Is Kathon CG safe?

The Cosmetic Ingredients Review Expert Panel have this year been reviewing the safety of the MCI / MI blend, and have just published their Draft Final Amended Report for Panel Review. It’s a beast of a document — it carries past historical information and detailed minutes of past meetings — and you can read it all here on PDF.  

In 1992, their opinion was that the MCI / MI blend (ie Kathon CG) may be safely used in rinse-off products at a concentration not to exceed 15ppm (parts per million; 0.0015%) and in leave-on products at a concentration not to exceed 7.5 ppm — and these are the limits set today in the US.

I’d hoped that they may conclude Kathon CG may be unsafe at any concentration in leave-on, as has been decided upon by experts in the European Union, but regrettably it appears they are not moving that way.

Although not yet finally approved, their current suggested position is outlined in their conclusion, which reads:

MCI/MI is safe in cosmetics when formulated to be non-sensitizing, based on the results of a quantitative risk assessment (QRA) or similar methodology; however at no point should concentrations exceed 7.5ppm in leave-on products or 15ppm in rinse-off products. The Panel also concluded that the data are insufficient to support the safety of MCI/MI in products which may be incidentally inhaled.

The only change being proposed appears to be the addition of that last line, which I take to be in reference to anti-perspirants and hair sprays, for example.

However the document does also include new input from The Personal Care Products Council, who were invited to submit views — you can see them as several memorandums, right at the end — which the Panel may yet take into account before publishing their Final Amended Report.

Among them is this line from the PCPC:

Except for incidental concentrations (carry-over from use of an ingredient preserved with MCI/MI), MCI/MI should not be used in leave-on dermal products

And this one:

Caution should be exercised to limit the number of products where MCI/MI is present in leave-on skin applications … and should always be supported by a favourable QRA [Quantitative Risk Assessment]

And, the big one, with my emphasis:

We suggest that the conclusion of the CIR report be revised to the following:
“The Panel concluded that the ingredient mixture MCI/MI is safe in leave-on hair care products and rinse-off cosmetics when formulated to be non-sensitising based on the results of a QRA … however, at no point should concentrations exceed 7.5ppm in leave-on hair products or 15ppm in rinse-off products ….”

So, in other words, the PCPC view appears to be that MCI/MI should not be used to preserve leave-on dermal cosmetics, and may only be acceptable in trace amounts from a ‘carry-over’ ingredient use, but that it would be OK in, for example, hair conditioners / masks. 

Let’s hope that the CIR take this recommendation on board, and that it takes a stricter line than it is currently proposing. We should know more next month (December 2019). I’ll update.

A final point, but an important one: reading the minutes of the Full Panel Meeting (September 17th, 2019), page 33 of the PDF, it appears the Panel have agreed to reopen the safety report for methylisothiazolinone as a standalone preservative. 

This is good news. The US could be edging closer to effectively banning or at least more heavily restricting isothiazolinones in leave-on skincare. 

1 Comment

  1. Ananth V.P

    When it is not environmental friendy and toxic to aquatic species why not completely banned.


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