You might want to check out a medical library (for you, Van, that
would mean the Med Library at IUPUI / IU Med School in Indianapolis, just
around the corner from the Zoo) under toxicology. The organic chemistry
involved can be complex, and the reading at a graduate level. If you are
concerned about deleterious effects, I think a large part of that comes from
sloppy handling and over-use, rather than run-off or seepage.
You know I hate to ask, but are friends electric? Mine's broken down, and now
I've no-one to love - Gary Numan Pete Womack at kaweiss at indiana.edu