There are some here that intentionally and knowingly ingest mineral oil. A little more petroleum product in your liver, would be no big deal
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For Arthritis: What Is The Premise?
The premise seems simple enough, you spray or rub on a dose of WD-40 to free up stiff, painful arthritic joints just like they oiled up the Tin Man in the classic movie "The Wizard of Oz".
However, according to John C. Wolf, D.O., Ohio University College of Osteopathic Medicine, Family Medicine News (1998 archives), "In the case of WD-40, a great myth developed about its benefits in treating arthritis. It is easy to follow the flawed logic: WD-40 works wonders on stiff door locks, squeaky hinges, and rusted bolts. Therefore, it should make my stiff, sore, squeaking arthritic joints work better. Unfortunately, like all myths, this one isn't true."
WD-40 For Arthritis: Potential For Harm
A look at the WD-40 MSDS (Material Safety Data Sheet) shows that the product contains petroleum distillates. Skin contact may cause drying of skin and/or irritation. According to the WD-40 MSDS, it is advised to wash with soap and water if you have contact with your skin.
Greater risks can come from prolonged exposure. According to the article, WD-40 for Arthritis? by Katherine Poehlmann, Ph.D., "To date, no credible scientific studies have shown any benefit from the use of WD-40 for arthritis. In fact, there may be cumulative harmful effects."