Health risk assessment of nanomaterials

Whether nanomaterials or products containing them can pose health risks to consumers cannot be answered in general terms. In general, the focus of the BfR's scientific risk assessment are intentionally produced nanomaterials that are for example used in numerous consumer goods.

Compared to their conventional counterparts, nanomaterials have altered and, in some cases, novel properties and functions that make them interesting for many areas of application, but also deserve special attention from a regulatory perspective. Production volumes and the variety of forms are continuously increasing, which can also lead to increased and possibly new types of exposure for consumers, for example if nanomaterials are released from products.

Definition: The European Commission published a recommendation on the definition of nanomaterials for the first time in 2011 (2011/696/EU), which has been updated in 2022 (2022/C 229/01). The term "nanomaterial" covers materials consisting of particles in solid state, present on their own or bound as constituent parts of aggregates or agglomerates, provided that 50 % or more of the number of particles fulfil at least one of the following conditions:

• one or more external dimensions of the particles are in the size range 1 nm to 100 nm;
• the particles have an elongated shape such as a rod, fibre or tube, where two external dimensions are smaller than 1 nm and the other dimension is larger than 100 nm;
• the particles have a plate-like shape, where one external dimension is smaller than 1 nm and the other dimensions are larger than 100 nm.

This updated recommendation is intended to serve as a basis for the definition of nanomaterials in various areas of legislation. However, the Commission also allows certain amendments or derogations in specific areas of legislation, for example excluding certain materials from the scope of application of specific legislation or legislative provisions even if they are nanomaterials according to this recommendation. It may likewise be considered necessary to develop regulatory requirements for additional materials not falling under the definition of the present recommendation in the context of specific legislation.

Further selected information on the definition of certain terms, including the definitions in various legislations can be found in the selected Questions and answers on nanomaterials .

Health risks of nanomaterials

From a health risk assessment perspective, products in which nanomaterials are present in unbound form or from which they are readily released should be considered in particular.

Compared to conventional materials, nanomaterials have altered and, in some cases, novel properties and/or functions. This raises questions that the BfR specifically examines in its risk assessment:

• Intake, distribution in the body and excretion (toxicokinetics): Due to their small size, nanomaterials can overcome some body barriers more easily and have a different distribution in the body than the corresponding non-nanoscale materials.
• Reactivity: Nanomaterials have a large specific surface area (surface-to-volume ratio), which is often associated with greater reactivity. This poses a risk for inflammatory reactions, which can lead to organ damage if prolonged.
• Persistence in the body (biopersistence): Some nanomaterials have a very long residence time in individual organs, so that the quantities increase over time and thereby possibly cause damage to health due to the reactivity of the particles.

Examination of intake routes

In the risk assessment of nanomaterials, due to the broad application in different products, several uptake pathways are of interest: via the respiratory tract (inhalation), via the digestive tract (oral) and via the skin (dermal).

Intake via the respiratory tract

Scientists regard the inhalation of nanomaterials to pose the greatest risk of health impairment. This is because it can lead to inflammatory processes in the lungs, which in chronic cases can lead to organ damage and tumour development. A particular risk is posed by biopersistent fibres with critical dimensions, which have asbestos-like effects and can cause tumours in the lungs and peritoneum (mesothelioma). Another risk is that when nanomaterials are inhaled, a small proportion can reach other organs. There also is the possibility that signalling molecules are released (e.g., triggered by inflammatory processes), which then mediate adverse effects in other organs.

Intake via the digestive tract

Whether there are risks associated with the intake of nanomaterials via the gastrointestinal tract has not yet been conclusively clarified. However, it has also been shown that a small proportion of particles can be transported to other organs following oral intake. Here, too, there is the possibility that signalling molecules are released, for example, via inflammatory processes and then mediate adverse effects in other organs.

Intake via the skin

According to the current state of knowledge, the amount of nanomaterials absorbed through intact human skin is very low.

Challenges in the health risk assessment of nanomaterials

In a risk assessment, each nanomaterial must be examined separately and each application must be considered individually. The basic principles of a health risk assessment also apply to nanomaterials: possible health hazards (harmful effects) and actual exposure must be considered. However, the risk assessment of nanomaterials has some specific challenges:

• Physicochemical characterisation: In the context of physicochemical characterisation, many other parameters are relevant due to the particulate nature. In addition, characterisation must also be carried out in different biologically relevant environments, as some physicochemical properties can change depending on the environment.
• Exposure data: Reliable data on consumer exposure is often lacking.
• Test guidelines and guidance documents: The adaptation of test guidelines (TGs) and guidance documents (GDs) of the Organisation for Economic Co-operation and Development (OECD) for the health risk assessment of nanomaterials has not yet been completed.
• Assessment concepts and screening procedures: Because of the large number of variants, the development of new assessment concepts (e.g., group formation) and reliable screening procedures are of particular importance.

Nanomaterials assessed in consumer-related applications

Risk assessments have been carried out for a large number of nanomaterials used in cosmetic products. An overview of the assessments can be found on the website of the EU Commission's Scientific Committee on Consumer Safety (SCCS) (https://health.ec.europa.eu/scientific-committees/scientific-committee-consumer-safety-sccs/sccs-opinions_en).

The European Food Safety Authority (EFSA) has assessed nanomaterials used in plastics that come into contact with food. The assessments are published in the EFSA Journal. The approved nanomaterials are listed in Annex I of the corresponding Regulation (EU) No. 10/2011.

The European Food Safety Authority (EFSA) has also assessed Iron hydroxide adipate tartrate (IHAT) in nanoform in accordance with the Novel Food Regulation (EU) 2015/2283, which has been authorised by the European Commission as a source of iron in food supplements since 2022 (EU 2022/1373).

Substances whose nanoforms are relevant for consumer products were also assessed under the overarching EU chemicals regulation REACH.

Risk assessment of nanomaterials in different chemicals legislations

The health risk assessment of nanomaterials takes place within the framework of different chemicals legislations.

The overarching EU Regulation on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH, (EC) No. 1907/2006 and several product-specific regulations have already been adapted to the requirements of nanomaterials. The current status in the most important areas is described in the following.

Not all products are regulated by their own legal regulations. However, all manufacturers are obliged by the European Product Safety Directive and from December 13 2024 by the Regulation (EU) 2023/988 on general product safety to guarantee the safety of their products.

Nanomaterials in the European chemicals legislation (REACH)

In the European chemicals legislation, the REACH Regulation (Regulation concerning the Registration, Assessment, Authorisation and Restriction of Chemicals (EC) No. 1907/2006) has been amended twice to take into account the special features of nanomaterials. The revised annexes of Regulation (EU) No. 2018/1881, which came into force on January 1, 2020, prescribe how to characterise the “nanoforms” of a substance and specify standard information requirements for nanoforms which must be submitted, in dossier format, by manufacturers and importers for registration. Nano-specific information requirements include information on substance identity and physical-chemical characterisation (described in Annex VI of the REACH Regulation), as well as human and environmental toxicological endpoints (depending on the tonnage described in Annexes VII, VIII, IX and X of the REACH Regulation). In addition, Annex II of the REACH Regulation was adapted with Regulation (EC) No. 2020/878, which describes the requirements for the preparation of safety data sheets.

The European Chemicals Agency (ECHA) supports the implementation of the legal requirements for nanomaterials through series of technical guidance, e.g., for the registration and substance identification of nanoforms or for the health assessment of nanoforms. In addition, as part of dossier evaluation, the compliance with the requirements is checked. For selected substances (including nanomaterials or the nanoforms of a substance) for which concerns are identified, a Member State can commit to perform substance evaluation in collaboration with ECHA. In addition to the information contained in the dossier, substance evaluation also considers other scientific evidence to draw a conclusion whether a possible health risk arising from the use of the nanomaterial has been adequately controlled.

Legal regulation of nanomaterials in cosmetic products

In accordance with the EU Cosmetics Regulation (EC) No. 1223/2009, nanomaterials are explicitly accounted for in cosmetic products. According to Article 16 of the EU Regulation, cosmetic products containing nanomaterials have to be reported to the EU Commission since January 11, 2013. Cosmetic products that contain nanomaterials must be notified electronically six months before being launched on the market, in accordance with Article 13 of the EU Regulation. Comprehensive information about the nanomaterial (specification of the physical and chemical properties, estimation of the quantities being distributed, foreseeable exposure conditions, as well as the toxicological profile and safety data) must be provided. Exceptions are cosmetic products that contain nanomaterials in accordance with the requirements of Annex III, as well as nanomaterials that are used as dyes, UV filters or preservatives. The European Commission published a report in July 2021 on the use of nanomaterials in cosmetic products: https://eur-lex.europa.eu/legal-content/DE/TXT/PDF/?uri=CELEX:52021DC0403&from=EN.

If the EU Commission has concerns about the safety of a notified nanomaterial, it requests a scientific committee of experts - the Scientific Committee on Consumer Safety (SCCS) - to issue an opinion within six months (Article 16(4)). In cases where further data and clarifications are required, there is a further six-months period for assessment after receipt of the requested information. Certain categories of cosmetic ingredients - e.g., dyes, UV filters and preservatives, including their nanoforms - can only be used in cosmetic products if they have assessed by the SCCS and have been included by the European Commission in Annexes IV - VI of the EU Cosmetics Regulation (Article 14(1)(c) to (e)). The risk assessment is based on the SCCS Guidance on the assessment of nanomaterials in cosmetic products (SCCS/1655/23) and the SCCS Notes of Guidance in the latest version (SCCS/1467/22). The SCCS assessment forms the basis for regulatory decisions (ban of a nanomaterial in cosmetic products or inclusion in one of the positive lists of the EU Cosmetics Regulation).

In the case of cosmetic products containing ingredients in the form of nanomaterials, a corresponding statement must be made in the list of ingredients. The names of these ingredients must be followed by the word "nano" in brackets. The labelling requirement applies to all nanomaterials in cosmetics.

At the same time, the European Commission is reviewing the provisions of the Regulation relating to nanomaterials in the light of scientific progress and may propose necessary amendments.

Legal regulation of nanomaterials in food packaging

Food packaging is subject to the overarching Regulation (EC) No. 1935/2004. It provides general regulation for materials and objects that are intended to come into contact with food. This regulation does not contain any nano-specific adaptations nor does it define the term nanomaterial. However, it stipulates very generally that, in principle, all materials and objects shall be manufactured in such a way that, under normal or foreseeable conditions of use, they do not release any constituents into food in quantities that are likely to hazardous to human health, cause an unacceptable change in the composition of the food or impair the organoleptic properties (i.e., taste, smell, colour) of the food.

In addition, Regulation (EU) No. 10/2011 governs plastics in food contact more precisely. However, this does not define the term nanomaterials either. Rather, it generally stipulates (in Article 9) that substances in nanoform may only be used if they have been explicitly assessed and included in Annex I accordingly.

Scientific assessment falls within the remit of the European Food Safety Authority (EFSA). The EFSA guidelines for the assessment of nanomaterials in the food and animal feed chain, which also covers food contact materials, form the basis for risk assessment ( EFSA Journal Vol 19, Issue 8, 2021, e06768). EFSA has already assessed some nanomaterials for uses in plastics and the European Commission has approved them on the basis of a positive assessment. The reason for the decision was that the relevant nanomaterials cannot migrate from the plastic into the food. The approved nanomaterials (e.g., zinc oxide, silicon dioxide, titanium nitride, soot, nanoclay) are listed in Annex I of Regulation (EU) No. 10/2011.

The BfR issues recommendations for areas that are not yet regulated by legal provisions, such as silicones, natural and synthetic rubber or paper, card and cardboard for contact with food. Unless otherwise stated, the entries in the BfR recommendations on food contact materials are based on the risk assessment of substances with non-nanosized particle and do not apply to engineered nanomaterials.

Legal regulation of nanomaterials in food

Food is subject to Regulation (EU) 2015/2283 on novel foods (Novel Foods Regulation). All foods that consist of or contain engineered nanomaterials are considered novel and require a separate assessment by the European Food Safety Authority (EFSA) and authorisation by the European Commission in accordance with the Novel Foods Regulation (EU) 2015/2283. The EFSA guidelines for the assessment of nanomaterials in the food and animal feed chain form the basis for risk assessment (EFSA Journal Vol 19, Issue 8, 2021, e06768). To date, there is only one engineered nanomaterial that has been authorised for use in food in the EU under Regulation (EU) 2015/2283. This is iron hydroxide adipate tartrate (IHAT) in nanoform, which has been authorised as a source of iron in food supplements since 2022 (EU 2022/1373).

The use of food additives is regulated in various legislations. EU Regulation (EC) No. 1333/2008, Regulation (EU) No. 1129/2011 and other amending regulations form the basis. During approval, food additives are assessed with regard to their effects on health as the form in which they are to be launched on the market. This also falls within the remit of the European Food Safety Authority (EFSA). However, different approved food additives have a very broad particle size distributions, and particles smaller than 100 nm (nanometres) have already been detected in these additives. The proportion of nanoparticles varies and can be 10 to 30% by total particle numbers. However, since the particles with one or more external dimensions in the range from 1 to 100 nm make up less than 50% of the number size distribution, they do not fall under the definition of nanomaterials. However, in accordance with the EFSA's guidance document on technical requirements for regulated food and feed, the extent to which conventional materials contain nanoscale particles must be examined as part of a risk assessment and, if necessary, this proportion must then be assessed separately, taking nano-specific requirements into account. For food additives that have already been approved and that are to be used in a form other than the previously tested and approved form, e.g., as nanoparticles, Regulation (EC) No. 1333/2008 provides for re-evaluation and, if necessary, a new authorisation is prerequisite for placing on the market.

With the adoption of the Food Information Regulation (EU) No. 1169/2011, labelling of all ingredients that are present in the form of engineered nanomaterials has been mandatory since 2014. These must be clearly listed in the list of ingredients, followed by the word "nano" in brackets.

Legal regulation of nanomaterials in textiles

Textiles such as clothing or bedding are generally subject to the provisions of the German Food, Commodities and Feed Code (Lebensmittel-, Bedarfsgegenstände- und Futtermittelgesetzbuch). With regard to nanomaterials, there is no specific legal regulation for textiles. However, the treatment of textiles with biocides has been regulated by the Biocides Regulation (EU) No. 528/2012 since 2013.

For example, to date there is no regulation for finishing textiles with titanium dioxide as UV protection or with carbon nanotubes to increase the resilience of the fibres. However, manufacturers and distributors are responsible under the Food and Feed Code and the European Product Safety Directive and from December 13 2024 the Regulation (EU) 2023/988 on general product safety to guarantee the safety of their products.

Legal regulation for nanomaterials in biocides

Biocides are subject to the EU Biocide Regulation (EU) No. 528/2012, which contains a definition of nanomaterials. In general, the Biocide Regulation requires a two-stage process. In the first step, a decision is made on the approval of the biocidal active substance within a European assessment procedure. The approved biocidal active substance are recorded in a positive list. Approval of an active substance does not include its nanoform(s). An active substance in nanoform must be assessed and approved separately and must also be specified explicitly as a nanoform. In the second step, the individual biocidal products containing this active substance must either be authorised by the member states or by the European Chemicals Agency (ECHA). The ECHA also maintains a corresponding register of all authorised products. If the biocidal products contain non-active substances in nanoform, the assessment of these fall within the scope of the REACH Regulation.

So far, only a few nanosized biocidal active substances have been assessed. One approved nanosized biocidal active substance is synthetic amorphous silicon dioxide (SiO₂) in product type 18 (insecticides, acaricides and products to control other arthropods).

In accordance with the EU Biocide Regulation, the names of all nanomaterials contained in the biocidal products must be indicated on the label, followed by the word "nano" in brackets.