The wrapper around your food can be perfectly compostable and still pass unwanted chemicals into your meal.
Biodegradability is an end-of-life property. It is about what happens to the material in soil, water or a compost heap once you are done with it. That is an environmental question.
Migration is a food-safety property. It describes what moves out of the packaging and into the food during storage and use. These substances may include leftover raw materials, additives, or degradation products formed over time. Even though they may move in very small amounts, these chemicals can cross the barrier between the package and the food. Understanding migration is essential because it directly relates to consumer health and is a factor that is often overlooked when considering food safety.
You can see why the mix-up happens. Both sound “green.” Both feel reassuring. But knowing a wrapper will rot nicely in a field tells you nothing about what it does while holding hot food for some time.
The Migration Limit
In the European Union, the rules on plastic food-contact materials set an overall migration limit. No more than 10 milligrams of substances may pass into food per square decimetre of packaging surface (European Commission, 2011). Cross that line and the material is not considered safe for food, whatever else it is.
On top of that overall cap, individual substances of concern have their own tighter limits. Compliance has to be shown with a written declaration and a technical file behind it. This is the paperwork that answers “is it safe to eat from.” And it is completely separate from any compost certificate.
A compost certificate tells you the wrapper will leave the planet cleanly. It does not tell you whether it will leave your food alone or not.
Being plant-based or biodegradable does not mean a material is free of migration risk.
Every plastic, conventional or bio-based, can carry what scientists call non-intentionally added substances. These are impurities, leftover reaction bits, and breakdown products. Nobody put them in on purpose, but they can still migrate into food (Seref & Cufaoglu, 2025). Bioplastics have their own versions, so they need the same testing. The gentle-sounding name is not a free pass.
The flip side is just as interesting, and it cuts in favour of good bioplastics. One study found that coating a PVC film with biodegradable PLA actually reduced chemical migration. One common plasticiser dropped by roughly 50% (Seref & Cufaoglu, 2025). A well-made biomaterial can be a better barrier, not a worse one. The point is not that bioplastics are risky. It is that the answer comes from testing, never from the label.
What This Means When You Buy Packaging
Say a supplier leads with “compostable” and “eco-friendly,” then goes quiet when you ask about migration. They have answered the wrong question. And skipped the one that touches the customer’s health.
The order of questions should flip.
First, is this safe for my food, with migration data to prove it?
Second, is it also good for the planet at end of life?
A material that is compostable but untested for migration is not a sustainable choice. It is an unfinished one.
How TerraPHA Helps
TerraPHA Biotech is World’s first commercial biopolymer company, making PHA from naturally occurring, non-GMO microbes. PHA is genuinely biodegradable, which handles the end-of-life question honestly. But the reason it belongs in a piece about migration is that it is designed to answer both questions rather than hide behind one.
For a food brand, that is the distinction that matters. The right packaging partner does not wave a compost logo and hope you stop asking. It can speak to biodegradability and to migration, and back the second with the testing that food-contact rules actually require. Ask for both. A material worth using can answer both.
Frequently Asked Questions
What is migration testing, in plain terms?
It measures how much of the packaging moves into the food during real storage and use. There is an overall limit for the total, and tighter limits for specific substances of concern. Passing it is what lets a material be legally sold for food contact in the EU (European Commission, 2011).
If something is biodegradable, isn’t it automatically food-safe?
No. Biodegradability is about what happens to the wrapper after disposal. Migration is about what enters the food while it is packed. They are independent, and a compostable material still has to pass migration testing before it is safe for food.
Do bioplastics carry chemical migration risks too?
Yes. Like all plastics, bioplastics can contain non-intentionally added substances such as impurities and breakdown products that may migrate (Seref & Cufaoglu, 2025). That is why they need the same food-contact testing. Interestingly, some biomaterials can also reduce migration when used as a barrier layer.
What should I ask a packaging supplier first?
Ask for migration test results and a declaration of compliance for the exact material and use conditions, before you ask about composting. If they can only talk about biodegradability, they have answered the environmental question and skipped the safety one.
References
European Commission. (2011). Commission Regulation (EU) No 10/2011 on plastic materials and articles intended to come into contact with food. EUR-Lex. https://eur-lex.europa.eu/eli/reg/2011/10/oj
Seref, N., & Cufaoglu, G. (2025). Food packaging and chemical migration: A food safety perspective. Journal of Food Science, 90(5), e70265. https://doi.org/10.1111/1750-3841.70265
