If this has been posted elsewhere, my apologies. But I see the question come up over and over again regarding the safety of Propylene Glycol (PG). I discovered this document today, issued by the National Toxicology Program, Department of Health and Human Services
http://cerhr.niehs.nih.gov/chemicals/egpg/propylene/PG_Monograph.pdf
Crucial messages
Overall Toxicity:
"Clear evidence of no adverse effects"
Reproductive Risk:
http://cerhr.niehs.nih.gov/chemicals/egpg/propylene/PG_Monograph.pdf
Crucial messages
Overall Toxicity:
"Clear evidence of no adverse effects"
Reproductive Risk:
"The NTP concurs with the CERHR EG/PG Expert Panel that there is negligible concern for adverse developmental or reproductive toxicity from PG exposures in humans."