Is methylchloroisothiazolinone dangerous?

Shampoo preservatives

Methylchloroisothiazolinone is one of the preservatives commonly used in shampoos. In fact, it has many disadvantages, so why is it used in shampoos?

If you look at all the ingredients you'll get a clue, but the most common ingredient in shampoo is water.

Cosmetics, including shampoo, use purified water. It is not ordinary water, but water from which impurities have been removed as much as possible. This purified water does not contain any disinfecting ingredients like the chlorine in tap water. Therefore, if impurities are mixed in, it will immediately begin to spoil.

What's more, shampoo is used in humid bathrooms, which are ideal conditions for bacteria to grow.

That's why shampoos generally contain relatively strong preservatives .
In this article, we will explain in detail the safety of one such preservative, methylchloroisothiazolinone.

What is Methylchloroisothiazolinone?

Methylchloroisothiazolinone is a preservative active against bacteria, yeasts, and fungi, and is used in conjunction with a similar preservative called methylisothiazolinone .

It is a somewhat scary chemical that can cause chemical burns in high concentrations, but despite this, it has been used in cosmetics since the 1970s.

When it first started to be used, a concentration of 0.003% or less was recommended in Europe. However, many people developed allergies, so a concentration of 0.0015% or less was later recommended for wash-off cosmetics such as shampoos.

However, the situation worsened in the 2000s, as cosmetics containing methylchloroisothiazolinone at concentrations higher than the recommended concentration rapidly increased in Europe and the United States. As a result, the number of reports of allergies to cosmetics also increased .

Methylchloroisothiazolinone allergy symptoms

Methylchloroisothiazolinone poses a risk of skin allergies .

After contact, symptoms such as redness and itching may occur immediately, or percutaneous sensitization may occur.

Percutaneous sensitization is when the immune system reacts to a specific substance that comes into contact with the skin over a long period of time. In other words, the body prepares itself for an allergic reaction. After a sufficient period of contact, the body will develop an allergic reaction the next time it comes into contact with the substance.

If you are sensitized to methylchloroisothiazolinone...

I get allergic symptoms every time I come into contact with methylchloroisothiazolinone. There's no point in just changing shampoos because if this ingredient is in the shampoo, the symptoms will appear no matter what shampoo you use.

In this state, allergic symptoms may occur all over the body, not just on the scalp and face that came into contact with the shampoo, but also on the hands, feet, back, neck, and anywhere else on the body.

Once an allergic reaction occurs, the only way to prevent it is to avoid the allergen.

Safety evaluation of methylchloroisothiazolinone.

As mentioned above, the allergic risk of methylchloroisothiazolinone is clear.

So, naturally, in many countries today, it is only used in low concentrations in wash-off cosmetics such as shampoos. It is rarely found in skin care products such as lotions and milks as it once was. It is also not used in high concentrations.

Below are some examples of rules set by each country:

Europe

Since 2016, the EU has banned the use of methylchloroisothiazolinone in leave-on cosmetic products. Currently, it is permitted to be present at levels up to 0.0015% only in rinse-off cosmetic products such as shampoos and shower gels.

Canada

Methylchloroisothiazolinone alone is prohibited. It is permitted to be used in shampoos only in combination with methylisothiazolinone. Furthermore, the combined concentration of both ingredients must not exceed 0.0015%.

Japan

Like many other countries, in Japan, methylchloroisothiazolinone is used in combination with methylisothiazolinone. It is not permitted to be used in leave-in cosmetics. However, it can be used in shampoos and other products at up to 0.1%. The concentration allowed is higher than in the EU and Canada.

EWG

EWG, an American organization that evaluates the safety of cosmetic ingredients , prohibits the use of methylchloroisothiazolinone in EWG-certified cosmetics.

Is it carcinogenic?

Methylchloroisothiazolinone is not known to be carcinogenic and is not on the International Agency for Research on Cancer (IARC) list of known carcinogens.