Chapter 10: Acids and alkalis · Part 2: Acids
Citric acid
No badge
The worst fact: eye irritation is its main hazard. And the citric acid in cleaners doesn't come from lemons: about 99% of world production is made by microbes, mostly a mould, Aspergillus niger, fed on sugar.
Why brands use it: it dissolves limescale and rust, softens water, and is low in toxicity. Surface cleaners can contain up to 30%.
Take care if: you have marble, limestone or travertine, or for your eyes.
Comes from: sugar or molasses fermented by Aspergillus niger mould.
Myth check: "Natural means harmless": not quite. It's mild, but Australia classes it as an eye and skin irritant. Claims that the mould-made version causes illness rest on four case reports, and the authors say they can't prove it.
Contaminants: nil.
Fair to say: it's a food additive with no set limit on intake, and lemon juice is 5 to 7% citric acid. It isn't suspected of causing cancer or birth defects.
We use this ingredient. It's in our Laundry Powder, Dishwasher Powder, Mould Remover Wall Cleaner and Curtain Mould Shield. In the Dishwasher Powder it handles the rinse, so no rinse aid is needed.
Correct as of November 2026. What the badges mean
Sources
- Safe Work Australia. Hazardous Chemical Information System (HCIS): classifications for each chemical, and for ethylene oxide, carbon monoxide and acetaldehyde.
- HERA. Citric acid (2005).
- Sweis IE, Cressey BC. Potential role of the common food additive manufactured citric acid in eliciting significant inflammatory reactions. Toxicol Rep 2018;5:808-812.
The full source list is at the end of Chapter 10.