Chapter 10: Acids and alkalis · Part 2: Acids
Sulfamic acid
- Poison schedule (Australia)
The worst fact: it's a scheduled poison in Australia at any strength: Schedule 5 up to 10% and Schedule 6 above. It's "severely irritating to the eyes" and "reacts violently" with chlorine, giving a fire or explosion hazard.
Why brands use it: it's a solid acid that dissolves scale fast and gives off no fumes.
Take care if: you descale a kettle used for baby formula. Dutch poison specialists warn that kettle descalers can stay strongly acidic even diluted 10 times, so rinse the kettle out well before you use it. And never use it with bleach.
Comes from: urea reacted with sulfur trioxide and sulfuric acid.
Myth check: nil.
Contaminants: nil.
Fair to say: in water it's a medium-strength acid, weaker than hydrochloric acid.
Correct as of November 2026. What the badges mean
Sources
- Australian Government. Poisons Standard October 2026 (SUSMP), F2026L01327: sodium hydroxide, potassium hydroxide, alkaline salts, monoethanolamine, sulfamic acid, hydrochloric acid, acetic acid; Appendix B (sodium bicarbonate).
- Safe Work Australia. Hazardous Chemical Information System (HCIS): classifications for each chemical, and for ethylene oxide, carbon monoxide and acetaldehyde.
- ILO/WHO International Chemical Safety Cards: sodium hydroxide; sulfamic acid (0328).
- HSDB (US National Library of Medicine), via PubChem: production and impurity data for each chemical.
- Koppen et al. Descaling products and infants. Clin Toxicol 2022;60:71.
The full source list is at the end of Chapter 10.