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ToxicFree Foundation / Ingredient Database / Propanediol
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    What is it?

    Propandediol has received some bad press due to its same Empirical Formula to Propylene Glycol, but Propanediol is distinctly different than Propylene Glycol in several ways:


    Propanediol and Propylene Glycol have the same Empirical Formula (C3H8O2), however the molecular structure of each compound is different. 

    INCI name Propanediol = Chemical name 1,3 Propanediol molecular structure: 


    INCI name Propylene Glycol = Chemical name 1,2 Propanediol molecular structure: 




    It is the structural difference between Propanediol and Propylene Glycol that makes the two compounds distinctly different. Therefore, each compound: 

    - is listed separately in the Personal Care Products Counsel International Cosmetic Ingredient 

     Dictionary and Handbook monographs 

    - has a different International Nomenclature Cosmetic Ingredient (INCI) name 

    - has a different Chemical Abstracts Services (CAS) number 

    - has a different European Inventory of Existing Chemical Substances (EINECS) number 

    - has a different European List of Notified Chemical Substances (ELINCS) number. 


    The structural difference between Propanediol and Propylene Glycol cause them to each have 

    different physical and chemical properties: 

                                                               Propanediol                 Propylene Glycol 

    Boiling Point                                         214C                           188.2C 

    Melting Point                                       - 25C                            - 60C 

    Density                                                 1.053 @ 20C                 1.0361 @ 20C 

    Vapor Pressure                                   0.044mm Hg @ 25C     0.129mm Hg @ 25C

    Flash Point                                           268C                            99.04C 

    Autoingintion                                       400C                            371C 

    (Note that the Flash Point of Propanediol is significantly higher than that of Propylene Glycol. Flash Point is defined as the lowest temperature at which a material can vaporize to form an ignitable mixture in air.)

    The physical and chemical differences between Propanediol and Propylene Glycol cause the two compounds to have different toxocology profiles.



    - Propanediol is mainly derived from a sustainable and renewable corn sugar fermentation 


    - Propylene Glycol is mainly synthesized from Propylene Oxide, a petrochemical. 

    - Manufacturing corn-derived Propanediol emits up to 40% less greenhouse gases than 

    chemically-derived Propylene Glycol1

    - Corn-derived Propanediol uses up to 35% less non- renewable energy than chemically-derived 

    Propylene Glycol1

    According to life cycle analysis from design data by Dupont Tate & Lyle


    More Information

    Glycols have been used in cosmetics and personal care products to impart beneficial properties such as humectancy, solvency, moisturization and emulsification. One such ingredient is 1,3-propanediol (PDO), which is manufactured either by a chemical process using petroleum feedstock or by a fermentation (bio-based) process using corn sugar. Since PDO became commercially available only recently, it does not yet have a widespread history of use for properties such as humectancy, moisturization or emulsification. However, a substance structurally similar to PDO, propylene glycol (PG), does have widespread use and distribution in personal care products—but it also has a history of some dermal irritation and to a lesser extent, sensitization.

    Obviously, besides the efficacy properties of a raw material, another critical property is the lack of or low potential for dermal irritation and sensitization of skin. Therefore, an evaluation of the potential for new ingredients to cause adverse skin reactions is essential. Information from previous animal studies following exposure to chemically-produced PDO suggests a low potential for human skin reactions. This historical information includes a study in rabbits (Draize method), showing neat PDO is mildly irritating; and a study in guinea pigs (Landsteiner/Draize method), showing no dermal irritation or sensitization.

    To learn more about the possible effects of 1,3-Propanediol on the skin, follow the link:

    This ingredient is commonly used in: