NIAS in Food Packaging: The Risk Teams Underestimate

NIAS are substances present in a food contact material that weren't deliberately added for a technical purpose. They typically come from a handful of sources:

• Impurities in the starting materials, such as traces left over from manufacturing a monomer or additive

• Reaction by-products formed during polymerization or other chemical processes

• Breakdown products created when materials degrade, for example under heat, light or processing

• Contaminants that enter during production, handling or recycling

Some NIAS are well known, such as oligomers (short chains of the polymer itself) or breakdown products of common antioxidants. Others are completely unidentified until someone looks for them.

Food contact rules are largely built around known substances. Approved lists, specific limits and test methods all assume you know what you're dealing with. NIAS break that assumption.

A material can contain only approved ingredients, pass every test for the substances on the list, and still release other substances into food that nobody evaluated. Regulators in several markets expect companies to consider this, and in the EU, for example, the general safety requirement for food contact materials applies to everything that can transfer to food, not just listed substances.

That's why a packaging structure can look fully compliant on paper and still carry an unaddressed risk.

They're not on any list. There's no approved list of NIAS and no ready-made limit for each one. You can't simply look up the answer.

You often don't know what they are. Unlike an additive you selected, NIAS may be unidentified, which makes them hard to test for and harder to assess.

Standard testing doesn't find them. Routine migration tests usually look for specific, known substances. They won't reveal unexpected ones unless someone deliberately looks.

Supplier information is limited. Suppliers protect their formulations, and they may not know every impurity or breakdown product either.

Responsibility is spread out. NIAS can arise at any stage of a long supply chain, so everyone assumes someone else has dealt with them.

Nobody knows what "enough" looks like. There's no single checklist that says when you've done enough, which makes it easy to either skip the question or get lost in it.

Documents can create false comfort. A supplier declaration may confirm compliance with listed substances while saying little or nothing about NIAS.

Multilayer and multi-material packaging concentrates all these problems. A single structure can include several polymers, adhesives, coatings and printing inks, each made by a different supplier, each with its own impurities and potential breakdown products.

Some familiar examples:

• Adhesives between layers can release residues or form by-products during curing and storage. Certain adhesive chemistries are known to generate particular substances that need attention.

• Printing inks and coatings may contain components that break down or react, especially when exposed to light or heat during processing.

• Heat during lamination and forming can create degradation products that weren't present in the raw materials.

• Layer interactions can mean that what's in one layer ends up elsewhere in the structure.

Whether an inner layer is separated from the food by an effective barrier is a technical judgment, and it needs evidence for the specific structure and use. It's one of the central questions in multilayer packaging compliance.

You can't test for every possible substance, so the aim is a reasoned, proportionate approach. Here's a workable outline.

1. Map the structure and the supply chain. List every layer and component: polymers, adhesives, coatings, inks and additives, plus who supplies each. You can't assess what you haven't identified.

2. Think about likely sources of NIAS. Consider the chemistry and the process. Which materials commonly contain oligomers? Where are adhesives cured? Where does heat or light act on the material? Which components are most likely to degrade?

3. Ask suppliers specific questions. Go beyond "is it compliant?" Ask whether they've considered impurities, by-products and breakdown products, what they know about them, whether any assessment has been done, and whether they'll tell you about process or formulation changes.

4. Judge the level of risk. Not every structure carries the same concern. Consider the type of food, the contact conditions, the layers involved and the intended shelf life, and focus effort where the risk is highest.

5. Use testing where it's justified. For higher-risk structures, screening methods can look more broadly for substances that migrate, beyond the known list. Interpreting the results takes expertise, and it's worth involving someone experienced in the method.

6. Assess what you find. Identified substances need a safety assessment appropriate to their level and toxicological profile. Scientific approaches used for this include screening tools that compare estimated exposure to levels of low concern. This is expert work, so involve a qualified toxicologist or regulatory specialist.

7. Document your reasoning. Record what you considered, what you tested, what you concluded and why. If someone asks later, a clear, reasoned file is far better than silence.

8. Control change. A change in a supplier, formulation, adhesive or process can introduce new NIAS. Make any such change trigger a compliance review.

Assuming compliance with the list is the whole picture. The list covers known, intentionally used substances only.

Relying on a single supplier statement. In a multilayer structure, no single supplier sees the whole thing.

Ignoring adhesives and inks. They're often treated as minor but can contribute significantly.

Treating NIAS as purely a testing problem. A good assessment starts with understanding the chemistry and the process.

Testing without expert interpretation. Broad screening produces data that needs skilled evaluation.

Not revisiting after changes. New suppliers or processes can change the picture.

Giving up because there's no perfect answer. A reasoned, documented, proportionate approach is the goal.

NIAS don't have to be intimidating. They need a structured way of thinking: know your structure, ask the right questions, apply effort where the risk is highest and keep a clear record. Teams that build this habit find fewer unpleasant surprises in audits and customer reviews.

Learn how regulators and companies approach complex structures in ourIntroduction to Global Regulations for Multilayers and Multi-Materials course, which covers how these systems are designed, how migration is evaluated and how major markets regulate them.