Potassium Sorbate
Also known as Potassium sorbate, 2,4-Hexadienoic acid potassium salt, E202, Sorbistat-K
“CIR Expert Panel says: safe as used in cosmetics.”
Potassium sorbate (CAS 590-00-1; C6H7KO2; potassium salt of sorbic acid) is an EU Annex V-listed preservative (E202) widely used in cosmetics, food, and pharmaceuticals. The CIR Expert Panel assessed sorbic acid and its salts — including potassium sorbate — in 1988 (JACT 7(6):837-80) and reconfirmed the finding in April 2006; the QRT records an unconditional Finding=S with no detail or concentration cap. It is commonly paired with sodium benzoate in 'natural' preservation systems. Literature documents occasional non-immunologic immediate contact reactions (pseudoallergic urticaria-type responses) to sorbic acid at concentrations above 0.1%, distinct from true IgE-mediated allergy; immunologic sensitization (allergic contact dermatitis) is considered rare. Its EU Annex V status (maximum 0.6% as sorbic acid) could not be directly verified via CosIng SPA, so cosing is excluded from coverage scope.
CIR Expert Panel concluded safe as used in cosmetics:837-80, 1988; reconfirmed 04/06) — unconditional Finding=S with no concentration restriction
EU food-additive status (E202) and FDA GRAS (21 CFR 182.3640) for food use supports a long history of safe human exposure via multiple routes
Effective against yeasts, molds, and some bacteria; pairs well with sodium benzoate for broad-spectrum coverage in clean-beauty and 'natural' preservative systems
Markedly water-soluble; compatible with a wide range of cosmetic formulation types
Consumer-facing perception as a 'natural' or 'clean' preservative (derived from sorbic acid, found in nature) makes it popular in brands targeting clean-beauty positioning
Non-immunologic immediate contact reactions (pseudoallergic/urticarial) to sorbic acid reported at concentrations above ~0.1%; these are dose-dependent vasodilatory reactions, not true IgE allergy — documented by Ramsing and Menne (1993, PMID 8458215) and historically in Fisher (1980)
pH-dependent activity: potassium sorbate (like sorbic acid) is most effective as a preservative at low to moderately acidic pH (below ~6.5); antimicrobial efficacy decreases substantially in neutral or alkaline formulations
Potential for true allergic contact dermatitis is low but documented in isolated case reports; sorbic acid is not a standard patch test allergen in most screening batteries, suggesting low prevalence in the general population
EU Annex V limits potassium sorbate to a maximum 0.6% as sorbic acid (E202); this cap could not be verified directly via CosIng (SPA barrier) and is excluded from regulatory entries but formulators should apply it when selling in EU
CIR Quick Reference Table (12/2017, revised 07/2018) — POTASSIUM SORBATE row: Finding=S (Safe), Detail=blank, Citation=JACT 7(6):837-80, …
“Potassium Sorbate | S | [blank detail] | JACT 7(6):837-80, 1988 confirmed 04/06”— QRT-122017revised072018.pdf, Potassium Sorbate row