#1 BAD polyethylene terephthalate, PET or PETE. Water bottles
#2 GOOD HDPE - detergent/oil containers
#3 BAD polyvinyl chloride/PVC - Pipes
#4 GOOD low-density polyethylene, LDPE - Grocery bags
#5 GOOD polypropylene, PP - Plastic cups/food containers
#6 BAD polystyrene/PS (styrofoam)
#7 BAD Lexan and others unclassified
Source
For more properties on plastics see this...
