The paragraph is followed by an incomplete phrase or sentence which summarizes the main idea of the paragraph. Choose the missing words of the phrase or sentence.

Today, a variety of safety tests is conducted on a wide range of chemicals and products, including drugs, vaccines, cosmetics, household cleaners, pesticides, industrial chemicals, foodstuffs, and packing materials. The most thorough testing is reserved for drugs and products that will be used in or on foodstuffs. 

The （） of safety testing.