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 BfRshort forGerman Federal Institute for Risk Assessment'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 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 nmshort fornanometre to 100 nmshort fornanometre;
- the particles have an elongated shape such as a rod, fibre or tube, where two external dimensions are smaller than 1 nmshort fornanometre and the other dimension is larger than 100 nmshort fornanometre;
- the particles have a plate-like shape, where one external dimension is smaller than 1 nmshort fornanometre and the other dimensions are larger than 100 nmshort fornanometre.
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.
Frequently asked questions
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 BfRshort forGerman Federal Institute for Risk Assessment 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):
The European Food Safety Authority (EFSAshort forEuropean Food Safety Authority) has assessed nanomaterials used in plastics that come into contact with food. The assessments are published in the EFSAshort forEuropean Food Safety Authority Journal. The approved nanomaterials are listed in Annex I of the corresponding Regulation (EU) No. 10/2011.
The European Food Safety Authority (EFSAshort forEuropean Food Safety Authority) 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.