Propylene glycol toxicity

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Vocalek

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Toxicology. 2010 Jan 15. [Epub ahead of print]
Toxicological considerations on the use of propylene glycol as a humectant in cigarettes.

Gaworski CL, Oldham MJ, Coggins CR.
Altria Client Services, 601 East Jackson Street, Richmond, VA 23261, USA.
Propylene glycol (PG) is a humectant commonly used in cigarettes. Previous toxicological examinations of the effects on the addition of PG to tobacco used mixtures with several other flavoring agents. In the present work, toxicological comparisons were made of experimental cigarettes containing no added PG against otherwise similar cigarettes with three different amounts of PG added to the tobacco. The main toxicological comparison was a sub-chronic inhalation study with mainstream smoke in Sprague-Dawley rats (exposures of 150mg/m(3) of total particulate matter, 6h exposure per day, for 90 consecutive days). The target PG concentrations in the tobacco of the four cigarette types were 0, 4, 7 and 10%. Additional studies with mainstream smoke were bacterial mutagenicity (5 Salmonella strains, both with and without metabolic activation, particulate phase only), cytotoxicity of both particulate and gas/vapor phases (using the neutral red uptake assay), and analytical chemistry (41 analytes). The graded inclusion of PG into experimental cigarettes resulted in increases in the smoke concentrations of propylene oxide, at very low concentrations. Broadly similar responses were seen across the four cigarette types, and the responses were similar to those previously described in the scientific literature. The addition of PG to experimental cigarettes reduced concentrations of some smoke components (e.g. nicotine), but had minimal effects on the biological responses. Most of the changes produced in the 90-days of exposure were resolved in a 42-day post-inhalation period. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.
 

Vocalek

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I think that the key take-away message was that adding PG to cigarettes as a humectant "had minimal effects on the biological responses." In other words, it did not appear to be harmful.

I thought it interesting, though, that adding PG reduced concentrations of nicotine. Poor rats probably had to smoke more ciggies to get enough nic.
 
@Vocalek : Very helpful post.I believed from the day I heard and knew of e-cigs;its an alternative addiction.Like people sniff glue,nail polish remover and hundreds of other stuffs,its like that.e-cig helped me to stop analog cigs- the more dangerous one,I am happy for the fact.I had a WRONG impression,that the companies add something to e-liquid;so,I prepared e-liq in my lab (PG based).I concluded that PG vapor itself has the ability to make one addicted.I had to test it.It would sound inhuman,but I exposed 2 rabbits to PG vapor (5 minx4 times a dayx 4 days)-two after major meals,two before their defecation.On the 5th day,I stopped it.They were aggressive,a bit constipated too.The control rabbit (one) was exposed to water vapour.
The rabbits are in good health now,dont worry :)
I have no intension to make this report forwarded to any organization,for several reasons.
It is evident to me,I have to quit e-cig too for the benefit of not only my family,but for all who will be benefited by me,directly or indirectly.
Hope it helps some one.
By the way,PG vapor has a bronchodilator action too,(like albuterol (aka Salbutamol))-but the mechanism of action is different),so,asthmatics may find a "relief"-this is from my personal experience-I have asthma.But,I made a peripheral blood film of me,examined under microscope-I have noted the reduced Eosinophil count,reduced reticulocyte count,shift to left of neutrophil-an effect that is produced by high dose prolonged steroid use.
I need more opinion from the super specialists...
 

Katmar

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Sep 19, 2009
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I think that the key take-away message was that adding PG to cigarettes as a humectant "had minimal effects on the biological responses." In other words, it did not appear to be harmful.

I thought it interesting, though, that adding PG reduced concentrations of nicotine. Poor rats probably had to smoke more ciggies to get enough nic.

ROFL...............poor babies, how did they light them without opposible thumbs????
 

defunkt

Full Member
Sep 4, 2009
39
1
@Vocalek : Very helpful post.I believed from the day I heard and knew of e-cigs;its an alternative addiction.Like people sniff glue,nail polish remover and hundreds of other stuffs,its like that.e-cig helped me to stop analog cigs- the more dangerous one,I am happy for the fact.I had a WRONG impression,that the companies add something to e-liquid;so,I prepared e-liq in my lab (PG based).I concluded that PG vapor itself has the ability to make one addicted.I had to test it.It would sound inhuman,but I exposed 2 rabbits to PG vapor (5 minx4 times a dayx 4 days)-two after major meals,two before their defecation.On the 5th day,I stopped it.They were aggressive,a bit constipated too.The control rabbit (one) was exposed to water vapour.
The rabbits are in good health now,dont worry :)
I have no intension to make this report forwarded to any organization,for several reasons.
It is evident to me,I have to quit e-cig too for the benefit of not only my family,but for all who will be benefited by me,directly or indirectly.
Hope it helps some one.
By the way,PG vapor has a bronchodilator action too,(like albuterol (aka Salbutamol))-but the mechanism of action is different),so,asthmatics may find a "relief"-this is from my personal experience-I have asthma.But,I made a peripheral blood film of me,examined under microscope-I have noted the reduced Eosinophil count,reduced reticulocyte count,shift to left of neutrophil-an effect that is produced by high dose prolonged steroid use.
I need more opinion from the super specialists...

Would you mind explaining what " Eosinophil count,reduced reticulocyte count,shift to left of neutrophil" are exactly? Thanks in advance.
 

dk2

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Jan 20, 2010
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cheers
@all : we have conquered the bad habit of smoking cig; and we have to quit e-cig too...its my message to all.

Why quit ecigs I enjoy the pleasures of vaping as much as I did smoking but now I can do it with minimal health risks to myself and bystanders, its calming and rythmic my own little spiritual sanctuary. I'm encouraging everyone to start vaping(that's over eighteen of course)!
 

V4Lis4me

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Dec 18, 2009
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Most of the changes produced in the 90-days of exposure were resolved in a 42-day post-inhalation period. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.



Mainly,
I believe it would be in our best interest to know what changes happened in the 90 day exposure.
Not if they resolved themselves in 42 days or not, as we all are in CONSTANT EXPOSURE.... at much higher concentrations!


Where can I find the whole study?
Because, quite honestly, the changes that were invoked in the 90 days are in the real interest of us.
 

voltaire

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Dec 4, 2009
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I exposed 2 rabbits to PG vapor (5 minx4 times a dayx 4 days)-two after major meals,two before their defecation.On the 5th day,I stopped it.They were aggressive,a bit constipated too.The control rabbit (one) was exposed to water vapour.

I'm just curious how you knew they were about to poop, and later, how you knew they were constipated? Never mind, maybe I don't want to know! :shock:
 

V4Lis4me

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Toxicologic evaluation of humectants added to ciga... [Inhal Toxicol. 2002] - PubMed result

this one paints a better picture.....

quoted from above link....
nhal Toxicol. 2002 Nov;14(11):1135-52.Toxicologic evaluation of humectants added to cigarette tobacco: 13-week smoke inhalation study of glycerin and propylene glycol in Fischer 344 rats.

Heck JD, Gaworski CL, Rajendran N, Morrissey RL.
Lorillard Tobacco Co., Greensboro, NC 27420-1688, USA. dheck@lortobco.com
Glycerin (CAS no. 56-81-5) and propylene glycol (CAS no. 57-55-6) are commonly used as humectant ingredients in manufactured cigarettes to control and maintain the moisture content of the cut tobacco filler. The potential of these added humectants to affect the toxicity of cigarette smoke was investigated in a subchronic nose-only smoke inhalation study in rats. Filtered test cigarettes were prepared from an American-style tobacco blend containing either glycerin added at 5.1% w/w tobacco, propylene glycol at 2.2% w/w tobacco, or combinations of these humectants totaling 2.3%, 3.9%, and 7.2% w/w tobacco. Other groups of animals were exposed similarly to the smoke of reference cigarettes without added humectants, or to filtered air (sham control). Smoke exposures were conducted for 1 h/day, 5 days/wk for 13 wk, at target smoke particulate concentrations of 350 mg/m(3). All smoke-exposed groups had equivalent increases in blood carboxyhemoglobin, serum nicotine, and serum cotinine relative to the air controls. Smoke-associated reductions in body weights and occasional increases in heart and lung weights were generally similar among the various exposure conditions at necropsy. Increases in serum alkaline phosphatase and decreases in serum glucose and cholesterol were observed among smoke-exposed females relative to air controls. However, no significant differences in these parameters were evident between the humectant-containing and reference cigarette smoke exposure groups. Assessments of respiration conducted after 3, 6, 9, and 12 wk of smoke exposure indicated an initial smoke-related but not humectant-related decrease in respiratory rate, tidal volume, and minute volume during the first 20 min of each smoke exposure. Respiratory-tract histopathology was consistent across sexes and smoke groups, comprising (1) diffuse and focal alveolar pigmented macrophages and chronic interstitial inflammation in the lung, (2) laryngeal epithelial hyperplasia, squamous metaplasia, and scab formation, and (3) epithelial hyperplasia in the anterior nose. Smoke-related histopathology resolved substantially during a 6-wk postexposure recovery period. Addition of the tested humectants to cigarettes, singly or in combination, had no meaningful effect on the site, occurrence, or severity of respiratory-tract changes or on the measured indices of pulmonary function. It was concluded that the addition of glycerin and propylene glycol to cigarettes does not significantly affect the biological activity of inhaled cigarette smoke in this rat model.


there we go!
 
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