Titanium dioxide is the subject of a new controversy, yet it is a substance as old as the earth itself. It is one of the top fifty chemicals produced worldwide. It is a naturally occurring, opaque white mineral found in two main forms: rutile and anatase. Both forms contain pure titanium dioxide that binds 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. Concern has been raised by studies that have pointed to titanium dioxide as a carcinogen and photocatalyst, thus creating fear among consumers. But are these claims true? What does the investigation confirm about these accusations? Would we as consumers benefit from avoiding this mineral to preserve our long-term health?
A carcinogen is a substance that causes a cell to malfunction, causing the cell to become cancerous and therefore potentially lethal to surrounding tissue and ultimately to the body as these rapidly mutated cells growth take control. With rising 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 the nuisance dust, defined by the US Department of Labor as 15 mg/cubic m3 (OSHA) or 10 mg/cubic m3 (Threshold Limit Value of the ACGIH). 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 “slightly increased incidence of lung tumors in laboratory rats.” It also states that “when titanium dioxide was fed to rats/mice in a carcinogenic bioassay, it was not carcinogenic.” The NIOSH declares that at 5000 mg/m³ there was a slight pulmonary fibrosis, concluding that this substance was carcinogenic in rats.
The NIOSH rat carcinogenicity statement is based on a study by Lee, Trochimowicz and Reinhardt, “Lung Response of Rats Exposed to Inhalation Titanium Dioxide for Two Years” (1985). The authors of this study found that rats chronically exposed to an excessive dust load of 250 mg/m3 and impaired elimination 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 to develop lung tumors when overloaded with poorly soluble, low toxicity dust particles. Rat lungs 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), therefore using the rat model to determine the carcinogenicity of titanium dioxide in humans may be misleading, since the extrapolation of species-specific data to humans is flawed
Many organizations and companies have perpetuated this evaluation of the carcinogenicity of titanium dioxide (ewg.org). However, several studies and reviews of studies have been used to compile the safety disclaimers for the regulations on the permitted use of titanium dioxide. A review of this type of 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, ingestion of titanium dioxide in variable percentages of the diet and for long periods of time did not result in the absorption of this mineral. Titanium dioxide particles were not detected in the blood, liver, kidneys, or urine, and no adverse effects from ingestion were observed. The US Food & 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 have a statistically significant relationship between titanium dioxide exposure and lung cancer and respiratory diseases, although some cases of pulmonary fibrosis did occur. These studies were conducted in industrial settings where the 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 contact dermatitis trigger in any other safety regulatory publication other than NIOSH (Antczak, 2001; Physical and Theoretical Chemical Laboratory, University of Oxford, respectively). So it is reasonable to conclude 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 or nano particles. 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 the dangers inherent in our bodies. A study by Churg et. para. at the University of British Columbia in their article “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 disease-causing (see Table 1).
Table 1: Measurements of mineral pigment particles
Particle size | Measurement
thick | Less than 10 microns
Slim | 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
Nanoparticle size | Entry point
70 nanometers | alveolar surface of the lung
50 nanometers | cells
30 nanometers | Central Nervous System
Less than 20 nanometers | no data yet
-etcgroup.org
Kumazawa et al. para. in his study, “Effects of Titanium Ions and Particles on Neutrophil Morphology and Function,” he concluded that cytotoxicity (danger to the cell) depended on the size of the titanium dioxide particles. 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 the cosmetic industry in sunscreens and color cosmetics. Titanium dioxide nanoparticles are used in sunscreens because they are colorless at that size and still absorb ultraviolet light. Many cosmetic companies are capitalizing on metal oxide nanoparticles. We have seen, however, that if the titanium dioxide particles used to act as a sunscreen are small enough, they can penetrate cells, leading to photocatalysis within the cell, causing DNA damage after exposure. exposure to sunlight (Powell, et. al. 1996) The fear is that this could lead to skin cancer. Studies with subjects applying micronized titanium dioxide sunscreens daily for 2 to 4 weeks demonstrated that the skin can absorb microfine particles. These particles were observed in the percutaneous layers of the skin under ultraviolet light. Coarse or fine particles of titanium dioxide are safe and effective in deflecting and absorbing UV light and protecting skin, but consumers should avoid using products with micronized mineral pigments, whether in sunscreens or color cosmetics.
As with any health problem, relevant studies need to be closely examined in order to reach balanced conclusions about their impact on our health and well-being. Often risk determinations are made without considering actual hazards and real life exposures (Warheit, 2004). Titanium dioxide and other coarse or fine particle size mineral pigments are considered safe by The Organic Makeup Co. based on available studies and the information discussed in this article. Despite repeated calls for micronized pigments in our color cosmetics, we insist on using only coarse or fine particles of mineral pigments, balancing our need to look beautiful with our more pressing 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 choices to protect our health and longevity.
References:
– Antczak, Unmasked Cosmetics. HarperCollins; London: 2001
-Blake, et al. “Application of TiO2 Photocatalytic Chemistry to the Disinfection and Elimination of Cancer Cells”, Separation and Purification Methods; Vol 28 (1) 1999 p.1-50
– Churg, Gilks, Dai, UBC Dept. of Pathology. I am J Physiol Lung Cell Mol Physiol. Flight 277 Issue 5 L975-L982, 1999
-Dunford, et. para. FEBS Letters 418, 87 1997
-etcgroup.org
-Kamazawa, et al. “Effects of titanium ions and particles on neutrophil morphology and function”. Biomaterials 2002 Sep 23(17):3757-64
-Powell, et al. para. gut 38, 390 1996
– Warheit, David “Nanoparticles: Health Impacts?”. Materials Today, February 2, 2004
Witt, Stephen. Director of Technology Support, N. American Refractories Co.
– http://www.organicmakeup.ca