Titanium Dioxide

Full Profile

General Information

Titanium dioxide is a mineral substance that occurs naturally in the environment via the oxidation of titanium. It is found as white crystals or as a powder.^[2] It may also be referred to as TiO₂, titanium white (when used as a pigment), or titania.^[2]

Titanium dioxide has been classified by IARC as a Group 2B carcinogen, possibly carcinogenic to humans. Inhalation exposure in rats caused an increased incidence of lung cancer.^[3] Although there were three epidemiological studies available to the IARC working group, all had methodological limitations and none found a significant association between occupational exposure and increased risk of cancer.^[3]

Additionally, titanium dioxide may cause reduced lung function in exposed workers, as well as pleural thickening and mild fibrotic changes.^[3] Other health effects include irritation of the eyes, skin and respiratory tract as well as contact dermatitis, and allergic sensitization.^[2]

Titanium dioxide was initially ranked by CAREX Canada as a Group B (possible high priority) for occupational settings and as a Group C (further investigation needed) for environmental settings. Prioritization was based on the carcinogenicity and other toxic properties of the substance, the prevalence of exposure in Canada, and the feasibility of assessing exposure.

Titanium dioxide has recently identified as an emerging carcinogen research priority due to its use in nanoparticle size ranges.^[4]

Regulations and Guidelines

Occupational Exposure Limits (OEL)

Canadian Jurisdictions	OEL (mg/m3)
Canada Labour Code	10
BC	10 [total dust] 3 [r]
SK, YT	10 20 [stel]
AB, MB, ON, QC, NL, PE, NB, NS	10
NT, NU	5 [r] 10 [total mass]
Other Jurisdictions	OEL (mg/m3)
ACGIH 2011 TLV	10

Canadian Environmental Guidelines

Jurisdiction	Limit	Year
Food Additives Permitted For Use	C – Colouring Agents	2006[5]

Canadian Agencies/Organizations

Agency	Designation/Position	Year
Health Canada	DSL – moderate priority substance with the greatest potential for exposure	2006[9]

Main Uses

Titanium dioxide is used primarily as a white pigment in paints, vinyl compounds, enamels, plastics, specialty papers, inks, foods, toothpastes and cosmetics and skin care products.^[3,12] It is the most commonly used pigment worldwide, accounting for 70% of global volume of pigments produced.^[12] For optimum pigment properties, the particle size is controlled within 0.2 to 0.4 micrometers.^[13]

Titanium dioxide is also used in sunscreens to protect skin from ultraviolet radiation, often in nanoparticle size ranges, since small size increases scattering of UV radiation.^[3]

Nanoparticles

Titanium dioxide tends to be used in its ultrafine size range, nanoparticles, which measure fewer than 100 nanometers. Nanomaterials have unique properties electronically, optically, mechanically, and chemically, which make them useful in a variety of industrial applications. In general, however, the health and environmental effects of these particles is not well understood.^[14]

The toxicity of nanomaterials often differs from the same compound in a larger size fraction. Indeed, the two distinct crystalline TiO₂forms differ in toxicity (anatase is 100 times more cytotoxic than rutile).^[14]

Ultrafine TiO₂ has different shapes, sizes and crystalline structures depending on the application.^[14] The nanoparticles of TiO₂ can exist in shapes such as spheres, rods, wires and agglomerates, and they can be coated with other chemicals, such as alumina.^[14]

Canadian Production & Trade

Titanium dioxide in Canada is produced from ilmenite, rutile, or titanium slag.^[16]

QIT-Fer et Titane operates an ilmenite mine (called Tio) located near Havre-Saint-Pierre, Quebec.^[17] QIT also operates a metallurgical complex to process the ore into titanium slag in nearby Tracy, Quebec.^[17]

Production and Trade

Activity	Quantity	Year
Canadian Production	80,000 t	2005 (forecasted)[15]
Domestic Consumption	114,000 t t	2005 (forecasted)[15]
Export: Mainly to the US	90,156 t of ‘titanium pigments and preps, >80% titanium oxide’	2010[18]
Export: Mainly to the US	1,285 t of ‘titanium oxides’
Import: Mainly from US and Mexico	67,279 t of ‘titanium pigments and preps, >80% titanium oxide’	2010[18]
Import: Mainly from Korea, China	4,147 t of ‘titanium oxides’

Occupational Exposures

Dermal absorption and inhalation are the most important routes of occupational exposure to titanium dioxide.^[2]

The main occupations exposed include workers at titanium mines, titanium dioxide production (particularly milling and packaging), as well as site cleaning and maintenance.^[3] Titanium dioxide exposure via inhalation is only of concern, however, when found in powder or dust form which can be aerosolized. If bound in another product, exposures are expected to be low.^[3]

Environmental Exposures

Titanium oxide is the most common form of titanium, which is the ninth most abundant element in the earth's crust.^[19]

The main source of environmental exposure to titanium dioxide is dermal absorption from sunscreens, cosmetics, paints, and enamels; ingestion is also a potential source via these same products.^[3] Although most Canadians will be exposed to TiO₂ via sunscreen, dermal absorption is not expected to carry the same risk as inhalation exposures.^[2] Populations living in close proximity to titanium mines and industrial plants may be at higher risk of exposure.

Titanium dioxide is not reportable to the NPRI in Canada.^[20]

A search of a consumer product database yielded the following results on current potential for exposure to titanium dioxide in Canada:

US Household Products Database

US Household Products 2010[21]
Results: >200 products
Search Term	Quantity	Product Type
'titanium dioxide’	>200	Paint, make-up, caulking, sunscreens, toothpastes

Sources

1. Wikimedia Commons (2007) Titanium Dioxide
2. US National Library of Medicine (2011) Hazardous Substances Data Bank entry for Titanium Oxide (search term: ‘titanium dioxide’)
3. IARC (2010) Monograph Summary, Titanium dioxide, Volume 93
4. Ward EW et al (2010) Research Recommendations for Selected IARC-Classified Agents. Environ. Health Perspect. 118(10) :1355-1362
5. Health Canada (2006) Food Additives Permitted for Use in Canada
6. Health Canada (2010) Guidelines for Canadian Drinking Water (PDF)
7. Health Canada (1987) Exposure Guidelines for Residential Indoor Air Quality (PDF)
8. Health Canada (2010) Cosmetic Ingredient Hotlist
9. Health Canada (2006) Categorization of the Domestic Substances List under CEPA
10. Environment Canada (2010) Toxic Substances List – CEPA Schedule 1
11. Government of Canada (2008) Chemicals Management Plan – List of all Challenge Substances
12. Canadian Centre for Occupational Health and Safety (2006) Headlines: Titanium Dioxide Classified as Possibly Carcinogenic to Humans
13. US Geological Survey (2009) Minerals Information – Titanium, Statistics and Information
14. Madl AK & Pinkerton KE. (2009) Health effects of inhaled and incidental nanoparticles. Critical Reviews in Toxicology, 39(8): 629-658
15. Camford Information Services (2003) CPI Product Profiles: Titanium Dioxide
16. ICIS (2011) Chemical Intelligence, Titanium Dioxide
17. QIT Fer et Titane (Rio Tinto) (2005)
18. TradeMap (2010) Canadian International Trade (free subscription required)
19. WHO (1982) Environmental Health Criteria 24 - Titanium
20. Environment Canada (2009) The National Pollutant Release Inventory
21. US Department of Health and Human Services (2011) Household Products Database