No Subject

Used tires are being recycled in many ways-road beds, building materials for
houses, fuels for kilns, erosion stablization, shredding to improve turf field

 But---What about food production? Creating raised beds out of used tires and
 growing vegetable crops.

 What are any possible problems with this (e.g., heavy metals, xenobiotics)?
 Current thought is that tires are stable, with the only problems being in
 rodent and insect populations increasing.  any ideas??