Personnel from other fire departments and first-responder agencies are being asked to take physicals, too - all to be paid for by Formosa, according to the company's spokesman.

"The first responders were contacted by the company through their departments and asked to go to a health screening as a precautionary measure," said Rob Thibault, manager of corporate communications for Formosa.

"Residents, if they have a concern, should call the information hot line at 486-6500, and we'll take care of them on a case-by-case basis."

State, federal and company officials have been testing for a variety of chemicals both on site and in the surrounding area for the past several days. Some things they've tested for include vinyl chloride and other particulates used at the plastics-manufacturing plant, as well as cesium 4, a radioactive material.

The nuclear material was in four gauges at the site, according to Patti Thompson, spokeswoman for the Illinois Emergency Management Agency.

"They are known as level gauges, and they measure the level, or flow, of a product in a vessel. These were apparently on top of the dust collector hopper building, and there were four of them. They were not in the building that exploded but on one adjacent to it," she said.

Thompson said the Springfield Fire Department checked the gauges. In addition, she said, Formosa's radiation safety officer has seen the gauges and closed the shutters on them and said that they appeared to be fine.

Thibault said the Illinois Environmental Protection Agency and Occupational Safety and Health Administration also have checked the gauges.

"Early on in the incident, they did a visual inspection to make sure there was no damage to the units the material was in, and we had EPA and OSHA check them and they're intact, undamaged and still in place," he said.

A massive explosion at the plant 20 miles east of Springfield late Friday killed four of the 18 employees working at the time: Joseph Machalek, 50, Larry Graves, 47, and Linda Hancock, 56, all of Decatur; and Glen Lyman, 49, of Cornland.

Three employees remain hospitalized Wednesday at Memorial Medical Center. They are Bradford Bradshaw and Randy Hancock, both in critical condition; and Chris Havener, who was listed in fair condition.

In addition, four firefighters were treated for minor injuries, two other employees were initially hospitalized and later released, and at least two other employees who initially refused treatment ended up being seen and released at area hospitals.

Illiopolis Fire Chief Brad Stewart, a native of the town of about 900, said he was at the scene of the fire and has been sitting in on briefings twice a day since the blast. He said he feels things are safe.

"I have full confidence there's nothing to worry about in the air, the ground or in the water," he said.

Firefighters from his department also have been told to go to the doctor to get complete physicals, including urinalysis, physicals, stress tests, EKGs, blood tests and other exams. Formosa is also paying for that testing, he said.

Ray Cooke, director of the Springfield Department of Public Health, said city firefighters submitted urine samples that will be sent to a lab that Formosa has contracted with for a full toxicology screen.

"We just decided to collect it here instead of in Illiopolis so the firefighters wouldn't have to travel and the city wouldn't have to pay overtime for them to go there. We don't know when we will get the results back," he said.

"Hopefully, it will show our responders didn't have any exposure on the site at the time."

Sarah Antonacci can be reached at 788-1529 or sarah.antonacci@sj-r.com.