A major pediatricians' group is urging families to limit the use of plastic food containers, cut down on processed meat during pregnancy and consume more whole fruits and vegetables rather than processed food. The American Academy of Pediatrics issued the guidelines. Certain chemicals that enter foods may interfere with the body's natural hormones in ways that may affect long-term growth and development. Among the chemicals that raised particular concern are nitrates and nitrites, which are used as preservatives, primarily in meat products; phthalates, which are used to make plastic packaging; and bisphenols, used in the lining of metal cans. Also of concern to the pediatricians are perfluoroalkyl chemicals, or PFCs, used in grease-proof paper and packaging, and perchlorates, an antistatic agent used in plastic packaging. "Avoiding canned food is a great way to reduce your bisphenol exposure in general, and avoiding packaged and processed food is a good way to avoid phthalates exposures," [guidelines author] Dr. Trasande said. He also suggested wrapping foods in wax paper in lieu of plastic wrap. The A.A.P. statement was particularly critical of a regulatory process by which the F.D.A. designates food additives "generally recognized as safe," citing a ... review of the program that determined "the F.D.A. is not able to ensure the safety of existing or new additives through this approval mechanism."