On checking out a suspect claim--jk

On reading this article in Wikipedia, I became suspicious of the claim that propylene glycol caused vaginal irritation in menopausal women because of unusual presumptions:  1) that the irritation occurred only in menopausal women[i]; 2) that propylene glycol would continue to be the chief lubricant when there are suitable alternatives that the manufacturers could use.  Given these two red flags, I decide to check the source (citation) in the Wikipedia article.  The title Screaming to be Heard:  Hormonal Connections that Women Suspect and Doctors Ignore, indicates that the book is marketed to the public at large.  Such books, lacking peer review, target an audience who are skeptical of “establishment science” and religiously subscribe to “alternative medicine”. 

These popular books make claims that go beyond the evidence.  I therefore decided to see what the medical literature has on this alleged problem.  www.scholar.google.com is the best scientific search engine.  I searched four headings.  First propylene glycol + lubricant and propylene glycol + ointment; and Elizabeth Vliet. Nothing came up concerning the alleged problem in menopausal women.  Then I tried the author Elizabeth Vliet.  She appears as coauthor in an article on osteoporosis published in 2005, and her book also showed up with 11 citations.  The citations of her book were not for the alleged menopausal problem.  Having reached a dead end, I decided not to go to the book itself—enough time had already been consumed.  I thus concluded that this problem is most likely rare if at all, and any reports of such connection were probably based on a coincidental rather than causal connection. 

     As a lubricant for sexual, propylene glycol fails:  It dries out within a minute.  For sex there are special lubricants, most of which have as its base mineral oil.  I have known women who use baby oil, mineral oil, vegetable oil, and Vaseline.  They don’t dry out. 

http://www.reference.com/search?q=propylene%20glycol & Wikipedia.org

1,2-Propanediol
Methyl ethylene glycol
1,2-Dihydroxypropane
C₃H₈O₂ / CH₃CHOHCH₂OH
Molecular mass: 76.09

A diol alcohol, melting point -59°C, boiling point 188.2° C

The U.S. Food and Drug Administration has determined that propylene glycol in or on cat food has not been shown by adequate scientific data to be safe for use. Use of propylene glycol in or on cat food causes the feed to be adulterated and in violation of the Federal Food, Drug, and Cosmetic Act. 21CFR589.1001

The U.S. Food and Drug Administration (FDA) has determined propylene glycol to be "generally recognized as safe" for use in food, cosmetics, and medicines. Like ethylene glycol, propylene glycol affects the body's chemistry by increasing the amount of acid. Propylene glycol is metabolized into lactic acid, which occurs naturally as muscles are exercised, while ethylene glycol is metabolized into oxalic acid, which is toxic.  {Oxalic acid forms calcium oxalate and thereby removes calcium from the body.  In sufficient amounts it is disruptive of various cellular process).

Post menopausal women who require the use of an estrogen cream may notice that brand name creams made with propylene glycol often create extreme, uncomfortable burning along the vulva and perianal area. In these cases, patients can request that a local compounding pharmacy make a "propylene glycol free" cream which is much more tolerable. {Source Elizabeth Vliet MD, Screaming To Be Heard: Hormonal Connections That Women Suspect and Doctors Ignore". M. Evans and Company, Inc. New York 1995, which is hardly scientific work.  Moreover a Scholargogle.com search failed to find other articles that supported this claim—jk}  

Patients with vulvodynia and interstitial cystitis may be especially sensitive to propylene glycol. Women struggling with yeast infections may also notice that some OTC creams can cause intense burning.

KY Dutch Message 2-1, for lover is primary ingredient is propylene glycol--jk. 

Propylene glycol is used:

• As a moisturizer in medicines, cosmetics, food, toothpaste, mouth wash, and tobacco products
• As a medical and sexual lubricant (A.K.A. "personal lubricant")
• As an emulsification agent in Angostura and Orange bitters
• As a solvent for food colors and flavourings
• As a humectant food additive, labeled as E number E1520
• As a carrier in fragrance oils
• As a non-toxic antifreeze
• In smoke machines to make artificial smoke for use in firefighters' training and theatrical productions
• In electronic cigarettes to make the produced vapor better resemble cigarette smoke
• In hand sanitizers, antibacterial lotions, and saline solutions
• As a main ingredient in many cosmetic products, including baby wipes, bubble baths, deodorants, shampoos, and hair dyes
• As a base ingredient in aircraft deicing fluid and some automobile antifreezes
• In cryonics
• As a working fluid in hydraulic presses
• To regulate humidity in a cigar humidor
• As the killing and preserving agent in pitfall traps, usually used to capture ground beetles
• To treat livestock ketosis

Propylene glycol is non-toxic and has similar properties as ethylene glycol (MEG). The industrial norm is to replace ethylene glycol by propylene glycol.

Propylene glycol has very low toxicity.  In one study rats feed contained 5% propylene glycol over a period of 104 weeks with no apparent ill effects.  In humans toxicity requires a plasma level of over 4g/L.  Thus it is recognized as safe by the FDA.  It is widely used as a moisturizer in medicines, cosmetics, food, toothpaste, and tobacco products.  It is used as a moisturizer in sexual lubricants (the subject of the article below).  It is the principle ingredient in automotive anti-freeze.