Titanium Dioxide and Cancer

This page is for anyone who has seen titanium dioxide on a label or works with it. It explains why IARC listed it as a possible carcinogen, which exposures that finding is about, and how sunscreen and food fit in.

Titanium dioxide is a bright white powder. Its chemical formula is TiO2. It scatters light very well. A small amount makes a product look opaque and very white. That is why it is used in paint, plastics, some sunscreens, and some foods.

Two things decide whether any of that matters for cancer risk. The first is the physical form. A fine dust floating in the air acts nothing like the same pigment locked inside dried paint. The second is the route into the body. Breathing a dust is not the same as rubbing a cream on your arm. It is not the same as swallowing a trace amount in frosting.

The International Agency for Research on Cancer (IARC) is the cancer research arm of the World Health Organization. It reviews substances in working groups. Each group of agents gets its own published volume. TiO2 was reviewed in Volume 93, published in 2010, alongside carbon black and talc.

The working group wrote three separate findings. On people: "There is inadequate evidence in humans for the carcinogenicity of titanium dioxide." On animals: "There is sufficient evidence in experimental animals for the carcinogenicity of titanium dioxide." The overall call: "Titanium dioxide is possibly carcinogenic to humans (Group 2B)."

Group 2B is the weakest positive box IARC uses. "Inadequate evidence" does not mean the studies found safety. It means the human studies were too few, or too mixed, to settle the question either way.

IARC reviewed titanium dioxide together with carbon black and talc because all three are poorly soluble particles. Animal studies had linked them to cancer of the respiratory tract after inhalation. The working group weighed human studies, animal studies, and evidence on how the particles act in the body.

The human evidence was graded inadequate. That means the studies were too few or too mixed to settle the question. The animal evidence was graded sufficient. On the mechanism evidence, the group found it "was not strong enough to warrant a classification other than Group 2B."

The open question is how far the animal findings carry over to people who breathe dust at work.

If you handle this powder for a living, a federal rule applies. OSHA sets a legal permissible exposure limit (PEL), the most a worker may breathe on average across a shift. For titanium dioxide as total dust it is 15 milligrams per cubic meter of air (OSHA Table Z-1). The NIOSH research institute publishes its own guidance on titanium dioxide at work. We could not open it for this check, so we do not quote its figures here. Ask your employer's safety office for current guidance.

Basic dust control is the usual way to cut exposure:

• Closed transfer of powder.
• Exhaust hoods at bagging and mixing points.
• Wet cleanup instead of dry sweeping.
• Respirators where dust cannot be controlled another way.

Nothing in the 2010 review rested on skin contact. Mineral sunscreens use TiO2 because it sits on the skin surface and scatters ultraviolet light. Skin is not lung tissue, and a cream is not an airborne dust. The one product format where breathing is even plausible is a loose powder or a spray. Those are worth pointing away from your face as you apply them. If you are weighing sun safety against chemical worry, our page on sunscreen covers what these products do and do not do.

Food is governed by a specific rule rather than a general opinion. In the United States, TiO2 is a color additive listed at 21 CFR 73.575. The rule caps how much may be used. The quantity "does not exceed 1 percent by weight of the food." It also sets purity limits the pigment must meet. Those include:

• At least 99.0 percent TiO2 after drying.
• Lead no higher than 10 parts per million.
• Arsenic and mercury no higher than 1 part per million each.
• Antimony no higher than 2 parts per million.

Other countries have made different calls on food use. That is why headlines from Europe and the United States can disagree while both describe real rules.

One more piece of context. The National Toxicology Program's 15th Report on Carcinogens lists substances known or reasonably anticipated to cause cancer in humans. TiO2 is not among its listings.

A carcinogen listing answers a narrow question. Can this substance cause cancer under some conditions? It does not answer how likely cancer is for you at the exposure you actually have. Those are two different questions. Our page on hazard versus risk works through why a Group 2B listing and a personal risk estimate are not the same thing. If you want the general framework first, start with what a carcinogen is.

For TiO2, the honest summary is short. The exposure that earned the listing is years of breathing fine powder, mostly at work, at levels no shopper meets. The consumer exposures were not the basis of the finding. That includes paint on a wall, a mineral sunscreen, and a trace in food. If you work with the powder, dust controls and your workplace exposure limits are where your attention belongs.

• IARC Monographs Volume 93 — Carbon Black, Titanium Dioxide, and Talc (2010)
• IARC Monographs Volume 93, full text on NCBI Bookshelf
• 21 CFR 73.575 — Titanium dioxide (govinfo)
• OSHA Annotated Permissible Exposure Limits, Table Z-1
• NTP — 15th Report on Carcinogens