With sales of its Lap-Band weight-loss device declining, Allergan Inc. has its eyes on a new set of potential customers -- overweight teenagers. The Irvine company has asked the Food and Drug Administration to approve Lap-Band surgeries for adolescents as young as 14, and is conducting clinical trials on teenage patients, said Cathy Taylor, a company spokeswoman. Allergan says the device -- a silicon ring fitted around the stomach to reduce food intake -- has proved a safe and effective way for obese adults to shed pounds. With an estimated one-third of U.S. children now overweight, the benefits should be extended to teenagers, Taylor said. "We identified a significant need with this patient population in terms of the increasing rate of obesity in younger populations," Taylor said. "Obesity, if left untreated, correlates to life-threatening diseases." But many doctors and health experts are concerned that there are not enough data about the Lap-Band's long-term safety and effectiveness, something that would be particularly relevant when considering the device for children.