Organic Pesticides vs. Synthetic Pesticides
by Dennis J Gleason

Chances are more than good that if you are getting your produce or grain products from something larger than a regional or local farm, the pesticides used by those farms may be synthetic, rather than organic. It’s a matter of cost vs. eco-friendly; so don’t get your hopes up too high, especially in this economy. Theses are businesses first, and environmentalists second (if at all).

Luckily, there is an ever-increasing public awareness aimed at the benefits of organic… everything. Not co-incidentally, pesticides are high on that very same list. As far as health and safety are concerned, you may not want to hear this, but the best pesticide (organic or synthetic) is NO pesticide. That method, by the way, actually is possible, if not always practical, but is also a topic for another day. The uncomfortable truth is, that more than a few organic or ‘safe’ pesticides are not as safe as you (or the retailers who sell them) might like to believe. Here are some examples:

Pyrethrums- Basically, a powder made from Chrysanthemums. What could be more natural, right? Well, it’s a neurotoxin, so be careful. Dust the plants with it, and the bugs are history. Unfortunately, that’s especially true for honey bees, who’s numbers are diminishing worldwide at a disturbing rate. There are also synthetic forms of Pyrethrums, just to keep you on your toes, if you’re trying to stay dedicated to ‘organic only’ gardening/farming.

Sabadilla- It comes from the a lily with the same name. It too, is a powder that is dusted or sprayed on plants and consequently ingested by a variety of insects. The powder then poisons them via their stomachs as well as by contact, and kills them. It acts as a paralytic, therefore, in certain level doses, it is also dangerous to humans. Over-exposure to humans will slow heart and respiratory activity with cumulative effects which disappear very slowly. Despite the health risk, it is regularly used in homeopathic medicine, (in smaller doses, of course) for among other things, hay fever. It is also destructive to mucous membranes in mammals. As a pesticidal dust, it is usually blended with lime or sulfur mixtures. That means you and your pets are especially susceptible to eye and skin irritation. Did I mention that that it too, is an extremely effective bee exterminator?

Rotenone- sometimes a powder, sometimes an emulsion, Rotenone is made from the roots and stems of some legumes and vines. (Now c’mon… THAT sounds organic and safe, right?) It is used to kill mites in chickens, but is also used to kill snails in fisheries, as well as fish in general, in various application of regional water management. Humans can consume those fish safely because Rotenone is not absorbed by the human gastrointestinal system. However, recent as well as current research is trying to connect regular exposure to rotenone with Parkinson’s Disease. As of yet, that research is inconclusive, but studies are ongoing.

By now you may be wondering if all of the organic pesticides are dangerous. Well, the short answer is the obvious one: They kill things, so yes, they naturally present a risk (albeit naturally). But some present a degree of risk, which is lower than others. Here are some of those:

Insecticidal Soap- Relatively, one of the safest organic insecticides, but not without it’s limitations. It is only effective while it is wet, so it must be sprayed directly on the invaders. Too much can burn and/or shock the plant or vegetable, and application in direct sunlight or high heat will compromise the plant as well as the pesticide itself. But it won’t hurt bees, pets, or you, making it the model of ‘organic = safe’ pesticides.

Neem Oil- Neem Oil is the Swiss Army Knife of organic farming, (among other uses) and is extracted from the evergreen tree of the same name, typically found in India. It is comprised of dozens of chemicals, so it is useful on a wide variety of pests. It is more of a repellant than an insecticide, but it is also effective eradicating a variety of larvae. Unfortunately, it works very slowly, and so regular application must be done with diligence. It’s safe for humans, honey bees and even lady bugs, but pets, should stay away from it at least until it dries.

Bt- Formally known by its full name: Bacillus thuringiensis, (which by comparison, makes Irish wristwatch seem easy to say) is a microbial insecticide. It is a bacterium that specifically targets certain insects and eliminates them by paralyzing the digestive system. It has many strains and can be engineered to target only certain insects. Think of it as a bio-weapons system for gardeners. Long-term studies have shown no ill effects in humans. Certain formulations can be beneficial to virtually all farm produce, making it one of the most popular insecticides.

The next step in this war with insects falls under the aegis of the category known as ‘Plant Incorporated Protectants’. But this is an entirely different method of battling pests. A simplified explanation of the process, is where scientists introduce the gene from a particular strain of Bt insecticidal protein into the plant’s genetic material. The plant then manufactures that same insecticidal protein in its own growth process, directly from seed, as a natural defense against the target insect. The insect eats the plant, and dies. The genetic materials and proteins are regulated by the EPA, but the plant isn’t. This of course, makes it food for unending debate over what is truly ‘organic’ or ‘natural’, and what is not, with no definitive conclusion in sight. But it’s here as a huge portion of the agricultural community and it is not going away any time soon.

But wait, there’s more… More like the script in a ‘B’ science fiction movie, sex pheromone spraying may be the most controversial form of all pesticides. In a nutshell, aerial saturation-bombing of fields, orchards or just neighborhoods which are infested with a specific damaging insect, is performed. The insecticide is actually millions and millions of tiny time-release plastic micro-capsules. When they open, they release synthetic hormones which disrupt the mating cycle of the target insect, distracting it from its destructive behavior, while ending its ability to procreate.

Of course, since the insecticide is sprayed from above, it can also find it’s way to many of the people in the treated area as well. The practice is so new that there is serious concern for its risk to the human population in or near the area being treated. (Particular concern is focused on children, pregnant or nursing women, and people with respiratory and heart ailments, thereby affecting a large portion of the populous.) It’s never actually been tested in this fashion, but is none the less being used right now, and so it is technically, experimental.

Legal action has already been tried once in California and failed. But more suits are sure to follow as corporate lawyers, state’s attorneys, and private interest group law firms choose their sides and square off. Meanwhile, the actual research is being done in real-time, in the real world. Stay tuned…

On the practical side for the home gardener, there are a variety of natural items in the kitchen cupboard, which when combined, are also very effective natural pesticides. Garlic, onions, ginger, orange peel, and red pepper, are just a few of the ingredients, but may be all you need to keep your home garden in order. (along with the obligatory weeding). A quick web-search will produce websites that list recipes utilizing these pantry items as safe and effective alternatives to commercial pesticides.

Now, ‘organic’ doesn’t mean chemicals can’t be used. It means that only naturally occurring elements and chemicals are used. One of those pesticides is listed as ‘horticultural oil’. These are refined petroleum oils which when blended with water and other natural chemicals (because petroleum is naturally hydrophobic) can be sprayed on foliage. Basically, they coat the invaders and suffocate them, yet they don’t harm birds, pets, or humans.

So how do you know which pesticides are safer than others, organic or otherwise? There is a scientific formula called the Environmental Impact Quotient or EIQ , which measures numerous risk characteristics of pesticides. Some of those risk characteristics gauge the environmental impact on the soil, and water, as well as their threat to humans, pets, and wildlife, particularly bees, birds, and butterflies.

The interesting thing about the EIQ, is that it illuminates the fact that some organic pesticides are substantially more toxic and dangerous than other synthetic pesticides. The numbers, much like the formulas, won’t mean much to you unless you have a chemistry background. But one of the safer organic pesticides is Bt, coming in at around 13.5 and is regarded within the industry as ‘very safe’ (for what that’s worth). The ‘organic’ Rotenone and Sabadilla (remember, beans and lilies?) are considered seriously toxic in certain levels of exposure, (humans, pets, birds, fish and wildlife not withstanding). They are rated at 33.07 and 35.6 respectively, and are generally regarded as ‘last ditch effort’ pesticides. On the other hand, there is the synthetic pesticide, Carbaryl, known commercially as Sevin ™. Discovered and marketed in the 50’s by Union Carbide (of Bhopal infamy) and now owned by Bayer, it is a synthetic neurotoxin which is actually banned in the UK, Denmark, Sweden, Germany and Austria. The US EPA acknowledges its toxicity to humans, and also suspects it to be carcinogenic, but for some reason, won’t pull the trigger on banning it. However, it is rated right there in the middle at 22.6, and so that may be a contributing factor in their reasoning.

A more ‘consumer friendly’ way to gauge risk through toxicity of pesticides is to locate the ‘signal word’ on the safety area of the pesticide’s label.

The three signal words (in ascending order of serious risk) are:

  • Caution – the least toxic and dangerous.
  • Danger/Poison – the next level up.
  • Warning – the most toxic of the pesticides available.

The National Pesticide Information Center (NPIC) provides a chart that more clearly explains the levels of toxicity, which fall under each signal word heading. It is the product of a coordinated effort together with the Environmental Protection Agency (EPA). The abbreviations ‘LD’ and ‘LC’ stand for ‘Lethal Dose’ and ‘Lethal Concentration’, respectively. Category IV is legally considered ‘optional labeling’, at the discretion of the manufacturer. The key to understanding the chart is understanding that in this particular area of drug metabolism, Lethal Dose or Lethal Concentration is a measured by a result of 50% or more fatalities in animal testing after a single dose or time-limited exposure. The formula for LD is measured by milligrams of the substance being tested, relative to the body weight (in kilograms) of the test subject. The formula for LC is the ratio of the chemical in milligrams to the volume, either mobile phase or atmosphere (water, or air) measured in liters. The higher the level of a substance required to produce that 50% lethal dose rate, the lower it’s toxicity.

Signal Word Toxicity Categories

In Conclusion, the key misleading element, which is common to all of these pesticides and chemicals (both synthetic or organic), is the fact that the large majority of consumers feel that all are relatively safe because they are permitted to be sold on the market in the first place. The truth is, that the more research an educated consumer does regarding the efficacy vs toxicity of these pesticides, the more inclined they might be to hit the kitchen and start mixing up their own ‘safer’ pesticides comprised of peppers, garlic, orange oil, and other more inert ingredients. Your mileage may vary.


Be a Hero


Now is the Time

Blog - Local All Seasons

There are things we can do, as locavores, to make obtaining fresh, locally grown food much easier. Now is the time to consider a summer CSA program.[…]

Read more…


Spring Farm Guide

We would like to offer a free copy of our guide to your address! We have a limited amount we will be mailing so please email and reserve your copy today!

Learn more here!…

Local Food and Local Farms

Coffee: The Healthy Drug Addiction

I vividly recall like it was yesterday the time I had my first delicious cup of coffee. Rhode Island just got dumped on by the Blizzard of '78 and Salty Brine announced over the radio that there would obviously be no school today[…]

Read more…