Federal law says 16-year-olds may not use blowtorches to burn hair from animal carcasses in slaughterhouses. Yet they are allowed to work as "headskinners.''

These rules, and thousands more, are found in the 1938 Fair Labor Standards Act, a complex federal law with a simple goal: Keep kids safe and in school.

After almost 60 years of revision, federal child labor laws address everything from the time the sun comes up to the weight of a tractor. The fundamentals, however, still say:

Persons 18 and older may do any job for unlimited hours.

Sixteen- and 17-year-olds may perform any job not declared too hazardous for them by the U.S. Secretary of Labor.

Fourteen- and 15-year-olds may work in non-hazardous jobs outside school hours.

In non-agricultural jobs, they may work no more than 3 hours on a school day, 18 hours in a school week, 8 hours on a non-school day, or 40 hours in a non-school week. They must not work later than 7 p.m. on school nights or 9 p.m. on other nights.

Twelve- and 13-year-olds are barred from most jobs, but may work outside school hours on their parents' farms, or on other farms with parental consent.

Children under 12 are barred from nearly all employment but may work on their parents farms. They also may work on small farms that are exempt from federal minimum wage rules, as long as they have written parental consent.

Seventeen types of jobs are considered "hazardous'' for 16- and 17-year-olds, including work involving explosives, driving cars and trucks, mining, logging and slaughtering. There more such restrictions for younger children.

There are four other exempted jobs in which children may work with little restriction: acting, wreath-making, delivering newspapers, and sports-related jobs such as baseball batboys.

Federal child labor law applies only to employers who are engaged in interstate commerce. Employers whose products never leave the state, and whose sales come to less than $500,000 annually, are exempt.

Companies involved in interstate commerce can also be held responsible under federal "hot goods'' statutes, which are part of the Fair Labor Standards Act. For example, a tomato harvested by an underage child can taint a batch of pasta sauce all the way to the manufacturer or retailer. "Hot" goods shipped across state lines can be seized with a court order.

Employers not covered by federal law remain subject to state child labor laws. State laws vary widely, as do state enforcement efforts.

Oregon law, for example, permits children as young as 9 to pick berries and beans. Hawaii law says 10-year-olds may harvest coffee. Idaho and Maryland say they have no one assigned to enforce child labor laws. California and New York have teams of labor investigators searching for child labor violations.