Na2SeO3) and sodium selenate (Na2SeO4), but some reliable data are also available for H2SeO3, SeO2, seleno-methionine and seleno-cysteine. There is no concern on the effect of the counter-ions (Na+) in the concentration ranges tested.
The data for organic Se compounds (Se-methionine and Se-cysteine) were not taken into account for the assessment of direct effects of selenite to aquatic or terrestrial organisms because there is some concern on different biochemical behaviour of this selenium containing amino acid compared to inorganic Se compounds. However, because inorganic Se can be transformed into this organic form in the environment, data for seleno-methionine and seleno-cysteine are included for the assessment of secondary poisoning (through PNECoraland bioconcentration factors).
For aquatic organisms, the comparison in toxicity among the various inorganic Se substances (H2SeO3, Na2SeO3, SeO2or Na2SeO4) did not yield consistent or significant differences. Therefore, results for all these substances were used in a read-across approach. In contrast, for soils a clear difference in toxicity was observed between selenite and selenate, with selenate showing significantly higher toxicity to terrestrial invertebrates (Somogyi et al. 2007 & 2012) and plants (Cartes et al., 2005; Carlson et al., 1991). This is consistent with the lower adsorption and resulting higher bioavailability of selenate in soil compared to selenite. Therefore, only the available reliable results for toxicity of selenite to terrestrial organisms (plants, invertebrates and micro-organisms) are taken into account for the hazard assessment of sodium selenite in soils.
Selenium is chemically related to sulphur and can exist in a multitude of different oxidation states from -2 to +6 and in both organic and inorganic forms. Under conditions commonly found in oxic fresh waters (i.e., pH between 5 and 9; redox potential [Eh] between 0.5 and 1 V), the hexavalent oxidation state is predicted to be the most prevalent (Takeno, 2005). However, tetravalent selenium also exists under some conditions (low pH, low redox potential).
No information is available on the speciation of the selenium compounds of interest upon dissolution in water and on the redox speciation of the selenium compounds during the various tests available. Some measured data were found on speciation of selenium in the environment. These results confirm that hexavalent Se dominates in most surface waters, while elemental Se and organic Se species dominate in sediments (Zhang and Moore, 1996; Van Derveer and Canton, 1997). Based on limited information available, the environmental conditions are expected to largely control the (redox) speciation of selenium upon dissolution in water, regardless of the Se compound added. However, as mentioned above, a significant difference in adsorption of selenite (SeO32-) and selenate (SeO42-) to soil was observed, with lower adsorption for selenate (median log KDof 0.87 L/kg dry weight) compared to selenite (median log KDof 1.73 L/kg dry weight).
In conclusion, all available reliable data for inorganic selenium compounds were used in a read-across approach for aquatic toxicity, except for toxicity to aquatic microorganisms. Only data for selenite were selected for toxicity to aquatic microorganisms and terrestrial organisms (plants, invertebrates and micro-organisms). For toxicity to above-ground organisms (birds, mammals and reptiles) and fish via diet all Se compounds were taken into account, including Se containing amino acids seleno-methionine and seleno-cysteine. All results for ecotoxicity of Se are expressed based on elemental selenium concentrations.
See also read-across justification document attached to IUCLID section 13.
Conclusion on classification
- The lowest relevant and reliable acute fish LC50for soluble inorganic selenium substances is 2060 µg Se/L;
- The lowest relevant reliable acute invertebrate E(L)C50for soluble inorganic selenium substances is 550 µg Se/L;
- The lowest relevant reliable algal E(L)C50for soluble inorganic selenium substances is 240 µg Se/L. Algae and invertebrates are markedly more senstive to dissolved Se than fish. The ERVacutefor selenium is based on algal data and is 240 µg Se/L.
- The lowest relevant and reliable chronic fish NOEC for soluble inorganic selenium substances is 10 µg Se/L
- The lowest relevant and reliable chronic invertebrate NOEC for soluble inorganic selenium substances is 70 µg Se/L
- The lowest relevant and reliable algal NOEC for selenium soluble inorganic selenium substances is 197 µg Se/L
Reliable acute and chronic toxicity data are available for effect of inorganic selenium compounds on the three trophic levels.
The acute classification is based on the lowest value that was identified for any of the three trofic levels that are taken into account:
Algae and invertebrates are markedly more senstive to dissolved Se than fish. The ERVacutefor selenium is based on algal data and is 240 µg Se/L
The chronic classification is based on the lowest value that was identified for any of the three trophic levels that are taken into account:
Fish were the most sensitive trofic level upon long-term exposure and determined the ERVchronicfor selenium of 10 µg Se/L.
Taking into account the solubility of Selenium metal there is no need to classify this substance for the environment. Selenium metal, however, has a harmonised classification for the environment (Aq.Chronic Cat.4), and this classification is currently applied.
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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