Cooking oil is derived from oil seeds, fruit pulp (palm), or animal fat — butter and lard being the main animal-derived examples. The most widely traded cooking oils by volume are palm oil, soybean oil, sunflower oil, palm kernel oil, rapeseed (canola) oil, peanut oil, cottonseed oil, coconut oil, and olive oil. Global demand keeps growing, and a large share of it moves by sea in parcel tankers and portable/ISO tanks rather than in packaged retail form.

This article looks at cooking oil from three separate compliance angles that shippers, tank operators, and surveyors tend to conflate: (1) whether it is dangerous goods at all, (2) the environmental and quality controls that apply to it as a bulk liquid cargo, and (3) what happens to waste cooking oil generated on board once the voyage is over.

1. Why Cooking Oil Is Not Dangerous Goods

Under the IMDG Code, a liquid is classified as Class 3 Flammable Liquid when it gives off a flammable vapour at or below 60°C closed-cup (equivalent to 65.6°C open-cup). Culinary oils sit well above that line — reported flash points for common cooking and vegetable oils vary by source and refinement level, but consistently fall somewhere in the 200°C–330°C region, several times the Class 3 threshold. That gap is why cooking oil, as a straightforward foodstuff cargo, does not appear anywhere in the Dangerous Goods List.

There is a classification nuance worth checking explicitly rather than assuming. Some oils and fats — palm oil and palm stearin in particular — solidify at ambient temperature and must be kept heated to remain pumpable, typically in the 40–60°C range. The IMDG Code’s “elevated temperature substance” concept (which brings UN 3257, Elevated Temperature Liquid, N.O.S., into play) is triggered by either of two conditions: the liquid is at or above 100°C, or it has a flash point at or above 37.8°C and is intentionally heated and offered for transport at or above its own flash point. Ordinary heated edible oil cargoes fail both tests — they’re heated only to 40–60°C, nowhere near 100°C, and nowhere near their own (very high) flash point — so UN 3257 does not apply to them in normal trade. The check is still worth making by name if a specific fat, tallow, or wax blend genuinely requires higher heating temperatures to stay liquid.

Under 49 CFR, the same logic holds: cooking oils fall well outside the flammable liquid flash-point band (≤60°C, or the domestic “combustible liquid” band of 60–93°C which itself is not internationally regulated), so they are not hazmat for U.S. domestic transport either. Being outside Class 3 does not mean cooking oil is unregulated cargo, though — it simply moves the compliance burden from dangerous goods rules to food-safety, quality, and marine-pollution rules instead.

2. MARPOL Annex II and the IBC Code: The 2021 “Persistent Floater” Rules

This is the single biggest regulatory change affecting cooking oil carriage since the original version of this article, and it was still working its way into force at the time that version was published.

Amendments to MARPOL Annex II introduced mandatory prewash requirements at the port of unloading for certain high-viscosity or low-melting-point “persistent floating” products — substances with a viscosity of 50 mPa·s or more at 20°C, and/or a melting point of 0°C or higher. These amendments were adopted as Resolution MEPC.315(74) alongside a parallel revision of the IBC Code (Resolution MEPC.318(74)), both entering into force on 1 January 2021.

The prewash-and-discharge-to-shore requirement applies specifically to products such as fish oil, olive oil, palm oil, highly-refined paraffin wax, rice bran oil, and sunflower seed oil, among others. The obligation itself sits in MARPOL Annex II regulation 13.7.1.4, and it is triggered when the vessel discharges within one of four separately defined regional sea areas set out in regulation 13.9: North West European waters (the North Sea, Irish Sea, Celtic Sea, and English Channel, with their approaches, plus part of the North East Atlantic immediately west of Ireland), the Baltic Sea area, Western European waters (a distinct area covering the coastlines of the UK, Ireland, Belgium, France, Spain, and Portugal from the Shetland Islands southward), and the Norwegian Sea. Outside those four defined areas, the standard IBC Code discharge provisions for the applicable pollution category still apply.

Because the amended Chapter 21 criteria led to a full reassessment of carriage requirements across Chapters 17 and 18 of the IBC Code, ship type assignments changed for a range of products — some upgraded from Ship Type 3 to Type 2, or Type 2 to Type 1, with a smaller number downgraded — and a new Certificate of Fitness or NLS Certificate had to be issued reflecting the revised entries. Any tank vessel regularly in the edible oil trade should have confirmed its current CoF reflects the post-2021 entries; that’s been settled for over five years now, but still worth a documentary check on older tonnage.

3. Food-Grade Tanks and Previous-Cargo Restrictions

Cooking oil can only be carried in food-grade tanks, and the single most important check before loading is what the tank carried previously. Even a tank that appears visually clean can retain contamination trapped in coatings or hard-to-reach fittings from an earlier cargo.

FOSFA’s standard contract terms require that the immediate previous cargo appear on the List of Acceptable Previous Cargoes, and that the two cargoes carried before that must not appear on the List of Banned Immediate Previous Cargoes. The Codex Alimentarius Committee on Fats and Oils (CCFO) and the U.S. National Institute of Oilseed Products (NIOP) publish parallel lists used in different trade terms, and EU import rules impose their own conditions depending on whether the oil is destined for further processing.

FOSFA List of Banned Immediate Previous Cargoes (effective 1 September 2024)

Representative entries from the current list — always check the live FOSFA document before qualifying a tank, as this list is revised periodically.

Two restrictions apply beyond the immediate previous cargo: leaded products must not have been carried as any of the three previous cargoes, and Ethylene Dichloride and Styrene Monomer must not have been carried as any of the three previous cargoes in organically coated tanks, nor as the last cargo in stainless steel or inorganically coated tanks.

4. Used Cooking Oil: A Cargo Category of Its Own

Used Cooking Oil (UCO) and its methyl ester derivative (UCOME) both appear on FOSFA’s banned previous cargo list — and this goes back further than it might appear. A FOSFA circular effective 1 April 2016 added UCO and UCOME to the banned list, and both have remained on every subsequent edition since, including the current September 2024 revision. The effect is that a tank which last carried UCO/UCOME cannot qualify as suitable for an edible oil cargo without further cleaning and requalification, keeping the “waste” and “food-grade” oil supply chains institutionally separated at the tank level — a distinction FOSFA built in a full decade before SAF-driven demand made it commercially urgent.

That separation matters more today than it did when this article was first written, because UCO has become a commercially significant — and fraud-exposed — commodity in its own right, driven by biodiesel blending mandates and Sustainable Aviation Fuel (SAF) demand. Europe’s own UCO collection cannot keep pace with demand, so the region now relies heavily on imports, and the price premium attached to “waste-derived” feedstock creates a commercial incentive for some suppliers to mislabel virgin oils — palm oil in particular — as used oil. Regulators have opened multiple inquiries into this: the European Commission examined biodiesel-import fraud allegations from Germany and concluded in July 2025 that, while it identified systemic weaknesses in how voluntary certification schemes conduct their audits, the evidence gathered did not allow it to confirm that fraud had actually occurred — an important distinction from claims sometimes made about that investigation. Separately, the US EPA has opened its own inquiry into potentially fraudulent Chinese-origin UCO entering the US biodiesel supply chain.

Concrete certification fraud has been documented, though on a smaller and more specific scale than headline figures sometimes suggest. In May 2025, Germany’s Federal Office for Agriculture and Food permanently blocked a UAE-registered producer, EcoSolution Limited, from its national biofuels database after finding strong indications the company’s claimed production facility did not exist; the sustainability certificates behind it had been audited by a Latvia-based certifier, which the accreditation body ISCC had already suspended for lack of cooperation with its integrity programme. Cases like this are a useful reminder that “certified” paperwork is a starting point for scrutiny, not proof.

For anyone qualifying tanks or auditing cargo documentation in the edible oil trade, the practical takeaway is unchanged by the exact fraud statistics in dispute: treat any parcel represented as UCO or UCOME with the same previous-cargo scrutiny FOSFA already requires, and be alert to sustainability/mass-balance paperwork that isn’t backed by independent verification, since current analytical methods generally cannot prove by chemistry alone whether a diesel-range biofuel came from waste oil or virgin oil, leaving compliance resting heavily on documentation and audit trails.

5. Dietary and Religious Certification

Beyond the FOSFA/Codex/NIOP previous-cargo framework, buyers frequently require Halal or Kosher certification for the cargo and, in some cases, for the carrying tank’s cleaning history. These certifications sit outside MARPOL and the IBC Code entirely — they are contractual and religious-authority requirements layered on top of the cargo quality regime, and should be confirmed with the specific certifying body rather than assumed from the previous-cargo list alone.

6. Onboard Storage and Quality Preservation

Cooking oil degrades on exposure to light, heat, and oxygen. To slow oxidation during the voyage, the vapour space above the cargo is normally filled with an inert gas — almost always nitrogen — a practice known as nitrogen blanketing or tank blanketing. This is a quality-preservation measure rather than a safety requirement in the DG sense, but it is standard practice across the edible oil tanker trade.

7. MARPOL Annex V: What Actually Happens to Waste Cooking Oil On Board

MARPOL Annex V defines garbage to include food waste, domestic and operational waste, all plastics, cargo residues, incinerator ashes, cooking oil, fishing gear, and animal carcasses generated during a ship’s normal operation. Garbage Record Books list cooking oil as its own lettered category, separate from food waste. Regulation 3 of the revised Annex V states plainly that the discharge into the sea of cooking oil is prohibited.

The only exception is Regulation 7, which permits discharge solely for emergencies affecting the safety of the ship or persons on board, or as an accidental loss resulting from damage to the ship — not as a routine disposal method. IMO guidance under MEPC.219(63) further notes that, because port reception facilities differ in what they can process, cooking oil should generally be kept segregated from other garbage streams — for example in dedicated drums — ahead of landing ashore.

This is a meaningful distinction from food waste, which — comminuted to pass a 25 mm screen — may be discharged 3 nautical miles or more from the nearest land while the ship is en route, or 12 nautical miles or more if not comminuted. Cooking oil gets none of that latitude. In practice this means:

• Waste cooking oil generated in galleys must be collected and retained on board, never discharged overboard regardless of distance from land.
• It should be stored separately from other garbage categories to avoid contaminating a stream that might otherwise qualify for at-sea discharge or simpler shore handling.
• It must be landed to port reception facilities, logged in the Garbage Record Book under its own category, and supported by disposal receipts.
• Special Areas (Mediterranean, Baltic, Wider Caribbean, Antarctic, and — since 1 January 2025 — the Red Sea) do not change this: cooking oil discharge is prohibited inside and outside Special Areas alike.

8. Practical Compliance Checklist

Cooking oil sits in an unusual compliance position: entirely outside dangerous goods regulation, yet subject to a dense layer of environmental, quality, and — increasingly — anti-fraud controls that have only tightened since 2021. Getting classification right is the easy part. Getting the previous-cargo history, the MARPOL Annex II discharge obligations, and the Annex V disposal rule right is where most of the operational risk actually sits.