September 6th, The New York Times had an article, ”Inquiry Opens Into Effects of 9/11 Dust”, about one of the biggest health investigations ever, of 200,000 people who were exposed to the 9/11 dust:
The coarse alkaline dust and ash from the collapsing towers and subsequent fires produced coughs and asthma that for some people, especially those who worked directly in the rubble, have yet to go away even after two years, doctors say. A recently released study also found a slight but significant increase in the number of smaller babies born to pregnant women who were downtown on 9/11 compared with a group of pregnant women who were elsewhere at the time.
Most medical experts have said that they do not expect long-term health effects or higher cancer rates in the general population, primarily because for most people, exposure to the trade center’s pollutants was fairly brief. Most health research suggests that chronic long-term exposure is usually the way people get sick from pollution. But total certainty, the experts say, is not possible.
In 2002 there was some talk about the pollution containing mercury. The New York review reported that rescue workers at Ground Zero had mercury in their blood.
Professor Boyd Haley, an expert on the toxicity of mercury, wrote an open letter to The New York Daily (where the report was also published):
In the case of the firemen and policemen working at Ground Zero they would be exposed to mercury from two major sources. First, before the WTC tragedy the major mercury body burden of these individuals would have been from their dental amalgams if they had any. After September 11th, if they were at the Ground Zero site, they likely would have been exposed to additional mercury vapors generated from the heat and the components of the WTC that contained mercury released on damage.
See also this PDF at TalkInternational.Com.