Biopersistence and In Vitro Dissolution Testing
topic
In vitro biopersistence testing dissolves fibre samples in simulated lung fluid at pH 7.4 for extracellular and pH 4.5 for intracellular phagosomal conditions, measuring dissolved silicon and other elements by ICP-OES at intervals over 5 to 20 days and calculating dissolution rate as nanograms per square centimetre per hour; dissolution rate above 100 nanograms per square centimetre per hour at pH 7.4 correlates with in vivo biopersistence below the WHO 10-day half-time criterion.
Role
Provides the regulatory toxicology screening test for carcinogenicity classification of mineral fibres under EU Directive 97/69/EC Note Q exemption criteria, enabling ceramic fibre and special purpose fibre manufacturers to demonstrate rapid fibre dissolution that confers low biopersistence and satisfies the exemption criteria avoiding carcinogen labelling obligations for fibres meeting dissolution rate thresholds.