Titanium dioxide: toxic or safe?

Titanium dioxide is the subject of a new controversy, but it is a substance as old as the earth itself. It is one of the top fifty chemicals produced worldwide. It is a white, opaque, natural mineral found in two main forms: rutile and anatase. Both forms contain pure titanium dioxide which is bound to impurities. Titanium dioxide is chemically processed to remove these impurities, leaving the pure white pigment available for use. Titanium dioxide has a variety of uses, as it is odorless and absorbent. This mineral can be found in many products, from paints to food and cosmetics. In cosmetics, it serves several purposes. It is a white pigment, opacifying and sunscreen. Concerns have arisen from studies that have targeted titanium dioxide as a carcinogen and photocatalyst, thus creating fear in consumers. But are these claims true? What does the investigation on these allegations confirm? Would we, as consumers, benefit from avoiding this mineral to preserve our long-term health?

A carcinogen is a substance that causes cellular malfunction, causing the cell to become cancerous and therefore potentially lethal to the surrounding tissue and ultimately to the body as these rapidly mutating cells growth take over. With the increase in cancer rates among all segments of the population, many people are trying to reduce or eliminate their exposure to carcinogens. Titanium dioxide is considered an inert and non-toxic substance by many regulatory bodies, such as MSDS (Material Safety Data Sheets) and others charged with the responsibility of safeguarding the health of occupational workers and public health. The MSDS states that titanium dioxide can cause some lung fibrosis at fifty times more than nuisance dust, defined by the US Department of Labor as 15 mg / m cubed (OSHA) or 10 mg / m cubed (ACGIH Threshold Limit Value). The ACGIH states that titanium dioxide “is not classifiable as a human carcinogen.” Symptoms of chronic overexposure to titanium dioxide in an industrial setting, according to the MSDS, include a “slight increase in the incidence of lung tumors in laboratory rats.” It also states that “when titanium dioxide was administered to rats / mice in a carcinogenic bioassay, it was not carcinogenic.” NIOSH states that at 5000 mg / cubic m there was slight pulmonary fibrosis, concluding that this substance was carcinogenic in rats.

The NIOSH statement of carcinogenicity in rats is based on a study by Lee, Trochimowicz & Reinhardt, “Pulmonary Response of Rats Exposed to Titanium Dioxide by Inhalation for Two Years” (1985). The authors of this study found that rats chronically exposed to excessive dust loading of 250 mg / m in buckets and impaired cleaning mechanisms within the rat, for six hours a day, five days a week for two years, developed mild lung tumors. They also noted that the biological relevance of these data to human lung tumors is negligible. It is important to note that rats are known to be an extremely sensitive species for developing lung tumors when overloaded with poorly soluble and low toxicity dust particles. The lungs of rats process particles very differently compared to larger mammals, such as dogs, primates, or humans (Warheit, 2004). This sensitivity in the lungs has not been observed in other rodent species such as mice or hamsters (Warheit, 2004), so using the rat model to determine the carcinogenicity of titanium dioxide in humans can be misleading, since extrapolation from species-specific data to humans is wrong.

Many organizations and companies have perpetuated this assessment of the carcinogenicity of titanium dioxide (ewg.org). However, several studies and study reviews have been used to compile the safety disclaimers for the regulations on the permitted use of titanium dioxide. One such study took place in Rome in 1969 between the World Health Organization and the Food and Agriculture Organization of the United Nations. Cross-species analyzes were performed and reviewed to determine the potential toxicity of titanium dioxide. The conference concluded that among the following species: rats, dogs, guinea pigs, rabbits, cats and human males, the ingestion of titanium dioxide in different percentages of the diet and for long periods of time did not cause the absorption of this mineral. Titanium dioxide particles were not detected in the blood, liver, kidney or urine and no adverse effects were observed from ingestion. The United States Food and Drug Administration (2002) allows its ingestion, external application, including the eye area, and considers it a safe substance for public health. Other epidemiological studies showed that workers exposed to titanium dioxide did not show a statistically significant relationship between such exposure to lung cancer and respiratory disease, although some cases of pulmonary fibrosis did occur. These studies were conducted in industrial settings where increased exposure puts these people at greater risk than the average person.

Titanium dioxide is listed as a safe pigment with no known adverse effects. It is not listed as a carcinogen, mutagen, teratogen, comedogen, toxin, or trigger for contact dermatitis in any other safety regulatory publication besides NIOSH (Antczak, 2001; Laboratory of Physical and Theoretical Chemistry, University of Oxford, respectively). It is reasonable to conclude then that titanium dioxide is not a carcinogenic substance and is generally safe for use in food, medicine, paint, and cosmetics. However, this does not end the debate, as there is still controversy over the safety of a unique form of titanium dioxide.

One form of mineral or mineral extract, including titanium dioxide, that we should be concerned about is ultrafine particles or nanoparticles. As technology has advanced, so has its ability to take normal-sized mineral particles and reduce them to sizes never before imagined. While many praise this new technology, others warn of its inherent dangers to our bodies. A study by Churg et. Alabama. at the University of British Columbia in their paper “Induction of fibrogenic mediators by fine and ultrafine titanium dioxide in rat tracheal explants” (1999) found that ultrafine particles of the anatase form of titanium dioxide, which are less than 0.1 microns , are pathogenic or cause of disease (see Table 1).

Table 1: Mineral pigment particle measurements

Particle size | Measurement
Thick | Less than 10 microns
Good | Less than 2.5 microns
Ultrafine (nanoparticles) | Less than 0.1 microns or 100 nanometers

-etcgroup.org

Table 2: Particle size and entry into the human body

-etcgroup.org

Kumazawa and. Alabama. In his study, “Effects of Titanium Ions and Particles on Neutrophil Morphology and Function” concluded that cytotoxicity (danger to the cell) depended on the particle size of titanium dioxide. The smaller the particle size, the more toxic it is (see Table 2). This conclusion is relevant to the consumer due to the increasing use of micronized pigments in sunscreens and color cosmetics in the cosmetic industry. Titanium dioxide nanoparticles are used in sunscreens because they are colorless at that size and still absorb ultraviolet light. Many cosmetic companies are profiting from metal oxide nanoparticles. However, we have seen that if the titanium dioxide particles used to act as a sunscreen are small enough, they can penetrate cells, leading to photocatalysis inside the cell and damaging DNA after exposure. in sunlight (Powell, et. al. 1996). The fear is that this could lead to skin cancer. Studies with subjects who applied micronized titanium dioxide sunscreens daily for 2-4 weeks showed that the skin can absorb microfine particles. These particles were observed in the percutaneous layers of the skin under ultraviolet light. Coarse or fine titanium dioxide particles are safe and effective in deflecting and absorbing ultraviolet light, protecting the skin, but consumers should avoid using products with micronized mineral pigments, whether in sunscreen or color cosmetics.

As with any health problem, relevant studies need to be closely examined to reach balanced conclusions about their impact on our health and well-being. Risk determinations are often made without considering actual hazards and real-life exposures (Warheit, 2004). Coarse or fine particle size titanium dioxide and other mineral pigments are considered safe by Organic Make-up Co. based on available studies and information discussed in this article. Despite repeated requests for micronized pigments in our color cosmetics, we insist on using only coarse or fine mineral pigment particles, balancing our need to look beautiful with our most urgent need to stay healthy. With the multitude of cosmetics and chemicals available to us, it is in our best interest to educate ourselves as consumers and make pure, natural, and simple decisions to protect our health and longevity.

References:

– Antczak, Cosmetics Unmasked. Harper Collins; London: 2001

– Blake, et.al. “Application of the photocatalytic chemistry of TiO2 to the disinfection and destruction of cancer cells”, separation and purification methods; Vol 28 (1) 1999 p.1-50

– Churg, Gilks, Dai, UBC Dept. of Pathology. Am J Physiol Lung Cell Mol Physiol. Vol 277 Issue 5 L975-L982, 1999

– Dunford, et. Alabama. FEBS Letters 418, 87 1997

– Etcgroup.org

– Kamazawa, et.al. “Effects of titanium ions and particles on neutrophil morphology and function”. Biomaterials, Sep 23, 2002 (17): 3757-64

– Powell, et. Alabama. GUT 38, 390 1996

– Warheit, David “Nanoparticles: Health Impacts?”. Materials today, Feb. 2004

– Witt, Stephen. Director of Technology Support, N. American Refractories Co.

– http://www.organicmakeup.ca

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Titanium dioxide: toxic or safe?

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