Top Scientists Link Lethal Anthrax to U.S. Weapons Program

by William J. Broad
The New York Times
December 3, 2001

The dry powder used in the anthrax attacks is virtually indistinguishable in critical technical respects from that produced by the U.S. military before it shut down its biowarfare program, according to federal scientists and military contractor documents.

The preliminary analysis of the powder shows that it has the same extraordinarily high concentration of deadly spores as the anthrax produced in the American weapons program. The possibility that the anthrax came from a foreign source remains, but the spore concentration is higher than any stock publicly known to have been produced by other governments.

The similarity to the levels achieved by the U.S. military lends support to the idea that someone with ties to the old program may be behind the attacks that have killed five people. The FBI recently expanded its investigation of anthrax suspects to include government and contractor laboratories as a possible source of the deadly powder itself, or of knowledge of how to make it.

Its high concentration is surprising, weapon experts said, and far better than what military analysts once judged as the likely abilities of terrorists.

Still, experts caution that the emerging evidence is tentative, and that it is too early to rule out other possible suspects, be they domestic lone wolves or hostile foreign states like Iraq.

A yardstick for measuring the quality of anthrax emerged more than two years ago when William C. Patrick III, a longtime federal consultant and one of the nation's top experts on biological weapons, wrote a report assessing the possible risks if terrorists were to send anthrax through the mail. Based on the difficulty of developing advanced anthrax, he predicted that the terrorist germs would be one-20th as concentrated as what the government developed and what recently turned letters into munitions.

"The quality of the spores is very good," said a federal science adviser who shared the Patrick report with The New York Times. "This is very high-quality stuff" - equal, he said, in concentration to that produced by the U.S. military before it abandoned germ weapons.

The high quality, the adviser said, lends credence to the idea that someone with links to military laboratories or their contractors may be behind the attacks. "It's frightening to think that one of our own scientists could have done something like this," he said. "But it's definitely possible."

He said the anthrax sent to the Senate contained as many as 1 trillion spores per gram, a figure confirmed by an administration official.

And with that concentration, the powder has a vast potential to kill. Estimated conservatively, at 10,000 microscopic spores to a lethal dose, a gram in theory could cause about 100 million deaths.

The letter sent to Tom Daschle, D-S.D., the Senate majority leader, is said to have held two grams of anthrax - enough, in other words, to make about 200 million lethal doses, assuming it could be distributed to victims with perfect efficiency.

Analysis of the Daschle powder has been hampered by the small amount recovered after an aide opened the letter, and by technical missteps as the investigation got under way, making some conclusions tentative. That is why investigators are taking great care in opening the anthrax-contaminated letter sent to Sen. Patrick Leahy, D-Vt., chairman of the Judiciary Committee. The aim is to scrutinize the evidence as closely as possible.

Spore concentration is just one factor experts will examine in the Leahy letter, and their findings could significantly alter their picture of the powder. Other factors that signify the quality of anthrax production include whether the powder has been ground to a size that easily lodges in the lungs, and whether it has been treated to make it static free and free-floating. Investigators will look for anti-static additives that may be a possible hallmark of a particular government's weapons program.

Patrick, in his risk assessment, sketched out both what the American military achieved and what a terrorist might do. His 28-page report, dated February 1999, was written for a federal contractor advising the government on how to handle the growing number of anthrax hoaxes and what to expect if real anthrax was sent through the mail.

"When these hoaxes first came up, we assumed none of the bad guys" could achieve high-grade anthrax, said a contractor official, who spoke on the condition of anonymity.

It is unknown publicly exactly how makers of anthrax weapons achieve high spore concentrations, but the black art is said to involve precise drying, sifting, milling and removal of impurities.

In his assessment, Patrick drew on personal knowledge acquired while working in the nation's offensive biological weapons program between 1951 and its dismantling in 1969, at which time he was chief of the division of product development. He won five patents with his colleagues on ways to make biological weapons.

His 1999 report focused on what kinds of contamination terrorist anthrax would cause when a letter was opened and what the requirements for decontamination were.

Patrick postulated that the concentration of anthrax would be 50 billion spores per gram. "This assumes a dried powder of moderate ability to generate into an aerosol when the envelope is opened," he wrote.

He predicted that an envelope would hold 2.5 grams of anthrax - an amount strikingly close to what is thought to have been mailed to Daschle.

In his report, Patrick said the American program had achieved a concentration of 1 trillion spores per gram - what scientists today say is near the theoretical limit of how many of the microscopic spheres can be packed into a tiny space.

Today, no terrorist or scientific maverick is known to have published anything close to describing how to make concentrated anthrax powders. Timothy W. Tobiason, a habitue of gun shows who sells a self-published cookbook on how to make germ weapons, including "mail delivered" anthrax, sketches out only the most rudimentary steps.

Experts judge his recipes as flawed in spots and at best capable of producing only low-quality anthrax. The book deals mostly with the production of wet anthrax, though it does suggest a way to grind clusters of dried anthrax into microscopic pieces, which can settle into the lungs.

It is unclear if any foreign nation has achieved high anthrax concentrations. The United States suspects that more than a dozen countries are clandestinely studying biological weapons, with anthrax among the top agents.

Ken Alibek, a former top official in the Soviet germ weapons program, who is now president of Advanced Biosystems, a consulting company in Manassas, Va., said that it was routinely possible to create dry anthrax that contained 100 billion spores per gram and that, with some effort, 500 billion was possible.

"The infectious dose," Alibek said, "can be quite large."

Still, the 500 billion figure is half the concentration that the American government and whoever sent the letters are said to have achieved.

"I don't think they're manufacturing this in caves," Alibek said of the terror anthrax. "It's coming from another source."

Copyright 2001 The New York Times Company

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