Editing Titanium dioxide (section)

===Inhalation===
Titanium dioxide dust, when inhaled, has been classified by the [[International Agency for Research on Cancer]] (IARC) as an [[list of IARC Group 2B carcinogens|IARC Group 2B carcinogen]], meaning it is ''possibly carcinogenic to humans''.<ref name=IARC>{{cite book|publisher= International Agency for Research on Cancer|year= 2006 |volume= 93|title=Titanium dioxide|url= http://monographs.iarc.fr/ENG/Monographs/vol93/mono93.pdf}}</ref><ref>{{cite web |url=https://www.ccohs.ca/headlines/text186.html|title=Titanium Dioxide Classified as Possibly Carcinogenic to Humans |date= August 2006|website=Canadian Centre for Occupational Health & Safety}}</ref> The US [[National Institute for Occupational Safety and Health]] recommends two separate exposure limits. NIOSH recommends that fine {{chem|Ti|O|2}} particles be set at an exposure limit of 2.4&nbsp;mg/m<sup>3</sup>, while [[ultrafine particle|ultrafine]] {{chem|Ti|O|2}} be set at an exposure limit of 0.3&nbsp;mg/m<sup>3</sup>, as time-weighted average concentrations up to 10 hours a day for a 40-hour work week.<ref>{{cite web |author= National Institute for Occupational Safety and Health |title= Current Intelligence Bulletin 63: Occupational Exposure to Titanium Dioxide (NIOSH Publication No. 2011-160) |publisher= National Institute for Occupational Safety and Health |url= https://www.cdc.gov/niosh/docs/2011-160/pdfs/2011-160.pdf}}</ref>

Although no evidence points to acute toxicity, recurring concerns have been expressed about nanophase forms of these materials. Studies of workers with high exposure to TiO<sub>2</sub> particles indicate that even at high exposure there is no adverse effect to human health.<ref name="auto"/>