A preservative is a natural or synthetic ingredient that is added to products such as foods, pharmaceuticals and personal care products to prevent spoilage, whether from microbial growth or undesirable chemical changes.
The use of preservatives is essential in most products to prevent product damage caused by microorganisms and to protect the product from inadvertent contamination by the consumer during use. An ingredient that protects the product from the growth of microorganisms is called an antimicrobial. A preservative may also be added to a product to protect it against damage and degradation caused by exposure to oxygen, and in this instance, these ingredients are also called antioxidants. Without preservatives, cosmetic products, just like food, can become contaminated, leading to product spoilage and possibly irritation or infections. Microbial contamination of products, especially those used around the eyes and on the skin, can cause significant problems. Preservatives help prevent such problems.
Antimicrobials prevent the growth of molds, yeasts, and bacteria. Antioxidants keep personal care products from becoming rancid or brown, or developing black spots. Rancid personal care products may not make you sick, but they might smell bad or be a different color or consistency. Antioxidants suppress the reaction that occurs when ingredients in the product combine with oxygen in the presence of light, heat, and some metals. Antioxidants also minimize the damage to some essential ingredients or materials that are especially susceptible to oxidative damage.
In most cases, preservative ingredients are used to protect the product and help it remain safe and perform as intended over the lifetime of the product. These products are regulated in the US by FDA under the cosmetic previsions of the law and manufacturers must determine that they are safe for consumer use. Perhaps the most widely used preservativs in cosmetic products are a group of ingredients generally referred to as "Parabens" When preservative ingredients are used to protect the user against possible infection from microorganisms or help keep the levels of microorganisms on the body at a level that prevents infections, they are subject to the additional requirements that the FDA applies for over-the-counter drugs (topical antimicrobial products are drugs). In this case, they can only use antimicrobial ingredients that have been approved by the FDA as both safe and effective.
Preservative ingredients can be used at relatively low levels to ensure that the product performs effectively over the time it takes the consumer to finish the product. Without preservatives, personal care products could become contaminated with microorganisms or degrade from the adverse effects of oxygen.