On the Lifecycle of Nanocomposites: Comparing Released Fragments and their In‐Vivo Hazards from Three Release Mechanisms and Four Nanocomposites

TLDR

Nanocomposites dominate consumer nanomaterials, are presumed low risk, yet emerging exposure data reveal unknown nanospecific physiological effects. This study systematically investigates the exposure and potential hazards of thermoplastic and cementitious nanocomposites. The authors generate sanding aerosols up to the nuisance dust limit and perform in‑vivo rat instillation to compare degradation products from abraded nanocomposites, abraded matrix, and pure nanofiller. Results show pigment chalking occurs, mechanical use does not release free nanofillers (none detected above 100 ppm), sanding powders retain nanofillers, and in‑vivo hazards are indistinguishable with or without nanofiller.

Abstract

Abstract Nanocomposites are the dominating class of nanomaterials to come into consumer contact, and were in general assumed to pose low risk. The first data is now emerging on the exposure from nanocomposites, but little is yet known about their hypothetical nanospecific physiological effects, giving ample room for speculation. For the first time, this comprehensive study addresses these aspects in a systematic series of thermoplastic and cementitious nanocomposite materials. Earlier reports that ‘chalking’, the release of pigments from weathered paints, also occurs for nanocomposites, are confirmed. In contrast, mechanical forces by normal consumer use or do‐it‐yourself sanding do not disrupt nanofillers (nanoparticles or nanofibers) from the matrix. Detailed evidence is provided for the nature of the degradation products: no free nanofillers are detected up to the detection threshold of 100 ppm. Sanding powders measuring 1 to 80 μm in diameter are identified with the original material, still containing the nanofillers. The potential hazard from aerosols generated by sanding nanocomposites up to the nuisance dust limit is also investigated. In‐vivo instillation in rats is used to quantify physiological effects on degradation products from abraded nanocomposites, in comparison to the abraded matrix without nanofiller and to the pure nanofiller. In this pioneering and preliminary evaluation, the hazards cannot be distinguished with or without nanofiller.