There is a 'resist crew toxins' ability in the game. You just need to mod a component to use it. Personally, I have added it at a very low level to life support since the whole point to life support is to maintain a healthy environment for your crew. As life support tech advances with everything else, the ability of your life support to resist crew toxins slowly increases. I've also added it at a higher level to the medical bay so you get good resistance by having one.
There is also an unused 'resist armor piercing' ability in the game. I've got to mod 'Neutronium' armor back in now that all the radical revisions of the file formats seems to be over.
