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Naphthalene

General Description

  • Synonyms: Naphthalin; Naphthaline; Naphthene
  • OSHA IMIS Code Number: 1810
  • Chemical Abstracts Service (CAS) Registry Number: 91-20-3
  • NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: QJ0525000
  • Department of Transportation Regulation Number (49 CFR 172.101) and Emergency Response Guidebook: 1334 133 (crude or refined); 2304 133 (molten)
  • NIOSH Pocket Guide to Chemical Hazards, Naphthalene: Physical description, chemical properties, potentially hazardous incompatibilities, and more
  • U.S. Environmental Protection Agency (EPA) Hazard Summary, Naphthalene: Uses, sources and potential exposure, acute and chronic health hazard information, and more

Exposure Limits and Health Effects

Exposure Limit Limit Values HE Codes Health Factors and Target Organs
OSHA Permissible Exposure Limit (PEL) - General Industry See 29 CFR 1910.1000 Table Z-1
  • 10 ppm
  • (50 mg/m3) TWA
HE3 Cataracts, jaundice, bloody urine, kidney and liver damage
HE7 Headache, tiredness, confusion Target organs: Brain, central nervous system
HE12 Hemolytic anemia
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 Target organs: Brain, central nervous system
HE12 Hemolytic anemia
HE14 Marked eye and skin irritation
OSHA PEL - Shipyard Employment See 29 CFR 1915.1000 Table Z-Shipyards
  • 10 ppm
  • (50 mg/m3) TWA
HE3 Cataracts, jaundice, bloody urine, kidney and liver damage
HE7 Headache, tiredness, confusion Target organs: Brain, central nervous system
HE12 Hemolytic anemia
HE14 Marked eye and skin irritation Target organs: Eyes, skin
National Institute for Occupational 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, renal shutdown, optical neuritis, corneal damage
HE7 Headache, confusion, excitement Target organs: Brain, central nervous system
HE14 Eye irritation
American Conference of Governmental 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, optical neuritis, lens opacities, retinal degeneration), jaundice, renal failure
HE7 Headache Target organs: Brain, central nervous system
HE12 Hemolytic anemia
HE14 Marked eye and respiratory tract irritation
CAL/OSHA PELs
  • 10 ppm
  • (50 mg/m3) TWA
  •  
  • 15 ppm (75 mg/m3)
  • STEL
HE3 Ocular toxicity (cataracts, optical neuritis, lens opacities, retinal degeneration), jaundice, renal failure
HE7 Headache Target organs: Brain, central nervous system
HE12 Hemolytic anemia
HE14 Marked eye and respiratory tract irritation

*In the ACGIH 2012 Notice of Intended Changes, ACGIH proposed the following limit values and notations: 5 ppm TWA; No STEL; Skin; A3; basis: upper respiratory tract irritation

National Toxicology Program (NTP) carcinogenic classification: Reasonably anticipated to be a human carcinogen (PDF)

International Agency for Research on Cancer (IARC) carcinogenic classification: Group 2B (PDF) (possibly carcinogenic to humans)

EPA carcinogenic classification: Carcinogenic potential cannot be determined

EPA Inhalation Reference Concentration (RfC): 3x10-3 mg/m3

Agency for Toxic Substances and Disease Registry (ATSDR) Inhalation Minimal Risk Level (MRL): 0.0007 ppm (chronic)

NIOSH Immediately Dangerous to Life or Health (IDLH) concentration: 250 ppm

Notes on Other Potential Health Effects and Hazards

  1. EPA's oral reference dose (daily oral exposure likely to be without an appreciable risk of deleterious effects during a lifetime) for naphthalene is 0.02 mg/kg/day (EPA 2000).
  2. At least one study has shown that exposure to naphthalene in the air at a workplace can lead to DNA strand breaks, which are often seen as a precursor to tumor formation (Marczynski et al. 2005).
  3. There have been numerous reports of hemolytic anemia and cataracts following occupational exposure to naphthalene (ATSDR 1995).
  4. Naphthalene in expired air has been studied as a biomarker of dermal and inhalational exposure to jet fuel, but the elimination in breath is fairly rapid, with a halftime of 19 to 25 minutes (Egeghy et al. 2003).
  5. Occupational monitoring of naphthalene exposure usually involves the measurement of the urinary metabolites 1-naphthol and 2-naphthol (Preuss et al. 2003).
  6. The EPA reference concentration is based on an inhalation study in mice in which hyperplasia and metaplasia in respiratory and olfactory epithelium, were observed  in nearly all the animals at 30 ppm, which was the lowest dose tested (EPA 1998).
  7. The NTP classification of naphthalene as reasonably anticipated to be carcinogenic to humans, and the IARC classification as Group 2B, possibly carcinogenic to humans, was based on an inhalation bioassay in rats and mice (IARC 2002).

Date Last Revised: 12/11/2012

Literature Basis

  • ACGIH: Documentation of the Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Naphthalene. 2001.
  • ATSDR: Toxicological Profile for Naphthalene, 1-Methylnaphthalene and 2-Methylnaphthalene. 2005.
  • Egeghy, P.P., Hauf-Cabalo, L., Gibson, R. and Rappaport, S.M.: Benzene and naphthalene in air and breath as indicators of exposure to jet fuel. Occup. Environ. Med. 60(12): 969-976, 2003.
  • EPA IRIS Napthalene (1998)
  • IARC Monographs on Evaluation of Carcinogenic Risks to Humans, Volume 82, Naphthalene, 2002
  • Marczynski, B. et al.: Genotoxic risk assessment in white blood cells of occupationally exposed workers before and after alteration of the polycyclic aromatic hydrocarbon (PAH) profile in the production material: comparison with PAH air and urinary metabolite levels. Int Arch Occup Environ Health 78(2): 97-108, 2005.
  • NIOSH: Occupational Health Guideline for Naphthalene. September 1978.
  • NIOSH/IPCS: International Chemical Safety Cards - Naphthalene. April 21, 2005.
  • National Toxicology Program (NTP). Toxicology and carcinogenesis studies of naphthalene in B6C3F1 mice (inhalation studies). Technical Report Series No. 410. NIH Publication No. 92-3141. (1992).
  • NTP Report on Carcinogens Napthalene (PDF).
  • Preuss, R., Angerer, J. and Drexler, H.: Naphthalene - an environmental and occupational toxicant. Int. Arch. Occup. Environ. Health 76(8): 556-576, 2003.

Monitoring Methods used by OSHA

Laboratory Sampling/Analytical Method:
  • Chromosorb 106 Tube (100/50 mg sections, 60/80 mesh)
  • analytical solvent: Carbon Disulfide
  • maximum volume: 10 Liters
  • maximum flow rate: 0.2 L/min (TWA)
  • maximum volume: 3 Liters
  • maximum flow rate: 0.2 L/min (STEL)
  • current analytical method: Gas Chromatography; GC/FID
  • method reference: OSHA Analytical Method (OSHA 35)
  • method classification: Fully Validated
  • note: Submit as a separate sample.

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