Dave's right.
[Usually, if foods that naturally contain nitrates don't cause headaches/migraines, nitrite-cured bacon shouldn't either. That, however, may neither be here nor there, and isn't necessarily germane. Just throwing it out there.]
Curing is all about salt and its concentration in the item being cured.
Nitrite/nitrate helps to prevent problems from C. botulinum bacteria. Though this can certainly be a concern with some items where nitrite/nitrate is used, like deli meats and, especially, sausages, both cooked and air-dryed, it is mostly used in bacon (and other items which will be cooked prior to consumption, to give the characteristic red color and characteristic 'cured' flavor. (Smoke, though, adds its own rather characteristic flavor.)
Celery juice is easiest and most effective to use in a brine injection. Amounts used vary, depending on a few factors. To use along with a dry cure make paste out of the cure, using just enough celery juice to make your cure mix pasty.
If you have a processor, process several stalks of celery, cut into small pieces first, till the result is a mush (to facilitate this, add a little salt to the bowl). Gather up the mush then place is a fine sieve over a bowl and drain out the juice, mashing the pulp with the back of a spoon to extract as much as possible. Add some juice, a little at a time, to your cure mix, and mash with a fork, till a paste is achieved.