Oleth-40 has a Natural Origin Index (NOI) of 0.13 (scale 0–1) per ISO 16128. Small natural oleyl-alcohol fragment heavily diluted by a very long 40-unit petrochemical ethylene oxide chain. An NOI of 0.13 means 13% of its molecular mass is traceable to a natural, renewable source.

Is Oleth-40 natural? NOI 0.13

How we scored it

Oleyl alcohol 268.5 Da (natural) + 40xEO 44.05=1762.1 Da (petrochemical) -> total 2030.6 Da; 268.5/2030.6 = 0.13.

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 oleochemical oleyl alcohol with petroleum-derived ethylene oxide to high EO count for water solubility. Cosmetic-grade oleyl alcohol is typically oleochemical.

In plain English

A cleansing surfactant made from natural oleyl alcohol reacted with 40 units of ethylene oxide, a petrochemical building block. The long ethylene oxide chain makes it very water-soluble for cleansing products.

CosIng definition: Poly(oxy-1,2-ethanediyl), .alpha.-9-(Z)-octadecenyl-.omega.-hydroxy (40 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-40. CosIng — European Commission cosmetic ingredient database. ec.europa.eu/cosing ↗
3OLETH-40. CosIng u2014 European Commission database for information on cosmetic substances and ingredients. https://ec.europa.eu/growth/tools-databases/cosing/search?search=OLETH-40