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DESIGNATIONS
CAS No.: 91-20-3
Registry name: Naphthalene
Chemical name: Naphthalene
Synonyms, Trade names: Antimite, Tar camphor
Chemical name (German): Naphthalin
Chemical name (French): Naphthalène
Appearance: white crystalline solid
BASIC CHEMICAL AND PHYSICAL DATA
| Empirical formula: | C10H8 | ||
| Rel. molecular mass: | 128.17 g | ||
| Density: | 1.14 g/cm3 | ||
| Relative gas density: | 4.42 | ||
| Boiling point: | 218°C | ||
| Melting point: | 80°C | ||
| Vapour pressure: | 0.04 hPa | ||
| Flash point: | 80°C | ||
| Ignition temperature: | 540°C | ||
| Explosion limits: | 0.9-5.9 % by vol. | ||
| Solvolysis/solubility: | in water: very slightly soluble | 30 mg/l | |
| soluble in | alcohol | 77.4-98 g/l | |
| benzene | 1,130 g/l | ||
| quinoline | 30.2 g/l | ||
| toluene | 910 g/l | ||
| xylene | 783 g/l | ||
| Conversion factors: | 1 ppm = 5.33 mg/m3 1 mg/m3 = 0.19 ppm |
||
ORIGIN AND USE
Usage:
Naphthalene is used as an intermediate in the manufacture of
dyes, phthalic anhydride (production of PVC plasticisers),
tanning agents, substances used for concrete, wetting agents for
the textile industry and solvent components for pesticides (moth
repellents).
Origin/derivation:
The raw material source in Germany is coal tar which contains
some 10% naphthalene. As coke production is on the decline,
increasing use is made of petroleum-based raw materials (gasoline
pyrolysis, residual oils following pyrolysis); manufacture by
means of distillation and fractioning. The naphthalene content of
the technical product is at least 95% while the remainder is made
up of impurities such as benzo(b)thiophene (thionaphthene) or, in
petroleum-based naphthalenes, of methylindenes only.
Production figures:
World production of naphthalene in 1987
| Western Europe | 250,000 t |
| Eastern Europe | 200,000 t |
| Japan | 200,000 t |
| USA | 125,000 t |
| World | 1,000,000 t |
(figures from ULLMANN, 1991)
Toxicity
| Mammals: | ||
| Rat: | LD50 1,110-9,430 mg/kg, oral | acc. BUA, 1989 |
| Rat: | LD50 2,200 mg/kg, oral (male) | acc. BUA, 1989 |
| Rat: | LD50 2,400 mg/kg, oral (female) | acc. BUA, 1989 |
| Rat: | LD50 > 2,500 mg/kg, dermal (male,female) | acc. BUA, 1989 |
| Rat: | LD50 > 500 mg/m3, inhalation (8 h) | acc. BUA, 1989 |
| Mouse: | LD50 350-710 mg/kg, oral (female) | acc. BUA, 1989 |
| Mouse: | LD50 533 mg/kg, oral (male) | acc. BUA, 1989 |
| Mouse: | LD50 969-5,100 mg/kg, subcutaneous | acc. BUA, 1989 |
| Aquatic organisms: | ||
| American minnow: | LC50 1.3-6.9 mg/l (96 h) | acc. BUA, 1989 |
| American minnow: | LC50 5.95-6.77 mg/l (48 h) | acc. BUA, 1989 |
| Micropterus salmondes: | LC50 0.31-9.7 mg/l (7 d) | acc. BUA, 1989 |
| Rainbow trout: | LC50 0.1-0.14 mg/l (96 h) | acc. BUA, 1989 |
| Water flea: | LC50 1.79-24.1 mg/l (48 h) | acc. BUA, 1989 |
Characteristic effects:
Humans/mammals: Naphthalene is absorbed orally, dermally or by way of inhalation. The toxic effect is generally slight. Irritation of the mucous membranes and skin is extremely rare. The absorption of a large dose causes haemolytic anaemia, the formation of cataracts and sensitisation. Infants and foetuses are particularly at risk. There have also been cases of allergic reactions in humans.
The toxicity of chlorinated naphthalenes is considerably higher (refer to the "chloronaphthalene" information sheet).
ENVIRONMENTAL BEHAVIOUR
Water:
Naphthalene dissolves only very slightly in water and sinks as a
solid. Because of its toxic effect on aquatic organisms even at
low concentrations, naphthalene is considered as a substance
hazardous to water (In Germany: Water Hazard Class 2).
Air:
Naphthalene is produced when organic material is incompletely
combusted.
Half-life:
The half-life in the atmosphere is estimated at 7 to 24 hours
(acc. BUA, 1989).
Degradation, decomposition products:
Naphthalene is degraded microbially or photochemically;
mineralisation has however not been substantiated to date under
anaerobic conditions. The primary metabolite in the organism is
naphthalene-1,2-oxide which is converted to form other compounds.
Naphthalene is oxidised in air to form alcohols (naphthols),
aldehydes and carboxylic acids.
Food chain:
There is little bioaccumulation by way of food chains.
ENVIRONMENTAL STANDARDS
| Medium/ acceptor | Sector | Country/ organ. | Status | Value | Cat. | Remarks | Source |
| Water: | Groundw | Nl | G |
0.1 µg/l | Reference | acc. TERRA TECH 6/94 | |
| Groundw | NL | L |
70 µg/l | Intervention | acc. TERRA TECH 6/94 | ||
| Soil: | NL | G |
1 mg/kg | Reference, Sum of 10 PAHs |
acc. TERRA TECH 6/94 | ||
| NL | L |
40 mg/kg | Intervention, Sum of 10 PAHs |
acc. TERRA TECH 6/94 | |||
| Air: | D | L |
2.5 mg/m3 | MIK | Long-time value | acc. BAUM, 1988 | |
| D | L |
7.5 mg/m3 | MIK | Short-time value | acc. BAUM, 1988 | ||
| Emiss. | D | L |
0.1 g/m3 | mass flow > 2 g/h | acc. TA Luft, 1986 | ||
| DDR | (L) |
3 mg/m3 | Short-time value | acc. HORN, 1989 | |||
| DDR | (L) |
1 mg/m3 | Long-time value | acc. HORN, 1989 | |||
| Workp | D | L |
50 mg/m3 | MAK | DFG, 1989 | ||
| Workp | DDR | (L) |
50 mg/m3 | Short-time value | acc. HORN, 1989 | ||
| Workp | DDR | (L) |
20 mg/m3 | Long-time value | acc. HORN, 1989 | ||
| Workp | SU | (L) |
20 mg/m3 | PDK | acc. SORBE, 1989 | ||
| Workp | USA | (L) |
50 mg/m3 | TWA | ACGIH, 1986 | ||
| Workp | USA | (L) |
75 mg/m3 | STEL | ACGIH, 1986 |
Comparison/reference values
| Medium/origin | Country | Value | Source |
| Surface water: | |||
| Rhine (1987) | D | < 0.01-0.03 µg/l | |
| Lake Constance (summer, 1984) | D | 0.002-0.276 µg/l | acc. BUA, 1989 |
| acc. BUA, 1989 | |||
| Air: | |||
| Urban air (1977-1984) | D | 0.3-0.6 µg/m3 | |
| Kiel | D | 0.009 µg/m3 | acc. BUA, 1989 |
| Tübingen | D | 0.191-0.468 µg/m3 | acc. BUA, 1989 |
| Cigarette smoke (unfiltered) | 0.422 µg/cigarette (main stream) | acc. BUA, 1989 | |
| acc. BUA, 1989 | |||
Assessment/comments
Naphthalene has only a slight toxic effect, but can cause allergic reactions in humans (single case reports). Because of the emissions from motor-vehicle exhausts, the exposure is higher in urban areas. This can result in enhanced hypersensitivity to other irritants. There is no information available on carcinogenic or mutagenic potential, but the substance is a proven hazard to foetuses.