A new telephone study of 928 teen workers finds that many of them in the retail and service industries report working long hours and using dangerous equipment despite federal child-labor laws prohibiting these practices.

The University of North Carolina at Chapel Hill researchers found that 52 percent of males under 18 and 43 percent of females under 18 said they use equipment like box crushers and dough mixers, or serve and sell alcohol where it is consumed, both violations of the law. A third of the young workers received no safety training.

Researchers also found that 37 percent of working teens under 16 reported being on the job after 7 p.m. on a school night, another violation.

Concluded study author Carol Runyan: "Though there are benefits to work, not enough attention has been paid to safety." The study was published in the March 1 issue of the journal Pediatrics.