Wednesday, July 18, 2012

Methylchloroisothiazolinone and Methylisothiazolinone: Why 'Paraben Free' Means Nothing to Me

Methylchloroisothiazolinone and Methylisothiazolinone.

Try to say those three times fast.


Are these chemicals as bad as they sound like they might be?


According to this site (and tons of others--even unbiased sites that aren't trying to sell something), both of these chemicals are preservatives. They are also known to be strong allergens.

Additionally, they're becoming something I'm seeing more and more of on product labels, especially since the paraben-free craze began a couple years ago.

Methylchloroisothiazolinone and Methylisothiazolinone are alternatives to parabens, which are also preservatives. I assume companies started using them because the word "paraben" was becoming so recognizable as a detrimental ingredient. As people started avoiding products with parabens, my guess is companies started developing products with Methylchloroisothiazolinone and Methylisothiazolinone as unrecognizable alternatives so they could stamp "paraben free" on their labels and win back health-conscious consumers.

The chemical structure of Methylchloroisothiazolinone

Let's head on over to the Environmental Working Group's Skin Deep Cosmetic Safety Database to get a little more information...

Here are the scores for the parabens:
Methylparaben = 5
Butylparaben = 6
Propylparaben = 6

Remember, on this scale of 0-10 a 10 is the worst. These chemicals are in the mid-to-high range, which, I guess, might not seem bad to some people, but these are often used in combination. More than one of them will show up on one product's ingredients list. So yeah... that concerns me and those who think like I do.

But this entry isn't about parabens, so let me move on.

Here are the scores for these hard-to-pronounce alternatives:
Methylchloroisothiazolinone = 6
Methylisothiazolinone = 6

Guess what! These two aren't just allergens. Methylchloroisothiazolinone is also linked to cancer, immune system toxicity, and asthma. Methylisothiazolinone has ties to immune system toxicity and neurotoxicity.

Yes, the parabens, if you look them up, are just as bad--maybe worse (they also are linked to developmental/reproductive toxicity, organ system toxicity, and endocrine disruption)--but in my mind they're near enough to comparable. Usually I'll be the first to say "some change is good change", but in this case I don't think that's true and I intend to go out of my way to avoid them as much as I do to avoid parabens.

Methylchloroisothiazolinone and Methylisothiazolinone are definitely on my no-no list.

(This article was originally posted on my old blog, Glamoursaurus Goes Natural, which is now defunct.)


  1. i think i should be posting this on my fb..

  2. But it IS better than parabens.

    1. Please refer to the part where I said "the parabens, if you look them up, are just as bad--maybe worse". I did already say that these ingredients may be "better" than parabens. Though the Cosmetics Safety Database, which collects testing data rates them comparably on the scale, so I'm not so sure about "better" or worse. That's like saying, "Which poison should I use to kill myself, arsenic or strychnine?" Both poisons are deadly, just like both parabens and these paraben alternatives have ties to health concerns. My point is still valid, with or without bringing parabens in. These chemicals are linked to health problems (allergies, asthma, etc.) that most people would likely want to avoid. I'm not judging my readers for using products with such ingredients. (Read about the makeup brands I love the most--trust me I'm not judging anyone! Haha!) All I'm doing here is presenting the information that's available in a digestible format so people are able to make their own decisions about what they want to do. Thanks for reading and for contributing a comment!

  3. The bacteria that can happen in these products without a preservative is more dangerous, its impossible to make a product without a preservative that contains water/aqua. Do your research before posting this.

    1. I have done my research. There are many safer preservatives that can be used, many of which are natural and safer that would preserve various products just fine for the amount of time they realistically sit on our shelves. Many products we use that have these harmful ingredients in them don't actually require them. Take face washes, for example. A bottle of face wash isn't going to last someone who washes their face regularly very long. My Burt's Bees face cleanser without parabens or similar preservatives does not go rancid before it gets used up. It is unnecessary to include these ingredients when the products they're being put in don't really require lengthy shelf lives and are things we'd use up long before they went bad.

      I know from my research that what you said about products containing water needing preservatives is true. (I can--and do--read, after all.) This is mostly true in cases where one plans to store a product for a significant amount of time. But again, there are alternatives to the ones discussed in this blog entry that would have less ties to health concerns.

      On that note, each to their own. You do your thing and people who would like to avoid these ingredients can do their thing.

  4. I am sooooooo allergic to Methylchloroisothiazolinone and Methylisothiazolinone took years to find out what was causing my contact dermatitis outbursts... the past 3 years have been the worst.....only to find out about these preservatives in almost everything in the workplace and at home...the only cure is to stay away from the product....but how could I at work? getting swollen eyes and dermatitis so bad that I couldn't see. preservatives in cleaning products glues paper toner ink I could go on and on. out sick since February 2014, and in 4 months not one outbreak...........connection:.i seriously think so....and why doesn't the FDA stop the production of this preservative in products....I have no idea...Japan a very intelligent country has banned this product and other countries are following suit....and some products are not listing on the indregient list instead you will see aka names such as FRAGRENCE and MCI/MI get the message....we have to ask the FDA to reconsider this chemical in products exposed to humans....oh by the way, the answer as by companies using it...saying that if it is washed off thoroughly there should not be any harm....we what about CONSERVING WATER????? isn't that our most precious commodity....WTH....somethings gotta give here....