Toxicological inhalation studies in rats to substantiate grouping of zinc oxide nanoforms
Author:
Thoma Tizia1, Ma-Hock Lan2, Schneider Steffen2, Honarvar Naveed2, Treumann Silke2, Groeters Sibylle2, Strauss Volker2, Marxfeld Heike2, Seiffert Svenja3, Wohlleben Wendel3, Dammann Martina2, Wiench Karin4, Lambaert Noömi5, Spirlet Christine5, Vasquez Marie6, Dewhurst Nicole6, Landsiedel Robert2
Affiliation:
1. BASF Services Europe GmbH 2. BASF SE, Experimental Toxicology and Ecology 3. BASF SE, Analytical and Material Science 4. BASF SE, Product Stewardship, Regulatory Toxicology Chemicals 5. International Zinc Association 6. Helix3 Inc.
Abstract
Abstract
Background
Different zinc oxide (ZnO) nanoforms were identified as a probable set of similar nanoforms for a common hazard assessment. To justify this grouping, toxicological studies were performed: A 90-day inhalation study (OECD test guideline no. (TG) 413) combined with a reproduction/developmental (neuro)toxicity screening test (TG 421/424/426) was performed in rats with coated and uncoated ZnO nanoforms in comparison with microscale ZnO particles and soluble zinc sulfate. In addition, genotoxicity in the nasal cavity, lungs, liver, and bone marrow was examined via comet assay (TG 489) after 14-day inhalation exposure.
Results
ZnO nanoparticles caused local toxicity in the respiratory tract. Systemic effects that were not related to the local irritation were not observed. There was no indication of impaired fertility, developmental toxicity, or developmental neurotoxicity. No indication for genotoxicity of any of the test substances was observed. Local effects were similar across the different ZnO test substances and were reversible after the end of the exposure.
Conclusion
With exception of local toxicity, this study could not confirm the occasional findings in some of the previous studies regarding the above-mentioned toxicological endpoints. The two representative ZnO nanoforms and the microscale particles showed similar local effects. The ZnO nanoforms most likely exhibit their effects by zinc ions as no particles could be detected after the end of the exposure, and exposure to rapidly soluble zinc sulfate had similar effects. Obviously, material differences between the ZnO particles do not substantially alter their toxicokinetics and toxicodynamics. The grouping of ZnO nanoforms into a set of similar nanoforms is justified by these observations.
Publisher
Research Square Platform LLC
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