Plastics contamination of store-bought rice

Area of Science:

• Environmental Science
• Food Science
• Analytical Chemistry

Background:

• Rice is a global staple food for over half the world's population.
• Microplastic contamination in food sources is a growing environmental and health concern.
• Understanding plastic levels in rice is crucial for assessing dietary exposure.

Purpose of the Study:

• To quantify mass concentrations of selected plastics in commercially available rice.
• To investigate factors influencing plastic contamination, including packaging and processing.
• To estimate human intake of plastics through rice consumption.

Main Methods:

• Quantification of six plastic types (polyethylene, PET, PMMA, polypropylene, polystyrene, PVC) using pressurized liquid extraction and pyrolysis-GC/MS.
• Comparison of plastic levels in rice from different packaging types (paper vs. plastic).
• Assessment of the impact of washing and shaking on plastic contamination.

Main Results:

• Polyethylene, polypropylene, and PET were detected in rice samples, with polyethylene being the most frequent (95%).
• No significant difference in plastic concentration was found between paper and plastic packaging.
• Washing rice significantly reduced plastic contamination, and instant rice had fourfold higher plastic levels.
• Preliminary intake estimates for Australians were 3.7 mg/serve (unwashed) and 2.8 mg/serve (washed).

Conclusions:

• Commercial rice is a source of microplastic contamination, particularly polyethylene.
• Industrial processing, as seen in instant rice, appears to increase plastic levels.
• Washing rice is an effective method to reduce microplastic intake from this staple food.