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Chapter 11: The supporting cast · Part 6: Stabilisers

Boric acid and borax

  • Poison schedule (Australia)
Also called
sodium borate, sodium tetraborate, borax decahydrate, orthoboric acid
Found in
liquid laundry detergent (enzyme stabiliser); borax sold pure as a laundry booster and multi-purpose cleaner

The worst fact: in a hospital nursery case reported in 1964, 11 newborn babies were fed formula accidentally made up with 2.5% boric acid. Five died.

Why brands use it: it holds the protease enzyme dormant in the bottle until it's diluted in the wash.

Take care if: you're pregnant or trying for a baby, or have young children. Australia classes both as "May damage fertility. May damage the unborn child." Boric acid and its salts are a Schedule 5 Poison above 6% (calculated as boric acid), so pure borax carries a CAUTION and "DO NOT SWALLOW" label. Pure borax is sold in Australia as a multi-purpose cleaning agent, and one Australian borax safety data sheet warns that swallowing 5 to 10 g can cause shock and death in children. Doctors have reported hand dermatitis and chemical burns in children from homemade borax slime.

Comes from: mined borate ores. Boric acid is made by adding sulfuric or hydrochloric acid to borax.

Myth check: "It's a natural mineral, so it's safe": mined doesn't mean harmless. "Borax and boric acid used in powders and ointments have resulted in serious poisonings and death." Since 17 December 2022, the EU has barred cleaners with 0.3% or more of boric acid or borax from sale to the general public.

Contaminants: nil.

Fair to say: an Australian Government risk assessment (2008), reported by the chemicals regulator, found laundry products with 1% and dishwashing liquids with 2% boric acid "not of any significant human health concerns"; absorption through intact skin is negligible.

Correct as of November 2026. What the badges mean

Sources

  • Australian Government. Poisons Standard October 2026 (SUSMP), F2026L01327: boric acid; sodium stannate; formic acid; Appendix B (dimeticone).
  • Safe Work Australia. Hazardous Chemical Information System (HCIS): classifications for calcium chloride, boric acid, borax, and for N-vinylpyrrolidone, vinyl acetate, ethylene oxide, 1,4-dioxane, hydrazine, aniline, p-toluidine, styrene, chloromethane, carbon monoxide and octamethylcyclotetrasiloxane (D4).
  • NICNAS/AICIS. IMAP Tier II assessments: boric acid and borates; titanium dioxide (2016); octamethylcyclotetrasiloxane (D4); decamethylcyclopentasiloxane (D5).
  • European Union. Regulation (EC) 1333/2008 Annex V; Regulation (EU) 231/2012 (food additive specifications); Regulation (EU) 2022/63 (E171); Regulation (EU) 1297/2014 (detergent capsules); Regulation (EC) 790/2009 and Delegated Regulation (EU) 2021/849 (borates); Regulation (EU) 109/2012; Regulation (EU) 2023/2055 (microplastics); Regulation (EU) 2024/1328 (D4, D5, D6); Regulation (EC) 1223/2009 (cosmetics) Annexes III and IV.
  • US EPA. Denial of TSCA petition on polyvinyl alcohol, 88 FR (21 April 2023); Safer Choice Ingredient List.
  • HSDB (US National Library of Medicine), via PubChem: manufacturing, use and impurity data.
  • HERA. Protease (subtilisin) (2007).
  • Wong LC et al. Boric acid poisoning: report of 11 cases. CMAJ 1964;90:1018-1023.
  • Slime-related hand dermatitis in children. CMAJ 2019.

The full source list is at the end of Chapter 11.