INDUSTRIAL CHEMICALS – POSSIBLE CARCINOGEN (IARC 2B)
Naphthalene, a polycyclic aromatic hydrocarbon, may exist as white crystalline plates, balls, or powder, and has a distinctive mothball odour. Naphthalene occurs naturally in fossil fuels and is a combustion product of organic material. It has several industrial uses, primarily as a chemical intermediate.
Naphthalene may also be referred to as naphthalin or white tar. There are numerous other synonyms and product names; see Hazardous Substances Data Bank (HSDB) for more information.
Other substances related to naphthalene that are considered by CAREX Canada include polycyclic aromatic hydrocarbons (PAHs), coal-tar and coal-tar pitches, and creosotes; please consult these profiles for further information.
In 2002, the International Agency for Research on Cancer (IARC) classified naphthalene as Group 2B, possibly carcinogenic to humans. The 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.[1,3]
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.[2,4] Chronic high exposure may cause neuropathy, retinal damage, renal failure, and liver necrosis.
Regulations and Guidelines
Occupational exposure limits (OEL) [5,6,7,8,9,10,11,12,13,14,15,16,17,18,19]
|Canadian Jurisdictions||OEL (ppm)|
|Canada Labour Code||10 [sk]|
|MB, NL, NS, PE,||10 [sk]|
|AB, BC, NB, NT, NU, ON, SK||10 [sk]
|Other Jurisdictions||OEL (ppm)|
|ACGIH 2020 TLV||10 [sk]|
ppm = parts per million
sk = easily absorbed through the skin
stel = short term exposure limit (15 min. maximum)
ACGIH = American Conference of Governmental Industrial Hygienists
TLV = threshold limit value
Environmental guidelines and standards*
|Health Canada Cosmetics Ingredient Hotlist||Prohibited||2010|
|Residential Indoor Air Quality Guidelines||24 hour limit: 10 μg/m3||2013|
|Ontario Ambient Air Quality Criteria||10 minute: 50 µg/m3
24 hour: 22.5 µg/m3
|Quebec’s Clean Air Regulation||4 minute limit: 200 µg/m3
1 year limit: 3 µg/m3; Prohibited discharge into the air if the concentration of naphthalene exceeds the standard
|Alberta Ambient Air Quality Objectives and Guidelines||Annual: 3 μg/m3||2016|
|BC’s Contaminated Sites Regulation, BC Reg 375/96||Sets soil standards for the protection of human health:
Agricultural and low density residential sites: 850 μg/g
Urban park and high density residential sites: 1,500 μg/g
Commercial sites: 5,000 μg/g
Industrial sites: 150,000 μg/g
Drinking water standards: 80 μg/L
Sets vapour standards for the protection of human health:
*Standards are legislated and legally enforceable, while guidelines (including Ontario ambient air quality criteria) describe concentrations of contaminants in the environment (e.g. air, water) that are protective against adverse health, environmental, or aesthetic (e.g. odour) effects
µg/m3 = micrograms per cubic meter
µg/g = micrograms per gram
|Health Canada||DSL – high priority substance with the greatest potential for exposure||2006|
|PMRA List of Formulants||List 4B: List 4B contains formulants, some of which may be toxic, for which there are sufficient data to reasonably conclude that the specific use pattern of the pest control product will not adversely affect public health and the environment.||2020|
|Challenge to industry||Batch 1 [Health]||2007|
|National Classification System for Contaminated Sites||Rank = “Medium hazard”||2008|
|Environment Canada’s National Pollutant Release Inventory||Reportable to NPRI if manufactured, processed, or otherwise used at quantities greater than: 10 tonnes||2016|
DSL = domestic substance list
PMRA = Pest Management Regulatory Agency
CEPA = Canadian Environmental Protection Act
CMP = Chemical Management Plan
Naphthalene was not included in other Canadian government guidelines, standards, or chemical listings reviewed.
Naphthalene is primarily used to produce phthalic anhydride, which is an intermediate chemical in the manufacture of polyvinyl chloride plasticizers, pharmaceuticals, insect repellents, and other materials.[1,3] Naphthalene also acts as a solvent and is used to produce automobile paint, driveway sealants, various chemicals in the dye and synthetic leather tanning industries, surfactants, veterinary medicines, lubricants, motor fuels, and toilet deodorizers.[1,3]
Until recently, naphthalene was widely used as a moth and insect repellent. This use has been decreasing since chlorinated compounds were introduced. As of 2016, four products containing naphthalene as the active ingredient were registered with the Pest Management Regulatory Agency (PMRA) for use in Canada. Of these, three are moth repellents. Naphthalene may also be found in commercially available consumer products such as paints, stains, and coatings. In Canada, naphthalene is also used as an oilfield chemical, solvent, refinery cleaner, fuel additive, and feedstock in the petroleum industry.
Canadian Production and Trade
Naphthalene is primarily produced from coal tar, but can also be produced from petroleum. Coal tar and petroleum contain up to 11% and 1.3% of naphthalene, respectively.
No recent data on naphthalene manufacture in Canada was found.
Production and Trade
|Export:||5,654 t of ‘naphthalene containing > 50% of naphthalene (excluding chemically defined)’||2021|
|Import:||342 t of ‘naphthalene containing > 50% of naphthalene (excluding chemically defined)’||2021|
t = tonne
Environmental Exposures Overview
The general population’s major source of exposure to naphthalene is indoor air. Exposure in indoor air occurs mainly by inhaling naphthalene-containing moth repellents and tobacco smoke.[1,35] Other sources of inhalation exposure include: driveway sealants, fuel additives, paints, epoxies, some hydrocarbon solvents, attached garages, and pesticides.[34,35,36,37] Systematic indoor air sampling of naphthalene has not been conducted in Canada, but numerous studies have evaluated levels of naphthalene in indoor air in specific Canadian cities.[38,39] Additional sources of naphthalene in ambient air include combusting organic material, coal and oil, forest fires, wood preserving operations, asphalt industries, and power plants.[4,40] Air emissions account for 92% of total naphthalene released to the environment.
Dermal exposures from products treated with mothballs (blankets, clothing etc.) can be significant. Ingestion exposure to naphthalene is also possible through contaminated drinking water and food. Although naphthalene is not permitted as a food additive in Canada, as of 2008 it was used as a solvent in coatings for food packaging. 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. Naphthalene evaporates and degrades quickly, and is not expected to bioaccumulate.
Searches of Environment Canada’s National Pollutant Release Inventory (NPRI) and the US Consumer Product Information Database yielded the following results on current potential for exposure to naphthalene in Canada:
NPRI and US Consumer Product Information Database
|Search Term: ‘naphthalene’|
|Released into Environment||60 t||Oil and gas extraction, petroleum and coal product manufacturing, pulp and paper mills, chemical manufacturing, iron and steel mills and manufacturing (90 facilities)|
|Disposed of||137 t|
|Sent to off-site recycling||654 t|
t = tonne
|US Consumer Products 2016|
|Search Term: ‘naphthalene’|
|103||Gasoline additives and fuel injector cleaners, ceramic paints, pesticides/repellents, and oil products|
Occupational Exposures Overview
Inhalation and dermal contact are the most important routes of occupational exposure to naphthalene.[1,43]
CAREX Canada estimates that approximately 6,700 Canadians are exposed to naphthalene in their workplaces. The largest industrial groups exposed are petroleum and coal products manufacturing, alumina and aluminum production and processing, and sawmills and wood preservation, foundries, and basic chemical manufacturing. Other industries that may be exposed to naphthalene include coal tar and coke industries, as well as construction industries (paving and roofing).
The largest occupational groups exposed to naphthalene are machine operators in mineral and metal processing, central control and process operators in petroleum, gas and chemical processing, material handlers, and labourers in mineral and metal processing. Other workers may be exposed while producing mothballs, grinding wheels, and working with petroleum products, especially jet fuels.[43,44]
For more information, see the occupational exposure estimate for naphthalene.
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