Polyethylene glycol (PEG) is a broad class of synthetic polymers used across multiple industries, including medicine and personal care. PEGs are widely utilized due to their stability and ability to dissolve in water. The number “75” in PEG-75 is a designator that relates to the specific properties or structure of this ingredient, signifying a distinct grade or molecular weight within the large family of PEG substances.
Defining PEG-75: Chemical Structure and Source
Polyethylene glycol is a polyether compound derived from petroleum through the polymerization of ethylene oxide. Its base structure consists of repeating ethylene oxide units. The number 75 relates to the average molecular weight or the number of ethoxylation units added during synthesis. In cosmetics, PEG-75 is often used in derivative forms, such as PEG-75 Lanolin, which is lanolin ethoxylated with approximately 75 moles of ethylene oxide.
A higher number, like 75, indicates a greater chain length and a higher average molecular weight compared to PEGs with smaller numbers (e.g., PEG-4). This higher molecular weight typically results in a waxy solid or semi-solid gel at room temperature, distinguishing it from lower molecular weight PEGs that are liquid. PEG-75 and its derivatives are highly water-soluble, making them valuable for formulating water-based cosmetic products.
The Role of PEG-75 in Cosmetic and Health Products
PEG-75 performs multiple roles in cosmetic formulations. As a humectant, its structure attracts and retains moisture, which helps to hydrate the skin and prevent water loss in the product itself. This water-binding capability makes it a popular component in creams, lotions, and other moisturizing products.
PEG-75 also acts as an effective solvent or vehicle, helping to dissolve other ingredients, such as fragrance oils, plant extracts, or active compounds, ensuring they are evenly dispersed throughout the formula. This is useful for achieving a uniform product consistency. Furthermore, in derivative forms like PEG-75 Lanolin, it functions as an emulsifier, which is necessary to stabilize formulations containing both oil and water components.
Emulsifiers reduce the surface tension between two immiscible phases, creating a stable, homogenous blend. Due to its higher molecular weight and solid nature, PEG-75 also serves as a binder to hold powdered products together and can be used as a consistency enhancer to modify the thickness or viscosity of creams and gels.
Understanding the Safety and Regulatory Status
The primary concern raised about PEGs stems from the manufacturing process known as ethoxylation, which involves the use of ethylene oxide. This process can lead to the formation of trace amounts of a byproduct called 1,4-Dioxane. 1,4-Dioxane is classified as a likely human carcinogen by the U.S. Environmental Protection Agency, although it is not intentionally added to cosmetics.
The Cosmetic Ingredient Review (CIR) Expert Panel, an independent scientific body, has evaluated PEG-75 and its lanolin derivatives multiple times. The Panel has concluded that PEG-75 and its related ingredients are safe for use in cosmetics under current practices and concentrations. Safety is maintained because manufacturers can remove the 1,4-Dioxane contaminant using purification techniques like vacuum stripping.
Regulatory bodies such as the U.S. Food and Drug Administration (FDA) periodically monitor the levels of 1,4-Dioxane in cosmetic products. The European Scientific Committee on Consumer Safety (SCCS) has also concluded that trace levels of 1,4-Dioxane at or below 10 parts per million (ppm) in cosmetic products are considered safe. Regulatory oversight and industry purification practices generally ensure the final product is safe for consumer use.