Short answer: for bag‑to‑food use, PE (HDPE/LDPE) bags shed fewer microplastics than TÜV‑AUSTRIA‑certified compostable bags (which are typically PLA/PBAT blends). Biodegradable films fragment faster and generate more MPs under water/UV or abrasion; PE is slower to fragment, especially at room temperature and without heat.
Why I’m saying that
-
Head‑to‑head evidence in water: A Water Research study comparing PBAT (biodegradable) vs LDPE (PE) found “a much larger quantity” of microplastics formed from PBAT than from LDPE across freshwater and seawater conditions; UV accelerated PBAT shedding.
-
Composting tests: In lab composting (ISO 20200 conditions), microplastics <2 mm were detected from some biodegradable products in the undersieve, while conventional PE/PS remained as larger macrofragments (i.e., didn’t turn into micro‑sized pieces over the test window). That indicates biodegradables fragment to small particles more readily.
-
Direct use matters: Heating plastics drives particle release; keeping any bag cold and brief‑contact minimizes MPs. (Microwaving or hot liquids vastly increases shedding across plastics.)
Important context (if you’re worried about compost → crops): In finished compost from well‑run plants, PE/PP fragments dominate what’s found, while certified compostable pre‑collection bags can disintegrate with very low residual microfragment counts (though not zero). That affects environmental loading more than direct food exposure from a bag.
Bottom line for your choice:
- If your only goal is minimizing MPs getting into food from the bag itself, pick PE and avoid heat.
- If you’re thinking about the compost stream, use certified compostable only where your composter actually accepts and fully processes them; that yields less persistent plastic in compost than PE.
Short answer:
At the same small size (esp. sub‑micron) and shape, PBAT micro/nanoplastics are about as likely to get into cells as PE, PP, and PET—because size, surface charge, and the protein corona govern cellular uptake far more than the base polymer. Where PBAT likely differs is what happens after uptake: as a polyester, it’s more hydrolysable than polyolefins (PE/PP), so once inside lysosomes it probably clears faster (less time “stuck”) than PE/PP, and faster than PET as well, though direct human‑cell head‑to‑head data are still sparse.
What controls “getting stuck” (two parts)
A) Getting in (cellular uptake)
Dominant factors: particle size (nano ≫ micro), surface charge, and the protein corona that forms during digestion or in biological fluids. Digestion‑derived coronas can increase macrophage uptake of otherwise neutral particles; this effect is much stronger than differences among common polymers.
Examples in human models (polymer type still not the main driver):
PE (1–4 µm) shows measurable transport across Caco‑2 intestinal monolayers—demonstrating that even buoyant polyolefins can cross a gut‑cell barrier at small sizes.
PET nanoplastics have been visualized inside cells (confocal), confirming internalization at nanoscale.
For PBAT specifically: Direct, head‑to‑head human‑cell uptake data vs. PE/PP/PET are limited. However, PBAT (a polyester) will acquire protein coronas much like PET/PE/PP, so uptake at a given size/charge should be in the same ballpark. Recent work on photo‑aged PLA/PBAT fragments shows macrophage toxicity comparable to—or greater than—conventional plastics, consistent with effective interaction and uptake by immune cells.
Takeaway on uptake: If you compare equal particles (e.g., ~100–500 nm, similar charge), PBAT ≈ PET ≈ PE ≈ PP for likelihood of entry. Polymer chemistry is a secondary factor next to size/charge/corona.
B) Staying in (intracellular persistence once taken up)
Polyesters can hydrolyze. PBAT is an aliphatic–aromatic polyester with ester bonds that can be cleaved; dedicated PBAT‑degrading esterases are known in microbes, and polyesters are generally more susceptible to hydrolysis than polyolefins. While direct human lysosomal degradation rates for PBAT aren’t established, the chemistry points to greater degradability than PET and far more than PE/PP.
Polyolefins persist. PE/PP have C–C backbones with no hydrolysable bonds; there are no known enzymes (microbial or mammalian) that efficiently depolymerize them, so once internalized they are expected to be more persistent than polyesters.
Takeaway on persistence: On present evidence and polymer chemistry, the likely order of long‑term “stuckness” inside cells is:
PE ≈ PP (most persistent) > PET > PBAT (least persistent). (Caveat: direct, quantitative human‑cell data comparing these four are still limited.)
Practical implications for you
If your concern is ingestion from food‑contact bags, avoid heat and abrasion with any plastic; those conditions produce the most micro/nanoplastics and promote uptake‑relevant size ranges. (This matters far more than whether the bag is PBAT, PE, PP, or PET.)
If your concern is what happens after particles get into cells, PBAT’s polyester chemistry suggests shorter intracellular residence than PE/PP, and likely shorter than PET, though real‑world human‑cell comparisons are still emerging.
Bottom line (put simply)
Chance of getting in: About the same for PBAT, PE, PP, PET at the same small size and charge; size/corona dominate.
Chance of staying stuck: Lower for PBAT (and probably lower than PET), higher for PE/PP, based on degradability of the polymer backbone.
If you want, tell me the particle size range or use scenario you care about (e.g., nanoplastics from hot food contact vs. ambient handling), and I’ll map it to the most relevant uptake/persistence evidence.