The CDC has reported that 46% of all foodborne illnesses are due to fresh produce. One out of every six Americans that will get a foodborne illness this year. “From a historical perspective, fresh produce was linked to less than 1% of all foodborne illnesses in the 1970s, and less than 12% in the 1990s. Why is foodborne illness from produce on the rise?”
Part of the increase is due to better detection, but it is also due to increased use of fast food and a more complex food production/delivery system. Food that we buy in local stores has passed through many hands from farm to table and each step is a possible source of contamination. Another problem is that more people are growing their own food and they incorrectly believe that home grown food is safe.
In this post I will have a look at a number of myths about foodborne illnesses and how you can prevent them.
Myth #1 – Unsafe Food Smells Bad
The microorganisms that cause food to spoil are not the same ones that make you sick. You can’t see or smell the harmful microorganisms (pathogens) and so you can’t tell if food will make you sick by looking at it or smelling it. However, spoiled food does provide a good environment for pathogens to grow, so it is a good idea not to eat it.
Myth #2 – Foodborne Illness Happens Quickly
It is a common belief that the last meal we ate is the cause of any illness but that may not be true. Most food poisoning occurs within one to three days after eating the infected food but it can happen within 20 minutes or even after 6 weeks. It is almost impossible to know which food caused the problem without lab testing.
Myth #3 – Food Poisoning Isn’t a Big Deal
Food poisoning is seen mostly as a short term inconvenience but it can lead to long term health issues and even death. Around 3,000 Americans die from foodborne illness each year.
Myth #4 – You Can’t Catch a Foodborne Illness From Another Person
People do spread some of these pathogens. For example you can catch Hepatitis A from another person through fecal-oral transmission. That is exactly what it sounds like – someone did not wash their hands properly after having a crap. It is more common than you think.
Myth #5 – Washing Produce With Soap Makes it Safe
Using soap or detergent to wash produce is not safe because the chemicals stick to food and are not safe for consumption. Not only that, but they don’t remove pathogens any better than clean running water (ref Microbe Science for Gardeners).
Myth #6 – Washing Produce Removes Pathogens
Many human pathogens attach to food instantly and then form a biofilm that allows them to stick very tightly. The biofilm can be formed in as little as 30 seconds and once formed, the bacteria can be difficult to remove. Some can even withstand chlorinated water baths.
Some pathogens can also invade the internal parts of plant tissues though cuts and bruises. Motile bacteria, such as Escher
ichia coli and Salmonella are especially good at this, and once a pathogen is inside the produce, no amount of washing will remove it.
It is important to keep the wash water at the same temperature as the produce or washing might even hide pathogens in the food. “When sun warmed tomatoes are washed in cold water, the sudden drop in temperature causes the gasses inside the tomato to contract, creating a hydrostatic pressure that sucks in microorganisms“. Such washing has been documented as the cause of Salmonella outbreaks in both mangoes and tomatoes. The rinse water should be within 5°C (10°F) degrees of the produce.
Myth #7 – Peeling Produce Removes Pathogens
Peeling is not much better than washing. Microbes on the outside of the produce easily travel to the newly exposed surfaces through contact with hands and knives. The process of peeling also damages the surface of the remaining tissue, making it easy for pathogens to gain entry into the flesh of produce where they have access to released nutrients, making a perfect environment for pathogens to grow. Don’t peel produce until you are ready to cook it or eat it raw.
Myth #8 – Organic Produce Has More Pathogens
The perception is that organic farmers are more likely to use manure which is seen as a source of pathogens. The reality is that both organic and conventional agriculture use manure but organic use is more regulated, which should reduce pathogens. There are only a few studies that have compared pathogens in the two forms of farming and they have found no differences in the level of pathogens on the produced food. “Only one study noted a greater percentage of E. coli on vegetable samples from organic farms and they concluded the difference was due to the type of produce grown and not the type of agriculture. Further, few studies have distinguished between certified organic and non-certified organic farms. In the one study that did distinguish by farm type, not a single produce sample from certified organic farms contained E. coli, whereas non-certified organic and conventional farms did (as high as 25% of leafy greens from conventional farms, and 30.8% of lettuce from non-certified organic farms).”
Manure use is safe provided it is hot composted (at least 55°C (131°F)) or it is buried in soil well in advance of planting. Reported cases of illness resulting from the use of raw manure are very rare.
Myth #9 – Pesticides Kill Pathogens
Some people believe that conventionally grown food is safer because it has been treated with pesticides that kill the pathogens along with the pest. First of all, both organic and conventional food can be sprayed with pesticides. Secondly, most pesticides don’t kill bacteria.
Spraying with pesticides might even increase the level of pathogens because the water used to mix up the pesticide is usually non-potable water that contains microbes. Some of the pesticides are a food source for microbes, causing microbes to multiply in holding tanks. This problem has been identified as a source of foodborne illness and is being targeted with new regulations. Home gardeners should use municipal water when mixing pesticides, including DIY remedies, and the mixed solutions should not be stored for future use.
Myth #10 – Vegetarians Don’t Have to Worry About Food Poisoning
It is a common belief that food poisoning is mostly the result of eating contaminated meat, but fruits and vegetables are just as likely to make you sick. Leafy greens have been a regular source of illness and need to be washed very well.
Myth #11 – Freezing Food Kills Harmful Bacteria
Bacteria can survive freezing. The lower temperature does slow their growth significantly but freezing does not make your food safe. As food thaws, bacteria come out of dormancy and start to multiply. That is one reason defrosting food on a warm kitchen counter is not a good idea. It is better to do it in the fridge, or quickly in cold water. Once food is thawed, keep it in the fridge until you are ready to cook it.
Viruses, such as Hepatitis A, can survive freezing, freeze-drying, and heat of less than 85°C (185°F). A recent outbreak of Hepatitis from frozen berries is a good example of this.
Myth #12 – Microwaving Food Kills the Bacteria
Microwaves do not kill bacteria. They energize water molecules resulting in heat. Bacteria are killed by high temperatures. Microwave food tends to heat unevenly even with a turntable and so sections of food that don’t get hot enough will still contain live bacteria.
Myth #13 – Food Can be Left at Room Temperature
“Bacteria grow rapidly in the “temperature danger zone” between 4°C (40°F) and 60°C (140°F), and bacteria growth is highest between 21-52°C (70-125°F). Food left at room temperature for more than two hours should be discarded. When the temperature outside is 32°C (90°F) or hotter, food should be discarded after just one hour. This is important to remember if you are preparing food for a tailgate party or picnic.”
Myth #14 – The Five Second Rule
What about food that is dropped on the floor and picked up within 5 seconds, is it safe to eat? No – that’s a myth. The moisture and stickiness of the food determines how many microbes it picks up, but they attach very quickly. Either discard it, or wash it and use it right away.
Myth #15 – Moldy Food is OK to Eat
Maybe. Mold itself is usually not harmful if eaten, but growing mold produces mycotoxins which can make you sick. Remember that mold produces root-like structures that go deep into food – it is not just the fuzzy stuff you see on the outside. If you see mold, it is very likely that bacteria are also growing in the same spot.
On the other hand, some mold is good for you. Penicillin is made from mold and the fungi Penicillium camemberti is responsible for the production of camembert and brie.
Myth #16 – I Don’t Have Pathogens in My Garden
Even if you don’t use manure and don’t have pets, your garden does have pathogens. Every garden has birds, insects and animals using the garden as a toilet and they all add pathogens. Even that organic soil you have contains human pathogens like Listeria monocytogenes and Clostridium botulinum (producing botulin toxin). Water from a rain barrel, compost tea and weed tea can all be contaminated.
You should assume everything in the garden is a potential source of human pathogens. It’s one reason for washing your hands after being in the garden.
Myth #17 – Hot Compost is Pathogen Free
From my book, Compost Science for Gardeners, “Pathogens are killed by heat and time. At 46°C (115°F) pathogens are killed off in a week, while at 62°C (144°F) they are killed off in an hour.” The problem with home compost piles is that they rarely get hot enough to kill off the pathogens and even if they are killed off, more will arrive in the compost during the curing process. Remember that pathogens are found everywhere in the garden. That does not mean you should stop using compost because the benefits far outweigh the risks.
Myth #18 – Water From a Rain Barrel is Pathogen Free
Collected rain water can contain pathogens but it is not a significant source if the water is used properly. For more on this and other myths about water collected in rain barrels see, Myths About Rainwater Harvesting Systems for Gardens.
Foodborne illness is important and can be serious, but it should not be a major source of concern. Follow good hygiene practices. Wash your hands after gardening. Wash any produce you bring into the house, both from the garden and the store. When possible keep the food cold to slow down bacterial growth.
What about eating that fresh strawberry or tomato right in the garden? It is not recommended, but almost all gardeners do it and we live to tell about it. You are now a risk taker!