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SECTION 1. CHEMICAL IDENTIFICATION

CHEMINFO Record Number: 98
CCOHS Chemical Name: n-Pentane

Synonyms:
Amyl hydride
Normal pentane
Pentane (non-specific name)

Chemical Name French: Pentane normal
Chemical Name Spanish: n-Pentano
CAS Registry Number: 109-66-0
UN/NA Number(s): 1265
RTECS Number(s): RZ9450000
EU EINECS/ELINCS Number: 203-692-4
Chemical Family: Saturated aliphatic hydrocarbon / paraffin / alkane / pentane isomer
Molecular Formula: C5-H12
Structural Formula: CH3-(CH2)3-CH3

SECTION 2. DESCRIPTION

Appearance and Odour:
Colourless liquid with a sweet or gasoline-like odour.(17,18)

Odour Threshold:
Reported values vary widely and are not reliable; 119-1147 ppm (unspecified) (18)

Warning Properties:
POOR - reported odour thresholds are unreliable and are about the same magnitude as, or above the TLV.

Composition/Purity:
Reagent and higher grades of n-pentane are at least 95% pure and are not odourized. Some of the impurities that may be present are sulfur, water, C4-C5 saturated hydrocarbons, unsaturated hydrocarbons, and trace amounts of benzene and other aromatic compounds.(19,44) Grades of greater than 95% may contain traces (generally less than 10 ppm) of benzene while lower grades may contain approximately 0.1% of benzene. Consult with your supplier regarding product purity.

Uses and Occurrences:
n-Pentane is used in the production of gasoline blends, in aerosols, in low temperature thermometers, as a blowing agent in foams (e.g. expandable polystyrene), and as a solvent. The main sources of n-pentane are oil and natural gas fields. n-Pentane is also generated as a by-product when crude oil is refined.(20,26)


SECTION 3. HAZARDS IDENTIFICATION

EMERGENCY OVERVIEW:
Colourless liquid with a sweet or gasoline-like odour. EXTREMELY FLAMMABLE, HIGHLY VOLATILE LIQUID. Can accumulate static charge. Vapour is heavier than air and may spread long distances and will accumulate at low points (e.g. open or closed drains). Liquid can float on water and may travel to distant locations or spread fire. Distant ignition and flashback are possible. Essentially non-toxic below the lower explosive limit. Can accumulate in confined spaces, resulting in a fire and toxicity hazard. Asphyxiant. Very high vapour concentrations can displace oxygen in the air, especially in a confined space, and could result in life-threatening asphyxiation (suffocation). Aspiration hazard. Swallowing or vomiting of the liquid may result in aspiration (breathing) into the lungs. NOTE: Some grades of n-pentane may contain benzene, which is carcinogenic. If benzene is present in n-pentane at a concentration of more than 0.1%, the mixture is considered carcinogenic. For more information, refer to the CHEMINFO review of benzene.



POTENTIAL HEALTH EFFECTS

Effects of Short-Term (Acute) Exposure

Inhalation:
n-Pentane readily forms very high vapour concentrations at room temperature. It is extremely flammable and is not expected to produce significant harmful effects below the lower explosive limit (15000 ppm (1.5%). Based on animal information, high concentrations of n-pentane may cause temporary irritation of nose and throat and depression of the central nervous system (CNS) with symptoms such as headache, nausea, dizziness, drowsiness, and confusion. In one study, no symptoms were reported by volunteers exposed to up to 5000 ppm pentane (76.5% n-pentane, 20.8% isopentane; 1.3% butanes and 1.4% hexanes) for 10 minutes.(1)

n-Pentane vapour concentrations can become so high that oxygen is displaced, especially in a confined space. Life-threatening asphyxiation (suffocation) may result. The available oxygen should be a minimum of 18% or harmful effects will result.(3,4)
Effects of oxygen deficiency are: 12-16% - breathing and pulse rate are increased, with slight muscular incoordination; 10-14% - emotional upsets, abnormal fatigue from exertion, disturbed respiration; 6-10% - nausea and vomiting, inability to move freely, collapse, possible lack of consciousness; below 6% - convulsive movements, gasping, possible respiratory collapse and death. Since exercise increases the body's need for oxygen, symptoms will occur more quickly during exertion in an oxygen-deficient environment.(3,4) Survivors of oxygen deprivation may show damage to some or all organs including the central nervous system and the brain. These effects may or may not be reversible with time, depending on the degree and duration of the low oxygen and the amount of tissue injury.(4)

Skin Contact:
Direct contact with n-pentane may cause slight irritation based on human and animal information. n-Pentane will quickly evaporate from the skin. Fifteen minutes after application of 2.0 mL of undiluted n-pentane to 15 volunteers, a semi-occluded patch was applied and left in place for 24 hours. Grade 1 redness was observed in 4 individuals 24 hours after the patch was removed. The other 11 individuals showed no evidence of irritation (average score: 0.27/8).(34)
If n-pentane is trapped on the skin, it may produce severe irritation and delayed effects, based on limited human information. In a historical report, volunteers experienced a painful burning sensation, itching, redness and swelling during a 1-hour skin application of pentane (purity not specified). Redness and pain developed about 1 hour after exposure and peaked after 4 days. Blisters formed when pentane was applied to the thigh for 5 hours. All effects were reversible and no scars resulted.(5,6)

Eye Contact:
Direct contact with the liquid may cause mild, temporary eye irritation based on animal information. No irritation was experienced by volunteers exposed to up to 5000 ppm pentane vapour (76.5% n-pentane, 20.8% isopentane; 1.3% butanes and 1.4% hexanes) for 10 minutes.(1)

Ingestion:
In general, n-pentane is not expected to be toxic if ingested, based on limited animal information. Although there are no case reports of aspiration, n-pentane is expected to be an aspiration hazard based on its physical properties (viscosity and surface tension). Aspiration refers to the inhalation of liquid into the lungs during ingestion or vomiting. Severe lung irritation, damage to the lung tissues and death may result. Ingestion is not a typical route of occupational exposure.

Effects of Long-Term (Chronic) Exposure

Repeated skin contact can cause painful dryness, redness and itching (dermatitis). n-Pentane is not expected to be an occupational sensitizer.
The available information does not suggest that n-pentane causes nervous system effects (peripheral neuropathy) similar to n-hexane. No conclusions can be drawn from a single case report of liver injury involving exposure to an adhesive containing a small amount of pentane.

Nervous System:
The available information does not suggest that n-pentane causes nervous system effects (peripheral neuropathy) similar to n-hexane.
A single published report describes 3 female workers who developed signs of peripheral neuropathy following exposure to a product containing 5% n-hexane, 14% n-heptane, and 80% n-pentane.(2) Even though n-hexane comprised a small amount of the product, it is likely that it was responsible for the observed effects. Nervous system effects have not been observed in animal studies designed to assess this effect.

Skin:
Repeated contact can remove natural oils from the skin, resulting in painful dryness, redness and itching (dermatitis).

Skin Sensitization:
n-Pentane is not expected to be an occupational sensitizer.
No human case reports were located. Negative results were obtained in one animal study.

Liver:
No conclusions can be drawn from a single case report of liver injury involving exposure to an adhesive containing a small amount of pentane.
A 63-year-old man developed signs of liver injury (abnormal liver function test results). He had been exposed to an adhesive 3 hours/time, 2-3 times/week for approximately 2 years in a poorly ventilated garage. During this time, he experienced symptoms of drowsiness and nausea. The adhesive contained a propane/butane/isobutane propellant (30-35%), petroleum distillates (25-35%), pentane (10-15%) and acetone (1-5%). He stopped using the adhesive and liver tests returned to normal within 4 weeks.(41)

Carcinogenicity:

There is no specific human or animal information available for n-pentane. n-Pentane may contain small amounts of benzene, a known human carcinogen. Consult your supplier regarding the purity of the material you are using.

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 not assigned a carcinogenicity designation to this chemical.

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

Teratogenicity and Embryotoxicity:
There is no human information available. The information available from animal studies does not suggest that n-pentane causes developmental toxicity.

Reproductive Toxicity:
There is no human information available. There are no results from one- or two-generation animal toxicity tests available, but no effects were noted in a 90-day study that included detailed examination of the reproductive organs.

Mutagenicity:
The available information indicates that n-pentane is not mutagenic. There is no human information available. Negative results were obtained in tests using live animals, cultured mammalian cells and bacteria.

Toxicologically Synergistic Materials:
No information was located.

Potential for Accumulation:
Unlikely to accumulate. n-Pentane is readily metabolized and excreted. Humans breathing 100 ppm n-pentane initially metabolized 45% and exhaled 55% unchanged.(7, unconfirmed)


SECTION 4. FIRST AID MEASURES

Inhalation:
This is chemical is extremely flammable. Take proper precautions (e.g. remove any sources of ignition). In general, this gas has very low toxicity, but it can act as an asphyxiant at high concentrations. If the victim has been knocked down, wear appropriate protective equipment, and use the buddy system. Remove source of contamination or move victim to fresh air. If breathing is difficult, trained personnel should administer emergency oxygen. If breathing has stopped, trained personnel should begin artificial respiration (AR) or, if the heart has stopped, cardiopulmonary resuscitation (CPR) or automated external defibrillation (AED) immediately. Quickly transport victim to an emergency care facility.

Skin Contact:
Quickly and gently blot or brush away excess chemical. Wash gently and thoroughly with lukewarm, gently flowing water and non-abrasive soap for 5 minutes. If irritation persists, obtain medical advice.

Eye Contact:
Quickly and gently blot away excess chemical. Immediately flush the contaminated eye(s) with lukewarm, gently flowing water for 5 minutes, while holding the eyelid(s) open. If irritation persists, obtain medical advice.

Ingestion:
NEVER give anything by mouth if the victim is rapidly losing consciousness, is unconscious or is convulsing. DO NOT INDUCE VOMITING. If vomiting occurs naturally, have victim lean forward to reduce risk of aspiration. Have victim rinse mouth with water again. Immediately obtain medical attention.

First Aid Comments:
Provide general supportive measures (comfort, warmth, rest).
Consult a doctor and/or the nearest Poison Control Centre for all exposures except minor instances of inhalation or skin contact.
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.



SECTION 5. FIRE FIGHTING MEASURES

Flash Point:
Less than -40 deg C (closed cup) (22)

Lower Flammable (Explosive) Limit (LFL/LEL):
1.5% (22)

Upper Flammable (Explosive) Limit (UFL/UEL):
7.8% (22)

Autoignition (Ignition) Temperature:
260 deg C (500 deg F) (22)

Sensitivity to Mechanical Impact:
Not sensitive.

Sensitivity to Static Charge:
n-Pentane can accumulate electrostatic charge by flow, friction in pipes, splashing or agitation. n-Pentane in the flammable range can be easily ignited by an electrostatic discharge of sufficient energy (e.g. brush discharge).

Electrical Conductivity:
Reported as less than 2 x 10(-8) S/m (less than 2 x 10(4) pS/m) at 20 deg C.(21) However, the electrical conductivity is expected to be less then 50 pS/m, based on n-pentane's chemical properties, and dielectric constant, and the electric conductivity for pure n-hexane (1 x 10 (-5) pS/m) (22), a closely related compound.

Minimum Ignition Energy:
0.22 mJ (25); 0.28 mJ for 3.3% by volume (22)

Combustion and Thermal Decomposition Products:
Carbon monoxide, carbon dioxide, water and toxic and irritating fumes.

Fire Hazard Summary:
EXTREMELY FLAMMABLE, HIGHLY VOLATILE LIQUID. Readily forms explosive mixtures with air, which are easily ignited by a static charge. Accumulates static charge. Vapours are heavier than air and can travel over long distances and will create a flash back hazard. The vapours also accumulate in confined spaces and low areas, resulting in an explosion or toxicity hazard. Liquid n-pentane floats on top of water and therefore it can be spread quickly over large area. Heat from a fire can cause a rapid build-up of pressure inside containers, which may cause explosive rupture and a sudden release of large amounts of extremely flammable vapours. Drums have no safety devices and will violently rupture on exposure to fire.

Extinguishing Media:
Dry chemical powder and foam. Foam manufacturers should be consulted for recommendations regarding types of foams and application rates. Water will be ineffective because it will not cool n-pentane below its flash point.(28,29)

Extinguishing Media to be Avoided:
Carbon dioxide, low expansion foams, and direct application of water on n-pentane liquid. Under certain conditions, discharge of carbon dioxide produces electrostatic charges that could create a spark and ignite n-pentane.(23,29)

Fire Fighting Instructions:
Evacuate area. Fight fire from a protected location or maximum distance possible. Approach fire from upwind to avoid toxic decomposition products.
For fires involving very volatile flammable liquids, the best procedure is to stop the leak before attempting to extinguish the fire. It is extremely dangerous to extinguish the fire, while allowing the leak to continue. The vapours could form an explosive mixture with air and re-ignite resulting in a sudden violent flash fire, which may cause far more damage than if the original fire had been allowed to burn. In some cases, extinguishing the fire with dry chemical powder may be necessary to permit immediate access to valves to shut off the leak. However, this must be done carefully. If it is not possible to stop the leak or if the vapours are burning at the safety valves do not extinguish the flame. It is safer to let the vapor burn at the valves or point of leakage, and if there is no risk to the surrounding area, allow the fire to continue burning while protecting exposed materials with water spray to prevent ignition of other combustible materials.
DO NOT apply solid streams of water directly on liquid n-pentane. n-Pentane floats on water runoff and can easily spread over large areas creating a massive fire hazard. n-Pentane fires may be controlled with foam blankets or water spray. The resulting solutions may be flammable. Dike for appropriate disposal of these solutions.
Heat from a fire can cause a rapid build-up of pressure inside containers, which may cause explosive rupture. Withdraw immediately in case of rising sound from venting safety device or any discolouration of tank due to fire.
Cool fire-exposed containers by applying hose streams, to minimize the risk of rupture. Cooling should begin as soon as possible (within several minutes) and should concentrate on any unwetted portions of the container. Apply water from the side and a safe distance. Stay away from ends of tanks, but be aware that flying material (shrapnel) from containers may travel in any direction. Cooling should continue until well after the fire is out.
For an advanced or a massive fire in a large area, use unmanned hose holder or monitor nozzles; if this is not possible withdraw from fire area and allow fire to burn.
After the fire has been extinguished, the resulting solutions of n-pentane may be flammable. Explosive atmospheres may be present. Before entering such an area, especially confined areas, check the atmosphere with an appropriate monitoring device while wearing full bunker gear and self-contained breathing apparatus. Containers that have been involved in a fire should not be approached until they have been completely cooled down.

Protection of Fire Fighters:
n-Pentane is slightly hazardous to health. However, it can displace oxygen, reducing the amount available for breathing. Firefighters may enter the area if positive pressure self-contained breathing apparatus (NIOSH approved or equivalent) and full Bunker Gear is worn.



NATIONAL FIRE PROTECTION ASSOCIATION (NFPA) HAZARD IDENTIFICATION

NFPA - Health: 1 - Exposure would cause significant irritation, but only minor residual injury.
NFPA - Flammability: 4 - Will rapidly or completely vaporize at atmospheric pressure and normal ambient temperature, or readily disperse in air and burn readily.
NFPA - Instability: 0 - Normally stable, even under fire conditions, and not reactive with water.

SECTION 9. PHYSICAL AND CHEMICAL PROPERTIES

Molecular Weight: 72.15

Conversion Factor:
1 ppm = 2.94 mg/m3; 1 mg/m3 = 0.34 ppm at 25 deg C (calculated)

Physical State: Liquid
Melting Point: -130 deg C (-202 deg F) (11)
Boiling Point: 36 deg C (97 deg F) (11)
Relative Density (Specific Gravity): 0.626 at 20 deg C (water = 1) (21)
Solubility in Water: Practically insoluble (38 mg/L at 25 deg C) (11)
Solubility in Other Liquids: Miscible with ethanol, acetone and diethyl ether and expected to be very soluble in other non-polar solvents like toluene, methylene chloride, and chloroform. Expected to be slightly soluble or not soluble in polar solvents like methanol.(21)
Coefficient of Oil/Water Distribution (Partition Coefficient): Log P(oct) = 3.39 (11)
pH Value: Not applicable
Viscosity-Dynamic: 0.23 mPa.s (0.23 centipoises) at 20 deg C (24); 0.22 mPa.s (0.22 centipoises) at 25 deg C (21)
Viscosity-Kinematic: 0.37 mm2/s ( 0.37 centistokes) at 20 deg C (calculated)
Saybolt Universal Viscosity: 26.8 Saybolt Universal Seconds at 37.8 deg C (100 deg F) (calculated)
Surface Tension: 16 mN/m (16 dynes/cm) at 20 deg C (21); 15.45 mN/m (15.45 dynes/cm) at 25 deg C (calculated) (21)
Vapour Density: 2.48 (air = 1) (calculated)
Vapour Pressure: 65.1 kPa (488 mm Hg) at 20 deg C (27); 68.5 kPa (514 mm Hg) at 25 deg C (11)
Vapour Pressure at 50 deg C: 164 kPa (1229 mm Hg) (calculated) (21)
Saturation Vapour Concentration: 642000 ppm (64.2%) at 20 deg C; 676000 ppm (67.6%) at 25 deg C (calculated)
Evaporation Rate: 12.4-13 (butyl acetate = 1) (27)
Henry's Law Constant: 1.27 X 10(5) Pa.m3/mol (cited as 1.25 atm.m3/mol) at 25 deg C (11); log H = 1.71 (dimensionless constant; calculated)

Other Physical Properties:
DIELECTRIC CONSTANT: 1.84 at 20 deg C (21)


SECTION 10. STABILITY AND REACTIVITY

Stability:
Normally stable

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.


The risk of a hazardous incident occurring due to accidental mixing of n-pentane with other substances is low because n-pentane only reacts with a very small number of chemical classes that are commonly used in the workplace. If an accidental mixing does occur, these few reactions may be severe.

STRONG OXIDIZING AGENTS (e.g. peroxides, perchlorates) - Increases the risk of fire and explosion. Reaction may be delayed.(30)
HALOGEN COMPOUNDS (e.g. chlorine, and bromine) - Risk of fire and explosion. Fluorine gas reacts explosively.(48) Mixtures with around 20% or more of chlorine are explosive. However, if any mixture of n-pentane and chlorine gas is exposed to direct sunlight there is almost always an explosion.(49) The presence of some metallic salts or oxides (e.g. ferric chloride, copper oxide) or metals (e.g. mercury, zinc) increases the reactivity with the halogen compounds.(30,49,50) Reaction with iodine is not vigorous.

Hazardous Decomposition Products:
None

Conditions to Avoid:
Heat, open flames, static discharge, sparks and other ignition sources.

Corrosivity to Metals:
n-Pentane is not corrosive to aluminum or carbon steel.(51)

Corrosivity to Non-Metals:
n-Pentane is corrosive to polypropylene, acrylonitrile butadiene styrene (ABS), polyurethane, and high-density polyethylene (HDPE). It is slightly corrosive to polyvinyl chloride, polyacetals, and polyester. n-Pentane is not corrosive to fluorinated plastics, most polyamides, polycarbonate, thermoset epoxy, and polystyrene.(52)


SECTION 11. TOXICOLOGICAL INFORMATION

LC50 (rat): greater than 6106 ppm (4-hour exposure) (7, unconfirmed)
LC50 (rat): 117000 ppm (4-hour exposure); cited as 364 gm/m3 (4-hour exposure) (12, unconfirmed)

LD50 (oral, rat): greater than 2000 mg/kg (34)

Eye Irritation:

n-Pentane is a slight eye irritant.

In a well-conducted test, application of 0.1 mL n-pentane caused limited and temporary irritation in rabbits (range: 2-4/110 with average score: 1.33/110 at 24 hours; by 72 hours the eyes had completely cleared).(34)

Skin Irritation:

n-Pentane is a slight skin irritant.

In a test described as compliant with OECD test protocols, n-pentane produced some limited, transient irritation in rabbits. Forty-five minutes after administration, grade 1 or 2 redness was exhibited in most animals. One animal also had grade 2 swelling. At 24 hours, 4 animals still exhibited some redness (average score 0.83/110) and 1 animal had grade 1 swelling. At 48 hours, 1 animal still had grade 2 redness (average score 0.33/110), which was still present at 72 hours, but gone by day 7. The overall primary irritation score was 0.67/110).(34,44) In a study that evaluated the potential skin irritancy of a large number of aliphatic hydrocarbons, n-pentane was not tested due to its very high vapour pressure (saturated vapour concentration: 67.4%).(35)

Effects of Short-Term (Acute) Exposure:

Inhalation of extremely high concentrations of n-pentane causes depression of the central nervous system (CNS) and irritation of the nose and throat.

Inhalation:
No respiratory irritation was observed in male mice exposed head-only to 5559 ppm n-pentane for 1-minute, with a 10-minute recovery and a repeat 1-minute exposure.(7, unconfirmed) In a test to evaluate the anesthetic activity of n-pentane, mice (6-11/group) were exposed to 70000-110000 ppm (cited as 7-11%) n-pentane for up to 2 hours. Light anesthesia (inability to remain upright) was observed following exposure to 7% for 10 minutes. Death was observed in 5/11 exposed to 10% and 9/10 exposed to 11% for 2 hours. Recovery of survivors occurred in 1-2 minutes.(32) Severe central nervous system depression (deep anesthesia) and death of 1/4 mice was observed following inhalation of 128000 ppm for 5 minutes. No harmful effects were observed at 16000 ppm.(13) In another study, severe central nervous system depression was observed in mice exposed to 92000-129000 ppm (cited as 0.27-0.38 g/litre) for 28-116 minutes. One mouse died after 37 minutes at the highest exposure level.(14) The lowest concentrations that caused mice to lay down due to central nervous system effects was 68000-102000 ppm (cited as 200-300 mg/litre) for 2 hours.(5, unconfirmed) No apparent effects were observed in rats exposed to 0, 1700, 3400 or 6800 ppm (cited as 0, 5000, 10000 or 20000 mg/m3) for 5 days (6 hr/d). Parameters evaluated included survival, body weight changes, clinical observations and gross post-mortem examination.(34) Male rats were exposed to 0, 1000, 3000 or 10000 ppm n-pentane for two weeks (6 hr/d; 5 d/wk). In a preliminary range finding study, 4 male rats exposed to 10000 ppm for 4 days (6 hr/d) showed no clinical signs of toxicity. In the main study, there were no clinical signs of toxicity, and growth and performance on behavioural tests was similar to controls. Increases in serum calcium and phosphate concentrations were seen in rats following the 10th exposure to 3000 or 10000 ppm. These effects reversed during a two week recovery period. Autopsy showed no significant effects in rats exposed to up to 10000 ppm.(43) No signs of toxicity or harmful effects on the kidney were observed in male rats exposed to 44-4437 ppm of a mixture of C4 and C5 hydrocarbons (including 25% by weight n-pentane) for 21 days.(15) Exposure of mice to less than 10000 ppm n-pentane slightly increased responding in a behavioral test (operant responding). Higher concentrations decreased responding in a concentration-dependant manner, with a 50% decrease at 30000 ppm and a 100% decrease at 56000 ppm. Recovery occurred completely 30 minutes after exposure to 56000 ppm stopped.(42) In two unpublished studies, rats (8/group) were exposed to 0, 675, 2200 or 6800 ppm n-pentane for 3 consecutive days (8 hr/d) and assessed for behavioural effects. In the first study, exposure to n-pentane did not cause any dose-related effects in a standardized functional observational battery (FOB) or motor activity measurements. In the second study, mild and reversible changes in measures of learned behaviour were reported. In both studies, no changes in body weights or remarkable clinical signs were noted.(44, unconfirmed)

Ingestion:
Deaths, reduced body weight, reduced activity, stomach irritation and reduced kidney weight were observed in male rats following oral administration of 500 mg/kg/day or 2000 mg/kg/day for one month.(16)

Effects of Long-Term (Chronic) Exposure:

Inhalation:
No neurobehavioural effects (normal motor activity and no evidence of peripheral neuropathy) were observed in male rats (7/group) exposed to 3000 ppm for 16 weeks (12 h/d, 7 d/wk).(33,36) In another study, no evidence of neurotoxicity was observed in male rats (6-9/group) exposed to 3000 ppm n-pentane for up to 30 weeks (9 h/d, 5 d/wk). Nerve tissues examined histologically showed no "giant axonal degeneration". A decrease in body weight was observed in exposed rats.(37) These studies are limited by the small number of animals/group and the use of only one exposure group. Rats exposed to 0, 1000 or 4500 ppm of a 50:50 mixture of n-butane and n-pentane for 13 weeks (6h/d, 5d/wk) showed no significant effects, and no treatment-induced kidney damage in either sex. A significant reduction in body weight was noted in both sexes by weeks 3 and 4, with males, but not females, recovering by 13 weeks.(38) No treatment related effects were observed in rats exposed to 0, 1700, 3400 or 6800 ppm (cited as 0, 5000, 10000 or 20000 mg/m3) for 90 days (6 hr/d; 5 d/wk). Detailed observation of the animals was conducted including blood and serum chemistry, and microscopic examination of the tissues.(34)

Skin Sensitization:
No sensitization reactions (0/20) were observed in a Magnusson-Kligman Guinea Pig Maximization Test. A positive control was used.(34)

Teratogenicity, Embryotoxicity and/or Fetotoxicity:
The information available does not suggest that n-pentane causes developmental toxicity.
No significant developmental effects were observed in the offspring of rats orally exposed to 0, 100, 500, or 1000 mg/kg/day in corn oil on days 6-15 of pregnancy. There were no significant signs of maternal toxicity.(7,34,44) Rats (7 or 8/group) were exposed by inhalation to 0, 1000, 3000 or 10000 ppm n-pentane on days 6-15 of pregnancy. Oxygen concentrations were maintained at 21%. There were no signs of maternal or developmental toxicity.(40) This study is limited by the small number of animals/group.

Reproductive Toxicity:
The available information does not suggest that n-pentane causes reproductive toxicity.
No standard reproductive toxicity studies were located. No statistically different changes in reproductive organ weights were observed in male or female rats exposed to 0, 1700, 3400 or 6800 ppm (cited as 0, 5000, 10000 or 20000 mg/m3) for 90 days (6 hr/d; 5 d/wk). Detailed observation of the animals was conducted.(34)

Mutagenicity:
n-Pentane is not mutagenic, based on tests using live animals, cultured mammalian cells and bacteria.
Negative results (bone marrow micronucleus formation) were observed in rats exposed by inhalation to 0, 1700, 3400 or 6800 ppm (cited as 0, 5000, 10000 or 20000 mg/m3) for 90 days (6 hr/d; 5 d/wk).(34) Negative results (dominant lethal test) were also obtained in mice exposed by intraperitoneal injection to 48-666 mg/kg n-pentane.(7,8) This route of exposure is not relevant to occupational situations.
Negative results (chromosomal aberrations) were obtained in a study where Chinese Hamster Ovary cells were incubated with n-pentane, with and without metabolic activation. Positive results were obtained in a repeat of the 20-hour harvest in the presence of metabolic activation. The concentrations used were cytotoxic.(34) Negative results (gene mutation) were obtained in Salmonella typhimurium, with and metabolic activation.(39, 44, unconfirmed)


SECTION 16. OTHER INFORMATION

Selected Bibliography:
(1) Patty, F.A., et al. Odor intensity and symptoms produced by commercial propane, butane, pentane, hexane and heptane vapor. US Bureau of Mines Report of Investigations, No. 2979. United States Bureau of Mines, Dec. 1929
(2) Gaultier, M., et al. Polyneuritis and aliphatic hydrocarbons. Journal of European Toxicology. Vol. 6 (1973). p. 294-296
(3) Leikauf, G.D., et al. Inorganic compounds of carbon, nitrogen and oxygen. In: Patty's Toxicology. 5th ed. Vol. 3. Edited by E. Bingham, et al. John Wiley & Sons, 2001
(4) Wilkenfeld, M. Simple asphyxiants. In: Environmental and Occupational Medicine. 3rd ed. Edited by W.N. Rom. Lippincott-Raven Publishers, 1998. p. 651-655
(5) NIOSH. Criteria for a recommended standard: occupational exposure to alkanes (C5-C8). National Institute for Occupational Safety and Health, Mar. 1977
(6) Oettel, H. Effect of organic liquids on the skin. Archiv fuer Experimentelle Pathologie. English translation. Vol. 83 (1936). p. 641-696 (English translation: NIOSHTIC Control Number: 00071886)
(7) Galvin, J.B., et al. n-Pentane CAS # 109-66-0. Journal of Toxicology and Environmental Health, Part A. Vol. 58 (1999). p. 35-56
(8) Epstein, S.S., et al. Detection of chemical mutagens by the Dominant Lethal Assay in the mouse. Toxicology and Applied Pharmacology. Vol. 23 (1972). p. 288-325
(9) Forsberg, K., et al. Quick selection guide to chemical protective clothing. 4th ed. Van Nostrand Reinhold, 2002
(10) European Communities. Commission Directive 98/98/EC. Dec. 15, 1998
(11) Syracuse Research Corporation. The Physical Properties Database (PHYSPROP). Interactive PhysProp Database Demo. Date unknown. Available at: <www.syrres.com/esc/physdemo.html>
(12) MDL Information Systems, Inc. Pentane. Last updated: 2004-05. In: Registry of Toxic Effects of Chemical Substances (RTECS(R)). [CD-ROM]. Canadian Centre for Occupational Health and Safety (CCOHS). Also available at: <ccinfoweb.ccohs.ca/rtecs/search.html> {Subscription required}
(13) Swann, H.E., Jr., et al. Acute inhalation toxicology of volatile hydrocarbons. American Industrial Hygiene Association Journal. Vol. 35, no. 9 (Sept. 1974). p. 511-518
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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: 2005-07-03



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