U.S. postal workers expressed leeriness Thursday over an offer by federal health officials to give the anthrax vaccine to mail handlers to protect them from possible anthrax exposures.

"We're in a state of quandary," said U.S. Postal Service vice president Azeezaly Jaffer. "The employees are hungry for information, and they're trying to understand what it is that the medical community wants them to do."

Federal health officials made the offer Wednesday to postal workers and about 70 Capitol Hill staffers.  Employees have also been authorized to take another 40 days of antibiotics as an additional line of defense against the deadly bacteria. 

Medical experts offered to hand out the antibiotics after they expressed some concern that anthrax spores may linger longer in an individual's lungs than anticipated.

Local health officials said Thursday they are not sure who should take the vaccine and so held off endorsement of the plan.  The U.S. Capitol physician's office proceeded, however, to finalize consent forms created by the Centers for Disease Control and Prevention to give to all potential recipients notifying them of the possible side effects. 

Health officials on a conference call with reporters Wednesday said there are some risks to taking the experimental vaccine.

"The major reaction of the vaccine is a local reaction... redness at the site of the vaccination," said Kathy Zoon, a health official for the Food and Drug Administration. Zoon said the vaccine can also cause allergic reactions such as fever and swelling that can last from several days to a week.

Since the vaccine is approved by the FDA as an investigational new drug, patients must be informed of all the potential side effects and may be asked to participate in a follow-up study to measure the vaccine's effectiveness.

Among those Hill staffers considered at risk are staffers in and near the office of Senate Majority Leader Tom Daschle, D-S.D., whose Hart Senate Office Building suite received an anthrax-tainted letter on Oct. 15 that forced the closing of the building two days later. Daschle said he supports the idea of taking the new vaccine.

"There are people that are leaving for the Christmas holiday season and I think it is important to start vaccinations for those who wish to have them," Daschle said.

Traffic to a question-and-answer session with health officials was light Wednesday, with only about a half dozen staffers showing up.  None picked up the additional antibiotics. 

Prior to the offer, the vaccine was reserved for use only by the military's "special missions" forces.  Several soldiers who were given the vaccine a few years ago as part of the military's vaccination program refused to take it, citing concerns that the drug was not fully tested and that the shelf-life of the doses had expired so they would not be effective. 

Some members of Congress agree that the vaccine is risky.

"I would not say that people shouldn't take the vaccine, but what I would say is that they should know all the ramifications of what they're doing before they take it," said House Government Affairs Committee Chairman Dan Burton, R-Ind., who has followed the military debate.

The 10,000 doses being made available now comes from the Department of Defense stockpile produced in 2001 by the Bioport company in Lansing, Mich., the only company in the nation that produces the vaccine, the Pentagon said Wednesday.

The vaccine being distributed has gone through the full battery of FDA tests to assure its potency and sterility, Pentagon officials said.  Still FDA is keeping a close eye on production after issuing several violations following plant inspections.

At the request of Health and Human Service officials, the Defense Department released 219,000 doses on Oct. 24 for potential use in a domestic anthrax incident. 

Bioport is in the process of developing a large stockpile under the supervision of FDA officials. Production is expected to increase to tens of thousands of doses per month, alleviating supply shortages that caused the Pentagon to radically scale back plans to vaccinate the entire military. 

Fox News' Chris Wright contributed to this report.