Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) consist of two or more fused aromatic rings containing only hydrogen and carbon atoms. 1-Hydroxypyrene (1-HP) is used for biological monitoring. "This BEI [Biological Exposure Index] is designed to assist industrial hygienists and other occupational health professionals in controlling occupational exposure to polycyclic aromatic hydrocarbons (PAHs) from all routes. . . . ACGIH recommends a benchmark value of 1 ug 1-HP/L in urine be considered a post-shift level indicating occupational exposure to PAHs." [ACGIH] Some references use the definition of "three or more" fused aromatic rings. [Sullivan, p. 1241] This definition excludes naphthalene and methylnaphthalenes. 

Table of Polycyclic Aromatic Hydrocarbons

HSDB

ACGIH

IARC

NTP

1,2-Dihydroaceanthrylene

641-48-5

 

 

3

 

1,4-Dimethylphenanthrene

22349-59-3

 

 

3

 

10-METHYLBENZ(A)ANTHRACENE 

2381-15-9

X

 

 

 

11-H-Benz(bc)aceanthrylene

202-94-8

 

 

3

 

12-METHYLBENZ(A)ANTHRACENE 

2422-79-9

X

 

 

 

13-H-Dibenzo(a,g)fluorene

207-83-0

 

 

3

 

1-Methylchrysene

3351-28-8

 

 

3

 

1-METHYLNAPHTHALENE

90-12-0

X

TLV, A4

 

 

1-METHYLPYRENE

2381-21-7

X

 

 

 

2,7-DIMETHYLPYRENE

15679-24-0

X

 

 

 

2-Methylchrysene

3351-32-4

 

 

3

 

2-Methylfluoranthene

33543-31-6

 

 

3

 

2-METHYLNAPHTHALENE

91-57-6

X

TLV, A4

 

 

2-Methylphenanthrene

832-69-9

 

 

3

 

2-METHYLPYRENE

3442-78-2

X

 

 

 

3-METHYLCHOLANTHRENE

56-49-5

X

 

 

 

3-Methylchrysene

3351-31-3

 

 

3

 

3-Methylfluoranthene

1706-01-0

 

 

3

 

4-H-Cyclopenta(def)chrysene

202-98-2

 

 

3

 

4-Methylchrysene

3351-30-2

 

 

3

 

5,6-Cyclopenteno-1,2-benzathracene

7099-43-6

 

 

3

 

5-Methylchrysene

3697-24-3

 

 

2B

R

6-Methylchrysene

1705-85-7

 

 

3

 

7,12-DIMETHYLBENZ(A)ANTHRACENE 

57-97-6

X

 

 

 

7-METHYLBENZ(A)ANTHRACENE 

2541-69-7

X

 

 

 

8-METHYLBENZ(A)ANTHRACENE 

2381-31-9

X

 

 

 

9,10-DIMETHYLANTHRACENE 

781-43-1

X

 

 

 

9-METHYLBENZ(A)ANTHRACENE 

2381-16-0

X

 

 

 

ACENAPHTHENE

83-32-9

X

 

3

 

ACENAPHTHYLENE

208-96-8

X

 

 

 

Acepyrene

25732-74-5

 

 

3

 

Anthanthrene

191-26-4

 

 

3

 

ANTHRACENE

120-12-7

X

 

 

 

ASPHALT

8052-42-4

X

TLV, A4, BEI

3

 

Benz(a)acridine

225-11-6

 

 

3

 

BENZ(A)ANTHRACENE

56-55-3

X

A2, BEI

2B

R

BENZ(C)ACRIDINE

225-51-4

X

 

3

 

Benz(i)aceanthrylene

211-91-6

 

 

3

 

Benz(j)aceanthrylene

203-33-5

 

 

2B

 

Benzo(a)fluoranthene

203-33-8

 

 

3

 

Benzo(a)fluorene

238-84-6

 

 

3

 

BENZO(A)PYRENE

50-32-8

X

A2, BEI

2A

R

Benzo(b)chrysene

214-17-5

 

 

3

 

BENZO(B)FLUORANTHENE

205-99-2

X

A2, BEI

2B

R

Benzo(b)fluorene

243-17-4

 

 

3

 

BENZO(C)CHRYSENE

194-69-4

X

 

 

 

Benzo(c)fluorene

205-12-9

 

 

3

 

Benzo(c)phenanthrene

195-19-7

 

 

2B

 

BENZO(E)PYRENE

192-97-2

X

 

3

 

BENZO(G)CHRYSENE

196-78-1

X

 

3

 

Benzo(ghi)fluoranthene

203-12-3

 

 

3

 

BENZO(GHI)PERYLENE

191-24-2

X

 

3

 

BENZO(J)FLUORANTHENE

205-82-3

X

 

2B

R

BENZO(K)FLUORANTHENE

207-08-9

X

 

2B

R

Carbon black

1333-86-4

X

TLV, A4

2B

 

Cholanthrene

479-23-2

X  

 

 

 

CHRYSENE

218-01-9

X

A3, BEI

2B

 

Coal gasification

 

 

 

1

 

COAL TAR

8007-45-2

X

 

 

 

COAL TAR CREOSOTE

8001-58-9

X

 

2A

 

Coal tar pitch volatiles

65996-93-2

 

TLV, A1, BEI

1

K

COAL TAR USP

NO CAS RN

X

 

 

 

Coal-tar distillation

 

 

 

1

 

Coal-tar pitch, paving & roofing with

 

 

 

1

 

Coke oven emissions

 

 

 

1

K

Coke production

 

 

 

1

 

Coronene

191-07-1

 

 

3

 

CREOSOTE, WOOD

8021-39-4

X

 

 

 

Cyclopenta(c,d)pyrene

27208-37-3

 

 

2A

 

Dibenz(a,c)anthracene

215-58-7

 

 

3

 

DIBENZ(A,H)ACRIDINE

226-36-8

X

 

2B

R

DIBENZ(A,H)ANTHRACENE

53-70-3

X

 

2A

R

DIBENZ(A,J)ACRIDINE

224-42-0

X

 

2B

R

Dibenz(a,j)anthracene

224-41-9

 

 

3

 

DIBENZ(C,H)ACRIDINE

224-53-3

X

 

 

 

DIBENZO(a,e)FLUORANTHENE 

5385-75-1

X

 

3

 

DIBENZO(A,E)PYRENE

192-65-4

X

 

3

R

DIBENZO(A,H)PYRENE

189-64-0

X

 

2B

R

DIBENZO(A,I)PYRENE

189-55-9

X

 

2B

R

DIBENZO(A,L)PYRENE

191-30-0

X

 

2A

R

DIBENZO(B,K)CHRYSENE

217-54-9

X

 

 

 

Dibenzo(e,l)pyrene

192-51-8

 

 

3

 

Dibenzo(h,rst)pentaphene

192-47-2

 

 

3

 

Diesel engine emissions

 

 

 

2A

R

FLUORANTHENE

206-44-0

X

 

3

 

FLUORENE

86-73-7

X

 

3

 

INDENO(1,2,3-CD)PYRENE

193-39-5

X

 

2B

R

Naphthalene

91-20-3

X

TLV, A4

2B

R

PERYLENE

198-55-0

X

 

 

 

PHENANTHRENE

85-01-8

X

 

3

 

Polycyclic aromatic hydrocarbons

130498-29-2

X

BEI

 

 

PYRENE

129-00-0

X

 

3

 

Shale oils

68308-34-9

1

Soots (Chimney sweeps)

 

 

 

1

 

Bolded = in the Haz-Map database; See in Glossary definitions of ACGIH, IARC, and NTP carcinogens.

"Data are not sufficient to justify a numerical BEI scientifically, based on health outcome or upon an airborne exposure (TLV). Therefore, the "Nq" notation is recommended due to insufficient data to support a numerical BEI." [ACGIH]

"PAHs are not currently produced for commercial use in the United States. . . . PAHs do not usually enter the body through the skin under normal conditions; however, small amount could enter the body if there is contact with products or oils containing high concentrations of PAHs." [NTP]

PAHs are solids at room temperature. Approximately 100 compounds have been identified. "Metabolism of PAHs occurs primarily (but not solely) in the liver by the P450 mixed-function oxidase system. . . . Binding of PAH metabolites to DNA is believed to be the mechanism of PAH-induced carcinogenesis. . . . Skin-painting studies in a variety of animal models have demonstrated the ability of benz[a]anthracene and indeno[1,2,3-c,d]pyrene to induce skin tumors, and these therefore are considered to be complete carcinogens (both initiators and promoters). Anthracene, fuoranthene, fluorene, phenanthrene, and pyrene do not act as complete carcinogens." [Sullivan, p. 1242-3

In addition to being carcinogenic and mutagenic, the PAHs have been found to be potent immunosuppressants." [Klaassen, p. 526]

Pyrene is not a carcinogen, but coal tar pitch volatiles, a mixture of PAHs, are confirmed human carcinogens. [ACGIH]

"The carcinogenic potential of individual chemicals varies by many orders of magnitude. PAHs almost always occur in mixtures; therefore the carcinogenicity to humans cannot be linked to individual chemicals. . . . This biomarker [1-HP] serves as an efficient complement to air-borne sampling, because of the significant dermal absorption of these compounds." [Rosenstock, p. 1059]

"The combustion process that release PAH invariably produce a variety of compounds, and in fact, it is difficult or impossible to ascribe health effects in humans to particular members of the PAH family. Hence, PAH are usually treated as a group for the purpose of risk assessment." [Rom, p. 1240]

"Several of the complex mixtures (coal tars and pitch, mineral oils, shale oils, soots) that are classified as IARC group 1 carcinogens include PAHs and several of the industries in which cancer risks have been identified (e.g., coal gasification, coke production, aluminum production, iron and steel founding) are industries in which PAHs are prevalent. Paradoxically, however, there are no specific PAHs on the group 1 list. The highest classed PAHs are in group 2A. . . . Because of the non-feasibility of measuring all PAHs when they are measured for industrial hygiene purposes, there has typically been a single marker of PAHs, often benzo(a)pyrene." [Schottenfeld, p. 334]

Polycyclic organic matter, or POM, as defined by the U.S. EPA in the Federal Clean Air Act comprises a large and varied class of chemicals compounds, including polycyclic aromatic hydrocarbons (PAH), and nitro-PAHs, which are known carcinogens and mutagens. . . . Although the combustion of fossil fuels is a ubiquitous source of POM in the urban ambient environment, it is not the only source of human exposure to POM, and for some individuals it may not be the predominant source. Other human exposure to POM comes from inhaling wood and tobacco smoke, and from diet (e.g., from the consumption of grilled meat). [Schottenfeld, p. 358]

Heterocyclic aromatic compounds (HACs) are "PAHs having any one carbon atom in a ring replaced by a nitrogen, oxygen, or sulfur atom." [HSDB]

HACs CAS # HSDB IARC

7H-Dibenzo(c,g)carbazole   

194-59-2

X 2B

Dibenzothiophene   

132-65-0

X  

Dibenzofuran   

132-64-9

X  
11-Thiabenzo(a)fluorene 239-35-0    

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Revised: April 28, 2015

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