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| Last Updated:: 01/04/2016

Polycyclic Aromatic Hydrocarbons (PAH)

Polycyclic aromatic hydrocarbons (PAH) is an entire class of toxic chemicals, linked together by their unique chemical structure and reactive properties.


Many PAHs are known human carcinogens and genetic mutagens. In addition, there are particular prenatal health risks: prenatal exposure to PAHs is linked to childhood asthma, low birth weight, adverse birth outcomes including heart malformations, and DNA damage.


Infants found to have elevated PAH levels in their umbilical cord blood were 46% more likely to eventually score highly on the anxiety/depression scale than those with low PAH levels in cord blood.


Short for polycyclic aromatic hydrocarbons, PAHs describe chemicals that are often found together in groups of two or more.  PAHs are found naturally in the environment but they can also be man-made.  In their purest form, PAHs are solid and range in appearance from colorless to white or pale yellow-green.  PAHs are created when products like coal, oil, gas, and garbage are burned but the burning process is not complete. Although PAHs can exist in over 100 different combinations, the National Waste Minimization Program defines this group  using the Toxic Release Inventory reporting category for polycyclic aromatic compounds.


Chemicals included in this category, by name and CAS number, are: 


1. Benzo(a)anthracene, 56-55-3

2. Benzo(a)phenanthrene (chrysene), 218-01-9

3. Benzo(a)pyrene, 50-32-8  

4. Benzo(b)fluoranthene, 205-99-2 

5. Benzo(j)fluoranthene, 205-82-3 

6. Benzo(k)fluoranthene, 207-08-9 

7. Benzo(j,k)fluorene (fluoranthene), 206-44-0 

8. Benzo(r,s,t)pentaphene, 189-55-9 

9. Dibenz(a,h)acridine, 226-36-8 

10. Dibenz(a,j)acridine, 224-42-0 

11. Dibenzo(a,h)anthracene, 53-70-3 

12. Dibenzo(a,e)fluoranthene, 5385-75-1 

13. Dibenzo(a,e)pyrene, 192-65-4 

14. Dibenzo(a,h)pyrene, 189-64-0 

15. Dibenzo(a,l)pyrene, 191-30-0 

16. 7H-Dibenzo(c,g)carbazole, 194-59-2 

17. 7,12-Dimethylbenz(a)anthracene, 57-97-6 

18. Indeno(1,2,3-cd)pyrene 193-39-5 

19. 3-Methylcholanthrene, 56-49-5 

20. 5-Methylchrysene, 3697-24-3 

21. 1-Nitropyrene, 5522-43-0


Source: EPA