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Aerospace Medicine and Human Performance May 2022The previous Spacecraft Maximal Allowable Concentrations (SMACs) for propylene glycol were established based on a study of rodents exposed to propylene glycol (PG)...
The previous Spacecraft Maximal Allowable Concentrations (SMACs) for propylene glycol were established based on a study of rodents exposed to propylene glycol (PG) aerosol for 6 h/d, 5 d/wk for 90 d. This study has been used as the basis for the few existing limits, but all exposure concentrations were well above the saturated vapor concentration of ∼100 ppm for pure propylene glycol at room temperature. For this reason, the Environmental Protection Agency and the Agency for Toxic Substances and Disease Registry noted that the method used to generate the aerosols for the two published studies of animal exposures are not relevant to exposure conditions for the general public, and most regulatory agencies have not established inhalation limits for propylene glycol, citing lack of data. Since publication of the PG SMACs in 2008, an acute inhalation study was conducted in healthy human subjects which allows us to revise our assessment. This manuscript provides the rationale for increasing the prior limits for PG in spacecraft air from 32 and 17 ppm to 64 and 32 ppm for off-nominal scenarios/releases (1-h and 24-h limits) and from 9, 3, and 1.5 ppm to 32 ppm for all nominal timeframes (7, 30, and 180 d). Due to a lack of longer-term exposure data, NASA has elected to eliminate the 1000-d SMAC limit at this time.
Topics: Animals; Humans; Maximum Allowable Concentration; Propylene Glycol; Spacecraft; United States
PubMed: 35551723
DOI: 10.3357/AMHP.6037.2022 -
Current Drug Delivery 2024Nicotine is a fat-soluble substance that is easily absorbed through the skin and mucosal tissues of the human body. However, its properties, such as light exposure, heat...
BACKGROUND
Nicotine is a fat-soluble substance that is easily absorbed through the skin and mucosal tissues of the human body. However, its properties, such as light exposure, heat decomposition, and volatilization, restrict its development and application in external preparations.
OBJECTIVE
This study focused on the preparation of stable nicotine-encapsulated ethosomes.
METHODS
During their preparation, two water-phase miscible osmotic promoters, ethanol and propylene glycol (PG), were added to obtain a stable transdermal delivery system. Skin nicotine delivery was enhanced through the synergistic action of osmotic promoters and phosphatidylcholine in binary ethosomes. Various characteristics of the binary ethosomes were measured, including the vesicle size, particle size distribution, and zeta potential. In order to optimize the ratio of ethanol and PG, the skin permeability test was performed on mice in vitro in a Franz diffusion cell to compare cumulative skin permeabilities. The penetration depth and fluorescence intensity of rhodamine-B-entrapped vesicles in isolated mouse skin samples were observed using laser confocal scanning microscopy.
RESULTS
When ethanol:PG was used in a ratio of 5:5 (w/w), binary ethosomes were found to be the most stable, had the highest encapsulation rate (86.13 ± 1.40), smallest particle size (106.0 ± 11.0) nm, maximum transdermal depth (180 μm), and maximum fluorescence intensity (160 AU). Nicotineencapsulated ethosomes (ethanol: PG = 5:5, w/w) were an efficient and stable transdermal delivery system.
CONCLUSION
The nicotine-encapsulated ethosomes containing ethanol and PG are considered to be safe and reliable as a transdermal administration agent, which does not irritate the skin.
Topics: Mice; Humans; Animals; Liposomes; Skin Absorption; Nicotine; Ethanol; Skin; Administration, Cutaneous; Propylene Glycol
PubMed: 37132146
DOI: 10.2174/1567201820666230428122845 -
Cardiovascular Research Oct 2023Electronic cigarette use has grown exponentially in recent years, and while their popularity has increased, the long-term effects on the heart are yet to be fully... (Review)
Review
Electronic cigarette use has grown exponentially in recent years, and while their popularity has increased, the long-term effects on the heart are yet to be fully studied and understood. Originally designed as devices to assist with those trying to quit traditional combustible cigarette use, their popularity has attracted use by teens and adolescents who traditionally have not smoked combustible cigarettes. Acute effects on the heart have been shown to be similar to traditional combustible cigarettes, including increased heart rate and blood pressure. The main components of electronic cigarettes that contribute to these arrhythmic effects are found in the e-liquid that is aerosolized and inhaled, comprised of nicotine, flavourings, and a combination of vegetable glycerin (VG) and propylene glycol (PG). Nicotine can potentially induce both ventricular and atrial arrhythmogenesis, with both the atrial and ventricular effects resulting from the interactions of nicotine and the catecholamines they release via potassium channels. Atrial arrhythmogenesis, more specifically atrial fibrillation, can also occur due to structural alterations, which happens because of nicotine downregulating microRNAs 133 and 590, both post-transcriptional growth factor repressors. Liquid flavourings and the combination of PG and VG can possibly lead to arrhythmic events by exposing users to acrolein, an aldehyde that stimulates TRPA1 that in turn causes a change towards sympathetic activation and autonomic imbalance. The design of these electronic delivery devices is constantly changing; therefore, it has proven extremely difficult to study the long-term effects on the heart caused by electronic cigarettes but will be important to understand given their rising popularity. The arrhythmic effects of electronic cigarettes appear similar to traditional cigarettes as well; however, a comprehensive review has not been compiled and is the focus of this article.
Topics: Adolescent; Humans; Nicotine; Electronic Nicotine Delivery Systems; Atrial Fibrillation; Propylene Glycol; Glycerol
PubMed: 37517059
DOI: 10.1093/cvr/cvad113 -
Veterinary Medicine and Science Sep 2023Grazing in arid and semi-arid regions faces pregnant ewes with feed restrictions and hence affects the offspring muscle fibre characteristics. Using feed additives that...
Restricted maternal nutrition and supplementation of propylene glycol, monensin sodium and rumen-protected choline chloride during late pregnancy does not affect muscle fibre characteristics of offspring.
BACKGROUND
Grazing in arid and semi-arid regions faces pregnant ewes with feed restrictions and hence affects the offspring muscle fibre characteristics. Using feed additives that enhance nutrient availability during foetal muscle development is expected to alter offspring skeletal muscle characteristics.
OBJECTIVES
This study evaluated the effect of maternal restricted nutrition and supplementation of propylene glycol, monensin sodium and rumen-protected choline chloride on lamb's muscle fibre characteristics.
METHODS
Forty-eight Ghezel ewes were randomly allocated to one of six diets (N = 8) during the last 6 weeks of gestation: ad libitum feed intake (AL); restricted feeding (RF); restricted feeding containing propylene glycol (PG); restricted feeding containing propylene glycol and monensin sodium (MS); restricted feeding containing propylene glycol and rumen-protected choline chloride (RPC); restricted feeding containing propylene glycol, monensin sodium and rumen-protected choline chloride (PMC). The muscle samples were obtained from the semitendinosus muscle of 2-week-old male lambs (n = 5/treatment) via biopsy and were stained and classified as fibre types I, IIA and IIB.
RESULTS
Pre-parturient maternal feed restriction and administration of propylene glycol, monensin sodium and rumen-protected choline chloride had no significant effect on fibre-type composition, fibre density of muscle, muscle cross-sectional area and volume density of fibres (p > 0.05).
CONCLUSIONS
Either maternal dietary restriction or supplementation of nutrient flux-involved additives during late pregnancy did not alter muscle fibre development and had no short-term effects on muscle properties of the resulting offspring as myogenesis occurs in early and mid-gestation, not late gestation. Therefore, maternal nutrition may not be a problematic issue in sheep production in arid and semi-arid areas.
Topics: Pregnancy; Animals; Sheep; Female; Male; Monensin; Choline; Rumen; Propylene Glycol; Muscle Fibers, Skeletal; Dietary Supplements
PubMed: 37556348
DOI: 10.1002/vms3.1239 -
Environmental Science and Pollution... Apr 2022Propylene glycol (PG) is widely used in the foods, pharmaceuticals, oil industry, animal feed, cosmetics and other industries. Because of the existence of a chiral...
Propylene glycol (PG) is widely used in the foods, pharmaceuticals, oil industry, animal feed, cosmetics and other industries. Because of the existence of a chiral carbon center, PG forms R (Rectus)- and S (Sinister)-enantiomers. Currently, the toxicity study of its R-, S-enantiomers is still very scarce. In this study, we have assessed the developmental toxicity and neurotoxicity of the R-, S-, and RS-PG enantiomers in zebrafish larvae. We found that exposure to R-, S-, and RS-PG enantiomers did not significantly affect the basic developmental endpoints of embryos or larvae (i.e., embryonic movement, hatching, mortality, malformation, heartbeat, body length), indicating that R-, S-, and RS-PG exposures did not exhibit the basic developmental toxicity in zebrafish larvae. The toxicity of three enantiomers was lower than that of ethanol, and there was no significant difference between them. However, R-, S-, and RS-PG exposures with high doses could significantly change the eye diameter and locomotor activity of larval zebrafish, indicating that R-, S-, and RS-PG enantiomers of high doses could potentially exhibit the neurotoxicity and ocular developmental toxicity in zebrafish larvae. Therefore, the potential neurotoxicity and ocular developmental toxicity of R-, S-, and RS-PG enantiomers for infants and toddlers should be considered.
Topics: Animals; Embryo, Nonmammalian; Humans; Larva; Neurotoxicity Syndromes; Propylene Glycol; Water Pollutants, Chemical; Zebrafish
PubMed: 35000155
DOI: 10.1007/s11356-021-17538-8 -
Zeitschrift Fur Geburtshilfe Und... Aug 2023Propolis has become one of the most preferred supplements due to its beneficial biological properties. Organic (water and vegetable oils) and chemical (ethyl alcohol,...
BACKGROUND
Propolis has become one of the most preferred supplements due to its beneficial biological properties. Organic (water and vegetable oils) and chemical (ethyl alcohol, propylene glycol, and glycerol) solvents are used for propolis extraction. However, the effects of these chemicals on health should be taken into account.
OBJECTIVES
In this study, the effects of propolis extracts on health were evaluated.
METHODS
32 pregnant Wistar albino rats and 64 neonatal/young adults were given three different extractions of propolis (propylene glycol, water, and olive oil). Histopathological analyses were performed on the liver and brain, and blood samples were taken from the hearts of rats.
RESULTS
Histopathological scoring showed that the intensity of pycnotic hepatocyte, sinusoidal dilatation, and bleeding was high in liver samples of pregnant and baby rats given propylene glycol extract of propolis (p<0.05). Propylene glycol extract caused dilatation of blood vessels and apoptosis of neurons in brain tissue. The histopathological score was significantly lower in liver and brain tissues of rats treated with water and olive oil extract compared to propylene propolis groups (p<0.05). Liver enzyme levels in the blood increased in propylene propolis rats (p<0.05).
CONCLUSION
Histopathological changes and biochemical alterations may indicate that propylene glycol extracts of propolis are more toxic than olive oil and water extracts. Therefore, olive oil and water extracts of propolis are more reliable than propylene glycol extract in pregnant and infant rats.
Topics: Humans; Rats; Animals; Pregnancy; Female; Propolis; Animals, Newborn; Rats, Wistar; Olive Oil; Liver; Propylene Glycol; Central Nervous System
PubMed: 36889342
DOI: 10.1055/a-2010-4009 -
Cryobiology Oct 2022Vitrification is a promising cryopreservation technique for complex specimens such as tissues and organs. However, it is challenging to identify mixtures of...
Vitrification is a promising cryopreservation technique for complex specimens such as tissues and organs. However, it is challenging to identify mixtures of cryoprotectants (CPAs) that prevent ice formation without exerting excessive toxicity. In this work, we developed a multi-CPA toxicity model that predicts the toxicity kinetics of mixtures containing five of the most common CPAs used in the field (glycerol, dimethyl sulfoxide (DMSO), propylene glycol, ethylene glycol, and formamide). The model accounts for specific toxicity, non-specific toxicity, and interactions between CPAs. The proposed model shows reasonable agreement with training data for single and binary CPA solutions, as well as ternary CPA solution validation data. Sloppy model analysis was used to examine the model parameters that were most important for predictions, providing clues about mechanisms of toxicity. This analysis revealed that the model terms for non-specific toxicity were particularly important, especially the non-specific toxicity of propylene glycol, as well as model terms for specific toxicity of formamide and interactions between formamide and glycerol. To demonstrate the potential for model-based design of vitrification methods, we paired the multi-CPA toxicity model with a published vitrification/devitrification model to identify vitrifiable CPA mixtures that are predicted to have minimal toxicity. The resulting optimized vitrification solution composition was a mixture of 7.4 molal glycerol, 1.4 molal DMSO, and 2.4 molal formamide. This demonstrates the potential for mathematical optimization of vitrification solution composition and sets the stage for future studies to optimize the complete vitrification process, including CPA mixture composition and CPA addition and removal methods.
Topics: Cryopreservation; Cryoprotective Agents; Dimethyl Sulfoxide; Ethylene Glycol; Formamides; Glycerol; Ice; Propylene Glycol; Vitrification
PubMed: 36113568
DOI: 10.1016/j.cryobiol.2022.09.002 -
Current Opinion in Microbiology Oct 2021Catabolic bacterial microcompartments (BMC), or metabolosomes, are self-assembling structures formed by enzymes enclosed by porous protein shells. They provide a... (Review)
Review
Catabolic bacterial microcompartments (BMC), or metabolosomes, are self-assembling structures formed by enzymes enclosed by porous protein shells. They provide a specialised environment inside bacterial cells separating a short catabolic pathway with reactive or toxic intermediates from the cytoplasm. Substrates for microcompartment metabolism like ethanolamine and 1,2-propanediol are constantly produced in the human intestine by bacterial metabolism of food or host cell components. Enteric pathogens gain a competitive advantage in the intestine by metabolising these substrates, an advantage enhanced by the host inflammatory response. They exploit the intestinal specificity of signature metabolosome substrates by adopting substrate sensors and regulators encoded by BMC operons for governance of non-metabolic processes in pathogenesis. In turn, products of microcompartment metabolism regulate the host immune system.
Topics: Bacteria; Bacterial Proteins; Ethanolamine; Humans; Propylene Glycol; Virulence
PubMed: 34107380
DOI: 10.1016/j.mib.2021.05.009 -
Dermatitis : Contact, Atopic,...Aerosolized liquid (e-liquid) of electronic cigarettes can be toxic. Beyond the solvent (propylene glycol, vegetable glycerin) and nicotine, little is known about the...
BACKGROUND
Aerosolized liquid (e-liquid) of electronic cigarettes can be toxic. Beyond the solvent (propylene glycol, vegetable glycerin) and nicotine, little is known about the liquid composition. Formaldehyde, a carcinogen and source of contact dermatitis, has been reported in the vaporized e-liquid, but no studies have assessed the actual e-liquid.
OBJECTIVE
The aim of the study was to evaluate e-liquid products for the presence of formaldehyde.
METHODS
Sixteen e-liquid products were purchased and analyzed for the release of formaldehyde using the chromotropic acid method of detection.
RESULTS
Of the 16 e-liquids purchased, 4 (25%) were positive for the presence of formaldehyde; 2 were flavored and 2 were nonflavored. All positive e-liquids were in pods or disposable electronic cigarette devices, and 2 were purchased from local vape shops. The average nicotine content in the positive e-liquids was 3.85% versus 4.03% in the negative e-liquids.
CONCLUSIONS
The e-liquid products contain toxic chemicals not declared on product labels, as shown in this study with 25.0% of e-liquids containing formaldehyde. All positive e-liquids were within pods or disposable devices. Continued analysis of e-liquids and increased product regulation are needed.
Topics: Carcinogens; Electronic Nicotine Delivery Systems; Formaldehyde; Glycerol; Humans; Nicotine; Propylene Glycol; Solvents
PubMed: 34115663
DOI: 10.1097/DER.0000000000000771 -
Dermatitis : Contact, Atopic,...Both active and inactive ingredients in topical ophthalmic agents may cause allergic contact dermatitis. Here, we examined ingredients in prescription topical ophthalmic...
BACKGROUND/OBJECTIVE
Both active and inactive ingredients in topical ophthalmic agents may cause allergic contact dermatitis. Here, we examined ingredients in prescription topical ophthalmic medications available in the United States.
METHODS
A comprehensive list of topical ophthalmic medications was generated using AccessPharmacy. Categories included antiglaucoma, antibiotic, antibiotic/corticosteroid, corticosteroid, antiviral, antifungal, mydriatic, and miotic agents. For each formulation, ingredients were investigated using the National Institutes of Health US National Library of Medicine database and/or manufacturer websites. Counts and proportions were calculated for inactive ingredients, including those in the American Contact Dermatitis Society (ACDS) Core 90 Allergen Series.
RESULTS
Two hundred sixty-four unique prescription ophthalmic medications met the inclusion criteria. The most common ACDS Core 90 allergen/cross-reactor inactive ingredient was benzalkonium chloride (68.1%, 180/264), followed by sorbates (11.7%, 31/264), parabens (6.8%, 18/264), sodium metabisulfite (3.8%, 10/264), propylene glycol (3.0%, 8/264), and lanolin (3.0%, 8/264). Approximately 21% (20.8%, 55/264) of products had no ACDS Core 90 allergens/cross-reactor inactive ingredients. The most common ACDS Core 90 allergen/cross-reactor active ingredients were aminoglycoside antibiotics, bacitracin/polymyxin B, and corticosteroids. Important non-ACDS Core 90 allergens included inactive ingredients, such as EDTA 28.0% and thimerosal 2.7%, as well as active ingredients, especially β-blockers.
CONCLUSIONS
Benzalkonium chloride, sodium metabisulfite, propylene glycol, and lanolin were common inactive ingredient allergens. Most ophthalmic categories had low allergen formulations available for patients with contact allergy.
Topics: Allergens; Dermatitis, Allergic Contact; Drug Hypersensitivity; Humans; Lanolin; Ophthalmology; Patch Tests; Prescriptions; Propylene Glycol; Sulfites; United States
PubMed: 34115664
DOI: 10.1097/DER.0000000000000751