Both potassium sorbate and sodium benzoate have been deemed safe for consumption and are not harmful when consumed in small doses. However, there are concerns about the dangers of consuming too much over a prolonged period of time as well as being dangerous to certain people.
Sodium benzoate and potassium sorbate are commonly used preservatives that are added to many regularly consumed and used products. While they are not harmful in terms of immediate effects after using or consuming, there is no definite answer pertaining to long-term effects as it depends quite a bit on individual factors, such as how frequently a person uses or consumes products with these additives or whether a person has an allergy to them.
Most of the issues relating to potassium sorbate and sodium benzoate arise with excessive consumption over a long time. There is insufficient information about the long-term effects of consuming too many products containing these preservatives. However, when sodium benzoate is combined with vitamin C, they produce a carcinogen called benzene that is believed to cause DNA damage.