Biopersistence

Biopersistence is the capacity of a foreign substance to remain in an organism after exposure, resisting dissolution, metabolism, and clearance. In toxicology and pharmacology, biopersistence describes how long a chemical, particle, or fiber persists in tissues and fluids, influencing potential for chronic effects.

Biopersistence is especially relevant for inhaled or ingested materials. Substances that are highly biopersistent tend to accumulate in the lungs, lymph nodes, liver, and spleen, sustaining inflammation or toxic responses over time, while those that are rapidly dissolved or excreted have shorter residence times.

Factors shaping biopersistence include chemical composition, solubility in biological fluids, surface properties, size and shape, aggregation state, and the formation of a protein corona. Dissolution rate, biodegradation, and resistance to enzymatic metabolism determine residence time; clearance often proceeds via macrophage phagocytosis, lymphatic drainage, hepatic processing, and renal elimination.

Assessment methods combine in vitro dissolution tests, animal and human pharmacokinetic studies, and measurements of tissue burden and half-life. Regulatory assessments may use biopersistence as an indicator of potential for long-term hazard, complementing solubility, reactivity, and exposure level data.

Examples illustrate the concept: asbestos fibers are highly biopersistent in lung tissue, contributing to chronic disease, whereas soluble salts show low biopersistence due to rapid dissolution and clearance. Nanomaterials exhibit variable biopersistence dependent on composition, size, and surface treatment.