Polycyclic Aromatic Hydrocarbons

About Polycyclic Aromatic Hydrocarbons (PAHs)

PAHs are a group of compounds that occur naturally in coal and tar, or form during the incomplete combustion of organic material such as coal, oil, gas, wood, garbage and charbroiled meat [1]. PAHs usually occur as complex mixtures.

IARC has classified different individual PAHs as known, probable, and possible carcinogens, while others could not be classified [2]. Occupational exposure to PAHs during certain work processes causes lung cancer and non-melanoma skin cancer. There is some evidence it may also cause bladder cancer. Other health effects associated with PAH exposure include decreased immune function, kidney and liver damage, and asthma-like symptoms.

CAREX Canada estimates that approximately 350,000 Canadians are exposed to PAHs at work [3].

Burden of Cancer Results

Approximately 130 lung cancers, 50 skin cancers and 80 bladder cancers are suspected to be due to occupational PAH exposure each year, based on 2011 cancer statistics. This amounts to 0.6% of all lung cancers, 0.1% of all skin cancers, and 1% of all bladder cancers diagnosed annually in Canada. The cost of these newly diagnosed lung, non-melanoma skin and bladder cancer cases is $183 million annually.

Most PAH-related lung cancers occur among workers in the manufacturing and construction industries (see pie chart).

Exposure Reduction

Engineering controls to reduce exposure to PAHs include local exhaust ventilation systems, implementing systems to capture and remove PAHs from the air (e.g. fume scrubbing systems), and ensuring workers are enclosed and separated from contaminated air (e.g. by adding enclosed cabs on vehicles, or providing enclosed, pressurized rooms supplied with filtered air) [4,5]. Ensuring these controls are in place in key sectors where exposure levels are high can help reduce the health impact of PAHs.


References

  1. National Toxicology Program (NTP). Report on Carcinogens, 14th edition. Research Triangle Park, NC: U.S. Department of Health and Human Services, Public Health Service, 2016.
  2. International Agency for Research on Cancer. IARC Monographs Volume 92. Some Non-heterocyclic Polycyclic Aromatic Hydrocarbons and Some Related Exposures (2010).
  3. CAREX Canada. Polycyclic Aromatic Hydrocarbons Occupational Exposures Profile.
  4. dell’Omo M, Muzi G, Marchionna G, Latini L, Carrieri P, Paolemili P, et al. Preventive measures reduce exposure to polycyclic aromatic hydrocarbons at a graphite electrode plant. Occup Environ Med. 1998;55(6):401-6. 128.
  5. Australian Institute of Occupational Hygienists (AIOH) Exposure Standards Committee. Polycyclic aromatic hydrocarbons (PAHs) and occupational health issues. Tullamarine, Australia: 2016