"To imagine that there is strong evidence about any cancer resulting from 9/11 is naive in the extreme," said Donald Berry, a biostatistics professor at the University of Texas MD Anderson Cancer Center in Houston.
Yet this month, John Howard, who heads the federal agency that researches workplace illnesses, added scores of common and rare cancers to a list that had previously had just 12 ailments caused by dust exposure.
Lung, skin, breast and thyroid cancer were among those added; of the most common cancer types, only prostate cancer was excluded.
Howard declined interview requests. His decision, based on an advisory panel's recommendation, will go through a public comment period and more review before it's final.
Several factors about the decision by the National Institute for Occupational Safety and Health raised eyebrows in the scientific community:
Only a few of the 17 people on the advisory panel are experts at tracking cancer and weighing causal risks; they were outnumbered by occupational physicians and advocates for Sept. 11 rescue and cleanup workers.
Exposure to a cancer-causing agent doesn't necessarily mean someone will develop cancer. And if they do, conventional medical wisdom says it generally takes decades. But the panel agreed to cover those diagnosed with cancer within just a few years of the disaster.
The panel members favored adding cancers if there was any argument to include them. They added thyroid cancer because a study found a higher-than-expected number of cases in firefighters who responded to 9/11, even though thyroid cancer is generally linked to genetics or high doses of radiation.
Even lawyers for the first responders were stunned: They had expected to see only certain blood and respiratory cancers put on the list.
After Sept. 11, the government established the Victim Compensation Fund, which paid out about $7 billion for the nearly 3,000 deaths from the attacks and for injuries, including some rescuers with lung problems.
In late 2010, Congress set up two programs for anyone exposed to the rubble, smoke and dust at ground zero: rescue and cleanup workers and others who worked or lived in the area. Cancer was initially excluded, but Congress ordered periodic reviews based on the latest evidence.
One $1.55 billion program is for treatment for any illness found to be related to ground zero. The second, $2.78 billion fund is to compensate people who suffered economic losses or a diminished quality of life because of their illness.