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

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.

Potential scenarios for nanomaterial release and subsequent alteration in the environment

“…One of the physical processes that will influence the final destination of the PM-ENM is abrasion (process 8) or mechanical erosion. Abrasion is the process by which physical forces, such as turbulent fluid regimes or strong collision of solid materials, induce the breakdown of the original material and may lead to the release of PW-ENM-or PW-ENM-containing particles in different shapes and sizes [48][49][50][51][52]. Shear stress estimations may indicate the final shape and size of the PW-ENM after undergoing abrasion processes.…”

Human health hazards of persistent inorganic and carbon nanoparticles

“…Persistent nanoparticles are also increasingly engineered for a variety of applications [1][2][3][8][9][10][11][12][13][14][15][16][17][18][19], and references therein]. Engineered nanoparticles in this category are often composed of the substances indicated in Box 1 [1][2][3][8][9][10][11][12][13][14][15][16][17][18][19], and references therein].…”

“…Engineered nanoparticles in this category are often composed of the substances indicated in Box 1 [1][2][3][8][9][10][11][12][13][14][15][16][17][18][19], and references therein].…”

“…An example is the loss of nanoparticles from Ag nanoparticle coated textiles during washing [11, and references therein]. Another case in point is the release of TiO 2 from polymeric matrices linked to polymer degradation [12]. It may also be that particles released from the material with embedded nanoparticles do contain other substances besides the embedded nanoparticles, but are still nanoparticulate [8,[10][11][12], and references therein].…”

“…Another case in point is the release of TiO 2 from polymeric matrices linked to polymer degradation [12]. It may also be that particles released from the material with embedded nanoparticles do contain other substances besides the embedded nanoparticles, but are still nanoparticulate [8,[10][11][12], and references therein]. It might furthermore be that the embedding is such that nanoparticle release from nanocomposites does not specifically concern the nanoparticles included in the product, but is rather linked to changes in product characteristics such as density.…”