Assessing the Environmental Risks of Nanomaterials: A Comparison of Risk Assessment Frameworks

Assessing the environmental risks of engineered nanomaterials (NM) is currently an intensely contested subject among scientists, organizations, governments, and policymakers. The shear number, variety, and market penetration of NM in consumer goods and other applications, including environmental remediation and sustainable nanotechnologies like solar cells, is increasing at an exponential pace and is expected to continue to grow in coming years and decades. At the same time, it is not yet clear whether traditional chemical risk assessment-based frameworks are suitable for these emerging NM due to a wide range of technical limitations. For instance, serious knowledge gaps remain within e.g. the detection of NM in the environment, developing adequate testing equipment and protocols, and toxicity endpoints (Grieger et al., 2009). In the past few years, many scientists and organizations have subsequently outlined research needs as well as some of the different modifications needed to adapt traditional chemical-based risk assessment frameworks to NM. Meanwhile others have also cited some perhaps deep and fundamental limitations of traditional risk assessment frameworks for NM, and have subsequently proposed the use of other risk assessment tools and frameworks (Grieger et al., 2009- submitted,). In the present work, we compare different environmental risk assessment and analysis frameworks proposed for NM, including multicriteria decision analysis, comprehensive environmental assessment, and Nano Risk Framework. These frameworks are assessed according to a number of criteria (10 in total) which have been previously proposed as important parameters to a successful (environmental) risk assessment for NM: comprehensiveness, overall utility, ensuring correct problem formulation, treatment of uncertainty, degree of precaution, inclusion of quantitative or qualitative data, inclusion of life-cycle perspective, iterative and/or adaptive, ensuring timely decision making, and degree of transparency. This analysis can ultimately assist scientists, government agencies, organizations, and other decisionmakers better decide on which risk assessment/analysis framework may be best suited for the specific risk decision at hand. Among other results, we find that while many of the assessed frameworks have their advantages along with limitations, most may require potentially lengthy decision-making processes for NM risk assessments, which is not favourable considering the current pace of NM development. We recommend the use of a multifaceted approach to assessing the environmental risks of NM, in which different risk assessment frameworks and/or tools may be used and combined for the particular question considered. Furthermore, we recommend the use of biomonitoring in some environmental ‘hot spots’ to serve as early warning detectors while the field of NM environmental risk assessment matures, as recommended in our previous work. Ultimately, this analysis may aid the advancement of environmental risk assessment of NM by comparing and documenting the applicability of different risk frameworks for NM in a transparent way and consequently ensuring that present and forthcoming environmental risk assessments and analyses include state of the art knowledge and considerations.