Assessing the comparative environmental impact of products and materials using single attribute characteristics, such as recycled content, point of extraction, and VOC content, is like trying to figure out how many miles to the gallon a car gets based on color. It is impossible to do in any really meaningful way. There is so much more that needs to be considered to really know what product or material is less harmful to the environment that another. Energy used for extraction of raw ingredients, manufacturing and transport; in-service life expectancy; maintenance requirements; etc.
The latest and greatest draft version of LEED has been struggling mightily with this in moving toward a more comprehensive appraisal of the Materials and Resources credits, the sixth public comment period having just concluded. Although the USGBC insists that this will be the last public comment period before v4 goes to ballot, public comments would seem to indicate otherwise. Here is a small example of some of the most recent comments: