Nufarmer November / December 2017 NUF NOV.DEC 17

Nufarmer Africa ACSH Explains: What does ‘Organic’ Really Mean? T he word “organic” has two different meanings. “Or- ganic” may be one of the most confusing words in language today. Although most people will probably have a vague idea of the meaning of the term they probably won’t know the definition. Part of the confu- sion arises from the fact that there are two, very differ- ent, definitions for the same word, one from chemis- try and one from agriculture. The chemistry definition is unambiguous and clear-cut, at least most of the time. Let’s start here. THE CHEMICAL DEFINITION OF ORGANIC In chemistry, the definition is based solely on chemical structure. With very few exceptions a chemical is clas- sified as organic if it contains at least one carbon atom, regardless of its source. This is why organic chemistry is called “the chemistry of carbon.” But there are exceptions. Carbon dioxide certainly contains an atom of carbon but is classified as inor- ganic. Common inorganic chemicals include salt, ammonia, baking soda (sodium bicarbonate), and sulphuric acid. But, like carbon dioxide, baking soda also contains a carbon atom yet is still classified as in- organic. What’s going on? For a chemical to be organic there is an additional requirement. A hydrogen atom must be chemically bound to a carbon atom. Figure 1. Organic vs. inorganic. Formic acid (top) is organic because it contains a carbon-hydrogen bond (red arrow) but sodium bicarbonate, although similar in structure is inorganic because it lacks this bond. Acetonitrile and sodium cyanide (bottom) is another example of the same rule. But in organic chemistry, nothing is ever entirely straightforward. Both carbon tetrachloride and urea (Figure 2) are considered to be organic, despite the fact that neither molecule contains a carbon-hydro- gen bond. These exceptions arise from a historical precedent. THE AGRICULTURAL DEFINITION OF ORGANIC The agricultural use of the term is entirely different from the chemical use. It is a definition of which prac- tices are permitted for food so that it can receive the UDSA Certified Label. According to the USDA: “Organic meat, poultry, eggs, and dairy products come from animals that are given no antibiotics or growth hormones. Organic food is produced without using most conventional pesticides; fertilizers made with synthetic ingredients or sewage sludge; bioengi- neering; or ionizing radiation.” The list of pesticides that are permitted in organ- ic farming can be found here. This brings up an inter- esting paradox, as shown in Figure 3. Chemistry can sometimes be profoundly confusing. This is one of those times. Urea, which was discovered in 1773 by a French chemist, was the first “organic” chemical ever isolated. It is considered to be organic even though the mol- ecule does not contain a carbon-hydrogen bond. Further comments by various role players in science, health and agriculture said the following: One of the favourite organic molecules is methyl bromide (CH3Br; bromomethane), a toxic, which un- beknown to many is naturally produced by vegetables Figure 1 demonstrates examples of carbon- containing chemicals, some of which are organic and some that are not. (broccoli, radish, mustard, cabbage, etc) as a natural pesticide. Ironically, this work was done at UC River- side in California, the state that first banned the use of methyl bromide as a pesticide! There is a shipyard where methyl bromide is still approved for extermina- tion and currently used for strawberries under critical use exemption. Methyl bromide is not banned in the US. There are still approved uses. Also, it is understood that pyre- thrins can be used in organic agriculture. Their syn- thetic analogs, pyrethroids cannot. Almost every introductory organic chemistry text- book offers a version of the origin-story for the “organ- ics” of organic chemistry. It comes from a theory called “vitalism” in which living things were thought to be im- bued with a mysterious vital force that gave them life and distinguished them from dead (inorganic) things. The theory of vitalism was discarded (by all but the most ignorant) in 1828 when Freidrich Wohler prepared urea, a recognized organic substance, from ammonium cyanate, a decidedly inorganic substance, without need of a vital force. It should be noted that urea, perhaps the grand- father of all organic compounds, does not have a hydrogen strain bound to car- bon. Does it matter whether a produce is organic with the ex- ception that it con- tains banned sub- stances that may be carcinogenic? There is no evidence that it provides superior nutrition. If you are worried about pesti- cides, just make sure you buy vegetables which show insects had a first bite! Also Nufarmer Africa | November/December 2017 Figure 2. Both carbon tetrachloride and urea are usually considered to be organic. N either chemical has a carbon-hydrogen bond. This is a rare excep- tion. Figure 3: Clash of the terms. Copper sulphate is an inorganic chemical but is approved for use in organ- ic agriculture. Permethrin is an organic chemical, which is used in conventional agriculture but is not permitted in organic farming. thoroughly wash or soak before use. In South Africa we are led by the nose by many retailers of so-called ‘organic’ products which comes at a price – unfortu- nately it is sometimes also a social ‘in’ thing to eat, dress and drive ‘organic’!(Ed.) Report by Josh Bloom (as appeared in American Council for Science and Health newsletter) 17

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