A Pilot Study on How Microplastic Polluted Rainfall Infiltrates Commonly Eaten Leafy Vegetables

Abstract

Microplastics found in the human body have been reported to compromise tissue integrity, damage organs, and contribute to inflammation and carcinogenesis. Recent research indicates that microplastics also reduce photosynthetic efficiency by approximately 10% across terrestrial, aquatic, and freshwater ecosystems. This reduction has significant implications, potentially leading to an annual loss of up to 360 million metric tons of crops and nearly 24 million tons of seafood, which could impact food availability for roughly 123 million adults. In response to these concerns, this pilot study employed a floating disc assay to quantitatively assess the infiltration of rigid micro- and nano thermo-amino particles (MNPPs) into the foliage of four representative vegetable species: Basella alba (Malabar Spinach), Capsicum chinense (Habanero), Brassica rapa (Bok Choy), and Phaseolus vulgaris (String Beans). The crops were grown organically in Amityville, New York, an area marked by substantial industrial activity. The primary aim was to determine whether rainfall facilitates the entry of MNPPs, ranging in size from 1000 nanometers to 5 micrometers, into leaf tissue through photosynthesis, respiration, and cuticular absorption. Both adaxial and abaxial surfaces of leaf discs were analyzed before and after exposure to MNPPs using a LABOMED CxL clinical microscope. The findings indicate that MNPPs can penetrate leaf structures during both photoperiod (photosynthesis) and scotoperiod (respiration), irrespective of whether the stomata are closed. These findings reveal a previously unidentified route for plastic pollutants to enter the human food chain.