Why Was Chlordane So Good?

At a past Industry meeting someone asked the question above. With the chlorinated hydrocarbons gone for over thirty years now, the majority of today’s pest professionals have probably never enjoyed the use or even the smell of good ole C-100 (chlordane) and/or any of it’s cousins Aldrin, Dieldrin or Heptachlor, we all used back in the day. But seriously, why was that stuff so good and why do we tend to remember it as being the best?

Firstly, let’s remember that C-100, aka Chlordane, was what we manufacturer type folks called “An Eight Pound Product”. This means that there was 8 lbs of Active Ingredient in each gallon of concentrate. The formulation was 72% active ingredient. You can find these labels online to see that this is correct.

Reading and following the label directions had us applying the mixed Chlordane termiticide solution at a concentration of 1.0%. Compare that with today’s popular termiticide products which are applied at about 0.06% solution and we can see that the differences in the concentration applied is significant. In fact, it’s a huge difference.

Applied at 1.0% we were pumping 10,000 parts per million of Chlordane around and beneath our customer’s homes each day we did a liquid termite application job. At 0.06% with today’s popular liquid termiticides, we’re applying just 600 parts per million. With Chlordane, we were applying nearly seventeen times as much active ingredient. Clearly 10,000 ppm vs only 600 ppm is a huge difference. At 1.0% termite professionals of the past were applying nearly seventeen times the amount of active ingredient as is done today.

One of the reasons Chlordane was considered a great product was also one of the reasons the industry no longer has it available for use today and it was banned; it’s persistence in the soil post application. Simply stated, Chlordane, and other chlorinated hydrocarbon pesticides, lasted a long time in the soil. The half-life of Chlordane was many times that of today’s termiticide active ingredients. Those interested in knowing and/or learning the active ingredient half-life data can search online.

Another factor which contributed to the successful efficacy of Chlordane was that it was considered to be a non-repellent type termiticide product. Once applied and dry, termites would attempt to tunnel through Chlordane treated soil. Similarly, today’s most popular termiticides are also considered to be non-repellent.

Note that some knowledgeable industry insider type folks will tell you that Chlordane was applied at about 10 times the needed dose that was actually needed for it to be effective. In a recent telephone conversation on this subject a notable industry insider commented that “. . . they wanted to have a one hundred times the efficacy factor for termites . . .” Simply stated, we applied many times the necessary quantity of Chlordane needed to successfully stop the termites.

So, let’s think about this in the proper perspective. Imagine if you applied either Termidor (fipronil) or Premise (imidacloprid) termiticides at about seventeen times the current labeled rate. If we were able to do that legally in accordance with the product label directions and State regulations, it would likely yield superior, if not fantastic, results.

If we consider all these factors we might conclude that overall, Chlordane was really not as magical as we might remember. Imagine applying any of today’s products at ten or more times the labeled rates. They’d probably work very well too.

Of course, product cost is always a consideration. By today’s standards Chlordane was literally cheap. Back in the day it cost about $15 per gallon and you’d mix one gallon with about 99 gals of water to make 100 gals of solution for a treatment cost of about fifteen cents per gallon. At the time of this writing, the cost to make 25 gallons of Termidor is about seventy-five dollars. Therefore, using it at seventeen times the label rate would be costly.

Was Chlordane really great?  I suppose the answer to that question is, Yes and No. However, it also depends upon how you look at it. For those of us who used it back in the 70s and 80s, I’ll bet you remember mimicking that popular movie line by saying: “I love the smell of Chordane in the morning . . .”