Researchers have called for more studies to be done on the levels and effects of a range of persistent organic pollutants, which do not degrade in the environment and can build up in human tissue.
Scientists took samples of dust from 20 nursery and primary classrooms in the West Midlands. These were then analysed for four chemicals commonly used in wall insulation, stain-proofing and flame-retarding fabrics, carpets and electronic equipment.
The research comes as concerns increase over the presence of dangerous materials in schools. Last week, 28-year-old Oldham resident Leigh Carlisle died of mesothelioma after long-term suspicions that she had contracted the cell-tissue cancer after being exposed to asbestos in her primary school in the 1980s.
The new report found that levels of HBCD, a chemical used in wall insulation that can disrupt the hormone system and cause cancer, were "significantly higher" than those from samples in offices and homes.
Levels of TBBP-A, a flame retardant, were similar to those found in dust from homes, but higher than samples taken from cars and offices. The chemical has been known to have toxic effects on the human body's hormone system.
Researchers also looked at levels of PFOS and PFOA, widely used in stain- proofing fabrics, although they were not able to compare classroom levels with offices, cars or homes. Both have potentially toxic effects on key body functions.
Researchers say classrooms could have seen a surge in chemical levels in the past 20 years as buildings became packed with whiteboards, projectors and computers.
Scientists say that while classroom levels for the chemicals studied were still within Government safety limits, the long-term effects of exposure are unknown.
There are also fears that children are being exposed to chemicals that are now banned in some countries.
Emma Goosey, one of the report's authors, said: "Our results show that classrooms contain significant levels of these compounds.
"We already know that children are more likely than adults to be exposed to persistent organic pollutants by consuming dust. We also know they are more susceptible to the effects of such chemicals.
"Classroom levels seem to be higher than in some other environments, probably because of the numbers of computers and firestain retardants used in furniture. It is important that we monitor levels of exposure across our lifespan."
Co-author Dr Stuart Harrad said: "Our initial work suggests exposure in classrooms is within safe levels for some chemicals, but may not be for others that are widely used. You are being exposed to a whole cocktail of these chemicals. So more work is needed to assess how exposure accumulates - these chemicals remain within the body."
The report, presented at the Dioxin 2008 conference in Birmingham last month, comes as teaching unions continue to highlight the problem of asbestos. An estimated 13,000 schools still contain the fire-retardant material, which has been linked to cancers in around 200 school workers.