Pesticides: Now You Know!

Have you ever ask yourself, "Why are chemical pesticides bad?" This article will explain exactly why pesticides are approved for use on fruit and vegetable crops and why you should avoid them.

Let's start by answering a few questions.

First, what is a pesticide? 

A pesticide is a product used to eliminate any organism deemed undesirable by the user of that product. 

Pesticides can be categorized as selective or non-selective. Selective pesticides are designed to target a specific organism or group of organisms. For example, Bacillus thurngensis (Bt) is a selective pesticide designed to target the larva of Lepidoptera, also known as caterpillars. Non-selective pesticides are a bit more general in what they kill, for example Roundup is a non-selective herbicide and will kill all vegetation. Except genetically modified organisms of course, but that is different subject to be discussed on a different day.

Pear Slugs on Cherry Leaf

"Pesticide" is a general term and  includes, but is not limited to the following:

Insecticides

Herbicides

Fungicides

Miteicides

Aracnicides

Rodenticides

Molluscisides

Each of the above list is developed to target a specific type of living organism. For example insecticides target insects and herbicides target vegetation. Obviously none of these pesticides target humans, but are they harmful to us?

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Are Pesticides Harmful to Humans?

Now, the real challenge. How can you tell if a pesticide is harmful to humans? Well, none of the pesticides are tested on humans. Who would volunteer for such a thing? But let's stop and think about it. Every time you bite into produce, chances are you are part of the study that will determine whether or not pesticides will be used in the future. We will discuss that thought later, but think about it for a moment.

Pesticides are measured to see how toxic they are before they are approved for use in the garden or in agriculture on fruit and vegetable crops. 

How do you measure a pesticide's toxicity? 

Let me explain. Toxicity is measured using a scale called "LD50". Which is short for "Lethal Dose of 50 Percent of the Target Population". Or in other words, how much product is required to kill half of the organisms that are exposed to it? LD50 is measured in mg/kg of body weight, so the lower the number, or the smaller the dose, the more toxic the substance is. 

There are a few problems with this method. What is the target population? How is the pesticide administered? and is it administered all at once or in small incremental doses over time?

Let's answer each of those questions now.

What is the target population used to test a pesticide's toxicity? 

Well it could be anything. If it's an insecticide, it might be insects, like cockroaches or grass hoppers. If it's an herbicide it might be purslane or field bindweed. But that doesn't really help us does it? We need to know what the toxicity is to humans. In the world of science, the closest thing to a human is a mouse, or a rat. Humans and rodents aren't exactly the same, but we are both mammals... I guess that will do. And try to find a chemical pesticide that claims to not use animal testing.

Mice and Rats are Used to Test Toxicity

How is the pesticide administered to the tests subjects? 

Well, LD50 can be measured in many ways, the most common are as follows:

• oral
• dermal
• inhalant

Oral is when pesticides are ingested by the test subject. Dermal is when a pesticide is applied to the test subject’s skin. Inhalant is when the pesticide is misted in the air and the test subject is allowed to breath in the particles. As you can probably predict, each test will result in a different outcome. A pesticide might be more toxic ingested, for example, than if applied to the skin.

What are the effects of pesticides on an organism short term versus long term? 

Most studies are done to find out the "acute toxicity" of a pesticide. Acute toxicity is short term exposure and usually tests an organisms ability to metabolize or filter the toxins from its body. High concentrations of the pesticide are administered to an organism to test at what point their exposure to the pesticide is fatal.

But what if small doses of pesticides are administered over a long period of time? Long term affects of a pesticide administered to an organism is done to test “chronic toxicity”. Unfortunately there are few studies that demonstrate what the chronic affect of pesticides are after long term exposure to the chemicals.

Review

Let’s review. Pesticides are toxic. Obviously. They're designed to kill pests. But toxicity is relevant. Some pesticides are more toxic to some organisms than they are to others, pesticides are more or less toxic based on how an organism is exposed to it, and the concentration and the duration of the exposure will also change how it affects an organism.

Why are Pesticides Approved by the Food and Drug Administration?

Pesticides have very strict regulations and in order to be approved by the FDA, pesticides must be used according to the instructions on the label. If you grab a bottle of pesticide and read the label you will see that there are very detailed instructions on how to apply it, where to apply it, and at what concentration. The label will also give you safety instructions like how to protect your skin and eyes and what to do in case of an emergency.

When you use a pesticide according to the label you will find that the active ingredient is a small percentage of the overall concentration and the concentration is usually diluted further before it is applied. In addition to the low concentration, most pesticides are broken down by UV light. Long term exposure of the pesticide to the sun is the best way to ensure that a pesticides is less toxic to any organism that ingests it. That’s why one of the most important instructions on a pesticide label is the time that you should wait between the last application and the harvest.

Below is a list of chemicals with their associated LD50.

Toxicity depends on the dose

As you review the chart in the previous section you will see that too much water and too much salt can be toxic to living organisms.

How much pesticide is found in our food?

So if pesticides are applied to fruit and vegetable crops at ultra low doses and the pesticide is allowed to break down in the sun before it is harvested, what’s the big deal? Nothing. It's not really a big deal, it's the compound of really small deals that add to a big deal. 

Pesticides Will Break Down in the Sun

Active Ingredients vs Synergists, Adjuvants, and Carriers

Look at a bottle of pesticide and you will see that the active ingredient is a very small percentage of the overall contents in the bottle. So what else is in there? Good question! Nobody really knows, but the other 99% of the contents found in a bottle of pesticide can be broken down into three parts.

First, synergists are chemicals that may or may not have a significant toxicity, but when added to the active ingredient it will synergize with it, making it more effective. One such synergist is piperonyl butoxide a compound that inhibits a living organism's ability to break down or filter the active ingredients in pesticides making it more toxic. A synergist by it's self may not have a significant toxicity.

Second, adjuvants are chemicals that, again, may or may not have a significant toxicity, but these chemicals aid in the application of the active ingredient, also allowing it to be more effective. For example adjuvants will allow oil based ingredients to dissolve in water or will break down the surface tension of water so that the product will spread over the target organism instead of bead up on the surface.

Lastly, Carriers are typically inert ingredients that help carry the active ingredient to the desired location. Water is probably the most common carrier, but some pesticides might consist of chemically treated sand. Sand being the carrier.

When you look at a bottle of pesticide and research the active ingredient, you can easily find the toxicity of that one ingredient. But what about the toxicity of the active ingredient in combination with all of the other ingredients? This, you will find is much more difficult to research.

Ok, so let's say you find the toxicity of a pesticide with all of it's synergists, adjuvants, and carriers. You might realize that the washing machine detergent you use on your cloths has a higher toxicity than the pesticides. Chances are it does have a higher toxicity. So why do you use it? Well, it washes all the dirt, oil and germs away and then it's double rinsed. Yeah, but can you still smell it after it's been double rinsed? The answer is YES. That means there is a residue left behind. Is the residue toxic? Probably. Probably not very much.

Well, consider this scenario. You wake up in the morning, you brush your teeth with chemicals, you take a shower with chemicals, you put on clothes cleaned with chemicals, you eat your breakfast that has chemicals on a plate that was washed with chemicals, you drive a car to work along side hundreds, maybe thousands of commuters burning chemicals and discharging the exhaust into the air that you are breathing. It's only 8:00 AM and you have already been bombarded with chemicals. I'm not trying to scare you or make you paranoid about chemicals, I'm just trying to put pesticides into perspective with all of the other toxins that we are surrounded with 24/7. Pesticides are relatively insignificant if you compare them to all of the other toxins around us.

Would eliminating pesticides from our life make us healthier? Probably a little. Would eliminating all toxins from our life make us even healthier? Probably a little more. You decide.

Is Eating Organic Better?

In the following blog post we will discuss the real dangers of pesticides and why they should be avoided.

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