Substitute Fibre Safety Evaluation and WHO Criteria
topic
WHO fibre biopersistence evaluation protocol measures the half-time for fibre clearance from rat lung following short-term inhalation exposure, with fibres showing half-life below 10 days for long fibres above 20 micrometres considered biologically cleared and exonerated from carcinogenicity classification; in vitro dissolution rate testing in simulated lung fluid at pH 4.5 and 7.4 provides a screening tool correlated with in vivo biopersistence measurements.
Role
Provides the regulatory toxicology framework within which mineral wool, ceramic fibre, and novel synthetic mineral fibre manufacturers demonstrate product safety by showing rapid fibre dissolution and clearance from lung tissue, enabling EU Note Q regulatory exoneration from carcinogen classification and satisfying the precautionary biopersistence criteria that replaced the failed single-fibre-geometry-based cancer risk model.