"Farm workers have intimate contact with the fruits and vegetables as they harvest, sort and pack these foods, so worker health and hygiene becomes a matter of concern. Pathogenic organisms of human health significance including Salmonella species, E.coli O157:H7, Shigella, Cryptosporidium, Cyclospora, Hepatitis A, and Norovirus associated with infected farm workers, have been implicated in outbreaks involving strawberries, green onions, raspberries, tomatoes, leaf lettuce, basil, parsley and other produce items."
http://www.pewtrusts.org/~/media/legacy/uploadedfiles/phg/content_level_pages/issue_briefs/pspsummaryworkerpdf.pdf
Emphasis added.
There are no toilets in a tomato field.