Label Check: PEGs

This is the 4th installment in my Label Check series, in which I examine a toxic ingredient in depth.
PEGs (polyethylene glycol) is a petroleum-based product that has many uses and applications, from laxatives, to medicinal solvents and lubricants, and eye drops. PEGs can also be found in skin creams, toothpastes, and personal lubricants.  PEGs dissolve grease and oil. So by dissolving our skin's natural oils, they make our skin more vulnerable to other toxins. The structure of polyethylene glycol is below. The "n" denotes the number of repeating units.

Image from http://upload.wikimedia.org/wikipedia/commons/4/42/Polyethylene_glycol.png

According to Truth in Aging:

"In cosmetics, PEGs function in three ways: as emollients (which help soften and lubricate the skin), as emulsifiers (which help water-based and oil-based ingredients mix properly), and as vehicles that help deliver other ingredients deeper into the skin."

There are multiple forms of PEGs. In labels, you will see the letters PEG often followed by a number.  The number tells the molecular weight. PEGs with a lower molecular weight can penetrate the skin more easily.  For example, PEG-8 has a lower molecular weight than PEG-100.

You also often see PEGs on the label as PEG-2 stearate. The stearate shows that the compound polyethylene (plastic) + glycol (alcohol) attached to a stearic acid molecule. Stearic acid, is a naturally occurring fatty acid, often from vegetable oil.

According to the Skin Deep Database, polyethylene glycol, may be contaminated with the carcinogens 1-4 dioxane and ethylene oxide. Consider this with PEGs skin penetrating properties.

Skin irritation due to PEGs will depend on the condition of your skin. Again from Truth in Aging: 

"To note, independent of molecular size, PEGs of all sizes may penetrate through injured skin with compromised barrier function. So it is very important to avoid products with PEGs if your skin is not in tip top condition.

This penetration enhancing effect is important for three reasons: 1) If your skin care product contains a bunch of other undesirable ingredients, PEGs will make it easier for them to get down deep into your skin. 2) By altering the surface tension of the skin, PEGs may upset the natural moisture balance. 3) PEGs are not always pure, but often come contaminated with a host of toxic impurities."

Check labels carefully to avoid products with PEGs, especially if you skin has any cuts, abrasions or openings.