Chapter 7: Disinfectants and antibacterials · Part 2: Alcohols
Isopropyl alcohol
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The worst fact: it's about twice as toxic as ethanol if swallowed, and the main effect is depressing the brain and breathing. Poisoning handbooks record deep coma after sponging the skin with it.
Why brands use it: it kills bacteria slightly better than ethanol and evaporates fast.
Take care if: you have young children, or are near a flame: 75% IPA catches fire at 19°C. Australia classes it as "Causes serious eye irritation; May cause drowsiness or dizziness; Highly flammable liquid and vapour".
Comes from: propylene (from petroleum) reacted with water.
Myth check: "99% is stronger": no. Mixtures with water kill germs better than pure alcohol, and IPA doesn't kill non-enveloped viruses such as enteroviruses.
Contaminants: nil.
Fair to say: it isn't classifiable as a cancer risk, and the WHO's second hand-rub recipe is 75% IPA.
Correct as of November 2026. What the badges mean
Sources
- Safe Work Australia. Hazardous Chemical Information System (HCIS): classifications for each chemical, and for benzene and benzyl chloride.
- US CDC. Guideline for disinfection and sterilization (2008); Hand sanitizer guidelines (2024).
- WHO. Guide to local production of WHO-recommended handrub formulations (2010).
- HSDB (US National Library of Medicine), via PubChem: manufacturing, toxicity and impurity data.
The full source list is at the end of Chapter 7.