Published on 12 March 2025

FAQ on the precautionary matrix for synthetic nanomaterials

• A high score can arise as a result of a lack of knowledge as well as by poor actual scores. Is a distinction made here in the precautionary matrix?

  No. Users evaluate this point in the precautionary matrix themselves. Analysing poor knowledge is part of the process suggested by the precautionary matrix.

• A single molecule is not a synthetically manufactured nanomaterial, but what about compounds of 10 or 100 molecules?

  With this and other borderline cases, it should be noted that when using the precautionary matrix one is not concerned with the exact definition of “nano”, but more about determining whether a possible nanospecific need for action exists. With this in mind, in case of doubt the use of the precautionary matrix for a giant molecule or agglomerates of single molecules is not wrong.

• Am I allowed to publish my results?

  Every user is free to publish his results. However, the use of the results to lead someone to believe in a possibly non-existent product safety (e.g. with a label “precautionary matrix class A”) is not welcomed. This does not correspond to the sense and the spirit of the precautionary matrix that, with its results, triggers deeper evaluations and should not itself be seen as a risk-assessment tool.

• Can consumers also use the precautionary matrix?

  In principle, anyone with sufficient data and understanding can use it. Indeed, the precautionary matrix has been designed for use by industry, trade and commerce. Following the evaluation, these users should assess the precautionary need and communicate appropriate protective measures.

• Can examples of completed precautionary matrices be obtained?

  Such examples are not available, as in the absence of the relevant context and the required introduction, they could be misunderstood and consequently have little value.

• Can the precautionary matrix also be completed by non-specialists?

  Non-specialists can only use the precautionary matrix with the assistance of specialists, as a certain basic knowledge is required in order to correctly assess the parameters. Likewise, contacts to experts are sometimes necessary in order to answer specific questions. The precautionary matrix has to have this scientific level, as in the absence of a scientific background it would be unable to produce any exploitable assertions. The same applies to the interpretation of completed precautionary matrices.

• Can the precautionary matrix be meaningfully used as a supplement to the safety data sheet?

  Yes. At present, there is no form for indicating nanospecific information. The important data required by the precautionary matrix can however be voluntarily indicated. Likewise, they can be requested together with the SDS from industry and commerce, when needed.

• Can the precautionary matrix be used for fine particulate matter?

  The precautionary matrix was not designed for use with fine particulate matter. However, here as well, the use of the matrix is not inappropriate as long as all required data are available.

• Has the practical suitability of the precautionary matrix been tested?

  The precautionary matrix has been tested for its practical suitability and revised accordingly in a trial phase, in which about 80 predominantly industrial users participated.

• How can the potential effect be evaluated in the absence of more detailed data?

  The assessment should be in comparison with already evaluated nanomaterials. An exemplary list of comparative materials is integrated in the Guidelines on the Precautionary Matrix.

• How shall primary manufacturers of nanomaterials answer the questions in the chapter “information”?

  These questions should be answered by the primary manufacturers of nanomaterials as follows. Question I1: Answer the question for non-nanoscale starting materials. Question I2: If no nanoscale starting materials are present, the answer for this parameter should be ‘yes’.

• How should mixtures of various nanomaterials be treated when the properties of the mixtures do not correspond to the sum of the individual properties of the nanomaterials, i.e. in the presence of synergistic effects?

  These “cocktail effects” are not taken into account by the precautionary matrix.

• In the context of the precautionary matrix, what are “synthetic nanomaterials”?

  The scope is described in the precautionary matrix by two approaches: The approach is based on the EU proposed definition 2022/C 229/01. In the second precautionary approach, primary particles up to an average particle size of 500 nm are also included.
  
  Nanostructured materials or fine particulate matter are excluded.

• In the environment shouldn’t particles that are larger than 500 nm also be considered as potentially environmentally relevant?

  No. Consideration to a maximum of up to 500 nm is applicable for all organisms. The uptake of larger particles is unlikely.

• In what languages is the precautionary matrix available?

  The precautionary matrix is available in German, French, Italian and English.

• Is it foreseen that the precautionary matrix will also be used outside Switzerland?

  Use of the precautionary matrix is not limited to Switzerland; a cross-border exchange of information and experience is, on the contrary, even explicitly welcomed and in the meantime has already occurred to a considerable extent.

• Is standard literature available to evaluate the precautionary matrix and select appropriate measures?

  No. The precautionary matrix and its evaluation must be examined on a case-by-case basis, i.e. based on specific issues. A list of standard literature sources for all these different cases is not available.

• Is the approach to nanomaterials in the environment really already relevant in regard to the quantities involved?

  Based on the market volumes, the input quantities can already be substantial and are increasing. In the context of an early envisage of potential future problems, the environment must without doubt be already included.

• Is the matrix based on scientific fundamentals?

  The parameters from the precautionary matrix are based on scientific considerations and intensive collaboration with pertinent experts. Should the state of scientific knowledge change then the parameters will also be adjusted accordingly.

• Is the use of the precautionary matrix binding to anything?

  The precautionary matrix is voluntary and is conceived only as a tool to provide support.

• Is there a basis for the quantitative limit of 500 kg/year for the environmental assessment?

  The limit is based on the following model consideration: On the basis of the TiO2 example, a PNEC of 1 μg/L is assumed. For an estimated use of 200 L water per day for each inhabitant of Switzerland (ca. 8 million), the annual volume is considered to be 500x109 L. This, together with the accepted PNEC, results in an annual limit of 500 kg, below which no effect occurs.
  
  This projection is very general and set at a high level for Switzerland as a whole. It should be pointed out that locally strongly different quantitative scenarios are possible. This is not however considered in the scope of the precautionary matrix. This projection will be re-evaluated and adapted according to new findings.

• Is there a list of possible measures for the precautionary matrix?

  The precautionary matrix is not used as a catalogue for possible measures, but rather for early assessments, namely when identifying handling requirements. The choice of measures is on a case-by-case basis and therefore does not appear in the context of the precautionary matrix.

• What are the key messages of the precautionary matrix?

  The precautionary matrix delivers the following key messages:
  
  The precautionary principle must and can be applied to synthetic nanomaterials
  Differentiation is necessary when considering the safety and risks (for employees, consumers and the environment)
  Not all nanomaterials are the same: Case-by-case differentiation of scenarios depending on the conditions of use or the surrounding conditions
  Voluntary measures by the responsible parties ("causers") are needed, but should be supported by non-bureaucratic assistance
  The precautionary matrix produces a rough preliminary decision and uniform basis for discussions of the need for more extensive investigations

• What are the target groups of the precautionary matrix?

  The target groups are stakeholders who are responsible for the safety of employees, consumers or the environment (industry, trade, commerce, government authorities, insurers, etc.)

• What does “nanospecific” mean?

  This term relates to properties of nanomaterials which result solely from their nanometric size, and which cannot be predicted from the properties of the bulk material.

• What does “potential exposure of humans” mean"?

  This does not mean the actual exposure, but the maximum possible exposure (worst case) of a human, taking into account the quantity and availability of the nanomaterials being handled.

• What does “potential exposure of humans” mean"?

  This does not mean the actual exposure, but the maximum possible exposure (worst case) of a human, taking into account the quantity and availability of the nanomaterials being handled.

• What does “uncertainty” mean?

  At some specific parameter entry points, the “input uncertainty” is requested. The evaluation of those uncertainties results in the probability with which the score exceeds the precautionary threshold.

• What does the question on coatings / functionalisation mean?

  For coated or functionalised nanomaterials it is important to decide whether these nanomaterials are stable or continue to exist in a different form and must therefore be treated in a further precautionary matrix.

• What does the score (point counts) mean and what is their purpose?

  The point counts used to classify the results of the matrix are based on a mathematical formula. They represent an arbitrary classification on a scale in order to facilitate the analysis of risk potentials and the comparison of different scenarios.

• What does the score (point counts) mean and what is their purpose?

  The point counts used to classify the results of the matrix are based on a mathematical formula. They represent an arbitrary classification on a scale in order to facilitate the analysis of risk potentials and the comparison of different scenarios.

• What does the stability of the nanomaterial mean exactly when considering the different possible environmental compartments? Are hours/days - weeks/months not too short?

  The stability for the environmental compartments has the same significance as for health. It is certainly sensible to use the same classification for the biotic part of the environment as for human health. For the abiotic environment the given time frames are if anything short; however, in the context of precaution this is advantageous.

• What exactly do “known” and “assessable” mean in the available information?

  Each user must decide this themselves. If there is uncertainty about whether something is known and can be evaluated, it is recommended to answer the questions as if there were no available knowledge.

• What exactly is the meaning of “environmental conditions”?

  The approach for assessing a certain scenario with the precautionary matrix is always based on limiting the actual generic conditions to a quite specific case. This means that also in the environment, the assessment of a specific nanomaterial must always be carried out in direct regard to its environmental conditions. These conditions depend on the chosen scenario: biotic or abiotic environment, different compartments, different environmental conditions, different types and amounts of nanomaterials.

• What is the best way of disposing of nanomaterials so that they do not end up in the environment?

  Information concerning the industrial and commercial waste can be found on the website Nanowaste (admin.ch)
  
  Contact FOEN, Sektion Industriechemikalien [e-mail]

• What is the legal status of the precautionary matrix?

  The matrix is legally non-binding and is used on a voluntary basis; no one has to justify the results. However, it can serve as a confirmation that planned processes or products have been examined in the context of prevention and existing scientific knowledge, and that applicable measures were introduced.

• What is the meaning of “information on the life cycle”?

  The available information relates to the knowledge of the manufactured, further processed or disposed nanomaterial. Any knowledge gaps are associated with greater precautionary need since they involve additional uncertainty.

• Who can I contact for questions and feedback?

  For all questions or comments concerning the precautionary matrix and its use, the following offices are at your disposal:
  
  
  Federal Office of Public Health (FOPH) [e-mail]
  Federal Office for the Environment (FOEN) [e-mail]
  Federal Office for Economic Affairs (SECO) [e-mail]
  
  
  Additional information can be found on the InfoNano website: http://www.infonano.ch
  
  Industry and trade associations are also willing to receive your questions and comments on the precautionary matrix.

• Why isn’t a matrix made available that is specifically tailored to the environment?

  We don’t want to remove the environmental part from the precautionary matrix, especially as the topic is closely linked with human health aspects.

• Will the precautionary matrix be updated on a regular basis?

  The matrix will be reviewed and adjusted as needed and after feedback has been received.

• Will the precautionary matrix take into consideration any misuse of products by workers or consumers?

  Misuse is not included in the precautionary matrix.