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Diss Factsheets
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EC number: 240-778-0 | CAS number: 16721-80-5
- 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
Abiotic degradation
Na2S and NaHS are not expected to be released to the air as such because of their low vapour pressure. However, in case H2S is formed, H2S may be released to the air. In the atmospheric compartment, sulfur compounds such as H2S will be oxidized to SO2 and, eventually, to sulfate compounds.
When Na2S or NaHS are released to the aquatic compartment, the substances will hydrolyze immediately and a pH dependent equilibrium will be established between H2S, HS- and S2-. However, in aerobic environments, the dissolved sulfide will be oxidized to - eventually - sulfate. In anaerobic environments (e.g., organic-rich sediments) H2S formation will be favoured and no oxidation will occur. However, in these kinds of environments, the dissolved sulfide may be depleted through precipitation with metals. In view of environmental hazard assessment, it should however be kept in mind that typical organisms living in natural reducing environments are often well adapted to living in the fluctuating presence of H2S.
Except in waterlogged and/or highly organic soils, released sulfides are expected to be oxidized relatively rapidly. In soils with reducing conditions, H2S formation will be favoured and similar transformation/removal processes as in sediments will occur. This also holds for deeper layers of well drained soils.
Biodegradation
Biodegradation is not deemed relevant for inorganic compounds. However, it should be kept in mind that any sulfur released to the environment will enter the natural sulfur cycle in which both oxidation and reduction reactions are mediated through abiotic as well as biotic processes. Sulfur oxidizing and reducing microorganisms are omnipresent and determine the predominant state of the present sulfur depending on the prevalent conditions.
Environmental distribution
Release to the aquatic environment will be the most relevant route of release for Na2S and NaHS. As mentioned above, the substances will be hydrolyzed immediately upon contact with water and depending on the conditions reduced sulfides will stay present in the system or become oxidized to - eventuallly - sulfate. At the moment of release, the sulfur added to the environment enters the natural sulfur cycle and industrially released sulfur will become indistinguishable from naturally present or - overall - formerly present sulfur. Consequently, the environmental distribution of these compounds will be driven by the same reactions driving the natural sulfur cycle. For a thorough description of the sulfur cycle one can refer to the review of Brown (1982).
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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