GB 31604.1-2023National food safety standard - General rules for migration test of food contact materials and products (English PDF)

Foreword

This document was issued on 6 September 2023 by the State Administration for Market Regulation; Standardization Administration of the PRC and takes effect on 6 September 2024.

It is a GB standard without the /T suffix: compliance is mandatory in China.

1 Scope

GB 31604.1-2023 is the general rule that governs how migration from a food contact material or article is tested: what a migration test is, the basic requirements for running one, how a food simulant is chosen for the food the article is meant to hold, how the time and temperature of the test are selected, screening methods for overall migration, chemical solvent substitution for foods containing oil, correction of the result, and which of several results is taken as the answer. An annex maps food categories to simulants. The rules sit in one document because a migration figure has no meaning without them. The same plastic cup releases quite different amounts into water, into an acidic simulant and into ethanol, and different amounts again cold and at hot-fill temperature, so two laboratories can test the same article honestly and report incomparable numbers. The correction rules matter for the same reason: the ratio of contact area to food volume in a test cell is rarely the ratio in real use. For articles meant to be reused, the third of three successive tests is taken, because release falls with each contact and the first would overstate what a consumer is exposed to over the article's life. Testing laboratories, packaging and tableware manufacturers, importers and regulators use it, and it is mandatory.

This document specifies the terms and definitions, basic requirements, selection of food

simulants, selection of migration testing conditions, screening methods, chemical

solvent substitution test, migration testing result correction and migration testing result

selection of various food contact materials and products.

2 Terms and definitions

2.1 Migration testing

Migration testing refers to a test conducted under specified conditions to determine the

amount of migration of components of food contact materials and products into test

medium such as food or food simulants in contact with them. Migration testing includes

specific migration testing, total migration testing and chemical solvent substitution test.

2.2 Food simulant

Food simulant is a test medium used to simulate food for migration testing. It can

closely reflect the migration of components in food contact materials and products into

the food in contact with them, and has the typical common characteristics of certain

types of food.

2.3 Screening method

It is a method that uses the amount used, total migration amount or residue amount to

screen for specific migration (total) amount, so as to verify the compliance of a specific

migration (total) amount of a certain (category) substance in food contact materials and

products.

2.4 Chemical solvent substitution test

A migration testing conducted under specified conditions using chemical solvents to

replace oily food simulants.

2.5 Reusable food contact materials and products

Food contact materials and products that have been or are expected to be used multiple

times and come into repeated contact with food.

3 Basic requirements

3.1 To measure the total migration amount of food contact materials and products, food

simulants shall be selected and migration testing shall be conducted in accordance with

the provisions of this Standard.

3.2 Regarding the determination of the specific migration (total) amount of food contact

materials and products, for materials and products that have been in contact with food,

the food in contact with them shall be directly tested, or materials and products that

have not been in contact with food shall be selected to use food simulants for migration

testing. For materials and products that have not come into contact with food, food or

food simulants shall be selected for testing.

3.3 Food simulants and migration testing conditions shall reflect actual use situations

as closely as possible. When food contact materials and products have clear intended

use conditions, the most stringent test conditions (the conditions that result in the

highest migration amount) shall be selected based on the expected use conditions. When

the most severe test conditions cannot be determined, all conditions corresponding to

the actual usage conditions shall be selected for testing. When there are no clear

intended use conditions for food contact materials and products, the most stringent test

conditions supported by scientific evidence shall be selected.

3.4 The migration testing shall not cause the test sample to undergo changes in physical

properties or other changes (such as deformation, melting, etc.) that would not occur

under normal use conditions. If the above changes occur during the migration testing,

test conditions that are no lower than the actual contact conditions or other food

simulants with scientific evidence shall be selected for the migration testing.

3.5 For migration testing, the final product (or sheet or specimen) shall be selected for

migration testing. For food contact materials (such as resin or granules, coatings, inks,

adhesives, etc.) that are significantly different from actual molded products, the final

product (or sheet, specimen) shall be made into a migration testing according to the

actual processing conditions. The specific requirements of the final product (or sheet or

specimen) shall comply with the provisions of GB 5009.156 and other national food

safety standards.

3.6 When conducting migration testing on multi-material food contact materials and

products, the migration testing can be conducted on the entire final product or on each

material separately.

3.6.1 When conducting migration testing on composite materials and finished products,

and coated finished products as a whole, the selection of food simulants and migration

testing conditions shall be carried out in accordance with the provisions of the national

food safety standards for materials in direct contact with food layers. For items to be

tested that only come from non-direct food contact layers, the selection of food

simulants and migration testing conditions can be carried out in accordance with the

provisions of the national food safety standards for the materials of this layer. When

conducting migration testing on combined materials and finished products as a whole,

the most stringent migration testing conditions shall be selected according to the

product instructions or the use conditions of all parts that may come into contact with

food.

3.6.2 When conducting migration testing on each material of multi-material food

contact materials and products, the migration testing shall be conducted separately in

accordance with the provisions of the national food safety standards for the

corresponding materials.

3.7 If national food safety standards have special provisions for migration testing, those

provisions shall be followed.

4 Selection of food simulants

4.1 General requirements for food simulant selection

4.1.1 When food contact materials and products are expected to come into contact with

a certain type of food (for example, acidic food), the corresponding food simulant shall

be selected according to the type of food expected to come into contact for specific

migration testing and total migration testing.

4.1.2 The selection of food simulants shall comply with the provisions of Annex A. For

foods not listed in Annex A, the selection of food simulants shall comply with the

requirements in Table 1.

NOTE. The food categories specified in Table 1 and Annex A are only applicable to this Standard.

4.1.3 When a variety of food simulants need to be selected for migration testing based

on expected use conditions, if there is scientific evidence to prove that a certain food

simulant can simulate the most severe migration conditions, other food simulants may

not be selected for migration testing.

4.1.4 When conducting migration testing on materials and products that come into

contact with dry food, the corresponding food shall be selected for testing. When testing

food is not feasible, at least one food simulant in Table 1 can be selected for migration

testing.

4.2 Selection of food simulants for total migration testing when expected exposure

to multiple food categories

When contact with multiple types of food (e.g., all food categories) is expected, the

selection of food simulants for the total migration testing shall be in accordance with

Table 2.For food categories that cannot be covered in Table 2, the selection of food

simulants shall comply with the provisions of Table 1.

5 Selection of migration testing conditions

5.1 Specific migration testing conditions

5.1.1 The selection of migration testing conditions (time and temperature) shall comply

with the provisions of Table 3 and Table 4.

5.1.2 When food contact materials and products continuously experience two or more

use conditions, the migration testing time and temperature in Table 3 and Table 4 shall

be selected sequentially according to the use conditions. Use the same specimen for the

migration testing.

5.1.3 For the migration testing of food contact materials and products heated by

microwave ovens, 130°C and 15 min shall be selected for food simulants containing oil.

For water-based foods and acidic food simulants, 100 degrees C and 15 min shall be selected.

For ethanol-containing food simulants, the reflux temperature and 15 min shall be

selected.

5.1.4 When stored at room temperature or below room temperature for more than 30 d,

the temperature acceleration test can be used to conduct a migration testing. The

selection of temperature acceleration test conditions shall comply with the provisions

of Table 5.

5.2 Total migration testing conditions

5.2.1 The total migration testing conditions shall comply with the requirements in Table

6.

5.2.2 When food contact materials and products continuously experience two or more

use conditions, the total migration testing conditions in Table 6 shall be selected

sequentially according to the use conditions. Use the same specimen for the migration

testing.

5.2.3 For materials and products that are not suitable for the total migration testing

conditions specified in 5.2.1, the test conditions shall be selected according to Table 3

and Table 4.

6 Screening methods

6.1 Total migration amount screening

For the specific migration (total) amount of a certain (type) of non-volatile substances

in food contact materials and products, the total migration amount of the food contact

materials and products can be measured under test conditions equivalent to or more

stringent than the specific migration testing, and conduct screening.

6.2 Residue amount screening

For the specific migration (total) amount of a certain substance (type) in food contact

materials and products, screening can be carried out after conversion using the residue

amount of the substance (type) in the food contact materials and products. When

converting, it shall be assumed that all measured residual substances migrate into the

food or food simulant. Calculation is based on the volume or mass of the product

expected to contact food and the corresponding contact area.

6.3 Screening for amount used

For the specific migration (total) amount of a certain substance (type) in food contact

materials and products, screening can be carried out after conversion based on the usage

amount of the corresponding substance in the production of the food contact materials

and products. When converting, it shall be assumed that the added substance(s) will all

migrate into the food or food simulant. Calculation is based on the volume or mass of

the product expected to contact food and the corresponding contact area.

7 Chemical solvent substitution testing

7.1 For foods containing oil, chemical solvents such as 95% (volume fraction) ethanol,

n-hexane, n-heptane, isooctane, etc. can be used to replace oil-containing food

simulants to conduct chemical solvent substitution tests.

7.2 The chemical solvent substitution test shall adopt the most stringent test conditions

supported by scientific evidence and that can most truly reflect the migration status of

actual fat-containing foods or corresponding food simulants.

8 Migration testing result correction

8.1 Area to volume ratio

8.1.1 The ratio (S/V) of the contact area (S) to the food mass or volume (V) of food

contact materials and products used in the calculation of migration testing results shall

be able to reflect the most stringent actual use situation (such as the smallest packaging).

The density of liquid food shall be calculated as 1 kg/L.

8.1.2 For container-type food contact materials and products, if the container has a scale

or a nominal capacity and no minimum capacity requirement, V is measured in terms

of the volume corresponding to the maximum scale or nominal capacity, and S is

measured in terms of the inner surface area corresponding to the maximum scale or

nominal capacity. If the container has a minimum capacity requirement, V is measured

in terms of the volume corresponding to the minimum scale, and S is measured in terms

of the inner surface area corresponding to the minimum scale. If the container has no

scale and no nominal capacity, the distance between the liquid level of the food simulant

and the upper edge (overflow surface) of the hollow product shall be 1 cm or the S/V

corresponding to 4/5 of the volume of the hollow product to be heated and boiled shall

be selected for calculation of migration testing results.

8.1.3 For food contact materials and products such as bottle caps, gaskets, and sealing

rings, the calculation of S/V shall include the area or volume of the container to which

they are adapted. If there is no information on suitable containers, it shall be calculated

based on the migration amount in each product (such as mg/piece).

8.1.4 The S/V of conveyor belts, pipes, gaskets, valves and other spare parts in food

processing equipment that are in dynamic contact with food shall be estimated based

on their actual contact with food (such as based on equipment parameters).

8.1.5 When the S/V is unknown, the migration testing results are calculated using 6 dm2

of food contact materials and products in contact with 1 kg of food.

8.2 Fat correction factor

8.2.1 For foods with a fat content of more than 20%, the fat reduction factor (FRF) shall

be used to correct the specific migration amount of lipophilic substances according to

formula (1).

8.2.2 Principles of using FRF.

a) The specific migration level in the food or food simulant must not exceed 60

mg/kg before correction using the FRF factor;

b) When comparing to a specific migration limit, the specific migration testing result

shall be divided by the FRF.

8.2.3 FRF shall not be used for calibration under the following circumstances.

a) Special food contact materials and products for infants and young children;

b) Substances with a specific migration limit of "not to be detected";

c) When the S/V is unknown, use 6 dm2/kg to calculate the specific migration amount.

8.3 Correction factors for fatty food simulants

8.3.1 The migration testing results of vegetable oil and other fat-containing food

simulants in Table A.1 shall be divided by the correction factor of fat-containing food

simulants (the corresponding value in Table A.1). Compliance determination is made

after calibration.

8.3.2 The correction factor for food simulants containing fats and oils is not applicable

to substances with a specific migration limit of "not to be detected".

8.4 The test results of the specific migration amount of lipophilic substances in oil-

containing food simulants shall be corrected by using the product of the fat correction

factor and the correction factor of oil-containing food simulants. When the product of

the two correction factors is not greater than 5, it shall be calculated as the actual product.

When it is greater than 5, it shall be calculated as 5.

9 Selection of migration testing results

9.1 For reused food contact materials and products, the same test sample or the same

specimen shall be subjected to migration testing three times. Use 1 new food simulant

each time. The result of the third migration testing shall be the final result of the

migration testing. If there is indeed evidence that the migration amount in the first

migration testing does not exceed the migration limit and the migration amount in the

second and third migration testing will not increase, multiple migration testing will not

be conducted. Potassium permanganate consumption and heavy metals (in Pb) are

tested only once.

9.2 For reused food contact materials and products, for substances that cannot be

detected with specific migration limits, the results of the first migration testing shall be

used as the final migration testing result.

9.3 When the screening results meet specific migration (total) limit requirements, the

screening results can be used as the final result. When the screening results do not meet

the limit requirements, specific migration testing shall be conducted in accordance with

the requirements of this Standard. Take the migration testing results as the final result.

When migration testing techniques are not feasible, screening results shall be used as

the final result.

9.4 When the chemical solvent substitution test results meet the limit requirements, the

substitute test results can be used as the final result. When the chemical solvent

substitution test results do not meet the limit requirements, a migration testing for oily

food simulants shall be conducted. Take the migration testing results as the final result.

When it is not technically feasible to use oily food simulants for migration testing, the

alternative test results shall be used as the final migration testing results.

Annex A

Selection of food categories and food simulants

A.1 The food categories that food contact materials and products are expected to come

into contact with and the selection of corresponding food simulants shall comply with

the provisions of Table A.1.

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