Because of recent events and the fact that there is so much misinformation being provided to the public from all sources, ASA suggested to Prof. Meselson that we reprint this article with an update from him to precede the reprint. The original ASA article received outstanding comments from scientists all over the world.

Note Regarding Source Strength
by Professor Matthew Meselson

The "Note Regarding Source Strength" reproduced below is the same as that published in the ASA Newsletter of June 8, 1995, except for the correction of a typographical error (the omission of "pi") in the equation for dose in Table 1.

          Note that source strength is defined as "the number of viable spores released at the source that travel in the atmosphere as particles small enough to initiate inhalation anthrax". Using this definition, the source strength estimates in Table IV are given in milligrams, taking the number of spores per milligram, as stated, as 10⁹. The question of whether the aerosol released at Sverdlovsk consisted only of viable spores or also contained inviable spores and other material is obviously not addressed in the present estimates. These estimates should be regarded only as what they are: estimates of source strength, as defined in the note, that follow from the stated assumptions regarding atmospheric dispersion and regarding dose-response relations for the infectious aerosol and the human population exposed to it.
          Although the present estimates follow from the assumptions made, the most relevant dose-response data available are for non-human primates, not for any human population, and none of it is for the low attack rates observed in the Sverdlovsk outbreak. Neither do we know if the virulence of anthrax spores in the aerosol released at Sverdlovsk was like that in aerosols employed in published experiments with monkeys. And even the well done experiments at Fort Detrick and Porton with monkeys gave ID₅₀ values covering a more than twenty-fold range -- from 2,000 to 45,000 respirable spores. These uncertainties are only imperfectly addressed by considering a number of different dose-response relations, as is done in Table IV.

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An ASA Book Review by: Professor John Ellis van Courtland Moon

Germs: Biological Weapons and America's Secret War
by Judith Miller, Stephen Englelberg and William Broad
New York: Simon and Schuster, 2001.
ISBM 0-684-87158-0.
Bibliography. Index. Pp. 381. $27.00.

          Germs, a fascinating account and analysis of the bioterrorist threat, was written and released before the horrific events of 11 September 2001 and the subsequent anthrax incidents. The accidental timing of its publication has contributed to placing it on the New York Times best seller list. The narrative is largely chronological, stretching from the end of World War II to the present. While the authors convey a sense of simultaneous developments, each chapter is skillfully focused. Chapter 1 describes a little publicized event: the 1984 poisoning with salmonella (of salad bars in Wasco County, Oregon, by the Rajhneeshees, a religious cult, an attack which made 751 people ill. Although the attack was non lethal, the cult fanatic, Ma Anand Puja, had ordered far more dangerous agents. The subsequent investigation did not uncover the causes of the subsequent illnesses until a year later. This incident provided a frightening forecast of the dangers posed by bioterrorism and of the difficulties in detecting and countering it in a timely manner.

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