Titanium dioxide (TiO2) is one of the most critical pigments in our daily life.  It is crucial in everyday items such as toothpaste, sunscreen, chewing gums and paints. When it is used as a pigment, it is a critical ingredient in white inks and coatings; for example, a layer of white ink can help colors pop on packaging.
 
TiO2 has been in the news for most of 2017, beginning with higher prices. There has been significant consolidation in China’s TiO2 segment, leading to higher prices, and China has also reportedly restricted production due to air quality concerns. A January 2017 fire at Huntsman’s TiO2 plant in Pori, Finland, further restricted capacity for TiO2 for graphic arts.                   
 
This has led ink manufacturers to announce price increases on inks using titanium dioxide; for example, Siegwerk issued a statement in early March announcing higher prices for all inks that have titanium dioxide.
 
All of this is challenging enough, but environmental issues have now come up that could take TiO2 to another, more difficult, level. TiO2 is a key ingredient in sunscreens, and there have been concerns in Europe over the use of nanoparticles in sunscreen, toothpaste and much more. The concern, in particular, is over nanoparticles of TiO2. This led the European Chemicals Agency (ECHA) to determine that titanium dioxide could be a carcinogen if it is inhaled.
 
There have been limited studies on the toxicity of titanium dioxide. Laboratory studies on rodents have found that high levels of titanium dioxide nanoparticles caused respiratory tract cancers. This led ECHA to post:
 
“ECHA’s Committee for Risk Assessment (RAC) concluded that the available scientific evidence meets the criteria in the CLP Regulation to classify titanium dioxide as a substance suspected of causing cancer through the inhalation route. The opinion will be formally adopted later by written procedure or at the September meeting.
 
“The committee assessed the carcinogenic potential of titanium dioxide against the criteria in the Classification, Labelling and Packaging (CLP) Regulation and, having considered the available scientific data, concluded that it meets the criteria to be classified as suspected of causing cancer (category 2, through the inhalation route).
 
“The committee also concluded that there was insufficient evidence to classify titanium dioxide in the more severe category for carcinogenicity (category 1B) as was originally proposed by the dossier submitter, France. This more severe category refers to a substance which is presumed to cause cancer.
 
“Following adoption, the opinion will go through a normal editorial check before it is sent to the European Commission for final decision making. The opinion will also be made available on ECHA’s website at the same time.”
 
In the CLH Report for Titanium Dioxide, dated May 2016, the following is stated:
 
            “As further detailed in the dossier, TiO2 is considered poorly soluble particles and the main proposed mechanism of  carcinogenicity  by  inhalation  is  thus  based  on  the  low  solubility  and  biopersistency of  the  particles  leading  to  pulmonary  inflammation  then  oxidative  stress.  Secondary genotoxicity and cell proliferation result in carcinogenicity. Nevertheless, possible direct genotoxicity cannot be excluded.” (https://echa.europa.eu/documents/10162/594bf0e6-8789-4499-b9ba-59752f4eafab)
 
Not surprisingly, the Titanium Dioxide Manufacturers’ Association (TDMA) does not agree. ON its website (http://www.tdma.info/tio2-and-safety), the association writes:
 
“A link between TiO2 and cancer has never been established. The effect in rats relied upon by the French proposal are not reproducible in other species such as mice or hamsters. Most importantly, extensive studies conducted by both industry and independent institutions have found no evidence of effects in humans. While a small number of studies have associated TiO2 with cancer, these studies are based on exposing rats to quantities of TiO2 far above what humans, even workers, would ever be exposed to.”
 
I am not going to speak to the safety of titanium dioxide; I don’t have the expertise. One of the strange and troubling aspects in the European regulatory environment is the patchwork nature of regulations. For example, one country can make its own statements, in this case France. (Actually, this happens in the separate US states as well, as shown by the California Prop. 65).
 
One question I have not seen discussed is that ink and paints are, in essence, liquids. I would guess that the concern would be processing the liquids, and not for the end user. TDMA reports that four studies have been conducted among a reported 24,000 workers at TiO2 plants, and there has been “no association with increased risk of cancer or with any other adverse effects from exposure to TiO₂”
 
Ink manufacturers are continually reviewing and evaluating new toxicity information regarding materials used in their products. The outcome of the debate over the toxicity of TiO2 notwithstanding, TiO2 formulated into an ink or coating does not present an inhalation exposure hazard to our customers.   Proper industrial hygiene practices require minimization of all chemical exposure hazards that can occur during the manufacturing process as well as ongoing review of the toxicity of the raw material stream.  
 
Ultimately, the European Commission, the lead authority in the EU, will likely decide the fate of TiO2. For ink manufacturers, this could have some huge impacts on materials for formulating.