Sodium selenite
CAS 10102-18-8 · EC 233-267-9 · Na2O3Se
Also known as disodium selenite
No UK Poisons Act entry for selenium compounds found on the GOV.UK list.
Handle chemistry safely
Wear gloves and eye protection, work with good ventilation, and read the supplier’s safety data sheet before use. Hazard information here is a summary, not a replacement for it. Dispose of all photographic chemistry correctly, in line with local laws and your local authority’s guidance. Never mix waste solutions, and check the supplier’s safety data sheet before disposing of anything.
Hazards
Official EU classification (harmonised under CLP Annex VI).
Signal word: Danger
Acute toxicity · Hazardous to the environment
- H331 Toxic if inhaled.
- H300 Fatal if swallowed.
- H317 May cause an allergic skin reaction.
- H411 Toxic to aquatic life with long lasting effects.
- EUH031 Contact with acids liberates toxic gas.
Photographic uses
- selenium toner (commercial toners contain selenium compounds; raw-chemical use uncommon)
Sources
- ECHA CHEM substance record: Sodium selenite (100.030.230)
- ECHA CHEM – C&L Inventory (harmonised CLP Annex VI and notified classifications) and legal obligations (chem.echa.europa.eu APIs: /api-cnl-inventory/harmonized|industry, /api-obligation-substance/v1)
- Supplying explosives precursors and poison substances: list of chemicals (supplying-explosives-precursors/list-of-chemicals (updated 3 July 2026))
Checked October 2026.