Is Propylene Glycol Monomethyl Ether safe when breathed in?

Inhalation of propylene glycol monomethyl ether vapor or aerosol can cause irritation to the eyes, skin, and respiratory tract, leading to symptoms such as cough, sore throat, watering eyes, redness, and pain.

Why here

Propylene glycol monomethyl ether is a volatile organic compound commonly used as a solvent in various consumer products like paints, cleaners, and cosmetics, where inhalation exposure to its vapors or aerosols can occur during use.

What would have to be true

Human exposure studies have shown irritation to the eyes and throat at 150 ppm, and eye irritation, lacrimation, blinking, rhinorrhea, and headache at 250 ppm. Concentrations above 150 ppm are generally considered self-limiting due to these irritating effects.

Inhalation of high concentrations of propylene glycol monomethyl ether can lead to central nervous system depression, characterized by symptoms such as drowsiness, dizziness, headache, and incoordination.

Why here

As a volatile solvent present in consumer products, inhalation of propylene glycol monomethyl ether vapors is a relevant exposure route.

What would have to be true

Exposure to very high concentrations can cause central nervous system depression. Animal studies observed initial sedation at 3000 ppm. Human studies at 250-300 ppm produced headaches, but did not impair motor coordination or neurological performance.

Chronic or high-level inhalation exposure to propylene glycol monomethyl ether has been associated with increased liver weights and altered hepatocytes in animal studies.

Why here

Inhalation is a primary exposure route for solvents like propylene glycol monomethyl ether found in consumer products.

What would have to be true

Chronic (2-year) daily inhalation exposures of rats and mice to 3000 ppm propylene glycol monomethyl ether produced signs of liver toxicity. The no observed adverse effect level (NOAEL) for chronic inhalation was 1000 ppm for female rats and male and female mice, with only dark foci in the liver of male rats at 1000 ppm.

While the primary alpha-isomer of propylene glycol monomethyl ether is generally considered to have a low potential for developmental toxicity, concerns have been suggested regarding potential human developmental toxicity due to the beta-isomer (an impurity typically less than 0.5% in commercial products), which can be metabolized to 2-methoxypropionic acid (2-MPA), a compound structurally similar to the teratogen methoxyacetic acid (MAA).

Why here

Inhalation exposure to products containing propylene glycol monomethyl ether, even with small amounts of the beta-isomer impurity, is a relevant route for potential metabolic conversion.

What would have to be true

Commercial propylene glycol monomethyl ether typically contains less than 0.5% of the beta-isomer. Urinary levels of 2-MPA were detected after human inhalation exposure to PGME-alpha vapor at concentrations of 15, 50, and 95 ppm.

The other side

The U.S. EPA has concluded that the toxicity database for propylene glycol monomethyl ether is complete and adequately protects the safety of infants and children, finding no need for a developmental neurotoxicity study or additional uncertainty factors. Additionally, some assessments classify it as not toxic to reproduction or development.

Inhalation exposure to propylene glycol monomethyl ether has been linked in human and in vitro studies to a decrease in capillary blood oxygenation and functional alveolar membrane changes.

Why here

Propylene glycol ethers are volatile organic compounds commonly used as solvents in occupational and household products, making inhalation exposure ubiquitous.

What would have to be true

Human participants exposed to 35 ppm propylene glycol monomethyl ether for four hours showed a decrease in capillary blood oxygenation. In vitro studies revealed functional alveolar membrane changes at low concentrations.

Propylene glycol monomethyl ether (PGME) is classified as A4, meaning it is not classifiable as a human carcinogen, based on studies that found no toxicologically relevant statistically significant increases in neoplasia in either rats or mice.

Why here

This classification is relevant for assessing the long-term health effects of indoor air exposure.

What would have to be true

General indoor air exposure.

Inhalation of propylene glycol monomethyl ether (PGME) vapor in high concentrations can cause irritation to the eyes, skin, and respiratory tract.

Why here

PGME is a volatile organic compound (VOC) found in various consumer products like paints and cleaning agents, which can be emitted into indoor air.

What would have to be true

High concentrations of PGME vapor in indoor air.

Exposure to very high concentrations of propylene glycol monomethyl ether (PGME) vapor can cause central nervous system depression, leading to symptoms such as drowsiness, headache, dizziness, and incoordination.

Why here

PGME is a volatile organic compound (VOC) that can be released into indoor air from products like paints and cleaning supplies.

What would have to be true

Very high concentrations of PGME vapor in indoor air.

Propylene glycol and glycol ethers (PGEs), including PGME, in indoor air have been associated with an increased likelihood of asthma, rhinitis, eczema, and IgE-sensitization in children.

Why here

PGME is a component of PGEs found in indoor air, originating from sources such as water-based paints and cleaning products.

What would have to be true

Children living in homes with higher levels of summed PGEs in indoor air (e.g., within the top 25% of measured concentrations).

The other side

The assessment of human health risk from PGEs is challenged by the correlated nature of VOC compounds from multiple indoor sources and the poorly understood role of other indoor environmental conditions (e.g., humidity, ventilation, temperature) on their emission and retention.

Long-term inhalation exposure to high levels of propylene glycol monomethyl ether (PGME) vapor in laboratory animals has been associated with increased liver weight and effects on the kidneys, including elevated deposition of alpha2u-globulin and associated nephropathy in male rats.

Why here

PGME is a volatile organic compound (VOC) that can be inhaled from indoor air over prolonged periods.

What would have to be true

High levels of PGME vapor (e.g., 300, 1000, or 3000 ppm in animal studies) over subchronic to chronic durations.

The other side

The kidney effects observed in male rats (alpha2u-globulin nephropathy) are considered a male rat-specific effect, indicating a lack of relevance for human risk assessment.