Here's a great quote from the late management guru of all management gurus, Peter Drucker:
There is nothing so useless as doing efficiently that which should not be done at all.
We are obsessed with efficiency in the environmental movement, but efficiency is usually about being "less bad" rather than good. Sometimes we should just stop doing things rather than trying to do them efficiently. Nature is inefficient (how many seeds does an ash tree produce compared to the number of saplings that grow from them?), but it is sustainable and we're not.
So, what's the point in using a toxic material efficiently? On the other hand, energy efficiency makes renewable energy a more viable energy source. But don't assume efficient automatically means good.