Titanium dioxide

2021-10-01

Titanium dioxide (TiO2) (CAS Number 13463-67-7) is a non-combustible, white, crystalline, solid, odourless powder. It is insoluble in water, hydrochloric acid, nitric acid, and alcohol, and it is soluble in hot concentrated sulphuric acid, hydrogen fluoride, or alkali. TiO2 has several naturally occurring mineral forms, or polymorphs, which have the same chemical formula and different crystalline structure. Common TiO2 polymorphs include rutile (CAS Number 1317-80-322 2) and anatase (CAS Number 1317-70-0). While both rutile and anatase belong to the tetragonal crystal system, rutile has a denser arrangement of atoms. Both anatase and rutile are used as white pigment. Rutile TiO2 is the most commonly used white pigment because of its high refractive index and relatively low absorption of light. Anatase is used for specialised applications (e.g., in paper and fibres). TiO2 does not absorb visible light, but it strongly absorbs ultraviolet (UV) radiation. Commercial rutile TiO2 is prepared with an average particle size of 0.22 μm to 0.25 μm. Pigment-grade TiO2 refers to anatase and rutile pigments with a median particle size that usually ranges from 0.2 μm to 0.3 μm. Particle size is an important determinant of the properties of pigments and other final products. [1]

Uses [1]

TiO2 is used mainly in paints, varnishes, lacquer, paper, plastic, ceramics, rubber, and printing ink. In addition, it is used in welding rod coatings, floor coverings, catalysts, coated fabrics and textiles, cosmetics, food colorants, glassware, pharmaceuticals, roofing granules, rubber tire manufacturing, and in the production of electronic components and dental impressions. Both the anatase and rutile forms of TiO2 are semiconductors. TiO2 white pigment is widely used due to its high refractive index. Since the 1960s, TiO2 has been coated with other materials (e.g., silica, alumina) for commercial applications.

Routes of Exposure [2]

Exposure to titanium dioxide results from breathing in titanium dioxide dust. Possible exposure to intermediate products in titanium dioxide production may also occur. Exposure may occur at any stage in the mining of ores, in the preparation of titanium dioxide, and in any of the industries in which the powder is stored and used. Whilst the most common route of exposure is inhalation, ingestion is possible when some dust accumulates on mucosal surfaces of the oropharynx and nasopharynx.

Health Effects

Acute Toxicity [2]

Titanium dioxide is an irritant to the upper airway, as are other nuisance dusts. No evidence indicates that it induces an acute inflammatory reaction at commonly seen exposure concentrations. In workers with pre-existing chronic obstructive airway disease, titanium dioxide may exacerbate symptoms.

Chronic Toxicity [3]

No conclusions can be drawn from the few studies that show respiratory effects in titanium-dioxide exposed workers, because of concurrent exposure to other substances that are well known to cause lung disease. There was no association between titanium dioxide exposure and increased mortality from any cause in a retrospective cohort mortality study of 4241 titanium dioxide workers. A few human population studies or clinical studies involving titanium-dioxide exposed workers have shown effects such as decreased lung function, mild fibrosis, and thickening of the lining of the chest cavity (pleural thickening). However, the workers in these studies were also exposed to other substances including asbestos and/or silica, which are well known to cause lung disease. Therefore, no conclusions can be drawn. In general, long-term exposures to high concentrations of dust may cause increased mucous flow in the nose and respiratory system. This condition usually disappears after exposure stops. Controversy exists as to the role occupational exposure to dust has in the development of chronic bronchitis (inflammation of the air passages into the lungs). Other factors such as smoking and general air pollution are also important, but dust exposure may contribute to this effect. In animal studies, long-term inhalation exposure has caused persistent adverse effects on the lungs (e.g. inflammation, fibrosis, changes to alveolar cells), which are believed to result from dust overloading of the lungs. Effects with ultrafine titanium dioxide occur at much lower exposure concentrations than are required with the larger sized pigment grade particles. The effects are more closely related to lung burden in terms of the surface area rather than the mass of the particles.

Genetic Effects [2]

No data are available regarding human genetic effects, and very limited epidemiologic data about carcinogenicity are available.

Carcinogenic [3]

The International Agency for Research on Cancer (IARC) has determined that titanium dioxide is possibly carcinogenic to humans (Group 2B) based on inadequate evidence in humans and sufficient evidence in experimental animals. This conclusion relates to long-term inhalation exposure to high concentrations of pigmentary (powdered) or ultrafine titanium dioxide. The available human studies do not suggest an association between occupational exposure to titanium dioxide and risk for cancer.

Safety [4]


  • First Aid Measures

  • Eye Contact: Check for and remove any contact lenses. In case of contact, immediately flush eyes with plenty of water for at least 15 minutes. Get medical attention if irritation occurs.

  • Skin Contact: Wash with soap and water. Cover the irritated skin with an emollient. Get medical attention if irritation develops.
  • Inhalation: If inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention.
  • Ingestion: Do NOT induce vomiting unless directed to do so by medical personnel. Never give anything by mouth to an unconscious person. If large quantities of this material are swallowed, call a physician immediately. Loosen tight clothing such as a collar, tie, belt or waistband.

Exposure Controls & Personal Protective Equipment

Engineering Controls

Use process enclosures, local exhaust ventilation, or other engineering controls to keep airborne levels below recommended exposure limits. If user operations generate dust, fume or mist, use ventilation to keep exposure to airborne contaminants below the exposure limit.

  • Personal Protective Equipment

  • Safety glasses

  • lab coat
  • dust respirator (Be sure to use an approved/certified respirator or equivalent)
  • gloves

Personal Protection in Case of a Large Spill:

  • Splash goggles
  • full suit
  • dust respirator
  • boots
  • gloves
  • A self-contained breathing apparatus should be used to avoid inhalation of the product.
  • Suggested protective clothing might not be sufficient; consult a specialist BEFORE handling this product.

Regulation [5]

United States

OSHA: The Occupational Safety & Health Administration have established the following Permissible Exposure Limit (PEL) for titanium dioxide:

  • General Industry: 15 mg/m3 TWA
  • Maritime: 15 mg/m3 TWA

ACGIH: The American Conference of Governmental Industrial Hygienists has set a Threshold Limit Value (TLV) for titanium dioxide of: 10 mg/m3 TWA; Appendix A4 – Not Classifiable as a Human Carcinogen

NIOSH: The National Institute for Occupational Safety and Health has set the following Recommended Exposure Limit (REL): Appendix A – NIOSH Potential Occupational Carcinogens

Australia

Safe Work Australia: Safe Work Australia has established a Time Weighted Average (TWA) concentration for titanium dioxide of 10mg/m3 for an 8 hour workday.

References

http://www.cdc.gov/niosh/review/public/TIo2/pdfs/TIO2Draft.pdf

http://www.ceramicstoday.com/articles/titanium_dioxide_ENG.htm

http://www.ccohs.ca/oshanswers/chemicals/chem_profiles/titanium_dioxide/health_td.html

http://www.sciencelab.com/msds.php?msdsId=9925268

https://www.osha.gov/dts/chemicalsampling/data/CH_272100.html

http://www.safeworkaustralia.gov.au/sites/swa/about/Publications/Documents/772/Workplace-exposure-standards-for-airborne-contaminants.docx