I had been under the impression that no real long-term studies had been done on the effects of inhaling vaporized PG. I had seen reference on ECF to a study on the effects of PG/VG added to tobacco (no adverse effects), but given that the rats were still inhaling tobacco smoke, it didn't really seem applicable to our situation as vapers.
But I just did a little quick research through the Web of Science database and discovered some articles I have not yet seen referenced on ECF or anywhere in the media for that matter (my apologies if they have been and I missed it) The following is the reference followed by a short description. Due to copy write laws, I do not believe I can "publish" the articles on this forum, but if you PM me, there is no rule against me emailing them to you for academic purposes.
TESTS FOR THE CHRONIC TOXICITY OF PROPYLEXE GLYCOL
AND TRIETHYLENE GLYCOL ON MONKEYS AND RATS BY
VAPOR INHALATION AND ORAL ADMINISTRATION
JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS Volume: 91 Issue: 1 Pages: 52-76 Published: 1947
Ah the good old days when you could order 45 monkeys from Columbia, pump them full of whatever chemicals you want, and kill them for autopsy study without any animal rights activists getting all up on your junk.
Long story short, the scientists exposed groups of rats and Macacus Rhesus monkeys to concentrated PG vapor for 12-18 months. The rats showed no differences between PG and control groups in organ function. There was evidence of minor irritation in the upper lungs of the rats (not harmful however), but I think that is to be expected given the concentrations they were exposed to.
The monkey (who are erect mammals, and so have the same risk as humans to potential buildup in the lungs) results were similar. No difference in organ function, and no sign of irritation either. The monkeys were also riddled with nematodes, but that came from Columbia and were present in both PG and control. Actually in both the rat and monkey trials, the PG groups experienced better health and greater weight gain.
AEROSOL PENICILLIN
Blood Levels of Penicillin Obtained by Inhalation of Aerosols Produced
by a Combined Steam Generator and Aerosolizer, with
the Use of Propylene Glycol, Tents and a Breathing Box
JAMA-JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION Volume: 134 Issue: 11 Pages: 932-938 Published: 1947
Scientists tested the possibility of delivering antibiotics to the body through aerosolized vapors of PG and water. PG was chosen due to penicillin's solubility in the substance. Not only was it effective in delivering the antibiotic, but the control group (just vapor, no antibiotic) also showed reduced bacterial levels. This is due to PGs germicidal properties. It was examined as a way to sterilize urban areas after a fire to reduce disease spread, and is described in this time article, however I cannot locate the original paper.
Sputum Cytology After Inhalation of Heated
Propylene Glycol
JAMA-JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION Volume: 178 Issue: 6 Pages: 668-& Published: 1961
For those who don't know, sputum is the result of hucking a lugie. Phlem, mucus, respiratory snot, etc. Its cellular components can also be examined to detect lung cancer. But you have to cough it up. This can be difficult for those with chronic bronchitis, so these scientists had people inhale a warm PG vapor. It was soothing to the patients, and also resulted in people coughing a whole lot of crap up, particularly smokers (sound familiar?
) It even saved one guy's life! according to the paper:
"One patient with severe acute bronchitis and
asthma experienced prompt relief of a collapsed
right middle lobe, which was presumably a secondary
condition resulting from a mucus plug,
after a fortuitous propylene glycol inhalation."
Subchronic nose-only inhalation study of propylene glycol in Sprague-Dawley rats.
Food Chem Toxicol. 1989 Sep;27(9):573-83.
I couldn't get online access to this paper, and I'm currently too lazy to drag my ... over to UMass Amherst and pay $1/hr for parking. But I found the abstract. The rats were made to breathe PG vapor. Same as the earlier paper, no differences in PG and control groups except that high-concentration PG rats experienced nosebleeds and dry eyes. (I haven't gotten nosebleeds, but will sometimes get dry eyes. ClearEyes and a netty pot should do the trick.)
So that's what I found. Funny the FDA hasn't looked back and found these 1940's papers. I'm thinking of writing up a more professional editorial based on these studies and sending it to newspapers until someone decides to publish. Again, PM me with your email if you want a copy of the papers yourself, I know not everyone is lucky enough to have university access to a database that costs hundreds of thousands of dollars per year.
But I just did a little quick research through the Web of Science database and discovered some articles I have not yet seen referenced on ECF or anywhere in the media for that matter (my apologies if they have been and I missed it) The following is the reference followed by a short description. Due to copy write laws, I do not believe I can "publish" the articles on this forum, but if you PM me, there is no rule against me emailing them to you for academic purposes.
TESTS FOR THE CHRONIC TOXICITY OF PROPYLEXE GLYCOL
AND TRIETHYLENE GLYCOL ON MONKEYS AND RATS BY
VAPOR INHALATION AND ORAL ADMINISTRATION
JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS Volume: 91 Issue: 1 Pages: 52-76 Published: 1947
Ah the good old days when you could order 45 monkeys from Columbia, pump them full of whatever chemicals you want, and kill them for autopsy study without any animal rights activists getting all up on your junk.
Long story short, the scientists exposed groups of rats and Macacus Rhesus monkeys to concentrated PG vapor for 12-18 months. The rats showed no differences between PG and control groups in organ function. There was evidence of minor irritation in the upper lungs of the rats (not harmful however), but I think that is to be expected given the concentrations they were exposed to.
The monkey (who are erect mammals, and so have the same risk as humans to potential buildup in the lungs) results were similar. No difference in organ function, and no sign of irritation either. The monkeys were also riddled with nematodes, but that came from Columbia and were present in both PG and control. Actually in both the rat and monkey trials, the PG groups experienced better health and greater weight gain.
AEROSOL PENICILLIN
Blood Levels of Penicillin Obtained by Inhalation of Aerosols Produced
by a Combined Steam Generator and Aerosolizer, with
the Use of Propylene Glycol, Tents and a Breathing Box
JAMA-JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION Volume: 134 Issue: 11 Pages: 932-938 Published: 1947
Scientists tested the possibility of delivering antibiotics to the body through aerosolized vapors of PG and water. PG was chosen due to penicillin's solubility in the substance. Not only was it effective in delivering the antibiotic, but the control group (just vapor, no antibiotic) also showed reduced bacterial levels. This is due to PGs germicidal properties. It was examined as a way to sterilize urban areas after a fire to reduce disease spread, and is described in this time article, however I cannot locate the original paper.
Sputum Cytology After Inhalation of Heated
Propylene Glycol
JAMA-JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION Volume: 178 Issue: 6 Pages: 668-& Published: 1961
For those who don't know, sputum is the result of hucking a lugie. Phlem, mucus, respiratory snot, etc. Its cellular components can also be examined to detect lung cancer. But you have to cough it up. This can be difficult for those with chronic bronchitis, so these scientists had people inhale a warm PG vapor. It was soothing to the patients, and also resulted in people coughing a whole lot of crap up, particularly smokers (sound familiar?
) It even saved one guy's life! according to the paper: "One patient with severe acute bronchitis and
asthma experienced prompt relief of a collapsed
right middle lobe, which was presumably a secondary
condition resulting from a mucus plug,
after a fortuitous propylene glycol inhalation."
Subchronic nose-only inhalation study of propylene glycol in Sprague-Dawley rats.
Food Chem Toxicol. 1989 Sep;27(9):573-83.
I couldn't get online access to this paper, and I'm currently too lazy to drag my ... over to UMass Amherst and pay $1/hr for parking. But I found the abstract. The rats were made to breathe PG vapor. Same as the earlier paper, no differences in PG and control groups except that high-concentration PG rats experienced nosebleeds and dry eyes. (I haven't gotten nosebleeds, but will sometimes get dry eyes. ClearEyes and a netty pot should do the trick.)
So that's what I found. Funny the FDA hasn't looked back and found these 1940's papers. I'm thinking of writing up a more professional editorial based on these studies and sending it to newspapers until someone decides to publish. Again, PM me with your email if you want a copy of the papers yourself, I know not everyone is lucky enough to have university access to a database that costs hundreds of thousands of dollars per year.
