UT Extension News: Natural Doesn’t Mean Safe

May 27, 2022

It seems I get more questions and hear more comments each year from individuals who want to do things on the farm or in the garden “naturally.” Mostly, they come from well-meaning individuals who are concerned about toxic pesticides, synthetic fertilizers, and genetically modified crops. I’m afraid sometimes we equate “natural” with “safe” and that is not necessarily the case.

Take pesticides for example. There are some pesticides that are manmade; we call those synthetic. Others are made from chemicals that occur in nature; we often refer to those as organic. What they both have in common is the potential to harm living organisms.

It seems to be a common belief that natural pesticides are safer for the environment and the applicator that synthetic pesticides, but while this belief is common, it is not necessarily true. For example, here are a few “natural” chemicals that are far from harmless:

Ricin – One of the products obtained from the castor bean plant is castor oil, which is used commercially and for human consumption. However, another component of this plant is ricin, one of the deadliest naturally occurring poisons known. But hey, it’s natural!

Strychnine – This toxic alkaloid is derived from the seeds of trees that can be found in India, southern Asia, northern Australia, and Hawaii. It has been widely used in baits to kill rodents and other mammals and is a common adulterant of many illicit drugs. It has also been implicated in many murders since exposure to this natural chemical in high dosage can be fatal.

Arsenic – Here is one we learned about in chemistry class, with the symbol As. According to the World Health Organization, “Arsenic is a natural component of the earth’s crust and is widely distributed throughout the environment in the air, water, and land. It is highly toxic in its inorganic form.” This natural chemical is a confirmed carcinogen and has also been used in the past as a pesticide.

The point of all this is not to criticize those who want to make sure they aren’t harming the environment or themselves by how they grow and protect their crops. On the contrary, I am right there with you. What I want you to understand is that whether you choose a naturally occurring chemical or one that was man-made, pesticides are designed to kill living things and should be used with caution in accordance with the labeled directions.

All pesticide labels, both synthetic and natural, include signal words that specify the toxicity of the product. CAUTION means low toxicity, WARNING means moderately toxic, and DANGER means highly toxic. When selecting a pesticide, these signal words along with other wording on the label can give you an idea of the safety of the product.

It may be that a synthetic pesticide you apply once or twice during the season has less of an environmental impact that an organic pesticide that must be applied several times to be effective. On the other hand, organic pesticides may provide an effective, less toxic alternative in certain situations. For help with selecting a pesticide, contact the UT Extension office at 615-735-2900, or check out our library of publications at smith.tennessee.edu.