The US Environmental Protection Agency (EPA) has requested public comments on a nanoscale silver case study. From the news item on Nanowerk,

This draft document … presents a case study of engineered nanoscale silver (nano-Ag), focusing on the specific example of nano-Ag as possibly used in disinfectant sprays. This case study is organized around a comprehensive environmental assessment (CEA) framework, which combines a product life-cycle perspective with the risk assessment paradigm. 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 and can be used as a starting point to identify and prioritize possible research directions to support future assessments of nanomaterials.

I’ve taken a look at the case study which is over 300 pages according to the PDF page counter. You can access the information about the call for comments  on the US Federal Register from here. By reading the document (at least the first few pages), I found out that this is the third such case study (from the case study, Note: The print version page numbers reflect the pagination style used in engineering documents, e.g., 1-10 is page 10 in section 1),

The focus of this document is a specific application of a selected nanomaterial: the use of engineered nanoscale silver (nano-Ag) as an agent in disinfectant spray products. The U.S. Environmental Protection Agency (EPA) recently completed similar “case studies” of nanoscale titanium dioxide (nano-TiO2) used for drinking water treatment and for topical sunscreen (U.S. EPA, 2009, 225004). Such case studies do not represent completed or even preliminary assessments; rather, they are intended as a starting point in a process to identify and prioritize possible research directions to support future assessments of nanomaterials.

Part of the rationale for focusing on a series of nanomaterial case studies is that such materials and applications can have highly varied and complex properties that make considering them in the abstract or in generalities quite difficult. Different materials and different applications of a given material could raise unique questions or issues as well as some issues that are common to various applications of a given nanomaterial or even to different nanomaterials. After several individual case studies have been examined, refining a strategy for nanomaterials research to support long-term assessment efforts should be possible. (p. 19 PDF, p. 1-1 in print)

…

Among the factors guiding the selection process at each stage was the potential for exposure of ecological receptors and human populations to the nanomaterial as a function of a particular application. This is not to say, however, that the selection of nano-Ag in disinfectant spray signifies a determination that it presents the greatest potential for exposure of all possible applications, or, for that matter, that any exposure actually occurs to such a product. Rather, the case study on nano-Ag in disinfectant spray and other case studies simply provide a means to focus thinking about the types of information that would be instructive in assessing the potential ecological and health implications of selected nanomaterials. (p. 20 PDF, p. 1-2 in print version)

I find this to be a very interesting approach and I can certainly see the value of using concrete examples rather than abstract concepts as a means of critiquing a future research approach. I imagine most of the comments will come from groups that can afford to have people read and analyze the case study.

The deadline for comments is Sept. 27, 2010.