Are Organic Pesticides Always Safer?
Organic is an often misunderstood term. Here’s Bill DeBoer to help clear a few things up.
“I don’t use chemicals, I grow organically!” This is a reoccurring message continuously articulated by a certain sect of organic growers or consumers of organic products. It also shows that there is a preponderance of misinformation and a lack of understanding.
Everything is a chemical, including those organics derived from natural origins. What these people are trying to say they choose a more natural choice when growing organically (as opposed to the negatively-perceived synthetic counterpart).
However, the point of this article is not to draw negative criticism toward organics, but rather address misconceptions in an effort to help you make sounder, more-informed decisions. So, whether you are grounded in either organics or synthetics, you need to internally digest the following concepts. (Note: when I use the term organic in the article, I am referring to chemicals derived from natural origins.)
Are organics always safer than synthetics? No. People have bought into the premise that anything natural is safer. The natural state of a chemical inherently does not dictate safety.
For example, imagine organically growing the castor plant (Ricinus communis). From this you could exact a very powerful compound—ricin—which is highly toxic to mammals. While this example is meant to be impractical, the concept is not: natural chemicals can be just as deadly as synthetic ones.
Have you ever looked at the chemical compounds found in organic pesticides or the LD50 (lethal dose inducing mortality in 50% of test population) value? Remember, toxicity is a function of the exposure time as well as the dose/concentration.
Simple chemicals that are regarded as harmless can be very toxic if the concentration is high or the exposure time is long—for example, water is toxic if consumption continuously exceeds 1.5 L (0.4 gal.) per hour.
Safety is at the forefront for organic growers and consumers of organic products, but have you ever looked at the signal word (i.e. caution, warning or danger) on the chemical label? By human nature, we will believe something without questioning the validity if enough people say it is true.
There is a reason marketing people can receive hefty salaries: thanks to them, safety has become unanimous with organics. Funny, since federal regulation uses the same wording for organic pesticides?
It is important to note that organics generally have a significant advantage to synthetic counterparts. The half-life, or breakdown, of organic compounds tends to be on average quicker than synthetic chemicals, whose half-life can be long and breakdown is slow (thus the persistence in the environment is longer).
However, while organic pesticides can breakdown quickly, their effect is often short lived and frequent applications are more necessary in comparison to synthetic pesticides. Thus, an individual must always understand the type of chemical, application, frequency, concentration and relative persistence.
After all, at face value, what appears to be more toxic: compound A applied once or compound B applied six times in the same time span? Obviously, more information is needed.
Another critical consideration is dismissing linear thought processes. Just because a compound is organic and targets one type of pests, it does mean it will not cause alternative problems.
For instance rotenone, a very effective organic pesticide for certain beetles and caterpillars, is also highly toxic to aquatic life. Therefore, you must avoid spraying around any body of water. Another example is nicotine, which causes paralysis to pest insects and is readily absorbed by the skin of mammals—and it is quite toxic! Lastly, pyrethrins are highly effective at eradicating a wide range of pests, but they are also toxic to helpful pollinators like honeybees.
As growers and gardeners, we cannot think our actions are singular or linear. When using both synthetic and organic chemicals, our actions have direct and sometimes irreversible consequences.
Always research the active ingredient prior to use, as well as proper protective equipment, relative toxicity and susceptible population (which can range from helpful insects to people).
A study published in 2006 proposed an interesting hypothesis that microbial (bacterial and fungal) contamination, not pesticide residue, is of larger concern to public health. It begs the question, are organically-raised fruits and vegetables less likely or more likely to have microbial growth due to pesticide practices? I don’t have the answer, but it is an intriguing point nonetheless.
Another important component to this review was the difference in detection of synthetic and organic pesticide residue. A 10-year trend line by Baker et al. showed a significant increase in the detection of synthetic pesticide residue relative to that of organic pesticide. One of the main points was organically treated fruits and vegetables still had detectable pesticide (albeit organic) residue.
Ultimately, there is not enough information to make definitive statements on overall safety, which is compounded by the fact that sampling methods are not always accurate. However, it does show we cannot think of most organic produce as “chemical free.”
In conclusion, practices involving chemicals that have a low environmental persistence, are effective toward the target pest and have a low risk factor towards the consumer should be our future goal.
If human and environmental health is the chief concern for organic growers, then knowledge is the strongest ally. I have been and will always be an advocate for the safest and healthiest option of growing produce. This article should not be viewed as anti-organic, but rather as pro-education.
Consumers should have all the facts so they can make an informed decision. For more information on mode of action and relative toxicity of organic pesticides, refer to the Oregon State Extension publication Least Toxic Organic Pesticides for Gardeners (pdf). If you remember nothing of this article, retain these points to ponder:
- Everything is a chemical and everything can be toxic if the right dose or exposure time is met.
- Read the label, and ask questions when you are unsure.
- Organic does not equate to safe just as synthetic doesn’t represent unsafe.
- Actions have consequences and application of pesticides, even organic ones, can have a negative impact on organisms from fish to bees to humans.
- There are pros and cons that an individual must weigh when selecting a pesticide, organic or synthetic (i.e. cost, effectiveness, relative toxicity, etc).