Ah nature, its beauty astounds me and I gladly walk through its many wonders. To think, all it took was time, pressure, and a few chemical reactions to make some impressive features. I am even more impressed by how our means of better living was achieved through nature. Achieved through our ancestors curiosity and survival instincts. As a result many of the proven natural aides are used today, albeit in different form. However, today, we have a population of people who think the world is in trouble. That our world is better served by abandoning our advancements and return to the primitive past. While it is true many of our products used today are nature based; that does not mean abandoning our advances will provide a safer or better environment.
Many things that make life easier came from plants. Aspirin, for example originated from the bark of a willow tree in the form of salicylic acid. Thanks to Bayer and other makers of aspirin, most people no longer have to worry about their stomach becoming upset. Retinal is another plant-based product that has been manipulated to suit our purpose. Cosmetic companies figured out retinal are good for smooth skin. A third chemical, and the focus of this article, is oxalic acid. This is a chemical found in many plants and it is made readily in the lab for industrial and commercial use. Oxalic acid is used in many disinfectants, bleaching agents, and insecticides for household, commercial, and industrial use. As for plants, it can be found in Spinach, Swiss chard, and most notably –if you are a New Englander-Rhubarb.
However, what should be considered safe? Should a chemical extracted from boiled leaves be considered or is the lab created chemical safer? In a very recent Facebook post, I had this exact discussion. The implied argument was making an oxalic acid pesticide from rhubarb leaves is safer and better than buying the same product off the shelf.
This fabulous little article: How to Make Rhubarb Leaf Natural Pesticide Was used to imply and promote a “natural” way of killing insects by the person posting it. The arguments are always the same; start off with the fallacy that things from nature are better. Followed up by sins of science’s past. Nature-philes seem to think sins of the past somehow prove the nature is better argument. Science has numerous sins in it’s past; not many disagree that several mistakes were made. Sadly, those that see science’s ability to change/evolve and create new products that do less harm as a weakness. Those who believe we need to go back to nature feel consistency despite proof is the better way to go. Natural remedies and treatments have been around for thousands of years with little to know change, therefor better. Accordingly, it is better to have the stomach lining irritated by drinking salicylic acid tea from a willow tree, rather than take aspirin. Fortunately, science does not follow this logic. Poisons from the past are either no longer being used or are used in a safer manner then before. Thanks to advancements in science and a better working knowledge, we are better off then our grandparents.
Back to oxalic acid, whether it is created in a lab or extracted from plants it has the same chemical structure and properties. Both plant based and lab based oxalic acid are considered strong acids, both can be used as an insecticide, and both takes about twenty-four hours to biodegrade through aerobic and anaerobic processes.
According to the EPA, if any oxalic acid is found outdoors, it is usually due to the surrounding natural environment and not the result of household use. However, for use as a pesticide, the EPA did a further study and found “A structural activity report indicates that the chemical is practically nontoxic to all aquatic organisms with effect concentrations exceeding 1000 ppm across all taxa. Based on the endangered species level of concern, applications would need to be > 100 pounds per acre to result in the potential for risks. Based on the maximum application rate of 2 pounds per acre, no effects are likely” [EPA 2005]
The above information is for general environmental exposure. The risk of acute exposure to animals and people, should rhubarb leaves be eaten is more significant. The toxicology information seems to vary; according to the Lethal Dose (LD50) 375mg/kg is the limit when tested on rats. When translated to people: an adult at about 145 pound (65.7kg) it would take about 24.6 grams of pure oxalic acid to cause death. However, if you look at Material Safety Data Sheets, they report that a lethal amount can be as little as 5 grams. It has been reported that it takes much less to cause someone to fall seriously ill from the chemical and dogs will die with only 1g/kg. It seems, even with proper measures it is difficult to pin down an exact amount that would cause harm or death. Safety can be very complex and difficult when you are talking about rhubarb leaves themselves. A rhubarb leaf can contain anywhere from .3g – 1.3g of oxalic acid per 100 g of leaves. The amount of oxalic acid varies depending on location, soil conditions, size of leaves, and other variables.
For those who do not know what they are doing, this should be an indicator of the severe problems for their pets and children. The troubling part of all of this is the above recipe for the natural pesticide does not call for exact measurements. It calls for 20 leaves and water. How much water? Do you fill the pot? What if I only want one bottle of it, do I still use 20 leaves? Will I end up making something far more potent than you intended? These are important questions that should have answers to them that are not provided in the above simple recipe. An oxalic acid based pesticide that is packaged will be able to provide you with proper instructions specific to use and area. It offers a greater possibility for control and with proper use –safety. When it comes to things like pesticides, those who do not know what they are doing or have a general disregard for chemistry really should not be dabbling with the unknown. Significant amounts of proper research, especially if you have children should be done before attempting a home brew. Care and proper precautions should be taken to ensure safety will ALL chemicals.
One thing that needs to be made clear is regardless of where the pesticide comes from-nature or lab-it needs to be used with caution and sparingly. All chemicals have adverse affects on living organisms when used improperly. The chance of improper use increases with the uninformed. If someone who knows what they are doing, chooses to use a pesticide from boiled leaves, to save money that is fine. Try a recipe that has more specific instructions then 20 leaves and water. By relying on the claim “all we need to do is go back to nature”, you have set up a potential for greater risk and harm. As shown earlier in this article, obtaining reliable information on this ingredient has proven to be difficult. Why settle for uncertainty and risk, when more accurate possibly reliable versions are available. Lets not fool ourselves into thinking that a chemical is somehow safer because it came from nature. A more valid discussion would be on cost vs. benefit, but safety simply because its natural, is not.