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Contributors JAT drafted the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests The author provides consultancy services to a range of customers including the Titanium Dioxide Manufacturers Association and other chemical industry groups. However, the opinions expressed in the letter are entirely those of the author.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; internally peer reviewed.
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