Methylisothiazolinone and Methylchloroisothiazolinone (MI and MCI, respectively) are organic compounds that are effective preservatives in a variety of cosmetic products like shampoos, conditioners, and eye makeup removers. These compounds offer antimicrobial benefits, preventing the growth and reproduction of bacteria, mold, and fungi. Derived synthetically, MI and MCI protect the efficacy, color, and consistency of products. Most personal care products contain preservatives for these very reasons.

Use of MI and MCI in Cosmetic Products
Concentrations of MI and MCI used in product formulations are extremely small. Extensive testing and research have determined that MI and MCI can be used safely in rinse-off products at concentrations below 15 ppm (parts per million) and in leave-on products at concentrations below 7.5 ppm. This means that if there were a million parts (grams) in the formula, MI and MCI would only take up 15 or 7.5.

The only Nu Skin® products that contain MI and MCI are rinse-off products at concentrations of about 5 ppm, well below the15 ppm margin of safety. These products include shampoos, conditioners, and body washes.

Research on the Safety of MI and MCI
Overwhelmingly, studies on the use of MI and MCI in personal care products attest to their safety. In 1992, the Cosmetic Ingredient Review (CIR), an independent panel of physicians and scientists that assesses cosmetic ingredients, thoroughly reviewed the research on MI and MCI and found them to be safe for use in personal care products at the recommended levels. Furthermore, the Food and Drug Administration (FDA), which regulates the ingredient safety in cosmetic products, backs the use of MI and MCI when incorporated at concentrations determined safe and effective.

At a recent meeting of the American Society for Cell Biology, one abstract claimed that MI could affect the nervous system. Any concerns created by this isolated abstract are unwarranted because the context of this research does not relate to the cosmetic use of MI. The study exposed rat nerve cells in test tubes to very high doses of MI. This kind of exposure is not comparable to the minute levels of MI in a skin care product. In response to this study, the Cosmetic Toiletries and Fragrance Association (CTFA) reviewed the use of MI, reiterating the problem of comparing this research to the actual use of MI in cosmetic products:

The experiments conducted with MI on extracted nerve cells in laboratory containers do NOT remotely resemble the possible consumer exposure to this preservative. In fact, safety testing with animals has demonstrated that application of MI does NOT result in systemic toxicity to the preservative. Clinical and functional effects on the nervous system have NOT been observed in relevant safety tests. (December 6, 2004)

In short, the use of MI and MCI in personal care products is not a safety concern for consumers. MI and MCI, in recommended concentrations, provide vital benefits to products, preserving their quality, effectiveness, and safety.

Nu Skin's Commitment
Nu Skin is committed to providing its customers with the best and safest products. Having reviewed the latest research performed by the cosmetic industry, the FDA, and other qualified sources, we can assure our customers that methylisothiazolinone and methylchloroisothiazolinone are safe and effective as preservatives in Nu Skin products.