J. Brame, A. Poda, E. Alberts, C. Jackson, A. Kennedy
US Army Engineer Research and Development Center,
Keywords: release, abrasion, characterization, detection, nano
Summary:The same unique properties of Manufactured Nanomaterials (MNs) and Advanced Materials (AMs) that make them desirable for new product applications may also increase their environmental health and safety (EHS) uncertainty , leading to high risk prioritization under the reformed Toxic Substances Control Act (Frank Lautenberg Chemical Safety for the 21st Century Act) , and potential delays in production. EHS testing of MNs—and increasingly AMs—historically began with focus on assessing potential for toxic impacts of pristine materials exposed directly to model organisms, and has since expanded to include more complex environmental matrices and understanding of fate and transport of these materials in the environment . Truly quantifying the risk of these materials requires additional knowledge about how the product is used and the release of MNs/AMs from the product during use, including any transformations that occur during those releases; however, these release testing processes constitute one of the least studied sources of EHS risk for MN/AM-enabled products , and therefore contribute significantly to the EHS uncertainty. Abrasion testing is an aggressive form of release testing that represents a “worst-case”, conservative model to identify potential release and entry of MNs/AMs into the environment, where they can interact with human and ecological receptors. In this presentation, we use a modified Taber abrader system to test release of MNs from several case studies, including an anticorrosive paint containing carbon nanotubes, a self-cleaning cement that contains titanium dioxide, a nitrocellulose material, and several reference materials (glass, cardboard, plastic) . Results (Figure 1) show the capability of the analytical methods for assessing and characterizing released materials, and provide relevant examples of how to use this type of testing to make risk-informed decisions. In addition to the EHS implications of this release testing, we also show a novel calibration method we have developed to establish a “limit of detection” for identification of released NMs (Figure 2). This analysis is the first of its kind, and starts to resolve some of the uncertainty inherent in risk assessment and EHS impacts of MNs/AMs, particularly in regard to providing some level of confidence in cases where no material is released (i.e., trying to prove a negative).