Dipropylene Glycol
Dipropylene glycol (DPG): Features
Dipropylene glycol (DPG, CAS no. 25265-71-8, EC n. 246-770-3) is a chemical substance made up of two linked propylene glycol units. Representative chemical structure of DPG (obtained from PubChem) is presented below. Carbon (C) atoms are represented by gray balls, oxygen (O) atoms by red balls and hydrogen (H) atoms by white balls.
Dipropylene glycol has a high boiling point and therefore a very low vapour pressure. As it also has very low toxic properties, DPG does not require special handling precautions. DPG is a colourless liquid with low odour properties, with low flammability and low vapour pressure properties. It is soluble in water.
It is stable molecule with a long-standing reputation for safe use as carrier solvent for personal care products, and in industrial applications.
Dipropylene glycol (DPG): Personal Care Markets
DPG helps improve the quality of every-day life in many personal care products such as fragrances and deodorants, face make-up, nail polish, soaps, shaving and skin-care products. DPG is manufactured and handled according to high industry standards applicable for the intended personal care products uses.
DPG is found on European cosmetic ingredient listing (CosIng) with the following link: https://ec.europa.eu/growth/tools-databases/cosing/details/75742
Dipropylene glycol (DPG): Safety
DPG has low flammability, low vapour pressure, is soluble in water, is biodegradable and has very low toxic properties, therefore DPG does not require any special handling precautions.
Dipropylene glycol (DPG): Regulatory
Dipropylene glycol toxicity has been thoroughly tested and found to be non-hazardous to human health and the environment under normal conditions of use. DPG is biodegradable in the environment.
Food Contact
In accordance with Regulation (EU) 2023/1627 on plastic materials and articles intended to come into contact with food). DPG is authorised for use as an additive, polymer production aid, monomer, or other starting substance in the production of plastic materials and articles intended to come into contact with food, such as packaging material.
The United States Food & Drug Administration (FDA) has approved the use of DPG in various indirect food contact applications as specified in 21 CFR parts 175, 176, 177 or 178. Dipropylene glycol is used in food contact surfaces such as adhesives and components of coatings, paper and paperboard components, polymers, defoaming agents in coatings and surface lubricants used in the manufacture of metallic articles that contact food.
Cosmetics
In Europe Regulation, (EU) 2023/1490 on Cosmetic Products (Cosmetics Regulation) works on the principle of a “negative” list which defines substances that are prohibited or restricted for use in cosmetics and DPG is not on this list. It can be found on CosIng database with no restrictions. (https://ec.europa.eu/growth/tools-databases/cosing/details/75742).
In the US a 2006 safety assessment published by the Cosmetics Ingredients Review (CIR) listed DPG as a safe ingredient in cosmetics up to a concentration of 50 %.
Classification
Most countries have adopted the UN Globally Harmonised System (GHS) for Classification and Labelling. In Europe GHS is implemented under Regulation (EC) No 1272/2008, also known as the CLP (Classification, Labelling and Packaging) Regulation. In the United States GHS is implemented under the OSHA Hazard Communication Standard (HCS). Dipropylene glycol is not classified as hazardous under GHS.
Dipropylene glycol (DPG): Health Summary
Non-hazardous Substance
Humans are exposed to DPG primarily through skin contact and incidental inhalation of vapours and aerosols. Dipropylene glycol is expected to be readily absorbed by oral exposure but a study using human skin found negligible absorption for dermal exposure. Inhalation exposure to significant quantities of DPG is not expected. Studies on the metabolism of structurally similar propylene glycols indicate that in the body DPG will readily break down to PG and then to carbon dioxide.
Studies show that DPG has a very low degree of acute toxicity. It is non-irritating to the eye and skin with no evidence of allergic skin reactions. In long term studies conducted in laboratory animals, some organ effects were noted but these were of questionable biological significance and occurred at very high dose levels of low relevance to human exposures. Tests have shown DPG is not carcinogenic or genotoxic, nor does it affect fertility or reproduction.
In the environment, the low Log Kow value for DPG indicates this substance will tend to partition to aqueous phases and a low potential for bioaccumulation. Dipropylene glycol is readily biodegradable in fresh water and biodegrades in seawater and is not expected to be persistent in the environment. Based on test data on DPG and structurally similar propylene glycols in aquatic organisms, DPG is demonstrated to be a low concern for ecotoxicological hazards.