Polyethylene glycols (PEGs) are common ingredients in personal care and cosmetic products. When consumers see chemical names like “PEG 150” on a product label, questions about safety naturally arise. This article clarifies the safety profile of PEG 150 by examining its chemical identity, primary contamination concern, and conclusions from scientific review bodies.
Defining Polyethylene Glycol 150
PEG 150 is a specific polymer within the polyethylene glycol family, a synthetic compound derived from the reaction of ethylene oxide and water. In cosmetic formulations, PEG 150 is typically found as a fatty acid ester, such as PEG-150 Stearate or PEG-150 Distearate. These ingredients are white to off-white waxy flakes or solids that are highly water-soluble.
The number “150” signifies the average number of ethylene oxide units (monomers) that make up the polyethylene glycol chain, corresponding to a high molecular weight. This high molecular weight dictates the ingredient’s physical properties and how it interacts with the skin. PEG 150 functions primarily as a viscosity modifier, meaning it is used to thicken and stabilize products like shampoos, conditioners, and body washes. It also acts as an emulsifier, helping to blend oil and water-based ingredients for a smooth, uniform consistency in creams and lotions.
Understanding the 1,4-Dioxane Contamination Concern
The concern over PEG ingredients, including PEG 150, does not stem from the polymer itself, which is generally considered non-toxic and inert. The primary issue is the potential presence of a trace contaminant called 1,4-Dioxane, which is a byproduct formed during the manufacturing process of ethoxylation. Ethoxylation is the chemical reaction used to create many PEG compounds, where ethylene oxide is added to an alcohol or fatty acid.
1,4-Dioxane is a known animal carcinogen and is classified by the U.S. Environmental Protection Agency (EPA) as likely to be carcinogenic to humans, and by the International Agency for Research on Cancer (IARC) as possibly carcinogenic. It is not intentionally added to products but forms as a trace impurity, identifiable by ingredient names containing “PEG,” “-eth-,” or “-oxynol-.” This compound is highly mobile and persistent, making its presence a significant concern in both consumer products and the environment.
Manufacturers have a responsibility to remove this contaminant because 1,4-Dioxane can be absorbed through the skin, although it also readily evaporates from products that remain on the skin for hours. Purification is achieved through a process known as vacuum stripping, which effectively minimizes the amount of 1,4-Dioxane that remains in the final ingredient. This purification step is necessary to ensure the safety of the final cosmetic product.
Expert Review and Regulatory Status
The safety of PEGs, including PEG 150, has been thoroughly evaluated by independent scientific bodies. The Cosmetic Ingredient Review (CIR) Expert Panel concluded that PEGs are safe for use in cosmetic products under current practices. This conclusion is based on the understanding that proper purification procedures are implemented during manufacturing to remove the byproducts.
The U.S. Food and Drug Administration (FDA) has consistently monitored the levels of 1,4-Dioxane in cosmetic products since the late 1970s, observing a significant decline in its presence over time. While the FDA does not set a mandatory federal limit for 1,4-Dioxane in cosmetics, it has historically recommended that manufacturers limit concentrations to no more than 10 parts per million (ppm). The European Commission Scientific Committee on Consumer Safety (SCCS) reached a similar conclusion, finding that trace levels of 1,4-dioxane at or below 10 ppm are considered safe for consumers.
Some regulatory bodies have established stricter limits to manage this contaminant. For instance, New York State has enacted legislation requiring 1,4-Dioxane concentrations in cosmetics to be at or below 10 ppm. The scientific consensus supports the safety of PEG 150 when used in consumer products that adhere to established purification standards and maximum trace thresholds. The risk to the consumer is considered negligible when products are formulated correctly.