Authorities have issued a stern warning to anyone who discovers debris from the fallen space shuttle Columbia, scattered mainly in eastern Texas: Don't touch.
From corrosive fuels to ammonia-like liquids, insulation and plastics, Columbia was a veritable laboratory of toxic and caustic materials designed to function in the hostile environment of space.
"There's nothing on the shuttle beneficial to humans. The fuel, the propellant, all can be very abrasive," said Gene Perry, an engineer who worked on early space station plans at the Marshall Space Flight Center in Huntsville, Ala.
The excessive heat in the shuttle's re-entry into the Earth's atmosphere likely would destroy any chemicals from the craft, according to the Texas Department of Health (TDH), however authorities have not ruled out the possibility of serious human harm from direct contact with the debris.
Authorities in eastern Texas said eight people have been treated at a hospital after coming into contact with debris from the space shuttle.
An emergency management coordinator in the region, Bill Ted Smith, said the people were all civilians. He said they were treated for burns and for respiratory distress -- after handling shuttle debris or breathing vapors from it.
A check of area hospitals tallied about 84 others who had shown up at hospitals or emergency rooms, but none needed treatment, Doug McBride, press officer for the TDH, said Sunday.
Two toxic liquid fuel components, monomethyl hydrazine and nitrogen tetroxide, could have been present at the end of a shuttle voyage, according to a statement from the Center for Disease Control.
But based primarily on the physical characteristics of both liquids the CDC has concluded that neither component is "likely to have survived the descent of almost 40 miles in a concentrated liquid or solid state."
"The general population in the area of falling debris and with no close contact with the debris is not at risk from either chemical," the CDC said in a statement.
"NASA data indicate that no other toxic or radioactive substances were present in quantities likely to pose a danger to health."
Sheriff Tommy Maddox of Sabine County, Texas, said residents have expressed concern about the water from an area lake. He said he spoke with federal authorities and with experts who assured him that the water supply was safe.
Some shuttle pieces dropped into Toledo Bend reservoir, along the Texas-Louisiana line, causing the closure of a water plant in the town of Many, La., which supplies half of the drinking water to Sabine Parish.
Many Mayor Ken Freeman said there were fears toxic debris fell into the reservoir. "To be safe rather than sorry we closed the water plant until further notice," Freeman said.
Not all the water plants using the lake were closed, but wildlife officials closed Lake Vernon, also for fear of toxic debris.
The TDH issued an advisory to East Texas physicians and hospitals to provide them with information about the treatment of persons who have been in contact with possible debris from Columbia.
After the shuttle explosion, as with any mechanical event involving solids and high energies, airborne particulates could have been produced, the CDC reported.
Only those with particularly close exposure to the debris would be in danger of the health effects of the particulates such as respiratory irritation, cough, and (in high concentrations) difficulty breathing, the CDC said in a report. Persons in the general vicinity of falling debris were not considered at risk.
TDH said it was advising medical personnel to provide standard treatment for respiratory or chemical burn symptoms and to keep a registry of all persons who show up at medical care facilities reporting contact with shuttle debris.
Much of the debris scattered across Nacogdoches, where authorities ordered people to stay 100 yards away from the debris because of contamination fears.
"What we fly in space is operated in many cases with toxic propellant and some of the debris may be contaminated, so we need to be careful," shuttle program manager Ron Dittemore said.
Shuttles have long used a chemical called hydrazine to run their auxiliary power units. Hydrazine, a colorless liquid with an ammonia-like odor, is a toxic chemical and can cause harm to anyone who contacts it.
The Associated Press contributed to this report.