Polysorbate 40 (Polyoxyethylene sorbitan monopalmitate) is a chemical compound produced by the reaction of lauric acid, ethylene oxide and sorbitol through ethoxylation of sorbitan monolaurate. Polysorbate is a sugar alcohol, sorbitol, which is transformed into sorbitan by a dehydration process and then passes through ethoxylation before lauric acid is added. The number 40 indicates the molecule with 40 repeated polyethylene glycol units.

It appears as a white powder or as a stable yellowish viscous liquid. Incompatible with strong oxidising agents. Soluble in water, ethanol, methanol, carbinol, isopropanol, isopropyl alcohol and other solvents, insoluble in mineral oil.

What it is used for and where

Chemical auxiliary agent, chemical intermediate, hydrophilic and non-ionic surfactant. Generally regarded as a fatty acid ethoxylated sorbitan ester.

Food

Ingredient included in the list of European food additives as E434 with an emulsifying function.

Cosmetics

Surfactant - Emulsifying agent. Emulsions are thermodynamically unstable and are used to soothe or soften the skin and emulsify, so they need a specific, stabilising ingredient. This ingredient forms a film, lowers the surface tension and makes two immiscible liquids miscible. A very important factor affecting the stability of the emulsion is the amount of the emulsifying agent. Emulsifiers have the property of reducing the oil/water or water/oil interfacial tension, improving the stability of the emulsion and also directly influencing the stability, sensory properties and surface tension of sunscreens by modulating the filmometric performance.

Surfactant - Cleansing agent. Cosmetic products used to cleanse the skin utilise the surface-active action that produces a lowering of the surface tension of the stratum corneum, facilitating the removal of dirt and impurities. 

Safety

The  Joint Food  and  Agriculture  Organization  of  the  United  Nations  (FAO)/World  Health Organization (WHO)Expert Committee on Food Additives (JECFA)derived an Acceptable Daily Intake (ADI) of  25mg/kg body  weight  (bw)/day  (group  ADI  for  polysorbates  20,  40,  60,  65  and  80) and the Scientific Committee  on  Food  (SCF) derived  a  group  ADI  of  10mg/kg  bw/day.  Small  amounts of polyoxyethylene sorbitansare absorbed. Similar toxicokinetics would be expected for all polysorbates based on their similarities in  structure  and  metabolic  fate.  The  acute  toxicity  is  very  low.  There  is no  concern  regarding  genotoxicity, carcinogenicity or developmental  toxicity.  From a limited number of studies,there  is  no  indication of reproductive  toxicity. The Panel recommended that the  maximum limits  for the  impurities of toxic elements  (arsenic, lead, cadmium  and  mercury)  in  the  EC specification  for  polysorbates  (E432–E436)  should  be  revised  in order to ascertain that polysorbates (E432–E436) as food additives will not be a significant source of exposure to those toxic elements in food  (1).

• Molecular Formula   C₂₆H₅₀O₁₀ 
• Molecular Weight   522.7 g/mol
• CAS  9005-66-7
• UNII   STI11B5A2X
• EC Number   

References____________________________________________________________________

(1) EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS), 2015. Scientific Opinion on the re‐evaluation of polyoxyethylene sorbitan monolaurate (E 432), polyoxyethylene sorbitan monooleate (E 433), polyoxyethylene sorbitan monopalmitate (E 434), polyoxyethylene sorbitan monostearate (E 435) and polyoxyethylene sorbitan tristearate (E 436) as food additives. Efsa Journal, 13(7), p.4152.