Biodegradability of inhaled p-aramid respirable fiber-shaped particulates (RFP): Mechanisms of RFP shortening and evidence of reversibility of pulmonary lesions

David B. Warheit, K. L. Reed, Kent E Pinkerton, T. R. Webb

Research output: Contribution to journalArticle

4 Scopus citations


These studies elucidated mechanisms of inhaled p-aramid respirable fiber-shaped particulates (RFP) biodegradation in the lungs of exposed rats and hamsters. We postulate that lung fluids coat/activate inhaled p-aramid RFP which deposits in the lung and promote enzymatic attack and consequent shortening. p-Aramid or cellulose (biopersistent control) RFP were instilled into the lungs of rats and the lungs digested 24 h later using two different (KOH or enzymatic) digestion techniques. In vivo, the enzyme but not the KOH solution produced shortening of p-aramid but not cellulose RFP recovered from the lungs. For in vitro studies, the two RFP-types were incubated with BAL fluids and underwent simulated digestions; also rat lung epithelial cells, macrophages or co-cultures were incubated with p-aramid and digested at 1, 24, or 168 h postexposure. The results of in vitro acellular studies demonstrated that only p-aramid RFP incubated in BAL fluids and digested by the enzyme method were shortened. In vitro cellular studies demonstrated a shortening of p-aramid RFP in macrophages and co-cultures but not in lung epithelial cells at 24 h and 1 week postexposure. These results demonstrate that lung fluids coat and catalyze the p-aramid RFP as a prelude for shortening and describe a likely mechanism for the biodegradability of inhaled p-aramid RFP in the lungs of exposed animals.

Original languageEnglish (US)
Pages (from-to)259-267
Number of pages9
JournalToxicology Letters
Issue number1-3
StatePublished - Feb 28 2002



  • Biodegradability
  • Cellulose RFP
  • Fiber toxicology
  • Man-made organic fibers
  • p-Aramid RFP

ASJC Scopus subject areas

  • Toxicology

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