NEW YORK – An autopsy linking the death of a police officer to dust at the World Trade Center site was chilling confirmation to many 9/11 rescuers that more than four years later, the disaster is still claiming lives.

“It should open up people’s eyes,” said former firefighter Kevin Riley, who had to retire with lung problems after rushing to the scene as the twin towers collapsed.

A class-action lawsuit claims there have been dozens of deaths related to the cloud of debris that hung over the ruins. Hundreds of police officers, firefighters and others who labored at ground zero have respiratory illnesses and other chronic disorders they blame on asbestos and other substances. And there are others who are healthy now but fear they will develop cancer or other illnesses down the line.

Federal and city health experts say it could take 20 years to find definite links between the toxic cloud and some diseases or deaths, because most cancers take that long or even longer to develop and decades of statistics are needed to prove a relationship.

Last week, though, an autopsy report was released on 34-year-old police Detective James Zadroga, was cited by his family and union as the first medical proof that people are still dying from the attacks.

Zadroga died in January of what was listed as pulmonary disease and respiratory failure. The autopsy found material “consistent with dust” in Zadroga’s lungs, and Gerard Breton, a pathologist at the Ocean County, N.J., medical examiner’s office concluded: “It is felt with a reasonable degree of medical certainty that the cause of death in this case was directly related to the 9/11 incident.”

The autopsy did more than confirm families’ suspicions. It renewed fear.

“I’m sure not just in my household but in other people’s households, the story upsets you, because my wife and my kids read that and obviously in the back of their heads, they think I’m next, so it’s good and bad,” said Riley, 48.

City and federal officials tracking 9/11 health problems insist it is still far too early to know if Zadroga’s death is a “sentinel case” – an early warning of what could be a rising death toll.

Riley and many other Sept. 11 rescuers are receiving disability pay or workers’ compensation for their illnesses. Some rescuers also want to make sure that when they die, they get the full death benefits available to police officers killed in the line of duty – something that would require a change in state law.

But many of the rescuers say the main issue is not the money. Instead, they say, they want clearer answers as to what is making them sick, and better treatment for whatever it is.

“It seems like they’re trying to do the right thing, and it’s good to help people in the future, but they don’t have any answers for us now,” said 49-year-old Joe Sykes, a fire marshal who worked at the morgue at ground zero until the end of October 2001, when his coughing forced him to take medical leave.

“It’s frustrating for me, and frustrating for my family. When they get those answers, are we still going to be alive?”

To provide answers, Mount Sinai School of Medicine is conducting medical exams and screening to track symptoms among rescue workers and construction workers.

Also, city employees and researchers are operating the World Trade Center Health Registry, which uses questionnaires and phone calls to collect information from 71,437 people who worked at ground zero or were in the area. The city registry hopes to monitor their health over decades.

Critics say the research is useless if it cannot be used to help those suffering now.

“If we’re looking 10 or 20 years down the road, then we’re talking about a body count. I’m not looking to do a body count, I’m talking about finding out what problems exist and treating them,” Pat Lynch, president of the city’s police union. “We’re not there to fill someone’s filing cabinet.”