Copper(II) sulfate

Applications in Pharmaceutical Formulation: E519 
 

Copper(II) sulfate is not typically considered a food additive and is not generally recognized as safe (GRAS) for consumption by the U.S. Food and Drug Administration (FDA). In fact, it can be toxic at high doses, so it shouldn't be consumed intentionally.

Copper(II) sulfate does have some legitimate applications in agriculture, such as a fungicide or pesticide, but it's not used in food processing itself. There may be residual amounts on crops treated with copper sulfate, but these levels are typically very low and strictly regulated to ensure safety for consumers.