CHICAGO (AP) _ An estimated 5.2 million American youngsters have some degree of hearing loss from such sources of noise as rock concerts, fireworks and lawn mowers, government research suggests.
In at least 250,000 of those young people, the problem may be moderate to profound.
The figures do not indicate what percentage have simply temporary, slightly muffled hearing or more severe, permanent damage.
But the researchers said the numbers are worrisome and they urged the use of ear plugs.
``Even when you have temporary damage for a few days such as muffled hearing, that can influence the child's ability to learn in the classroom,'' said Amanda Niskar, a nurse-epidemiologist at the Centers for Disease Control and Prevention, who led the study.
The findings, based on 5,249 participants in a nationally representative 1988-94 survey, appear in the July issue of the journal Pediatrics.
Participants were given hearing tests in which researchers looked for noise-induced hearing threshold shifts, or NITS. When participants' ability to hear certain decibels and pitches is graphed, NITS show up as notches.
When extrapolated to the rest of the nation, the findings indicate the presence of NITS in 12.5 percent of all Americans ages 6 to 19 _ or 5.2 million young people. That suggests at least a one-time exposure to excessive noise, Niskar said.
The findings also suggest that 4.9 percent _ or 250,000 young people _ have moderate to profound NITS. That suggests possibly permanent damage, Niskar said. But she said some of the others may have permanent damage, too.
Noise ``is an environmental and community problem for children,'' Niskar said. ``We need to push for children to wear hearing protection during noisy activities because NITS is entirely preventable.''