Science Digest

Science Digest: Health Issues After Sept. 11 Attacks Studied

Exposure to dust at the World Trade Center increased the chance of asthma.
Exposure to dust at the World Trade Center increased the chance of asthma. (By Alex Fuchs -- Associated Press)
Monday, August 17, 2009

Asthma, Stress Found Years After 9/11 Attacks

Office workers, rescuers and others directly exposed to the Sept. 11, 2001, World Trade Center attacks reported new cases of asthma and symptoms of post-traumatic stress five to six years later, according to a study in the Aug. 5 issue of the Journal of the American Medical Association. Exposure to dust clouds, especially among rescuers who worked atop the pile of rubble, increased the likelihood of developing asthma.

The data come from the World Trade Center Health Registry, which tracks 71,437 of the approximately 409,000 adults who personally witnessed the attacks. A total of 46,322 people in four categories -- rescue workers, lower Manhattan residents, office workers and passers-by -- responded to surveys in 2006 and 2007 about their health.

Slightly more than 10 percent of respondents had developed asthma; 39 percent of those reported intense dust cloud exposure.

The prevalence of post-traumatic stress symptoms, which indicate probable post-traumatic stress disorder, has increased from 14.3 percent, when the researchers first interviewed the subjects in 2003 and 2004, to 19 percent in this new wave of surveys. Factors that increased the likelihood of post-traumatic stress included witnessing people jumping from the towers, being injured and knowing someone who died in the attack. Researchers asked the subjects about symptoms such as flashbacks and emotional numbness.

"There is some evidence, from other studies on veterans, that sometimes people develop PTS symptoms some years later after their trauma," said the study's co-author, Robert M. Brackbill of the Centers for Disease Control and Prevention. "We may be seeing that in this same population."

Researchers used this data to estimate that 25,500 adults have post-attack asthma and 61,000 have symptoms of post-traumatic stress. The third wave of health surveys will go out next year, Brackbill said.

-- Rachel Saslow

Focus on Black Holes

How close can matter get to a black hole before being irretrievably captured? Astrophysicists may soon be able to discover the answer with a new NASA mission scheduled to launch in 2014.

The Gravity and Extreme Magnetism Small Explorer (GEMS), a satellite being developed as part of NASA's "Small Explorer (SMEX) series of cost-efficient and highly productive space-science satellites," will be "the first to systematically measure the polarization of cosmic X-ray sources," according to a press release. Some examples are black holes and neutron stars.

"Predictions say how close matter can get [to a black hole] and they say that the photons emitted there are bent by the black hole and that it changes their polarization," said Jean Swank, an astrophysicist and the GEMS principal investigator. "GEMS is going to measure the changes in polarization that is predicted."

The GEMS satellite will be launched into low orbit, about 500 kilometers from Earth, just a little further than the space shuttle, said astrophysicist Keith Jahoda, GEMS deputy principal investigator. But the sources from which it will collect data will be astronomical distances away, he said.

Jahoda said the closest source will be a black hole 1,000 light years from Earth. The farthest sources will be stellar black holes, which are 100 million times the sun's mass and 10 million light years away, he said.

Jahoda said the information gathered will help astrophysicists gain more understanding about how the universe evolved. "The story of how we got from the Big Bang to here depends on understanding the evolution of the universe in all conditions," Jahoda said.

"It's also part of the story of predicting what's going to happen in the future," Swank said. "The stars that we see now, some of them will collapse into black holes and our galaxy may collapse into a super massive black hole," she said.

But that won't happen for billions of years, she added.

-- Ibby Caputo

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