Toxicological evaluation of polycrystalline wools in human lung cells

Abstract

Aim: Polycrystalline wools (PCW) are included with Refractory ceramic fibers (RCF) in the alumino-silicates family of High Temperature Insulation Wools (HTIW). IARC includes PCW in the ceramic fibers group and considers them as possible human carcinogens (GROUP 2B). Since PCW toxicity is not yet clear, our aim was to evaluate their toxic and inflammatory effects and to compare them with the known RCF effects.

Method: We exposed human bronchial (BEAS-2B) and alveolar (A549) cells to 2–100 µg/mL (2.4 × 10³–1.2 × 10⁵ fibers/mL; 2.51 × 10³–1.26 × 10⁵ fibers/cm² of PCW and 7.4 × 10³–3.7 × 10⁵ fibers/mL; 7.75 × 10³–3.87 × 10⁵ fibers/cm² of RCF) of the tested fibers to evaluate potential viability reduction, apoptosis, membrane damage, direct/oxidative DNA-damage, cytokine release.

Results: In A549, PCW did not induce cytotoxicity and apoptosis but they induced significant dose-dependent DNA-damage, although lower than RCF; only RCF induced oxidative effects. PCW also induced an increase in IL-6 release at 100 µg/mL (1.2 × 10⁵ fibers/mL; 1.26 × 10⁵ fibers/cm²). In BEAS-2B, PCW did not induce cell-viability reduction RCF induced a dose-dependent cell-viability decrease. Both fibers show a dose-dependent increase of apoptosis. In BEAS-2B, PCW also induced dose-dependent DNA-damage, although lower than RCF, and slight oxidative effects similar to RCF. PCW also induced an increase of IL-6 release; RCF induced a decrease of IL-8. Summarizing, PCW induce direct-oxidative DNA-damage although to a lower extent than RCF observed by both mass-based and fiber number-based analysis.

Conclusion: For the first time, the study shows the potential toxicity of PCW, usually considered safe, and suggests to perform further in vitro studies, also on other cell types, to confirm these findings.

Keywords:

• Polycrystalline wools (PCW)
• refractory ceramic fibers (RCF)
• toxicity
• DNA damage
• fpg-comet assay
• cytokine release

Author contributions

Conceptualization, D.C. and C.L.U.; formal analysis, D.C.; investigation, Au.C., A.M.F. An.C. and R.M.; writing—original draft preparation, Au.C, D.C. and C.L.U.; writing—review and editing, Au.C, D.C., A.M.F. and C.L.U.; visualization, Au.C; supervision, D.C. and S.I. All authors read and approved the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

All relevant data are included in the manuscript. They are also available from the authors on reasonable request.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.