On the topic of how much nitrite is needed to "cure" meats, I pulled out Rytek's book, which has a good deal of information on the subject. Dude....you may want to look the other way.
Roughly.....the amount of nitrite needed to avoid botulism poisoning is 200 parts per million.......which translates into 6 grams of sodium nitrite per 100 pounds of meat. It takes 4 ounces of Insta-Cure per 100 pounds of meat, and there are 28 grams per ounce. So the amount of nitrite in Insta-Cure is roughly 5%. That's not much. The rest is salt (and possibly a dye to get the pink color).
It only takes 1 teaspoon of IC to cure 5 pounds of sausage and only 5% of that teaspoon is nitrite? In short, we are talking very small amounts. The reason they mix it with a salt carrier is to assist with measuring that small amount of nitrite. Then there is the problem of getting an even mix, which is why they also suggest you dissolve that teaspoon of IC into a cup of ice water.....to help get a complete and thorough mix into the sausage.
In the actual process of doing this, within minutes of adding the cure to a batch of sausage, the meat will turn from bright pink to a grayish brown color. That is normal and part of the process. When you cook it, the sausage or other cured meat turns pink in color. Also a part of the process.
Bacons, hams, etc. that have been smoked (and partially cooked) are already pink in color.
Lastly, for years, there have been health scares about the safety of eating foods with nitrite in them. Bacon for example. As it was explained to me about 35 years ago, somebody did a study and found that if you fed rats a couple pounds of nitrite, they got enlarged kidney tubules or some such ailment. Ergo, nitrite must be bad for you.
But it turns out that a lot of our foods have nitrite in them naturally....fresh spinach for example. Our own saliva does too......a natural means of protecting ourselves from botulism.
Bottom line........in the amounts we use in smoked meats, nitrite should not be a safety issue. Given a choice of that or a dose of botulism (potentially fatal), nitrite gets a big thumbs up!