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General Description

Synonyms: beta-Methylnaphthalene

OSHA IMIS Code Number: M156

Chemical Abstracts Service (CAS) Registry Number: 91-57-6

NIOSH Registry of Toxic Effects of Chemical Substances (RTECS) Identification Number: QJ9635000

Chemical Description and Physical Properties:

crystals
molecular weight: 142.21
vapor pressure: 0.068 mmHg @ 20°C
molecular formula: C11H10
boiling point: 241°C
melting point: 35°C

Health Factors

Potential Symptoms: Eye irritation; cough. In mice, lung damage occurs by all routes of exposure (inhalation, oral, percutaneous, parenteral)

Health Effects: Irritation-Eyes---Mild (HE-16); Potential lung damage (HE-10)

Affected Organs: Eyes, respiratory system

Notes:

  1. OSHA does not have a PEL for 2-methylnaphthalene, to which workers at coke plants and refineries, as well as machine operators and aircraft engine mechanics, may be exposed. It is found in some solvents and in tobacco smoke.
  2. No cases of occupational toxicity from 2-methylnaphthalene have been reported, but caution is advised due to insufficient information about human health effects.
  3. Lung damage in mice is caused by the formation of reactive metabolites (by the P450 enzyme CYP2F2 in lung Clara cells) that bind covalently to lung proteins.
  4. In guinea pigs, major urinary metabolites of 2-methylnaphthalene are naphthoic acid and its conjugates with glucuronic acid and glycine, within 24 hours following oral administration of a 500-mg/kg dose. Similarly, in rats injected twice with a lower dose of radiolabeled 2-methylnaphthalene (0.3 mg/kg), approximately one-third of the radioactivity in urine was identified as 2-naphthoylglycine.
  5. Inhalational exposure of rats for 4 hours produced antinociception to a thermal stimulus in a concentration-dependent manner.
  6. The inhalational RD50 for decreasing the respiratory rate in mice by 50% (a measure of respiratory irritation) was reported to be 67 mg/m3 (12 ppm).

Literature Basis:

  • International Chemical Safety Cards (WHO/IPCS/ILO): 2-Methylnaphthalene.
  • Agency for Toxic Substances and Disease Registry (ATSDR): Toxicological profile for naphthalene, 1-methynaphthalene and 2-methylnaphthalene. US Government Printing Office 1995-639-298, 200 pp., 1995.
  • Korsak, Z., Majcherek, W. and Rydzynski, K.: Toxic effects of acute inhalation exposure to 1-methylnaphthalene and 2-methylnaphthalene in experimental animals. Int. J. Occup. Med. Environ. Health 11(4): 335-342, 1998.
  • Melancon, M.J., Rickert, D.E. and Lech, J.J.: Metabolism of 2-methylnaphthalene in the rat in vivo. I. Identification of 2-naphthoylglycine. Drug Metab. Dispos. 10(2): 128-133, 1982.
  • Schultz, M.A., Morin, D., Chang, A.-M., Buckpitt, A.: Metabolic capabilities of CYP2F2 with various pulmonary toxicants and its relative abundance in mouse lung subcompartments. J. Pharmacol. Exp. Ther. 296(2): 510-519, 2001.
  • Teshima, R., Nagamatsu, K., Ikebuchi, H., Kido, Y. and Terao, T.: In vivo and in vitro metabolism of 2-methylnaphthalene in the guinea pig. Drug. Metab. Dispos. 11(2): 152-157, 1983.

Date Last Revised: 05/13/2005

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