Copper in Organic Foods? – You knew all along Organic is no better – Now just admit it to yourself.

To buy organic or not to buy organic: Both are choices that are well supported by science

Copper in Organic Foods?

Jack Dini (Bio and Archives)  Sunday, November 25, 2012


Most people who buy organic produce wouldn’t like the idea that they are getting quite a bit of copper (technically a heavy metal) as part of the bargain. Why copper? Because fungicides based on copper (copper hydroxide, copper sulfate pentahydrate…) are some of the limited options that an organic farmer has to control plant diseases caused by fungi and bacteria, reports Steve Savage. (1) The reason to bring this up is to point out that: 1-  pesticides are used on organic foods, and 2- some of the pesticides that are used on organic are not necessarily safer than those used by ‘conventional’ growers.

Savage adds, “Many consumers believe that by buying organic they are eliminating exposure to pesticide residues. This erroneous concept is often encouraged by some of those who market organic products or those who advocate for organic. There is a long list (1700 products) of the materials allowed on organic published by OMRI (Organic Materials Review Institute). The pesticides on this list (including copper fungicides) are definitely real pesticides (they kill pests) and so they have to be registered for use by the EPA like any other pesticide. Copper fungicides are applied to crops frequently and at several pounds per acre each time. Many synthetic alternatives are applied at a few ounces per acre and less frequently. The best synthetic products not only generate far less hazard, their exposure is also far smaller, and they actually work better for the control of most diseases.” (1)

However, don’t be alarmed by mention of the word ‘copper.’ Copper is an essential element to all species and we would be sick without it. There are more than 10 copper-dependent enzymes which are required by all cells to produce energy. Also, there is little danger that our diet does not provide enough copper, because it is abundant in certain foods. Those with the most copper are sea-foods—oysters, crab and lobster; among meats it is land, duck, pork, and beef which have the most copper; the liver and kidneys of land and beef are especially rich in copper. The plant-derived foods with most copper are almonds, walnuts, Brazil nuts, sunflower seeds, mushrooms and bran. (2)




So, a miniscule amount of copper on organic produce is a non-issue. Even though the copper fungicides are toxic to mammals at certain doses, the EPA risk analysis finds there is an acceptable margin between how much we can get from eating the produce and how much it would take to actually hurt us.

The EPA defines a range of toxicity categories from I to IV, with IV being the least toxic (essentially non-toxic to mammals, but their terminology is classic regulatory-cautious.) On a weight basis, the largest share of pesticides used in California in 2010 (62%)  fall into the least toxic category. Since it’s not easy for most people to relate to the EPA category descriptions, Steve Savage provides comparisons between pesticides and familiar chemicals in foods and pharmaceuticals: “Vitamin C is something which many people take in large, 250-1000 mg doses on a regular basis. Fifty-five percent (55%) of pesticides used in California in 2010 were less toxic than Vitamin C. Sixty-four (64%) were less toxic than Vitamin A. Seventy-one percent (71%) were less toxic than vanilla ice cream or lattes. Seventy-six percent (76%) of the pesticides were less toxic than ibuprofen in products like Advil. Ninety-seven (97%) of California pesticide use in 2010 was with products that are less toxic than the caffeine in our daily coffee, the aspirin many take regularly, or the capsaicin in hot sauces or curries. This is not the sort of image that most people visualize when they hear the word ‘pesticide.’” (3)

One last item about pesticides is this: we get much more natural pesticides than synthetic pesticides in our diet and this has nothing to do with ‘conventional’ or ‘organic’ growers. Bruce Ames and his colleagues at the University of California, Berkeley, report that about 99.99 percent of all pesticides in the human diet are natural pesticides from plants. All plants produce toxins to protect themselves against fungi, insects and animal predators such as man. Tens of thousands of these natural pesticides have been discovered, and every species of plant contains its own set of different toxins.

When plants are stressed or damaged (such as during a pest attack), they increase their levels of natural pesticides manifold, occasionally to levels that are acutely toxic to humans. Ames estimates that Americans eat about 1,500 mg per person per day of natural pesticides and that a person annually ingests about 5,000 to 10,000 different natural pesticides and their breakdown products. (4)

The bottom line in the pesticide argument for buying organic is not compelling in a modern time-frame. If someone wants to spend the extra money for organic, that is their choice. Someone who does not want to buy organic should feel neither guilt nor fear about that decision.  Both are choices that are well supported by science. (3)


  1. Steve Savage, “An unlikely pair: heavy metal and organic produce,”, September 27, 2010

  2. John Emsley, Nature’s Building Blocks, (Oxford, Oxford University Press, 2001), 120

  3. Steve Savage, “Pesticides: probably less scary than you imagine,” science, September 21, 2012

  4. B. N. Ames and L. S. Gold, “Paracelsus to parascience: the environmental cancer distraction,” Mutation Research, 447, 3, 2000

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