PARTNERSHIP: Crop exposure to micro-nanoplastics and potential impact on human nutrition and health

Proposed Research: In this project we will develop model environmentally relevant micro-nano-plastics using state of the art life cycle material degradation platforms. We also study MNPs as carriers of other EPs to evaluate their potential to increase the bioavailability of inorganic and organic pollutants in plants and in the human intestine. We hypothesize that the effects of MNPs on bioavailability of EPs are dependent on both the size and polymer of the MNP. The two model polymers to be studied (PVC and PE) are of particular relevance in agriculture, since PVC is a plastic material widely used to construct hydroponic systems, while films of PE are vastly utilized as covers in open fields to insulate soil.The project consists of three interconnected AIMs:Aim 1: Synthesis, Characterization, and Environmental Pollutant (EP) Interactions of Model Environmental MNPs. A major roadblock in bioactivity studies of MNPs is the lack of environmentally relevant MNPs, which has limited previous studies to primary MNPs such as polystyrene beads. Such simplistic model MNPs are not environmentally relevant in terms of physicochemical and morphological properties and the associated bioactivity data are of limited utility for risk assessment. We will use existing life cycle material degradation platforms at NAMC to generate environmentally relevant reference MNPs of two highly produced polymers commonly used in agricultural applications, polyethylene (PE) and polyvinyl chloride (PVC). These platforms include: 1) A thermal degradation system that will be used to simulate municipal incineration of plastics; and 2) A combined cryomilling and UV/photo-ageing platform that will be used to simulate photo-oxidative and mechanical degradation of plastics in the environment. These model MNPs will be fully characterized using state-of-the-art analytical methods available in our labs. We will also assess the sorption and concentration of EPs by the model MNPs from water containing environmentally relevant concentrations of a model PFAS (PFOS), a model pesticide (boscalid), and toxic metals (As, Cr, Pb).Aim 2: Assessment of Accumulation and Impact of MNPs and Sorbed EPs in Plants Under Hydroponic and Greenhouse Soil Conditions. We will study environmentally relevant MNPs and size-effects on the bioavailability of inorganic (As, Cr, Pb) and organic (boscalid and PFOS) compounds. Plants will be grown in hydroponics and soil and exposed to MNPs generated in Aim 1, in the presence or absence of EPs. Lettuce and wheat will be used as model monocot and dicot species, and our system will evaluate effects in both hydroponic and greenhouse soil systems for each. Environmentally relevant concentrations of MNPs and EPs will be used to derive dose-response relationships. In addition, the NJIT team will develop a pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) method for the robust analysis and quantification of secondary MNPs as part of this Aim.Aim 3: Assessment of Uptake and Translocation/Bioavailability of MNPs and Sorbed EPs in a Triculture Small Intestinal Epithelium. We will use a three-phase (oral, gastric, small intestinal) simulated digestion coupled with a transwell triculture cellular model of the small intestinal epithelium to assess the health effects of MNP ingestion. We will assess intestinal epithelial cellular uptake and translocation of the model MNPs alone, as well as the effect of MNPs on the bioaccessibility and bioavailability of EPs. Cellular and molecular mechanisms that could underlie or lead to impaired intestinal boundary function and increased EP absorption in the presence of MNPs will be assessed