This is the first of a three part series
What is in a name? Plenty! The mere hint or even question suggesting that a pesticide might have any medicinal value would strike many as being ludicrous while to many others if not most others, it is beyond belief and therefore there is no need to continue reading. PESTICIDES ARE POISON! They are inherently evil and any attempt to define them in any other way makes one a member of a corporate cabal or a servant of them. For those brave souls still reading, let us begin with a few definitions or concepts – oversimplified but not incorrect.
Poison – disrupts a vital function or functions in a living organism or organisms that could lead to death but not necessarily so. There are many confounding factors including one’s immune system and, most important in toxicology, the dose and which organism is attacked.
Toxin – essentially the same as poison, but with some exceptions largely refers to a substance created by a plant or micro-organism, most often for defensive purposes.
Dose – The well-established principle of toxicology is that: Dose makes the poison. Or as stated by Paracelsus (German speaking doctor, Swiss, Philippus Aureolus Theophrastus Bombastus von Hohenheim, 1493 – 1541) who is credited with the concept: All things are poison, and nothing is without poison; only the dose permits something not to be poisonous (in Greman – Alle Ding’ sind Gift, und nichts ohn’ Gift; allein die Dosis macht, daß ein Ding kein Gift ist). The demand of many for “zero tolerance” violates this basic principle of toxicology and is theology or ideology masquerading as” science protecting the public.” For vital nutrients for humans, there are amounts below which result in deficiencies and above which are toxic often with similar outcomes. Much the same is true for plants.
Medicine – For infectious diseases, medicine would largely be something that kills the living organism that causes the infection. In such instances, a medicine would be a form of poison. Medicine as an anti-biotic is simply the use of a toxin (poison) produced by another living organism – a fungus, bacteria or plant – to kill the living organism or organisms that have invaded the human body and are causing harm or possible death. In the last half of 19th century, with improved microscopes and aniline dyes, scientists could see into the cell and into the blood stream. Koch, Pasteur and others were able to identify the micro-organisms that caused some of the world’s most deadly infections. With the dyes, not only could one identify the micro-organisms, but it was also clear that they responded differently to the dye than did the surrounding blood and tissue. Consequently, if a substance could be found that killed the micro-organism but not the human (or domesticated animal), it would be medicine.
NOTE – Dose makes the poison in medicine in more ways than one. Most everyone knows that not taking enough of a medicine might do more harm than good. For example – patients not completing a treatment for TB led to the emergence of more lethal drug resistant varieties of TB. Dose is also important in that the medicine can kill the infectious agent and also otherwise hurt the patient, known as side-effects. The choice often is between either letting the infectious agent kill you or allowing the medicine to harm you while saving your life.
(On a personal note – I had three of the deadliest infections known to humans. I gave up a leg to survive one of them. For the last of the three, I was being given antibiotics that damaged the kidneys – their more general use had been discontinued decades earlier because of that. The dosage was very carefully monitored as were my kidneys which were “badly” damaged up to the point but not beyond that would allow the kidneys to recover which to my good fortune, they did.) Medicine and poison are therefore relative terms both relative to the organism and as a balance between benefit and harm. Chemotherapy in cancer treatment would be an excellent example of the balance between benefit and harm. Ironically, one says it is a medicine if it is more likely to save you than kill you!
Pesticides – Poisons that could also be considered as plant medicines. (Are you still with me? Have I lost more of you?) In fact, in Indonesia where I worked, pesticides were known as obat – medicine – or obat pembunuh hama meaning medicine that kills disease. Designating a pesticide as medicine may seem preposterous or even insane to the urbanites in developed countries. It makes perfect sense to farmers in many developing countries. Their precious food crops (and other crops) have been regularly getting sick and dying for them and for those who came before them. If they now have something that kills what kills or harms their food crops and allows the plants to return to health, it is medicine in every reasonable sense of that term.
A pesticide as medicine for plants operates with similar constraints as medicine for humans. A pesticide must kill or damage that which is bringing harm to a crop be it a micro-organism, an insect, rodent or another plant competing with the crop for nutrient including light. As with other medicine, a pesticide has to do no harm to the crop or at minimum less harm than that with which it is afflicted. A pesticide has any number of other constraints such as not harming non-target species such as other desired plants, beneficial insects and of course humans. In other words, pesticides must kill a targeted insect or weed without otherwise reducing a desired condition of biological diversity. Like antibiotics for humans, pesticide use must have a strategy of killing targeted micro-organisms, insects or weeds in a manner that minimizes their ability to develop resistance to it.
Are pesticides necessary in agriculture?
With or without pesticides, a farmer has to find ways of protecting her or his crop. The more successful agriculture is, the more it concentrates nutrient in an open field. (We will obviously neglect greenhouses and hydroponics for this note though they are not without problems including invading organisms.) Nutrient for humans is likely to be nutrient for a host of other creatures (but not all) including birds, rodents, other wild animals, insects, micro-organisms etc. and be grown in soil with nutrients that supports competitive plants. One way or another, the crop has to be protected. Farmers have been doing this for thousands of years and it has often been with arsenic and other toxins that afflict the target species but are also toxic to humans and a range of other creatures. Many like Michael Pollan seem to believe that the use of pesticides was an invention of modern agriculture (identified as industrial monoculture) which requires its use while agriculture as traditionally practiced did not.
It is naïve in the extreme to believe that organic farmers do not use pesticides as farmers always have. The USDA has “The National List of Allowed and Prohibited Substances” for organic agriculture which includes both “natural” and synthetic pesticides. Nor is there any evidence that natural pesticides are any safer or better than synthetic ones. A number of the pesticides used by organic farmers are also used by conventional farmers. In other words, natural pesticides have their uses but if they were superior in every way, there would be no need for synthetic pesticides either in organic or conventional modern agriculture.
Most important among the non-target organisms that should not be harmed by a crop protecting pesticide are of course the humans who will apply the pesticides, those who harvest and later handle it and of course the eventual consumers who eat it. There are more short and long term considerations of pesticide use than we can even begin to discuss here which not only complicates the issue but provides for an unending stream of discourse and debate. Rarely do we discuss the problems of not using pesticides beyond that of losing the crop.
Plants in the wild including those that were later domesticated by humans had to protect themselves. They did so by producing substances that are toxic to the organisms that threaten them. Plants were and remain chemical factories that produce a huge array of chemicals. The only choice for those who wish to avoid chemicals in their food had better stop eating. In the fall term, just before Thanksgiving, I circulate a Holiday Menu provided by The American Council on Science and Health listing some of the many chemicals in the foods that grace our table for the Thanksgiving and Christmas Holiday. (For nearly 30 years, I have served on various Boards for ACSH and am currently on the Board of Scientific Advisors.)
Humans through time in domesticating plants have selected through the centuries for matters like taste and yield. Many of these attributes selected for, particularly taste, tend to lessen a plant’s ability to defend itself thus needing more defense from the farmer. Modern plant breeding including biotechnology has allowed for the creation of plants with improved defenses. Even so, plants remain chemical factories. Most plant toxins are secondary metabolites and are largely expressed when the plant is invaded. The greater the invasion, the greater will be the likely expression of toxins.
Nutrients in food: Organic vs. conventional
In recent years, it has been argued that organic produce has more nutrients than conventionally produced produce because they are less well protected. That notion is promoted by organic activist and journalist Michael Pollan; it places him on a slippery slope to a place where he does not want to go. First, most of the alleged increased nutrients are anti-oxidants for which there is no evidence of any benefit. In fact, there are a number of studies that show serious potential harm from too many anti-oxidants including one that shows increased risk of diabetes.
Even more, Pollan in effect concedes a toxin or a poison is not necessarily an absolute and that what is toxic to one organism may be a nutrient to another. Another trick used to allege greater nutritional value for organic food is to pick a nutrient in a food which is a poor source for that nutrient. Thus an otherwise insignificantly small increase in that nutrient can be presented as a large percentage increase. A plane with a safety record of one in a million fatalities is twice as risky as one with a safety record of one in two million but few of us would seriously disrupt our travel schedule just to get the “safer” plane. There are a number of factors that could explain small differences in nutrients other than the ones that those dredging the data are seeking to establish as the cause.
Cherry picking nutrient increases because plants are less well protected ignores the other secondary metabolites also expressed that might not only be toxic to invasive organism but also to humans. As Bruce N. Ames and Lois Swirsky Gold have demonstrated in a number of peer-reviewed articles in major scientific journals, 99.9% of the chemicals that humans ingest are natural but the dosage is sufficiently small as not to be dangerous in most cases. The aptly named confirmation bias allows those convinced of a belief to find a nugget or two of evidence for their convictions in a mountain of data. Ignored are the large scale meta-studies that find no significant difference in nutritional value between organic and conventionally grown food.
The two articles below discuss the nutritional quality of organic and conventional foods:
- “Nutritional quality of organic foods: a systematic review,” The American Journal of Clinical Nutrition, vol. 90 no. 3, September 2009, pp. 680-685
- “Are Organic Foods Safer or Healthier Than Conventional Alternatives?: A Systematic Review, Annals of Internal Medicine”, Vol. 157. No. 5, September 4, 2012
Results: From a total of 52,471 articles, we identified 162 studies (137 crops and 25 livestock products); 55 were of satisfactory quality. In an analysis that included only satisfactory quality studies, conventionally produced crops had a significantly higher content of nitrogen, and organically produced crops had a significantly higher content of phosphorus and higher titratable acidity. No evidence of a difference was detected for the remaining 8 of 11 crop nutrient categories analyzed. Analysis of the more limited database on livestock products found no evidence of a difference in nutrient content between organically and conventionally produced livestock products.
Conclusions: On the basis of a systematic review of studies of satisfactory quality, there is no evidence of a difference in nutrient quality between organically and conventionally produced foodstuffs. The small differences in nutrient content detected are biologically plausible and mostly relate to differences in production methods”.
Safety: Organic vs. conventional foods
The other question is – are they safer. As we will attempt to show below, there is reason to believe that organic agriculture produces a less safe product.
The Bt. protein in transgenic Bt. corn is toxic to insects with a base digestive and receptors for the toxin but not necessarily to humans who eat the corn where the Bt. toxin, a protein is broken down to its constituent amino acids in our acid based digestive system. Certain proteins in tree nuts that can be fatal to some human beings are simply nutritious proteins to other human beings. There is considerable literal truth to the adage that one man’s meat is another man’s poison. There is ongoing international research on proteins that are allergenic to humans.
(See for example – Protein Allergenicity Technical Committee (PATC), ILSI Health and Environmental Sciences, Institute.)
Researchers encountering a novel protein can consult the descriptions of known allergens for similarities. And they can conduct allergenicity tests on it.
Given that increasing yields has allowed more corn to be grown on less land there by leaving more land to return to forests or other vegetation, Bt. corn and other Bt. crops have provided an environmental benefit as has the overall land sparing ability of modern agriculture. Though there is not a scintilla of evidence for any harm from the Bt. corn crop to non-target insects, to the environment or to humans, there is considerable evidence that the crop product itself is safer.
When the corn borer works its way into the corn plant, it will carry a fungus, Fusarium ear rot into the plant. Simply the act of breaching the plant’s outer defenses makes it more susceptible to disease invasion. The Fusarium ear rot express neurotoxins called fumonisins. The Bt. protection reduces considerably any fusarium infestation of the corn crop (Munkvold GP & Hellmich RL (1999) Comparison of fumonisin concentrations in kernels of transgenic Bt maize hybrids and nontransgenic hybrids.”
Fumonisin is spit out by the mold. Fusarium as part of its chemical defense system. For decades, farmers and ranchers have known that animals can fall seriously ill if they eat corn that has been coated with Fusarium, even if the kernels later seem clean. People in parts of the world with high Fusarium growth, most notably the Transkei region of South Africa, have high rates of esophageal cancer. But it wasn’t until 1988, when South African scientists first described fumonisin, that anyone knew exactly why the mold was dangerous.
[Continued in Part II] This blog, the first of three parts, appeared originally in Butterflies and Wheels with the title “A Pesticide as Medicine? Medicine as Poison? Or What is in a Name?” and can be seen in its original form here.
Thomas R. DeGregori, PhD, professor of economics, University of Houston, is an applied development economist, author of books, articles and reviews, lecturer and policy advisor on agricultural development, trade and on science and technology policy with a focus on global perspective.