The NISE Net has a forum called "Risks, Benefits, and Who Decides?"  but maybe the question should be "How do they decide?"
Dietram Scheufele, a Professor of Life Sciences Communication at the University of Wisconsin is one of the authors of an article on how leading U.S. nanoscientists form policy stances about nanotechnology.  He summarized the article really well in his blog, nanopublic , saying in the end,
"Policy makers need to realize that when they ask scientists to give them advice about inconclusive findings, they will get both their professional judgment and their personal views."
Scanning through the article, I was intrigued by the authors' finding that there were differences in how supportive scientists were of regulation of nanotechnology based on gender and discipline. I'm looking forward to reading it more carefully, and I'm interested in whether these findings have implications for educators working with researchers.