Worth a closer look
Evidence key Strong Moderate Weak How we grade
Possible carcinogen Suspected genetic damage
- What it can be used for
- Cares for teeth and mouth (the functions the EU ingredient database, CosIng, lists for it; a product may use it for any of them)
- CAS number
- 10028-15-6
Why it’s flagged
Classified as a possible or suspected human carcinogen.
- EU classification Carc. 2. Source: EU CLP Regulation, Annex VI harmonized classification
IARC Group 2B means possibly carcinogenic to humans. EU Carc. 2 means suspected human carcinogen. These describe a hazard, not the risk at the amount in one product.
Classified as suspected of causing genetic defects.
- EU classification Muta. 2. Source: EU CLP Regulation, Annex VI harmonized classification
EU Muta. 2: suspected of causing genetic defects.
What the research says
- In a controlled chamber, the people themselves were the main thing reacting with indoor ozone: four seated adults removed about 60–65% of it, in two separate campaigns with men and with women, and their skin oils turned it into carbonyls such as 4-oxopentanal and 6-MHO. The same DTU chamber's protocol paper independently reproduced the ~60–69% removal in three more groups — teenagers and seniors as well as adults — across 26 experiments, and showed the sink is dermal (a breath-only control lost almost no ozone). Strong evidence. Wang 2024
- In the largest controlled test of its kind, 130 healthy young women breathing an indoor chemical mixture with and without ozone for 140 minutes showed no significant change in symptoms, lung function, attention or the stress hormone cortisol. Strong evidence. Fiedler 2005
- Four people in a clean, well-ventilated test room removed about two-thirds of the ozone coming in, confirmed in a second campaign that included women as well as men. Strong evidence. Zannoni 2021
- Scented cleaners react with ozone indoors and release bursts of tiny new particles; every study able to separate them found this. Strong evidence. Salonen 2024
- In a real test house, using a limonene-scented foam cleaner exactly as the label directed produced a burst of 45,000-150,000 tiny new particles per cubic centimeter within minutes, but only when ozone was in the air. Strong evidence. Rossignol 2013
- The moment ozone was added to pine-oil, citrus and air-freshener scent vapors in a lab chamber, a burst of new ultrafine particles formed immediately and grew within minutes into fine particles, reaching hundreds of micrograms per cubic meter. Strong evidence. Destaillats 2006
- Scent chemicals released by perfumes and scented products can react with ozone in indoor air to form new pollutants, including formaldehyde and fine particles. Strong evidence. Alblooshi 2025
- When scent chemicals from a pine-oil cleaner, an orange-oil degreaser and a plug-in air freshener met ozone in a lab chamber, about one formaldehyde molecule formed for every 3-5 ozone molecules they used up (yields of 20-30% in most tests). Strong evidence. Destaillats 2006
Each finding shows its evidence grade. See every graded fact or how we grade.
What this page can’t tell you
These lists describe what a substance can do, its hazard. The risk from one product depends on how much is in it and how you use it, and the label doesn’t say how much.
Not being on a list doesn’t make an ingredient safe. It may never have been assessed.
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Flagged the same way
Official lists checked September 2026. Spotted a mistake? Tell us.