IMM-rapport 1/2018 Nanotoxicology State-of-the-Art and Future Research Needs Bengt Fadeel, Editor Institutet för miljömedicin - IMM Nanotoxicology – State-of-the-Art and Future Research Needs Maria Albin Harri Alenius Kunal Bhattacharya Ulrika Carlander Bengt Fadeel Anda Gliga Roland Grafström Per Gustavsson Gunnar Johanson Anneli Julander Hanna Karlsson Pekka Kohonen Klara Midander Penny Nymark Lena Palmberg Swapna Upadhyay Editor: Bengt Fadeel IMM rapport nr. 1 – 2018 1 Preface The Institute of Environmental Medicine (IMM), a department at Karolinska Institutet, is an interdisciplinary research organization in the field of environmental medicine. At IMM, internationally recognized research in the fields of toxicology, environmental medicine, and epidemiology is conducted. IMM also provides science-based environmental risk assessments to governmental agencies in support of standards and regulations. Researchers at IMM are active in numerous projects funded by the European Commission, thus providing a wide network of international partners. In particular, IMM has played a leading role in the field of nanotoxicology, with participation in numerous projects in the Seventh Framework Programme, eg., FP7-NANOREG, and in Horizon 2020, as well as a number of national projects such as the MISTRA Environmental Nanosafety project, a collaboration between 5 Swedish universities. IMM researchers also participate in the 10-year GRAPHENE Flagship Project, focusing on effects on human health and the environment. The purpose of the current report is to provide an overview of the state-of- the-art of nanotoxicology, with particular emphasis on hazard assessment of nanomaterials for human health; effects on other species in the natural environment are not discussed. We discuss epidemiology of fine and ultrafine particles as a backdrop for the subsequent evaluation of engineered nanomaterials, and we reflect on the lessons learned from the first decade or more of nanosafety research, including the potential role of the so-called bio-corona on the surface of nanomaterials. Specifically, we address the four main areas of material characterization, exposure assessment, hazard assessment, and risk assessment of nanomaterials. We also discuss emerging systems toxicology approaches with which to understand the biological effects of nanomaterials. Finally, we identify knowledge gaps and future research needs in nanosafety. The report is a collaboration between scientists from several different units at IMM, and the work has been coordinated by prof. Bengt Fadeel, chair of the expert panel of the national nanosafety platform and head of the unit of molecular toxicology. 3 Table of Contents Preface………………………………………………………………………….3 Abbreviations…………………………………………………………………..7 Executive Summary……………………………………………………………9 Introduction……………………………………………………………………12 Production and Use of Engineered Nanomaterials…………...12 Hazard, Exposure, Risk: The Key Challenges………………..15 Epidemiology of Fine and Ultrafine Particles…………………..19 Physico-Chemical Properties and their Link to Toxicity………28 Characterization of the Bio-Corona and Role in Toxicity…….35 Exposure Assessment……………………………………………………….41 Occupational and Consumer Exposure to Nanomaterials…..41 Methods for Exposure Assessment and Particle Detection…47 Biodistribution…………………………………………………………………52 Uptake and Biodistribution of Nanomaterials………………….52 Physiologically Based Pharmacokinetic Modeling……………58 Hazard Assessment………………………………………………………….67 Pulmonary Toxicity of Nanomaterials………………………….68 Cardiovascular Toxicity of Nanomaterials……………………..76 Dermal Toxicity of Nanomaterials………………………………83 Developmental Toxicity of Nanomaterials……………………..91 Immunotoxicity of Nanomaterials………………………………94 Neurotoxicity of Nanomaterials………………………………..106 Gastro-Intestinal Effects of Nanomaterials…………………..113 Genotoxicity and Carcinogenicity of Nanomaterials………...120 Emerging Approaches……..……………………………………………….126 Advanced In Vitro and Ex Vivo Models……………………….126 High-Throughput Screening (HTS)…………………………...135 5 Systems Toxicology/Omics Approaches……………………..140 Structure-Activity Relationship Modeling…………………….146 Adverse Outcome Pathways (AOPs)…………………………152 Data Management: Supporting Nano-Risk Governance……158 Risk Assessment……………………………………………………………163 Limitations of Traditional Risk Assessment Approaches……163 Existing Risk Assessment Approaches for Nanomaterials…164 Conclusions and Future Research Needs………………………………..170 6 Abbreviations ALI, air-liquid interface MOA, mode-of-action AOP, adverse outcome pathway NIOSH, National Institute for Occupational Safety and Health BAL, bronchoalveolar lavage NOAAs, nano-objects and their agglomerates and aggregates BMD, benchmark dose OECD, Organization for Economic Co- CNT, carbon nanotube operation and Development ECHA, European Chemicals Agency OEL, occupational exposure limit ENM, engineered nanomaterial PBPK, physiologically based pharmacokinetic HTS, high-throughput screening PM, particulate matter IARC, International Agency for Research on Cancer QSAR, quantitative structure-activity relationship ISO, International Organization for Standardization REACH, Registration, Evaluation, Authorization and Restriction of Chemicals KE, key event STIS, short-term inhalation study KEMI, Swedish Chemicals Agency WHO, World Health Organization KET, key enabling technology WPMN, Working Party on MIE, molecular initiating event Manufactured Nanomaterials 7 Executive Summary Nanotechnology harnesses the unique properties of materials at the nanoscale. It is generally believed that nano-enabled technologies will have a pervasive impact on society, and engineered nanomaterials or ENMs are commonly hailed as one of the elements of a new industrial revolution. In light of the increasing production and use of ENMs across the globe, it is an essential priority to address the safety of this expanding class of materials for human health and the environment. Thus, while significant investments in nanosafety research have been made in recent years, the knowledge regarding interactions of ENMs with living systems needs to be translated into a risk management framework to support safe and sustainable development of existing and emerging nanotechnologies. The main challenges The recent report on safe handling of nanomaterials (SOU 2013:70) commissioned by the Swedish Ministry of Environment and Energy emphasized that measures are needed to exploit the opportunities that ENMs provide while minimizing potential risks to human health and the environment. It was also highlighted that safety research and innovation must be integrated. We fully support this view. Indeed, we believe that a national plan for nanotechnology research and innovation in which safety assessment is integrated at every step of the innovation process is an urgent goal. It is also important to consider the global nanosafety landscape in this regard. The EU nanosafety cluster published a strategic research agenda in 2013 and emphasized, amongst other things, the importance of ensuring that all the relevant stakeholders including both European and global organizations (eg., OECD) are involved in setting research priorities, to ensure that unnecessary duplication of efforts is avoided. The so-called communities of research, initiated by the European Commission and the US Government’s National Nanotechnology Initiative (NNI), represent one such example of international dialogue between scientists in the field of nanotechnology-related environmental, health, and safety research. However, the dialogue should encompass all stakeholders. Nanosafety cannot exist in a vacuum as there is no safety per se, only safety (or risk) in the context of innovation, production, and use. 9 The ProSafe White Paper published in 2017 as a joint effort of the FP7- NANOREG project and the Horizon2020 ProSafe project, highlighted that it remains difficult to come to conclusions regarding the risks of most nanomaterials and nano-enabled products, the main reason being that nanosafety research during the past decade has been predominantly “science-oriented” rather than “regulation-oriented”. We agree, to some extent, with the conclusions in the latter report. Hence, it is correct that considerable investments have been made in nanosafety research, not least in the EU, which has led to a better understanding of the biological interactions of ENMs. Moreover, we also note that the nanotoxicology community has been quick to adopt new and emerging approaches including high-throughput screening and omics-based systems toxicology tools. We agree that the exponential increase in the number of papers on nanotoxicology during the past decade does not automatically translate into useful tools for risk assessment and regulation of nanomaterials. This may be due, in part, to a communication gap – and further efforts are needed to bridge this communication gap between researchers and other stakeholders including regulatory agencies and industry in order to remedy the situation. The national platform, SweNanoSafe, represents an important and illustrative example in this regard. However, the current situation may also be due to an expectation gap – researchers hope to gain a better understanding of the principles that govern the biological interactions of nano-scale materials, while regulators require first and foremost a firm basis on which to determine risk to human health and the environment. These two goals are not mutually exclusive, but a dialogue is needed between the different stakeholders including