Dear Valerie: Are there ingredient levels that count as “technically unavoidable impurities” versus levels that trigger regulatory oversight? For example, 1-4 dioxane. — Addie Tive

Dear Addie,

In my opinion, most regulations surrounding impurities are technically unavoidable. For example, cyclic silicones are strongly regulated for use in the EU for a variety of reasons. While not permitted when intentionally added, cyclic silicones are permitted up to 0.1% in final formulation as technically unavoidable impurities. The law (as written) explicitly states this in detail.

However, in California, the regulations are more ambiguous. Assembly Bill 496 restricts the use of intentionally added cyclotetrasiloxane (D4) starting in 2027. However, the language is not clear because you can intentionally add an ingredient that is not D4 but contains trace impurities of D4. There is no clarity on whether this technically unavoidable impurity is intentionally added to the formula. In this case, it’s a matter of risk appetite.

In the case of 1,4-dioxane, there is no consideration whether it’s technically unavoidable or intentionally added. The final product has a ppm limitation, and you must not exceed the limitation in the geography which has prescribed the ppm limit.

While the D4 challenge is easy to maneuver around (just don’t add anything intentionally or with technically avoidable impurities), the challenge with qualitative regulations like 1,4-dioxane is that regulations don’t go into detail about the best suitable testing methodologies for analysis. Lawmakers simply think an ingredient is bad and ban it. Much of the volunteer work I do with the Technical and Regulatory Committee for the Independent Beauty Association is educating lawmakers on the nuances of cosmetic ingredients and formulations.

There is on additional challenge I’d like to mention on 1,4-dioxane since you specifically mention it. When 1,4-dioxane regulations were being imposed, I was quite diligent to test for 1,4-dioxane on freshly produced product, product that underwent accelerated stability with elevated temperatures, and real time stability interval testing. I discovered that the testing laboratory’s methodology really matters, as well as ensuring I tested at all the time points I indicated. I learned early on 1,4-dioxane levels can rise over time, particularly in surfactant systems and with heat exposure, and not all testing methodologies are suitable for accurate 1,4-dioxane detection.

All this being said, you have to read each regulation thoroughly to understand what is implicitly stated in the law. All the proposed bill texts are available online. You can also join industry groups to see what regulations could impact your brand the most.

Looking for more answers? In our December issue, Dear Val also answered questions about foundation color change and ceramides. You can find all of Valerie George’s insights here.

Valerie George

askvalerie@icloud.com

Valerie George is a cosmetic chemist, science communicator, educator, leader, and avid proponent of transparency in the beauty industry. She works on the latest research in hair color and hair care at her company, Simply Formulas, and is the co-host of The Beauty Brains podcast. You can find her on Instagram at @cosmetic_chemist or showcasing her favorite ingredients to small brands and home formulators at simply-ingredients.com