PFAS in Cooking Oil: When the Plastic Doesn't Come From the Bottle

The mismatch that matters

Most contamination stories are boring because the answer is obvious: plastic packaging, plastic in the product. This one is interesting precisely because the numbers do not line up that way.

A third-party test of a widely sold extra virgin olive oil reported two microplastic particles per millilitre — one PTFE and one rubber, roughly thirty per tablespoon. The finding that matters is not the count. It is the identification. PTFE is not what squeeze bottles are made of. They are typically PET or HDPE. If PTFE is in the oil, it did not come from the container the oil was sold in.

So where does PTFE live in the life of a bottle of olive oil? In the equipment. Fluoropolymers are standard throughout food processing — gasket material, valve seats, pump seals, the internal lining of transfer hoses, and non-stick surfaces on machinery that handles sticky or fatty product. Every one of those is a surface that fatty liquid passes over under pressure, at temperature, thousands of litres at a time.

This is a single third-party test rather than peer-reviewed work, and we would not build a health claim on it. But as a direction-finding result it is genuinely useful, because it redirects attention from the thing consumers can see to the thing they cannot.

Why oil is the worst case for any plastic contact

There is a piece of regulatory science that explains this whole category in one sentence, and almost nobody outside food packaging knows it.

When migration from food-contact plastic is tested, laboratories do not use the actual food. They use simulants chosen to represent worst cases: dilute acetic acid for acidic foods, ethanol for alcoholic ones, and olive oil or an equivalent fatty simulant for anything fatty. Fat is in the panel because it is the aggressive one. Non-polar additives — plasticisers, stabilisers, residual monomers — are far more soluble in fat than in water, so a fatty food pulls substances out of a polymer that water would leave alone entirely.

Which means cooking oil is not an ordinary product in a plastic bottle. It is the test simulant, sitting in the packaging, for months. Anything extractable from that bottle has ideal conditions and unlimited time to be extracted. That is true regardless of brand, and it is the strongest argument in the category for glass or tin.

The contaminant that is better documented than PFAS

If you are auditing your cooking oil, the evidence is actually stronger for a different family of chemicals. Phthalates — particularly DEHP — have been repeatedly detected in olive oils in independent laboratory testing, at concentrations in the parts-per-billion range. Phthalates are plasticisers, they are not chemically bound to the polymer, and they are highly fat-soluble. They are, in other words, exactly what you would predict would end up in an oil stored in plastic.

PFAS in edible oils is real but more variable and generally lower. Peer-reviewed measurements put PFOA from 53 pg/g in olive oil to 1,962 pg/g in sunflower oil, while separate testing of Italian olive and peanut oils found PFOA and PFOS below the limit of detection altogether. Two honest readings follow from that: the contamination is not universal, and the oil type matters more than the brand.

What to actually do

• Buy oil in dark glass or tin. This is the one lever you fully control, it removes the longest-duration fat-to-plastic contact in your kitchen, and dark glass helps with oxidation too.
• Decant if you buy plastic. If the format you like only comes in a squeeze bottle, move it into glass at home. Contact time is the variable that matters most.
• Do not store oil near the hob. Warmth accelerates both migration and oxidation, and the cupboard above the cooker is the hottest storage in most kitchens.
• Buy smaller bottles and turn them over faster. Months of storage is the mechanism; a bottle you finish in three weeks has far less of it.
• Do not switch brands on the strength of one test. A single third-party result identifies a direction, not a ranking, and no olive oil brand currently publishes routine microplastic testing — so any brand-by-brand league table you see is largely invented.
• Recognise the limit of consumer choice here. If PTFE is entering oil from processing equipment, packaging changes do not touch it. That is a supply-chain disclosure problem, and the honest answer is that it is not currently solvable from the shopping aisle.

Related: does Graza olive oil have microplastics, olive oil brands ranked, PFAS and forever chemicals explained, and microplastics vs PFAS vs BPA.