Oil-Coated Nanoplastics Induce Rapid Membrane Disruption and Severe Intestinal Injury

Area of Science:

• Environmental Science
• Materials Science
• Toxicology

Background:

• Plastic food containers are widely used, especially in food delivery.
• Concerns exist regarding micro- and nanoplastic (MNP) release from these containers into food.
• Oil-rich foods may exacerbate MNP release and associated health risks.

Purpose of the Study:

• To quantify MNP release from common plastic containers (polypropylene and polyethylene-coated) when heated with cooking oil.
• To assess the cytotoxicity and in vivo effects of oil-derived MNPs.
• To establish safety thresholds and compare them with human exposure levels.

Main Methods:

• Microwave heating of plastic containers with cooking oil and water.
• Quantification of MNP release using particle counting.
• Cytotoxicity assays (IC50) on cell lines.
• In vivo studies using mice to assess intestinal damage and immune response.
• Benchmark dose modeling for safety threshold determination.

Main Results:

• Cooking oil dramatically increased MNP release (up to 1.52 × 10^14 particles/L) from PP and PE containers within 3 minutes of microwave heating, ~125-fold higher than with water.
• Co-release of plastic additives and heavy metals increased up to 309-fold.
• Soybean oil-derived PP nanoplastics showed 4x higher cytotoxicity (IC50 = 18.7 µg/mL) compared to water-derived particles (IC50 = 77.1 µg/mL).
• Oil-derived nanoplastics caused severe intestinal barrier damage and mucosal immune dysfunction in mice.
• Modeled human gastrointestinal MNP burdens exceeded molecular safety thresholds by up to 1107-fold.

Conclusions:

• Heating oil-contact plastics significantly elevates MNP release and co-contaminant exposure.
• Oil-derived MNPs exhibit enhanced cytotoxicity and induce adverse in vivo effects on the gut barrier and immune system.
• Current human MNP exposure levels may exceed established molecular safety thresholds, highlighting risks associated with plastic food packaging.