Monday, November 7, 2011

More About Preservatives

I spoke briefly about preservatives on an earlier post but wanted to revisit the subject due to it’s importance. When I started making bath and body products about 8 years ago, I did endless research on all aspects of the process. The thing I found most bewildering was the preservative issue. There was so much controversial and contradictory information I didn’t know what to believe. My biggest fear was contamination of my products, so, my priority was to make sure I used the best and safest preservative available.

The microbes that can infect formulas primarily include bacteria, mold and yeast. In small quantities, they do not pose much of a problem, but when they multiply, can have catastrophic consequences. Bacteria like Pseudomonas can cause all kinds of health problems including skin and eye infections, toxic shock and strep throat, to name a few. Yeast like Candida albicans can cause thrush, and many other bacteria can cause products to have a foul odor, change color or otherwise break down.

When first starting out, I frequently went to craft shows where handmade products were readily available. I wanted to see what everyone was doing and how they were doing it. I and was astounded at the number of times I was told a product was 100% natural. When I asked specifically about the type of preservative, I received a variety of answers, however, most often was told Grapefruit Seed Extract, Vitamin E and Rosemary Oil Extract.

Let’s explore those particular ingredients.

Grapefruit Seed Extract

Here is a “word for word notation” taken from an online site pertaining to Natural Cosmetics.

“Grapefruit Seed Extract - A natural antibiotic, antiseptic, disinfectant and preservative. It is used to promote the healing of almost any atypical skin condition. According to published sources it is effective against more than 800 bacterial and viral organisms, 100 strains of fungus, and a large number of single-cell and multi-celled parasites. This preservative is used by many handcrafters in products that contain water.”

In doing further, extensive research just on Grapefruit Seed Extract, it would appear that the antimicrobial effects of this product are directly related to residual chemicals which are used to manufacture the extract in the first place, not the extract in and of itself. Thus, in reality, Grapefruit Seed Extract is not a “natural” product, nor, on it’s own does it have the antimicrobial properties as claimed by some.

Vitamin E

Vitamin E is an antioxidant. An anti-oxidant is a preservative that reduces the rate of oxidation in oils that oxidize quickly. Oxidation is a chemical process that occurs when oils or other natural ingredients are exposed to oxygen. Anti-oxidants extend the shelf life of your products by reducing the rate of oxidation of your oils. It does NOT have antimicrobial benefits, thus, using it as a preservative is misleading. It will help prevent oil content from becoming rancid as quickly, however, will not prevent bacteria from growing in products which contain water.

Rosemary Oil Extract

This is also an antioxidant and is very beneficial in extending the shelf life of oils, however, does NOT inhibit the growth of bacteria in products containing water.

Now, lets look at the most commonly used synthetic preservatives. As you will see, each and every one of these has received negative press in one way or another.


Paraben preservatives are listed under multiple names and are used to preserve the majority of cosmetics on the market today. Paraben preservatives have recently come into question with new studies that link the daily exposure of paraben preservatives to breast cancer and endocrine-disruption issues. It must be noted that the European Cosmetic Toiletry and Perfumery Associan affirm that parabens are hydrolyzed in the skin and that they do not enter the bloodstream. Parabens are not officially identified or listed as an endocrine disrupting chemical by any government or regulatory organization.

Parabens are synthetic preservatives that have been for almost a century as “broad-band” preservatives (anti-bacterial and anti-fungal) which means that they work within a formula to prevent the growth of multiple possible contaminants such as bacteria, yeast, mold and fungi. They can be found in approximately 80% of cosmetics such as make-up, lotion, deodorants and shampoos.

Much research still needs to be done to ultimately determine the true long term safety and consequences of the wide spread use of paraben preservatives as a daily part of our skin regimen. In the interim, many people have jumped on the bandwagon of initial studies and have declared parabens as the demon of all demons as pertaining to safety. More than any other ingredient, preservatives are considered by consumers to be the worst ingredients cosmetic chemists can use in formulas.

Formaldehyde Donors

Formaldehyde derivatives are the next most common preservative. These compounds interfere with membrane proteins, which kills microbes. They are effective against bacteria, fungi and mold. Bad press and real safety concerns have led cosmetic chemists to stop using formaldehyde. Instead, ingredients that dissociate into formaldehyde when put in a water solution are used. These are compounds like DMDM hydantoin, imidazolidinyl urea and gluteraldehyde.

Phenol Derivatives

Phenol derivatives have been used in cosmetics for many years and can be effective against a range of microbes. Unfortunately, they are not as effective as the parabens and formaldehyde donors. The most common example is phenoxyethanol.


This is a category of compounds which contain nitrogen and have a positive charge when placed in a solution. Studies have shown that many of them demonstrate an ability to kill microbes. This includes ingredients like benzalkonium chlroide, methene ammonium chloride and benzethonium chloride. Due to their cationic nature, they are less compatible with anionic surfactants, which limits their application and use.


Ethanol has been proven to be a great preservative. The downside is that it must be used at high levels, therefore, faces considerable environmental restriction. Other compounds like benzyl alcohol, dichlorobenzyl alcohol and even propylene glycol have also been shown to exhibit antimicrobial effect. At lower levels, these compounds are less effective at preserving products.


These are some of those long words you see on commercial product ingredients lists which you wouldn’t even begin to try to say. Methylchloroisothiazolinone and methylisothiazolinone are reported to be effective at incredibly low levels and at a wide range of pH levels and in many different formulas. Their use has been thwarted, however, by at least one study that suggested it could cause skin sensitization.

Organic Acids and Others

Various other compounds are used as preservatives but all face limitations of one kind or the other. Some of the most important include: sodium benzoate, chloracetamide, triclosan and iodopropynyl butylcarbamate. Pyridine derivatives like sodium pyrithione and zinc pyrithione are frequently used in anti-dandruff shampoos.

The Moral of the Story

This is what I hope you take from my ramblings. Preservatives are designed to kill cells. That is why they are effective. Unfortunately, that is also why they are potentially hazardous. They do not easily discriminate between good human cells and bad microbial cells but ultimately, the risk from using preservatives is significantly lower than that of using unpreserved cosmetics. There are safe levels of “toxic” chemicals. All chemicals can be deadly if one is exposed to high enough levels. Remember, it’s the dose that matters! The most important word to keep in mind when considering preservatives, is "balance". You need to include enough preservative to control microbial growth, yet not too much so as to cause allergies, dermatitis or other side effects.



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