A study by the USDA’s Food Safety and Inspection Service that observed participants cooking in a test kitchen found that 97 percent of attempts to wash hands failed. That resulted in 48 percent of participants cross-contaminating spice jars by transferring harmless microorganisms that act much like human pathogens. (The USDA reports that Campylobacter and Salmonella, bacteria found in poultry, may survive on food contact surfaces for up to four and 32 hours, respectively.) Another 5 percent of participants in the study transferred bacteria to salads they prepared. It’s worth a reminder: To adequately wash hands, wet them with warm or cool running water, apply soap and for 20 seconds rub hands together vigorously, washing both sides of each hand, between fingers and over fingertips and wrists. Rinse and then dry hands and wrists with a towel, which you should then use to turn off the faucet.