CMV - Methylisothiazolinone preservatives are safe for rinse-off products

PerryPerry Administrator, Professional Chemist
I know this ingredient is much maligned. And for good reason, as some people certainly have a bad reaction to it. But it seems like taking an objective view of all the available toxicological data, one can only conclude that it is safe for use.

The CIR did exactly this and concluded Methylisothizolinone preservatives are safe for rinse off products and for leave-on products formulated to be non sensitizing.

Here's their published report.

What convinces you that they are wrong?

Comments

  • BelassiBelassi Member, PCF student
    edited September 2020
    What convinces me? My two dogs. Other people's dogs. My own hands (Blumen liquid soap). Huge numbers of consumer complaints. Consumer groups campaigning against it. There's another member here who is being damaged by it. Is that not enough?
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • PerryPerry Administrator, Professional Chemist
    @Belassi - you're certainly not alone in having experienced negative reactions. I agree that for people who do have bad reactions to it, it is an ingredient they should avoid. I haven't seen any data on dogs but don't doubt that it could be a problem.

    However, people have reactions to all kinds of raw materials used in cosmetics.  For example, SLS, glucosides, organic acids, plant extracts, etc.

    What is the criteria by which we decide when a reaction effects enough people that the ingredient is banned from products?

  • BelassiBelassi Member, PCF student
    What is the criteria by which we decide when a reaction effects enough people that the ingredient is banned from products?
     - In my opinion commercial interests. They like it because it is incredibly cheap.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • BelassiBelassi Member, PCF student
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • BelassiBelassi Member, PCF student
    edited September 2020
    What dermatologists say.
    The first cases of ACD to MCI/MI were reported in 1985 from cosmetic use, marking the beginning of the first epidemic to isothiazolinones. In 1988, de Groot and colleagues reported on the significant ingredients responsible for allergy to cosmetics. In the 119 patients with cosmetic-related contact dermatitis, 56.3% were associated with skincare products. They also found that preservatives were most frequently implicated (32.0%), followed by fragrances (26.5%) and emulsifiers (14.3%). The most significant cosmetic allergen was Kathon CG, (a preservative system containing, as active ingredients, a mixture of MCI and MI) reacting in 33 patients (27.7%). Within 6 months de Groot and Herxheimer published another study on a significant number of the cases of Kathon CG (MCI/MI) allergy caused by products of the “leave-on” variety (eg, moisturizing creams) and stated that an epidemic had begun.

    - a SAFE preservative? I think not.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • PerryPerry Administrator, Professional Chemist
    I am not a toxicologist so I defer to the judgement of toxicologists when it comes to ingredient safety.

    The toxicologists on the Cosmetic Ingredient Review board (CIR) presumably would know about this and all subsequent studies. If the ingredient was unsafe as a preservative, why would an independent group of scientists conclude that it was safe?
  • BelassiBelassi Member, PCF student
    Thalidomide was regarded as safe until thousands of malformed babies were born. I suggest that the actual evidence is that the preservative is unsafe.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • PerryPerry Administrator, Professional Chemist
    edited September 2020
    There are certainly cases of people being wrong about drugs.  I will note that in the US, the FDA never approve Thalidomided due to safety concerns.

    What evidence is missing from the CIR report?  These are controlled studies which are the same types of studies run on most other cosmetic ingredients to prove safety.
  • PharmaPharma Member, Pharmacist
    Perry said:
    ...What evidence is missing from the CIR report?...
    The fact that these are extremely widespread and found in up to every second product of everyday life, not just cleaning detergents, paints and insulations but a majority of everything which, at one point during its production, came into contact with water or needed some protection against microbes does contain at least traces.
    It's one of the most efficient and cheapest preservatives for everything and therefore used and produced in insane quantities worldwide and that's the problem. It's everywhere whether you want it or not. Obviously, this dramatically increases sensitisation prevalence reaching now, depending on the publication, about 0.1% of the population being allergic to MIT and ~2% to CMIT, respectively.
    Furthermore, your report doesn't mention the ban of MIT/CMIT in leave-on cosmetics in Canada and EU (I didn't double-check to verify). It also doesn't mention that since that ban, prevalence of isothiazolinone allergies were declining.
    The two links do mention high assimilation of applied product and state a long half-life. That stuff accumulates badly with its t1/2 of about 2 weeks. However, others found different levels of assimilation and excretion times of a few days whilst others failed to measure considerable blood levels... it's a mess.
    HERE an EU report.
  • PerryPerry Administrator, Professional Chemist
    @Pharma - it's not banned in leave-on in Canada as far as I could tell. https://cosmeticsinfo.org/ingredient/methylisothiazolinone-and-methylchloroisothiazolinone  Chemicals get banned from products more for political reasons than for scientific reasons. I wouldn't expect a report on product safety to talk about the politics of the ingredient.

    The EU conclusion seems to support the use of the ingredient.  What am I missing?

    "On the basis of the data submitted, the SCCS is of the opinion that the mixture of 5-chloro2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one in a ratio of 3:1 does not pose a risk to the health of the consumer when used as a preservative up to a maximum authorised concentration of 0.0015 % in rinse-off cosmetic products, apart from its sensitising potential.
  • BelassiBelassi Member, PCF student
    apart from its sensitising potential.
    Cosmetic Brand Creation. Concept to name to IMPI search to logo and brand registration. In-house graphic design inc. Pantone specs. Cosmetic label and box design & graphics.
  • PerryPerry Administrator, Professional Chemist
    True, however you can say that of lots of ingredients.
    I didn't verify all of these but assuming this is mostly valid, there are a lot of ingredients with sensitizing potential.
    https://www.paulaschoice.com/ingredient-dictionary/sensitizing

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