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1999-12-00 Toxic Air Contaminant (TAC) Identification List

This page last reviewed July 15, 2008

Toxic Air Contaminant (TAC) Identification List

December 1999

Substance By Category

Click on the ++ to view its chemical summary from the Office of Environmental Health Hazard and Assessment website.

Category I

Category IIa

Category IIb

Category IIIa / b

Category IVa

Category IVb

Category V

Category VI


Category I

Substances identified as Toxic Air Contaminants, known to be emitted in California, with a full set of
health values reviewed by the Scientific Review Panel.

Click on a substance name to view its fact sheet from the 1997 Toxic Air Contaminant Identification List Summaries.
Please note some of the health values have changed since 1997.

Click on the ++ to view its chemical summary from the Office of Environmental Health Hazard
and Assessment website.

Substance

CAS
Number

Cancer
Potency
Value

Chronic
Reference
Exposure Level

Acute Reference
Exposure Level

*

Perchloroethylene (Tetrachloroethylene)

127-18-4

++

++

++

  (There is a potential for 12 substances to move into this category after the SRP has reviewed the noncancer chronic Reference Exposure Levels being developed under the Air Toxics "Hot Spots" Program.)        

Category IIa

Substances identified as Toxic Air Contaminants, known to be emitted in California, with one or more
health values under development by the Office of Environmental Health Hazard Assessment for
review by the Scientific Review Panel.

Click on a substance name to view its fact sheet from the 1997 Toxic Air Contaminant Identification List Summaries.
Please note some of the health values have changed since 1997.

Click on the ++ to view its chemical summary from the Office of Environmental Health Hazard
and Assessment website.

Substance

CAS
Number

Cancer
Potency
Value
(Note 1)

Chronic
Reference
Exposure Level
(Note 2)

Acute Reference
Exposure Level
(Note 3)

  Acetaldehyde

75-07-0

++

++

Limited Data Available

  Acetamide

60-35-5

++

Limited Data Available

Limited Data Available

+

Acrolein

107-02-8

i (Note 1)

X

++

  Acrylamide

79-06-1

++

X

Limited Data Available

  Acrylic Acid

79-10-7

ii (Note 1)

X

++

  Acrylonitrile

107-13-1

++

X

Limited Data Available

  Allyl Chloride

107-05-1

++

X

Limited Data Available

  Aniline

62-53-3

++

X

Limited Data Available

  Antimony and Compounds (Note 4)

7440-36-0

ii (Note 1)

Limited Data Available

Limited Data Available

       Antimony Trioxide

1309-64-4

i (Note 1)

X

Limited Data Available

*+

Inorganic Arsenic and Arsenic Compounds
(Inoganic Including Arsine) (Note 4)

7440-38-2

++

X

++

       Arsine

7784-42-1

ii (Note 1)

X

++

*

Asbestos [Asbestiform Varieties of Serpentine (Chrysotile), Riebeckite (Crocidolite), Cummingtonite-Grunerite (Amosite), Tremolite, Actinolite, and Anthophyllite]

1332-21-4

++

Limited Data Available

Limited Data Available

*

Benzene (Including Benzene from Gasoline)

71-43-2

++

X

++

  Benzyl Chloride

100-44-7

++

Limited Data Available

++

  Beryllium and Compounds (Note 4)

7440-41-7

++

X

Limited Data Available

  Bis(Chloromethyl)Ether

542-88-1

++

Limited Data Available

Limited Data Available

  Bis(2-Ethylhexyl)Phthalate (DEHP)

117-81-7

++

X

Limited Data Available

*

1,3-Butadiene

106-99-0

++

X

Limited Data Available

*

Cadmium and Compounds (Note 4)
(Metallic Cadmium and Cadmium Compounds)

7440-43-9

++

X

Limited Data Available

  Carbon Disulfide

75-15-0

ii (Note 1)

X

++

*

Carbon Tetrachloride (Tetrachloromethane)

56-23-5

++

X

++

*

Chlorinated Dibenzo-P-Dioxins (Note 5)

N/A

++

X

Limited Data Available

       2,3,7,8-Tetrachlorodibenzo-P-Dioxin

1746-01-6

++

X

Limited Data Available

    International Toxicity Equivalency Factors:        
       1,2,3,4,6,7,8-Heptachlorodibenzo-P-Dioxin

35822-46-9

++

X

Limited Data Available

       1,2,3,4,7,8-Hexachlorodibenzo-P-Dioxin

39227-28-6

++

X

Limited Data Available

       1,2,3,6,7,8-Hexachlorodibenzo-P-Dioxin

57653-85-7

++

X

Limited Data Available

       1,2,3,7,8,9-Hexachlorodibenzo-P-Dioxin

19408-74-3

++

X

Limited Data Available

       1,2,3,4,6,7,8,9-Octachlorodibenzo-P-Dioxin

3268-87-9

++

X

Limited Data Available

       1,2,3,7,8-Pentachlorodibenzo-P-Dioxin

40321-76-4

++

X

Limited Data Available

*

Chlorinated Dibenzofurans (Note 5)

N/A

++

X

Limited Data Available

 

  International Toxicity Equivalency Factors:        
       2,3,7,8-Tetrachlorodibenzofuran

5120-73-19

++

X

Limited Data Available

       1,2,3,4,7,8-Hexachlorodibenzofuran

70648-26-9

++

X

Limited Data Available

       1,2,3,6,7,8-Hexachlorodibenzofuran

57117-44-9

++

X

Limited Data Available

       1,2,3,7,8,9-Hexachlorodibenzofuran

72918-21-9

++

X

Limited Data Available

       2,3,4,6,7,8-Hexachlorodibenzofuran

60851-34-5

++

X

Limited Data Available

       1,2,3,4,6,7,8-Heptachlorodibenzofuran

67562-39-4

++

X

Limited Data Available

       1,2,3,4,7,8,9-Heptachlorodibenzofuran

55673-89-7

++

X

Limited Data Available

       1,2,3,4,6,7,8,9-Octachlorodibenzofuran

39001-02-0

++

X

Limited Data Available

       1,2,3,7,8-Pentachlorodibenzofuran

57117-41-6

++

X

Limited Data Available

       2,3,4,7,8-Pentachlorodibenzofuran

57117-31-4

++

X

Limited Data Available

+

Chlorine

7782-50-5

ii (Note 1)

X

++

  Chlorobenzene

108-90-7

ii (Note 1)

X

Limited Data Available

*

Chloroform

67-66-3

++

X

++

+

Chromium and Compounds (Note 4)

7440-47-3

ii (Note 1)

Limited Data Available

Limited Data Available

*

Chromium (VI)

18540-29-9

++

X

Limited Data Available

  Cobalt and Compounds (Note 4)

7440-48-4

i (Note 1)

X

Limited Data Available

  Cresols / Cresylic Acid (Isomers and Mixture)

1319-77-3

ii (Note 1)

X

Limited Data Available

+

Cyanide Compounds (Notes 4 and 11)

57-12-5

ii (Note 1)

Limited Data Available

++

+

1,4-Dichlorobenzene

106-46-7

++

X

Limited Data Available

  3,3-Dichlorobenzidene

91-94-1

++

Limited Data Available

Limited Data Available

  Diethanolamine

111-42-2

ii (Note 1 and 6)

X

Limited Data Available

  Dimethyl Formamide

68-12-2

ii (Note 1)

X

Limited Data Available

  1,4-Dioxane (1,4-Diethyleneoxide)

123-91-1

++

X

++

  Epichlorohydrin (1-Chloro-2,3-Epoxypropane)

106-89-8

++

X

++

  1,2-Epoxybutane

106-88-7

i (Note 1)

X

Limited Data Available

  Ethyl Benzene

100-41-4

ii (Note 1)

X

Limited Data Available

  Ethyl Carbamate (Urethane)

51-79-6

++

Limited Data Available

Limited Data Available

  Ethyl Chloride (Chloroethane)

75-00-3

ii (Note 1)

X

Limited Data Available

*

Ethylene Dibromide (1,2-Dibromoethane)

106-93-4

++

X

Limited Data Available

*

Ethylene Dichloride (1,2-Dichloroethane)

107-06-2

++

X

Limited Data Available

  Ethylene Glycol

107-21-1

ii (Note 1)

X

Limited Data Available

*+

Ethylene Oxide (1,2-Epoxyethane)

75-21-8

++

X

Limited Data Available

  Ethylene Thiourea

96-45-7

++

X

Limited Data Available

  Ethylidene Dichloride (1,1-Dichloroethane)

75-34-3

++

Limited Data Available

Limited Data Available

*+

Formaldehyde

50-00-0

++

X

++

  Glycol Ethers (Note 4 and 7)

N/A

ii (Note 1)

X

++

+

     Ethylene Glycol Monobutyl Ether

111-76-2

ii (Note 1)

X

++

       Ethylene Glycol Monoethyl Ether

110-80-5

ii (Note 1)

X

++

       Ethylene Glycol Monoethyl Ether Acetate

111-15-9

ii (Note 1)

X

++

       Ethylene Glycol Monomethyl Ether

109-86-4

ii (Note 1)

X

++

       Ethylene Glycol Monomethyl Ether Acetate

110-49-6

ii (Note 1)

X

Limited Data Available

  Hexachlorobenzene

118-74-1

++

X

Limited Data Available

  Hexachloroethane

67-72-1

i (Note 1)

X

Limited Data Available

  Hexamethylene-1,6-diisocyanate

822-06-0

ii (Note 1)

X

Limited Data Available

  Hexane

110-54-3

ii (Note 1)

X

Limited Data Available

  Hydrazine

302-01-2

++

X

Limited Data Available

+

Hydrochloric Acid

7647-01-0

ii (Note 1)

X

++

  Hydrogen Aluoride (Hydrofluoric Acid)

7664-39-3

ii (Note 1)

X

++

  Isophorone

78-59-1

i (Note 1)

X

Limited Data Available

*

Inorganic Lead and Inorganic Lead Compounds
(Includes Elemental Lead) (Note 4)

N/A

++

Limited Data Available
(Note 8)

Limited Data Available

  Lead Compounds (Does Not Include
Elemental Lead) (Note 4)

7439-92-1

i (Note 1)

Limited Data Available

Limited Data Available

+

Lindane

58-89-9

++

X

Limited Data Available

  Maleic Anhydride

108-31-6

ii (Note 1)

X

Limited Data Available

+

Manganese and Compounds (Note 4)

7439-96-5

ii (Note 1)

X

Limited Data Available

  Mercury and Compounds (Note 4)

7439-97-6

ii (Note 1)

X

++

       Mercuric Chloride

 7487-94-7

i (Note 1)

Limited Data Available

Limited Data Available

+

Methanol

67-56-1

ii (Note 1)

X

++

+

Methyl Bromide (Bromomethane)

74-83-9

ii (Note 1)

X

++

  Methyl Chloroform (1,1,1-Trichloroethane)

71-55-6

ii (Note 1)

X

++

  Methyl Ethyl Ketone (2-Butanone)

78-93-3

ii (Note 1)

X

++

  Methyl Isocyanate

624-83-9

ii (Note 1)

X

Limited Data Available

  Methyl Methacrylate

80-62-6

iii (Note 1)

X

Limited Data Available

0

Methyl Tertiary Butyl Ether

1634-04-4

++

(Note 15)

Limited Data Available

  4,4-Methylene Bis(2-Chloroaniline)

101-14-4

++

Limited Data Available

Limited Data Available

*

Methylene Chloride (Dichloromethane)

75-09-2

++

X

++

  4,4-Methylenedianiline

101-77-9

++

X

Limited Data Available

  Methylene Diphenyl Diisocyanate

101-68-8

ii (Note 1)

X

Limited Data Available

  Naphthalene

91-20-3

ii (Note 1)

X

Limited Data Available

*

Nickel and Compounds (Note 4)
(Metallic Nickel and Inorganic Nickel Compounds)

7440-02-0

++

X

++

  Nitrobenzene

98-95-3

i (Note 1)

X

Limited Data Available

  2-Nitropropane

79-46-9

i (Note 1)

X

Limited Data Available

  N-Nitrosodimethylamine

62-75-9

++

Limited Data Available

Limited Data Available

  N-Nitrosomorpholine

59-89-2

++

Limited Data Available

Limited Data Available

*

Particulate Emissions from Diesel-Fueled Engines

N/A

++

++

Limited Data Available

+

Pentachlorophenol

87-86-5

++

X

Limited Data Available

  Phenol

108-95-2

ii (Note 1)

X

++

  Phosgene

75-44-5

ii (Note 1)

X

++

  Phosphine

7803-51-2

ii (Note 1)

X

Limited Data Available

+

Phosphorus

7723-14-0

ii (Note 1)

X

Limited Data Available

  Phthalic Anhydride

85-44-9

ii (Note 1)

X

Limited Data Available

  Polychlorinated Biphenyls (Aroclors)

1336-36-3

++

Limited Data Available

Limited Data Available

  Polycyclic Organic Matter (Note 9)

 

     
  Polycyclic Aromatic Hydrocarbon (PAH)

 

     
     Including but not limited to:        
  Benzo[a]pyrene (Note 10)

50-32-8

++

Limited Data Available

Limited Data Available

  Potency Equivalency Factors for PAHs and
PAH-Derivatives (Note 10)		        
       Benz[a]anthracene

56-55-3

++

Limited Data Available

No Data
Available

       Benzo[b]fluoranthene

205-99-2

++

Limited Data Available

No Data
Available

       Benzo[j]fluoranthene

205-82-3

++

Limited Data Available

No Data
Available

       Benzo[k]fluoranthene

207-08-9

++

Limited Data Available

No Data
Available

       Chrysene

218-01-9

++

Limited Data Available

No Data
Available

       Dibenz[a,h]acridine

226-36-8

++

Limited Data Available

No Data
Available

       Dibenz[a,j]acridine

224-42-0

++

Limited Data Available

No Data
Available

       Dibenz[a,h]anthracene

53-70-3

++

Limited Data Available

No Data
Available

       Dibenzo[a,e]pyrene

192-65-4

++

Limited Data Available

No Data
Available

       Dibenzo[a,h]pyrene

189-64-0

++

Limited Data Available

No Data
Available

       Dibenzo[a,i]pyrene

189-55-9

++

Limited Data Available

No Data
Available

       Dibenzo[a,l]pyrene

191-30-0

++

Limited Data Available

No Data
Available

       7H-Dibenzo[c,g]carbazole

194-59-2

++

Limited Data Available

No Data
Available

       7,12-Dimethylbenz[a]anthracene

57-97-6

++

Limited Data Available

Limited Data Available

       1,6-Dinitropyrene

4239-76-48

++

Limited Data Available

No Data
Available

       1,8-Dinitropyrene

4239-76-59

++

Limited Data Available

No Data
Available

       Indeno[1,2,3-Cd]Pyrene

193-39-5

++

Limited Data Available

No Data
Available

       3-Methylcholanthrene

56-49-5

++

Limited Data Available

Limited Data Available

       5-Methylchrysene

3697-24-3

++

Limited Data Available

No Data
Available

       5-Nitroacenaphthene

602-87-9

++

Limited Data Available

No Data
Available

       6-Nitrochrysene

7496-02-8

++

Limited Data Available

No Data
Available

       2-Nitrofluorene

607-57-8

++

Limited Data Available

No Data
Available

       1-Nitropyrene

5522-43-0

++

Limited Data Available

Limited Data Available

       4-Nitropyrene

57835-92-4

++

Limited Data Available

No Data
Available

  1,3-Propane Sultone

1120-71-4

++

Limited Data Available

Limited Data Available

+

Propylene Oxide

75-56-9

++

X

++

  Selenium and Compounds (Note 4)

7782-49-2

ii (Note 1)

X

Limited Data Available

     Hydrogen Selenide

7783-07-5

ii (Note 1)

X

++

0

Styrene

100-42-5

i (Note 1)

X

++

  Styrene Oxide

96-09-3

i (Note 1)

X

Limited Data Available

  1,1,2,2-Tetrachloroethane

79-34-5

++

X

Limited Data Available

  Toluene

108-88-3

ii (Note 1)

X

++

  Toluene-2,4-Diisocyanate

584-84-9

++

X

Limited Data Available

  1,1,2-Trichloroethane

79-00-5

++

X

Limited Data Available

*

Trichloroethylene

79-01-6

++

X

Limited Data Available

  2,4,6-Trichlorophenol

88-06-2

++

Limited Data Available

Limited Data Available

  Triethylamine

121-44-8

ii (Note 1)

X

++

  Vinyl Ccetate

108-05-4

i (Note 1)

X

Limited Data Available

*

Vinyl Chloride (Chloroethylene)

75-01-4

++

X

++

  Vinylidene Chloride (1,1-Dichloroethylene)

75-35-4

ii (Note 1)

X

Limited Data Available

+

Xylenes (Mixed Isomers)

1330-20-7

ii (Note 1)

X

++

  M-Xylene

108-38-3

ii (Note 1)

X

++

  O-Xylene

95-47-6

ii (Note 1)

X

++

  P-Xylene

106-42-3

ii (Note 1)

X

++


Category IIb

Substances NOT identified as Toxic Air Contaminants, known to be emitted in California, with one or more
health values under development by the Office of Environmental Health Hazard Assessment for
review by the Scientific Review Panel.

Click on a substance name to view its fact sheet from the 1997 Toxic Air Contaminant Identification List Summaries.
Please note some of the health values have changed since 1997.

Click on the ++ to view its chemical summary from the Office of Environmental Health Hazard
and Assessment website.

Substance

CAS
Number

Cancer
Potency
Value
(Note 1)

Chronic
Reference
Exposure Level
(Note 2)

Acute Reference
Exposure Level
(Note 3)

  Ammonia

7664-41-7

ii (Note 1)

X

++

+

Chlorine Dioxide

10049-04-4

ii (Note 1)

X

Limited Data Available

+

Chloropicrin

76-06-2

ii (Note 1)

X

++

+

Copper and Compounds (Note 4)

7440-50-8

ii (Note 1)

Limited Data Available

++

+

Creosotes

N/A

i (Note 1)

Limited Data Available

Limited Data Available

+

Ethylene

74-85-1

ii (Note 1)

X

Limited Data Aavailable

+

Glutaraldehyde

111-30-8

ii (Note 1)

X

Limited Data Available

  Hexachlorocyclohexanes

608-73-1

++

X

Limited Aata Available

  Hydrogen Sulfide

7783-06-4

ii (Note 1)

X

++

+

Isopropyl Alcohol

67-63-0

ii (Note 1)

X

++

  Michler's Ketone (4,4'-Bis(Dimethylamino)Benzophenone)

90-94-8

++

Limited Data Available

Limited Data Available

  Nitric Ccid

7697-37-2

ii (Note 1)

X

++

+

Phosphoric Acid

7664-38-2

ii (Note 1)

X

Limited Data Available

+

Silver and Compounds (Note 4)

7440-22-4

ii (Note 1)

X

Limited Data Available

+

Sodium Cydroxide

1310-73-2

ii (Note 1)

X

++

+

Sulfuric Acid

7664-93-9

ii (Note 1)

X

++

+

Zinc and Compounds (Note 4)

7440-66-6

ii (Note 1)

X

Limited Data Available


Category III

Substances known to be emitted in California and are NOMINATED for development of
health values or additional health values.

Click on a substance name to view its fact sheet from the 1997 Toxic Air Contaminant Identification List Summaries.
Please note some of the health values have changed since 1997.

Category IIIa

 

Category IIIb

 

Identified as Toxic Air Contaminants

 

Not Identified as Toxic
Air Contaminants

 

Substance

CAS
Number

Substance

CAS
Number

  Methyl Tertiary Butyl Ether (Note 15) (Substance also in Category IIa)

1634-04-4

Crystalline Silica

7631-86-9

  Polycyclic Organic Matter (Note 9)
Other PAHs and Nitro-PAHs not listed in Category IIa or IVa. (Specific PAHs still to be determined.)

N/A

   
  Styrene (Substance also in Category IIa.)

100-42-5

   

Category IVa

Substance identified as Toxic Air Contaminants, known to be emitted in California and are
TO BE EVALUATED for entry into Category III.

Click on a substance name to view its fact sheet from the 1997 Toxic Air Contaminant Identification List Summaries.
Please note some of the health values have changed since 1997.

Substance

CAS
Number

Substance

CAS
Number

  Acetonitrile

75-05-8

  Hydroquinone

123-31-9

  Acetophenone

98-86-2

  Methyl Chloride (Chloromethane)

74-87-3

  O-Anisidine

90-04-0

  Methyl Hydrazine

60-34-4

  Biphenyl

92-52-4

  Methyl Isobutyl Ketone (Hexone)

108-10-1

  Carbonyl Sulfide

463-58-1

+

Pentachloronitrobenzene (Quintobenzene)

82-68-8

  Catechol

120-80-9

  P-Phenylenediamine

106-50-3

  Chloroacetic Acid

79-11-8

  Polycyclic Organic Matter (POM) (Note 9)

N/A

  Chlorobenzilate

510-15-6

  Other POMs not listed in Category IIa or III
including but not limited to:		  
  Chloroprene

126-99-8

  Cumene

98-82-8

       Anthracene

120-12-7

  Dibenzofuran

132-64-9

  Propionaldehyde

123-38-6

  Dibutylphthalate

84-74-2

  Propylene Dichloride

78-87-5

+

1,3-Dichloropropene (Telone)

542-75-6

  1,2-Propylenimine (2-Methyl Aziridine)

75-55-8

  1,1-Dimethyl Hydrazine

57-14-7

  Radionuclides (Including Radon) (Note 12)

N/A

  Dimethyl Phthalate

131-11-3

  Titanium Tetrachloride

7550-45-0

  Dimethyl Sulfate

77-78-1

  1,2,4-Trichlorobenzene

120-82-1

  Ethyl Acrylate

140-88-5

  2,2,4-Trimethylpentane

540-84-1

  Fine Mineral Fibers (Note 13)

N/A

     

Category IVba

Substance NOT identified as Toxic Air Contaminants, known to be emitted in California and are
TO BE EVALUATED for entry into Category III.

Click on a substance name to view its fact sheet from the 1997 Toxic Air Contaminant Identification List Summaries.
Please note some of the health values have changed since 1997.

Substance

CAS
Number

Substance

CAS
Number

+

Aluminum and Compounds (Note 4)

7429-90-5

  Cyclohexane

110-82-7

  Ammonium Nitrate

6484-52-2

  Decabromodiphenyl Oxide

1163-19-5

  Ammonium Sulfate

7783-20-2

  Dialkylnitrosamines

N/A

  Barium and Compounds (Note 4)

7440-39-3

  Diaminotoluene (Mixed Isomers)

N/A

  Benzoyl Chloride

98-88-4

  Dicofol

115-32-2

  Bis(2-Ethylhexyl)Adipate

103-23-1

  Environmental Tobacco Smoke (Note 14)

N/A

  Bromine and Compounds (Inorganic) (Note 4)

7726-95-6

  Gasoline Vapors

N/A

  Butyl Acrylate

141-32-2

  4,4'-Isopropylidenediphenol

80-05-7

+

N-Butyl Alcohol

71-36-3

  Molybdenum Trioxide

1313-27-5

  Sec-Butyl Alcohol

78-92-2

  Nitrilotriacetic Acid

139-13-9

  Tert-Butyl Alcohol

75-65-0

  Peracetic Acid

79-21-0

  Butyl Benzyl Bhthalate

85-68-7

+

2-Phenylphenol

90-43-7

  Carbon Black and Carbon Black Extracts

1333-86-4

  Propene

115-07-1

  Chlorinated Fluorocarbons

N/A

  Terephthalic Acid

100-21-0

  Chlorophenols

N/A

  Thiourea

62-56-6

  Cumene Hydroperoxide

80-15-9

  1,2,4-Trimethylbenzene

95-63-6


Category V

Substance identified as Toxic Air Contaminants, and NOT KNOWN TO BE EMITTED from stationary source
facilities in California based on information from the AB 2588 Air Toxic "Hot Spots" Program
and the California Toxic Release Inventory.

Click on a substance name to view its fact sheet from the 1997 Toxic Air Contaminant Identification List Summaries.
Please note some of the health values have changed since 1997.

Substance

CAS
Number

Substance

CAS
Number

  2-Acetylaminofluorene

53-96-3

  3,3-Dimethyl Benzidine

119-93-7

  4-Aminobiphenyl

92-67-1

  Dimethyl Carbamoyl Chloride

79-44-7

  Benzidine

92-87-5

  2,4-Dinitrophenol

51-28-5

  Benzotrichloride

98-07-7

  2,4-Dinitrotoluene

121-14-2

  Bromoform

75-25-2

  1,2-Diphenylhydrazine

122-66-7

  Calcium Cyanamide

156-62-7

  Ethylene Imine (Aziridine)

151-56-4

  Caprolactam

105-60-2

  Heptachlor

76-44-8

  Chloramben

133-90-4

  Hexachlorobutadiene

87-68-3

  Chlordane

57-74-9

  Hexachlorocyclopentadiene

77-47-4

  2-Chloroacetophenone

532-27-4

  Hexamethylphosphoramide

680-31-9

  Chloromethyl Methyl Ether

107-30-2

  Methyl Iodide (Iodomethane)

74-88-4

  Coke Oven Emissions

N/A

  4-Nitrobiphenyl

92-93-3

  O-Cresol

95-48-7

  4-Nitrophenol

100-02-7

  P-Cresol

106-44-5

  N-Nitroso-N-Methylurea

684-93-5

  DDE (P,P-Dichlorodiphenyldichloroethylene) 

72-55-9

  Parathion

56-38-2

  Diazomethane

334-88-3

  Beta-Propiolactone

57-57-8

  1,2-Dibromo-3-Chloropropane

96-12-8

  Quinoline

91-22-5

  Dichloroethyl Ether (Bis(2-Chloroethyl)Ether)

111-44-4

  Quinone

106-51-4

  2,4-Toluene Diamine

95-80-7

  N,N-Diethyl Aniline (N,N-Dimethyl Aniline)

121-69-7

  O-Toluidine

95-53-4

  Diethyl Sulfate

64-67-5

  Toxaphene (Chlorinated Camphene)

8001-35-2

  3,3-Dimethoxybenzidine

119-90-4

  2,4,5-Trichlorophenol

95-95-4

  4-Dimethyl Aminoazobenzene

60-11-7

  Vinyl Bromide

593-60-2


Category VI

Substances identified as Toxic Air Contaminants, NOT KNOWN TO BE EMITTED from stationary source
facilities in California, and are active ingredients in pesticides in California.

For futher information regarding the pesticidal uses of these compounds,
please contact the Department of Pesticide Regulation

Click on a substance name to view its fact sheet from the 1997 Toxic Air Contaminant Identification List Summaries.
Please note some of the health values have changed since 1997.

Substance

CAS
Number

Substance

CAS
Number

+

Captan

133-06-2

+

Dichlorvos

62-73-7

+

Carbaryl

63-25-2

+

Methoxychlor

72-43-5

+

M-Cresol

108-39-4

+

Propoxur (Baygon)

114-26-1

+

2,4-D, Salts and Esters (2,4-Dichlorophenoxyacetic Acid)

94-75-7

+

Trifluralin

1582-09-8


Footnotes

*

Substances which have already been identified by the Air Resources Board as Toxic Air Contaminants through a
comprehensive AB 1807 risk assessment and which have health values developed by the Office of Environmental
Health Hazard Assessment and approved by the Scientific Review Panel. A full risk assessment report is available.

**

AB 1807, Statutes 1983, chapter 1047, Health & Safety Code sections 39650 et. seq.

AB 2728, Statutes 1992, chapter 1161, Health & Safety Code sections 39655 et. seq.

a

To be listed as a Toxic Air Contaminant, these substances will go though a comprehensive AB 1807
risk assessment.

++

Health value reviewed by the Scientific Review Panel.

X

Health value under development by the Office of Environmental Health Hazard Assessment for review by the Scientific Review Panel.

0

These substances have been nominated for the development of additional health values.

+

These substances are active ingredients in pesticides in California. For further information regarding the
esticidal uses of these compounds, please contact the Department of Pesticide Regulation.

Note 1:

Substances in Category IIa and IIb without a draft or Scientific Review Panel reviewed Cancer Potency Value
have been divided into 3 groups depending on their cancer classification by the U.S. Environmental Protection Agency (U.S. EPA) or the International Agency for Research on Cancer (IARC).

i

Classified by U.S. EPA and / or IARC as a probable or possible human carcinogen
(Group B1, B2, C, 2A, or 2B substances);

ii

Classified by U.S. EPA and / or IARC as insufficient/inadequate data exist to classify
as to carcinogenicity to humans (Group 3 or D substances), or no data or value available
at this time;

iii

Considered not likely to be carcinogenic to humans by U.S. EPA and / or IARC
(Group 4 or E substances).

Note 2:

The literature was reviewed for substances in Category IIa & IIb without a draft or Scientific Review Panel reviewed Chronic Reference Exposure Level. "Limited data available" was added to the row if some chronic toxicity data was found in the literature. "No data available" was added to the row if no chronic toxicity data
was found in the literature.

Note 3:

The literature was reviewed for substances in Category IIa & IIb without a draft or Scientific Review Panel reviewed Acute Reference Exposure Level. "Limited data available" was added to the row if some acute toxicity data was found in the literature. "No data available" was added to the row if no acute toxicity data
was found in the literature.

Note 4:

For all listings above which contain the word "compounds" and for glycol ethers, the following applies:
Unless otherwise specified, these listings are defined as including any unique chemical substance
that contains the named chemical (i.e, antimony, arsenic, etc.) as part of that chemical’s infrastructure.

Note 5:

Chlorinated Dibenzo-P-Dioxins and Dibenzofurans: The cancer potency value for
2,3,7,8-tetrachlorodibenzo-p-dioxin was determined for the identification of chlorinated dioxins and
dibenzofurans as toxic air contaminants in 1986. At that time, the Board identified dibenzo-p-dioxins and
dibenzofurans chlorinated in the 2,3,7, and 8 positions and containing 4,5,6, or 7 chlorine atoms as toxic
air contaminants. Since 1986, International Toxicity Equivalency Factors (ITEFs) have been developed
which are used to evaluate the cancer risk due to exposure to samples containing mixtures of chlorinated
dibenzo-p-dioxins and dibenzofurans. ITEFs are numerical factors that express the toxicity of an individual
chlorinated dibenzo-p-dioxin or dibenzofuran relative to the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin.
ITEFs are listed for 16 chlorinated dibenzo-p-dioxins and dibenzofurans.

Note 6:

Diethanolamine: There is a 1997 draft report by the National Toxicology Program that shows evidence of
carcinogenic activity in mice. (This may result in a change of the cancer classification.)

Note 7:

Glycol Ethers: Includes mono- and di-ethers of ethylene glycol, diethylene glycol, and triethylene glycol
(R(OCH2CH2)n - OR' where 

n = 1,2 or 3

R = Alkyl or Aryl Groups

R' = R,H, or Groups Which, When Removed, Yield Glycol Ethers with the Structure; 

R (OCH2CH)n - OH. Polymers are excluded from the glycol category.

Note 8:

Inorganic Lead: Due to information on non-cancer health effects showing no identified threshold, no
Reference Exposure Level has been developed. However, guidelines for assessing noncancer health
impacts are currently being developed by ARB staff.

Note 9:

Polycyclic Organic Matter: Includes organic compounds with more than one benzene ring, and which
have a boiling point greater than or equal to 100 oC.

Note 10:

Benzo[a]pyrene: Potency Equivalency Factors (PEF) have been developed for 24 polycyclic aromatic
hydrocarbons (PAHs). Using benzo[a]pyrene as a reference compound, a weighting scheme for PAHs
was developed in the 1994 Air Resources Board document entitled, Benzo[a]pyrene as a Toxic Air
Contaminant. When a specific potency value is developed for a chemical, it should be used in place
of the PEF.

Note 11:

Cyanide Compounds: X'CN where X=H' or any other group where a formal dissociation may occur.
For example, KCN or Ca(CN)2...

Note 12:

Radionuclides: A type of atom which spontaneously undergoes radioactive decay.

Note 13:

Fine Mineral Fibers: Includes mineral fiber emissions from facilities manufacturing or processing glass,
rock, or slag fibers (or other mineral derived fibers) of average diameter 1 micrometer or less.

Note 14:

Environmental Tobacco Smoke: An AB 1807-type of health assessment for Environmental Tobacco Smoke
was conducted by the Office of Environmental Health Hazard Assessment (OEHHA) and was approved by
the Scientific Review Panel on June 19, 1997. The Air Resources Board accepted the report from OEHHA
on October 23,  1997 and subsequently forwarded to the Department of Health Services’ Tobacco Control
Program for appropriate action.

Note 15:

The OEHHA completed its inhalation cancer potency risk assessment on MTBE and the Scientific Review
Panel approved it at its November 1999 meeting.


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