Risk assessment of food contact materials

Abstract

In the EU, any material or article intended to come into contact with food, which is placed on the market, has to comply with the requirements of the Regulation (EC) No 1935/2004 – the so called ‘framework regulation’ for food contact materials (FCM). FCM covers a wide range of materials, including plastics, paper, metal and glass, which contain chemicals that might migrate into food. These chemicals must not migrate into the foodstuff in quantities that could endanger human health, bring about an unacceptable change in the composition of the food, or bring about a deterioration in the organoleptic characteristics thereof. Despite of this general regulation, the safety of new and specific materials that are not covered must be assessed case-by-case. In addition, national authorities can set their own regulations, and in this context, the BfR sets recommendations, which are not legal norms, but represent a standard for the production of materials not subjected to any specific legislation and are well accepted by other European Commission member states according to the mutual recognition principle. The BfR Unit 74 is responsible not only to deal with chemical risk assessment of FCM but also to evaluate application dossiers to include new substances in the positive list of FCM chemicals. In the proposed EU-FORA programme, the fellow had the opportunity to gain experience in the evaluation of toxicological data from applicant dossiers and in the methodologies of migration tests performed in the laboratories. Moreover, the fellow also made a bibliographic review on scientific literature on the migration studies from starch-based materials.

Introduction

Food contact materials (FCM) are all materials intended to come into contact with food during its production, processing, storage, preparation and serving. FCM include a wide variety of materials such as plastics, paper, ceramics, metals, rubbers and inks used in food packaging and containers, industrial equipment kitchenware and tableware. Once the material is in direct or indirect contact with food, it can release its compounds, which might migrate into foodstuff. Migration is the process of mass transfer of chemical compounds from packaging to food and is affected by different factors: nature of food and material, type and temperature of contact, properties and concentration of migrating substances present in the material (Arvanitoyannis and Kotsanopoulos, 2013).

During the manufacture of FCM, many substances, which can contain impurities, are incorporated to achieve the required properties. The interaction between the different compounds present in the material can originate non-intentionally added substances (NIAS), which can also migrate into food. The Commission Regulation (EU) No 10/2011 (European Commission, 2011) on plastic materials and articles intended to come into contact with food defines NIAS as ‘an impurity in the substances used or a reaction intermediate formed during the production process or a decomposition or reaction product’.

In the European Union (EU), in order to be considered safe, materials and articles intended to be in contact with food must comply with the Regulation (EC) No 1935/2004 (European Commission, 2004), which is considered the framework regulation for FCM. It sets general requirements for FCM, that shall be manufactured in compliance with good manufacturing practices, according to Commission Regulation (EC) No 2023/2006 (European Commission, 2006a), and must not transfer their constituents to food in quantities that could ‘(a) endanger human health, (b) bring about unacceptable change in the composition of the food or (c) bring about a deterioration in the organoleptic characteristics thereof’.

The EU rules on FCM can be of general scope, i.e. apply to all FCM, or apply to specific materials only. EU law regulation may be complemented with member states national legislation, in accordance with Article 6 of Regulation (EC) No 1935/2004 (European Commission, 2004), if specific EU rules do not exist.

In Germany, although the BfR Recommendations on Food Contact Materials (https://bfr.ble.de/kse/faces/DBEmpfehlung_en.jsp) are not legal norms, they ‘represent the current state of the scientific and technical knowledge for the conditions under which consumer goods made of high polymer substances meet the requirements of § 31 paragraph 1 of the German Food and Feed Code (LFGB) and of the Regulation (EC) No 1935/2004 (European Commission, 2004) in respect to their health safety’. BfR Recommendations are also well accepted by other European Commission member states due to the mutual recognition principle.

Manufacturers that want to include new substances in the BfR Recommendations on Food Contact Materials must send an application following the EFSA Note for Guidance for the Preparation of an Application for the Safety assessment of a Substance to be used in Plastic Food Contact Materials (EFSA CEF Panel, 2008) (https://efsa.onlinelibrary.wiley.com/doi/full/10.2903/j.efsa.2008.21r). The evaluation of dossiers include the verification of the compliance with the requirements set in the EFSA Note of Guidance and the assessment of the scientific information provided by the applicant.

Enamels

Enamel is a glassy, vitreous and usually opaque substance. It is used as a protective or decorative coating on metal, glass or ceramic ware. Vitreous enamel, or porcelain enamel, is produced by fusion of powdered glass applying fire, between 750°C and 850°C. After melting, it can be applied on surfaces that withstand this high temperature and then hardens resulting in a smooth vitreous coating.

As a FCM, enamel has been tested in the same way as ceramic materials, i.e. at room temperature for 24 h using acetic acid 4% as a food simulant (FS). However, these conditions do not mimic properly the possible uses of enamelled fcm. Thus, the International Organization for Standardization (ISO) (2022) published a document (DIN EN ISO 4531:2022–04 ‘Vitreous and porcelain enamels - Release from enamelled articles in contact with food - Methods of test and limits’) setting migration conditions and release limits for metals from vitreous and porcelain enamelled articles in contact with food.

Biomaterials

Bioplastics are being developed as an alternative to fuel-based plastics as a result of current environmental concerns about the production and disposal of conventional plastic materials. Bioplastics can be either bio-based, biodegradable or both. Polybutylene adipate terephthalate (PBAT), polycaprolactone (PCL), polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), polylactic acid (PLA) and thermoplastic starch (TPS) are some examples of bioplastic materials (European Bioplastics, 2018). As starch is naturally present in the human diet, it is generally considered safe when used as FCM. However, when it undergoes chemical modification and/or additives are incorporated, migration tests to identify and quantify possible compounds and/or NIAS that could migrate into food should be carried out.

Description of work programme Aims

The objective of the programme was to acquire knowledge on how risk assessment of FCM is performed. In this way, first, the fellow participated in the evaluation of toxicological data from dossiers for adding new substances to the BfR Recommendations on Food Contact Materials. It included analysis of toxicological data of in vivo and in vitro tests to verify the agreement with EFSA's Note for Guidance. Later on, the fellow was involved in practical work conducted in the German National Reference Laboratory for Food Contact Materials, which is located at the BfR. In this occasion, the fellow learned how to conduct a migration test in the laboratory and how to handle the available equipment. In parallel, the fellow made a bibliographic research on risk assessment of biomaterials, focused on starch-based materials intended to be used as FCM, which will be further detailed in this document.

Activities/methods

The activities performed and methods applied during the programme are listed below:

1. Scientific evaluation of one dossier, whose data will not be included due to confidential agreement. It involved the review of toxicological data of a substance to be included in the BfR Recommendations on Food Contact Materials. The dossier was submitted by the applicant in accordance to the EFSA Note for Guidance. Due to data confidentiality, the data related to this item will not be detailed in the next sub sessions.
2. Determination of release of the elements aluminium, antimony, arsenic, barium, cadmium, cobalt, chromium, copper, iron, lead, lithium, manganese, molybdenum, nickel, titanium, vanadium and zinc from enamelled plates into food and food simulants (FS). Apparatuses according to DIN EN ISO 4531:2022–04 (International Organisation for Standardisation, 2022) were used for the release test and inductively coupled plasma-mass spectrometry (ICP-MS) was used to quantify the elements. The release tests were conducted at 70°C and 95°C for 2 h, in accordance to ISO 4531. The FS proposed were artificial tap water acidified with citric acid to pH 3.5, citric acid 0.5%, acetic acid 3% and 4%, respectively.
3. Bibliographic research on accurate definition of biomaterials, and on migration results, focusing especially on starch-based materials. For more details see Section 2.2.2.

Migration study

FCM cover a wide range of materials, including ceramic and vitreous materials; enamel and enamelled materials are one of them. It can be applied on the surface of metal items with protection or decorative purposes. Metals such as lead and cadmium are present in those materials and can migrate into food when used as FCM. However, not only those metals are present but also aluminium, arsenic, chromium, nickel and others can be detected in those materials, which can bring risks to human health if they migrate into foodstuff in quantities resulting in exceedance of health-based guidance values.

As enamels are very resistant to high temperatures, they can be used as kitchenware coatings and be heated during food preparation. As elements migration is dependent on the temperature of contact and the nature of food, it is important that the migration tests are conducted in a way that the conditions simulate the worst-case scenario, e.g. with respect to food simulant, temperature and time.

The preliminary tests were conducted with the objective to make the fellow familiar with the release test apparatus, according to ISO 4531:2022 (International Organisation for Standardisation, 2022), and with an ICP-MS equipment. Water MilliQ was used and the chosen conditions were 70°C and 95°C for 2 h in order to mimic the use of enamelled kitchenware used for cooking, such as pans and cake pans. The tests were performed in the German National Reference Laboratory for FCM, located at the BfR.

The migration vessels are made of borosilicate glass, cylindrical-shaped with an internal diameter (d) of 80 mm and a height of 36 mm. Between the cylinders and plates, silicon rubber rings with the same internal diameter of the vessels are used to seal the chambers properly and avoid leakage. Each silicon rubber has a thickness of 2 mm, so then, when the chambers are assembled, the total height (h) is 40 mm as silicon rings are placed in both ends in contact with the sample. Given that, it is possible to calculate the volume (V) of FS, multiplying the contact surface area (S) by the height of the chamber.[Image Omitted. See PDF][Image Omitted. See PDF]The apparatus was assembled in order to have three chambers (Figure 1). Thus, there were two surfaces of releasing enamel material in each chamber. If it is the case, the surface area (S) might be multiplied by 2. It is important that the chambers are filled completely in order to have correct surface and volume for migration calculation. Element concentration in the FS was determined via ICP-MS. Three consecutive tests were performed on the same day and only the FS solution of the third test was analysed in order to account for repeated use of enamel articles. Blank tests were also conducted together with the samples.

Figure 1. Schematic representation of a release test apparatus, according to ISO 4531:2022, with three testing chambers

In order to get reproducible results, it is very important to closely follow the conditions set by the ISO – especially keeping the temperature constantly in a very narrow range. To ensure this, tests were conducted prior to analysis to establish a method representing hot fill conditions (i.e. pouring boiling liquid food/drink into a fillable article and let it cool down). The method was optimised to keep the temperature of the FS at 70 ± 2°C or 95 ± 2°C, respectively. Therefore, the temperature was monitored every 60 s.

Risk assessment review for starch-based materials used as FCM

Biopolymers have been widely explored as a more eco-friendly alternative to plastics derived from petroleum. There are already a large number of companies producing biomaterials, usually blended with conventional plastics, to be applied as FCM. Nevertheless, biopolymers present some drawbacks that must be overcome, such as low stability, poor mechanical and barrier properties. Therefore, additives are usually incorporated in their production to achieve the desired properties (Scarfato et al., 2015). Those additives and possible NIAS, derived from their degradation or interaction with polymers or other additives, might migrate when in contact with food. It is necessary and importance to perform a risk assessment for these new materials in accordance to EFSA's Note for Guidance.

Starch is one of the most abundant macronutrients in nature and is composed by amylose and amylopectin (Figure 2). It has good potential to become a raw material in the manufacture of bioplastics, thus, there is currently a huge amount of researches on biomaterials using both native and modified starch (García-Guzmán et al. 2022). However, most of the researches do not focus on the safety aspects of the materials, and only few of them report results of migration studies.

Figure 2. Chemical structure of (a) amylose and (b) amylopectin

Regulation (EU) No 10/2011 (European Commission, 2011) includes biomaterials in its scope if they are produced by a conventional polymerisation process, by microbial fermentation or by chemical modification of natural polymers; so, materials based on native starch are not included in its scope. In the BfR Recommendations XXXVI on paper and board for food contact and XXXVI/2 on paper and paperboard for baking purposes, native and modified starches are listed as production aids and sizing agents.

According to Regulation (EC) No 1907/2006 (European Commission, 2006b), concerning Registration, Evaluation, Authorisation and Restrictions of Chemicals (REACH), non-chemically modified substances obtained from natural sources are exempted from registration, excepted those which are dangerous, flammable, skin or eye irritants, or persistent, bio accumulative and toxic, or very persistent and very bio accumulative.

Following those regulations, and taking into account Article 3 of Regulation (EC) No 1935/2004 (European Commission, 2004), the use of pure native starch as a FCM is not submitted to any previous registration or risk assessment. However, starch-based materials are brittle and present poor water permeability barrier, which makes the use of additives or blends very common to manufacture bioplastics with suitable properties.

The fellow carried out a bibliographic study on Scopus scientific database of the last five years using the combinations of keywords presented in Table 1. However, the large number of publications resulting from the search for ‘bioplastics’, ‘biopolymers’ or ‘biomaterials’, they include a wide range of applications other than FCM, such as medical, automotive, agricultural and others. Also, the studies on starch covered a wide range of different subjects not related to FCM. It could be noticed that even when the researchers published data on migration studies, most of them focused on the migration process modelling rather than the safety aspects. The fellow evaluated the available publications, extracted data on use, possible additives, migration and risk assessment considerations. From reviewing these, a prioritisation for necessary information and evaluation was concluded in order to improve risk assessment for starch based bioplastics in contact with food.

Table 1 Keywords and combinations in Scopus on 15 July 2022

Scopus – keyword	Total	2022	2021	2020	2019	2018
Bioplastic(s)	2,253	424	694	473	373	289
Biopolymer(s)	17,688	2,704	4,730	3,928	3,299	3,027
Biomaterial(s)	42,431	5,198	10,249	9,354	9,194	8,436
(biobased OR bio-based) AND plastic(s)	1922	352	539	409	357	265
(biobased OR bio-based) AND material(s)	6,518	1,167	1830	1,435	1,182	904
Biodegradable AND plastic(s)	5,164	967	1,432	1,068	980	717
Biodegradable AND polymer(s)	13,301	1978	3,379	2,882	2,638	2,424
Biodegradable AND material(s)	14,762	2,248	3,799	3,251	2,942	2,522
Bioplastic(s) AND (food AND contact AND material(s))	23	3	10	6	2	2
Biopolymer(s) AND (food AND contact AND material(s))	86	11	21	23	17	14
Migration AND bioplastic(s)	18	2	6	2	7	1
Migration AND biopolymer(s)	220	24	57	45	64	30
Migration AND biomaterial(s)	1701	180	429	399	374	319
(risk AND assessment) AND bioplastic(s)	24	8	9	2	4	1
(risk AND assessment) AND biopolymer(s)	46	10	15	6	11	4
(risk AND assessment) AND biomaterial(s)	282	35	66	53	61	67
Starch	34,823	5,165	8,724	7,659	6,913	6,362
Starch AND (food AND contact AND material(s))	85	17	26	13	17	12
Migration AND starch	239	46	66	49	42	36
(risk AND assessment) AND starch	1,074	146	284	262	187	195

Conclusions

The EU-FORA programme was an opportunity for the fellow to acquire theoretical and practical knowledge on chemical risk assessment of FCM. First, the fellow was placed together with the experts on Safety on Food Contact Materials and could participate on the evaluation of a dossier of a substance to be included in the BfR Recommendations list. Then, the fellow was invited to carry on a literature review on the safety of bioplastics intended to be used as FCM, with special attention to starch-based materials. In parallel, the fellow followed a laboratory work on preliminary tests carried out in the German National Reference Laboratory for food contact materials, located at the BfR. The aim of this project was to establish proper methodologies to use migration cells for testing of enamel articles under hot fill conditions.

All in all, the programme not only allowed the fellow to learn different tools and gain expertise to assess risks related to food contact materials, but also has been a unique opportunity for the fellow to build connections with experts and outstanding professionals in food risk assessment.

Disclaimer

The results of the risk assessment review for starch-based materials used as FCM as well as the results of the migration studies are intended to be published in a peer-reviewed journal. In order to avoid copyright claims, they were not included in the technical report.

Abbreviations
• BfR
• Bundesinstitut für Risikobewertung
• d
• internal diameter of the releasing material in the testing chamber
• FCM
• food contact material
• FS
• food simulant
• h
• total height of the glass chamber
• ICP-MS
• inductively coupled plasma-mass spectrometry
• LFGB
• German abbreviation for German Food and Feed Code
• NIAS
• non-intentionally added SUBSTANCES
• PBAT
• polybutylene adipate terephthalate
• PCL
• polycaprolactone
• PHA
• polyhydroxyalkanoate
• PHB
• polyhydroxybutyrate
• PLA
• polylactic acid
• REACH
• Registration, Evaluation, Authorisation and Restrictions of Chemicals
• S
• surface area of the sample in the testing chamber
• TPS
• thermoplastic Starch
• V
• volume of food simulant inside the testing chamber

Appendix A – Training Activities

Type of event	Title	Contribution	Location	Date
Meeting	27th Toxicology Subcommittee of the BfR Commission for Consumer Goods	Oral Presentation	BfR	9.11.2021
Training	Occupational safety	Attendance	BfR	14.1.2022
Training	Introduction to the Quality Management System	Attendance	BfR	15.2.2022
Meeting	28th Toxicology Subcommittee of the BfR Commission for Consumer Goods	Attendance	Online	26.4.2022
Meeting	Meeting of the BfR Commission for Consumer Goods	Attendance	Online	27.4.2022
Seminar	Product analytics	Attendance	Online	5.5.2022
Seminar	Control of procedures and evaluation strategies	Attendance	Online	17.5.2022
Training	Biological Substance and Genetic Engineering Safety Ordinance	Attendance	Online	1.6.2022
Seminar	Fiber- and nano-toxicology	Attendance	Online	14.6.2022
Conference	ONE Conference	Attendance	Brussels	21–24.6.2022