The sight of Marines unloading equipment near the office builidings, while police stood guard to keep people from approaching the buildings, brought home the severity of the situation to many onlookers.
Capitol Hill Police spokesman Sgt. Contricia Ford said the Marines, along with state, local and federal agencies, were helping with clearing and isolating the area.
Authorities believe the ricin was delivered via a letter or package to Frist's office. Investigators are trying to determine if this incident is linked to poison found last fall in letters at mail facilities serving the White House and a South Carolina airport. Despite a search by hazmat teams from the FBI and the Capitol Police Department, the package or letter that delivered the ricin has not been found.
Investigators are still trying to determine if the ricin found in Frist's office was potent enough to kill and in a form fine enough that it could be inhaled, one of the three ways the others being ingestion and injection that can cause ricin exposure.
According to the Centers for Disease Control and Prevention (CDC), ricin works by getting inside the cells of a person's body and preventing the cells from making the proteins they need. Without the proteins, cells die. Eventually this is harmful to the whole body, and death may occur. The effects of ricin poisoning depend on whether ricin was inhaled, ingested or injected.
Dr. John Eisold, the Capitol physician, said no one has reported symptoms of illness related to ricin exposure. Initial symptoms of ricin poisoning by inhalation, which would probably be the most likely route of exposure for Frist's staffers, may occur within eight hours of exposure. Following ingestion of ricin, initial symptoms typically occur in less than 6 hours.
Within a few hours of inhaling significant amounts of ricin, the likely symptoms would be respiratory distress (difficulty breathing), fever, cough, nausea and tightness in the chest. Heavy sweating may follow as well as fluid building up in the lungs (pulmonary edema). Finally, low blood pressure and respiratory failure may occur, leading to death. In cases of known exposure to ricin, people having respiratory symptoms that started within 12 hours of inhaling ricin should seek medical care.
If someone swallows a significant amount of ricin, he or she would develop vomiting and diarrhea that may become bloody. Severe dehydration may be the result, followed by low blood pressure. Other signs or symptoms may include hallucinations, seizures, and blood in the urine. Within several days, the person's liver, spleen and kidneys might stop working, and the person could die.
Death from ricin poisoning could take place within 36 to 72 hours of exposure, depending on the route of exposure (inhalation, ingestion or injection) and the dose received. If death has not occurred in 3 to 5 days, the victim usually recovers.
Fortunately, testing conducted by investigators shows the ricin did not circulate through the ventilation system.
"As each minute ticks by, we are less and less concerned about the health effects," said CDC Director Julie Gerberding, though health monitoring of Senate workers continues.