Sterilizing of D.C. mail goes slowly

A week after the U.S. Postal Service began shipping select pieces of mail to Ohio for electron beam sterilization, just two truckloads of treated envelopes have returned to Washington for further inspection, officials said.

The sanitation process, already making slower progress than expected, was interrupted Thursday to ensure that shipments of mail are receiving the proper amount of radiation, according to a spokesman for the sterilization company.

Postal officials initially had hoped the plant would operate around the clock and irradiate three to five truckloads per day. Government-bound mail has been piling up since Oct. 15, when a letter containing anthrax was found in the office of Senate Majority Leader Tom Daschle (D-S.D.).

Since that letter was discovered, anthrax has killed and infected people in Florida, Washington, New York and New Jersey, and several mailrooms on the East Coast and now in the Midwest have been found to be contaminated with anthrax spores.

In response the Postal Service is experimenting with electron beam radiation--also called ionizing radiation--to sanitize the mail. Officials hope to have the technology in place at 200 mail facilities across the country in the next 12 to 18 months, and at least $200 million has been allocated to purchase or lease the equipment.

Titan Industries won a $40 million contract last week to provide the Postal Service with the first eight electron beam irradiation systems and possibly an additional 12. The first machines will go to the Washington area.

By way of Ohio

Until they are installed, the Postal Service is trucking mail destined for congressional offices and the White House to an off-site irradiation plant in Lima, Ohio, run by Titan Industries subsidiary SureBeam. The facility normally sterilizes medical equipment.

The suspect mail--one-tenth of 1 percent of all mail, according to U.S. Postmaster General John Potter--is double-bagged in biohazard-treated material, then boxed. Routine mail such as bills, magazines and catalogs is thought less likely to carry contamination and is not being diverted.

The boxes are shipped from Washington to Lima--a 10-hour trip each way--by Federal Express Custom Critical in Akron because of that company's experience in transporting hazardous material, spokesman Jim Snider said.

The first trucks arrived in Lima on Oct. 25 and 26 and were sent back to Washington on Monday, according to SureBeam spokesman Wil Williams. Postal officials would not say when the mail would be delivered but said it will be inspected again in Washington.

Seven trucks and teams of drivers from FedEx have been tied up with the temporarily delayed project, Snider said.

"Right now there is no activity," he said Thursday. "We have four [trucks] loaded at a mail facility in Washington, but they have not been released. Until they are, there is nothing going on; no units on the highway and nothing being processed. It has been a bit of a bureaucratic nightmare."

`Standard validation'

Williams said the interruption was necessary to make sure the irradiation was working.

"Two weeks ago we weren't in the business of killing anthrax," Williams said. "[The interruption] is standard validation. It's quality control to make sure [the process] is doing, in fact, what we think it is doing."

Postal officials said they chose electron beam radiation to fight anthrax because the technology can be built directly into the postal sorting process. Also, it can be done relatively quickly and its energy source is electricity, rather than gamma radiation. Gamma rays, which can penetrate more deeply, take hours to destroy spores and use cobalt 60, which is radioactive and has greater safety and disposal risks.

In electron beam irradiation, a linear accelerator sends an invisible beam of electrons through matter, breaking up living DNA and killing it. The process may affect organic matter, film, electronics and food; the American Horticultural Association is looking into its effect on seeds.

SureBeam says its electron beam process can penetrate products in packages or cases to a depth of less than 1 foot, depending on the density of the product. To eliminate bacteria in products several feet in depth, the firm converts the beams to X-rays, Williams said.

The letters, in their bags and boxes, move through the beam on a conveyor system. The faster the conveyor moves, the less dosage they receive. Killing E. coli in food takes a fraction of a second under the beam, but the mail will be irradiated for about five minutes.

Higher dosage

Although electron beam technology has been used successfully in the food and medical industries to sterilize everything from herbs, fruits and beefsteak to baby bottle nipples, irradiating letters is a different matter.

"Spores are more difficult; they need a higher dosage than vegetative pathogens such as salmonella and E. coli," said Peter Slade, director of technical services for the National Center for Food Safety and Technology at the Illinois Institute of Technology. "We haven't seen hard data on how much you need to kill spores."

SureBeam is using a dose in excess of 40 kiloGray (kGy), according to Williams. That's the same dose recommended to decontaminate wool and hair of anthrax, according to a report provided by the World Health Organization.

By comparison, the FDA has approved a dose of 1 kGy for fruit and vegetables, 3 kGy for eggs and 7 kGy for hamburgers. Spices can be irradiated at 30 kGy, the highest level approved for food.

"[The method] may not kill 100 percent of spores, but if it can reduce the number of spores by 50, 60 percent, it's good," said Ashok Chopra, professor of microbiology and immunology at the University of Texas Medical Branch at Galveston. "I don't think we have the answer whether this is the best way, but it's a good start."

The consumer group Public Citizen in Washington has expressed concern about using irradiation to treat mail for anthrax, saying there is no evidence to support claims that the technology is safe and effective.