A New York non-profit group is urging parents to teach their children five simple rules to limit their exposure to cellphone radiation. "With a new school year upon us, the list of back-to-school supplies may include a new cellphone, typically one that has more power and can perform more functions," Patti Wood, executive director of Grassroots Environmental Education, says in a statement. "But emerging studies from all over the world are telling us to be extremely cautious about these wireless devices, especially where children are concerned." Wireless devices, transmitters and cellphone towers emit non-ionizing "radio frequency" or "microwave radiation," and a growing number of studies suggest prolonged exposure may cause health problems. Cellphone radiation is transmitted by the phone's antenna, which is embedded in the case of the phone in most current models. Virtually all manufacturers warn against holding the device next to the head, advising users to maintain a distance of about 1 inch, Wood says. Grassroots urges parents to teach their children to: -- Never hold a cellphone directly against your head. -- Use the speaker setting or a corded headset whenever possible. -- Switch sides frequently if you have to hold the phone near your head. -- Do not carry cellphones in pockets or anywhere else on your body. -- Use cellphones only for emergencies or quick check-ins.