Quality evaluation of human and environmental toxicity studies performed with nanomaterials - the GUIDEnano approach

The European Union FP-7 project GUIDEnano developed a web-based guidance tool, which guides users to assess human and environmental risks of nanomaterial-enabled products throughout their life cycle. One of the aims in the GUIDEnano hazard assessment strategy is to derive safety limit values based on existing human toxicity and ecotoxicological studies. Clear criteria needed to be established to select studies that could be used for such purpose. In the present paper, we present an approach for a systematical and quantitative evaluation of the quality of environmental and human toxicity studies performed with nanomaterials. The approach builds upon previous initiatives and includes refinements to facilitate its application by users with limited toxicological expertise. It covers in vivo and in vitro human toxicity studies as well as ecotoxicological studies addressing the toxicity to all environmental compartments. A scoring system related to test design and reporting considerations was developed following the principles of the Klimisch score (K score). In addition, the approach includes a scoring system based on the physicochemical properties that have been characterized and reported for the nanomaterial, including properties characterized in the exposure medium (S score). These two scores (K and S) are combined to obtain an overall quality score (Q score) that can be used to select studies, to weight different studies, and/or to introduce uncertainty factors in the risk assessment process. During its development, the approach has been tested and refined with 137 peer-reviewed articles. The final quality assessment approach and the results of its evaluation are presented here.