CAREX Canada

Full Profile

CAS No. 91-20-3

Photo Credit: Wikimedia Commons^[1]

IARC Monograph Vol. 82, 2002 (Group 2B)

General Information

Naphthalene, a polycyclic aromatic hydrocarbon, may exist as white crystalline plates, balls or powder, and has a distinctive mothball odour.^[2] Naphthalene occurs naturally in fossil fuels and is a combustion product of organic material. It has several industrial uses, primarily as a chemical intermediate.^[2]

Naphthalene may also be referred to as “naphthalin” or “white tar”.^[2] There are numerous other synonyms and product names; see HSDB for more information.^[3]

Other substances related to naphthalene which are being considered by CAREX Canada are polycyclic aromatic hydrocarbons (PAHs), coal-tar and coal-tar pitches, and creosote; the Carcinogen Profiles for these substances should be consulted for further information.

In 2002, IARC classified naphthalene as Group 2B, possibly carcinogenic to humans.^[2] Epidemiological studies available were not adequate to provide evidence of carcinogenicity in humans, however animal studies showed increased rates of nasal/olfactory and respiratory tumours in rats and mice exposed to naphthalene.^[2,4]

Other adverse health effects which may result from acute exposure to naphthalene include hemolytic anemia, liver and neurological damage, gastrointestinal upset, respiratory effects and dermatitis.^[3,5] Chronic exposure may cause neuropathy, retinal damage, renal failure and liver necrosis.^[3]

Naphthalene has been ranked by CAREX Canada as Group A (immediate high priority) for occupational settings and as Group B (possible high priority) for environmental settings. Prioritization was based on the carcinogenicity and other toxic properties of the substance, the prevalence of exposure in Canada, and the feasibility of assessing exposure.

Regulations and Guidelines

Occupational Exposure Limits (OEL)

Canadian Jurisdictions	OEL (mg/m³)
Canada Labour Code	10 [sk] 15 [stel]
BC, AB, SK, MB, NL, PE, NB, NS	10 [sk] 15 [stel]
ON, QC, YT, NT, NU	10 15 [stel]
Other Jurisdictions	OEL (mg/m³)
ACGIH 20010 TLV	10 [sk] 15 [stel]

mg/m³ = milligrams per cubic meter

sk = easily absorbed through the skin

stel = short term exposure limit (15 min. maximum)

TLV = threshold limit value

Environmental Guidelines

Jurisdiction	Limit	Year
Health Canada Cosmetics Ingredient Hotlist	Prohibited	2010^[23]
Ontario Ministry of the Environment	POI: 36 μg/m³ AAQCs:22.5 μg/m³	2008^[10]

POI = Point of impingement (half hour)

AAQCs = Ambient air quality criteria (24 hour)

Naphthalene is not included in other Canadian environmental guidelines reviewed.^[8,9,24]

Canadian Agencies/Organizations

Agency	Designation/Position	Year
Health Canada	DSL - high priority substance with the greatest potential for exposure	2006^[11]
PMRA List of Formulants	List 2: potentially toxic formulant	2010^[30]
CEPA	Schedule 1	2011^[12]
CMP Challenge	Batch 1 [Health]	2007^[14]

DSL = Domestic substance list

CEPA = Canadian Environmental Protection Act

CMP = Chemical Management Plan

Main Uses

Naphthalene is primarily used in the production of phthalic anhydride, which is an intermediate chemical in the manufacturing of polyvinyl chloride plasticizers, pharmaceuticals, insect repellents, and other materials.^[2,4] Naphthalene also acts as a solvent and is used in the production of automobile paint, driveway sealants, various chemicals in the dye and synthetic leather tanning industries, surfactants, veterinary medicines, lubricants, motor fuels and in toilet deodorizers.^[2,4] Historically, naphthalene was widely used as a moth and insect repellent. However, use of naphthalene as a moth-repellent and insecticide has been decreasing since the introduction of chlorinated compounds.^[2] Currently, out of five products containing naphthalene as the active ingredient registered with the PMRA for use in Canada, four of which are moth repellents.^[15] Naphthalene may also be found in commercially available consumer products such as paints, stains and coatings.^[14] In Canada, naphthalene is also used as an oilfield chemical, solvent, refinery cleaner, fuel additive and feedstock in the petroleum industry.^[14]

Canadian Production and Trade

Naphthalene is produced in Canada and is also imported into the country.^[16] Naphthalene is primarily produced from coal tar; it can also be produced from petroleum.^[2] Coal tar and petroleum contain up to 11% and 1.3% of naphthalene, respectively.^[2]

In 2000, there were 13 manufacturers and 18 importers of naphthalene listed in Canada.^[14] In that year, total of over 52,000 tonnes of naphthalene were produced, and over 150,000 tonnes were imported.^[14]

Production and Trade

Activity	Quantity	Year
Canadian production	52,000 t	2000^[14]
Export: Mainly to the US	12,330 t of 'naphthalene'	2010^[17]
Import: Mainly from Japan and the US	7,480 t of 'naphthalene'	2010^[17]

t = tonne

Occupational Exposures

Inhalation and dermal contact are the most important routes of occupational exposure.^[2,18] Industries with exposures to naphthalene include wood preservation (creosote impregnation), coal tar and coke industries, asphalt industries (paving and roofing), petroleum refining, and aluminum reduction facilities.^[2] Workers may also encounter naphthalene during the production of mothballs, grinding wheels, and when exposed to petroleum products, especially jet fuels.^[18,19]

Environmental Exposures

The general population’s major source of exposure to naphthalene is indoor air.^[14] Exposure in indoor air occurs mainly through inhalation of naphthalene-containing moth repellents and tobacco smoke.^[2] Other sources of inhalation exposure include: driveway sealants, fuel additives, paints, epoxies, some hydrocarbon solvents, and pesticides.^[13,20] Additional ambient air sources include combustion of organic material, coal and oil, forest fires, and power plants.^[5] In 2005, 34 of 73 facilities using naphthalene reported releases into the environment. The top 4 emitters were located in Ontario.^[14]

Dermal exposures from products treated with mothballs (blankets, clothing etc.) can be significant.^[5] The concentration of naphthalene in consumer goods can range up to 13% (excluding moth balls).^[14] Ingestion exposure to naphthalene is also possible through contaminated drinking water and food.^[5] Although naphthalene is not permitted as a food additive in Canada, it is used as a solvent in coatings for food packaging.^[14] Small amounts of naphthalene used in food packaging may migrate into food.

Naphthalene levels in water, soil and sediment tend to be low except in close proximity to point sources, where there is potential for contamination.^[5] Naphthalene evaporates and degrades quickly, and is not expected to bioaccumulate.^[5]

Searches of environmental and consumer product databases yielded the following results on current potential for exposure to naphthalene in Canada:

NPRI and US Household Products Database

NPRI 2009^[21]
Search Term: naphthalene
Category	Quantity	Industry
Released into Environment	70 t	Basic chemical manufacturing, sawmill and oil refining (79 companies in total)
Disposed of	221 t
Sent to off-site recycling	84 t