ISO has published a new standard, ISO 4531:2018, for food contact vitreous and porcelain enamels. This standard establishes test conditions for a variety of applications and migration limits for 16 heavy metals.

SAFEGUARDS | Hardlines NO. 159/18

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In September 2018, the International Organization for Standardization (ISO) published ISO 4531:2018 [1] , a completely new (voluntary) standard for testing food contact enameled articles. This new standard replaces both ISO 4531-1:1998 [2] and ISO 4531-2:1998 [3], where the content from each (former) standard was combined and technically revised.

The new standard contains, inter alia, the following important provisions:

  • Defining test conditions (temperature and time) for products intended for the following applications:

    • Room temperature only

    • Hot fills

    • Grills and barbecues (short exposures)

    • High temperature applications, including cooking

  • Defining procedures for sample preparation, testing and the type of instrument for analytical measurements

  • Establishing limits for the migration of 16 heavy metals 

Highlights of the new standard for 16 heavy metals and their migration limits are summarized in Table 1.

ISO 4531:2018 ‘Vitreous and porcelain enamels – release from enameled articles in contact with food – methods of test and limits’ (Migration Limit (µg/l))
Item Element (symbol) Limit Item Element (symbol) Limit
1 Aluminum (Al) 5000 9 Lithium (Li) 480
2 Silver (Ag) 80 10 Manganese (Mn) 1800
3 Arsenic (As) 2 11 Molybdenum (Mo) 120
4 Barium (Ba) 1200 12 Nickel (Ni) 140
5 Cadmium (Cd) 5 13 Lead (Pb) 10
6 Cobalt (Co) 100 14 Antimony (Sb) 40
7 Chromium (Cr) 250 15 Vanadium (V) 10
8 Copper (Cu) 4000 16 Zinc (Zn) 5000

Table 1

On July 26, 2018, the German Federal Institute for Risk Assessment (Bundesinstitut für Risikobewertung, BFR) published Opinion No. 24/2018 [4] (the Opinion) for the migration of heavy metals from enameled grill grates. The methods used in the studies were, in part, from draft standard E DIN EN IS0 4531:2017-04, 4% acetic acid (room temperature, 24 hours) and 0.5% citric acid solution (100 °C, 1 hour). The report found significant quantities of aluminum, antimony, arsenic and nickel were released from certain enameled grill grates. In the absence of a legal binding set of migration limits for heavy metals for these food contact materials and articles, some of the released concentrations were found to exceed quantities derived from acceptable exposure levels without compromising health. The Opinion also recommended consumer exposure levels for some heavy metals from these products.

According to the Opinion, grills manufactured with steel or cast iron are often coated with enamel materials to protect against corrosion and to facilitate cleaning. Enamel materials are known to contain a variety of silicates and oxides derived from metals, including aluminum, antimony, arsenic, cadmium, chromium, cobalt, iron, lead, lithium and nickel.

It is also important to note the European Rapid Alert System for Food and Feed portal (RASFF portal) has a number of notifications relating to, among other things, the migration of heavy metals from food contact enameled articles. These include cadmium, cobalt, lead, lithium, manganese and nickel. 

SGS technical experts have extensive knowledge and testing experience in materials and articles in contact with food. They work to ensure that your products meet the appropriate regulations for food contact materials and pave the way for compliance. From overall migration test to expert advices on emerging regulations and compliance issues and documentation review, SGS is the partner to trust. Please do not hesitate to contact us for further information or visit our website.

For enquiries, please contact:

Hingwo Tsang
Global Information and Innovation Manager
t: +852 2774 7420

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