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What Matters Most in a Pesticide: Active or Inert Ingredients?

Active or Inert Ingredients in Pesticides

What are we looking for in a pesticide?

Bugs show up. We want them gone. Usually yesterday. So we do a little research online, find some pest control products with some positive reviews, and look to see what it is that makes them effective. Before long, we discover that all pesticides contain an Active Ingredient (AI) which is the key ingredient that does the actual killing or repelling or eliminating of the pests. This Active Ingredient, we discover, is visibly included on all pesticide product labels. We then look around for other pest control products with the same active ingredient, find the best deal, make the purchase, and wait for our agent of death to arrive. 

But what information did we really use to make our buying decision? How much does the Active Ingredient actually matter? Well, it does certainly matter. The AI lets us know how we should expect the product to specifically impact target pest organisms. The more we know about this mode of action, the better prepared we will be to apply the product in a manner that facilitates effective pest elimination. But it also definitely isn't all that matters. 

The "AI" is Often Only a Tiny Part of a Pesticide...

Did you know that in many instances, the active ingredient of a pesticide is a small fraction of one percent of the total composition of the product? In both Combat Max and Maxforce FC Ant Gel Baits, for instance, the Active Ingredient, Fipronil, is only .001% of the overall product. At just a glance, these 2 products might appear to be the same, as they both contain the same amount of the same active ingredient. But what we don't know is what similarities, if any, exist amongst the other 99.999% of the ingredients within each product...the "Inert Ingredients." 

As you might expect, the inert ingredients are all the ingredients in a pesticide other than the active ingredient. And these ingredients are the ones that largely determine the product's sustainability, applicability, practicality, solubility, and manner other factors that will ultimately determine to what extent target pests are likely to be exposed to the active ingredient. The active ingredient becomes inconsequential if the pesticide isn't formulated in a way that allows for optimal exposure, and it is these inert ingredients that are responsible for that formulation. 

So Which Part of a Pesticide is Most Important? 

The takeaway here is this: both the Active Ingredient and the Inert (Other) Ingredients are essential to how effective a pesticide is likely to be under certain environmental conditions. The Active Ingredient lets us know how a given pesticide is likely to impact various pest populations, and the Inert Ingredients determine how the pest populations are likely to come in contact with it. 

But There's a Snag...

Unlike the disclosure requirement for active ingredients, which must be specifically identified on the product label along with the concentration, pesticide manufacturers need not disclose the specific nature of the inert ingredients, other than what percentage of the product they comprise. So while we are able to know and compare active ingredients, we have no way of comparing the other ingredients which make up almost the entirety of the some cases as much as 99.999%. 

So What Should We Do?

As a starting point, consider which products professional exterminators use and recommend. If the less expensive pesticides sold over-the-counter at your local hardware store provided the same level of effectiveness as professional-grade products with the same or similar active ingredients, the professionals would most certainly be using them. So probably, in many instances, other products are likely to be more effective, in many situations, under many sets of circumstances. And these differences in effectiveness are typically discovered through direct experience using many pesticides over an extended period of time. 

When comparing pesticide products, focus on reviews and recommendations from professionals that are limited to the specific pest species you are dealing with. Just because 1,000 people say a certain product works great for "ants," for instance, won't necessarily mean that product will work well for your particular species of ant in your particular environment. In the world of pest control, experience goes a long way. 

Still have more questions about active ingredients? Professor Pest's Live Online Chat provides free online support to help you make well-informed decisions about your pest control efforts. 

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