Shopping Carts can be the most contaminated of HPC (heterotrophic) Bacteria on public surfaces per a study by the University of Arizona, “Occurrence of Bacteria and Biochemical Markers on Public Surfaces”, developed by the Department of Soil, Water and Environmental Science.
Shopping Carts can have as much as 2,100,000 Colony forming units of bacteria on its surfaces as compared to the next most contaminated surface, Elevator Buttons, with 15,000 colony forming units of bacteria.