As a naturally-occurring substance, copper can persist indefinitely. Copper sulfate can kill plants by disrupting photosynthesis. Skin should be washed immediately if contaminated, and work clothing should be changed daily if it is reasonably likely that it is contaminated with copper sulfate. Copper sulfate is blue and odorless. Copper sulfate is classified for shipping purposes as a hazardous substance or hazardous waste.
Copper sulfate is highly corrosive to plain steel, iron and galvanized pipes.
It should not be stored in metal containers. Farm Chemicals Handbook '92. Clayton, G. D. and F. E. Clayton, eds. Patty's industrial hygiene and toxicology. John Wiley and Sons.