T Oyabu et al. J Occup Health (2006) Vol.48 p 44-48
“The Effect of Lung Burden on Biopersistence and Pulmonary Effects in Rats Exposed to Potassium Octatitanate Whiskers (POW) by Intratracheal Instillation.”
Potassium Octatitanate whiskers (K2Ti8O17) (POW) are typically of 5 μm in length and are classified as refractory ceramic fibres (aka Fybex). They are used as an asbestos substitute.