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The Food Safety Risk of Organic versus Conventional

The stated principles of organic agriculture are “health, ecology, fairness, and care,” but if you ask people why they buy organic, the strongest predictor is concern for their own health. People appear to spend more for organic foods for selfish reasons, rather than altruistic motives. Although organic foods may not have more nutrients per dollar (see my video Are Organic Foods More Nutritious?), consumption of organic foods may reduce exposure to pesticide residues and antibiotic-resistant bacteria.

Food safety-wise, researchers found no difference in the risk for contamination with food poisoning bacteria in general. Both organic and conventional animal products have been found to be commonly contaminated with Salmonella and Campylobacter, for example. Most chicken samples (organic and inorganic), were found to be contaminated with Campylobacter, and about a third with Salmonella, but the risk of exposure to multidrug-resistant bacteria was lower with the organic meat. They both may carry the same risk of making us sick, but food poisoning from organic meat may be easier for doctors to treat.

What about the pesticides? There is a large body of evidence on the relation between exposure to pesticides and elevated rate of chronic diseases such as different types of cancers, diabetes, neurodegenerative disorders like Parkinson’s, Alzheimer’s, and ALS, as well as birth defects and reproductive disorders—but these studies were largely on people who live or work around pesticides.

Take Salinas Valley California, for example, where they spray a half million pounds of the stuff. Daring to be pregnant in an agricultural community like that may impair childhood brain development, such that pregnant women with the highest levels running through their bodies (as measured in their urine) gave birth to children with an average deficit of about seven IQ points. Twenty-six out of 27 studies showed negative effects of pesticides on brain development in children. These included attention problems, developmental disorders, and short-term memory difficulties.

Even in urban areas, if you compare kids born with higher levels of a common insecticide in their umbilical cord blood, those who were exposed to higher levels are born with brain anomalies. And these were city kids; so, presumably this was from residential pesticide use.

Using insecticides inside your house may also be a contributing risk factor for childhood leukemia. Pregnant farmworkers may be doubling the odds of their child getting leukemia and increase their risk of getting a brain tumor. This has led to authorities advocating that awareness of the potentially negative health outcome for children be increased among populations occupationally exposed to pesticides, though I don’t imagine most farmworkers have much of a choice.

Conventional produce may be bad for the pregnant women who pick them, but what about our own family when we eat them?

Just because we spray pesticides on our food in the fields doesn’t necessarily mean it ends up in our bodies when we eat it, or at least we didn’t know that until a study was published in 2006. Researchers measured the levels of two pesticides running through children’s bodies by measuring specific pesticide breakdown products in their urine. In my video, Are Organic Foods Safer?, you can see the levels of pesticides flowing through the bodies of three to 11-year-olds during a few days on a conventional diet. The kids then went on an organic diet for five days and then back to the conventional diet. As you can see, eating organic provides a dramatic and immediate protective effect against exposures to pesticides commonly used in agricultural production. The study was subsequently extended. It’s clear by looking at the subsequent graph in the video when the kids were eating organic versus conventional. What about adults, though? We didn’t know… until now.

Thirteen men and women consumed a diet of at least 80% organic or conventional food for seven days and then switched. No surprise, during the mostly organic week, pesticide exposure was significantly reduced by a nearly 90% drop.

If it can be concluded that consumption of organic foods provides protection against pesticides, does that also mean protection against disease? We don’t know. The studies just haven’t been done. Nevertheless, in the meantime, the consumption of organic food provides a logical precautionary approach.

For more on organic foods:

For more on the infectious disease implications of organic versus conventional, see Superbugs in Conventional vs. Organic Chicken. Organic produce may be safer too. See Norovirus Food Poisoning from Pesticides. Organic eggs may also have lower Salmonella risk, which is an egg-borne epidemic every year in the US. See my video Who Says Eggs Aren’t Healthy or Safe?

More on Parkinson’s and pesticides in Preventing Parkinson’s Disease With Diet.

Those surprised by the California data might have missed my video California Children Are Contaminated.

In health,

Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

32 responses to “The Food Safety Risk of Organic versus Conventional

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  1. What causes more overall stress? Eating conventional while spending less time and money acquiring that food (assuming the ease of access is less for organic) Or spending that extra time and money on acquiring the organic?
    …It depends on the individual really. Some may experience zero extra stress driving farther and spending more on organic. Others will experience added stress over the opportunity cost of the added time/money to acquire organic.

    Would it be possible to develop a study that would measure this? Its a very individualized matter, so probably not.

    Ultimately, if all variables are the same to source conventional & organic, its logical that organic is best.

      1. Yes WFPBRunner, the EWG does a great job of making practical suggestions on how to start. For me, organic food is prohibitively expensive for the most part… this week even non-organic lettuce is $5 a head, asparagus $5.95 lb.. you get the picture. Having the luxury to grow a garden and forage helps a lot, as does prioritizing according to what I eat the most of. I eat apples every day, so they are most often organic. (and porridge oats, flax, bread etc)

          1. Yes indeed WFPBRunner.. after watching several lectures by Rob Knight on uctv about our microbiome, I started looking at gardening in a whole new way. Just being out there is healing in and if itself. We benefit by the very act of tending plants and digging in the soil. Eating fresh clean vegies is the bonus. Walking the dog, getting some sun and exercise are all part of it too.

        1. The idea is to buy as many plant foods as possible. If you can afford some organic produce it’s better than none. If not, you buy a veggie spray, wash them thoroughly and you’ll still get enough phytonutrients to make your health superior to 95+% of Americans.

          Even Greger supports loading up on non-organic produce if need be.

        2. It freaks me out that the produce we buy, which can also be fed to livestock, costs so many times more than the actual livestock it’s fed to! Not that I ever eat dead animals, but it’s the first excuse given by people who think eating WFPB isn’t in the budget!

          1. Ya think so? I mean, I haven’t examined the topic and done cost analysis, but I’d think the grains and soy they’re feeding livestock is a pretty cheap option. Plus, in general, I think plant foods are cheaper than animal foods.

          2. Livestock are NOT fed the same food humans eat. They get fed reject candy , cheap GMO soy and GMO grains, and the parts of animals that the industry can’t sell

            Believe me, you are eating far, far better with WPFB foods than your local conventionally raised livestock.

  2. Curious: Where do you live that you can’t find organic food within a 15 minute radius? Even our average supermarket here has loads of Organic produce and products.

    1. Casper, Everyone doesn’t live in the city nor suburbs. I have lived in a few areas where it was an hour or so to the nearest BIG grocery chain. On the other hand, I have lived where 3 Walmart Super Centers and many other grocery stores were within 15 minutes.

      1. That’s why I’m asking. Are there still parts of the country where you’d have to drive 1 hour to a supermarket? Please tell us the town and state.

  3. Thanks for this, Dr. Greger!

    I am an certified occupational health nurse in Canada. When I learned of the toxicity at various exposures of parts per million (ppm) of pesticides as part of my training to support the health of workers, I was shocked to see what these chemicals looked like in their molecular pattern.

    Imagine a carbon molecule and the same with bonds all in form and shape. Now, take that shape, crush it, mix it up with some other strange, unrecognizable shapes and voila! You have an image closely to that of the average pesticide molecular structure- a truly disturbing image.

    So I thought about that for about 2 seconds and realized that beautiful structures of coherent bonds of molecules in my body in no way resembled what I was looking at and thus vowed to do all that I could to eliminate as much of those distorted structures from my entering my body as I possibly could.

    Today, I know that I will be exposed to pesticides and a plethora of other chemicals as part of day to day human life but I sleep easily knowing that all the organic healthy whole foods that I eat are paying dividends toward the protection for my well Being.

    Wash everything before you eat it because those poor workers can be working in despicable labour conditions.

  4. I have also decided to add this to any comments that I make on

    I am a proud monthly supporter of Dr. Greger’s work. Please support Dr. Greger’s mission to provide evidence based nutritional information to you so that you and your family can be well- his team deserves your support if you and yours are reaping the benefits of their hard work. ;)

    Bobbi RN OHNC

  5. Would like to attend your lecture listed on your web site on April 27, 2017 at Fresno Surgical hospital. I called them to find time and confirm your lecture. They have no idea who you are and that you intend to speak there. Can you provide more information?

  6. We have bought almost all organic for over 20 years. I have seen a study showing increased nutrients in organic that was not payed for by big agriculture. And it’s easy to taste that organic has much more nutrition in it. I say go by taste over anything. But that means knowing what real organic ripe foods taste like. You have to compare to see. Some things are okay non-organic; fair trade bananas, most mangoes, some avocados. The best source to know what is on your food I have found is

    1. Hi, Sal,

      I did a taste test with organic vs. conventional bananas. Organic tasted more “banana-y.” Maybe it depends on the batch–where they were grown, variety, etc. After that experience, I decided to go for organic bananas. I eat everything organic if possible. I don’t like the idea of poisoning the earth. There are no boundaries for pesticides. They can blow in the wind, get in our water, and ultimately wind up inside us.

  7. OK, so we know that organophosphorus pesticides used in convention farming are bad for human health. But where’s the evidence that the many pesticides typically used in organic farming, sometimes in high concentrations, are safer for human health? In the study discussed in one of the cited videos comparing conventional to organic, the measurements only looked at concentrations of two commonly used OP pesticides. So no surprise that those levels were lower when organic food was consumed. But the levels of organic pesticides were not measured, and as far as I can tell, we don’t yet know if they are less harmful. Organic does not mean pesticide-free.Without a head-to-head comparison, we don’t know, and my impression is that these studies have not been done. If I am wrong about this I’d appreciate someone who knows providing some references. In the study cited comparing conventional to organic, the comparison was only along the dimension of two commonly used OP pesticides. No surprise there. But the levels of commonly used organic pesticides were not measured, and as far as I can tell, we don’t yet know if those are less harmful.

    Organic does not mean pesticide-free or harmless to human health.

    1. Good point David, and yes those studies need to be done. Yet we “trust” that organic certified pesticides are “less” harmful to humans and the environment than conventional pesticides based on the studies that have been done over the years by manufacturers, organic certification groups, etc…that’s why those materials have been approved by organic organizations.

  8. Another VERY important reason to buy food grown without poisons is the degradation of the land that occurs when artificial fertilizers, pesticides and herbicides are used. Support real farmers – not agri-business.

  9. Now a days, Costco is offering lot of organic foods which are even cheaper than non organic in regular shops. Also they have excellent frozen fruits like wild blue berries, straw berries etc for very cheap since nothing is wasted.

    Sprouts also have deals for some vegetables every week. Costco changes time to time to different types of organic vegetables. They always have organic spinach, kale etc. I am very happy that I am able to afford now. Just I have to adapt to buy based on what is available or cheaper.

    We don’t spend money on restaurants much other than Chipolte, which witch sandwich time to time. This can be spent on better products. Mos of the restaurants never care our health since their goal is profit.

      1. Oh it’s hysterical. They’ll be quick to spend $7 on a Happy Meal, but refuse to buy 2 lbs of Organic Kale. They’ll buy a Snapple for $2, but don’t want to spend $2 on some Organic Tofu. They’ll buy a Toxic meat dish for $20+ at a restaurant, but think it’s insane to pay $20 for 4 lbs of Organic Red peppers or 2 Lbs of Organic Shiitake shrooms. LoL

    1. You’re right Sukumar, many of the larger stores are stocking more organic foods, and expanding the produce section. Most stores offer weekly/seasonal sales. I dont eat in restaurants either since switching to wfpb no-oil eating style but will spend time and effort in creating something good to eat at home. To save money, I try to plan ahead what I want to eat in the next week or ten days, I shop for locally grown and seasonal produce preferably. Finally, I made a rule to eat what I buy .. its about having respect for the time, money and effort that goes into my wfpb lifestyle.

  10. There is something that is being entirely overlooked here and everywhere in relation to organic vs conventional. This is possibly because conventional agriculture simply does not have any of what I am about to describe. Many studies, even US government studies, show that a teaspoon of healthy organic humus soil has at least 1 million species and 3 billion individual beneficial soil-based microorganisms. These plant-like microorganisms are either competing against each other exuding protective substances, feeding off each other, or working symbiotically helping each other out.

    As a tiny example, this includes such things as hundreds of species of penicillin, along with every other natural antibiotic ever discovered and many many more, most of which have never been discovered by the pharmaceutical industry. Many soil scientists have proven that these substances become part of extremely complex soil enzymes which are readily taken up into plants. Yet food plants grown in humus rich truly organic soils never cause an allergic reaction to these natural broad spectrum antibiotics, nor is there ever an antibiotic resistant strain. Yes, they are not as potent as the single strain synthetic pharmaceutical antibiotics, but that don’t have any side effects either.

    Few people know that many areas of the conventional livestock industry, and organic livestock industry, get by very well without conventional antibiotics, simply by supplementing with humic substances, which are organic and safe.

    This is only the tip of the iceberg. There are a million other substances like this in organc foods that protect plants, animals, and man, all the way up the food chain. Many of these substances are only recently being discovered. Again, we have not even scratched the surface. Of course pharmaceutical companies are searching for these microbes at breakneck speeds, hoping to find one, patent and synthesize it for profit. Yet in humus rich truly organic food we get the whole broad spectrum of it all, most of which will never be discovered.

    I have hundreds of studies that prove this. These studies also show that the chemicals, fertilizers, fungicides, pesticides used in conventional agriculture kill the beneficial soil organisms. Otherwise mainstream agriculture would not so badly need the chemicals. I have seen fields treated conventionally on one half, and the other half treated organically with rich humic substances that encourage beneficial bacteria, and almost no pest damage whatsoever on the organic half.

    Chinese, Russian, European, Australian, and hundreds of other studies from all over the word show the same thing. I have human clinical medical studies proving what I’m saying here, even dure of incurable disease. So there is no real comparison when organic is done right. There are also a million other life and health promoting substances in organic food. It is not good for the chemical companies or pharmaceutical companies to know this, so the story is not being told. My website tells enough to get the ball rolling.

  11. What’s unfortunate about some of those linked studies is that they only verified levels of blood organophosphates. I’d be really interested into seeing a comparison between blood levels of synthetic pesticide residues vs organic pesticide residues.

  12. I was a tad disconcerted that you make no mention of GMO crops compared to Organic Heirloom crops, THIS is the main reason I buy and grow oganic crops. Plus the taste is way superior, Here in Canada a crop cannot be called Organic if it has been sprayed with chemicals, I know in America the deceit of big Aggri business is being pushed to make out that organic is no different, and as we know this is just another con game.

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