Twin towers dust tied to some cancers, not others

Rescue and recovery workers exposed to airborne debris from the 2001 attack on the World Trade Center in New York are, overall, no more likely to develop cancer than unexposed people are, a new analysis of medical data shows. But a closer look at the records finds that three malignancies stand as exceptions: cancers of the thyroid and prostate and a blood cancer called multiple myeloma.

Meanwhile, bystanders and other people exposed to the dust have so far experienced no increased risk for any of 23 cancers, researchers report in the Dec. 19 Journal of the American Medical Association. The study was based on data from a registry that includes 55,000 New York residents exposed to the dust from the twin towers’ fall.

Why three cancers showed up in workers and the other 20 didn’t is unclear, says study coauthor Steven Stellman, an epidemiologist at the New York City Department of Health and Columbia University.

But any cancer rate increase raises the concern that exposures during the rescue and months-long cleanup operation may pose future risks, Stellman says.

“For most cancers, the latency period is quite long,” he says. “And this is very early in the process.”Other studies based on the medical registry have found an increased risk of certain diseases. Higher rates of asthma have emerged among workers and bystanders exposed to the dust from the twin towers (SN: 5/8/2010, p. 12). And Stellman says higher-than-average rates of heart problems, gastroesophageal reflux and post-traumatic stress disorder have also emerged.

People who worked amid the dust include first responders, cleanup crews, welders who cut up the tangled steel beams and barge and landfill workers who removed the rubble. By 2007 and 2008, this group showed a slightly increased risk for prostate cancer, a doubled risk of thyroid cancer and a nearly tripled risk of multiple myeloma when compared with the incidence rates in the general population of New York State.

The main carcinogens unleashed in the towers’ fall were asbestos, silica and polycyclic aromatic hydrocarbons. PAHs are gaseous compounds often produced by combustion — or incomplete combustion — of fuels. Stellman notes that the airplanes that hit each building had nearly full fuel tanks, and the collapses of the buildings also unleashed natural gas from their piping systems.

The registry receives federal funding and is supported by the National Institute of Occupational Safety and Health. “We’re encouraged to see new research and peer-reviewed studies” on the 9/11 rescue and recovery workers, says Fred Blosser, associate director for communications at NIOSH in Washington, D.C. “This kind of information is extremely useful for us in administering the health-monitoring and treatment programs.”