Doctors at Winthrop University Hospital say they have definitive proof that first responders to the Sept. 11 attacks acquired a nerve disease from the neurotoxins they were exposed to at Ground Zero.

The disease known as neuropathy is not one of the conditions covered by the Zadroga Act - which provides Sept. 11 survivors with more than $3 billion for health care and more than $4 billion in victim compensation through 2090.

First responders with symptoms of neuropathy were sent to Winthrop for a diagnostic test called electromyography to confirm the diagnosis. A machine then tested the health of their nerves and muscles. It measures electrical activity after nerves are stimulated.

"Science is catching up to the 9/11 community and now the federal government has to catch up too. The onus is on them," says John Feal, of the Feal Good Foundation.

First responders say their petitions to include neuropathy in the Zadroga Act have been turned down twice. They say they will try again with federal health officials using the results of the new study.

"I was 100 percent sure last year...now, I'm 200 percent sure," says Dr. Marc Wilkenfeld, of Winthrop University Hospital. "I don't want to be here doing this again next year. We have very eloquent patients and I'm just hoping the government does the right thing."