The case study is organized around the comprehensive environmental assessment (CEA) framework, which structures available information pertaining to the product life cycle, environmental transport and fate, exposure-dose in receptors (i.e., humans, ecological populations, and the environment), and potential impacts in these receptors. The document does not draw conclusions about potential risks. Instead, it is intended to be used as part of a process to identify what is known and unknown about nano-Ag in a selected application. In turn, the external review draft of the document provided a starting point to identify and prioritize possible research directions to support future assessments of nanomaterials.
Engineered nanoscale materials (nanomaterials) have been described as having at least one dimension between 1 and 100 nm. They often have novel or unique properties that can arise from their small size. Like all technological developments, nanomaterials offer the potential for both benefits and risks. The assessment of such risks and benefits requires information, but given the nascent state of nanotechnology, much remains to be learned about the characteristics and effects of nanomaterials.
The document (“Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray") is intended to be used as part of a process to identify what is known and, more importantly, what is not yet known that could be of value in assessing the broad implications of certain nanomaterials. The complex properties of various nanomaterials make evaluating them in the abstract or with generalizations difficult if not impossible. Thus, this document focuses on a specific example of nano-Ag in disinfectant spray products.
The case study does not represent a completed or even a preliminary assessment of nano-Ag; rather, it and other, similar case studies support research planning efforts for nanomaterials. The document is organized around the comprehensive environmental assessment (CEA) framework, which structures available information pertaining to the product life cycle, transport, transformation and fate processes in environmental media, exposure-dose in receptors (i.e., humans, ecological populations, and the environment), and potential impacts in these receptors. When information is available, it also includes other direct and indirect ramifications of both primary and secondary substances or stressors associated with a nanomaterial.
The CEA approach is both a framework and a process; the external review draft of the document supported the latter aspect, which engaged stakeholders from diverse technical (e.g., toxicology, exposure science, atmospheric chemistry) and sector (e.g., industry, government, academia) backgrounds. Through a structured collective judgment method these expert stakeholders used the document to identify and prioritize research gaps that could inform future assessments and risk management efforts. Some of these research gaps pertain to nano-Ag in disinfectant spray; others to nano-Ag irrespective of its application, while still others may apply more widely to nanomaterials in general. These and other research gaps identified through similar applications of CEA to nanomaterials are intended to inform ongoing research planning for nanotechnology in the general scientific community as well as at the EPA.