WHEN I WAS COOKING dinner at a friend's house, I opened the refrigerator to get the prawns we had bought from the wet market. The bag of prawns was on the top shelf and liquid from it was dripping into an uncovered dish of butter. In the fridge were other unwrapped items: some dried-out pizza - two slices, still in the pizza box; a container of yoghurt that had lost its lid and with the yoghurt turning green; and an open jar of pasta sauce so old it had started to grow mould. The kitchen, at first glance, seemed clean - the countertops and cooker were gleaming. But the drawer with utensils was disgusting: everything was sticky with oil and food that had dripped inside. My friend is into fitness - he works out at the gym almost daily - so it seems astonishing that he doesn't seem to care that what he has in his fridge isn't just unhealthy, it is downright unsanitary. When we are children, our parents remind us to wash our hands before coming to the dinner table, but how many of us wash before preparing food? How often do we let leftover food sit at room temperature for several hours before putting it away? When something is turning green and fuzzy or gives off a foul odour, most people will throw it away, although there are the scary ones who scrape aside the mould and eat what is underneath. But food doesn't need to look or smell bad to be harmful. Botulism, found most often in canned foods, cannot be seen, tasted or smelled, but it is one of the deadliest toxins found in food. Other pathogens (organisms that cause illness), such as E.coli, cholera and salmonella, also give no indication of their presence. Sometimes nothing can be done to avoid food poisoning: if shellfish at a restaurant is off or the cooks there have unsanitary kit-chen habits, the customers will probably get ill. But when cooking at home, there are ways to lessen the chances. It is essential to wash your hands with warm water and soap before touching food - most food-borne illnesses are passed through person-to-person contact. If the person preparing the food has bacteria or germs on his or her hands, the people eating the food might become ill as well. Frequently wash hand-towels and cloths used for wiping up spills. My friend and I bought our prawns from the wet market because we were cooking them. If we had wanted to make shrimp tartare that night, we would have bought them from a reputable supermarket that has stringent hygiene standards and keeps fresh seafood in clean water. The same goes with ceviche, carpaccio or any other dish that is eaten raw: it is essential to buy these ingredients from a clean, reputable source with a high turnover of stock. Although most people don't think they can get food poisoning from vegetables, overuse of pesticides and sprays can occur on the mainland. Vegetables and fruits - whether for cooked dishes or salads - should be washed thoroughly. Lettuce, greens and sprouts may look clean, but they can harbour germs, even the products labelled organic. Health-food stores carry a special detergent, Environee Fruit And Vegetable Wash, which rids fresh produce of oil-based herbicides and pesticides. Carefully examine the food you buy. Eschew canned foods that have bulges and dents. Buy only clean eggs without cracks in their shells - salmonella, found most often in poultry and eggs, can get through the smallest break. Store food properly. As soon as you get home from shopping, put frozen foods into the freezer and chilled foods into the fridge. The fridge should be set at four degrees Celsius or colder. Remember that if a fridge is over-stuffed, some of the foods may not get chilled. Leave enough room for air to circulate between items. Cross-contamination occurs when germs are transferred from a contaminated source to clean, ready-to-eat foods. For the prawns we bought, any germs would be killed when they were cooked. But the water from the prawns had dripped into butter which, if it was used for buttering toast, would have carried live germs. Cross-contamination also comes from utensils, whether knives or cutting boards, used for raw or cooked foods. It is essential to wash utensils thoroughly after use, especially after cutting raw meat or seafoods. If possible, have two sets of cutting boards, one for raw food and a second for cooked. Sanitise them periodically in a solution of five millilitres of chlorine bleach in one litre of hot water and wash with dishwashing detergent before using. It is important to remember bacteria thrive in the 'danger zones' between four and 60 degrees Celsius. Hot foods need to be kept hot and cold foods cold. Any leftover foods should be brought to room temperature as quickly as possible then covered with plastic wrap before being refrigerated. Leftover canned ingredients should be transferred to a glass, porcelain or plastic container before being wrapped and placed in the fridge, because the metal in cans may react adversely when exposed to air and acids. Thoroughly reheat leftovers before eating. There is nothing more important than safety. If you are worried about any of the foods you have, remember the motto, 'when in doubt, throw it out'. It is better to waste a little money than to become ill.