In part one of this article, we introduced the issue of sorting out the difference between simulants, pseudo and “real” odor in detection training.
Continuing to assist in our further understanding, we can classify simulants into four categories, and hopefully you will see how real samples, simulants, and pseudo are related.
What we call “real” training aids are just samples of the whole material itself — using small amounts of things like C4, TNT, and street cocaine are all “real” training aids.
Four Types of Simulants
Simulant training aids are designed to mimic or possess properties of the real material, and there are four types:
• Type 1 simulant: Presents the odor picture of the active ingredient
• Type 2 simulant: Presents the odor picture of a byproduct or impurity
• Type 3 simulant: Presents the odor picture of a filler or additive
• Type 4 simulant: Mimics the odor of the material of interest using alternate chemicals in hopes to produce a similar odor. This is what we call a “pseudo” scent
What’s of special interest here is that a Type 1 simulant isolates the active ingredient of interest, so you could say you are presenting the dog with the purest form of the odor you want the dog to detect.
Compare that to the “real” training aid, which has a lot of other odors in the vapor, some of which may be stronger than the active ingredient. These other odors coming from the byproducts and fillers are part of the odor picture the dog smells.
One could argue that a Type 1 simulant is better than the “real” because it removes all these other odors.
But those of us who train dogs know that a dog trained on this pure odor could have trouble when presented with the pure odor in a soup of other odors.
Continually rewarding the dog on the soup of odor around the real scent will reinforce the dog’s response to the soup of odors. Just training on the simulant is not enough – it’s important in maintenance training to place out distractor odors that are commonly found in fillers or byproducts.
Two Examples: Cocaine and C4
Let’s take street cocaine and look at possible simulants. To make a Type 1 simulant for cocaine, we would need to capture the active ingredient in street cocaine (benzoylmethylecgonine, or pure cocaine). But cocaine is a local anesthetic and likely numbs the membranes in a dog’s nose, making it a poor choice for a Type 1 simulant.
A Type 2 simulant could be one of the many byproducts of cocaine’s decomposition such as methyl benzoate, for example.
Methyl benzoate is in fact the most common form of cocaine simulant. Were we to pick a Type 3 simulant, it would be baking soda, mannitol, or sugars.
These things are commonly found in the world and are thus a poor indicator of the presence of cocaine because of their commonality. The thing we commonly refer to as cocaine pseudo is actually a simulant.
Let’s look at another example, C4. To make a Type 1 simulant, we would have to capture the odor of the active ingredient, RDX, at a low enough vapor pressure that it is not possible for it to explode.
This is the strategy of simulants like NESTT and TrueScent for C4. To make a Type 2 simulant, we could use the chemical we identified as “hexamine” but that is found in other products like solid fuels.
To make a Type 3 simulant, we could choose one of many fillers/additives such as one of the binders or plasticizers, but these chemicals are even more commonly found in motor oils and some brake fluids.
A Type 4 simulant would be an “alternative or substitute chemical.” The difficulty here is that unlike a Type 1, 2, or 3 simulant, a Type 4 simulant is often a patent protected (and unidentified) pseudo that is manufactured to “smell like” C4 or RDX or whatever it is mimicking.
Therefore you are training your dog on a chemical that is supposed to “smell like” the compound you are interested in, but there is no scientific evidence for what “smell like” actually is. In most cases these alternative chemicals are unknown to you, and this is why I don’t recommend using a true pseudo scent.
My Personal Recommendations
In my opinion, you should not train your dog on an unknown substance, just because the manufacturer of the product says you should. Type 1-3 simulants are manufactured with known chemicals which are either the active ingredient or some ancillary ingredient found in the compound.
It is commonly accepted among research chemists in the field that Type 4 simulants or true Pseudo chemicals have no peer-reviewed scientific research to show their effectiveness.
Until the manufacturer of the pseudo scent is able to provide you with the information about what is in the pseudo scent, you will not know what you are training your dog on, nor will you know how the manufacturer determined that it “smells like” the target odor or real compound you are trying to locate.
Type 1 through 3 simulants have something to do with the compound in question, directly, where the Type 4 simulant does not, necessarily.
Further research needs to be done on claims that some small amounts of pseudo mimic the scent picture of large amounts of the “real” odor. There are few if any studies on how much of a simulant or pseudo corresponds proportionally to the weight of a “real” sample, or for that matter, how much set time is required for the pseudo to achieve the scent picture of a given weight of “real” sample. There are a lot of questions to answer.
Re, Michael, Ph.D. The Mystery Behind K-9 Scent Training Aids. Presentation given at the K-9 Cop Magazine Police & Military Working Dog Conference, Nashville TN, September 30 – October 3, 2012.
Special thanks to Michael Re Ph.D. of Signature Science LLC for providing me with research material and proofreading the science in this article. Signature Science LLC manufactures TrueScent™ which are type 1 simulant K-9 Training Aids.