Food-grade polyethylene (PE) is evaluated against three overlapping but distinct regulatory models. In the European Union, Commission Regulation (EU) No 10/2011 treats PE as a plastic material and controls constituents through an authorised substance list, overall migration limits, and specific migration limits. In the United States, 21 CFR 177.1520 establishes an olefin polymer framework in which the polymer and its adjuvants are assessed through end-test extraction data tied to food type and temperature. In China, GB 4806.7-2016 applies to finished plastic materials and articles. A resin identifier such as LDPE, LLDPE, MDPE, or HDPE does not by itself establish food-grade status. The final article must be tested in a food simulant or extraction solvent that reflects the intended food-contact surface, because low-molecular-weight oligomers, hydrocarbon waxes, catalyst residues, and surface-active additives are the principal migrants. The same PE grade can show different compliance results in blow-moulded bottles, cast film, blown film, injection-moulded caps, and thermoformed trays because thermal and shear history modify the extractable fraction.

Why the 10 mg/dm² overall migration limit behaves differently in thin films and moulded closures

Article 12 of EU 10/2011 sets the overall migration limit at 10 mg of total constituents per dm² of food contact surface area. For articles intended for infants and young children, the limit is expressed as 60 mg/kg in food simulant. The two expressions are not interchangeable for all geometries. A thin PE film with a high surface-area-to-volume ratio is usually assessed against the 10 mg/dm² criterion, while a small moulded closure or a thick-walled container may be assessed against the 60 mg/kg criterion. In practice, laboratories calculate the result according to the actual fill volume and contact area. Migration testing is performed with food simulants selected from Annex III of EU 10/2011. For PE, the typical simulant set includes simulant A (10 % ethanol), simulant B (3 % acetic acid), simulant C (20 % ethanol), and fatty simulant D2 or its permitted alternatives. Because PE is non-polar, aqueous and acidic simulants usually extract little polymer-derived material. The limiting test for PE is often fatty-food simulation, where vegetable oil or a substitute such as isooctane or 95 % ethanol extracts hydrocarbon oligomers, slip agents, and alkyl fragments. Migration methods are drawn from the EN 1186 series for overall migration and EN 13130-1 for specific migration. An incomplete test programme that omits the fatty simulant can overstate compliance for PE films used with oily or fatty foods.

Production-scale conversion can shift the extractables profile even when the incoming resin complies. On a cast-film line using a 75 mm single-screw extruder at melt temperatures between 240 °C and 255 °C, oxidative chain scission forms aldehydes, ketones, and short-chain hydrocarbons that are more mobile than the high-molecular-weight polymer. In HDPE blow moulding, melt temperatures above 230 °C can increase low-molecular-weight hydrocarbon generation, particularly when the screw speed and back pressure are high. These species migrate more readily into fatty simulants than the original resin. The result is that a certified resin can produce a non-compliant finished part after aggressive conversion. Therefore, compliance testing should be carried out on the finished article or on pressed plaques generated under conditions that reflect the thermal and shear history of the production line.

Additive selection in PE food-contact grades is the practical bridge between processing and regulation. Primary antioxidants, secondary antioxidants, acid scavengers, slip agents, and antiblock additives are common. In the EU, each intentionally added substance must be listed in Annex I of EU 10/2011 or otherwise authorised; in China, additives must be in GB 9685-2016 with their specific migration limit or quantity limit; in the United States, additives must be cleared for the intended use through a food-contact regulation or an effective food-contact substance notification. Slip agents such as erucamide and oleamide bloom to the film surface to reduce coefficient of friction. The surface-bloomed layer is directly available for transfer to food and is frequently the main contributor to fatty-simulant migration. Changing from HDPE to LLDPE can alter additive solubility and diffusion. The lower crystallinity of LLDPE increases free volume in the amorphous phase, allowing faster migration of low-molecular-weight additives. A formulation with acceptable migration in HDPE may fail in LLDPE at the same additive loading.

Specification and end-test framework in FDA 21 CFR 177.1520 and GB 4806.7-2016

21 CFR 177.1520 is the US olefin polymer regulation for PE and related polyolefins. It addresses polymer identity and permitted adjuvants, and it relies on extraction testing rather than a single overall migration value. The end-test conditions are selected according to food type and temperature. PE articles for aqueous, acidic, alcoholic, or fatty foods are tested with the corresponding food simulant; fatty-food applications may use n-heptane or food oil, while aqueous and acidic applications use water and dilute acid. The extractives limit is specific to the food-type classification and is not equivalent to the 10 mg/dm² EU limit. A change in food type, service temperature, additive formulation, or polymer grade can require new extraction data. In production, HDPE blow-moulded bottles for milk and LDPE films for dry foods do not have identical FDA testing obligations because the food simulant and exposure conditions differ.

GB 4806.7-2016 applies to finished plastic food-contact materials and articles. It requires that the resin meet GB 4806.6-2016 and that additives meet GB 9685-2016. The standard sets a total migration limit of 10 mg/dm² or 60 mg/kg for infant food contact, measured according to GB 31604.2. It also imposes a potassium permanganate consumption limit of 10 mg/kg under GB 31604.8 and a heavy metal limit expressed as lead of 1 mg/kg under GB 31604.9. Food simulants and test temperatures are selected under GB 31604.1. The potassium permanganate consumption and heavy metal tests reflect an additional purity and oxidative residue check not present in the same form in the EU framework. For PE, the total migration limit may be exceeded in fatty simulants when excessive slip agent or low-molecular-weight wax is present. Sensory testing is also required; PE films must not transfer odour or taste to food.

When melt temperature and regrind content alter the migration profile of PE food-contact articles

Thermal degradation is a key variable in food-grade PE production. Blown-film lines processing LDPE/LLDPE blends typically operate between 190 °C and 230 °C, but local shear heating can raise melt film temperature above the set-point. At temperatures above 230 °C, thermo-oxidative degradation of PE forms carbonyl-containing oligomers. On a three-layer blown-film line with a 65 mm barrier screw and 28:1 L/D, these low-molecular-weight oxidation products can accumulate in the melt film during extended runs. Injection moulding of HDPE closures at barrel set values above 250 °C increases the probability of shear-induced molecular weight reduction. The resulting extractables are not captured by resin melt flow rate or density certificates from the resin supplier. In-mould residence time, hot-runner temperature, and gate geometry all influence local thermal history and therefore the extractable fraction. Production batches with the same incoming resin can show migration differences if processing conditions are not controlled.

Regrind use concentrates thermal history. Clean PE scrap from the same food-contact article is commonly reintroduced in edge trim and start-up waste, but each pass through the extruder increases oxidative homologues. In EU practice, if recycled PE is used without a functional barrier, it must comply with EU 10/2011 as a plastic material; post-consumer recyclate needs additional authorisation and challenge-testing to demonstrate decontamination under relevant EU requirements. In China, GB 4806.7-2016 requires that food-contact plastic articles using recycled plastics meet the applicable national standards and are approved for intended contact. Published data for a universal safe regrind level in PE food packaging is limited. The acceptable level must be established by migration testing on the final article, with particular attention to the fatty simulant. Multilayer film can reduce migration from a contaminated core, but delamination, seal exposure, and edge diffusion reduce barrier efficiency. Overall migration tests on the finished pouch or tray should include seals, corners, and cut edges to avoid underestimating the available contact surface.