Oleth-5 has a Natural Origin Index (NOI) of 0.55 (scale 0–1) per ISO 16128. Oleyl alcohol is an unsaturated oleochemical fatty alcohol derived from oleic acid; the five ethylene-oxide units are petrochemical. An NOI of 0.55 means 55% of its molecular mass is traceable to a natural, renewable source.

Is Oleth-5 natural? NOI 0.55 — Is That Natural?

How we scored it

Oleyl alcohol C18H36O 268 Da (oleochemical, from oleic acid) + 5 EO C2H4O 220 Da (petrochemical) = 489 Da total; 268/489 = 0.55.

What counts. ISO 16128-2 scores the atoms that remain in the final ingredient. Reagents, solvents, catalysts and protecting groups used during manufacture leave no mass behind and are not counted.

Where it comes from

Made by ethoxylating oleyl alcohol, reduced from vegetable-oil-derived oleic acid, with 5 moles of petrochemical ethylene oxide. The unsaturated C18:1 chain makes a synthetic petrochemical alcohol source uncommon.

In plain English

An emulsifier that blends oil and water, made from plant-oil-derived oleyl alcohol reacted with ethylene oxide. Helps keep lotions and creams smooth and stable.

CosIng definition: Poly(oxy-1,2-ethanediyl), .alpha.-9-(Z)-octadecenyl-.omega.-hydroxy (5 mol EO average molar ratio)

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References

1ISO 16128-1:2016 and ISO 16128-2:2017 — Guidelines on technical definitions and criteria for natural and organic cosmetic ingredients and products. ISO, Geneva.
2OLETH-5. CosIng — European Commission cosmetic ingredient database. ec.europa.eu/cosing ↗
3OLETH-5. CosIng u2014 European Commission database for information on cosmetic substances and ingredients. https://ec.europa.eu/growth/tools-databases/cosing/search?search=OLETH-5