Most cellphone companies design models especially for kids. But parents are usually the ones buying the phones. According to a July 2012 study, 56% of parents of children aged 8 to 12 have given their children a cellphone. The number goes up with age. The study just proves what many people already guessed: many kids, if not most, have their own cellphones. According to a recent survey, 12 is the magic number. It is the most common age for kids to get their first cellphone. But 13% of children aged 6 to 10 already have one. People who are for kids' using cellphones, including many parents, notice that cellphones help kids keep in touch with their friends and families. They believe that cellphones are an important tool in a dangerous situation. Kids can reach their parents at all times. And some people say having a cellphone helps teach kids to be responsible. Some cellphones designed for kids can be set to only work when parents approve  . What's the harm in that? But other people are worried about the health and safety effects of kids' cellphones. They believe that kids with cellphones will spend less time playing outside with friends, and that sending text messages or making phone calls while doing homework makes it difficult for kids to concentrate. They say that kids are spending too much time texting instead of talking to each other. "Our brains developed to communicate face to face," says Gary Small, a teacher at the UCLA School of Medicine, in California. "A lot of this is lost with texting." Another worry is cyber bullying  , which is on the rise as more kids use e-mail and text messages to communicate. And some experts are worried about possible health risks. They worry that energy waves produced by cellphones could be harmful to young people. To be safe, parents should not let them talk long on the phone. We can learn from the text that   _  .
there're cellphones specially designed for kids on the market kids aged 6 to 10 have more cellphones than kids at other ages kids who have cellphones have fewer friends than those who don't cellphones help kids improve their relationships with friends and families