Plastics contamination of store-bought rice

Abstract

This study investigated mass concentrations of selected plastics in store-bought rice, the staple of more than half the world's population. Polyethylene, polyethylene terephthalate, poly-(methyl methacrylate), polypropylene, polystyrene and polyvinyl chloride were quantified using pressurized liquid extraction coupled to double-shot pyrolysis gas chromatography/mass spectrometry. Polyethylene, polypropylene and polyethylene terephthalate were quantifiable in the rice samples with polyethylene the most frequently detected (95%). There was no statistical difference between total plastic concentration in paper and plastic packaged rice. Shaking the rice in its packaging had no significant difference on the concentration of plastics. Washing the rice with water significantly reduced plastic contamination. Instant (pre-cooked) rice contained fourfold higher levels of plastics, suggesting that industrial processing potentially increases contamination. A preliminary estimate of the intake of plastic through rice consumption for Australians established 3.7 mg per serve (100 g) if not washed and 2.8 mg if washed. Annual consumption was estimated around 1 g/person.

Keywords: Dietary intake; Food; Human exposure; Microplastics; Nanoplastics; Packaging.