Chicken

The dirt: Based on the results of a study published inEnvironmental Health Perspectives, the fried chicken you took on this summer's picnics or the grilled chicken from your last barbecue could come back to haunt you this winter. After testing factory-farmed chicken purchased at major supermarkets, researchers detected a drug-resistant strain of E. coli that's responsible for urinary tract infections in women. Once you eat the chicken, the E. coli can live in your intestines and rear its ugly head in the form of an infection as much as six months after you've eaten the contaminated chicken.

Fix it: Eat only organic chicken. Tests on poultry farms have shown that factory-farmed birds harbor higher levels of drug-resistant bacteria like E. coli than organically raised birds do.