"The most important thing the government does is protect the public," Mueller said. "That's why people have governments. So the most responsible manner of doing that is to go through this kind of analysis to see whether an additional expenditure will reduce the risk enough to justify its cost. That's sort of hard-nosed stuff, but that's the way it has to be done. It's done in medicine all the time. They give vaccinations. They know some of those vaccinations are going to kill people, a very small percentage. But they have to look at that, and they talk to patients saying there's a very small chance this could really do damage to you, but mostly it's going to do good things. And overall the people are willing to accept those kinds of risks."