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CHEMINFO Record Number: 180
CCOHS Chemical Name: Allyl propyl disulfide

2-Propenyl propyl disulfide
Propyl allyl disulfide
Allyl propyl disulphide
Onion oil

Chemical Name French: Disulfure d'allyle et de propyle
Chemical Name Spanish: Disulfuro de alilpropilo
CAS Registry Number: 2179-59-1
RTECS Number(s): JO0350000
Chemical Family: Organic disulfide / aliphatic disulfide / unsaturated aliphatic disulfide / alkenyl alkyl disulfide / thioperoxide
Molecular Formula: C6-H12-S2
Structural Formula: CH2=CH-CH2-S-S-CH2-CH2-CH3


Appearance and Odour:
Pale yellow liquid with a strong, irritating, onion-like odour.(1,2)

Odour Threshold:
Not available

Warning Properties:
Information not available for evaluation.

Uses and Occurrences:
Allyl propyl sulfide is used as a synthetic flavour and food additive.(2,3)
Allyl propyl disulfide is the chief volatile component of onion oil as well as being a volatile component of chives and garlic.(1,3)


Pale yellow liquid with a strong, irritating, onion-like odour. COMBUSTIBLE LIQUID AND VAPOUR. Liquid can float on water and may travel to distant locations and/or spread fire. During a fire, irritating/toxic sulfur oxides and very toxic/flammable hydrogen sulfide gas may be generated. Closed containers may rupture violently if exposed to fire or excessive heat for a sufficient period of time. SKIN SENSITIZER. May cause an allergic skin reaction. May cause severe eye and skin irritation.


Effects of Short-Term (Acute) Exposure

Allyl propyl disulfide can form a vapour at room temperature, but not readily. It is one of the main components responsible for the odour of onions and garlic. It is well-known to be a strong irritant of the nose, and throat in humans at low concentrations. Workers in an onion dehydration plant who were exposed to 3.4 ppm experienced considerable nose and throat irritation.(7) No other reports of health effects due to exposure to allyl propyl disulfide were located.

Skin Contact:
Allyl propyl disulfide should be treated as a moderate to severe skin irritant, since there is insufficient information available to assess the skin irritation potential of this chemical.
Allyl propyl disulfide is unlikely to cause harmful effects if absorbed through the skin.

Eye Contact:
Allyl propyl disulfide should be treated as a moderate to severe eye irritant, since there is insufficient information available to assess the eye irritation potential of the liquid. The vapour is well known to be a strong irritant of the eyes in humans at low concentrations. Workers in an onion dehydration plant who were exposed to 3.4 ppm experienced considerable eye irritation.(7)

No significant harmful effects were observed in humans following ingestion of 125 mg/kg allyl propyl disulfide.(8) Ingestion is not a typical route of occupational exposure.

Effects of Long-Term (Chronic) Exposure

Skin Sensitization:
Allyl propyl sulfide is an occupational skin sensitizer, based on animal and human experimental evidence. No human occupational case reports were located.
Allyl propyl disulfide, a component of garlic, is one of the chemicals that causes the allergic contact dermatitis in garlic-sensitive individuals. Twenty-three garlic-sensitive people were patch-tested with allyl propyl disulfide in petroleum jelly at 0.5% and at 5.0% for 48 hours. Skin reactions occurred in 6/23 people for the 0.5% concentration, and in 23/23 for the 5.0% concentration.(4)


There is no human or animal information available.

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 or animal information available.

Reproductive Toxicity:
There is no human or animal information available.

There is no human or animal information available. A negative result was obtained for allyl propyl disulfide in a test using bacteria.

Toxicologically Synergistic Materials:
There is no information available.

Potential for Accumulation:
Probably does not accumulate.


If symptoms are experienced, remove source of contamination or move victim to fresh air.

Skin Contact:
Quickly and gently blot or brush away excess chemical. Remove contaminated clothing, shoes, and leather goods (e.g. watchbands, belts). Wash gently and thoroughly with water and non-abrasive soap for 20 minutes or until the chemical is removed. Obtain medical attention immediately. Completely decontaminate clothing, shoes and leather goods before re-use or discard.

Eye Contact:
Quickly and gently blot or brush away excess chemical. Immediately flush the contaminated eye(s) with lukewarm, gently flowing water for 20 minutes or until the chemical is removed, while holding the eyelid(s) open. Take care not to rinse contaminated water into the unaffected eye or onto the face. Obtain medical attention immediately.

If irritation or discomfort occur, obtain medical advice immediately.

First Aid Comments:
Consult a doctor and/or the nearest Poison Control Centre for all exposures except minor instances of inhalation or skin contact.
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:
56 deg C (132.8 deg F) (method not specified) (9)

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:
Probably not sensitive. Stable material.

Sensitivity to Static Charge:
Compared to similar aliphatic disulfides, allyl propyl disulfide probably has a moderately high electrical conductivity and therefore will not accumulate static charge. Allyl propyl disulfide vapour and air in concentrations in the flammable range will probably not be ignited by a static discharge, since it has a moderately high flash point

Electrical Conductivity:
Not available.

Minimum Ignition Energy:
Not available.

Combustion and Thermal Decomposition Products:
Sulfur oxides, hydrogen sulfide gas and carbon monoxide.(2,9)

Fire Hazard Summary:
COMBUSTIBLE LIQUID. Can form explosive mixtures with air at, or above 56 deg C (132.8 deg F). Liquid can float on water and may travel to distant locations and/or spread fire. During a fire, irritating/toxic sulfur oxides and very toxic/extremely flammable hydrogen sulfide gas may be generated. Can accumulate in confined spaces and low-lying areas resulting in a toxicity hazard. Closed containers may rupture violently if exposed to fire or excessive heat for a sufficient period of time.

Extinguishing Media:
Carbon dioxide, dry chemical powder, appropriate foam (3,9), water spray, or fog. Fire fighting foams, such as multipurpose alcohol-resistant foams, are recommended for most flammable liquid fires. 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 protected location. Approach fire from upwind to avoid hazardous vapours and toxic decomposition products.
Closed containers may rupture violently when exposed to the heat of fire and suddenly release large amounts of products. Stay away from ends of tanks, but be aware that flying material (shrapnel) from ruptured tanks may travel in any direction. If possible, isolate materials not yet involved in the fire and move containers from fire area if this can be done without risk. Protect personnel. Otherwise, cool fire-exposed containers, tanks or equipment by applying hose streams. 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. Cooling should continue until well after the fire is out. If this is not possible, use unmanned monitor nozzles and immediately evacuate the area.
If a leak or spill has not ignited, use water spray in large quantities to disperse the vapours, to protect personnel attempting to stop a leak and to flush spills away from ignition sources. Solid streams of water may be ineffective and spread material.
For an advanced or massive fire in a large area, use unmanned hose holders or monitor nozzles; if this is not possible withdraw from fire area and allow fire to burn. Withdraw immediately in case of rising sound from venting safety device or any discolouration of tank.

Protection of Fire Fighters:
Allyl propyl disulfide is a skin sensitizer. Do not enter without wearing specialized protective equipment suitable for the situation. Firefighter's normal protective clothing (Bunker Gear) will not provide adequate protection. A full-body encapsulating chemical protective suit with positive pressure self-contained breathing apparatus (NIOSH approved or equivalent) may be necessary.


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


Molecular Weight: 148.28

Conversion Factor:
1 ppm = 6.05 mg/m3; 1 mg/m3 = 0.165 ppm at 25 deg C (calculated)

Physical State: Liquid
Melting Point: FREEZING POINT: -15 deg C (5 deg F) (2,9)
Boiling Point: Not available at atmospheric pressure.
Relative Density (Specific Gravity): 0.929 at 15 deg C (water = 1) (2,10)
Solubility in Water: Insoluble (2,9)
Solubility in Other Liquids: Soluble in diethyl ether, carbon disulfide and chloroform (2,10)
Coefficient of Oil/Water Distribution (Partition Coefficient): Log P(oct) = 3.70 (estimated) (11)
pH Value: Not applicable
Viscosity-Dynamic: Not available
Surface Tension: Not available
Vapour Density: 5.11 (air=1) (calculated)
Vapour Pressure: 0.05 kPa (0.375 mm Hg) (cited as 50 Pa) at 20 deg C (9)
Saturation Vapour Concentration: 500 ppm (0.05%) at 20 deg C (calculated)
Evaporation Rate: Not available
Henry's Law Constant: Not available


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.

STRONG OXIDIZING AGENTS (e.g. calcium hypochlorite, sodium chlorite, perchloric acid, perchlorates or peroxides) - reaction may be violent. Risk of fire and explosion.(1,9)

Hazardous Decomposition Products:
None reported.

Conditions to Avoid:
Sparks, open flames, heat, hot surfaces and other ignition sources.

Corrosivity to Metals:
No information is available.

Corrosivity to Non-Metals:
No specific information is available. Allyl propyl disulfide may attack some forms of rubber and plastic.


There are no animal toxicity values available.

Skin Sensitization:
Results from a Guinea Pig Maximization Test, using Freund's Complete Adjuvant, indicate that allyl propyl disulfide is one of the chemicals that causes sensitivity to garlic. Animals previously sensitized to garlic or to diallyl sulfide had 1% and 5% allyl propyl disulfide in ethanol applied to their skin. After 24 hours, 0/7 (garlic sensitization) and 0/8 (diallyl sulfide sensitization) animals treated with 1% allyl propyl disulfide showed sensitization, while 7/7 (garlic sensitization) and 8/8 (diallyl sulfide sensitization) animals treated with 5% showed sensitization.(4)


Selected Bibliography:
(1) Occupational Safety and Health Administration (OSHA). Allyl propyl disulfide. In: OSHA Analytical Methods Manual. Revision Date: Oct. 31, 2001. Available from World Wide Web: <>
(2) Allyl propyl disulfide. In: Documentation of threshold limit values and biological exposure indices. 7th ed. American Conference of Governmental Industrial Hygienists, 2001
(3) US National Library of Medicine. Allyl propyl disulfide. Last revision date: 2001-08-09. In: Hazardous Substances Data Bank (HSDB). CHEMpendium. [CD-ROM]. Canadian Centre for Occupational Health and Safety (CCOHS). Issue: 2002-4. Also available from World Wide Web: <>
(4) Papageorgiou, C., et al. Allergic contact dermatitis to garlic (Allium sativum L.). Identification of the allergens: the role of mono-, di-, and trisulfides present in garlic: a comparative study in man and animal (guinea-pig). Archives of Dermatology Research. Vol. 275, no. 4 (1983). p. 229-234
(5) Zeiger, E., et al. Salmonella mutagenicity tests: IV. Results from the testing of 300 chemicals. Environmental and Molecular Mutagenesis. Vol. 11, suppl. 12 (1988). p. 1-158
(6) Occupational safety and health guideline for allyl propyl sulfide. Occupational safety and health guidelines for chemical hazards. Supplement III-OHG. DHHS (NIOSH) Publication No. 92-110, suppl. III-OHG. National Institute for Occupational Safety and Health, 1992
(7) Feiner, B., et al. An industrial hygiene survey of an onion dehydrating plant. Industrial Hygiene and Toxicology. Vol. 28 (1946). p. 278-279
(8) Augusti, K.T., et al. Effect of essential oil of onion (allyl propyl disulphide) on blood glucose, free fatty acids and insulin levels of normal subjects. Clinica Chimica Acta. Vol. 60 (1975). p. 121-123
(9) Allyl propyl disulfide. International Chemical Safety Cards (WHO/IPCS/ILO). ICSC: 1422. IPCS CEC 2002. National Institute for Occupational Safety and Health. Available from World Wide Web: <>
(10) Lewis, Sr., R.J., ed. Allyl propyl disulfide. Hawley's condensed chemical dictionary. [CD-ROM]. 14th ed. John Wiley and Sons, Inc., 2002
(11) Syracuse Research Corporation. Interactive LogKow (KowWin) Database Demo. Date unknown. Available from World Wide Web: <>

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: 2004-10-15

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