Article by: Kelly Dobos
I have quite a library of cosmetic science books in my home, some make their way to my office desk because they are the ones I use the most. Preservatives for Cosmetics by David C. Steinberg is one of those books, kept within arm’s reach and consulted at the start of every formulation project. So, I was pretty excited to take a look at updated and expanded third edition that recently published.
Cosmetics must not be contaminated with pathogenic organisms and must remain in this condition throughout the life of the product, including during consumer use. Complex global regulations, compatibility with cosmetic ingredients & packaging, and stability all make preserving a cosmetic product a serious and important task.
Cosmetic Preservative Chapters
Steinberg begins the book by laying out the changes in the regulatory and social climates that occurred in the seven years since the publication of the second edition. He follows this with general information about preservative approvals and regulations.
One of the most enlightening sections of the introduction is the description of the “ideal” preservative. Steinberg lays out twelve important criteria and it later becomes clear all twelve are hard for a single preservative to meet. This reinforces the challenge in ensuring adequate preservation of cosmetics and the need for multiple preservatives.
This chapter delves into the details of individual preservatives and is sorted by category, somewhat of a structure-function basis. The information includes the organisms against which the preservative is most effective, regulatory, and safety information. My favorite part of this section is the wealth of valuable formulation information such as solubility, inactivators and incorporation methods.
Because microorganisms are implicated in a variety of skin conditions some preservatives also have use as active ingredients in cosmetics that are also OTC drugs (see previous post on the difference between a cosmetic and a cosmetic drug product) by definition of the US FDA. Steinberg explains the monograph system and some of the challenges it presents to the selection of active ingredients. The remainder of the chapter provides details on the monographs that currently contain cosmetic preservatives as actives.
Chapter four takes a look at non-traditional preservatives and natural preservatives. Steinberg again reminds the reader of the characteristics of an ideal preservative and demonstrates some of the difficulty in relying solely on these approaches including poor aesthetics, stability concerns, and cost.
Water activity (aw), Hazard Analysis Critical Control Point (HACCP, pronounced ha-sip), and Current Good Manufacturing process (cGMPs) are discussed in chapter five. I feel like the section on water activity (binding water so that it is not available water to microorganisms) may have fit better in chapter four where they types of ingredients used was discussed. Overviews of HACCP and cGMPs are provided and give the formulator a good foundation for understanding how closely conditions in manufacture should be observed to prevent product contamination in manufacturing. I also think the section on cGMPs is a great resource if you are ever asked to audit a contract manufacturer.
This chapter discusses the use of chelating agents and antioxidants in conjunction with preservatives to enhance preservative efficacy and formulation stability.
What I think will be one of the most useful updates to the second edition is the expansion of a few tables of regulatory information into this full blown chapter. The regulatory environment is quite complex and when faced with the pressure to develop a “globally” acceptable formulation, this section will be invaluable to designing a preservative package for cosmetics. Regulations are laid out by country or trading block. Use limits and restrictions on conditions of use are organized in neat, easy to read tables. A list of global preservative suppliers is also included.
The third edition of Preservatives for Cosmetics is the perfect preservative reference book for cosmetic formulators. Steinberg’s writing is to the point and is filled with colorful anecdotes from his experience in the industry. The addition of a chapter on global regulations is an invaluable asset for developing formulations for multiple markets. I’m retiring my second edition to make way for this new book at my desk.