There are EPA regulations that relate to led in paint, see here. However, they fall into 3 categories: lead disclosure rules for buyers and renters of residential property, danger standards for residences, and training requirements for lead abatement and repair for child-occupied facilities. If this is an old school building and they haven't been scraping the paint, there is no violation of the law. In order for there to be a violation of the law, somebody had to do something to the pain, which violated the rules. §745.235 says that failure to comply is prohibited. There are very many things one is supposed to comply with (not having accredited trained workers and supervisors; improper certification; improper screening of materials being abated; and there are some specifics of abatement that are addressed, such as you cannot burn lead-based pain, you can't sand it off).
State laws may provide an alternative angle, via a negligence lawsuit. California has a special law, the Lead-Safe Schools Protection Act of 1992, which requires elementary schools and similar facilities to be "surveyed" to identify lead danger, and then notify parents. It is not clear whether one is likely to prevail in a negligence suit if a school does not renovate to remove the lead paint hazard, but one would have to show evidence of actual lead poisoning. As far as I know, no state requires schools to definitively abate lead paint in schools. However, I can imagine circumstances where the danger is egregious (the building is in serious need of repainting), and the school has simply neglected the health risk.