Safety of Engineered Nanomaterials

Norma Gonzalez; Linda Johnston

doi:10.1515/ci-2018-0415

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Safety of Engineered Nanomaterials

Norma Gonzalez and Linda Johnston

Published/Copyright: October 29, 2018

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From the journal Chemistry International Volume 40 Issue 4

Nanotechnology as an enabling technology offers potential solutions for scientific, industrial and commercial challenges through application specific nanoscale materials. As with all emerging technologies, the benefits of nanotechnologies must be weighed against potential health and environmental hazards associated with their development, use, and disposal. Although engineered nanomaterials are now used in many consumer products, the development of methods to evaluate the safe use and risk assessment of these materials has not kept pace with this rapid commercialization. The lack of adequate characterization of nanomaterials, as well as reproducible and validated methods for toxicological studies are major bottlenecks for the safe and sustainable use of nanomaterials.

An IUPAC Workshop on Safety of Engineered Nanomaterials (ENM) was held on 28-29 September 2017, in Queretaro, Mexico with support from the Chemistry and Human Health and Chemistry and Environment Divisions. Task group chairs Linda Johnston (National Research Council Canada) and Norma Gonzalez-Rojano (Centro Nacional de Metrologia (CENAM) Mexico) organized the workshop with assistance from task group members Esther Castro-Galvan and Yoshito Mitani (CENAM), Jesus Gonzalez-Hernandez (Centro de Ingenieria y Desarrollo Industrial, Mexico), Kevin Wilkinson (Université de Montréal, Canada) and Baoshan Xing (University of Massachusetts Amherst, USA).

This workshop brought together academic and government scientists to provide a critical overview of some of the key issues related to the safe and sustainable development and application of nanotechnology. The main objectives were to foster a greater awareness of the challenges; identify the infrastructure needed to evaluate physical, health, and environmental hazards (with an emphasis on the particular conditions in Mexico); exchange information on the status of regulatory guidelines for ENM; and summarize best practices for the safe use of ENM. Four themes were covered with presentations from 14 scientists and an extended discussion period after each theme and a student poster session.

Theme 1 focused on the detection and characterization of nanomaterials, both as produced and in complex environments. Presentations addressed challenges associated with quantifying surface functional groups, characterization of surface modified and encapsulated superparamagnetic nanoparticles (NP) used for nanomedicine, and applications of Surface Enhanced Raman Scattering for detection of Ag NP in environmental matrices. The discussion period highlighted the fact that it is usually not possible to identify a single “best” method for a given material/measurand combination and multiple methods are often required. Selection of a fit-for-purpose method requires consideration of method sensitivity, calibration and validation, information on the relevant concentrations, matrix and transformations of the ENM, and assessment of the level of uncertainty that is tolerable for the specific application. Read-across to minimize resources is desirable, although still challenging to implement.

Theme 2 provided an overview of transformations of ENM in the environment and in consumer products with presentations on ICP-MS methods for detecting NPs in water and studying their transformations, carbon nanotube release from consumer products, and an overview of a Mexican national system (SINANOTOX) for characterization and toxicology evaluation of ENM. The subsequent discussion focused on the key role of the medium and co-contaminants in understanding ENM transformations, the importance of the dynamics of transformation with time and changes in environment, and the need for standard methods for characterization in complex matrices under appropriate exposure scenarios. The detection limit for small NP in complex media is often a limitation. One approach to streamline measurements may be to use simple toxicity tests as a screening tool and then to follow up with detailed characterization if warranted. The SINANOTOX overview prompted discussion of the incentives for network participation, as well as the importance of ensuring adequate characterization of the ENM under the appropriate exposure scenario, employing validated protocols and moving beyond well-characterized materials such as silver and titanium dioxide.

Theme 3 on Nanotoxicology Methods and Gaps for EHS included presentations on approaches for improved dosimetry for ecotoxicology and the environment—with an emphasis on single particle ICP-MS measurements—followed by a discussion of the challenges in harmonizing in vitro methods for nanotoxicology that outlined lessons learned during development of an ISO standard for cell viability assays. Two presentations focused on the utility of in vitro assays in preclinical experimental models with examples drawn from bismuth NP and ultrafine particles as well as on developing assays and approaches for toxicokinetic data, including methods to mimic protein corona effects. The discussion period stressed the importance of using reference materials and developing standard protocols that are validated by interlaboratory comparisons, and evaluated the pros and cons of currently-used dosimetry metrics. The role of aging and latency effects was acknowledged as a gap that cannot readily be addressed by current in vitro methods.

Theme 4 addressed challenges for risk assessment, standardization and metrology with overviews of the risk assessment process from a NIOSH perspective, current OECD work on developing test guidelines for safety assessment of ENM, and a perspective on regulating nanomaterials in the EU. Two final presentations summarized current challenges for nanometrology and standards in Mexico with a focus on reference materials to address industrial needs and developing or adopting international standards that can be used for characterization and risk assessment throughout the life cycle of a product. The discussion period returned to the lack of standardized methods and protocols, particularly in complex environments and the need for more reference materials, especially in complex media. With respect to the public perception of risk, it was acknowledged that government, industry, and the consumer all have a role to play in ensuring safety of ENM. It was noted that toxicity of NMs is most likely to be an issue for materials that exhibit bulk toxicity or those that are is redox-active or have a fibre-like shape. Nevertheless, it is wise to employ the precautionary principle, remembering that any new technology will have risks and benefits.

For more information and comments, contact Task Group Chairs Linda Johnston <linda.johnston@nrc-cnrc.gc.ca> and Norma Gonzalez <ngonzale@cenam.mx>.

https://iupac.org/project/2016-045-2-700

Acknowledgements

The workshop organizers thank IUPAC Divisions VI and VII for their sponsorship of the workshop. We express our gratitude to all task group members and the following invited speakers whose contributions were key to the workshop success: Vicente Escamilla-Rivera, Cordula Hirsch, Peter Kearns, Jamie Lead, Gabriel Luna-Barcenas, Ruben Lazos-Martinez, Kirsten Rasmussen, Jaime Santoyo-Salazar, Aleks Stefaniak, Rafael Vazquez-Duhalt, Andrea de Vizcaya-Ruiz, Mark Wiesner. The following organizations provided financial or logistical support: Physikalisch-Technische Bundesanstalt of Germany, Mexican Society of Materials, Mexican Nanoscience and Nanotechnology Network, Center for Engineering and Industrial Development, Council of Science and Technology of Queretaro State, and Centro Nacional de Metrologia. Industrial exhibitors (Bruker, ISASA, Merck, Agilent Technologies, ThermoFisher Scientific and Perkin Elmer) also provided financial support.

Online erschienen: 2018-10-29

Erschienen im Druck: 2018-10-01

©2018 IUPAC & De Gruyter. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. For more information, please visit: http://creativecommons.org/licenses/by-nc-nd/4.0/

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https://doi.org/10.1515/ci-2018-0415