A 2011 study of reusable shopping bags collected at random from grocery store customers in San Francisco, Los Angeles, and Tucson found that bacteria were present in 99% of the bags, coliform bacteria (which are indicative of unsanitary conditions) were present in 51% of the bags, and E. coli bacteria (which are indicative of fecal contamination) were present in 8% of the bags. The study also found that (1) plastic bags and new reusable bags had no bacteria in them, (2) washing the used bags removed the bacteria, and (3) 97% of consumers never washed their bags.