Risk research studies potential harmful effects of nanomaterials on human beings and the environment. It is intended to provide the basis for risk assessment and the creation of development and testing methods and strategies.
Risk assessment ensures that harmful effects of nanomaterials can be avoided at the production, application and waste disposal stages. It also facilitates the identification of safe utilisation options and the initiation of risk-free innovation processes.
For the risk assessment of conventional chemicals, a comparison is made between the toxicologically tolerable exposure levels and the anticipated exposure of human beings and the environment. A risk exists if the exposure level is higher than the level that is deemed to be safe. To assess the level of risk associated with chemicals, numerous physical, chemical, toxicological and eco-toxicological properties have to be determined with the aid of internationally standardised test methods.
Within the scope of the existing certification and registration procedures, an assessment strategy has to be applied that is based on the following principles:
- If the sales volume is low, the required quantity of data is lower than that required for chemicals with a high sales volume;
- An initial risk assessment is made on the basis of the acute toxicity, the physical-chemical properties and the persistence of a chemical;
- Predictions regarding long-term risks are based on findings obtained from well-studied chemicals with a similar structure or similar properties (quantitative structure activity relationship and read-across criteria);
- In the case of high production volumes, or if there are indications of chronic effects, test data regarding long-term toxicity and accumulation in organisms (bio-accumulation) will be requested.
2. Risk evaluation of nanomaterials
To assess the risks associated with nanomaterials, the same methodology can be applied as that used for conventional chemicals. However, attention has to be paid to certain specific characteristics of nanomaterials:
- Nanomaterials find their way into cells via different routes than conventional chemicals or particles in the micrometre range. They can reach other organs via the bloodstream and potentially trigger toxic effects;
- It is not yet possible to assess the bio-accumulation tendency on the basis of physical-chemical properties, and this means it has to be done experimentally;
- Not all test methods developed for conventional chemicals can be used for examining the properties of nanomaterials;
- Existing QSAR (quantitative structure activity relationship) methods and read-across criteria cannot be applied to nanomaterials;
- Existing models for assessing environmental behaviour cannot be used for nanomaterials.
This means that decisions concerning the data that are required for carrying out a risk assessment currently have to be taken on a case-by-case basis. This procedure is feasible, but it is too complex for both the industry and the relevant authorities. The methodology for risk assessment needs to be further developed and refined so that it takes account of the specific characteristics of nanomaterials. Future test strategies should ensure that nanomaterials that trigger long-term effects can be identified at an early stage, and tests will then only be required on animals if these are required for a more comprehensive risk assessment. Wherever possible, models should replace measurements and the “3 Rs” principle (replace, reduce, refine) should be applied in order to minimise the need for tests on animals and the use of resources.
3. Questions relating to risk research
Despite intensive research activity there are still gaps in knowledge that need to be filled by carrying out research. At both the national and the international level, research projects and joint efforts aimed at further developing test methods and strategies (e.g. OECD WPNM) are currently in progress. Research questions serve as the basis for planning and implementing projects in a targeted manner. To illustrate the areas of research that are ongoing or to be addressed in the near future, and which are of relevance to the authorities, a selection of questions is presented below:
Scientific questions relating to the assessment of the toxicity of nanomaterials
- How can the methodology for the assessment of the risks associated with nanomaterials be refined so that it will be possible to reliably identify those nanomaterials that potentially cause long-term effects, efficiently and without the needs for tests on animals?
- In the same way as conventional chemicals, the effects of hazardous nanomaterials are caused via toxicological chains (or “adverse outcome pathways”). By studying cell cultures (in vitro) it is possible to describe the individual steps of an adverse outcome pathway (referred to as “key events”) and examine whether any of these apply to a given nanomaterial. Which adverse outcome pathways are relevant for nanomaterials and which cell cultures can be used for measuring their key events?
- Which existing test methods for conventional chemicals need to be adapted in view of the special physical-chemical properties of nanomaterials, and how can this be done? Which new test methods need to be developed in order to measure nano-specific properties?
- What would be the minimal set of physical-chemical parameters that unequivocally describes a nanomaterial and enables its toxicological assessment?
- The distribution behaviour of nanomaterials in the human body and the environment is determined by other physical-chemical properties than those of conventional chemicals. Which properties determine distribution behaviour such as the bio-accumulation of nanomaterials, and how do existing models for predicting this behaviour need to be adapted?
Questions regarding the regulation of nanomaterials
- Chemicals legislation stipulates that chemicals and nanomaterials must be classified and labelled as hazardous substances. Do the classification criteria for chemicals (GHS, PBT) need to be adapted for nanomaterials, and if so, how?
- What form could harmonised datasets take for certification and registration procedures?
- Can adverse outcome pathways be used as the basis for forming groups of nanomaterials that can be tested using the same strategy?
4. Risk assessment tools
The development and standardisation of test methods and strategies for examining the specific properties of synthetic nanomaterials are currently in progress within both national and international bodies. Until such time as this process has been completed, a variety of tools for assessing risks and safely handling nanomaterials are available that have been developed within the scope of the “Synthetic Nanomaterials Action Plan”:
5. Risk information
The results of research on nanomaterials and their impacts on human beings and the environment may be viewed on the platform of the “DaNa – Data and Knowledge on Nanomaterials” project, which is receiving the support of the Federal Office of Public Health and the FOEN. This platform provides information about the nanomaterials contained in various products. For more detailed information, please refer to the links below.
Last modification 20.08.2018