Categorization framework to aid exposure assessment of nanomaterials in consumer products

Abstract

Exposure assessment is crucial for risk assessment for nanomaterials. We propose a framework to aid exposure assessment in consumer products. We determined the location of the nanomaterials and the chemical identify of the 580 products listed in the inventory maintained by the Woodrow Wilson International Center for Scholars, of which 37% used nanoparticles suspended in liquids, whereas <1% contained "free airborne nanoparticles". C(60) is currently only used as suspended nanoparticles in liquids and nanosilver is used more as surface bound nanoparticles than as particles suspended in liquids. Based on the location of the nanostructure we were able to further group the products into categories of: (1) expected, (2) possible, and (3) no expected exposure. Most products fall into the category of expected exposure, but we were not able to complete a quantitative exposure assessment mainly due to the lack of information on the concentration of the nanomaterial in the products--a problem that regulators and industry will have to address if we are to have realistic exposure assessment in the future. To illustrate the workability of our procedure, we applied it to four product scenarios using the best estimates available and/or worst-case assumptions. Using the best estimates available and/or worst-case assumptions we estimated the consumer exposure to be 26, 15, and 44 microg kg(-1) bw year(-1) for a facial lotion, a fluid product, and a spray product containing nanoparticles, respectively. The application of sun lotion containing 2% nanoparticles result in an exposure of 56.7 mg kg(-1) bw d(-1) for a 2-year-old child, if the amounts applied correspond to the European Commission recommendations on use of sunscreen.

Potential scenarios for nanomaterial release and subsequent alteration in the environment

“…In most cases, P-ENM are industrially modified to form the PM-ENM that are embedded in final products. The modifications to P-ENM allow them to be homogeneously dispersed or incorporated into the matrix or at the surface of the final product [11]. In many cases, this involves modifying the hydrophilic-hydrophobic properties for the use of P-ENM in organic solvents, modifying surface charge for use with aqueous solvents, or a variety of alterations to manipulate surface reactivity.…”

Silica nanoparticles induce oxidative stress, inflammation, and endothelial dysfunction in vitro via activation of the MAPK/Nrf2 pathway and nuclear factor-&kappa;B signaling

“…4 They have recently been extensively utilized in biomedical and biotechnological fields for biomolecule detection, diagnosis, imaging, drug delivery, gene therapy, and photodynamic therapy. 5,6 As a consequence, human exposure to SiNPs continues to increase in environmental, occupational, and medial settings.…”

A Personal Nanoparticle Respiratory Deposition (NRD) Sampler

“…Therefore, the NPM fraction is a subset of the inhalable particulate matter (IPM) collection efficiency, defined as (1) where d is the particle diameter in μm. (9) The collection efficiency for NPM is given by (2) where F(x) is the cumulative probability density function of the standardized normal variable x, (3) with Γ = 0.04 μm (40 nm), and Σ = 3.9.…”