The remainder consisted of more than 2,500 contaminants,[5] more specifically: 50% non-fibrous material and construction debris; 40% glass and other fibers; 9.2% cellulose; and 0.8% of the extremely toxic carcinogen asbestos, as well as detectable amounts of[6] lead and mercury. There were also unprecedented levels of dioxins and PAHs from the fires which burned for three months.[7] Many of the dispersed substances (asbestos, crystalline silica, lead, cadmium, polycyclic aromatic hydrocarbons) are carcinogenic; other substances can trigger kidney, heart, liver and nervous system deterioration. This was well known by the EPA at the time of collapse.[5] A case report funded by the National Institute for Occupational Safety and Health (NIOSH) and performed by Mount Sinai School of Medicine observed carbon nanotubes in dust samples and in the lungs of several 9/11 responders.[8] The understanding of the smoke and dust in the air was not fully understood at the time; the World Trade Center Health Program's Dr. Michael Crane touched upon this issue in an interview with Newsweek stating:[9]