Meet the Methyl Sisters

May 13, 2016 2 min read 1 Comment

Meet the Methyl Sisters

Who wants mold, fungi and bacteria growing in their dog's shampoo? Besides being gross, It isn't safe!

The more important question is: What price in terms of health and safety are you willing to pay to keep these microorganisms out?

Our focus is on two preservatives with really long names: Methylisothiazolinone (MIT or MI) and Methylchloroisothiazolinone (MCI). Given their long names, we often refer to them as the "Methyl Sisters". For some reason it makes sense to us as they are usually found together on ingredient labels!

MIT and MCI are synthetic preservatives within the chemical group called isothiazolinones. Isothiazolinones are "biocides" meaning they are used to control the growth of bacteria, fungi, and algae. You will commonly see MIT and MCI in water cooling systems, paint, wood preservation, non-alcohol anti-bacterial hand sanitizer, and anti-bacterial wipes as they are very effective at what they do.  

The US production of MIT began in about 1998. Early on these preservatives were lauded for their effectiveness. In light of recent safety studies, they are now being phased out of many products - especially those that have contact with skin. Canada, Japan, the European Scientific Committee on Consumer Safety, and Germany's Federal Institute for Risk Assessment have all restricted or banned MIT and MCI for use in human cosmetics and other products.

Why aren't MIT and MCI banned in dog grooming products? Well, there are no regulations for safety and security of pet grooming products. So, you have to be the watch dog! 

Methylisothiazolinone (MIT) is thought to be slightly more toxic than MCI. Studies have revealed that not only is MIT associated with allergic reactions and skin irritation issues, it is also a neurotoxin. Meaning, it can cause damage to the nervous system. MIT is also a classified ecotoxin - it does damage to the environment. 

Methylchloroisothiazolinone (MCI) has also been associated with allergic reactions and skin irritation. There is also mounting evidence to classify MCI as a possible mutagen (meaning it has links to cancer).  And, like MIT, it is a known ecotoxin - washing it down the drain can impact the health and safety of wildlife even after it passes through a water treatment facility. 

While MIT and MCI pose real risks for use, the elephant in the room is of course that these are relatively new synthetic preservatives with no long term health studies. Twenty years is not a long time to determine linkages between ingredients and health related issues. Yet, within the 20 years of use linkages have been made to allergic reactions, skin irritation, neurotoxicity, and cancer. 

We've used the word "synthetic" to make it very clear that these are not natural ingredients. They do not exist in nature but are synthesized through chemical reactions in a manufacturing facility. If you see these preservatives on dog grooming products that also make the claim "all natural" - that product is being greenwashed.

Greenwashing = marketing a product as "all natural" to make it sound like a safe non-toxic and all natural product when it is not. 

4-Legger's dog shampoos use rosemary extract, a naturally extracted powerful antioxidant, to serve as a preservative. It is safe, non-toxic, and has been used for hundreds of years!


1 Response

Stephanie Hayes
Stephanie Hayes

November 22, 2019

My dog Lucy started having seizures out of nowhere shortly after we changed cat litter. No matter how hard we try, she occasionally gets into the cat’s litter box. I mentioned this to the vet, but she did not seem to think this was the cause of Lucy’s seizures. Lucy had her first seizure, then 20 hours later a second, then three more 6 hours apart before we could get in to see the vet. The last two were not as severe, but still worrisome since they were coming six hours apart and I had no idea what was going on. The vet ruled out kidney, liver, and abdominal issues which left neuro, brain tumor, and toxins. Lucy stayed at the vet all day without any seizure activity and had no more seizures for the next few days. It was at this point that I was sure it was a toxin. She was on NexGard, which I had given her a few days prior to the seizure, so I thought it might have been that. Last night I caught her at the cat box for a split second and grabbed her before she could get much. I popped her on her nose and some cat litter spilled out of her mouth. Within 20 minutes her head started shaking as though she was having a Parkinson’s type tremor and she entered a post-ictal state. She could not focus and she slept all night long and most of the next day, barely rousable. I checked the ingredients on the cat litter and started googling them all and finally came across MIT. This has to be the culprit!. We have since decided to cut a cat door in the downstairs bathroom door and keep that door closed so she can’t get into the cat box and we will definitely be switching cat litter brands! I had no idea they would put such a poisonous substance in cat litter, especially since the main ingredient (bentonite) is supposedly healthy for dogs. Crazy!

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