Quantitative material releases from products and articles containing manufactured nanomaterials: Towards a release library

Environmental and human risk assessment models are critical for estimating the impact of nanomaterials on the ecosystem and human health. Realistic exposure estimates usually require quantitative process-specific release and emission characteristics in specific exposure situation. For nanomaterial-based products, release data suitable for modeling are currently very scarce. Consequently, in this study, we reviewed the release assessment literature and extracted or derived quantitative releases, as well as properties of released fragments from 374 different scenarios on nanomaterial-based products and articles, including artificial weathering, mechanical treatment, spraying, washing and leaching. The release literature has assessed textiles, thermosets, thermoplastics, coated surfaces, sprays, incineration, and other articles and the results are provided for different release processes. Artificial weathering of composites at a UV-dose of ca. 150MJm^‑2 released 10¹ to 10⁵mg·m^‑2 fragments containing nanomaterials and ca. 10^‑4 to 10³mg·m^‑2 nanomaterials. Mechanical treatment released from ca. 9×10⁴ to 3.1×10¹⁰particles·s^‑1. Components treated mechanically after artificial weathering released up to ca. 2.7×10⁶particles·s^‑1. Pump sprays and propellant sprays on average emitted 1.1×10⁸ and 8.6×10⁹particles·g^‑1, respectively. First wash and rinse of textiles containing Ag NM released 0.5 to 35% of the initial elemental Ag-concentration while textiles containing TiO₂ NM released 0.01 to 3.4% of the initial elemental Ti-concentration. Incineration produced mainly soot at yield ranging from 1 to 39wt% where NM additives may be present depending on the incineration conditions. The characteristics of the released particles varied from consisting of pure NM to fully matrix-embedded NM depending on the products and processes. The results from this study form the basis for a quantitative release library for products containing nanomaterials. We concluded that the release assessment field should harmonize the test procedures and data reporting, including quantification of the amount of nanomaterials released when possible. This would improve the applicability of the data to measure and model human and environmental exposure to nanomaterials and the associated risks.