The Ontario English Catholic Teachers Association is raising concerns about the potential health and safety risks of WiFi Internet in schools and classrooms. The association released a paper this month that said WiFi should not be accessible in classrooms. Internet services should be wired through routers, which should be turned off when the Internet is not needed, the association said. The association represents 4,500 teachers in 1,400 schools across Ontario. "The safety of this technology has not thoroughly been researched and therefore the precautionary principle and prudent avoidance of exposure should be practiced," the report said. Health Canada says low levels of microwave radiation emitted by wireless devices are safe because they're below the threshold limits set out in its safety guidelines.