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CHEMINFO Record Number: 788
CCOHS Chemical Name: Polyalkylene glycol monobutyl ether, molecular weight 4000

EO/PO co-polymer (non-specific name)
Polyalkylene glycol monobutyl ether (non-specific name)
Ethylene oxide/propylene oxide co-polymer (non-specific name)
Oxirane, methyl-, polymer with oxirane, monobutyl ether, molecular weight 4000
Oxirane, methyl-, polymer with oxirane, monobutyl ether (non- specific name)
Poly(ethylene oxide-propylene oxide) butyl ether

Trade Name(s):
UCON 50-HB-5100
UCON Lubricant 50-HB-5100
Poly G WS

CAS Registry Number: 9038-95-3
RTECS Number(s): YP8460000
Chemical Family: Aliphatic ether alcohol / aliphatic glycol ether / polyalkylene glycol monoether
Molecular Formula: Complex polymer
Structural Formula: CH3-(CH2)3-(OCH2CH2)x[OCH2CH(CH3)]yOH


Appearance and Odour:
Essentially colourless liquid.(10)

Odour Threshold:
Information not available.

Warning Properties:
Information not available for evaluation.

Polyalkylene glycol monobutyl ether (PAGMBE) compounds are butyl alcohol started, random linear co-polymers of ethylene oxide and propylene oxide. They contain equal amounts by weight of oxyethylene and oxypropylene groups. These compounds are available in a range of molecular weights from 270 to approximately 4000, and have viscosities from 55 to 5100 Saybolt Universal Seconds (SUS) (8.9 to 1104 centistokes) at 37.8 deg C (100 deg F).(11,12) All of the polyalkylene glycol monobutyl ethers have the same CAS Registry Number (11), but the toxicity increases with increasing molecular weight. Therefore, this CHEMINFO record specifically reviews the hazards and control measures for the polyalkylene glycol monobutyl ether (PAGMBE) with an average molecular weight of 4000 (mw 4000). The CHEMINFO database contains records for 8 other PAGMBE compounds with different molecular weights.

Uses and Occurrences:
PAGMBEs are mainly used as lubricants and fluids in a wide variety of industrial processes and applications. They are also used as chemical intermediates, ink and dye solvents, nonvolatile solvents, softeners and plasticizers, foam control agents; in cosmetic applications, skin creams and lotions, bath oils, antiperspirants, deodorants and other lotions and creams; and as demulsifiers.(11,12)


Essentially colourless liquid. No unusual hazard in a fire situation. Can burn if strongly heated. VERY TOXIC. Inhalation of aerosol may be fatal. Animal evidence suggests aerosol exposure can cause potentially fatal lung injury (pulmonary edema)--effects may be delayed.


Effects of Short-Term (Acute) Exposure

Polyalkylene glycol monobutyl ether with a molecular weight of 4000 (PAGMBE (mw 4000)) does not readily form a vapour at room temperature. Therefore, inhalation exposures are unlikely to occur unless the material is heated or misted. Animal studies indicate that short-term exposure to relatively low concentrations of mists can cause significant lung injury including potentially fatal fluid accumulation (pulmonary edema). Symptoms of pulmonary edema (e.g. shortness of breath and chest tightness) may be delayed for up to 48 hours. There is no human information available.

Skin Contact:
PAGMBE (mw 4000) is expected to cause no or mild irritation, based on animal information. There is no human information available.
An animal toxicity value suggests that PAGMBE (mw 4000) will not produce toxicity if absorbed through the skin.

Eye Contact:
PAGMBE (mw 4000) is not expected to be an eye irritant, based on an animal study. There is no human information available.

Animal toxicity information indicates that PAGMBE (mw 4000) is not toxic following ingestion. One animal study indicates that signs and symptoms of central nervous system (CNS) depression, such as lack of coordination, nausea, dizziness and vomiting, may develop following ingestion of very large amounts. There is no human information available. Ingestion is not a typical route of occupational exposure.

Effects of Long-Term (Chronic) Exposure

There is no human information available.

Lungs/Respiratory System:
Animal toxicity testing suggests that long-term inhalation exposure to low aerosol concentrations could cause lung irritation and injury.


No human information was located. One mouse study showed negative results following skin application of PAGMBE (mw 4000).

The International Agency for Research on Cancer (IARC) has not evaluated the carcinogenicity of this chemical.

The American Conference of Governmental Industrial Hygienists (ACGIH) has no listing for this chemical.

The US National Toxicology Program (NTP) has not listed this chemical in its report on carcinogens.

Teratogenicity and Embryotoxicity:
No human or animal information was located.

Reproductive Toxicity:
No human or animal information was located.

No information was located.

Toxicologically Synergistic Materials:
No information was located.

Potential for Accumulation:
No information was located.


If aerosol exposure occurs, remove source of contamination or move victim to fresh air. If breathing is difficult, trained personnel should administer emergency oxygen. DO NOT allow victim to move about unnecessarily. Symptoms of pulmonary edema can be delayed up to 48 hours after exposure. Quickly transport victim to an emergency care facility.

Skin Contact:
No health effects are expected. If irritation does occur, flush with lukewarm, gently flowing water for 5 minutes. If irritation persists, obtain medical advice.

Eye Contact:
No health effects are expected. Immediately flush the contaminated eye(s) with lukewarm, gently flowing water for 5 minutes, while holding the eyelid(s) open. Obtain medical advice.

If irritation or discomfort occur, obtain medical advice.

First Aid Comments:
Provide general supportive measures (comfort, warmth, rest).
Some first aid procedures recommended above require advanced first aid training. Protocols for undertaking advanced procedures must be developed in consultation with a doctor and must be routinely reviewed.
All first aid procedures should be periodically reviewed by a doctor familiar with the material and its conditions of use in the workplace.


Flash Point:
180 deg C (356 deg F) (Pensky-Martens closed cup) (12)

Lower Flammable (Explosive) Limit (LFL/LEL):
Not available

Upper Flammable (Explosive) Limit (UFL/UEL):
Not available

Autoignition (Ignition) Temperature:
Not available

Sensitivity to Mechanical Impact:
Not sensitive. Stable material.

Sensitivity to Static Charge:
No information is available on the electrical conductivity of polyalkylene glycol monobutyl ethers (PAGMBEs). PAGMBE vapours will not be ignited by a static discharge because of the high flash point.

Electrical Conductivity:
Not available

Combustion and Thermal Decomposition Products:
The main products of combustion are carbon monoxide, carbon dioxide. Incomplete combustion may also produce irritating smoke and toxic and/or irritating gases or fumes.

Fire Hazard Summary:
This material can burn if strongly heated. During a fire, irritating/toxic gases and fumes may be formed.

Extinguishing Media:
SMALL FIRES: Carbon dioxide or dry chemical powder. LARGE FIRES: Alcohol or all-purpose-type foam, water spray or fog. Foam manufacturers should be consulted for recommendations regarding types of foams and application rates.

Fire Fighting Instructions:
Evacuate area and fight fire from a safe distance or a protected location. Approach fire from upwind to avoid toxic vapours and potentially toxic decomposition products.
Water or foam may cause frothing. The frothing may be violent and could endanger personnel close to the fire. However, a water spray or fog that is carefully applied to the surface of the liquid, preferably with a fine spray or fog nozzle, will cause frothing that will blanket and extinguish the fire. DO NOT direct a solid stream of water or foam into hot, burning pools, since this may cause frothing and increase fire intensity. In addition, water can be used in the form of spray or fog to absorb heat, keep containers cool and protect fire-exposed material. Solid streams of water may be ineffective and spread material. If a leak or spill has not ignited, use water spray to disperse the vapours, dilute the spill to a nonflammable mixture and protect personnel attempting to stop a leak. Water spray may be used to flush spills away from ignition sources.

Protection of Fire Fighters:
Mists and vapours of this material are very hazardous to health. Firefighters may enter the area if positive pressure self-contained breathing apparatus (NIOSH approved or equivalent) and full Bunker Gear is worn.


NFPA - Comments:
NFPA has no listing for this chemical in Codes 49 or 325.


Molecular Weight: 3930 (average)

Conversion Factor:
Not applicable

Physical State: Liquid
Melting Point: Not applicable. See Other Physical Properties for POUR POINT.
Boiling Point: Not applicable; decomposes slightly at elevated temperatures.(12)
Relative Density (Specific Gravity): 1.063 at 20 deg C (11,12); 1.045 at 40 deg C (12) (water = 1)
Solubility in Water: Soluble in cold water (12)
Solubility in Other Liquids: Soluble in a wide variety of organic solvents, including acetone, methanol, isopropanol, other aliphatic alcohols, propylene glycol, butyl cellosolve, butyl ether and toluene; insoluble in saturated hydrocarbons, such as cyclohexane, heptane, kerosene, petroleum ether, and diethylene glycol and ethylene glycol.(12)
Coefficient of Oil/Water Distribution (Partition Coefficient): Not available
pH Value: Not available
Viscosity-Kinematic: 1104 mm2/s (1104 centistokes) at 38 deg C (100 deg F) (11)
Saybolt Universal Viscosity: 5100 Saybolt Universal seconds at 38 deg C (100 deg F) (11,12)
Surface Tension: 35-40 mN/m (35-40 dynes/cm) at 20 deg C (12)
Vapour Density: Not applicable
Vapour Pressure: Very low; less than 0.00013 kPa (0.001 mm Hg) at 20 deg C (12)
Saturation Vapour Concentration: Very low; less than 1.3 ppm (less than 0.00013%) (calculated)
Evaporation Rate: Essentially zero.
Henry's Law Constant: Not available

Other Physical Properties:
VISCOSITY INDEX: 281 (11,12)
POUR POINT: -29 deg C (-20 deg F) (11,12)


Normally stable. PAGMBEs decompose slightly at elevated temperatures to form low molecular weight products.(12)

Hazardous Polymerization:
Does not occur.

Incompatibility - Materials to Avoid:

NOTE: Chemical reactions that could result in a hazardous situation (e.g. generation of flammable or toxic chemicals, fire or detonation) are listed here. Many of these reactions can be done safely if specific control measures (e.g. cooling of the reaction) are in place. Although not intended to be complete, an overview of important reactions involving common chemicals is provided to assist in the development of safe work practices.

PAGMBEs are chemically stable.(12) Strong oxidants, like chlorine, hydrogen peroxide, permanganates or persulfates can cause degradation.(11) Strong acids (e.g. sulfuric acid) at high temperatures, strong bases (e.g. potassium or sodium hydroxide), and materials reactive with hydroxyl compounds (e.g. active metals such as sodium and magnesium) can react with PAGMBEs.

Hazardous Decomposition Products:
None reported

Conditions to Avoid:
Temperatures above 180 deg C.

Corrosivity to Metals:
PAGMBEs are not corrosive to iron, carbon steel, brass, bronze, and aluminum under normal operating conditions.(12)

Corrosivity to Non-Metals:
PAGMBE (mw 4000) does not attack elastomers, like Viton A, and other fluorocarbons, like Kalrez and Fluoraz, neoprene, ethylene-propylene-diene (EPDM), natural rubber, butyl rubber, silicone, and fluorosilicone. It can attack Buna N and S.(12) PAGMBEs soften and lift many industrial coatings, like alkyd and vinyl coatings.(12) Catalyzed epoxy, epoxy-phenolic and modified phenolic coatings are not attacked by PAGMBEs.(12)


LC50 (rat): 106 mg/m3 (4-hour aerosol exposure) (1)

LD50 (oral, rat): 48700 mg/kg (2)
LD50 (oral, male rabbit): 16800 mg/kg (cited as 15.8 mL/kg) (3)

LD50 (dermal, rabbit): greater than 21000 mg/kg (1/4 deaths) (1)

Eye Irritation:

Not irritating to the eyes.

Application of 0.1 mL of polyalkylene glycol monobutyl ether with a molecular weight of 4000 (PAGMBE (mw 4000)) produced no irritation in rabbits.(1)

Skin Irritation:

Not irritating to the skin.

Application of 0.5 mL of PAGMBE (mw 4000), under occlusive cover, for 4 hours, produced no irritation in rabbits.(1) Application of 500 mg of PAGMBE (mw 4000) produced mild irritation in rabbits.(4, unconfirmed)

Effects of Short-Term (Acute) Exposure:

Short-term exposure (less than 2 weeks) to relatively low aerosol concentrations of PAGMBE (mw 4000) has produced significant lung injury in animals.

LC50 testing with PAGMBE (mw 4000) aerosols in male rats, mice, guinea pigs, hamsters and dogs with exposures to 50, 100, 200 or 500 mg/m3 for 4 hours showed rats and mice to be more sensitive. Lung weights were increased in all rodent species, although only at 100 mg/m3 and higher for guinea pigs. During exposure, the animals did not show any treatment-related effects. Mortality was delayed between 3-9 days after exposure. Significant lung injury was noted in all animal that died and some survivors.(8) Male rats were exposed to 22 mg/m3 of PAGMBE (mw 4000) aerosols for 3 consecutive days. A substantial inflammatory response in the lungs, as well as fluid accumulation, was observed.(7) Male rats were exposed nose-only to 75 mg/m3 PAGMBE (mw 4000) aerosol (mass median aerodynamic diameter 1.08) for 2, 4 or 6 hours. Male rats were also exposed nose-only to 75 mg/m3 of two of another manufacturer's PAGMBE (mw 4000 and 4500) aerosol (mass median aerodynamic diameter 0.68 or 0.80) for 2 or 6 hours. In all cases, lung damage (pulmonary edema) and mortality was observed in the animals by day 4.(14) Rats were exposed to PAGMBE (mw 4000) aerosols at 0, 5, 26 or 50 mg/m3 for 2 weeks. Reductions in mean body weight gain were observed in high-exposure males and mid- and high-exposure females. Autopsy showed significant lung injury, even at the lowest concentration. Partial recovery occurred during a 2-week follow-up period.(1) There were similar findings in other 2-week studies.(5,6)

Exposure to high oral doses of PAGMBE (mw 4000) has produced signs of central nervous system (CNS) depression and deaths in mice, rats and rabbits.(3)

Effects of Long-Term (Chronic) Exposure:

Long-term inhalation exposure to low concentrations (1-5 mg/m3) PAGMBE (mw 4000) aerosols has produced severe, irreversible lung injury in rats.(6)

Rats were exposed to 0.3, 1 or 5 mg/m3 PAGMBE (mw 4000) aerosols for 13 weeks. Half of the animals were terminated at this point and half after a 5-week recovery period. There were no exposure- related clinical signs or deaths. Absolute lung weights were increased in males exposed to 1 mg/m3 and in both sexes exposed to 5 mg/m3. Irreversible lung injury was observed in all but 1/80 animals exposed to 1 or 5 mg/m3 and terminated at the end of exposure or after the recovery period. The incidence and severity of effects were dose-related.(6)

Rats (10/sex/group) were exposed to 0, 0.04, 0.2, 1.0 or 5.0% PAGMBE (mw 4000) in their diets for 90 days. Approximate doses were 0, 20, 100, 500 or 2500 mg/kg/day for females and 25, 120, 600 or 3000 mg/kg/day for males. No significant effects were observed for mortality, body weight gain, liver or kidney weight or food consumption. At 5%, detailed autopsy showed significant kidney and liver injury. Milder changes that were considered transitory were observed in animals exposed to 1% and no changes were noted at 0.2%.(13) No differences were observed in rats (20/sex/group) exposed to PAGMBE (mw 4000) in the diet at levels up to 500 mg/kg/day for 2 years. Negative results were also found with dogs exposed to up to 1670 mg/kg/day.(3,13)

Skin Sensitization:
Negative results were obtained in guinea pigs with a PAGMBE of unspecified molecular weight (Bel-Ray Syncom 1400; CAS 9038-95-3)).(9)

PAGMBE (mw 4000) was painted without dilution on the clipped skin of mice, 3 times/week until death. No papillomas or carcinomas developed.(3)


Selected Bibliography:
(1) Klonne, D.R., et al. Acute and 2-week inhalation toxicity studies on aerosols of selected ethylene oxide/propylene oxide polymers in rats. Fundamental and Applied Toxicology. Vol. 9, no. 4 (Nov. 1987). p. 773-784
(2) Mellon Institute of Industrial Research. Work in progress. Report 15-54. Union Carbide Corporation, June 30, 1952
(3) Smyth, H., Jr., et al. Oral toxicity and excretion of four commercial polyoxyalkylene glycol compounds. Toxicology and Applied Pharmacology. Vol. 16, no. 3 (May 1970). p. 675-680
(4) MDL Information Systems, Inc. Ucon 50-HB-5100. Last updated: 2000-09. In: Registry of Toxic Effects of Chemical Substances (RTECS(R)). [CD-ROM]. Canadian Centre for Occupational Health and Safety (CCOHS). Also available at: <> {Subscription required}
(5) Ulrich, C.E., et al. Two-week aerosol inhalation study in rats of ethylene oxide/propylene oxide copolymers. Drug and Chemical Toxicology. Vol. 15, no. 1 (Mar. 1992). p. 15-31
(6) Klonne, D.R., et al. Pulmonary fibrosis produced in F-344 rats by subchronic inhalation of aerosols of a 4000 molecular weight ethylene oxide/propylene oxide polymer. Fundamental and Applied Toxicology. Vol. 10, no. 4 (May 1988). p. 682-690
(7) Warheit, D.B., et al. Pulmonary toxicity assessments of inhaled ethylene oxide/propylene oxide copolymer lubricants in rats. Inhalation Toxicology. Vol. 7, no. 3 (Apr. 1995). p. 377-392
(8) Hoffman, G.M., et al. Acute inhalation toxicity studies in several animal species of an ethylene oxide/propylene oxide copolymer (Ucon 50-HB-5100). Drug and Chemical Toxicology. Vol. 14, no. 3 (Sept. 1991). p. 243-256
(9) Kinkead, E.R., et al. Acute irritation and sensitization potential of Bel-Ray Syncom 1400. Acute Toxicity Data. Vol. 1, no. 3 (1992). p. 221
(10) Bailey, F.E., et al. Polyoxyalkylenes. In: Ullmann's encyclopedia of industrial chemistry. 7th ed. John Wiley and Sons, 2005. Available at: <> (Subscription required)
(11) Clinton, N., et al. 1,2-Epoxide polymers: ethylene oxide polymers and copolymers. In: Encyclopedia of polymer science and engineering. Vol. 6. John Wiley and Sons, 1986. p. 225-273
(12) UCON fluids and lubricants. Union Carbide Corporation, 1996
(13) Mellon Institute of Industrial Research. Initial submission: letter submitting two dietary studies with UCON lubricant 50-HB-5100 in rats with attachments. Date produced: May 13, 1992. Union Carbide Corp. EPA/OTS 88-920002824. NTIS/OTS0539583.
(14) Supplement: Acute inhalation toxicity study with ethylene oxide/propylene oxide copolymers UCON 50 HB-5100, EMKAROX VG680W & EMKAROX VG1050W in rats with cover letter dated 022192. Date produced: Jan. 29, 1992. ICI Americas Inc. EPA/OTS 88-920000195. NTIS/OTS0534745-1.

Information on chemicals reviewed in the CHEMINFO database is drawn from a number of publicly available sources. A list of general references used to compile CHEMINFO records is available in the database Help.

Review/Preparation Date: 2005-03-10

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