Benefits and Applications
Pharmaceuticals
As a result of its low vapour pressure, low toxicity, low flammability and high purity, propylene gycol USP is cleared for use in the United States in accordance with U.S. FDA requirements. In Europe the product is approved by the European Pharmacopoeia for use in pharmaceuticals as an excipient.
Direct and Indirect Food Contact
U.S.A.
Cleared for Direct food use (added to an edible material) when in compliance with any prescribed limitations, as Generally Recognised as Safe ( GRAS) under the following paragraphs:
21 CFR 184.1666 Propylene Glycol
21 CFR 582. 1666 Substances Generally Recognised As Safe (except in cat food)
21 CFR 582.4666
Cleared for Indirect food contact:
21 CFR 175.105
21 CFR 175.300
21 CFR 175.320
21 CFR 176.170
21 CFR 176.210
21 CFR 177.1680
40 CFR 180.1001(c) (e)
40 CFR 182.99
Europe
In Europe, Propylene Glycol is not approved as a general-purpose food grade product or direct food additive for human consumption. However, it is regulated by Directive No 95/2/EC and has been assigned E-number E1520:
- As a carrier/carrier solvent for colors, emulsifiers, antioxidants and enzymes, with a maximum allowed level of 1 g/kg in the final foodstuffs
- In flavorings, with a maximum allowed level of 3 g/kg, from all sources in foodstuffs as consumed or reconstituted according to the instructions of the manufacturer, individually or in combination
- In flavorings for beverages, with the exception of cream liqueurs, with a maximum allowed level of 1 g/l
LyondellBasell Propylene Glycol USP/EP fulfills the purity criteria for E1520 as detailed in EU Directive 2008/84/EC dated August 27, 2008, which indicates specific purity criteria on food additives other than colors and sweeteners. As an animal feed material, it has the number 13.11.1 in the Catalogue for Feed Materials.
The product is cleared for indirect food contact under EC Council Directive 90/128/EEC of 23 February 1990 as amended through 96/11/EEC relating to plastic materials and articles intended to come into contact with foodstuffs.
Propylene glycol USP/EP is authorised as a Monomer or other starting Substance (section A). The PM/ REF Number is 23740 and 81840.
In France, propylene glycol USP/EP is in included in the French Positive List: Order of 27 Oct 1975, as amended through Order of 15 June 1993, regarding approved chemical substances for use in cleaning agents that come into contact with foodstuffs.
In Germany, the product is cleared for use in various applications. According to BgVV recommendations:
| XXI |
Articles prepared from natural synthetic rubber |
| XXII |
Acrylate and methacrylate block polymers |
| XXVIII |
Cross-linked polyurethanes as adhesives layers for food-packaging materials |
| XXXIX |
Articles based on polyurethanes |
| XLI |
Linear polyurethanes for paper coatings |
| XLIV |
Synthetic sausage skins |
Cosmetics and Toiletries
Propylene glycol is used in various cosmetics and toiletry products, such as shampoos, skin creams, deodorants and lipsticks.
Council Directive 76/768/EEC on the approximation of the laws of the member States relating to cosmetic products states that 'no person shall supply any cosmetic product which is liable to cause damage to the human health when it is applied under normal conditions of use, or under conditions which are reasonably foreseeable......'. The onus is on the manufacturer, therefore to establish that the cosmetic product is 'safe' and there are no lists of 'permitted chemicals'. A series of 'negative' lists indicate that certain materials must not be used in cosmetic products. Propylene glycol does not appear in any of these negative lists.
In 1994, Propylene glycol was reviewed in detail by the Cosmetic Ingredient Review Panel of the Cosmetic, Toiletries and Fragrances Association (CTFA), the panel concluded that MPG is safe for use - even at concentrations above those that actually appear in consumer products. The panel is a scientific committee that uses the expertise of dermatologists, toxicologists and other health scientists to assess the safety of cosmetic ingredients.
Animal feed additives
Propylene glycol is listed as a feed material (Regulation EC 767/2009); the registration in the European Catalogue of Feed Materials is 13.11.1. Propylene glycol should not be used in feline (cats and cat-like animals) feed.
Properties
Propylene glycol is a colorless, odorless and slightly viscous liquid. Because of its versatility propylene glycol is used in a variety of applications in aqueous solutions and over a wide temperature range. Some of the most commonly requested properties of propylene glycol and aqueous solutions of propylene glycol are available below.
Toxicology/Regulatory
The U.S. Food and Drug Administration has given propylene glycol the classification Generally Recognized as Safe (GRAS). It has been extensively studied and its toxicology has been summarized in a SIDS Initial Assessment Report (SIAR) with a recommendation for no additional study. This report will be published by the OECD on their website in the near future.
14-Day Cumulative Dermal Irritation Study
Storage and Handling
Due to its low vapor pressure, toxicity and flammability, Propylene glycol presents no special handling problems. However, overexposure or spillage should be strictly avoided as a matter of good safety practice. Propylene glycol may require storage facilities designed to prevent moisture intrusion because of its hygroscopic nature. Storage vessels and transfer lines of mild steel may be used if slight increases in color and trace iron levels are not objectionable. Stainless steel and/or mild steel vessels with baked phenolic or epoxy-phenolic linings are recommended to promote long-term storage and to maintain high quality. Exposure to ultraviolet light may cause degradation of the propylene glycol. Translucent or transparent drums and totes filled with propylene glycol should not be stored where they will be exposed to direct sunlight.
Guidelines for Distribution and Handling of Propylene Glycol USP/EP (published by the PO/PG Sector Group of the European Chemical Industry Council)
Manufacturing Facilities
High purity propylene glycol (PGUSP/EP) is manufactured at LyondellBasell locations in Pasadena, TX (United States), Fos sur Mer (France) and Botlek (Netherlands).
All sites have ISO 9001 certification and the Botlek site is also ISO 14001 certified.
Shelf Life
The shelf life of propylene glycol USP manufactured and delivered by LyondellBasell when stored and handled under appropriate conditions is two years. Subsequent handling and/or repackaging by intermediaries such as distributors may affect shelf life. Therefore, the user of this material should confirm this shelf life via testing or with their immediate supplier.
A formal study showed that propylene glycol is stable for at least two years at 25° C in steel drums lined with a baked epoxy phenolic coating and protected from moisture and air. On-going studies of propylene glycol held in glass at ambient or sub-ambient temperatures also show no degradation after two years. Users of propylene glycol USP are advised to consider their own shelf life studies as their conditions of storage and handling may very well deviate from those used by LyondellBasell.
Production Process
Propylene glycol USP/EP is produced by highly qualified personnel under strict rules which include a quality management system as well as high standards of manufacturing and handling to avoid contamination and minimize the risk of errors that could effect product quality.
Finished glycols are extensively tested to ensure they meet defined specifications. The propylene glycols manufacturing unit and storage facilities are dedicated for propylene glycol USP/EP. The product is always stored under nitrogen.
The manufacturing process is described in general terms as follows:
- Propylene oxide is reacted at 115 -140°C with a large excess of demineralised water to produce a mixture of mono, di and tri propylene glycols (MPG, DPG and TPG).
- Excess water is removed from the reactor effluent in a multiple effect evaporator system, the last evaporator being under vacuum. A stripper eliminates light impurities.
- Multiple stage vacuum distillation removes the remaining water and separates MPG from the other glycols.
- The process does not use any solvents other than water.
- The manufacture of LyondellBasell propylene glycol uses only water and materials of synthetic petrochemical origin and there are no additives in the finished product. Therefore, it contains no genetically modified organisms, gluten, or known allergens.
Since no organic solvents are used during the manufacturing process, MPG USP/EP is in compliance with CPMP/ ICH/283/95; "Residual solvents in pharmaceuticals for the safety of a patient."
- Propylene glycol USP/EP is always held in stainless steel containers or in containers constructed of carbon steel lined with an FDA-compliant coating and handled according to CEFIC and IPEC guidelines on USP.
Regulatory
General Inventory Listings: Propylene glycol is on the United States, European, Canadian, Korean, Australian, Japanese, Philippine and Chinese chemical inventories.
Europe
Propylene glycol is not classified under 67/548/EEC as a dangerous substance
Germany
The Water Endangering Class (WGK) is: 1 and Kenn. Number: 280, as from 1 January 2001.
Ireland
Irish Occupational Exposure Limit
Irish - 8 hour OEL (TWA) particulates is 10 mg/m3
Irish - 8 hour OEL (TWA) Total vapour and particulates is 150 ppm
Switzerland
Switzerland Federal Health Agency Giftliste 1 (stoffe), Ausgabe 1996
Toxicity Category: --
Swiss Identification Number: G - 2798
United Kingdom
UK. Health and Safety Executive EH40/98 Occupational Exposure Limits 1998
Particulates 10 mg/3
Vapour and particulates 150 ppm
United States
Propylene glycol is not subject to the reporting requirements of CERCLA. Propylene glycol does not contain any chemicals at levels subject to California Proposition 65. Propylene glycol is considered a Volatile Organic Compound by the USEPA.