Gary Ginsberg (Toxicologist) gives expert video advice on: What is 'cross-contamination'?; How do people become agents in cross-contamination?; How can kitchen tools be agents of cross-contamination? and more...
What is 'cross-contamination'?
Cross-contamination is a general term that refers to the transfer of pathogens between one medium and another. It can occur because of the common use of things like cutting boards or work surfaces, where the pathogen may come from one type of food and then not be properly disinfected or cleaned away. The pathogen may reside on the surface and then contaminate the next kind of food that comes onto that surface or cutting board. So for example, if you have raw chicken that is being prepared and it has salmonella in it, and then the surface or cutting board is then just wiped clean but not really scrubbed and disinfected, then you cut up a salad on the same surface, you could take the salmonella from the chicken and introduce it into the salad and thereby expose people to it, because while the chicken gets cooked, killing off the salmonella, but the salad doesn't get cooked.
How do people become agents in cross-contamination?
The classic example of cross-contamination is the restaurant worker who goes to the bathroom and doesn't properly wash their hands. And that's why you'll see in the wash rooms, "Employees must thoroughly wash their hands," because we certainly don't want to have the spread of bathroom types of bacteria into our food supply, but if you, as someone preparing food for your family or in a restaurant, people can be agents of transfer of very dangerous bacteria into our food supply leading to typhoid, leading to enteric illnesses from e.coli. So this type of human cross-contamination of food can lead to an array of symptoms, from something as minor as just an upset stomach that you wouldn't necessarily associate with that meal, to something, all the way to serious nausea, vomiting, and even death.
How can kitchen tools be agents of cross-contamination?
In cutting boards, and cooking surfaces, kitchen surfaces, there can be lots of cracks and crevices where it is hard to clean and the bacteria can reside in those areas and the food can still come in contact with. And if you are not cooking that food, it may then lead to bacterial growth in that material that you are serving to people. And so it is really important to try and disinfect surfaces, especially after preparing one kind of food. Especially if it is of animal origin, before preparing the next kind of food that maybe will not be cooked. Knives and utensils can also be places for the accumulation of bacteria and things that need to really be well disinfected, so that you do not transfer bacteria from one type of food to another type of food.
What is 'food poisoning'?
Food poisoning is being exposed to contaminated food, where you take in bacteria that can grow inside of your body and lead to a toxic response, because there are toxins that come from the bacteria that could make you sick, vomiting, elevated body temperature, fever, and can lead to dehydration and even death. The classic with food poisoning is the picnic with the egg salad sitting out for a couple of hours, growing salmonella, and then you get this outbreak of food poisoning coming from people who were at that picnic.
How can produce be contaminated?
Crops that are grown in fields, for example we've had these stories recently about spinach and lettuce. They were being contaminated by e.coli because the water used to irrigate fields is not necessarily purified water, but is water coming from, say, some kind of a pond that has bacterial growth in it. And that's being spread on to the food supply that then gets bagged and never gets sanitized or heat treated, but comes directly to our homes. Pasteurization of milk, we learned, was important to help safeguard the dairy supply but we're certainly not pasteurizing things like crops grown in fields.