Characterization of Exposures to Micro- and Nanoplastics
Characterization of Exposures to Micro- and Nanoplastics
Project Collaborators:
Ambient and indoor air sampling have revealed the ubiquitous presence of plastic particles of fibrous or spherical morphologies in a wide range of sizes that spans the submicrometer through tens of micrometers scales. For plastics that are encountered in air, the first step in assessing health hazards is to develop knowledge regarding their concentrations and size distributions in the airborne state. There is a dearth of information regarding the morphology, size, and composition of airborne plastic particles from both the indoor and outdoor environments.
In order to begin an assessment of possible health effects of airborne plastics – focusing on micro- and nanoplastics (MNPs) – it is essential to characterize their aerodynamic diameter and aspect ratio, as this determines if particles can get into the respiratory tract at all and, if so, where they might deposit. Polymer composition can affect particle shape and other characteristics like effective density, all of which can determine the aerodynamic behavior of aerosols. For MNPs, there are significant knowledge gaps regarding these factors, in particular about aerodynamic behavior. Our group has optimized sampling methods and collected particles from various indoor and outdoor environments, demonstrating the presence of human-respirable and larger particles whose morphologies and dye staining patterns are suggestive of polymeric origins, i.e., uptake of Nile red stain. With support from the American Chemistry Council, we are currently working to characterize the morphology, amount, chemical identity, and size distribution (physical dimensions, aerodynamic) of the collected MNPs. We are measuring total mass concentrations, number concentrations, and aerodynamic sizes; characterizing particle morphology; and identifying the collected polymer species. A key focus of this work will be on human-respirable MNPs.
We are also part of the Lake Ontario Center for Microplastics and Human Health in a Changing Environment (NIH/NSF), where we are working to improve our understanding of human exposure to MNPs in and around Lake Ontario and to learn how persistent organic pollutants (POPs) and metals modify their toxicity. We are collecting respirable PM samples at different locations and distances from the Lake Ontario shoreline at different times of year in parallel with water sampling in order to determine if any lake water-derived respirable MNPs are present. The data obtained from these sampling campaigns will be shared across the Center to be incorporated in the global MNPs transport model. We are taking advantage of unique optical imaging and machine learning tools available via the University of Rochester’s Institute of Optics to identify the particulates that are captured via air sampling to assess the distributions of polymer type and physical dimensions (length, width). We will also use SEM and optical imaging in order to gain information about the morphology, optical characteristics (e.g., color, birefringence) and physical size distributions of collected particles. ICP-MS will be used to analyze for metal content. Lastly, we will test the cytotoxicity and bioactivity of the collected MNPs in cultured lung cells (BEAS-2B, SAEC, A549). Results with air samples will be compared with water samples collected in the same area as a means to estimate the level of bioactivity and assess water-to-air transfer of MNPs.