Chapter 9: Solvents and hydrocarbons · Part 2: Glycols and helpers
Sodium xylene sulfonate
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The worst fact: hydrotropes like SXS are used at up to 11.9% in rinse aids and 6% in hard-surface cleaners (European industry data, 2005), and they're slight-to-moderate eye irritants. Australia classes it as "Causes serious eye irritation".
Why brands use it: it keeps ingredients that don't mix dissolved, stops liquids separating in the cold, and adjusts thickness.
Take care if: you get the neat product in your eyes: rinse with water for several minutes.
Comes from: xylene treated with sulfuric acid (oleum), then neutralised with caustic soda.
Myth check: "It's xylene": no. The xylene ring is chemically locked to a sulfonate group, making a salt that dissolves in water and doesn't evaporate.
Contaminants: nil.
Fair to say: two-year skin studies in rats and mice found "no evidence of carcinogenic activity", it breaks down readily, and an industry risk assessment found household exposure to hydrotropes over 500,000 times below the level of concern.
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, propylene oxide, epichlorohydrin, benzene, 1,3-butadiene-containing butane and 1,2-dichloroethane. Workplace exposure standards (amended November 2025) and workplace exposure limits (July 2025). Labelling of workplace hazardous chemicals code of practice (2015). Trichloroethylene health monitoring guide.
- US National Toxicology Program. Technical Report 464: sodium xylenesulfonate (1998); Report on Carcinogens, 15th edition; NTP-CERHR monograph on propylene glycol (2004).
- HSDB (US National Library of Medicine), via PubChem: manufacturing, use and impurity data.
- HERA. Propylene glycol n-butyl ether (2005); hydrotropes (2005).
The full source list is at the end of Chapter 9.