Fact sheet: Naphthalene

General information

CAS number

91-20-3

Molecular formula

C₁₀H₈

Formula weight

128.2 g/mol

Family

Polycyclic aromatic hydrocarbons (PAH)

Properties (at room temperature where applicable)

Environmental behaviour

At 20 ⁰C, naphthalene is a solid with low volatility. Characterized by its low solubility, it will moderately volatilize once dissolved and adsorbs strongly to organic matter. When present in soil, this compound will undergo light volatilization and solubilize slowly. Once dissolved, it will either enter into the groundwater table or migrate towards a waterway, where it will be diluted before partially volatilizing. Fragments of naphthalene can also be carried into a waterway where they will deposit at the bottom and slowly dissolve. Once the source has been removed, the adsorbed naphthalene will take a long some time to disappear, being released in its gaseous or dissolved forms. The resulting plumes (gaseous or dissolved) will be relatively small in size.

Health and safety

Naphthalene should be handled with care, as it is toxic and flammable.

Principal resources

Naphthalene is a polycyclic aromatic hydrocarbon (PAH). PAHs are a group of organic compounds that contain two or more benzene rings in their structure. There are more than 100 different PAHs that generally occur as complex mixtures (example, combustion by-products such as soot). Incomplete combustion of fuels in engines, during coal coking, or when wood is burning (forest fires, wood stoves) produces PAHs. PAHs are also constituents of petroleum and coal, and they are more present in some of their derivatives like tars and asphalt. The wood preservative industry (example, creosote), aluminum smelters using Soderberg electrodes, and hazardous waste disposal sites are further contributors of anthropogenic PAHs to the environment.

Naphthalene is produced industrially in large amounts from either coal tar (which contains approximately 10% naphthalene) or petroleum hydrocarbons. The principal use of naphthalene (over 60%) is in the production of phthalic anhydride, which is an intermediate in the production of phthalate plasticizers (used in different polymers and resins like polyvinyl chloride, polyurethane, and rubbers), insect repellents, pharmaceuticals and other materials. Naphthalene has also been used in the production of surfactants (naphthalene sulfonates and derivatives used in paint, dye, and paper-coating formulations), naphthalene derivatives (example, decalin), some insecticides, moth repellents, explosives, fuel additives, corrosion inhibitors, and driveway sealants formulations. Naphthalene is also found mixed with other PAHs in commercial products like coal tar, coal tar pitch, creosote and bitumen and asphalt. Naphthalene is no longer used directly in tanneries, in the textile industry, or in the production of beta-naphthol and toilet bowl deodorizers.

References

Agency for Toxic Substances and Disease Registry (ATSDR). 2005. Toxicological Profile for Naphthalene, 1-Methylnaphthalene, and 2-Methylnaphthalene. U.S. Department of Health and Human Services, Public Health Service, Georgia, USA. (Viewed December 2013)

Canadian Council of Ministers of the Environment. 1999. Canadian Water Quality Guidelines for the Protection of Aquatic Life: Polycyclic Aromatic Hydrocarbons (PAHs). In: Canadian Environmental Quality Guidelines. Canadian Council of Ministers of the Environment, Manitoba, Canada. (Viewed December 2013)

Montgomery, John H. 2007. Groundwater Chemicals, Desk Reference, Fourth Edition, CRC Press, Taylor and Francis Group, Florida, USA.

National Toxicology Program. 2005. Report on Carcinogens, Twelfth Edition: Substance Profile of Polycyclic Aromatic Hydrocarbons. U.S. Department of Health and Human Services, Public Health Services, USA.(PDF, 142KB) (Viewed December 2013)