Titanium dioxide (TiO2) is an inorganic compound that can be found in paints and varnishes, toothpaste, chewing gum and sun creams, for example. However, its use is controversial, as harmful effects on human health cannot be ruled out based on the available evidence. The European Commission has therefore classified titanium dioxide as possibly carcinogenic, especially if it is ingested in powder form via the air and the respiratory tract is exposed to TiO2.
There is a particularly high risk of inhaling TiO2, especially in factories that produce TiO2 powder. In recent decades, however, only a few studies have been conducted in TiO2 processing plants in which workers were recruited and the health consequences of inhaling TiO2 were investigated. People in these plants are potentially exposed to much higher doses of TiO2 than the general population.
The aim of a new analysis, with the participation of the Chair of Epidemiology of Prof. Dr. Stefanie Klug, together with the University Medical Center Mainz, was therefore to provide an overview of epidemiological studies on work-related health risks associated with titanium dioxide and their methodological aspects. The results were published under the title "Health risks of titanium dioxide (TiO2) dust exposure in occupational settings - A scoping review" in the "International Journal of Hygiene an Environmental Health". The journal has an impact factor of 7.401.
"The idea for this review is based on a large study by the International Agency for Research on Cancer (IARC), in which we investigated whether there is an association between titanium dioxide and lung cancer among factory workers in various European countries," explains Prof. Klug. "First author Jannis Hansa is working on this topic as part of his master's thesis in the field of epidemiology at the University Medical Center Mainz, which is why he has now prepared this scoping review."
In the IARC study, the link between inhalation of TiO2 and lung cancer in humans was not clear, but there were indications in animal experiments that TiO2 powder can cause cancer. The recently published review took a closer look at ten studies from 1988 to 2022 that looked at all-cause mortality and lung cancer mortality.
With regard to all-cause mortality, most of the cohort studies analyzed found no association with TiO2 exposure. However, in a European study from 2004 with over 15,000 workers in eleven TiO2 factories, a significantly increased risk of lung cancer mortality was found. In addition, a US cohort study from 2013 with over 3,600 participants from three factories found an increased mortality risk, particularly with regard to lung cancer, using company employees who were not exposed to TiO2 as a reference. However, in many of these studies, the analysis of confounding factors, in particular smoking, was inadequate, which naturally limits the significance of the results.
Accordingly, the review concludes that the relationship between occupational TiO2 exposure and mortality is unclear, as many do not provide significant evidence of a carcinogenic risk from inhaled TiO2 dust. However, recent scientific discussion has raised the question of possible methodological flaws in the studies conducted, which have led to biased results. Due to these new developments and the inconsistencies in earlier analyses, further studies are therefore necessary in order to formulate more valid assessments of the risks of TiO2 dust exposure.
To the homepage of the Chair of Epidemiology
To the publication „Health risks of titanium dioxide (TiO2) dust exposure in occupational settings – A scoping review“ in the „International Journal of Hygiene an Environmental Health”
Contact:
Prof. Dr. Stefanie Klug
Chair of Epidemiology
Department Health and Sport Sciences
TUM School of Medicine and Health
Georg-Brauchle-Ring 56
80992 München
phone: 089 289 24950
e-mail: stefanie.klug(at)tum.de
Text: Romy Schwaiger
Photos: “International Journal of Hygiene and Environmental Health”/Astrid Eckert/TUM