Current External and Internal Exposure to Naphthalene of Workers Occupationally Exposed to Polycyclic Aromatic Hydrocarbons in Different Industries

Int Arch Occup Environ Health. 2005 Jun;78(5):355-62. doi: 10.1007/s00420-004-0593-3. Epub 2005 Apr 30.


Objectives: External and internal exposure to naphthalene was examined in the most important industries that are typically concerned with polycyclic aromatic hydrocarbon (PAH)-induced diseases (cancer). Furthermore, a control collective from the general population was investigated.

Methods: External naphthalene was determined by personal air sampling (n = 205). The internal exposure was examined by urinary metabolites 1-naphthol and 2-naphthol (n = 277).

Results: Highest median concentrations of naphthalene in air were found in converter infeed (93.2 microg/m3) and coal-tar distillation (35.8 microg/m3). Moderate and low levels were determined in coking plants (14.5 microg/m3) and in the production of refractories (6.1 microg/m3) and graphite electrodes (0.7 microg/m3). Biological monitoring revealed concentrations of the sum of both metabolites [(1+2)-NOL] in smokers to be increased by 1.6-6.4 times compared with that in non-smokers at the same workplaces. Among non-smokers we found high median (1+2)-NOL levels in converter bricklayers (120.1 microg/l), in coal-tar distillation workers (56.0 microg/l) and in coking plant workers (29.5 microg/l). (1+2)-NOL concentrations around 10 microg/l were found in the production of refractories and graphite electrodes. There was a rough coherency between external and internal naphthalene exposure. In the controls, median (1+2)-NOL concentrations were 10.9 microg/l in non-smokers' urine and 40.3 microg/l in smokers' urine samples.

Conclusions: Actual conditions of occupational hygiene at the workplaces investigated in this comprehensive study are better than those that current limit values of 50,000 microg/m3 (TLV, TRK) seem to induce. It has become obvious that tobacco smoking is a crucial confounding factor in biological monitoring of naphthalene-exposed humans, making interpretation of occupationally increased naphthol excretions very difficult at low exposure levels.

MeSH terms

  • Adult
  • Air Pollutants, Occupational
  • Carcinogens
  • Environmental Monitoring
  • Germany
  • Humans
  • Industry
  • Male
  • Middle Aged
  • Naphthalenes / analysis
  • Naphthalenes / urine*
  • Occupational Exposure / analysis*
  • Polycyclic Aromatic Hydrocarbons*


  • Air Pollutants, Occupational
  • Carcinogens
  • Naphthalenes
  • Polycyclic Aromatic Hydrocarbons
  • naphthalene