Quantifying Release of Nano- and Advanced Materials: Determining a Lower Detection Limit J. Brame * , A. Poda * , E. Alberts ** , C. Jackson *,*** , and A.J. Kennedy * * US Army Engineer Research and Development Center, Environmental Laboratory, 3909 Halls Ferry Rd. Vicksburg, MS, USA, Jonathan.A.Brame@usace.army.mil ** HX5 LLC, 212 Eglin Pkwy. Ft Walton beach, FL, USA *** Alcorn State University, Department of Chemistry, Lorman, MS, USA ABSTRACT The same unique properties of Manufactured Nanomaterials (MNs) and Advanced Materials (AdM) that make them desirable for new product applications may also increase their environmental health and safety (EHS) uncertainty [1]. Therefore, it is anticipated that MNs/AvMs will have a high risk prioritization under the reformed Toxic Substances Control Act (Frank Lautenberg Chemical Safety for the 21st Century Act) [2], leading to potential delays in production. EHS testing of MNs—and increasingly AvMs— 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 [3]. Truly quantifying the risk of these materials requires additional knowledge about how the product is used and the release of MNs/AdMs from the product during use, including any transformations that occur during those releases; however, these release testing processes constitute one of the least understood sources of EHS risk for MN/AdM-enabled products [4], and therefore contribute significantly to the EHS uncertainty. Even incremental improvements in release and exposure quantitation have been encumbered by analytical gaps related to measurement of MN release. In this report, we show a novel calibration method we have developed to establish a “detection limit” 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/AdMs, particularly in regard to providing some level of confidence in cases where no material is released (i.e., trying to prove a negative). Keywords: Abrasion, Nanomaterials, Release Testing, environmental health and safety, detection limit, quantification, exposure 1 INTRODUCTION Nanomaterials are increasingly being used in commercial products to take advantage of nano-specific properties such as strength, electrical and thermal conductivity, anti-microbial capability, optical and fluorescent capacity, and catalytic ability [5]. Although these materials and the products that utilize them hold great potential, that promise is tempered by possible environmental health and safety (EHS) risks of Manufactured Nanomaterials (MNs)[3,6-8]; and as is often the case, regulatory guidance lags technology development. Furthermore, while some EHS hazards exist, they often pose little hazard until the MN is actually released from the matrix within which it is incorporated. In some cases this could be a mixture or liquid dispersion with high release potential, while in other cases materials may be embedded in solid polymer, epoxy or cement-type materials from which the presumed potential for release is substantially lower. Thus it is crucial to understand both the hazard and the exposure to truly quantify the EHS of MNs [9-10]. Several recent studies have attempted to bridge the critical knowledge gap of MN release from nano-composite materials using mechanical abrasion techniques. Release of matrix-bound carbon nanotubes (CNTs) from a nanocomposite required a combination of UV-induced weathering and physical abrasion [11]. Several other studies of general MNs found some level of free, individual release under heavy mechanical stress [12-15], while others found no individual MNs released under similar mechanical stress conditions [16-19]. Many of these studies identified difficulty in generating reproducible results during these mechanical abrasion studies [13,18-19] due to variability in material, abrasion and aerosol sampling as a significant issue in determining release of ENMs. Even when nano-sized particles are identified in a particle size distribution, it can be difficult to determine if they are the ENMs included in a composite formulation or simply small particles of the composite matrix released during abrasion [20,21]. These issues highlight an important need for increased system characterization techniques during mechanical release studies. While some authors provide detailed descriptions of quantification procedures and detection limits for MNs in recovered powders [11], in situ particle measurement techniques such as condensation particle counters (CPS), fast mobility particle sizers (FMPS) and impact particle collectors (IPCs) are rarely characterized for sensitivity and detection limits beyond nominal manufacturer values. In this proceeding we describe a procedure to characterize the lower detection limit for particle concentration (#/cm 3 ) during MN release testing 325 Advanced Materials: TechConnect Briefs 2017