Cross-contamination — the transfer of harmful bacteria from raw food (especially raw poultry, meat, seafood, and eggs) to ready-to-eat food — is the most common cause of foodborne illness in home kitchens. The vectors are hands, cutting boards, knives, towels, and any surface that contacts raw protein then contacts something that won't be cooked. Professional kitchens prevent this through colour-coded cutting boards, separate prep areas, and rigorous handwashing protocols. Home cooks need simpler but equally effective habits.
Never use the same cutting board for raw protein and ready-to-eat food (salad, bread, cooked food) without thorough washing between uses. Better: use separate boards. Wash hands with soap for 20 seconds after handling raw meat, poultry, eggs, or seafood — before touching anything else. Never place cooked food on a plate that held raw protein. Never reuse a marinade that raw meat has been in unless it's boiled for at least 1 minute first. Keep raw proteins on the lowest shelf of the refrigerator to prevent drips onto other food. Thaw in the refrigerator (never on the counter) or in cold running water.
The two-board minimum: one board for raw proteins (ideally plastic, dishwasher-safe), one for everything else. Colour-coding is the professional standard — red for raw meat, green for vegetables, blue for fish, yellow for cooked meat, white for dairy/bread. For home kitchens: at minimum, wash the board with hot soapy water and sanitise with a dilute bleach solution (1 tablespoon per gallon of water) between raw and ready-to-eat tasks. The 'danger zone' is 4-60°C (40-140°F) — bacteria multiply rapidly in this range. Get hot food into the fridge within 2 hours of cooking.
Using the same cutting board and knife for chicken then salad without washing — the single most dangerous home kitchen practice. Tasting a marinade that raw chicken has been sitting in. Washing raw chicken under running water — this SPREADS bacteria across the sink and surrounding surfaces (Health Canada, USDA, and FSA all advise against it). Leaving cooked food at room temperature for more than 2 hours (1 hour above 32°C). Using the same towel to dry hands after handling raw chicken and then drying dishes.