"Because organic foods use pathogen-laden manure as their primary fertilizer, organic foods may pose a higher risk of foodborne-illness than conventional foods," he said, adding that damage from pests is likely to be greater, as well, and that could translate to more fungal growth, or colonization by molds. Some of these organisms produce toxins. One of them, aflatoxin, is considered highly carcinogenic.
DiMatteo said manure is used -- but that restrictions and procedures are used in handling it. Plus, it's only part of the overall soil plan.
"The organic system for soil fertilization includes crop rotation, cover crops, composted vegetable matter and manure," she told CNN.Com.
That's fine, according to the United Fresh Fruit and Vegetable Association, provided the manure is properly composted.
"Uncomposted or improperly composted manure that enters surface waters many contain pathogens and subsequently contaminate produce," the association warned.
Food safety experts say organic or not, consumers have to observe the same rules if they want to avoid getting sick. Thoroughly wash -- even scrub -- all produce. And, if the skin won't come clean, peel it off.
Organic livestock may have had the run of the farm and eaten pesticide-free grain, but that doesn't mean they won't come to slaughter loaded with bacteria. Just like conventional chickens, organic birds can harbor salmonella, E. coli and campylobacter. These can cause anything from a mild intestinal illness to a life-threatening infection. To avoid that, organic chickens (or any organic meat) should be handled the same as a regular product -- observing cleanliness rules in the kitchen and making sure they are cooked to the proper temperature: 180 degrees for poultry, 160 degrees for beef.