Think about the last time you heated leftovers in a plastic container, grabbed a fast food wrapper, or opened a can of tomatoes that had been sitting in the pantry for months. In each of those moments, the packaging was in contact with your food — and what it was made from was affecting what you were eating.
Food packaging is in direct contact with what we eat from the moment it’s produced to the moment it’s consumed — sometimes for days, sometimes for months. The container it comes in tends not to factor into how food gets evaluated. But packaging isn’t passive. It interacts with the food inside it, and under the right conditions — heat, acidity, fat content, time — that interaction transfers compounds from the packaging into the food itself.
None of that shows up on any ingredient list. Here’s what’s worth knowing.
How Packaging Affects Food — The Basic Mechanism
The process by which compounds move from packaging into food is called chemical migration. It happens when substances in the packaging material — whether from the material itself, from additives used during manufacturing, or from coatings applied to the surface — cross the boundary between the packaging and the food it contains.
Migration isn’t random. Research by Zhang et al. published in 2025 — one of the most comprehensive recent reviews of chemical migration from food packaging — identified the conditions that drive it most consistently: temperature, contact time, the fat content of the food, and its acidity. Heat is the most significant accelerator — compounds that migrate slowly at room temperature migrate significantly faster when packaging is warmed. This is why heating food in a plastic container is a more direct concern than storing it in one. Fat dissolves certain packaging compounds more readily than water, which makes fatty foods — cheese, meat, oils — more vulnerable to migration than low-fat ones. Acidic foods — tomatoes, citrus, vinegar-based products — interact with certain packaging materials in ways that increase migration rates, particularly from metal can linings.
Contact time matters too. A food product stored in packaging for weeks or months has a meaningfully different migration profile than one purchased and consumed within days. The compounds involved aren’t always obvious from the packaging’s appearance — a container that looks intact and undamaged can still be migrating compounds into its contents throughout its shelf life.
Plastic Packaging
Plastic is the most widely used food packaging material globally, and it’s also the most chemically complex from a migration standpoint. Plastic isn’t a single material — it’s a broad category covering dozens of different polymer types, each with its own chemical composition and migration profile.
BPA — bisphenol A — became one of the most recognized packaging concerns after research established it as an endocrine-disrupting compound, meaning it interferes with the body’s hormone system. As covered in What Are Endocrine Disruptors, BPA mimics estrogen — binding to estrogen receptors and triggering hormonal responses at concentrations far below those traditionally considered toxic. The widespread shift to BPA-free plastic addressed one specific compound. As de Paula and Alves documented in their 2024 review of food packaging and endocrine disruptors, the replacement compounds — primarily BPS and BPF — have shown similar hormonal activity in laboratory studies to the compound they replaced. A BPA-free label addresses a single ingredient while leaving the broader question of plastic chemical migration largely unchanged.
Phthalates — a class of chemicals used to make plastic more flexible — are another consistent migration concern in food packaging. They’re found in PVC plastic used in some food wraps and packaging films, and they’ve been associated with endocrine disruption in a range of studies. Like BPA, phthalates migrate into food at higher rates under conditions of heat, fat, and acidity.
Lacourt et al.’s 2024 review of emerging food packaging alternatives and their chemical safety profiles noted that newer packaging materials — including bio-based and compostable plastics — are increasingly marketed as safer alternatives to conventional plastic, but that their migration profiles are less well studied than established materials. A packaging material being plant-derived or compostable doesn’t automatically mean it migrates fewer or less concerning compounds into food — it means the research base is smaller and the safety profile less established.
Can Linings
Metal cans are lined on their interior to prevent the food inside from coming into direct contact with the metal — a necessary step for preventing corrosion and preserving food quality. The lining is where the packaging concern lies.
Most conventional can linings have historically used epoxy resins containing BPA. The food inside a can is in contact with that lining from the moment it’s sealed — sometimes for years before being opened. As de Paula and Alves documented, BPA migration from can linings into food has been consistently measured across a range of canned products, with acidic foods like tomatoes showing the highest migration rates. A single serving of canned tomatoes has been found to contain measurable BPA from the lining, reflecting the combination of acidity and extended contact time.
Many manufacturers have transitioned to BPA-free can linings in response to consumer pressure and regulatory movement — but as with plastic packaging, the replacement compounds are not uniformly better characterized. Some BPA-free linings use BPS or other bisphenol alternatives with similar hormonal activity profiles. Others use vinyl-based linings or acrylic coatings whose migration profiles are less studied. The “BPA-free” designation on a can tells you one specific compound was removed. It doesn’t tell you what replaced it or whether that replacement has been independently evaluated for safety.
For high-use canned goods — tomatoes, beans, soups — prioritizing glass-jarred or Tetra Pak alternatives reduces the can lining exposure most directly. Glass doesn’t migrate compounds into food under normal storage conditions. Tetra Pak cartons use a multi-layer construction that includes a thin plastic layer, but their migration profile under normal storage conditions is generally considered lower than metal cans for most food types.
Food-Contact Coatings and PFAS
PFAS — per- and polyfluoroalkyl substances, the same class of forever chemicals discussed in Is Non-Stick Cookware Safe? PTFE and PFAS Explained — are used extensively in grease-resistant food packaging. Fast food wrappers, microwave popcorn bags, pizza boxes, sandwich wrappers, and some takeout containers use PFAS-containing coatings that prevent oil and grease from soaking through the packaging material.
The problem is that PFAS migrate from these coatings into the food they’re in contact with — particularly into fatty foods, where fat acts as a solvent that draws PFAS compounds out of the coating. Zhang et al.’s 2025 review identified PFAS migration from food-contact materials as one of the more significant and actively researched areas of food packaging safety, noting that the combination of fat content, heat, and contact time in fast food and microwave packaging creates conditions that accelerate migration beyond what occurs in lower-fat, lower-temperature applications.
PFAS from food packaging represent a dietary exposure route that operates independently of other PFAS sources — drinking water, cookware, textiles — and contributes to the cumulative body burden of these compounds. Because PFAS don’t break down in the body, each exposure source adds to a total that accumulates over time rather than clearing between exposures.
Regulatory movement on PFAS in food packaging has accelerated in recent years. Several states including California have passed legislation restricting PFAS in food packaging, and some fast food chains and manufacturers have committed to phasing them out. The transition is ongoing and uneven — checking whether specific brands or packaging types have moved away from PFAS is worth doing for products used frequently.
What Doesn’t Appear on Any Label
Packaging materials aren’t required to be disclosed on food labels in the U.S. The ingredient list tells you what was intentionally added to the food during production. It doesn’t tell you what the packaging has contributed to the food’s composition during storage and distribution.
This is what researchers refer to as indirect food additives — compounds that end up in food not because they were added intentionally but because they migrated from packaging, processing equipment, or other food-contact materials. The FDA regulates indirect food additives through a separate framework from direct food additives, but the regulatory pathway for approving food-contact materials has historically been less rigorous than for intentional food ingredients — and many compounds used in food packaging were approved under older standards that didn’t account for endocrine disruption or cumulative exposure.
Lacourt et al. noted that the regulatory frameworks governing food packaging safety in the U.S. and EU are still catching up to the science on migration — particularly for newer materials and for the cumulative effects of multiple packaging-derived compounds. The gap between what the label discloses and what the food actually contains is one that label reading alone can’t close. It’s where certifications, sourcing decisions, and packaging material choices do work that the ingredient list can’t.
California’s Proposition 65 requires businesses to warn consumers when their products contain chemicals known to cause cancer, birth defects, or reproductive harm. When you see a Prop 65 warning on a food product or its packaging, it means a listed chemical of concern is present — and it’s worth paying attention to. The California Office of Environmental Health Hazard Assessment maintains a public list of all covered chemicals, which is a useful reference for understanding what a warning on a specific product is flagging.
Practical Steps
Reducing food packaging exposure doesn’t require eliminating packaged food entirely. It requires knowing which packaging types and conditions carry the most significant migration risk and making adjustments where they’re most practical.
Glass is the most straightforward alternative for food storage — it doesn’t migrate compounds into food under normal conditions, handles heat and acidity without concern, and is reusable. Prioritizing glass-jarred alternatives to canned goods for high-acid, high-use items — tomatoes, sauces, pickled vegetables — addresses one of the most consistent migration sources in a typical diet. Borosilicate glass, as covered in Hidden Toxin Exposure in the Kitchen, is the more thermally stable option and worth seeking out specifically for food storage containers that will be used with heat.
Avoiding heat with plastic is one of the most directly actionable steps available. The migration rate increase associated with heating plastic is significant enough that simply transferring food to a glass or stainless steel container before microwaving or reheating addresses the highest-risk moment in plastic packaging’s contact with food. Room-temperature storage in plastic presents less immediate concern than heated contact.
For takeout and fast food packaging — where PFAS-containing grease-resistant coatings are most common — reducing frequency of use and transferring food out of the packaging as soon as possible reduces contact time and heat-driven migration. Asking whether a specific chain or brand has committed to PFAS-free packaging is worth doing for regularly used sources.
Stainless steel and glass food storage containers handle most food storage needs without migration concerns. For on-the-go use, stainless steel containers and bottles don’t carry the BPA and phthalate concerns associated with plastic alternatives and are durable enough for long-term use.
Beyond the Ingredient List
Food packaging is a category where label reading reaches its limit. The ingredient list reflects what was intentionally added to the food. What the packaging contributes — BPA and its replacements from plastic and can linings, PFAS from grease-resistant coatings, phthalates from flexible packaging — doesn’t appear anywhere on that list.
Knowing what the most common packaging materials are, which conditions accelerate migration, and where the highest-risk interactions occur gives you a more complete picture of what’s in your food than the label alone provides. It’s one more layer of awareness that compounds over time — and one that the food industry’s labeling framework doesn’t currently require anyone to give you.
The references used in this article are a starting point — we encourage you to read further and draw your own conclusions.
Ready to keep going? Browse our Mindful Eating articles to build a clearer picture of what’s in your food and how to evaluate it.
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