Meaning
Detailed concentration values established by safety authorities restrict the movement of chemical constituents from packaging materials into various types of consumable food. These specific migration limits apply to individual chemicals such as monomers, plasticizers and antioxidants that are used in the manufacturing of plastic parts. Each value is based on a toxicological assessment of the substance to determine the maximum amount that can be safely ingested.
The limits are usually expressed in milligrams of the chemical per kilogram of food. Compliance with these rules is necessary to ensure that packaging does not change the composition of the food or harm human health. This requirement is a central part of food contact legislation in many countries.
Hazard Management
The primary purpose of setting specific migration limits is to control the risk associated with chemical exposure from packaging. Some substances are allowed to migrate in relatively large amounts because they have low toxicity, while others are restricted to trace levels. For chemicals that are not fully assessed, a default limit might be applied to ensure a high level of safety.
These values are updated regularly as new scientific evidence becomes available. Moulders must be aware of the specific additives in their resin and whether they are subject to any restrictions. If a resin contains a substance with a very low limit, the processing conditions must be carefully controlled to prevent excessive migration.
This is particularly important for parts that will be used with fatty foods, which often extract chemicals more easily.
Testing Procedure
Demonstrating compliance with specific migration limits involves laboratory analysis using food simulants under controlled temperature and time. The simulants are chosen to mimic the behavior of different food groups, such as water for aqueous foods and vegetable oil for fats. After the exposure period, the simulant is analyzed to detect the presence of the restricted substances.
This analysis requires high precision equipment that can measure chemicals at the parts per million or even parts per billion level. If the results show that the migration is above the legal threshold, the manufacturer must find a way to reduce it. This might involve changing the material formulation or reducing the surface area to volume ratio of the packaging.
The testing results are a key part of the technical documentation for the product.
Compliance Record
Manufacturers are required to provide a declaration of compliance that confirms their products meet all relevant specific migration limits. This document must be passed down the supply chain to the final brand owner. It provides the necessary assurance that the packaging is safe for its intended use.
Recyclers using post consumer material also face challenges in meeting these limits, as they must ensure that any contaminants from the waste stream are also below the thresholds. Regular audits and batch testing are often used to verify that the production process remains within the legal boundaries. Failure to maintain these records can lead to market rejections and legal penalties.
The management of these limits is a continuous duty for all participants in the plastic industry.
