Why are they necessary?
Most cosmetic products contain water and nutrients for microorganisms to grow and flourish. It has been amply demonstrated that inadequately preserved cosmetics can be hazardous to human health. Cosmetics with contaminants are not only unappealing to the eye and smell bad but they may also be pathogenic resulting in the need for medical attention. Skin infections can result from contaminated body products, especially when applied to cracked dry skin.
Cosmetics are often stored in the bathroom where the environment is warm and moist. Our skin carries an abundance of microorganisms in addition to tap water which in turn is not sterile. Often times this water is introduced into products in either accidentally or even on purpose. The most carefully prepared products may become contaminated under these circumstances.
Preservative Free Products
One of the major reasons many of us make our own personal care products is that we want a safer and more nourishing product than those that we may be buying off the store shelf. We want to choose what we put on our skin, and what we leave off our skin.
You do not need to visualize colonies of bacteria and mold for the product to be contaminated. By the time you can see the contamination is has most likely been there for a while.
There are ways to produce a cosmetic product without preservatives. All methods start with an aseptically prepared product. (aseptic technique refers to a procedure that is performed under sterile conditions) If a product is manufactured under sterile conditions it need only be protected from consumer contamination. This may be achieved by using single dose containers, aerosolizing (a solid or liquid are suspended in gas or air) or packaging in very small orifice TUBES. As a home manufacturer it is unlikely that you will have this special packaging at your disposal. You can make up small amounts of product at a time and use it quickly while storing it in the refrigerator between uses.
Another good option is to use AIRLESS CONTAINERS. These containers keep air from contaminating the product and the closed system keeps dirty fingers out!’
As stated earlier a product requires water for microorganisms to survive and reproduce. Additionally it must be in a form that the microorganisms can use. The food industry has many traditional methods of self-preservation that may be applied to cosmetics.
HONEY: Even though honey has a high level of water the water is bound by a high level of sugar and microorganisms are unable to grow in it.
GLYCERIN: glycol will also bind to the water making it unavailable to microorganisms. High levels of glycol usage in a formula (15-20%) will also preserve a product. The old Rose Water and Glycerin Creams needed no preservative to keep them.
ALCOHOL :Formulas with an ethanol/alcohol content of 15% or more do not need more preservation as the alcohol will keep the product.
SUGAR: High levels of sugar in a product can protect a product from spoilage. Perfect examples of this are marmalade and sweet pickles.
HEAT: Heating, cooking and pasteurizing are all natural forms of preservation. This may be particularly useful for single use products.
DESSICATION: Removing all the water from a product will protect it from spoiling. For this reason I always recommend using dried herbs over fresh in cosmetics. Once water is reintroduced to the product the product is then once again open to spoilage.
ANHYDROUS: Products that do not contain any water such as balms and ointments are self preserving and need only an antioxidant.
SALT: Extremely high levels of salt in a product will act as a preservative . Ancient Mariners preserved their meat in this way and the Egyptians used salt to help preserve their mummies by soaking them in a brine solution.
COLD: Placing a product in cold refrigeration will stop any microbial growth if the product if sterile.
ACID pH:The natural preservative activity can be amplified by using as low a pH as possible in your products. This may be done by adding citric acid, vinegar, LACTIC ACID, SODIUM PCA or other alpha hydroxyl acid agents.
ALKALINE pH:A highly alkaline pH may also preserve a product. Unfortunately a product with high alkalinity will dry and irritate the skin and strip the natural oils.
Just as some ingredients will help preserve your product other ingredients may also inactivate your preservative. For example nonionic surfactants and ethoxylated materials may interfere with the activity of parabens. Relatively minor changes in the pH of a product may radically change the activity of organic acids such as SORBIC ACID (POTASSIUM SORBATE).
Among the most effective natural preservatives are essential oils and various herbs such as rosemary, clove, thyme, cinnamon, tea tree and lavender. In most cases they are more organism specific than their synthetic counterparts. This means they may be effective against one organism but not another. They must be carefully blended to create a synergistic effect against a range of organisms.
Chemical plant constituents vary greatly in composition. The chemicals present in all parts of a plant naturally protect it from its environment. It is when a plant has been tampered with (such as hybrids) that it will start to lose its natural immunity and become prone to mold, mildew and other disease. Many plant extracts are not only capable of resisting disease but in some cases will actively destroy them. The biggest drawback to using essential oils, are their strong odors when used at the levels needed to be effective. Many essential oils such as cinnamon and clove are also too strong and may cause skin irritation and stinging.
What to look for when choosing a Preservative
Ideally when looking for a suitable preservative for cosmetics there are many things to be considered and to look for:
1. What ingredients are you using? Are they oil soluble or water-soluble?
2. What will the final pH of your product be?
3. What sort of packaging are you using?
4. Broad Spectrum Activity. It should be active against both gram positive and gram negative bacteria.
5. Long lasting: it should continue to work under normal conditions and even less favorable conditions.
6. Rapid action: if your cosmetic should become contaminated the preservative should act quickly to re-sterilize it.
7. Non-sensitizing: It should not have any allergic or sensitizing tendencies.
8. Non-toxic and Non-irritating
9. It should be compatible with all the ingredients in the formula
10. Stability: It should be chemically stable to heat or not undergo disintegration during storage.
Synergy and Preservatives
Synergy refers to the phenomenon in which two or more discrete influences or agents acting together create an effect greater than that predicted by knowing only the separate effects of the individual agents. Over the years chemists and microbiologists have found that by combining various chemical preservatives together a synergy can be created that will lessen the amount of preservative needed to adequately protect a product. Many of these chemical combination’s may be used at rates as low as 0.2% or 2 grams per 1000 when combined versus a rate of 2% or 20 grams per 1000 on their own. By using these synergistic combination’s the likelihood of skin reactions and toxic side effects of chemical preservatives are far less likely to occur. While still not an ideal situation the options offered to the consumer have improved greatly over time.
Parabens were first introduced in the 1930’s and are still the most widely used preservatives in cosmetics. Parabens are found worldwide in body care products, foods, glues, fats and oils. They are widely accepted as inexpensive, colorless, odorless and non toxic. In 1995 the US Environmental Protection Agency granted GRAS (Generally Recognized as Safe) status to parabens. In the US the total paraben exposure per person is estimated to be about 76 mg per day. Cosmetics and Personal care products account for 66% of the total exposure to parabens.However, as a result of more recent evidence suggesting a link between parabens and breast cancer and parabens and testosterone levels the CIR (Cosmetic Ingredient Review Expert Panel) have elected to reevaluate their safety. At one time the parabens absorbed by the body were thought to be fully metabolized by esterases in the liver, kidney and excreted in the urine. They were not thought to accumulate in the body. A study conducted in 1998 found that Parabens bind to rodent uterine estrogen receptors and human estrogen receptors. Because estrogen is a major etiologic factor in the development of human breast tissue it was thought that underarm cosmetics may contribute to breast cancer as parabens were found in excised tumors. Methylparaben was found at the highest level. Another study found a antispermogenic potential in parabens that could adversely affect the secretion of testosterone in the male reproductive system.
As far as parabens and allergic reactions they are considered to be weak sensitizers. There have been numerous reports of allergic reactions but for the most part they involve repeated use on damaged skin and wounds.
Cosmetic microbiologists continue to face challenges to develop preservative formulations that are less aggressive to consumers but will also protect against product contamination. Microbial contamination of cosmetic products is a matter of great importance to the industry and poor outcomes can result in both product and great economic loss. Regulations regarding microbiological content in cosmetic products do not exist. The only requirement is that they “must not cause damage to human health when applied under normal or reasonably foreseeable conditions of use.
The seventh amendment to the Cosmetic Directive effective March 2005 incorporates a new concept based on microbiological criteria PAO (period after opening). The PAO is an indication of how long the cosmetic product can be used after it is first opened without any deterioration linked to microbes. The PAO is indicated by an open jar symbol accompanied by the number of months within which the product should be used. For example 12M would mean 12 months or menses. This should not be confused with an expiration date. Though I have looked for this symbol on packaging I have yet to find it.
Cosmetic raw materials, including preservatives, are not subject to registration before marketing in the United States; however most cosmetic manufacturers would not use a raw material that has not underdone extensive safety testing and this is particularly true for preservatives.
What is the different between and “anti-oxidant” and a “preservative”?
Preservatives will stop bacterial and fungal growth. Examples of preservatives are Phenoxyethanol,
Anti-oxidants are used to keep oils from going rancid or to help prevent “free radical” damage to the skin from environmental factors such as UVA and UVB rays. Some examples of anti oxidants are Vitamin E, Vitamin C and Rosemary Oleoresin.
When do I need a preservative and when do I need an anti-oxidant?
Bacteria and fungus need water to grow. Any product that has water content should also have a preservative. Even if your water is sterile you still need a preservative. Some examples are:
Lotions, Creams, Liquid Shampoos, Bubble Baths, Shower Gels, Gel Bases, Floral Waters and Facial Toners.
Most all oils will become rancid over time. Due to oxidation they break down and develop a rancid odor. Essential Oils will also lose their strength and perfume when exposed to air or heat. Most any products that contain a large amount of oil will need an anti-oxidant: Some examples are:
Lotion Bars, Ointments, Super-fatted Soaps, Bath Salts with essential oils, Massage Oils, Bath Oils, and Salt Scrubs.
Choosing the right preservative for a product that is meant to be marketed is a long a tricky ordeal. There are several options to be considered and products need to be tested for safety. If you are interested in marketing your own line of products this information provided is only a starting point for you. Even small cottage industries have a responsibility to their customers to assure that proper testing has been done and that their product is safe for sale. This almost always means using a synthetic chemical preservative unless you have come up with and tested your own synergistic blend of herbs and oils. This is not impossible but it is a lot of work and the testing will be expensive.
A huge advantage to making your own body and hair care products it that you can choose not to use preservatives at all. Care should be taken to refrigerate non preserved products and use them up quickly. Additionally when formulating your own products you may use ingredients such as honey, glycerin, alcohol, and essential oils that will not only add nutritional value to the product but help extend the shelf life of your product. Handmade cosmetics have been around for centuries and the thought of having to use a preservative (or not) should not deter us from this most enjoyable and rewarding pastime.
You and only you are responsible for your own testing as we cannot control the environment in which other products are made. The stability & nature of your products may be altered depending on storage conditions, or when used in combination with other ingredients. This is beyond our control and we strongly recommend lab tests prior to commercial runs. DIY Cosmetics cannot accept any liability in this regard.