Guardian Unlimited ran a column today on the human cost of bad science and singled out Rachel Carson's research on DDTs. What is worth noting about her research, how she reported the findings, and the subsequent sweeping changes that were made based on her findings is a case study in the complexity of hoping to know what changes may come.
I do not believe scientists in general have any desire for their discoveries to cause bad things to happen. In fact I believe the opposite. Scientists, like everyone else, are trying to do good things. What may not be evident to many scientists is the inherent authority they wield by simply knowing things the rest of us cannot even guess at. If enough scientists say 'it's true' the rest of us believe and act on that truth we've been told.
A recent example of this is the discovery of a specific gas on Mars that some scientists adamantly state is proof there is life there. Have they found life? No. Is this gas only possible as a result of life? Scientists don't know. Here on the planet earth it's produced by living things, so taking a giant leap, science would have us believe that life on Mars is proven. Well, no its not. What IS proven is that this specific gas is on Mars.
Believing something is true effects everyone forever after the truth is accepted. Scientists should spend some time contemplating their ability to effect so many for so long.