Toward the development of decision supporting tools that can be used for safe production and use of nanomaterials.

Although researchers have intentionally produced and used nanomaterials for more than a century, nanotechnology has made its mark in most areas of daily life in the past 20 years. Now thousands of products contain nanoparticles, nanofibers, or nanostructured parts. Because some chemical products have caused severe problems to human health and to the environment, we should consider the overall biological and toxicological effects of nanomaterials as we decide whether to use them in various products. We should also reflect on the mechanisms for making these decisions, which may greatly influence the development, production, and use of such products. The preselection of appropriate materials during the early product design state should allow industry and applied researchers to mitigate the risks of these new materials. However, currently the human and ecological risks of the applied nanomaterials during their life cycle are unknown. A large set of physicochemical characteristics can determine the potential human and environmental exposure to and hazards from nanomaterials. Thus, researchers will need many years to gather and analyze all the data to perform a comprehensive risk assessment for engineered nanomaterials and to develop a sound decision making process. The ideal risk assessment approach would include cost-effective screening processes to target resources toward the risks of greatest concern. The outcome of the risk assessment is only as good as the quality of the data used. Unfortunately, the actual review process of most journals that publish on nanotoxicology focuses on "mechanistic studies and results" rather than a toxicologically relevant outcome. For example, journals often do not include studies that show no effect as worthy of publication ("no-effect-studies" dilemma), which can lead to misleading interpretations of toxicological data for hazard identification. However, even with insufficient data sets, researchers can produce a preliminary comparable risk assessment ("approximate" risk assessment). Researchers have already performed risk-based evaluations of nanomaterials grounded on the comparison of exposure concentrations with no-effect levels (as required for chemical risk assessment), examining generic nanomaterials such as "nano-TiO₂" but not specific forms or modifications. Even though these data sets on hazard and exposure are incomplete, they already provide the basis to illustrate the current state of knowledge and uncertainties. Therefore industry and applied researchers can calculate the probability that an adverse effect might occur and begin to balance the benefits and potential risks of an innovation. Based on the increasing numbers of nanotoxicology publications and funding programs, this Account reviews the decision support approaches that already exist to safely implement engineered nanomaterials during an early phase of innovation.