Is there any risk of illness from eating a potato?

Yes. Potatoes are grown in soil, where they may pick up the pathogens E. coli and salmonella. These pathogens can be spread from potato to potato if they are handled improperly during harvesting and processing. Potatoes also may pick up the pathogen Listeria in the processing plant. Human hands, dripping water, contaminated equipment, and storage areas--even air-- are all vectors for Listeria contamination.
 
Because they are subject to additional handling, pre-sliced potato wedges and similar frozen or refrigerated potato products are especially vulnerable to pathogen contamination. Slicing, for instance, can transfer pathogens from the skin to the underlying flesh.
 
Over time, whole potatoes also are subject to mold growth and the growth of spoilage bacteria (the kind that don’t cause illness but make the product taste, smell and/or look bad) Moldy or spoiled potatoes should be discarded.
 
Source(s):
Examiner.com "Now a Potato Recall"
Lancaster.gov.uk"Survey on the Microbiological Examination of Loose New Potatoes at Retail"
The Weekly Journal of Rural America "Potato Farmers Adapt to New Food-safety Requirements "