The German Federal Institute for Risk Assessment (BfR) has updated its guidance on the risk assessment of non-intentionally added substances (NIAS) in food contact materials (FCMs). The guidance document, published on September 10, 2026, was developed with expert advice from the BfR Commission for Consumer Products. The authors note that “the document is not a rigidly prescribed procedure but a guideline that outlines the BfR’s general expectations and scientific approach for the assessment of NIAS.”
What are NIAS?
NIAS are chemicals that are present in FCMs but have not been added for a technical reason during the production process. They can arise from impurities in starting materials, reaction by-products, degradation products, or other chemical transformations occurring during manufacturing and use. While some NIAS may be predicted based on the knowledge of chemical processes, manufacturer’s experience, and conditions of use, other NIAS may remain completely unknown. Assessing NIAS therefore remains one of the most challenging aspects of ensuring the chemical safety of FCMs.
Tiered framework for NIAS risk assessment
For the purpose of risk assessing NIAS in FCMs, BfR proposes a tiered framework in which the amount of a substance migrating into food determines the level of toxicological information required.
The BfR document emphasizes that manufacturers should first make reasonable efforts to characterize NIAS and specifies a minimum analytical approach to do so. According to the guidance, both gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) should be used to screen for NIAS where relevant.
Where possible, substances should be identified, exposure estimated through migration testing or modeling, and toxicological information gathered from existing studies, read-across approaches, or computational methods (FPF reported).
For substances with a migration level of less than 0.15 µg/kg food, no toxicological data are generally required. The justification given for this is that at this migration level “[e]ven in the worst-case assumption that the respective substance is a potent mutagenic carcinogen (which is not the case for the vast majority of substances), the risk for an additional tumour disease is estimated to be one in one million persons.” However, this threshold has previously been criticized by scientists as being based on an outdated understanding of dose-response relationships (FPF reported).
For migration levels between 0.15 and 10 µg/kg food, limited toxicological information is required, while 10-50 µg/kg food triggers additional assessment on a case-by-case basis, including consideration of genotoxicity testing for unidentified substances. Migration levels above 50 µg/kg food generally require more extensive toxicological information.
The guidance also considers molecular weight, noting that substances with a molecular mass above 1,000 Da are generally assumed to have limited gastrointestinal absorption. However, this assumption does not necessarily apply to oligomers, which may be absorbed or degrade into smaller, absorbable substances and therefore should be considered in the assessment (FPF reported).
Accounting for unidentified substances
Notably, the guidance acknowledges that complete identification of all NIAS may not always be achievable despite extensive analytical efforts. Therefore, rather than requiring full structural characterization in every case, the framework allows assessors to combine exposure estimates with other lines of evidence, including expert judgment and toxicological testing strategies such as using bioassays.
For unidentified substances migrating at higher levels, the guidance highlights the use of genotoxicity testing, including the Ames test and in vitro micronucleus assays. The document also points to the increasing role of new approach methodologies (NAMs) in supporting safety evaluations (FPF reported).
Looking beyond chemical identification and genotoxicity testing
The guidance’s acknowledgement that chemical identification issues will remain may increase interest in complementary biological testing strategies. Rather than focusing exclusively on identifying individual compounds, researchers have proposed testing the overall migrate or extract from a food contact material using a selection of bioassays (FPF reported). Such approaches assess the biological activity of the mixture as a whole, including unidentified substances that may not be captured through conventional chemical analyses.
To address this, the BfR guidance primarily discusses genotoxicity testing using appropriate bioassays. However, food contact materials have been reported to contain chemicals associated with endocrine activity, metabolic disruption, developmental toxicity, neurotoxicity, and immune-related effects, not only genotoxicity-induced cancer. Therefore, many scientists argue that focusing solely on genotoxicity may overlook other health-relevant effects.
To fill this gap, research is underway to develop reliable testing procedures that can be recommended to regulators for a broader range of health effects. Recently, a selection of such bioassays was identified that could expand the range of biological endpoints beyond genotoxicity that are assessed in complex chemical mixtures (FPF reported).
Reference
German Federal Institute for Risk Assessment (September 10, 2026). “BfR Guideline for risk assessment of non-intentionally added substances (NIAS) in the area of food contact materials.” German Federal Institute for Risk Assessment. DOI: 10.17590/20260910-084007-0
