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CHEMINFO Record Number: 361
CCOHS Chemical Name: Naphthalene

Tar camphor
White tar

Chemical Name French: Naphtalène
Chemical Name Spanish: Naftaleno
CAS Registry Number: 91-20-3
UN/NA Number(s): 1334 2304
RTECS Number(s): QJ0525000
EU EINECS/ELINCS Number: 202-049-5
Chemical Family: Aromatic hydrocarbon / bicyclic aromatic hydrocarbon
Molecular Formula: C10-H8


Appearance and Odour:
White crystalline solid with distinctive odour of mothballs or coal tar

Odour Threshold:
Odour is perceptible at 0.3 to 0.9 ppm.

Warning Properties:
Good - TLV is more than 10 times the odour threshold. Eye irritation is noticeable at 15 ppm.

Coal tar naphthalene is about 90-95% naphthalene, 1-3% thionaphthene, 1-2% dimethylnaphthalene and traces of indenes, tar acids and tar bases. Petroleum naphthalene is a high purity petrochemical feedstock (purity not specified).

Uses and Occurrences:
Current use is mainly as a raw material for the production of phthalic anhydride. Former uses as a moth repellant, wood preservative, soil fumigant, veterinary product and pharmaceutical.


White crystalline solid with distinctive odour of mothballs or coal tar. FLAMMABLE SOLID. May form explosive dust-air mixtures. Dust, fumes or vapour may be irritating to respiratory tract. High vapour concentrations may cause headache, nausea, dizziness, confusion, vomiting and abdominal pain. POSSIBLE CANCER HAZARD - may cause cancer, based on animal information.


Effects of Short-Term (Acute) Exposure

Little information is available on the effects of inhaled naphthalene on human health. Case reports of exposure to naphthalene usually involved the use of mothballs or flakes reported to consist of naphthalene.(16) Hemolytic anemia (destruction of red blood cells) is the primary health concern for humans exposed to naphthalene for either short or long periods of time. Other effects commonly found include nausea, profuse perspiration, vomiting, diarrhea, kidney damage, jaundice (yellowish skin and eyes) and liver damage. Optic neuritis (inflammation of the optic nerve) has been observed. Cataracts have also occurred. Two case studies have reported ocular effects (predominantly cataracts) in workers exposed to naphthalene. Inhalation was assumed to be the primary route of exposure.(8,16) Inhaled dust, fumes or vapour may cause irritation of the nose and throat. Headache, nausea, malaise, confusion, vomiting, abdominal pain and kidney disease (effects not described) were reported in several individuals exposed to naphthalene from large numbers of mothballs (300-500) in their homes.(16)

Skin Contact:
Pure naphthalene may cause mild skin irritation. Crude, unrefined naphthalene may be moderately irritating. Some people may be hypersensitive to naphthalene and develop severe skin rash (itching, swelling, reddening) on contact.(10) The incidence of skin hypersensitivity does not appear to be widespread in the general population, based on the long history of use of naphthalene as a consumer product. This effect is largely confined to industrial exposure where coal tar contamination may be present.
Health effects have been reported in infants through skin absorption of naphthalene, which may have been facilitated by applications of baby oil.(10)

Eye Contact:
Particles of naphthalene may cause reversible eye injury if they remain in prolonged contact with the eye.(8)
Distinct eye irritation occurs at vapour concentrations above 15 ppm (4,7,9). It has been suggested that continued exposure at this level or higher may result in fairly serious eye effects.(7)

The most common situations where ingestion of naphthalene has occurred have been suicide attempts, accidental ingestion of contaminated food and ingestion of mothballs by children. Hemolytic anemia and jaundice are the most common reported adverse effects of the ingestion of naphthalene. Other effects reported include gastrointestinal effects such as nausea, vomiting, diarrhea, abdominal pain and gastrointestinal bleeding, renal effects, neurologic effects such as changes in behaviour, convulsions and coma and liver injury. Blood in urine and reduced urine production have also been noted. The renal, neurologic and liver effects may be secondary to the hemolytic anemia.(16)
Death has occurred after ingestion, but cessation of exposure and the use of blood transfusions have increased the survival rate.(16) Fatalities among children who have eaten mothballs have been reported.(9,10) A mean lethal dose in non-sensitive adults has been estimated at about 5-15 g.(10) Ingestion is not a typical route of occupational exposure.

Effects of Long-Term (Chronic) Exposure

Naphthalene is a possible carcinogen, based on animal evidence.

Prolonged or repeated contact may cause dermatitis (itching, redness, scaling and crusting).

Skin Sensitization:
It is not possible to conclude that naphthalene is an occupational skin sensitizer.
Some people may be hypersensitive to naphthalene and develop severe skin rash (itching, swelling, reddening) on contact.(10) The incidence of skin hypersensitivity does not appear to be widespread in the general population, based on the long history of use of naphthalene as a consumer product. Dermatitis seems to develop more often among persons working with crude coal tar naphthalene, and may be due primarily to contaminants in the naphthalene.(9)

Cases of eye injury, including rare cases of corneal ulceration and cataracts, have been reported as a result of long-term exposure to naphthalene by inhalation or ingestion.(4,7,8,9,16)

Blood/Blood Forming System:
Increased susceptibility to naphthalene poisoning has been reported in individuals with an inherited metabolic deficiency related to enzyme activity of red blood cells.(10)


It has recently been concluded that naphthalene is possibly carcinogenic to humans (IARC Group 2B), based on animal evidence. Exposure of rats by inhalation has been associated with cancer of the olfactory epithelium and nasal respiratory epithelium. These tumours are considered rare in unexposed rats. In addition, a screening assay using only female mice exposed by inhalation showed an increase in lung tumours and an inhalation study with mice showed bronchiolo-alveolar tumours in female mice. An apparent increase in the incidence of bronchiolo-alveolar tumours in male mice was not statistically significant.(21)

Limited human information is available. Six cases of malignant tumours among 15 workers exposed to naphthalene and coal tar over 32 years have been reported. All were smokers and all were exposed to coal tar as well as naphthalene.(14) IARC has concluded that there is inadequate evidence for the carcinogenicity of naphthalene in humans.(21)

The International Agency for Research on Cancer (IARC) has concluded that this chemical is possibly carcinogenic to humans (Group 2B).

The American Conference of Governmental Industrial Hygienists (ACGIH) has designated this chemical as not classifiable as a human carcinogen (A4).

The US National Toxicology Program (NTP) has listed this chemical as reasonably anticipated to be a human carcinogen.

Teratogenicity and Embryotoxicity:
Limited human information is available. Transplacental poisoning has occurred.(10) In animal studies, reproductive effects occurred only at doses causing maternal toxicity.

Reproductive Toxicity:
Information not available

No human information. No evidence of mutagenicity was observed in studies on animal cells or bacteria.

Toxicologically Synergistic Materials:
Information not available

Potential for Accumulation:
Naphthalene is broken down and excreted in urine and bile. Urinary excretion of mercapturic acids is considered an indicator of human exposure.(11)


This chemical is a carcinogen. Take proper precautions to ensure your own safety before attempting rescue (e.g. wear appropriate protective equipment). Remove source of contamination or move victim to fresh air. Obtain medical attention immediately.

Skin Contact:
Avoid direct contact. Wear chemical protective clothing, if necessary. Remove contaminated clothing, shoes and leather goods (e.g., watchbands, belts). Quickly blot or brush away excess chemical. Wash gently and thoroughly with water and non-abrasive soap for at least 5 minutes or until the chemical is removed. If irritation persists, repeat flushing. Obtain medical advice immediately. Discard contaminated clothing, shoes and leather goods.

Eye Contact:
Avoid direct contact. Wear chemical protective gloves, if necessary. Quickly and gently blot or brush away excess chemical. Do not allow victim to rub eye(s). Let the eye(s) water naturally for a few minutes. Have victim look right and left, and then up and down. If particle/dust does not dislodge, flush with lukewarm, gently flowing water for 5 minutes or until particle/dust is removed, while holding eyelid(s) open. If irritation persists, obtain medical attention. DO NOT attempt to manually remove anything stuck to eye(s).

NEVER give anything by mouth if victim is rapidly losing consciousness, is unconscious or convulsing. Have victim rinse mouth thoroughly with water. DO NOT INDUCE VOMITING. Have victim drink 240 to 300 mL (8 to 10 oz.) of water. If vomiting occurs naturally, rinse mouth and repeat administration of water. If breathing has stopped, trained personnel should begin artificial respiration or, if the heart has stopped, cardiopulmonary resuscitation (CPR) immediately. Obtain medical attention immediately.

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.
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:
79 deg C (174 deg F) (closed cup) (17)

Lower Flammable (Explosive) Limit (LFL/LEL):
0.9% by volume (17)

Upper Flammable (Explosive) Limit (UFL/UEL):
5.9% by volume (17)

Autoignition (Ignition) Temperature:
526 deg C (979 deg F) (17)

Sensitivity to Mechanical Impact:
Probably not sensitive. Normally stable material.

Sensitivity to Static Charge:
Under certain conditions, a dust cloud of this material can explode when ignited by a spark or flame. Explosions of naphthalene dusts have occurred in industry.(15)

Combustion and Thermal Decomposition Products:
Products of partial combustion may be irritating and toxic.

Fire Hazard Summary:
Flammable, volatile solid that gives off flammable vapours when heated. Under certain conditions, a dust cloud of this material can explode when ignited by a spark or flame. Important factors to be considered when evaluating explosivity hazards include particle size and shape, the nature of any impurities, dust concentration, humidity, and extent of containment. MINIMUM IGNITION TEMPERATURE: 575 deg C (1037 deg F).(18) MAXIMUM EXPLOSION PRESSURE: 87 psi.(18)

Extinguishing Media:
SMALL FIRES: Carbon dioxide, dry chemical powder, foam, water spray or fog. LARGE FIRES: Water spray, fog, foam. (DOT recommendations for naphthalene).

Fire Fighting Instructions:
Water spray may be used to extinguish fires because naphthalene can be cooled below its flashpoint. Use water spray to keep fire-exposed containers cool. Massive fires may require the use of unmanned hose holder or monitors. If this is impossible, it may be necessary to withdraw and let fire burn. Molten naphthalene at high temperature may react with foam or direct water spray with excessive foaming. Cooling action of water spray and extinguishing other sources of ignition and heat sources may alleviate this problem. Naphthalene is hazardous to health, but areas may be entered freely if a full- face mask, self-contained breathing apparatus that provides complete eye protection is worn.


NFPA - Health: 2 - Intense or continued (but not chronic) exposure could cause temporary incapacitation or possible residual injury.
NFPA - Flammability: 2 - Must be moderately heated or exposed to relatively high ambient temperatures before ignition can occur.
NFPA - Instability: 0 - Normally stable, even under fire conditions, and not reactive with water.


Molecular Weight: 128.18

Conversion Factor:
1 ppm = 5 mg/m3; 1 mg/m3 = 0.2 ppm at 25 deg C

Physical State: Solid
Melting Point: 80.2 deg C (176.5 deg F)
Boiling Point: 218 deg C (424 deg F)
Relative Density (Specific Gravity): 1.162 (water = 1)
Solubility in Water: Almost insoluble (3 mg/100 mL at 20 deg C)
Solubility in Other Liquids: Very soluble in benzene and chloroform; soluble in a wide variety of aromatic solvents, ethers, alcohols, carbon disulphide and chlorinated hydrocarbons.
Coefficient of Oil/Water Distribution (Partition Coefficient): Log P(oct) = 3.01 - 3.59
pH Value: Not applicable
Vapour Density: 4.42 (air = 1)
Vapour Pressure: 0.054 mm Hg at 20 deg C
Saturation Vapour Concentration: 100 ppm at 25 deg C
Evaporation Rate: Not available
Critical Temperature: 475.2 deg C (855.4 deg F)


Normally stable

Hazardous Polymerization:
Does not polymerize

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., chromic anhydride, fuming nitric acid, perchloric acid) - can react violently

STRONG ACIDS (e.g., sulfuric acid) - react non-violently (4)

Hazardous Decomposition Products:

Conditions to Avoid:
Static charge, sparks

Corrosivity to Metals:
Not corrosive


LD50 (oral, mouse): 533 mg/kg (male); 710 mg/kg (female) (1)
LD50 (oral, rat): 1780 mg/kg (2)

Eye Irritation:

100 mg administered in Standard Draize test resulted in "mild" irritation in rabbits.(3)

Skin Irritation:

495 mg administered in Open Draize test resulted in mild irritation in rabbits.(3)

Effects of Short-Term (Acute) Exposure:

Cataract formation has been reported in rabbits given naphthalene at doses of 1000 mg/kg/day. In one study, cataracts appeared after 1 day; in another study at 2 weeks.

Effects of Long-Term (Chronic) Exposure:

A 90-day oral gavage study, at doses of 5.3, 53 and 133 mg/kg/day showed negative results with respect to mortality and reduced body weight. In a related 14-day study, at doses of 27, 53 and 267 mg/kg, both sexes exhibited 5 to 10% mortality and reduced body weight only at the highest dose.(1,16) In neither study did mice develop hemolytic anemia.(16) However, hemolytic anemia was reported in dogs (one dog receiving a single dose of 1525 mg/kg/day and another receiving 263 mg/kg/day for 7 days.(16) Male rats tolerated daily doses of 1000 mg/kg without lethality, even after 18 days. Rabbits tolerated 1000 mg/kg twice a week for 2 weeks without lethality. In an increasing dosage study, male rats were treated with naphthalene beginning with 100 mg/kg/day and raised to 750 mg/kg/day within 6 weeks for a total of 9 weeks. No respiratory toxicity or fatalities occurred at 750 mg/kg/day. No increase in deaths occurred in rats given naphthalene at doses of 41/kg/day for 2 years.

IARC has concluded there is sufficient evidence for the carcinogenicity of naphthalene in experimental animals.
Exposure of rats by inhalation has been associated with cancer of the olfactory epithelium and nasal respiratory epithelium. These tumours are considered rare in unexposed rats. In addition, a screening assay using only female mice exposed by inhalation showed an increase in lung tumours and an inhalation study with mice showed bronchiolo-alveolar tumours in female mice. An apparent increase in the incidence of bronchiolo-alveolar tumours in male mice was not statistically significant.(21) Naphthalene did not cause tumours in rats fed diets containing 10-20 mg naphthalene (total dose 10 g). In the same study, no tumours were observed in rats receiving intraperitoneal and subcutaneous doses of 20 mg naphthalene weekly for 40 weeks.(13)

Teratogenicity, Embryotoxicity and/or Fetotoxicity:
Large oral doses (2400 mg/kg total) given to mice on days 7-14 of pregnancy caused reduced live births and reduced survival. Doses were maternally toxic. Very large doses (5925 mg/kg total) given to rats intraperitoneally over days 1-15 of pregnancy caused structural abnormalities.(3) This route of exposure is not relevant to occupational situations.


Selected Bibliography:
(1) Shopp, G.M.K.L., et al. Naphthalene toxicity in CD-1 Mice: General toxicology and immunotoxicology. (Abstract). Fundamental and Applied Toxicology. Vol. 4, no. 3, part 1 (1984).
(2) Naphthalene. Industrial Bio-Test Laboratories (Data sheet no. 16-4/70). Northbrook, 1970
(3) RTECS record for naphthalene. Last updated 9201
(4) Kirk-Othmer encyclopedia of chemical technology. Vol. 15. 3rd ed. John Wiley & Sons, 1981. p. 698-719
(5) Freeman, A.E., et al Transformation of cell cultures as an indication of the carcinogenic potential of chemicals. Journal of the National Cancer Institute. Vol. 51 (1973). p. 799
(6) Rhim, J.S., et al Evaluation of an in vitro assay system for carcinogens based on prior infection of rodent cells with nontransforming RNA tumor virus. Journal of the National Cancer Institute. Vol. 52 (1974). p. 1167
(7) Documentation of the threshold limit values and biological exposure indices. 5th ed. ACGIH, 1986. p. 293
(8) Grant, W.M. Toxicology of the eye. 3rd ed. Charles C. Thomas, 1986. p. 650-653
(9) Naphthalene (Hygienic guide series). American Industrial Hygiene Association, 1978
(10) Gosselin, R.E., et al. Clinical toxicology of commercial products. 5th ed. Williams and Wilkins, 1984. p. III-309
(11) Summer, K.H., et al. Urinary excretion of mercapturic acids in chimpanzees and rats. Toxicology and Applied Pharmacology. Vol. 50, no. 2 (1979). p. 207-212
(12) NIOSH pocket guide to chemical hazards. NIOSH, June 1994. p. 220-221
(13) Schmahl, D. The testing of naphthalene and anthracene for a carcinogenic effect of rats. (Abstract). Zeitschrift fuer Krebsforschung. Vol. 60 (1955)
(14) HSDB record for naphthalene. Last revision date 91/09/12
(15) Field, P. Explosibility assessment of industrial powders and dusts. Her Majesty's Stationery Office, 1983
(16) Toxicological profile for naphthalene and 2-methylnaphthalene. US Department of Health and Human Services, Dec. 1990
(17) Fire protection guide to hazardous materials. 13th ed. Edited by A.B. Spencer, et al. National Fire Protection Association, 2002. NFPA 325; NFPA 49
(18) Grossel, S.S. Safety considerations in conveying bulk solids and powders. Journal of Loss Prevention Process Industries. Vol. 1 (Apr. 1988). p. 62-74
(19) Forsberg, K., et al. Quick selection guide to chemical protective clothing. 4th ed. Van Nostrand Reinhold, 2002
(20) European Communities (EC). Commission Directive 2004/73/EC. Apr. 29, 2004
(21) International Agency for Research on Cancer (IARC). Naphthalene. In: IARC monographs on the evaluation of carcinogenic risks to humans. Vol. 82. Some traditional herbal medicines, some mycotoxins, naphthalene and styrene. World Health Organization, 2002. p. 367-435
(22) Report on Carcinogens. 11th ed. US Department of Health and Human Services, Public Health Service, National Toxicology Program

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: 1992-11-06

Revision Indicators:
Trans PEL-TWA 1993-04-01
Handling 1994-01-01
TDG 1994-03-01
Sampling 1996-01-01
EU number 1996-01-01
Respiratory guidelines 1996-01-01
TLV-TWA 1996-09-01
TLV comments 1996-09-01
TLV-STEL 1996-09-01
US transport 1998-02-01
Resistance of materials 1998-05-01
TDG 2002-06-03
Toxicological info 2003-07-08
WHMIS detailed classification 2003-07-08
WHMIS proposed classification 2003-07-08
WHMIS disclosure list 2003-07-08
WHMIS health effects 2003-07-08
Emergency overview 2003-07-08
Long-term exposure 2003-07-08
Short-term skin contact 2003-07-08
First aid inhalation 2003-07-08
First aid skin 2003-07-08
First aid eye 2003-07-08
Handling 2003-07-08
Storage 2003-07-08
PEL transitional comments 2003-11-06
PEL-TWA final 2003-11-06
PEL-STEL final 2003-11-06
TLV definitions 2004-01-01
TLV-TWA 2004-01-01
TLV-STEL 2004-01-01
EU classification 2004-11-29
EU risks 2004-11-29
EU safety 2004-12-28
Carcinogenicity 2005-02-02
Bibliography 2005-02-02

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