At present, the majority of consumers lack proper understanding with preservatives. It is mainly summarized in the following areas: preservative toxicity, accumulation issues, varieties of the problem.

For example: the nitrate family preservatives: Sodium nitrate, potassium nitrate (Huoxiao) and sodium nitrite (Fast Glass), are commonly used in meat products with their anti-oxidation and corrosion ,and also can prevent fresh meat to be oxidized into Gray-brown myoglobin denaturation gradually in the air, and then ensure the freshness of meat. Nitrate is also highly toxic inhibitors of Clostridium botulinum. Therefore, the nitrate has been essential meat products, such as bacon and sausage.

However, the nitrate, added into the meat, is prone to be restored into the active carcinogen: Nitrite. Under the action of a certain acidity, nitrite can also work with the N-nitroso-nitroso-myoglobin to synthesiz myoglobin. Muscle color of the original also has carcinogenic properties.

On the other hand,amino acids, phospholipids and other organic substances of meat protein, under certain conditions and environment, can produce amines.Amines will react with nitrite produced by the nitrate to N-nitrosamines.

The larger doses of intake nitrate and other types of preservatives such as benzoic acid, sodium benzoate, sorbic acid and so on, can affect the body's normal function, reduce the human immune system. All of those have provided favorable conditions for the variation of human cells.