Is there a reason why you didn't quote the other part of the article?
"Various studies on health effects, including a 2002 study conducted by the University of Pittsburgh, have determined the average radiation dose to individuals near Three Mile Island at the time of the meltdown was about 1 millirem - much less than the average, annual, natural background dose for residents of the central Pennsylvania region. Twenty-five years later, there has been no significant rise in cancer deaths among residents living near the Three Mile Island site."
Also, that analysis of health statistics makes no claim of causality that I can find. There could be any number of other explanations, particularly when we know that radiation exposure is linked to cancer and there was no rise in the cancer rates. There's no explanation of how the time frame of two years came about, either, unless they can link it to the half-life of something or something like that.