A cosmetic preservative is a substance added to a cosmetic to prevent microbial growth, as well as chemical or physical changes to the product.

Preservatives disable microorganisms in various ways:

1. Causing chemical disruption directly to the bacterial cells, leading to their death.
2. Breaking down their cell membranes or draining their internal fluids.
3. Removing oxygen from their environment.
4. Retarding their growth, such as by changing their internal or external pH.

We have all heard of the side effects of chemical preservatives, so it sounds reasonable to avoid them if possible, as our bodies obviously don’t need any more unnecessary chemicals. In response to such consumer demands, the industry has started to introduce the concept of preservative-free products. Let’s first have a look at some of these concepts.

How Preservatives Are Selected

Certain preservatives work only under certain conditions. They all have their own limitations against different microorganisms such as mold, yeast, fungi, and bacteria. Generally speaking, a formulation chemist has to consider these factors when choosing the right preservative:

1. The pH during the production process and in the end products
2. Temperature during manufacturing
3. All ingredients and components in the finished product
4. Intended shelf life of the product
5. Shipping and storage conditions
6. Temperature of the location where the products are going to be sold and used

If a company can guarantee the safety and quality of a product without using synthetic chemicals, there is a chance the cosmetic can be made preservative-free. Here are my observations of how this is currently being achieved in beauty products.

1. Natural Derivatives

Some natural extracts, such as wheat germ oil, sea salt, sugar, or alcohol, can extend the shelf life of a product, but only by a little—a few weeks or 10 percent of its original shelf life, at most. But these extracts are usually only effective on certain types of microorganisms, not all of them, and they often need to make up a large portion of the product to be effective.

For example, in a lotion base, we can use about 20 to 30 percent alcohol to achieve a 12 to 18 month shelf life. A similar percentage would work with salt and sugar in dry products, but the downside is that the products might then be irritating to the skin, or have an unappealing texture.

2. Natural Identical Preservatives

There are substances that naturally exist on earth that can be reproduced or synthesized. These substances have other functions besides preservation such as fragrance, moisturizing, alkalization, etc. So they have been classified for their other functions in the formula, instead of being labeled as preservatives. They just aren’t calling it a preservative. Glycerine, citric acid, sorbic acid, and potassium sorbate all fall into this category.

3. No Preservatives

This is achievable if the products are completely free from water, such as clay powder, dry bath salt, or oil and wax-based products. For oil, balm, or wax-based products, a preservative must often be used to retard rancidity. The safety of these products is questionable, as some may have serious issues with bacterial contamination, breakdown, etc. If the product is made fresh on site and used up immediately, which might be the case in a spa or beauty clinic, then it’s not a bad idea. Products completely free of preservatives are not designed for mass market sale or standard retail environments.

4. So-Called ‘No Preservatives’

There is some anecdotal evidence from bloggers, cosmetic insiders, formulation chemists, and others that some of the cosmetics labeled as preservative-free are actually not as they appear. Here are some observations from industry insiders:

a. Commercial Name: Ingredients are mentioned by their commercial name instead of their scientific name. These names can be misleading, such as Herbigerm, for example. Herbigerm contains parabens (widely used chemicals), but the name sounds much greener and healthier.

b. Ingredients Already Contain Preservatives: Preservatives have been pre-combined with other ingredients but not mentioned separately. Many cosmetic ingredients are supplied to the manufacturers in liquid form (such as most sulphactants), and these are already pre-mixed with a good amount of preservatives.

c. Using Their Own Names: Under the protection of patents or trade secrecy law in some countries, it is legal for a company to use its own names for ingredients, and these may contain undisclosed preservatives.

d. Less Than 1 Percent of Ingredients: In some countries, it is not compulsory to list ingredients that make up less than 1 percent of the product.

In the eyes of some formulation chemists, including myself, it is just not possible that certain types of products contain zero preservatives. Maybe it is possible that these companies are using safe preservatives but are not labeling them properly—maybe. But the bottom line is that the consumer should have the right to be well-informed and know exactly what’s in a product before buying it.