The lawsuit claims that Silverstein Properties and the four construction companies hired to oversee the removal of the 1.5 million tons of debris "should have known that safety precautions were needed to protect the rescue workers and cleanup workers… and anyone else exposed to the caustic dust from the airborne contamination, toxins and other substances."

None of the defendants had seen the complaint at press time and had no immediate comment.

Proper respiratory gear would have allowed the workers to block out smoldering fires, dust, diesel exhaust, pulverized cement, glass fibers, asbestos and other chemicals in order to prevent developing throat and lung diseases, according to a study by the Centers for Disease Control and Prevention. It found that only about one in five of the workers wore respirators while they worked at the site.

The four companies that led the cleanup were Turner Construction, AMEC Construction, Tully Construction and Bovis Lend Lease. According to AMEC's Web site, the company stationed safety experts on site during the cleanup and provided respirators, hard hats and safety goggles to workers.

The suit alleges that many workers did not have access to protective gear, and those who did were not taught how to wear it properly.

"There was no uniform policy on whether or not gear was needed at all, and workers received conflicting instructions," the complaint said.

Some of the plaintiffs suffer from afflictions ranging from tumors to acid reflux. Many say they currently show no symptoms from their work at the site, but have joined the suit because they fear they risk developing cancer in the future.

The suit was filed on the last day before a federal three-year statue of limitations expired for lawsuits related to the terrorist attack. It seeks compensation for victims and the establishment of a system to track for the next 20 years all those who were exposed.

The government is currently funding six separate health screening programs to monitor ground zero workers, but none are funded beyond 2009. Doctors and government investigators told a House subcommittee last week that the current programs are not set up to detect all the serious, long-term health woes stemming from the 2001 attack and cleanup.

The CDC study shows that many recovery workers suffered from respiratory problems long after the cleanup concluded, and that some still battle ailments. Problems include asthma, sinusitis, constant coughing and stuffy nose, facial pains, chest tightness, wheezing and shortness of breath.

The class-action suit, with about 800 plaintiffs, alleges that Silverstein Properties and the cleanup supervisors were negligent and violated labor laws because they were aware of the dangers, including asbestos, and made little effort to protect workers. Contributing to the problem was the city's rush to assure nervous New Yorkers that the air and environment in lower Manhattan was safe, lawyers say.

"The tragic reality is that so many of the brave heroes who worked so tirelessly and unselfishly are becoming a second wave of casualties of this horrific attack, and we're only seeing the tip of the iceberg," David Worby, a lawyer representing the plaintiffs, said at a news conference.