Chapter 4: Bleaches and brighteners · Part 2: Chlorine bleaches (and ammonia)
Sodium hypochlorite
- Poison schedule (Australia)
- Contaminant risk
The worst fact: mixed with other cleaners, it gives off chlorine or chloramine gas. US poison centres recorded 85,104 exposures to those gases from 2015 to 2022, rising 61%. 85% happened at home. Most were mild, but 26 people died. In NSW, bleach was the second most common product behind poison calls in 2014–15 (1,129 calls), and the most common for adults.
Why brands use it: it kills a broad range of germs fast, and it's cheap.
Take care if: you have asthma, have children, or use it most days. In a European study, adults who used bleach 4 or more days a week had more chest symptoms. In another, children in homes that used bleach had more flu and repeat tonsillitis. Both are links, not proof. Never mix it with anything but water.
Comes from: chlorine bubbled into cold caustic soda. Both come from salt water split by electricity.
Myth check: "Bleach kills mould, so it fixes mould": half true. It does kill mould, but the US Environmental Protection Agency doesn't recommend bleach for routine mould cleanup: some spores always remain, and they won't grow once the damp is fixed. It also says "dead mold may still cause allergic reactions in some people", so mould has to be removed, not just killed. Australian health advice says household detergent or white vinegar is often enough. And bleach doesn't clean: dirt uses it up, so clean the surface first.
Contaminants: chlorate and bromate. Bleach slowly breaks down into salt and chlorate, faster when it's old or kept warm. In a Spanish study of water-treatment hypochlorite, the median chlorate level was 20,462 mg/L, and 33 of 40 samples also held bromate (median 1,022 mg/L). Bleach products can also react with soap and surfactants to put chloroform (up to 24.6 µg/m³) and carbon tetrachloride (up to 459 µg/m³) into indoor air while you clean. They're unlikely to matter in a well-made product, but it's a factor you can't see on the label. Store bleach somewhere cool and dark, and buy small bottles.
Fair to say: the World Health Organization recommends dilute bleach (0.1%) for disinfecting surfaces. Small accidental sips of household bleach usually cause only minor effects. Makers leave extra caustic soda in bleach to slow its breakdown, and that's part of why it burns skin (see Chapter 10). In Australia, liquid bleach above 4% available chlorine is a Schedule 5 Poison, and above 20% a Schedule 6 Poison, unless its pH is below 11.5. Between 2 and 4% it's unscheduled only if the label says "WARNING – Ensure adequate ventilation when using. Vapour may be harmful. May give off dangerous gas if mixed with other products".
Correct as of November 2026. What the badges mean
Sources
- Australian Government. Poisons Standard October 2026 (SUSMP), F2026L01327: chlorinating compounds, dichloroisocyanuric acid, hydrogen peroxide, sodium percarbonate, peracetic acid, ammonia.
- Safe Work Australia. Hazardous Chemical Information System (HCIS): classifications for each chemical, and for borax. hcis.safeworkaustralia.gov.au
- ACCC. Analysis of consumer product related calls to the NSW Poisons Information Centre, June 2014 to May 2015 (2016). productsafety.gov.au
- Better Health Channel (Victorian Department of Health). Mould removal at home. betterhealth.vic.gov.au
- NHMRC. Australian Drinking Water Guidelines: chlorate.
- US EPA. A Brief Guide to Mold, Moisture, and Your Home (EPA 402-K-02-003); Safer Choice Safer Chemical Ingredients List; Chemical Safety Alert: safe storage and handling of swimming pool chemicals (2001).
- UK Health Security Agency. Sodium hypochlorite: general information (2025); Ammonia: general information (2024).
- World Health Organization. Cleaning and disinfection of environmental surfaces in the context of COVID-19 (2020); Chlorine chemical fact sheet (2022).
- ESR (New Zealand). Health risk assessment: household bleach (2015).
- Atalla et al. Chlorine and chloramine gas exposures reported to US poison centers, 2015–2022. Clin Toxicol 2024;62(9):589-595.
- Zock JP et al. Domestic use of hypochlorite bleach, atopic sensitization, and respiratory symptoms in adults. J Allergy Clin Immunol 2009;124:731-738.
- Casas L et al. Domestic use of bleach and infections in children. Occup Environ Med 2015;72:602-604.
- Odabasi M. Halogenated volatile organic compounds from the use of chlorine-bleach-containing household products. Environ Sci Technol 2008;42:1445-1451.
The full source list is at the end of Chapter 4.