The danger to students is uncertain, and EPA does not know for sure how many schools could be affected. But the agency is telling schools that they should test old caulk and remove it if PCBs turn up in significant amounts.
EPA Administrator Lisa Jackson said PCBs remain in schools and many other buildings built before the chemicals were banned in the late 1970s.
"We're concerned about the potential risks associated with exposure to these PCBs, and we're recommending practical, common sense steps to reduce this exposure as we improve our understanding of the science," Jackson said in a news release issued Friday.
The agency said it would conduct new research into the link between PCBs in caulk and in the air, which it said is not well understood. Studies in European countries have shown that PCBs in caulk contribute to dust and air inside schools and other buildings.
EPA now recommends testing for PCBs in peeling, brittle, cracking or deteriorating caulk in schools and other buildings that were built or renovated between 1950 and 1978. The caulk should be removed if PCBs are found at significant levels, the agency said. The agency also will conduct its own tests on PCBs in schools.
The law already requires that building owners remove caulk if they discover very high levels of PCBs. But proper removal is very expensive.
"It's a huge disincentive for building owners," said Robert Herrick of Harvard's School of Public Health. "If you look for it and find it, you have to report it to the EPA and remove it, so why would you look for it in the first place?"
He said Berkshire Community College in Massachusetts saw an approximately $2 million project for window replacement and renovation increase to $5 million after engineers tested caulk and found PCBs.
Earlier this month, a Bronx, N.Y., mother sued New York City over PCBs in caulk at her daughter's public school.
New York City schools spokeswoman Ann Forte declined to comment on the lawsuit, but said the school system is "engaged in positive and productive discussions with EPA to develop and agree on a plan to address PCBs in New York City schools."
Federal officials said the issue was serious but should not be cause for alarm. The agency recommended these steps for buildings of that age:
-Don't sweep with dry brooms or use dusters in places near caulk that might contain PCBs, and clean frequently with a wet or damp cloth.
-Clean air ducts, improve ventilation by opening windows and use exhaust fans and vacuums with high-efficiency air filters.
-Wash hands with soap and water often, especially before eating or drinking, and wash children's toys often.
The agency also set up a PCBs in caulk hot line, 1-888-835-5372, and Web site, www.epa.gov/pcbsincaulk/.
PCBs, known formally as polychlorinated biphenyls, are chemicals that were widely used in construction and electrical materials - they made caulk more flexible - before they were banned 30 years ago. PCBs can hurt the immune, reproductive, nervous and endocrine systems and can cause cancer if they build up in the body over long periods of time.
Hundreds of the 80,000 public school buildings across the country were built between 1950 and 1978, though it is difficult to say exactly how many.
A decade-old Education Department report said the average building was 40 years old, and the Rebuild America's Schools coalition says that two-thirds of schools have an environmental problem such as the presence of cancer-causing asbestos or radon gas, lead in water and paint, leaking underground storage tanks or cancer-causing radon gas.