Can titanium dioxide cause cancer?

Robust, scientific evidence shows that titanium dioxide is safe and does not cause cancer. Here’s what you need to know.

Titanium dioxide is a bright white pigment used across many different industries due to its unique and useful qualities. It is mostly used in everyday products such as paints, plastics, paper and inks. In some cases a nano form is used as an ingredient in products such as cosmetics and sunblock.

Applications using nano-grade titanium dioxide has led to some authorities questioning, as with all nanoparticles, whether titanium dioxide could be a carcinogen.

 

Current scientific evidence shows it safe to use products containing titanium dioxide:

  • Decades of industry and independent research has found no evidence of potential cancer risk to humans from titanium dioxide.

 

  • Scientific evidence has shown minimal or no effect from exposure to titanium dioxide, and European regulators have approved its safe use in food and sunscreen.

 

  • Studies that have linked titanium dioxide to cancer risk are based on a lung overload effect observed in rats, involving exposure to very high quantities of titanium dioxide by inhalation. Such high doses are higher than workers are exposed to on a daily basis and the lung action observed is not replicated in humans

 

Introduction

Titanium dioxide is a well-established and omnipresent natural substance. It has far-reaching capabilities and is manufactured all over the world.

It is used in many everyday items, such as paints, plastics, food, and cosmetics. Titanium dioxide – also known by its chemical name TiO2, or the food colourant E171 – has been assessed for safety by a large number of regulatory authorities and has consistently been found to be safe for all applications.

There has been recent speculation, particularly in French media, that it may cause cancer. Here are the facts.

colourful eye makeup

 

What IARC said about TiO2 and cancer

In 2006, the International Agency for Research on Cancer (IARC) concluded that there was inadequate evidence to state that titanium dioxide causes cancer in humans. A monograph detailing the findings was published in 2010.

IARC did conclude, however, that titanium dioxide is “possibly carcinogenic to humans by means of inhalation” (category 2b).

It found inadequate evidence in humans but sufficient evidence of cancer risk in animals. This conclusion was primarily based on evidence of it causing precancerous respiratory cysts in two chronic inhalation studies in rats, carried out in 1985 and 1995[1]. This finding has since been questioned given the limited evidence of an effect on humans.

The IARC assessment is solely based on these three rat studies carried out more than 20 years ago, under conditions that are not acceptable, according to the EU’s current testing guidelines.

It is generally recognised that rats are uniquely sensitive to the effects of “lung overload,” a condition that is not observed in humans.[2]

Other ‘possible carcinogens’ include bacon, pickled vegetables and aloe vera. During its history as an advisory group, IARC has assessed more than 980 substances and activities, and found hundreds to be potential risks.

 

What has changed since 2010?

In May 2016, the French national agency for food, environment and occupational health and safety (ANSES), proposed that titanium dioxide be classified as a category 1B substance, if inhaled. This classification means that something is presumed to have carcinogenic potential in humans.[3]

The proposal was submitted to the European Chemicals Agency (ECHA) to consider. A consultation was carried out, and ECHA’s Committee for Risk Assessment (RAC) reached a conclusion in June 2017. The committee concluded that there was insufficient evidence to classify titanium dioxide in category 1B.

Instead, it proposed that TiO2 met the criteria to be classified as a substance suspected of causing cancer when inhaled, a category 2 classification. Like the IARC statement, the RAC qualified the classification with a further statement that it does not “take into account the likelihood of exposure to the substance and therefore does not address the risks of exposure.”[4]

The evidence that has been assessed by authorities relates to studies carried out on animals.

At present, the RAC opinion about TiO2 has no immediate impact on how titanium dioxide can be used or is regulated.

Once the RAC opinion is documented and sent to the European Commission, the commission will decide whether to follow the RAC recommendation or not. This may lead to no change to regulation. Alternatively, the EC could update existing classification and labelling or consider new regulatory measures. There is no set timeline for a decision either way.

 

Low risk of inhalation or from consumption

Studies on the toxicology of substances should also take into account the principle of dosage, often referred to by the phrase: ‘The dose makes the poison.’ All chemicals – even water and oxygen – can be toxic to humans if consumed at high or extremely high doses.

Many animal studies on substances test the effects of a substance at high doses, which are not found in the real-world situations. The specific effects on animals may also not be replicated in humans, as in the case of the ‘lung overload’ observed in rats.

As the 2017 RAC opinion relates to inhalation of titanium dioxide, it has low relevance to food products. Here, TiO2 is incorporated in the finished product and there is almost no risk of inhaling it. Likewise, the TiO2 in finished products such as paints and plastics is either insoluble or solid and cannot be inhaled.

The European Food Standard Authority (EFSA) revaluated the use of TiO2 in food in 2016 and found that it was safe. The EFSA report stated that the absorption of orally administered TiO2 is extremely low:

“The Panel concluded that, based on the available genotoxicity database and the Panel’s evaluation of the data on absorption, distribution, and excretion of micro- and nanosized TiO2 particles, orally ingested TiO2 particles (micro- and nanosized) are unlikely to represent a genotoxic hazard in vivo [in a living organism].”[5]

“There seems to be a lot of misunderstanding about titanium dioxide,” says Kamilah Guiden, of the International Food Information Council (IFIC). She says titanium dioxide is safe to use, citing guidelines from the US Food and Drug Administration (FDA), which set a limit of 1 percent titanium dioxide for food.

“There is currently no indication of a health risk at this level of exposure through the diet,” she adds.[6]

Inhalation through other routes, such as paint or plastics, is also very unlikely due to the fact that TiO2 is fully bonded into the finished product.

 

Can titanium dioxide prevent cancer?

Titanium dioxide is deemed safe in all its consumer uses and no evidence has demonstrated a higher cancer risk for workers.

In fact, it can be used as an effective tool in preventing cancer. This finding is evident in its prominent use in sunscreens.

Because the particle size used in sunscreen is so small, it does not reflect visible light, but does scatter and absorb UV light, creating a transparent barrier to protect skin from the damaging rays emitted by the sun.

Titanium dioxide has been approved for use in sunscreens by both the European Commission in the EU and the FDA in the US.[7]

application of sunscreen

 

Safety of TiO2 in sunscreen

In Europe, the Scientific Committee on Consumer Safety (SCCS) says that titanium dioxide nanoparticles are safe as a UV filter in sunscreens if the concentration is 25 percent or below.[8] This applies to humans with healthy and intact, or even sunburnt, skin.

TiO2 nanoparticles can be photocatalysts, meaning they react with UV light. In sunscreen, particles are coated to prevent this, while maintaining their function as a UV filter.[8]

Groups that campaign for the use of safe ingredients across many products have also endorsed its use.

The Société Française de Dermatologie in France includes a reference to the use of titanium dioxide in sunscreen in its sun protection guidance.[9]

The Environmental Working Group (EWG), which rates products based on their health and environmental qualities, says titanium dioxide sunscreen lotions are “among the best choices.” Sunscreens using titanium dioxide score well in their ratings because they don’t break down in the sun and offer good protection from UVA rays.[10]

Meanwhile, the campaign group Safe Cosmetics also recommends its use in this way, saying: “Titanium dioxide makes a very effective sunscreen in creams and lotions, and is one of the safest options available.”[11]

 

Safe and valuable compound

Titanium dioxide can be safely used in a range of applications.

The low level of exposure and body of evidence showing this has no detrimental impact on health, such as a recent scientific study approving the use of TiO2 in food[5], demonstrates that the public does not face any known cancer risk from exposure to titanium dioxide.

Crucially, as a UV-blocker, it has important role in preventing cancer risk from sun exposure.