Spores, Folds, Glove Boxes and Mail Boxes
Ed Lake
(Updated June 22, 2003)

What is "cross contamination"?

Technically, cross-contamination merely means that a germ is passed from the original source to another person or object and then to another and another, in infinitum.  As this happens, a "clean" object becomes contaminated and then contaminates another clean object which contaminates another clean object, etc.

With anthrax cross-contamination, the process involves the passing along of spores.

What is a spore?

A spore is defined in bacteriology as "A thick-walled bacterium in a dormant or resting stage".  I.e., a germ such as anthrax forms a spore when it runs out of food or when its environment changes in such a way that it cannot survive as a normal living germ.  Itís common to think of it as "drying up", but thatís not really the case since water alone would not revive it.  It requires nutrients and the right conditions to be revived.   Give a spore some food and a warm place - like the inside of a human body - and it "wakes up" and starts reproducing once again.   (Thatís why spores are the source of many many science fiction stories!)

In the picture below, an anthrax spore (B) can be seen still within the dead mother germ that produced it as the mother germ died.  The media anthrax was apparently made up of spores in this form - mostly still within the dead mother germs.  Note how cleanly the spore separates from the dead mother germ.

The following image shows a group of Ames strain spores after they have been refined, i.e., after they have been removed from the dead mother germs and other debris.  The Senate anthrax was in this form.

The Ames strain of anthrax is an excellent strain for research because it reproduces very rapidly when in the right environment.

But it's important to understand that spores are also created by Mother Nature.  The following illustration and text shows the way Nature creates anthrax spores:

How does anthrax cross-contamination occur?

In order to understand how cross-contamination happened as a result of mailing anthrax spores through the mail to Senators Daschle and Leahy, you first have to understand the relative size of things.

The anthrax spores in the letters sent to the two Senators reportedly averaged between 1 and 3 microns in diameter.  A typical spore is between 1 and 1.5 microns in diameter.

A micron is a thousandth of a millimeter - or .001 millimeter.  So, the spores were .001 to .003 millimeters in diameter.

How small is that?  In this situation the best comparison is to a sheet of  paper.  A typical sheet of 20 pound bond paper is .004 inches thick, or .1016 millimeters.

A quick calculation shows that if you laid the spores side by side, you could line up 30 to 60  spores between the two flat surfaces of a sheet of paper.  Like so:

Of course, since paper is really a flattened and dried maze of wood and cotton fibers, the spores couldn't be lined up in a row this way.  It would be more like a colony of ants crawling through a small bale of hay - except that that analogy implies that the spores are crawling along by themselves.  They donít.  A more realistic analogy might be to think of placing a bunch of tiny ball-bearings atop a small bale of hay and then to shake the bale until the ball-bearings start to fall out the other side.  Only ball-bearings arenít a perfect analogy, either.  Ball-bearings have significant weight, and gravity would play a significant part in their movement as the bale is shaken.

These particular anthrax spores were not treated with the secret process that virtually removes any electrical charge.  Because the spores had an electrical charge, they wouldnít fall into crevices in the bale lodge there, nor would the spores cling to the surfaces of the individual stalks of hay.

Under a microscope, the anthrax spores would more likely appear to be floating through the "bale of hay"- like dust particles floating in the air in an old attic - propelled by the movement of the bale and by movement of the air in and around the bale.

The individual wood and cotton fibers are almost certainly a lot larger and more organic in texture than in the illustration above, but the principle is the same.

Getting away from attempts at a perfect analogy and to the actual situation, the spores would virtually float through the paper of the envelope as the envelope is squeezed and unsqueezed by mail sorting equipment and by post office personnel touching it and placing it in stacks and in mail bags.

Touching the anthrax-laced envelope would be like touching a wet sponge filled with a deadly chemical.  Thatís how the cases of cutaneous anthrax happened.

Itís important to realize that there could be hundreds of spores inside a sheet of paper for every one that actually gets through to the other side.

That's what killed 94 year old Ottilie Lundgren in Connecticut.  She had a habit of tearing her junk mail in half before throwing it away.  When she tore in half a piece of junk mail that had been in contact with the letters to Senators Daschle and Leahy, the spores inside the paper of the envelope were thrown out and into her face.  "Death by junk mail!" would be a valid headline for a tabloid.

The Pharmaceutical Fold

Understanding how anthrax escaped from the envelopes is also key to understanding whether or not the anthrax "terrorist" intended for the anthrax to escape the envelopes.  There is a lot of debate over this.  Most scientists do not think the terrorist intended to contaminate the postal system, and I certainly donít think so, but  the FBI and law enforcement officials apparently want to believe it was more than "bad judgment" on the part of the terrorist.  They want the contamination of the mails to have been deliberate.  Mistakes made by a criminal just complicate legal cases.

Elsewhere in this site I discuss several factors that indicate the contamination of the postal system was not intentional.  Hereís another:

Examining the letters within the anthrax envelopes indicates that they were folded in what is known as a "pharmaceutical fold".   Here are the folds on the Tom Brokaw letter:

The "pharmaceutical fold" is the way small quantities of medicinal powders were dispensed for centuries (and itís also the way small quantities of cocaine and heroin are sold today).  The fold is done with two horizontal folds followed by two vertical folds, so that the powder inside the paper is neatly packaged.  Like so:

A normal letter is also folded twice horizontally, but then normally only the right side of the paper is folded in order to make it fit into the small size envelope.

It is also important to note that all the letters had an inch or more cut from the bottom.  This was almost certainly done to make it easier to get the letters into the small post office envelopes after it had been folded with the pharmaceutical fold.  This shows some planning and/or familiarity with folding 8-1/2 by 11 inch paper for placement in a small envelope.

It appears that the anthrax terrorist put the anthrax into the center of the letters, folded the letters around it in a "pharmaceutical fold" and then put them into the envelopes.  By doing that, he took a further precaution to keep the anthrax from escaping into the postal system via openings at the corners of the envelopes or where the glue on the flap doesnít make a perfect seal.  The anthrax not only had to escape from the envelope, it also had to escape from the packet inside the envelope.

And it did.  The tiny spores went though the two layers of paper almost as easily as it went through one layer.  And it went into more layers of paper that were stacked next to them in the post offices.  There is only a slight difference between getting through one layer of paper or two - or three or four.   But the fact that the terrorist packaged the anthrax in a pharmaceutical fold within the envelope would almost certainly be enough to convince a jury that the terrorist didnít realize that the anthrax would escape into the postal system.


One of the questions that must be asked when thinking about the anthrax cases is: Assuming that the anthrax was taken from the processing lab in a vial, how did the terrorist get the anthrax from the vial into the envelopes?

It's not a simple matter to pour anthrax onto a piece of paper, fold it, and then place the paper into an envelope, lick the glue on the envelope, etc.  Any attempt to do this in an open area would be virtual suicide - possibly even if you have been vaccinated with an anthrax vaccine.

As a result, it is very likely that a glove box was used.  Glove boxes can be purchased new for as little as $700 and second-hand boxes are available for much less.  If you are in the right scientific field, you might even be able to get a discarded one for free from your employer.  But if you are in such a field, then you might even be able to use a glove box at the place of your employment during off hours.

A glove box is an airtight chamber with gloves attached that allow a person to use the gloves to reach inside the chamber without exposing himself to the dangers within.  They come in many sizes, and today they are sometimes even marketed for opening mail.

For details and better pictures, check these web sites where glove boxes are sold:


The terrorist brings to the glove box five items: (1) the vial of anthrax, (2) the addressed envelopes and letters (wiped clean of any fingerprints), (3) a large sealable Baggie, (4) a wet sponge and, most likely, (5) some chemical for disinfecting.  (For the letters to the Senators he also brought into the box some cellophane tape.)  The steps from that point are fairly obvious.

1.  The items are placed inside the glove box.
2.  The glove box is sealed.
3.  The terrorist then sticks his hands into the gloves and lays out the first letter.
4.  The terrorist proceeds to slowly pour some of the anthrax onto the letter.
5.  He slowly folds the letter (quick movements stir the air) around the anthrax.
6.  He slowly places the folded letter into the envelope.
7.  He uses the wet sponge to wet the glue on the envelope to seal it.
8.  Steps 4 through 7 are repeated for the rest of the letters.
9.  When done, he places the sealed envelopes into the Baggie.
10.  He uses standard procedures to disinfect the outside of the Baggie and everything else still inside the glove box.

When done, he removes the sealed, letter-filled Baggie from the glove box, and he then heads for the Trenton area mail box where he plans to mail the letters.

At the mail box, he opens the Baggie and carefully dumps the letters into the mail box.

He pockets the Baggie (later destroying or discarding it) and he leaves the area.

(revised Oct. 11, 2002)

Using the bar code, the FBI checked all the possible public mailboxes where the letters could have been mailed, and associated mailbags, and around August 14, 2002, they finally found a trace of anthrax in a mail box at Bank & Nassau Streets in Princeton, New Jersey, right across the street from Princeton University.

For each individual letter, the anthrax was placed onto the letter paper and the letter paper was then folded in the "pharmaceutical fold", which has been used for centuries to SAFELY dispense drugs.  The folded letter containing the anthrax was then placed into an envelope.  The envelope was then dropped into the mail box.  All this was done very carefully.  And the letter probably fell atop other peoples' letters already in the box, and more letters would be dropped on top of them as more people mailed letters.

Question: If the anthrax mailer used a Baggie as I described, how did the spores get into the mailbox by Princeton University?  Did the spores already start leaking through the paper of the letter and the envelope?

Answer:  Probably not.  It takes time and handing for the anthrax spores to move through the envelopes.  Most likely, the outsides of the envelopes were contaminated while the anthrax was being put into the letters and into the envelopes.  While folding the letter, millions of anthrax spores could be fanned around in the glove box.  Some would land on the envelopes.  And when the sealed envelopes were placed inside the Baggie, some spores would also get into the Baggie.

When the postal employee collected all the envelopes in the mail box, the anthrax letters were scooped up and placed in a pouch or tray with all the others from that box.   Still no real cause for the anthrax to move through the paper.

Things quickly changed, however, when the envelopes arrived at the postal facility.  There they were stacked and run through various sorting machines.  The machines squeezed, unsqueezed, bent and unbent the envelopes.  They went between rollers that caused them to snake their way through equipment, bending the letters as they change directions, etc.  They were grabbed by vacuum grippers that remove individual envelopes from stacks and place them in front of humans who examine the zip codes and route the letters to the right destination. (The vacuum grippers are particularly important because they can literally suck the anthrax out of the envelopes!)   Then they go through more twists and turns and squeezing and unsqueezing. That was the process that caused the anthrax to work its way through the folded letters and through the envelopes.

That was undoubtedly the process that contaminated the postal facilities.  And the contamination of other mail began there, too.  Since the letters to the Senators were going to ZIP code 20510 and the letter to Ottilie Lundgren was going to ZIP code 06478 the sorting process would quickly separate them.  It's possible that Ottilie's letter was next to one or both of the Senators' letters at the time when vacuum grippers were grabbing them so humans could check the ZIP codes.  Once the ZIP codes were computerized, it wouldn't be long before the mail would be separated.

After the ZIP codes are computerized, the envelopes are stacked together with other envelopes, and squeezed and unsqueezed again as machines and people handled stacks of letters.  Postal clerks pick up stacks of letters and move them to trays.  Mail carriers pick up stacks of letters and put them in their mail pouches and portable trays.  When handling the stacks of letters, it was like putting a wet sponge next to a dry sponge and squeezing them both.

That's where further cross-contamination of other letters occurred.

Fortunately, anthrax spores are not like smallpox or plague germs.  With the plague, one infected person can infect many others, each of whom could infect many more, and so on and so on.  But with anthrax spores you begin with a finite number of spores and the numbers thin out with each contamination.  The Senators' letters contained billions of them.  It's possible that millions might have gotten onto other letters through cross-contamination, but each successive contamination would involve fewer and fewer spores until there were so few spores on a letter that they would be virtually harmless, because a typical human immune system could easily handle them.

And one wonders what the anthrax mailer did with the Baggies after depositing the letters in the mailbox.  Certainly he wouldn't save it.  And he might not even want to touch it after it had been opened.  He would most likely have disposed of it as soon as possible.  I wonder if the FBI has checked trash cans near the Princeton mailbox where those spores were found.


When speculating on the steps that the terrorist may have followed to commit his crime, there's another question that comes to mind:  Why Tuesday?  Why were all known anthrax letters postmarked on a Tuesday?

The immediate thought is that the World Trade Center attack was on a Tuesday, so the terrorist wanted the other attacks to be on that same day.  But does that really make sense?  Yes, the letters were postmarked on Tuesday, but the letters would not be delivered for two or three days, and the actual injury would happen days or weeks later.  So, all the significance of the day being a Tuesday would have meaning only for the terrorist.  It would mean nothing to anyone else - until much later when it came time in the investigation to speculate about it.

It seems more likely that Tuesday was picked for some other reason,  if it was picked at all.  It might just be the result of terrorist completing his preparations to mail the letters.

Assuming that he has a regular job somewhere, whether he used a makeshift lab or worked off-hours in a professional lab, he most likely refined the anthrax on weekends.  Working all weekend, on Sunday evening he had a vial of anthrax ready for use.

Did he merely hold onto the anthrax for a day just to avoid sending it out on a Monday, which would immediately suggest that he was using some lab on off-hours?  Possibly.  But he needed more than the anthrax to do the mailing, he needed the envelopes and the letters.

Could Monday have been letter-writing day?  He had the anthrax, but he still needed the letters.  It seems most likely that the letters were written after he prepared the anthrax.   Unless he was able to do it or have it done during his work day, the letters were written either late on Sunday or sometime on Monday.  Either way, it was almost certainly a step that took him away from the lab.  And copies also had to be made.

After the letters were written and copied, and after the envelopes were addressed, he then needed to use the glove box to put the anthrax into the envelopes.  Monday evening would be the right time to return to the lab (or a different lab) to do that.  He could then take the letters to a mail box immediately.  Since it would be late and after the last mail collection of the day, the letters wouldn't be postmarked until Tuesday.  Since he's hypothetically a working man, mailing the letters during the day on Tuesday would leave him open to being missed at his work place and being seen at the mail box dumping envelopes out of a Baggie.  Mailing the letters late on Monday night means he won't be missed, and it allows him to dump the letters out of the Baggie with less possibility of being seen.

The letters were postmarked on Tuesday but could have been mailed late on Monday, Sept 17 or any time after the last pickup on Oct. 8.  (There is some dispute over whether there were any pickups on the 8th, which was Columbus Day.  A postal union official says there weren't.  Which means the could have been mailed anytime after the last pickup on Saturday, Oct. 6.  But another postal employee says pickups are always made on Columbus Day. )

Working with the bar codes on the letters, authorities have found that the anthrax letters to the two Senators were most likely processed through the machine that writes the bar codes at around 5:27 p.m. on October 9.  People who have checked the mailbox across the street from Princeton say that mail is picked up from there at 11 a.m. and 3 p.m. daily.  Does it take 2-1/2 hours for letters to get from the post office to the bar code machine?  Or does it take 6-1/2 hours?  The FBI may know, but nothing has been published so far.  It all depends on how many other stops the mail truck makes, how much time it takes to get from the last collection point to the mail processing center, how many trays of mail are accumulated that have to be unloaded, and how much time it takes to stack the collected mail and run it mail through the machines.

And, too, mail collected at that Princeton mailbox most likely gets taken to the Princeton Post Office first.  Then it probably goes onto a truck that leaves at a scheduled time for the Hamilton Distribution center where the mail is bar-coded and postmarked.  The scheduled time of departure for that truck would probably determine when it was bar-coded.

If the anthrax mailer had a need to tell anyone of what he had done, he would most likely have made the phone call from a pay phone between the time he mailed the letters and the time he arrived home.

It's all speculation, of course, but it does make a certain amount of sense.  And when the pieces fit neatly together and make sense, "speculation" can become "probability".


(c) 2002-2003 by Ed Lake
All Rights Reserved