Naphthalene

Naphthalene is an organic compound with the formula C10H8. It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid, which is flammable with a characteristic odour that is detectable at concentrations as low as 0.08 ppm by mass. As an aromatic hydrocarbon, naphthalene’s structure consists of a fused pair of benzene rings. Naphthalene is the most abundant component of coal tar, which is the liquid by-product of the distillation of coal into coke for use as a smokeless fuel. In addition, naphthalene is produced upon the burning of organic material, such as fossil fuels, wood and tobacco, and is present in exhaust emissions and cigarette smoke. [fusion_builder_container hundred_percent=”yes” overflow=”visible”][fusion_builder_row][fusion_builder_column type=”1_1″ background_position=”left top” background_color=”” border_size=”” border_color=”” border_style=”solid” spacing=”yes” background_image=”” background_repeat=”no-repeat” padding=”” margin_top=”0px” margin_bottom=”0px” class=”” id=”” animation_type=”” animation_speed=”0.3″ animation_direction=”left” hide_on_mobile=”no” center_content=”no” min_height=”none”][1,2]

Uses [1]

Naphthalene is used mainly as a precursor in producing other chemicals. The single largest use of naphthalene is the industrial production of phthalic anhydride, although more phthalic anhydride is made from o-xylene. Other naphthalene-derived chemicals include alkyl naphthalene sulphonate surfactants, and the insecticide 1-naphthyl-N-methylcarbamate (carbaryl). Naphthalenes substituted with combinations of strongly electron-donating functional groups, such as alcohols and amines, and strongly electron-withdrawing groups, especially sulfonic acids, are intermediates in the preparation of many synthetic dyes. The hydrogenated naphthalenes tetrahydronaphthalene (tetralin) and decahydronaphthalene (decalin) are used as low-volatility solvents. In addition, naphthalene is used in the synthesis of 2-naphthol, a precursor for various dyestuffs, pigments, rubber processing chemicals and other miscellaneous chemicals and pharmaceuticals. Naphthalene sulfonic acids are used in the manufacture of naphthalene sulphonate polymer plasticisers (dispersants), which are used to produce concrete and plasterboard (wallboard or drywall). They are also used as dispersants in synthetic and natural rubbers, and as tanning agents (syntans) in leather industries, agricultural formulations (dispersants for pesticides), dyes and as a dispersant in lead–acid battery plates. Naphthalene sulphonate polymers are produced by reacting naphthalene with sulphuric acid and then polymerising with formaldehyde, followed by neutralisation with sodium hydroxide or calcium hydroxide. These products are commercially sold in solution (water) or dry powder form. Alkyl naphthalene sulphonates (ANS) are used in many industrial applications as nondetergent wetting agents that effectively disperse colloidal systems in aqueous media. The major commercial applications are in the agricultural chemical industry, which uses ANS for wettable powder and wettable granular (dry-flowable) formulations, and the textile and fabric industry, which utilises the wetting and defoaming properties of ANS for bleaching and dyeing operations. The most familiar use of naphthalene is as a household fumigant, such as in mothballs although 1,4-dichlorobenzene (or p-dichlorobenzene) is now more widely used. In a sealed container containing naphthalene pellets, naphthalene vapours build up to levels toxic to both the adult and larval forms of many moths that attack textiles. Other fumigant uses of naphthalene include use in soil as a fumigant pesticide, in attic spaces to repel animals and insects, and in museum storage-drawers and cupboards to protect the contents from attack by insect pests. Naphthalene is also used in pyrotechnic special effects such as the generation of black smoke and simulated explosions. In the past, naphthalene was administered orally to kill parasitic worms in livestock. Naphthalene and its alkyl homologues are the major constituents of creosote. Naphthalene is used in engineering to study heat transfer using mass sublimation.

Sources & Routes of Exposure [3]

Exposure to naphthalene can occur in the following ways:

  • Breathing low levels in outdoor air.
  • Breathing air contaminated from industrial discharges or smoke from burning wood, tobacco, or fossil fuels.
  • Using or making moth repellents, coal tar products, dyes or inks could expose you to these chemicals in the air.
  • Drinking water from contaminated wells.
  • Touching fabrics that are treated with moth repellents containing naphthalene.
  • Exposure to naphthalene, 1-methylnaphthalene and 2-methylnaphthalene from eating foods or drinking beverages is unlikely.

Health Risks [4]

Acute Effects

Acute exposure of humans to naphthalene by inhalation, ingestion, and dermal contact is associated with haemolytic anaemia, damage to the liver, and, in infants, neurological damage. Symptoms of acute exposure include headache, nausea, vomiting, diarrhoea, malaise, confusion, anaemia, jaundice, convulsions, and coma. Cataracts have been reported in humans acutely exposed to naphthalene by inhalation and ingestion.

Chronic Effects (Noncancer)

Chronic exposure of workers to naphthalene has been reported to cause cataracts and retinal haemorrhage. Chronic inflammation of the lung, chronic nasal inflammation, hyperplasia of the respiratory epithelium in the nose, and metaplasia of the olfactory epithelium were reported in mice chronically exposed to naphthalene via inhalation. Rats, rabbits, and mice chronically exposed to naphthalene via ingestion have developed cataracts and degeneration of the retina. EPA has calculated a Reference Concentration (RfC) of 0.003 milligrams per cubic meter (mg/m3) for naphthalene based on nasal effects in mice. The Reference Dose (RfD) for naphthalene is 0.02 milligrams per kilogram body weight per day (mg/kg/d) based on decreased body weight in male rats.

Reproductive/Developmental Effects

Haemolytic anaemia has been reported in infants born to mothers who “sniffed” and ingested naphthalene (as mothballs) during pregnancy. The mothers themselves were anaemic, but to a lesser extent than the infants.

Cancer Risk

Workers occupationally exposed to vapours of naphthalene and coal tar developed laryngeal carcinomas or neoplasms of the pylorus and caecum. However, this study is inadequate because there were no controls, exposure levels were not determined, and subjects were exposed to complex mixtures containing other demonstrated carcinogens. Di-, tri-, and tetramethyl naphthalene contaminants of coal tar were found to be carcinogenic when applied to the skin of mice, but naphthalene alone was not. EPA has classified naphthalene as a Group C, possible human carcinogen.

Safety [5]

First Aid Measures

  • Eye Contact: Check for and remove any contact lenses. Immediately flush eyes with running water for at least 15 minutes, keeping eyelids open. Cold water may be used. Do not use an eye ointment. Seek medical attention.
  • Skin Contact: After contact with skin, wash immediately with plenty of water. Gently and thoroughly wash the contaminated skin with running water and non-abrasive soap. Be particularly careful to clean folds, crevices, creases and groin. Cover the irritated skin with an emollient. If irritation persists, seek medical attention. Wash contaminated clothing before reusing.
  • Inhalation: Allow the victim to rest in a well ventilated area. Seek immediate medical attention.
  • Serious Inhalation: Evacuate the victim to a safe area as soon as possible. Loosen tight clothing such as a collar, tie, belt or waistband. If breathing is difficult, administer oxygen. If the victim is not breathing, perform mouth-to-mouth resuscitation. WARNING: It may be hazardous to the person providing aid to give mouth-to-mouth resuscitation when the inhaled material is toxic, infectious or corrosive. Seek immediate medical attention.
  • Ingestion: Do not induce vomiting. Examine the lips and mouth to ascertain whether the tissues are damaged, a possible indication that the toxic material was ingested; the absence of such signs, however, is not conclusive. Loosen tight clothing such as a collar, tie, belt or waistband. If the victim is not breathing, perform mouth-to-mouth resuscitation. Seek immediate medical attention.

Handling & Storage

  • Keep naphthalene locked up and away from heat. Flammable materials should be stored in a separate safety storage cabinet or room.
  • Keep away from sources of ignition.
  • Keep container tightly closed and dry.
  • Keep in a cool, well-ventilated place.
  • Ground all equipment containing material.
  • Do not ingest.
  • Do not breathe dust.
  • Avoid contact with eyes
  • Wear suitable protective clothing
  • In case of insufficient ventilation, wear suitable respiratory equipment
  • If ingested, seek medical advice immediately and show the container or the label.
  • Keep away from incompatibles such as oxidising agents.

Exposure Controls & Personal Protection

Engineering Controls

Use process enclosures, local exhaust ventilation, or other engineering controls to keep airborne levels below recommended exposure limits. If user operations generate dust, fume or mist, use ventilation to keep exposure to airborne contaminants below the exposure limit.

Personal Protection

Use the following personal protective equipment when handling naphthalene:

  • Splash goggles
  • Lab coat
  • Dust respirator (be sure to use an approved/certified respirator or equivalent)
  • Gloves

Personal Protection in Case of a Large Spill:

  • Splash goggles
  • Full suit
  • Dust respirator
  • Boots
  • Gloves
  • A self contained breathing apparatus should be used to avoid inhalation of the product.

Note: Suggested protective clothing might not be sufficient; consult a specialist BEFORE handling this product.

Regulation

United States [6]

Exposure Limit

Limit Values

HE Codes

Health Factors and TargetOrgans

OSHA PermissibleExposure Limit (PEL) – General Industry See 29CFR 1910.1000 Table Z-1

10 ppm

(50 mg/m3) TWA

HE3

Cataracts, jaundice, bloody urine,kidney and liver damage

HE7

Headache, tiredness, confusion Targetorgans: Brain, central nervous system

HE12

Haemolytic anaemia

HE14

Marked eye and skin irritation

OSHA PEL -Construction Industry See 29 CFR 1926.55 Appendix A

10 ppm

(50 mg/m3) TWA

HE3

Cataracts, jaundice, bloody urine,kidney and liver damage

HE7

Headache, tiredness, confusion Targetorgans: Brain, central nervous system

HE12

Haemolytic anaemia

HE14

Marked eye and skin irritation

OSHA PEL – Shipyard EmploymentSee 29CFR 1915.1000 Table Z-Shipyards

10 ppm

(50 mg/m3) TWA

HE3

Cataracts, jaundice, bloody urine, kidneyand liver damage

HE7

Headache, tiredness, confusion Targetorgans: Brain, central nervous system

HE12

Haemolytic anaemia

HE14

Marked eye and skin irritation Targetorgans: Eyes, skin

National Institute forOccupational Safety and Health (NIOSH) Recommended Exposure Limit (REL)

10 ppm

(50 mg/m3) TWA

 

15 ppm

(75 mg/m3) STEL

HE3

Jaundice, blood in urine, renalshutdown, optical neuritis, corneal damage

HE7

Headache, confusion, excitement Targetorgans: Brain, central nervous system

HE14

Eye irritation

American Conference ofGovernmental Industrial Hygienists (ACGIH) Threshold Limit Value (TLV) (2001)*

10 ppm

(52 mg/m3) TWA

 

15 ppm

(79 mg/m3) STEL

 

Skin; A4

HE3

Ocular toxicity (cataracts, opticalneuritis, lens opacities, retinal degeneration), jaundice, renal failure

HE7

Headache Target organs: Brain, centralnervous system

HE12

Haemolytic anaemia

HE14

Marked eye and respiratory tractirritation

CAL/OSHA PELs

10 ppm

(50 mg/m3) TWA

 

15 ppm (75 mg/m3)

STEL

HE3

Ocular toxicity (cataracts, opticalneuritis, lens opacities, retinal degeneration), jaundice, renal failure

HE7

Headache Target organs: Brain, centralnervous system

HE12

Haemolytic anaemia

HE14

Marked eye and respiratory tractirritation

Australia [7]

Safe Work Australia: For naphthalene, the eight-hour time weighted average (TWA) exposure limit is 10 ppm or 52mg/m3. The short term exposure limit (STEL) concentration should not to exceed 15ppm or 79mg/m3.

References

http://en.wikipedia.org/wiki/Naphthalene

http://www.hpa.org.uk/webc/HPAwebFile/HPAweb_C/1203084377836

http://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=239&tid=43

http://www.epa.gov/ttn/atw/hlthef/naphthal.html

http://www.sciencelab.com/msds.php?msdsId=9927671

https://www.osha.gov/dts/chemicalsampling/data/CH_255800.html

http://www.safeworkaustralia.gov.au/sites/SWA/about/Publications/Documents/772/Workplace-exposure-standards-airborne-contaminants.pdf

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