Cell culture.

• Author: Lyall, Sarah
• Position: International

A newspaper in Helsinki, Finland, recently published a cartoon of a baby with a cell phone, notifying his parents that his diaper needed changing. But it's barely a joke. Helsinki is home to Nokia, the cell-phone maker. It's one of the most cell-happy cities in the world: An estimated 92 percent of its households have at least one cell phone. And the kids start young.

"A relatively normal age to get a mobile phone is now 7," says Jan Virkki, marketing manager for a cell-phone retailer. Among the second graders at the Kulosaari Elementary School, the most fashionable object of desire this year is not a Barbie or a Power Ranger. It is a Nokia cell phone accessorized with a personal logo on the screen.

"One of the first things we discuss when school starts is the policy on mobile phones," says Tiia Korppi, a teacher. Among...