I will be writing more about the US DoD assertion that up to 66 laboratories in 19 states, the District of Columbia and three countries (Australia, South Korea and Canada) received live anthrax spores by mistake from an Army lab at Dugway Proving Ground in Utah. The June 4 WSJ (behind a paywall) says the problem has existed for “over a decade”.
The story seems improbable to me, since the mistake should have been caught fairly quickly, not many years later. Scientists who work with potentially deadly organisms generally don’t take claims of their inactivation by others, elsewhere, on faith: they plate them out and incubate them and check whether there is growth, to be sure there are no live spores, before exposing themselves to a deadly agent. To imply that scientists at 66 laboratories all failed to perform this procedure, which is SOP, strains credulity.
In 2014 it was found that CDC had a similar issue: it was reported that anthrax spores had been ‘inactivated’ using a chemical procedure that was sufficient for anthrax in its vegetative form, but not in its spore form. This was said to have exposed about 80 people at CDC to potentially aerosolized spores. The mistake was discovered when plates were left by chance for a week in an incubator, and late growth was discovered.
The story was that after the chemical treatment, spore growth on plates (into vegetative cells) was delayed but not prevented. The incident exposed several levels of incompetence. Any idiot working with anthrax should have understood that anthrax’ niche as a bioweapon stems from its ability to retain growth potential even after being exposed to extremes of pressure, temperature and dryness (dropped from bombs or airplanes), while in spore form. A spore is anthrax in ‘suspended animation.’ But during active growth, in the vegetative stage, anthrax is very easily killed. (Though you must be sure none of it forms spores before it is killed.) As a spore, anthrax is inactivated only with great difficulty. Which is reflected by how it can start to grow, given the right conditions, even after spending one hundred years or more in spore form.
The CDC mishap informed researchers that they should be alert for delayed growth, when anthrax has been exposed to a procedure intended to kill or damage it, so plates testing anthrax growth should be incubated for longer than normal.
Below are excerpts from 2 abstracts pointing out that irradiation of spores may not always kill them. Many factors influence the dose of radiation required to kill all spores in a bundle, including whether spores are wet or dry, the type of diluent, the geometry of how spores are packaged together during irradiation, type of packaging and spore concentration. These factors are only partly understood. Furthermore, bacteria and spores undergo log killing (as opposed to an all-or-nothing process): a low radiation dose allows, for example, 1/1,000 spores to survive, while a higher dose only allows 1/1,000,000 to survive.
But that is why you test your batch to ensure it is fully inactivated before you expose yourself to it. And Dugway would have been required to do so before shipping it out to others. Dugway produced most of the anthrax that was stored in Bruce Ivins’ flask RMR1029. Dugway has been making large production runs of anthrax for many years. It is not a newcomer to this enterprise.
Also note that when spores are shipped, their packaging within packaging is supposed to prevent any leakage of contents, no matter what type of indignities the package may be subjected to, en route. (There are federal rules that were enacted after leakage many decades ago.) And packages must be tracked carefully as well.
For example: here is part of an SOP published by University of Pittsburgh investigators on what it takes to approve a method for inactivation of select agents (those microbes, like anthrax, designated as high threat agents for bioterrorism):
Standard Operating Procedure for Obtaining Approval
and Safety Testing of a Sample Inactivation Method
- 1. For all sample inactivation procedures, the investigator
and his or her staff must notify the Team of the intent to
inactivate biological materials for removal from the RBL
BSL3/registered Select Agent facility.
- 2. The proposed inactivation procedure must be discussed
either at a strategy meeting prior to initiation of a project or
at the investigator’s standing monthly meeting with the
- 3. Each proposed inactivation method must be described
in detail, along with corresponding safety testing procedures
that demonstrate the lack of viable infectious material
after the inactivation procedure.
- 4. An investigator may use an original inactivation procedure,
or he or she may use an existing inactivation procedure
published elsewhere or developed by another investigator
and listed in this SOP.
- 5. Once the Team has been notified of the inactivation
procedure, the investigator may proceed with performing
safety testing on the inactivated materials. Safety testing is
required for both original inactivation procedures and for
existing inactivation procedures developed by other investigators
or published in the literature.
- 6. If an inactivation method is to be used for more than
one pathogen, safety testing data must be provided for each
pathogen or type of pathogen.
- 7. It is recommended to use a high titer or concentrated stock of infectious agent in the safety testing to provide the
most rigorous challenge to the inactivation procedure…
Gamma irradiation can be used to inactivate Bacillus anthracis spores without compromising the sensitivity of diagnostic assays.
Dauphin LA1, Newton BR, Rasmussen MV, Meyer RF, Bowen MD
The use of Bacillus anthracis as a biological weapon in 2001 heightened awareness of the need for validated methods for the inactivation of B. anthracis spores. This study determined the gamma irradiation dose for inactivating virulent B. anthracis spores in suspension and its effects on real-time PCR and antigen detection assays. Strains representing eight genetic groups of B. anthracis were exposed to gamma radiation, and it was found that subjecting spores at a concentration of 10(7) CFU/ml to a dose of 2.5 x 10(6) rads resulted in a 6-log-unit reduction of spore viability…