Curing bacon with a wet brine, without nitrates
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.  


to prevent the production of botulism toxins, it is generally considered safer to err on the side of a little too much nitrate/nitrite than to little.