1, Prevent growth of microorganism by creating an environment that is hostile to them; 2, Block the oxidation process; 3, Inhibit the enzymatic process especially in fruits and food.
Thriving in a Tough Environment
Personal care products contain water and nutrients where microorganisms grow and flourish. Cosmetics with contaminants are not only unappealing to the eyes and smell bad, but they can also produce skin infection, especially when applied to dry and cracked skin. Products can be manufactured preservative-free by using an aseptic technique. In this technique, products are prepared under sterile conditions. The products only need to be protected from consumer contamination that can be achieved by using a single dose container, aerosolizing (solid and/or liquid product are suspended with a propellant) or packaging the product in very small orifice tubes.
Before creating the preservative system, formulators must consider three questions: What ingredients are being used; i.e., are they oil-soluble or water-soluble? What will be the final pH of the product? What type of packaging is being used?
An ideal preservative system should have eight attributes: Broad-spectrum activity, long-lasting, rapid action, non-sensitizing, non-toxic and non-irritating, compatibility, chemical stability and synergy with other preservatives. Combinations of preservatives and antioxidants are advantageous to products. Preservatives will stop bacterial and fungal growth while antioxidants keep the oils in the product from going rancid and prevent “free radical” damage.
There are several options to consider when choosing the right preservative for a product, including low levels of methyl paraben and ethyl paraben, as well as natural preservatives such as (suprapein and biopein). Products must be tested for safety.
Manufacturers have a responsibility to their consumers to assure that the proper testing has been done and the product is safe and effective. Unpreserved products lose all the valuable benefit and become dangerous to consumers, especially fruits, foods and under the eye and skin care products. Product texture depends on its composition, humidity and climate factors. Personal care products stored in the bathroom need preservatives because the bathroom is a moist and warm environment which are the perfect conditions for bacteria and mold to flourish.
The FDA has classified parabens as “GRAS” ingredients, which means they are safe for use in products according to medical and toxicological experts. Some scientific studies have suggested that butylparaben and propylparaben can mimic the effect of the endocrine hormone, estrogen, when tested at high concentrations in cell cultures and female mice. This effect is sometimes referred to as endocrine disruption. (Mirik Dik Davis and T. Thomas D.B (2002) J. Nat R Cancer Institute 94(20)1578-80).
Preservatives can have side effects:
- Biphenyl can cause skin discoloration, headaches and intestinal problems.
- Sodium, potassium and calcium salts of benzoic acid can cause hyperactivity in children, allergic reactions.
- Sodium and potassium nitrates and nitrites can cause intestinal discomfort, headaches and skin problems. They can also produce nitrosamine, a human carcinogen.
- Butylated hydroxytoluene (BHT) is used in food for its antioxidant properties. Although California has listed butylated hydroxyanisole (BHA) as a carcinogen, a low intake of BHA shows no significant association with an increased risk of cancer.
- Sodium and potassium bromate can influence the development of cancer.
- Mono sodium glutamate can cause headaches and nausea.
- Sodium sulfite, sulfur dioxide and sodium bisulfite can cause allergic reactions.
- Propyl gallate, an antioxidant, is a food additive that has been linked to cancer in some studies.
- Tertiary butyl hydroquinone (TBHQ) can cause nausea and violent mental agitation.
About the Author
Mohinder Singh, PhD, is a consultant to Blistex Inc., Oakbrook, IL. He can be reached at MSingh@blistex.com.