Let's see if we can put this issue to rest:
According to the EPA's 2006 review of propylene glycol, it has been registered as a general use antimicrobial in air conditioning units and air purifiers since 1950. The EPA stated that propylene glycol is of "low toxicity," meaning that acute toxicity symptoms in rats occur when they orally ingest more than 3,600 to 20,000 mg per pound of body weight(!). (In rabbits, the lower limit is 10,000mg per pound of body weight.)
The EPA indicates that propylene glycol is a non-irritant for eyes and skin.
Under the heading "General Toxicity Observations," the EPA states that "Upon reviewing the available toxicity information, the Agency has concluded that there are no endpoints of concern for oral, dermal, or inhalation exposure"
Under the heading "Carcinogenicity Classification," the EPA states that propylene glycol is "negative for carcinogenicity"
Under the heading "Mutagenicity Potential," which refers to its ability to induce genetic mutations, the EPA states that propylene glycol is "found to be negative" in tests for mutagenic or genotoxic potential.
Under the heading "FQPA Safety Factor," which adjusts toxicity estimates by a "10-fold safety factor (10X), to protect for special sensitivity in infants and children" when there is incomplete data: "The FQPA Safety Factor has been removed (i.e., reduced to IX) for propylene glycol... because there is no pre- or post-natal evidence for increased susceptibility following exposure. Further, the Agency has concluded that there are no endpoints of concern for oral, dermal, or inhalation exposure to propylene glycol... based on the low toxicity observed in studies conducted near or above testing limit doses"
The EPA's 2006 review of propylene glycol states 5 different times that "there are no endpoints for concern for oral, dermal, or inhalation exposure to propylene glycol."
The EPA states that propylene glycol is approved by the FDA for use in alcoholic beverages, confections and frostings, frozen dairy products, seasonings and flavorings, nuts and nut products, and all other food categories.
So, some people may be allergic to it. Shoot, I'm allergic to animal dander. But propylene glycol will not make you sick.
I keep hearing people say, "It's better just to breath oxygen." This may sound good as a common-sense assertion, but it does not bear scrutiny. The Earth's atmosphere is about 78% nitrogen and only about 20% oxygen (with 1% argon and 0.03% carbon dioxide). If breathing slightly less oxygen were bad for you, then living at a higher elevation would be hazardous to your health and minor variations in elevation above sea-level would impact your health.
Anyone who argues against the safety of propylene glycol based on its use in antifreeze is either ignorant or arguing in bad faith. To say that propylene glycol is an effective component in antifreeze is simply to say that it is highly water soluble. Dissolving anything in water lowers its freezing point (salt-water freezes at a lower temperature because it's salt dissolved into water). The the more of a substance that you can dissolve in water, the lower the freezing point of the resulting water-based solution. Since you can dissolve a heck of a lot of propylene glycol in water, it is highly effective in antifreeze.
Furthermore, the argument that propylene glycol is unsafe because it is an ingredient in antifreeze runs afoul of the fallacy of division, which mistakenly takes the properties of the whole to be properties of its components; e.g., an egg is white; and egg has a yolk; therefore a yolk is white. From the fact that some antifreeze is toxic, it does not follow that any single ingredient is toxic. Some glass cleaners contain vinegar. That doesn't make vinegar toxic.
Incidentally, the EPA has registered propylene glycol as an antimociobial for the following microbes: "Odor-causing bacteria, Fleas, Mites, Red lice, Animal pathogenic bacteria (G- and G+ vegetative), Shigella bacteria, Pasteurella bacteria, Listeria bacteria, Herpes Simplex I and II, Animal viruses, Influenza Virus A2, Aspergillus Niger Fungus, Mold/Mildew, Pseudomonas SPP., Shigella Flexneri, Shigella Sonnei." Sounds better than a flu shot.
The full text is available here: http://www.epa.gov/oppsrrd1/REDs/propylene_glycol_red.pdf
According to the EPA's 2006 review of propylene glycol, it has been registered as a general use antimicrobial in air conditioning units and air purifiers since 1950. The EPA stated that propylene glycol is of "low toxicity," meaning that acute toxicity symptoms in rats occur when they orally ingest more than 3,600 to 20,000 mg per pound of body weight(!). (In rabbits, the lower limit is 10,000mg per pound of body weight.)
The EPA indicates that propylene glycol is a non-irritant for eyes and skin.
Under the heading "General Toxicity Observations," the EPA states that "Upon reviewing the available toxicity information, the Agency has concluded that there are no endpoints of concern for oral, dermal, or inhalation exposure"
Under the heading "Carcinogenicity Classification," the EPA states that propylene glycol is "negative for carcinogenicity"
Under the heading "Mutagenicity Potential," which refers to its ability to induce genetic mutations, the EPA states that propylene glycol is "found to be negative" in tests for mutagenic or genotoxic potential.
Under the heading "FQPA Safety Factor," which adjusts toxicity estimates by a "10-fold safety factor (10X), to protect for special sensitivity in infants and children" when there is incomplete data: "The FQPA Safety Factor has been removed (i.e., reduced to IX) for propylene glycol... because there is no pre- or post-natal evidence for increased susceptibility following exposure. Further, the Agency has concluded that there are no endpoints of concern for oral, dermal, or inhalation exposure to propylene glycol... based on the low toxicity observed in studies conducted near or above testing limit doses"
The EPA's 2006 review of propylene glycol states 5 different times that "there are no endpoints for concern for oral, dermal, or inhalation exposure to propylene glycol."
The EPA states that propylene glycol is approved by the FDA for use in alcoholic beverages, confections and frostings, frozen dairy products, seasonings and flavorings, nuts and nut products, and all other food categories.
So, some people may be allergic to it. Shoot, I'm allergic to animal dander. But propylene glycol will not make you sick.
I keep hearing people say, "It's better just to breath oxygen." This may sound good as a common-sense assertion, but it does not bear scrutiny. The Earth's atmosphere is about 78% nitrogen and only about 20% oxygen (with 1% argon and 0.03% carbon dioxide). If breathing slightly less oxygen were bad for you, then living at a higher elevation would be hazardous to your health and minor variations in elevation above sea-level would impact your health.
Anyone who argues against the safety of propylene glycol based on its use in antifreeze is either ignorant or arguing in bad faith. To say that propylene glycol is an effective component in antifreeze is simply to say that it is highly water soluble. Dissolving anything in water lowers its freezing point (salt-water freezes at a lower temperature because it's salt dissolved into water). The the more of a substance that you can dissolve in water, the lower the freezing point of the resulting water-based solution. Since you can dissolve a heck of a lot of propylene glycol in water, it is highly effective in antifreeze.
Furthermore, the argument that propylene glycol is unsafe because it is an ingredient in antifreeze runs afoul of the fallacy of division, which mistakenly takes the properties of the whole to be properties of its components; e.g., an egg is white; and egg has a yolk; therefore a yolk is white. From the fact that some antifreeze is toxic, it does not follow that any single ingredient is toxic. Some glass cleaners contain vinegar. That doesn't make vinegar toxic.
Incidentally, the EPA has registered propylene glycol as an antimociobial for the following microbes: "Odor-causing bacteria, Fleas, Mites, Red lice, Animal pathogenic bacteria (G- and G+ vegetative), Shigella bacteria, Pasteurella bacteria, Listeria bacteria, Herpes Simplex I and II, Animal viruses, Influenza Virus A2, Aspergillus Niger Fungus, Mold/Mildew, Pseudomonas SPP., Shigella Flexneri, Shigella Sonnei." Sounds better than a flu shot.
The full text is available here: http://www.epa.gov/oppsrrd1/REDs/propylene_glycol_red.pdf
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