Chemical Contamination from Food Contact Materials: Migration Incident
Background
Northfield Cheese Company is a fictional artisan cheesemaker producing aged cheddar and gouda-style cheeses for regional retailers. Its packaging line wraps individual 400-gram blocks in plastic film before boxing — a step handled for years by the same supplier with the same PVC-based cling film.
In early spring, the purchasing department switched to a lower-cost film from a new supplier to reduce packaging expenses. The new film looked and performed identically on the line: same clarity, same cling, same seal strength. No change notification went to quality assurance, and no food-contact documentation was requested from the new supplier.
Three months later, a retail customer’s routine surveillance testing flagged the problem. Gas chromatography–mass spectrometry (GC-MS) analysis of the cheese found di(2-ethylhexyl) phthalate (DEHP) at 3.2 milligrams per kilogram — more than double the European Union specific migration limit (SML) of 1.5 mg/kg for DEHP in food. Follow-up testing of retained packages from six production lots showed DEHP ranging from 1.8 to 3.9 mg/kg, with the highest levels in the oldest stock.
Investigation
DEHP is a plasticizer added to polyvinyl chloride (PVC) to make it flexible. It is not chemically bound to the polymer, so it migrates freely — especially into fatty foods, where its fat solubility drives transfer from packaging into product. Aged cheddar at 33 percent fat is close to a worst case for this migration pathway.
Investigators compared the old and new films. The original supplier’s film was a polyethylene-based product containing no phthalate plasticizers, supplied with a declaration of compliance confirming suitability for fatty foods under EU Regulation 10/2011 on plastic food-contact materials. The replacement film was PVC plasticized with approximately 28 percent DEHP by weight — a formulation intended for wrapping fresh produce and other low-fat foods, where migration stays within limits because there is little fat to draw the plasticizer out.
Migration testing confirmed the mechanism. Laboratory analysis using olive oil as a fatty-food simulant showed the new film releasing DEHP at rates that would exceed the 1.5 mg/kg SML within days of contact at refrigerated storage temperatures. Time-series testing of actual cheese demonstrated the expected pattern: DEHP levels rose steadily with storage time, which explained why the oldest lots tested highest.
The paper trail revealed the administrative failure. Purchasing had requested only price and delivery terms. Nobody asked for a declaration of compliance, a composition statement, or migration test data. The supplier’s technical datasheet — which clearly stated “suitable for non-fatty foods” — sat unopened in an email attachment for three months.
Root Cause
Chemical migration from food-contact materials is governed by a simple principle: substances move from packaging into food when chemistry favors it, and fat content, contact time, temperature, and the packaging formulation together determine how much moves. Every element here favored migration — a heavily plasticized film, a high-fat cheese, and weeks of direct contact during distribution and retail display.
The root cause was not the film itself; PVC cling film has legitimate food uses. It was the substitution of a material qualified for one application into a different, more demanding one without any safety assessment. Packaging suitability is not transferable between product types — a film safe for cucumbers can be unsafe for cheddar.
Behind that sat a broken change-control process. Purchasing authority to switch suppliers existed without a parallel requirement for quality approval of food-contact materials. The company’s supplier approval program covered ingredient suppliers rigorously but treated packaging as a commercial rather than a food-safety decision.
Corrective Actions
Northfield recalled all lots wrapped in the PVC film — roughly 18,000 units — and reverted immediately to the original polyethylene film while qualifying alternatives:
A formal packaging change-control procedure now requires quality assurance sign-off before any food-contact material is introduced or substituted. Every such material must arrive with a declaration of compliance referencing the applicable regulation, a composition statement identifying plasticizers and additives, and migration test data — or the company commissions its own testing before approval.
The supplier approval program was extended to all packaging suppliers with the same rigor applied to ingredients: questionnaires, documentation review, and periodic re-verification. Purchasing staff received training on why food-contact materials are a food-safety matter, and the “suitable for non-fatty foods” type of limitation is now a mandatory review item on every packaging specification sheet.
As verification, the company instituted annual migration screening on finished packaged products for each packaging format, using accredited laboratory GC-MS analysis. The first round confirmed the replacement film’s DEHP migration at non-detectable levels.
Lessons Learned
Packaging is an ingredient. Anything touching food for weeks can become part of the food. Treating packaging procurement as purely commercial — price and performance — misses the chemical reality of migration.
Suitability does not transfer. A material’s safety approval is tied to specific conditions of use: food type, contact time, temperature. Changing any of those conditions voids the assumption, and fatty foods are the sternest test for plasticizer migration.
Documentation is the control. Declarations of compliance, composition statements, and migration data exist precisely to prevent this kind of substitution error. Requesting them takes days; a recall takes months and costs customers’ trust.
Time amplifies migration. The oldest lots carried the highest DEHP levels — a reminder that shelf-life studies for packaged foods should consider chemical migration alongside microbial and sensory endpoints, especially for fatty products in plastic packaging.
