Quick Context

Basically I need one of my charaters to produce a lot of chlorine trifluoride, but human biochemistry wont allow that, so I was going to get a micro-organism to do the job and produce it as a waste product on the person's skin (kind of like how bacteria turn our sweat into foul smelling waste).


What microorganism living on the human body would be the best candidate for the job?

  • 4
    $\begingroup$ "ClF3 also violently reacts with water" - your microorganism might have a trouble being part of life as we know it. $\endgroup$
    – Alexander
    Jun 26, 2018 at 18:50
  • $\begingroup$ @Alexander now you see my problem $\endgroup$
    – Amoeba
    Jun 26, 2018 at 18:51
  • 1
    $\begingroup$ Yes, a problem indeed. Some fluorine- or chlorine-based organism might be able to do it, but then there will be a problem for this organism and human body to coexist together. Does it have to be an organism, by the way? Can you use some nanobots that don't have to evolve naturally? $\endgroup$
    – Alexander
    Jun 26, 2018 at 18:55
  • $\begingroup$ @Alexander I would accept that but an organic one is preferred $\endgroup$
    – Amoeba
    Jun 26, 2018 at 18:56
  • 2
    $\begingroup$ ClF3 is a gas. So your creatures are sweating a highly corrosive, explodes with water, literally heat-burns skin acid on their skin? This indicates that their anatomy is really strange, or that they live in non-water-based environments. It might be hard to produce a bacterium that could do that. Could you please specify a little more? Also, why is this a reality-check question? $\endgroup$ Jun 26, 2018 at 19:00

3 Answers 3


This isn't going to happen, for a number of reasons (all of which boil down to "It's dangerous, and these bacteria will kill their hosts").

. . . For more details, please read "Sand Won't Save You This Time", which means exactly what you think it does. Some excerpts:

. . . during World War II, the Germans were very interested in using it in self-igniting flamethrowers, but found it too nasty to work with.

There’s a report from the early 1950s of a one-ton spill of the stuff. It burned its way through a foot of concrete floor and chewed up another meter of sand and gravel beneath, completing a day that I’m sure no one involved ever forgot.

It can be kept in some of the ordinary structural metals-steel, copper, aluminium, etc.-because of the formation of a thin film of insoluble metal fluoride. . . . If, however, this coat is melted or scrubbed off, and has no chance to reform, the operator is confronted with the problem of coping with a metal-fluorine fire. For dealing with this situation, I have always recommended a good pair of running shoes.

Yes. Your best chance of surviving the aftermath of that particular reaction with chlorine trifluoride is to simply run away as fast as possible.

By the way, chlorine and related compounds kill bacteria pretty easily. Chlorine is a great disinfectant in a lot of cases, such as swimming pools. In other words, it would be a bit peculiar for a bacterium to take in a chemical containing chlorine and then metabolize it.

Look, chlorine trifluoride is horrifying even by the standards of Worldbuilding Stack Exchange. You don't want to anything that produces it to be within 10 meters of you - let alone on your skin!

  • $\begingroup$ Even by the standards of WB.SE? Maybe . . . but I think someone, any minute now, will say "Nuke it! It's the only way!" $\endgroup$ Jun 26, 2018 at 19:28
  • 1
    $\begingroup$ Chlorine TriFluoride is probably the most terrifying substance I have ever read about. It burns everything, until there no more left to be burnt. As far as I can tell, there's literally no way to put it out once it starts burning. And it will burn things that we would already consider burnt. $\endgroup$
    – Andon
    Jun 26, 2018 at 20:29
  • $\begingroup$ "chlorine trifluoride is horrifying even by the standards of Worldbuilding Stack Exchange" Well we've got to keep upping the ante :D serious now I wish I could give another +1 just for that $\endgroup$ Jun 26, 2018 at 20:56
  • 1
    $\begingroup$ May spontaneously ignite is giving it the benefit of the doubt. "It is hypergolic [spontaneously ignites] with every known fuel, ... [and] with such things as cloth, wood, and test engineers, ... asbestos, sand, and water". (Emphasis mine; organic chemists don't emphasize such things or they'd be there all day.) $\endgroup$
    – Cadence
    Jun 26, 2018 at 21:48

Living on the human body? No, not plausible.

Parasites that kill their host quickly are never very successful. You want a parasite of of some form living on a human host that produces lots of chlorine trifluoride.

Some problems

The 4-hr Lethal Concentration measured on rats is 95 ppm

Explosive when exposed to organics.

Reacts violently with water.

Everything that applies to the human host, also applies to the biological source of this gas. Biology that we know of relies on water, proteins, fats, etc. that are all just destroyed by this chemical.


It's not possible, since ClF3 reacts with everything, except some metals which are perfectly clean and then have been pre-treated to form a passivating layer. It even reacts with the slag in imperfect welds -- and then with the metal behind the slag because it lacks the passivating layer. Also clothing, concrete, glass, sand, water, fuels, and people.

John D. Clark has a wonderful book Ignition! on the history of the development of rocket propellants in the 40s through the 60s and he has a long section on the inevitably disastrous attempts to use ClF3. It's very entertaining while also being the memories of a chemist who was a major player in the process. Bottom line: They were all insane and just about nothing of what they did would be allowed today.

  • 3
    $\begingroup$ Pre-florinated metal containers is how it's stored (It's actually used for some things!). Weirdly, the OTHER thing it doesn't react to is regular old candle wax. $\endgroup$
    – Andon
    Jun 26, 2018 at 20:33
  • $\begingroup$ "They were all insane and just about nothing of what they did would be allowed today." Science requires sacrifices. $\endgroup$ Jun 26, 2018 at 21:02

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