Cancer from what? This sounds like such BS.
“WTC epidemiologists say studies show that 9/11 workers have gotten certain cancers at a significantly higher rate than expected in the normal population — prostate, thyroid, leukemia and multiple myeloma.”
They do not mention the actual increase in the rate, or whether it could simply be attributed to higher detection levels due to increased testing.
Most likely asbestos, as there were tons of it used in the lower floors of the WTC.