Little information on very young workers and on the employment of special populations of youth is available. In large, national surveys, such as the Current Population Survey, it is difficult to get a sufficiently large sample of these populations for accurate analyses. Therefore, specially targeted studies are needed for particular subgroups of children and adolescents.

Little data exist on the illegal employment of children. Estimates based on violations of child labor laws often combine hour violations and hazardous-order violations. These estimates depend on known violations, which vary from year to year because of such factors as the number of inspectors available and the industries targeted for inspection. Furthermore, these estimates are unlikely to include children and adolescents employed in sweatshops or in other illegal activities.

The bureau's sampling methodology is designed to provide reliable estimates of employment at a national level, but the size of the sample often limits the detail with which reliable state-specific estimates can be made. Yet enforcement of child labor laws and occupational safety and health regulations is frequently done at the state level. State-specific estimates of employment in those industries and jobs where youths predominantly work are necessary not only for determining reliable rates of injury or illness, but also for targeting state-based inspections of compliance with child labor laws and sites for workplace-based educational efforts.

Many agencies, including the National Center for Health Statistics, the Bureau of Labor Statistics, the National Institute for Occupational Safety and Health, the National Center for Education Statistics, the Bureau of Justice Statistics, and the Occupational Safety