Propylene Glycol & Glycol Ethers

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Common Solvent Propylene Glycol may pose a wider range of health effects on human health than previously known.

Propylene Glycol and Glycol Ethers, commonly known as PGEs, result from the reaction of propylene oxide with a varied chain of alcohols.

The PGE family of chemical compounds is based on a similarity in molecular, structural and physicochemical properties. Clear, viscous, colourless liquids at room temperature that have very little odour, a slightly bittersweet taste, and low vapour pressures amid superior solvent properties (totally miscible with water and a great variety of organic solvents), and biodegradable according to Lyondell [1].

These chemicals are manufactured as co products and are used commercially in a large variety of industrial and commercial goods. They are available as highly purified produce which meet well-defined manufacturing and sales specifications.

PGEs' great degree of solvency and lower volatility makes them valuable as coupling, coalescing, and dispersing agents; multiple indoor sources emit PGEs, they are widely used in water-bases paints, inks, varnishes, resins, dyes, lacquers, cleaning fluids, agricultural chemicals and other oils and greases, pesticides. Non solvent uses for PGEs include hydraulic and brake fluids, anti-acing agents, PVC pipes and artificial theatrical smoke.

When produced according to specific guidelines, PGs are legally permitted as a direct additive for processed foods and are classified as safe.  Because of their low human toxicity (however, overexposure or spillage during handling should be strictly avoided as a matter of good safety practice) and desirable formulation properties they are a frequently used additive in cosmetics, personal care products from shampoo, soaps, creams, ointments, deodorant and toothpaste to laundry detergents and floor wax and pharmaceutical products.  PG is used in food such as cake mixes, salad dressings, soft drinks, popcorn, food colourings, fat-free ice cream and sour cream. It also protects food from freezing and helps as a preservative. In food PG is listed as E 1520, in cosmetics as such in the ingredient list but for industrial applications there is no requirement for propylene glycol to be labelled.

Once PGEs are introduced by inhalation or oral exposure, they are rapidly absorbed and distributed throughout the body.  Dermal absorption is to some extent slowed but subsequent distribution is rapid.  PGEs leave the body via urine and expired air and a small portion is excreted in the faeces.

However, recent research by Harvard University and Sweden's Kalstad University 'Common Household Chemical and the Allergy Risks in Pre-School Age Children' has emphasized the potential of a link between the presence of PGEs and asthma, allergies and eczema in children.

The researchers were looking for a combination of very specific volatile organic compounds VOCs (8 in fact) in the home, gases that are emitted from liquids or solids and which can damage the environment and human health, and sought to investigate the risk they pose in indoor air.

In the county of Varmland, Sweden the target population for the study were 400 developing children where nearly half of the children reported at least two symptoms of wheezing, rhinitis and eczema in 2 separate questionnaires sent one and a half years apart, and the other half were healthy.

Samples or air and dust were collected from the room where the children most often slept. The results showed that concentration of PGEs, but no other classes of VOCs, was significantly higher among the children with rhinitis, and were twice as high as the concentration found in rooms of the children with no symptoms.

The objective of the investigation was to study the effects of VOCs in the home, but only PGEs in indoor air significantly increased the risks of allergic and respiratory symptoms. Due to the similarity of the PGEs compounds, and their overall low concentrations, it was not possible to identify the risk of the individual PGE compounds.

On the other hand, results of the study concluded that PGE-outcome associations are not merely linked with frequent cleaning, which suggests that building products are the cause of the symptoms.

A previous study of house painters (1989-1991) who were exposed to water-based paints, reported significantly higher incidence of chest tightness/wheezing, airway irritation, bronchial hyper-responsiveness, and shortness of breath.  And in a non-occupational situation, greater chance of asthma symptoms were observed in adults exposed to a newly painted wood or kitchen surfaces, and/or synthetic material-based furniture.

Although the research by Harvard University and Sweden's Kalstad University demonstrates that the bedroom concentration of PGEs are much associated with the risks of multiple allergic symptoms, rhinitis and eczema, and sensitisation in preschool age children, a full extent experimental model and more testing should be carried out to validate the results and to clarify the effects of PGEs in developing children.

ecospecifier note: "PGEs being such a broad family of chemicals span several classifications within ecospecifiers Cautionary Assessment Process (ES CAP). They are normally classified in categories 1, 2 and 3 depending on the specific chemistry.  ES CAP is based on the precautionary principle and as a result of this research, ecospecifier will subject to standard ES CAP risk analysis, in future attach as cautionary 'Issue of Concern' statement to all PGE compounds in Verified Product assessments and GreenTag Certifications, where the risks shown in these studies are 'likely to occur' or greater".

David Baggs. CEO & GreenTag Program Director.

 

[1] Lyondell Chemical Company. 'Environmental Aspects Report, Comparative Biodegradation of Propylene Glycol Ethers'. 2006.  Click here to see report.

Lyondell and Basell merge in 2007 to become LyondellBasell Industries - visit their website for more information. www.lyondellbasell.com

[2] UNEP Publications. 'Propylene Glycol Ethers'. November 2003. Click here to view publication.

[3] Choi H, Schmidbauer N, Sundell J, Hasselgren M, Spengler J, et al. 'Common Household Chemicals and the Allergy Risks in Pre-School Age Children'. Harvard University and Sweden's Kalstad University. October 18, 2010.  Click here to see full paper.

 

Author: Eliana Tovar-Molina

© ecospecifier 2011