Question 1

What does Peg-400 do in a cosmetic formula?

Accepted Answer

This ingredient is a water-miscible solvent and humectant used to dissolve actives, improve spread, and help formulas retain moisture.

Question 2

Is Peg-400 clean?

Accepted Answer

Clean-beauty programs often flag it because it is made through ethoxylation and can carry trace process residues such as 1,4-dioxane if purification is weak. It is generally low-irritation at cosmetic use levels, but its restricted-list friction is real.

Question 3

Is Peg-400 sustainable?

Accepted Answer

This material is synthetic and usually petroleum-derived, although bio-based routes to some starting materials exist. It is highly water soluble, and lower molecular weight grades can biodegrade under aerobic conditions, but its fossil feedstock and processing profile weaken its sustainability fit.

Question 4

Is Peg-400 COSMOS-approved?

Accepted Answer

It is not permitted in COSMOS-natural or COSMOS-organic formulas because ingredients made by ethoxylation are outside the standard. From a Green Chemistry view, the main drawbacks are fossil feedstocks, reactive gas processing, and residue controls, despite useful functionality and water miscibility.

Question 5

How does Peg-400 work chemically?

Accepted Answer

The molecule is a low-molecular-weight, linear polyether with an average mass around 380 to 420 Da, making it a clear, viscous liquid that mixes readily with water, alcohols, and many glycols. It is typically used around 1 to 10% in leave-on cosmetics as a solvent or humectant, is stable across common cosmetic pH ranges, and can form peroxides with prolonged heat, light, or air exposure.