air toxics
Environmental Protection Agency's
Reference Concentrations (RfCs)
This ranking is based on EPA's Reference Concentration (RfC). A RfC is an estimate of a continuous inhalation exposure concentration to people (including sensitive subgroups) that is likely to be without risk of deleterious effects during a lifetime. An RfC is reported in milligrams of pollutant per cubic meter of air (mg/m 3 ).
The following are the pollutants in the 1999 Alaska Air Toxics Emission Inventory considered to be some of the most toxic for non-cancer effects as they correspond to the ten lowest reference concentrations.
Rank |
Chemical Name | RfC mg/m 3 |
Comments |
1 |
Chromium VI chromic acid mists and dissolved Cr (VI) aerosols |
0.000008 |
n/a |
2 |
Cadmium compounds |
0.00001 |
RfC from California Environmental Protection Agency |
2 |
Hexamethylene-1,6-Diisocyanate |
0.00001 |
n/a |
3 |
Acrolein |
0.00002 |
n/a |
3 |
Beryllium Compounds | 0.00002 |
n/a |
4 |
2-Chloroacetophenone |
0.00003 |
n/a |
4 |
Arsenic Compounds (inorganic including arsine) | 0.00003 |
RfC from California Environmental Protection Agency |
5 |
Arsine |
0.00005 |
n/a |
5 |
Manganese Compounds | 0.00005 |
n/a |
5 |
Nickel Compounds | 0.00005 |
RfC from California Environmental Protection Agency |
6 |
Chlorine |
0.00006 |
RfC from California Environmental Protection Agency |
7 |
2,4-Toluene Diisocyanate |
0.00007 |
RfC for mixture of Toluene 2,4- and 2,6-Diisocyanate |
7 |
Phosphorus | 0.00007 |
RfC from California Environmental Protection Agency |
8 |
Chromium VI Particulates |
0.0001 |
n/a |
9 |
1,2-Dibromo-3-Chloropropane | 0.0002 |
n/a |
9 |
Antimony Compounds |
0.0002 |
RfC for Antimony Trioxide |
9 |
Ethylene Dibromide (Dibromoethane) |
0.0002 |
n/a |
9 |
Hexachlorocyclopentadiene | 0.0002 |
n/a |
9 |
Hydrazine |
0.0002 |
RfC from California Environmental Protection Agency |
10 |
Lindane (all isomers) |
0.0003 |
RfC from California Environmental Protection Agency |
10 |
Elemental Mercury |
0.0003 |
n/a |
10 |
Phosgene |
0.0003 |
RfC from California Environmental Protection Agency |
10 |
Phosphine |
0.0003 |
n/a |
The following pollutants in the 1999 Alaska Air Toxics Emission Inventory also have RfCs:
| Dichlorvos | Methylene diphenyl diisocyante (MDI) | Acrylamide |
| Allyl Chloride | Chlordane | Acrylic Acid |
| Aniline | Epichlorohydrin (1-Chloro-2,3-epoxypropane) | Methyl Isocyanate |
| Acrylonitrile |
Maleic Anhydride | Nitrobenzene |
| Cyanide Compounds | Ethylene Thiourea | Hexachlorobenzene |
| Naphthalene | Vinyl Bromide | Cresols/Cresylic Acid (isomers and mixture) |
| Propylene Dichloride (1,2-Dichloropropane) |
Ethylene Oxide | Methyl Bromide(Bromomethane) |
| Phenol |
Styrene Oxide | 2,4-Dinitrotoluene |
| Chloroprene | Triethylamine | 1,3-Butadiene |
| Acetaldehyde |
Benzidine | Bis(2-ethylhexyl)phthalate (DEHP) |
| Isophorone | 1,2-Epoxybutane | 1,3-Dichloropropene |
| 2-Nitropropane |
4,4'-Methylenedianiline | Chlorobenzene |
| Diethanolamine | 2-Methoxyethanol | 2-Butoxyethanol |
| Hydrochloric Acid | Elemental Selenium | Vinylidene Chloride (1,1-Dichloroethylene) |
| Dimethyl Formamide |
Hydrogen Fluoride (Hydrofluoric acid) | Propylene Oxide |
| Carbon Tetrachloride | Acetonitrile | Benzene (including benzene from gasoline) |
| Hexachloroethane | Methyl Isobutyl Ketone (Hexone) | Hexachlorobutadiene |
| Methylchloride (Chloromethane) |
Pentachlorophenol | Vinyl Chloride |
| Phthalic Anhydride | 1,2,4-Trichlorobenzene | 2-Ethoxyethanol |
| Hexane | Vinyl acetate | Cumene |
| Chloroform |
1,1,2-Trichloroethane | Toluene |
| Ethylene dichloride (1,2-Dichloroethane) |
Ethylene Glycol | Carbon Disulfide |
| Ethylidene dichloride (1,1-Dichloroethane) | Trichloroethylene | 1,4-Dichlorobenzene(p) |
| Ethyl Benzene | Methyl Methacrylate | Methyl Ethyl Ketone (2-Butanone) |
| Styrene | Methyl Chloroform (1,1,1-Trichloroethane) | Methyl Tert Butyl Ether |
| Methylene | 1,4-Dioxane (1,4-Diethyleneoxide) | Ethyl Chloride (Chloroethane) |
| Methanol | Methylene chloride (Dichloromethane) |
To explore the possible health effects of these and other pollutants, please visit the following internet sites:
- http://www.epa.gov/iris/index.html - The Environmental Protection Agency's list of non-cancer and cancer risk values for many pollutants.
- http://www.atsdr.cdc.gov/mrls.html - The Agency for Toxic Substances and Disease Registry list of pollutants and corresponding Minimum Risk Levels.
- http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?HSDB - The National Institutes of Health, National Library of Medicine's toxicology data file focusing on the toxicology of potentially hazardous chemicals.
- http://www.epa.gov/ttn/atw/hapindex.html - The Environmental Protection Agency's list of hazardous air pollutants, including summaries of uses, sources and potential health effects.
- http://www.atsdr.cdc.gov/toxfaq.html - The Agency for Toxic Substances and Disease Registry list of Frequently Asked Questions about contaminants found at Hazardous Waste Sites.
