Toxicity dose descriptors from animal inhalation studies of 13 nanomaterials and their bulk and ionic counterparts and variation with primary particle characteristics

Abstract

This study collects toxicity data from animal inhalation studies of some nanomaterials and their bulk and ionic counterparts. To allow potential grouping and interpretations, we retrieved the primary physicochemical and exposure data to the extent possible for each of the materials. Reviewed materials are compounds (mainly elements, oxides and salts) of carbon (carbon black, carbon nanotubes, and graphene), silver, cerium, cobalt, copper, iron, nickel, silicium (amorphous silica and quartz), titanium (titanium dioxide), and zinc (chemical symbols: Ag, C, Ce, Co, Cu, Fe, Ni, Si, Ti, TiO₂, and Zn). Collected endpoints are: a) pulmonary inflammation, measured as neutrophils in bronchoalveolar lavage (BAL) fluid at 0-24 hours after last exposure; and b) genotoxicity/carcinogenicity. We present the dose descriptors no-observed-adverse-effect concentrations (NOAECs) and lowest-observed-adverse-effect concentrations (LOAECs) for 88 nanomaterial investigations in data-library and graph formats. We also calculate ‘the value where 25% of exposed animals develop tumors’ (T25) for carcinogenicity studies. We describe how the data may be used for hazard assessment of the materials using carbon black as an example. The collected data also enable hazard comparison between different materials. An important observation for poorly soluble particles is that the NOAEC for neutrophil numbers in general lies around 1 to 2 mg/m³. We further discuss why some materials’ dose descriptors deviate from this level, likely reflecting the effects of the ionic form and effects of the fiber-shape. Finally, we discuss that long-term studies, in general, provide the lowest dose descriptors, and dose descriptors are positively correlated with particle size for near-spherical materials.

Keywords:

• Nanoparticle
• risk assessment
• toxicology
• specific surface area
• TiO₂

Disclosure statement

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

Supplemental materials

The data library of the nanomaterials is included as a Supplemental Materials Excel file. The data library will also be made available in the NanoSafer tool (NFA 2022). A Supplemental Materials Word File 2 includes supplemental tables and graphs.

Data availability statement

The data that support the findings of this study are openly available are available in the Supplemental materials and on the Nanosafer website at www.nanosafer.org

Additional information

Funding

This work was supported by caLIBRAte project funded by the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No 686239; and Gov4Nano, funded by the Horizon 2020 Research and Innovation Programme under Grant Agreement 814401.