As summer begins and many teens either start new jobs or expand their hours on jobs they held during the school year, national labor officials are taking a hard look at the rules that govern the working conditions they face.

The U.S. Department of Labor is now calling for public opinion on the proposal (see box); if approved, it would be the most comprehensive revision of child-labor regulations in the past 30 years.

On the surface, it seems an auspicious undertaking and, beneath the surface, most of it is. The bulk of the 37-page update to the Fair Labor Standards Act would make working safer for young employees, ages 14 and up.

"It will safeguard the health and education of millions of working teens while at the same time allowing them to enjoy the benefits of a phased introduction to the workplace," Paul DeCamp, administrator of the department's Wage and Hour Division, said in a recent statement.

Let's break that statement down. The first part, about safeguards, refers to the proposed new bans on particularly hazardous activities, such as working at poultry slaughtering plants, riding on forklifts as passengers, fighting forest fires and loading and operating non-paper products balers and compactors. The proposal also would prohibit 14- and 15-year-olds from employment in youth peddling activities, also referred to as door-to-door sales.

This much seems cause for widespread agreement. It's even startling that so many years have gone by without these clarifications in place.

However, the part about the "phased introduction to the workplace" demands some extra scrutiny.

In particular, there's a section about "work-study" programs that, without careful federal oversight, could enable the erosion of limits to the hours that young people work while school is in session.

Oddly, this particular revision was inspired by an initiative launched by the Chicago-based Cristo Rey Network of 12 private schools. Academically motivated 14- and 15-year-olds are allowed to work up to eight hours a day on some school days, more than double what's now permitted for kids that age. The money helps them pay for tuition and, school officials say, helps prepare them for careers.

The program operated for a decade without realizing it was breaking the rules. The department issued a waiver; the current proposal would effectively make that waiver permanent by making such programs legal nationwide, in public as well as private schools.

Without disputing that Cristo Rey has helped students, exporting that success nationally would be no small feat. The feds would have to make sure students in the program could keep up with their studies without succumbing to exhaustion. Any parent of a working teen can testify just how precarious that balance is already.

The rule does impose requirements for a teacher coordinator and federal review of proposed school programs, but in today's overburdened schools, it's easy to imagine how much might slip through the cracks.

Even Cristo Rey officials have expressed doubts that their experiment could be replicated perfectly in public schools, where students aren't under pressure to make tuition payments.

There's already evidence to suggest teens don't need any more work piled on. According to a study this year funded by the National Institute of Occupational Safety and Health, many teens under 16 years old reported working after 7 p.m. on school nights, which is illegal, and roughly half reported using prohibited, hazardous equipment.

It may make more sense for the federal government to consider renewable exemptions for programs such as Cristo Rey on a case-by-case basis, rather than simply making its experiment the law of the land. Keeping sufficient time for study, rest and recreation should be sacrosanct among protections for young people at the threshold of the working world.