In the name of science, Z Recommends set up a series of sippy cup field tests, which we think is pure genius. Using a 2.5 year old junior researcher to conduct the study, each cup, all of which are made of either metal or non-polycarbonate plastic, all known to be free of Bisphenol-A or other potentially toxic plasticizers. was evaluated over a 2 week period. Their field notes are extensive! Each sippy cup was evaluated based on materials used, design, dishwasher safety, and price. Be sure to check out the results and observations! If you are worried about plastics, be sure to also check out their del.icio.us list of links regarding plastics safety. Have you field tested any of these sippy cups? Got a favorite, or is there one you would recommend to other parents? Let us know via the comments!