An increasing number of engineered nanomaterials (ENMs) are entering the market in everyday products spanning from healthcare and leisure to electronics, cosmetics, energy, agriculture, food and transport.
While for chemicals, there are established regulatory frameworks dealing with the risk for the consumers, workers and the environment, this is not the case for nanomaterials. The cause is precisely the reason for ENM use – the properties of matter at the nanoscale change and become dependent on the feature or particle size.
Our understanding on how such nano-systems react with biological matter, such as cells and tissues, is far from complete, and this brings about an increasing level of uncertainty in the research and development process.
It has become increasingly clear that harmful properties of nanoforms often do not correlate with the toxicological profile of the bulk materials. One of the challenges here is the identification of the best metric for toxicological assessment. A related challenge is how a nanomaterial can be defined as there are several different definitions internationally.
In Europe, the concept of safe-by-design was established to help the development of nanomaterials, minimising the risk at every stage of the research and development process in order to achieve long-term commercial potential and consumer acceptance. At the heart of safe-by-design lies the concept of substituting the question ‘Is the material safe?’ with ‘Can we engineer the nanoform to be safe?’.
Identifying the hotspots of nano-risk
An holistic view of the nano-hazard and the related process nano-risk is crucial for successful integration of nanosafety aspects into the overall risk management methodology. Material properties, health effects, potential of release, and occupational exposure are principal aspects for successful risk mitigation (Fig. 1). Traditional chemical risk assessment tools are based on the quantitative dose-response relationship, which is augmented by setting a threshold defining the no-effect levels or occupational exposure limit (OEL). It is applicable in cases when sufficient toxicological and occupational exposure data are available (Fig. 2). However, this is not the case for the majority of nanomaterials and nano-risk.
Additional challenges are the size and shape-dependence of the toxic effects, which can be substantially modified by applied functionalisations or the interactions with the environment in the body. Therefore, the current expert opinion tends to agree that conventional risk assessment tools have limited applicability to nanomaterials.
At present there is no regulatory agreement on OELs for nanomaterials, which slows down industrial acceptance of such materials and hampers consumer confidence.
These identified gaps in understanding promote the view that the most promising approaches for management of nano-related risk must be based on grouping principles. This brings the field’s attention to various risks, nano-risk and control-banding tools.
Efforts in the direction of grouping of nanomaterials and read-across missing properties of nanoforms are encouraged by stakeholders such as the nanotechnology industry, national regulators, and international bodies, for example the Organisation for Economic Co-operation and Development (OECD).
There is a recent international standard dealing with nanosafety and nano-risk in occupational settings: ISO Technical Standard ISO/TS 12901-2:2014 ‘Nanotechnologies – Occupational risk management applied to engineered nanomaterials’. The main assumption of the standard is that the risk is measured in a relative way! This assures the genericity of the approach, as the hazard can be compared to reference materials and interactions, for example considering the inhalational exposure route.
The NanoStreeM project
Identifying methodologies for risk assessment and governance of such situations is part of the work going on in the Horizon 2020 project NanoStreeM,1 which targets the semiconductor industry. The consortium – a mix of industrial, research, and academic partners – is working together to develop guidelines for the sampling, health monitoring, wastewater characterisation, risk assessment methodology, and training of employees in the semiconductor sector with respect to nanomaterials (Fig. 3).
The NanoStreeM consortium has taken up the challenge of defining a roadmap of safety of nanomaterials in nanoelectronics, in which we identify the existing gaps in our knowledge and formulate a number of recommendations for their mitigation.
Why the semiconductor industry?
The semiconductor industry can be presented as a use case on how potential occupational and environmental risks brought about by such products are governed. Specifics of this industry, which make it interesting, are several:
- The nanoelectronics industry plays a key role in solving Europe’s societal challenges; its products and innovations are essential in all market segments where Europe is a recognised global leader; and the intensity of its industrial research and innovation is among the highest in the world. Industrial production accounts for 16% of Europe’s GDP and remains a key driver for innovation, productivity, growth, and job creation; and
- Nanoelectronics enjoys a very fast innovation cycle governed by Moore’s law. This brings about a variety of new materials and combinations into production, while some of them are in nanoform.
Nanoelectronics relies on multiple semiconductor processes resulting in pattering of macroscopic objects (silicon wafers) on the nanoscale. Semiconductor mass manufacturing employs top-down high-precision approaches offering nanometre-resolution of detail. Engineered nanomaterials are used in several processing steps. On the other hand, nanomaterials can be produced as side products of several generic processes.
The road ahead
Although the project has still one more year to run, several key findings have come in view:
- Nanomaterials are regulated by REACH and CLP in European Union countries. However, the required information regarding nanomaterials is not readily available for the safety professional. The standard safety data sheets for chemical products do not contain information about eventual presence of nanoforms and their characteristics;
- We have established a necessity for grouping of nanomaterials in similarity groups (i.e. such as hazard bands or classes). The health and safety assessment can be empowered by the availability of standards such as ISO/TS 12901-2:2014. The standard defines five nano-hazard groups which combine with four exposure bands. This is constrained by five control bands which identify measures to be implemented in order to reduce the risk to the personnel; and
- There is a growing body of data related to potential exposure scenarios both to the worker and the environment for nanomaterials currently in use in semiconductor manufacturing. However, given the strong research culture within this industry, attention needs to be afforded to those nanomaterials that are of a strategic importance to the sector in order to ensure their appropriate environmental and safety management.
To date a total of 32 risk assessment tools have been identified under quantitative and qualitative methodologies. Based on the collected potential exposure scenarios a detailed recommendation focusing on a key group of four risk assessment tools has been developed.
At present, the efforts of the NanoStreeM project are focused on evaluation of the proposed risk governance paradigms, staring from the ISO standard. We have prioritised several common to the semiconductor industry scenarios. The consortium industrial partners evaluate state-of-the-art risk assessment tools and compare them to available emission measurements.
To address challenges in nanomaterial risk assessments, the Horizon 2020 projects NanoStreeM and caLIBRAate, with the support of the Royal Belgian Academy for Arts and Sciences, Flanders, have organised a joint workshop entitled ‘Governance of emerging nano-risk in the semiconductor industry’.
The nano-risk workshop will take place in Brussels on 26 April 2018. It will bring together regulators, policymakers, the growing risk governance community for nanomaterials, and the industries that will apply and build business based on the nano-risk governance methods.
The meeting will present how and where nanomaterials are used in the semiconductor industry based on the findings of the NanoStreeM project. The project caLIBRAte will present nanomaterials risk governance frameworks which could be applied within the semi-conductor industry. The workshop will conclude with a panel discussion on the steps necessary to further enable use of nanomaterials throughout the industry and appropriately govern the emergent nano-risks.
The meeting outcome will identify the challenges and regulatory issues in the semiconductor industry and how risk governance tools for nanomaterials can support effective business operation.
More information is available on the Nanostreem event webpage.
Nanomaterials are broadly defined as those materials that have a certain percentage of particles at the nanoscale, between one and 100 nanometres. For example, the EC recommendation stipulates that 50% primary of the particles must reside in this range, except in specific cases to be further identified. While the size cut-off used in the definitions is somewhat arbitrary, it nevertheless conveys the important fact that properties of materials with nanoscale features (e.g. nanoforms) can substantially differ from the properties of ‘macro’ materials in bulk.
Nanoforms can have desirable characteristics such as increased strength of the material, modified chemical reactivity, or electrical properties. These features offer possibilities for new applications in a broad range of sectors: for example, in medicine (e.g. detection of genetic sequences using DNA-tagged gold nanoparticles); environment (e.g. wastewater treatment with carbon nanotube filters); or energy production (e.g. solar cells using silicon nanocrystals).
At the same time, the use of manufactured nanomaterials in a number of commercial applications raises questions about potential unintended risks to humans and the environment – for it is known that particles of nanometre size can get deposited in the lungs, pass easily through alveoli, or even get dispersed in the body.
The NanoStreeM project (Nanomaterials: strategies for safety assessments in advanced integrated circuits manufacturing) receives funding from the European Union’s Horizon 2020 Research and Innovation Programme under Grant Agreement No. 688794