Polyquaternium-10

What it is

Polyquaternium-10 is a cationic, that is positively charged, cellulose-based polymer — chemically a quaternised hydroxyethyl cellulose. The starting material is cellulose, a plant-derived base that is chemically modified. Its origin is therefore semi-synthetic. That is factual information, not an assessment.

In hair products it provides conditioning, antistatic behaviour, easier combing and part of the consistency. The mechanism is worth noting: when diluted with water, the positively charged polymer forms a complex with the negatively charged surfactants that deposits selectively on the hair (technical term: coacervation). This is why the ingredient works even in products that are rinsed out again.

Why

• Molecule size: Polyquaternium-10 is a large polymer. Molecules of this size can barely penetrate the outer layer of the skin, so systemic uptake is very unlikely and exposure stays superficial.
• Method of application: in shampoos this is a rinse-off product — brief contact, then washed off. That is the exposure scenario with the lowest burden.
• Body of experience: the ingredient has been in broad use for decades. It does not feature notably as a contact allergen in the dermatological literature.

When the assessment differs

• Eye contact: cationic substances can be more irritating at the eye than on the skin. With shampoos this is the relevant point of contact, usually transient and mild.
• Leave-on products: in sprays or creams that stay on the hair, exposure lasts longer. This does not fundamentally change the assessment, but the context is different.
• Concentration: without the use level, strictly speaking only a statement about the substance property is possible, not a risk statement for a specific product.
• Environment: cationic polymers are judged differently regarding aquatic compatibility and degradability. How robust the data is for this substance specifically was not examined here. That belongs in a separate environmental assessment, not in the skin assessment.

Open questions

• Regulatory status: no maximum level and no annex reference are quoted here at second hand. For a reliable statement, the entry in the EU CosIng database must be checked, with its date.
• US Cosmetic Ingredient Review assessment: the wording is not available here and has not been quoted.
• Concentration in a specific product: not available.
• Environmental data: not examined.

Related substances

Applies to: Cationic conditioning agents

• Behenamidopropyl Dimethylamine — Conditioner, antistatic agent
• Behentrimonium Chloride — Cationic conditioner, detangler
• Cetrimonium Chloride — Emulsifier, conditioner
• Polyquaternium-7 — Cationic conditioning polymer

Further substances from the same group for which a long-form assessment already exists.