ST. LOUIS (AP) -- One of eight people sickened by a dangerous chemical spilled at an Illinois packaging plant remained hospitalized Monday as crews continued cleaning up the mess blamed for shutdowns of emergency rooms at two Missouri hospitals.

Emergency departments at St. Louis County's SSM DePaul Health Center and St. Anthony's Medical Center reopened Sunday, a day after the being closed under quarantine when some victims of the previous day's chemical release at Ro-Corp. Inc. in East St. Louis, Ill., came seeking treatment.

Both emergency rooms were cleared to open after being thoroughly decontaminated, the hospitals said.

Officials said the chemical appears to be nitroaniline, a highly toxic material used in the synthesis of dyes, antioxidants, pharmaceuticals and gasoline.

The Occupational Safety and Health Administration's Web site says the chemical can cause vomiting, diarrhea, convulsions, respiratory arrest and other symptoms.

East St. Louis officials said the spill at Ro-Corp. -- a fence-enclosed business neighboring East St. Louis' public-works department and across from a clinic where a streetside sign, coincidentally, reads "Welcome to Healthy Street" -- was contained and posed no public threat to the community. There were no evacuations.

Steve Robins, president of the G.S. Robins & Co., the parent company of Ro-Corp Inc., has told the St. Louis Post-Dispatch that while it was not immediately clear what caused the chemical spill, the problem was contained by Sunday.

Robins said the workers took showers either at the site or home before going to hospitals.

Three of the victims were released Monday from SSM DePaul Health Center, a spokeswoman said. Three others were medically cleared Sunday to go home from St. Anthony's, while a seventh victim was released by St. Louis' Barnes-Jewish Hospital, spokeswomen said.

One person remained hospitalized Monday in fair condition at Saint Louis University Hospital.

Messages left Monday with East St. Louis' mayor, Alvin Parks Jr., and at Robins' home were not immediately returned.

Price McCarty, an FBI spokesman in Springfield, Ill., said the chemical release was not criminal in nature.

On Monday, orange cones still blocked access to the street leading to Ro-Corp. as cleanup crews -- several in haz-mat outfits and breathing through respirators -- worked on the property cordoned off by red tape noting "DANGER: HAZARDOUS MATERIAL." Two ambulances were parked nearby on standby.

A company Web site says Ro-Corp is a packaging/repackaging facility for dry materials.

(Copyright 2008 by The Associated Press. All Rights Reserved.)