Methylchloroisothiazolinone

This compound (known as MCI for short) is a common preservative found in most 'rinse-off' products (IE: short skin exposure). However, it can apparently also be found in many cosmetics (foundation, sunscreen etc). It's called Kathon in industry, where it's used as a preservative in cutting fluids(!).

Okay, so most of this was stolen from the web - but it does seem to be remarkably similar (chemically) to anilinethiazolinones(ATZ). These are formed by the Edmann degradation reaction to sequence proteins. Which would mean that a methylchloro-TZ is just the MeCl derivative of one of these compounds (a hetrocyclic pentameric ring).

Presumably, 'preservative' means antimicrobial/antifungal agent. So it's basically an antibiotic.

If you have a hair care product that contains this you might want to stop using it *right now*.

I recently attended a conference of neuroscience researchers at the University of Pittsburgh, one of whom has found that this compound (as well as its relative methylisothiazolinone, or MIT,) is a mammalian neurotoxin. When these results are properly published I will post the reference, and perhaps even some excerpts if I feel like violating copyright law.

There are many hair care products that do not use either of these compounds, though you may find that so-called "natural" or "botanical" products are not often MIT/MCI free.

(Of course, if you really believe that putting plant extracts in one's hair helps it get clean, then you might as well keep using your spontaneous-orgasm-in-a-bottle-with-papaya folicle treatment; I don't think the neurotoxicity will bother you much . . .)