Standards and Precautions for Testing Chemical Migration of Food Packaging Materials in Various Countries

Food packaging materials refer to products made of paper, bamboo, wood, metal, enamel, ceramics, plastics, rubber, natural fibers, chemical fibers, glass, etc., used for packaging or holding food or food additives, as well as coatings that come into direct contact with food or food additives. Because food packaging materials come into direct contact with food, Article 33 of the Food Safety Law stipulates: "(vii) Food intended for direct consumption shall use non-toxic and clean packaging materials, tableware, drinking utensils, and containers." Therefore, it is essential to ensure that the packaging materials themselves are safe, non-toxic, and do not generate volatile substances. Furthermore, during the packaging process, no substances or chemical components that react chemically with food components should be generated.

I. Risks of Food Packaging Materials

Due to the complexity of the composition of packaging materials, substances from food packaging materials may leach into the food, either through migration or accidental extraction. This chemical migration from food packaging can negatively impact the food. This manifests primarily in two aspects:

Firstly, harmful substances from synthetic packaging materials migrate into food, causing harm to human health.

Secondly, these migrated substances may deteriorate the sensory properties of food, such as producing off-flavors, discoloration, and stains.

Modern food packaging utilizes a large number of chemically synthesized substances, which can be broadly categorized into two types: known components and unknown components. These substances mainly include:

monomers and other synthetic materials, catalysts, solvents and suspending media, and packaging material additives (including antioxidants, antistatic agents, antifogging agents, plasticizers, heat stabilizers, nucleating agents, and dyes and pigments).

II. Standard Requirements for Hazardous Substances in Food Packaging Materials in Various Countries

To effectively control harmful substances in food packaging materials, many countries have established standards for limiting harmful substances in food packaging materials.

The EU Food Contact Materials Regulation comprises three levels: framework regulations, specific directives, and individual directives. Framework regulations stipulate the general principles for the management of food contact materials; specific directives specify a series of requirements for each category of materials listed in the framework regulations; and individual directives are specific provisions for individual harmful substances.

In the United States, the regulation of food packaging materials is primarily governed by the Commonwealth Federal Regulations (CFR). Part 21 of CFR mainly regulates food and drug administration, with Sections 170-186 specifically addressing the requirements for food packaging materials. 21 CFR 174 (Food Additives for Indirect Use – General) sets forth general requirements for food packaging materials and legal limits for substances that come into contact with food. The general requirements for food contact materials include: materials must be manufactured according to GMP requirements; materials must use substances approved under 21 CFR 170-189; and new materials must be reviewed and approved by the FDA before entering the market.

21 CFR 170-189 provides very detailed control requirements for food contact materials. In addition to the general requirements, specific regulations apply to paper, wood, plastics, coatings, rubber, adhesives, etc., as shown in Figure 2. The relevant requirements for different materials include not only the monomers, additives, and auxiliaries permitted for their production, but also requirements for their purity and dosage. There are also testing requirements for the leaching of finished products and the leaching of specific substances. Some plastic materials also have requirements for physical properties (such as density, melting point, molecular weight, and solubility).

Since the implementation of the Food Safety Law, my country's food packaging material safety standard system is gradually being built and improved.

GB 31603.1-2015, "General Rules for Migration Testing of Food Contact Materials and Articles," specifies the selection of test conditions for food simulants, special migration, and total migration. The food contact material additive standard (GB 9685-XXXX) is more reasonable than GB 9685-2008. The main change is the adjustment of the structure of the appendix chemical substance list (detailing additives in plastics, coatings, rubber, inks, adhesives, paper, and silicone rubber), classifying the additive list and their usage requirements according to their scope of use, and expanding the number of additive varieties from 959 to 1297. 

III. General Detection Methods for Chemical Migrating Substances in Food Packaging Materials

Regardless of the type of packaging material, once it is used for food packaging, it needs to undergo hygiene testing. The testing method generally uses food models. It roughly consists of the following steps:

(1) Selecting a typical sample;

(2) Selecting an appropriate food model;

(3) Selecting suitable conditions, mainly choosing appropriate temperature and contact time;

(4) Selecting appropriate exposure;

(5) Monitoring the exposure level;

(6) Analyzing the safety of the packaging.

IV. Precautions for Detecting Chemical Migrating Substances in Food Packaging Materials

(1) Sample Selection and Food Model Selection

Directly detecting and analyzing migrating substances in food is intuitive, but expensive and has relatively low sensitivity. Generally, food models are used for experiments. This involves using special solvents as food simulants to replace food in order to address the difficulty of separating migrating substances from food.

(2) Determining Monitoring Conditions

After determining a suitable food simulant, to ensure the safety of the packaging material and to accurately reflect the reaction, the monitoring is generally conducted under conditions at the maximum migration limit of the migrating substances.