When making bacon, many of the recipes call for a dry brine using curing salt with nitrates. I've read that it is possible to use a wet brine without the curing salt with the nitrates and just use Kosher salt (or some other salt). Is this possible and safe to use just kosher salt and water? From my understanding curing salt with nitrates can be toxic, but also protects against botulism but I'm still looking for a safer alternative.
Salt inhibits bacterial growth mainly by drawing moisture out of the meat. A wet cure (brine) would be substantially less effective at this than a dry cure, unless you add much more salt to your brine and, also, you take the extra step of drying the meat afterwards. Besides, the texture of the final product is likely to be substantially different, possibly not in a good way.
As you alluded, potassium nitrate (a/k/a saltpeter) is used in cures because, strangely, it does indeed stop the growth of Clostridium botulinum, the bacteria that causes botulism. Other salt cures do not have this property, which might explain why some recipes call for adding a little powdered ascorbic acid to the salt. Hopefully, however, you are not planning to leave your bacon in a vacuum-sealed bag at room temperature, so this should not be a major factor in which cure recipe you use. I would be far more concerned about generating carcinogenic nitrosamines from frying nitrate-laden meat.
Nitrate, through the action of lactobacillus in meat, breaks down into nitrite. Nitrite then rapidly breaks down releasing nitric oxide, which combines with myoglobin present in muscle tissue, 'curing' the meat. When this process is complete, and if the correct amount of nitrates/nitrates were used in the cure, almost* all of the nitrate/nitrites will be broken down, and very little residual nitrates or nitrites will remain in the bacon.
Nitrosamine formation in bacon is the result of cooking it with high heat, but this is not limited to bacon - grilled hamburgers or steaks contain equally high levels of nitrosamines. To greatly reduce or eliminate nitrosamine formation in bacon, simply fry it at a low temperature. It will take longer to cook this way, but will cook more evenly and spatter less.
But if you're really worried about nitrosamine consumption, give up grilled meat. And just to be safe, better give up green leafy vegetables too. Spinach, for example, and celery (which contains 800 times more nitrate than cured bacon) produce nitrosamines in the stomach and digestive tract. Ascorbic acid is added to accelerate the curing process and has no effect on botulism prevention.