Home Air OEHHA Acute, 8-hour and Chronic Reference Exposure Level (REL)s 

## A ir Toxicology and Epidemiolog y All OEHHA Acute, 8-hour and Chronic Refere nce Exposure Levels (chRELs) as of June 2014 Follow the links below to download document ation on the reference exposure levels. Footnotes: [1] REL types: A= acute, 8 = 8-hour, C = chronic. Exposure averaging time for acute RELs is 1 hour. For 8-hour RELs, the exposure averaging time is 8 hours, which may be repeated. Chronic RELs are designed to address continuous exposures for up to a lifetime: the exposure metric used is the annual average exposure. [2] Species used in key study for REL development: D = dog; Gb= gerbil; GP = guinea pig: H = human; Ha = hamster; M = mouse; Mk = monkey; R = rat; Rb = rabbit [3] These peer-reviewed chronic REL values were developed under the Toxic Air Contaminant (TAC) Program mandated by AB1807. [4] REL based on benchmark dose (BMC) approach. [5] REL developed using the revis ed methodology (OEHHA, 2008)]. OEHHA Acute, 8-hour and Chronic Refe rence Exposure Level (REL) Summary 1

Substance REL type

[1] Inhalation REL (ug/m3) Oral REL (ug/kg BW-day) Hazard Index Target Organs Species [2]

Acetaldehyde (75-07-0) A 470 [5] Eyes; respiratory system (sensory irritation) H 8 300 [4,5] Respiratory system R C 140 [4,5] Respiratory system R

Acrolein (107-02-8) A 2.5 [5] Eyes, respiratory system (sensory irritation) H 8 0.7 [5] Respiratory system R C 0.35 [5] Respiratory system R Acrylic Acid (79-10-7) A 6,000 Respiratory system; eyes R Acrylonitrile(107-13-1) C 5 [4] Respiratory system R 

### http://www.oehha.ca .gov/air/allrels.html

10/27 /201 4Ammonia (7664-41-7) A 3200 [4] Respiratory system; eyes H C 200 Respiratory system H

Arsenic(7440-38-2)& inorganic arsenic compounds (including arsine) A 0.20 [5] Development; cardiovascular system; nervous system M
8 0.015 [5] Development; cardiovascular system; nervous system; respiratory system; skin H

C 0.015 [5] 0.0035 [5] Inhalation & oral : Development; cardiovascular system; nervous system; respiratory system; skin H

Benzene (71-43-2) A 27 Developmental; Immune system; Hematologic system M
8 3 Hematologic system H C 3 Hematologic system H Benzyl Chloride (100-44-7) A 240 Respiratory system; eyes M, R Beryllium& beryllium compounds (7440-41-7) C 0.007 2.0 Inhalation: Respiratory system; immune system Oral: Alimentary system (Gastrointestinal tract) H

Butadiene (106-99-0) A 660 [4,5] Development M 8 9 [4,5] Reproductive system M C 2 [4,5] Reproductive system M Cadmium & cadmium compounds (7440- 43-9) C 0.02 0.5 Inhalation: Kidney; respiratory system Oral: kidney H

Carbon disulfide(75-15-0) A 6,200 Reproductive/ Development; nervous system R
C 800 [4] Nervous system; reproductive system H Carbon monoxide (630-08-0) A 23,000 Cardiovascular system H 

### http://www.oehha.ca .gov/air/allrels.html

10/27 /201 4Caprolactam (105-60-2) A 50 Eyes (sensory irritation) H 8 7 Respiratory system R C 2.2 Respiratory system R

Carbon tetrachloride(56-23-5) A 1,900 Alimentary system (liver); Reproductive/ Developmental; nervous system R

C 40 Alimentary and nervous systems; development GP Chlorinated dibenzo-p dioxins and dibenzofurans Unspeciated mixtures treated as 2,3,7,8-tetrachlorodibenz o-p-dioxin (1746-01-6) C 0.00004 1 x 10 -5 Inhalation and Oral: Alimentary (liver) reproductive, endocrine, respiratory, hematologic systems; development R

Chlorine(7782-50-5) A 210 Respiratory system; eyes H C 0.2 [4] Respiratory system R Chlorine dioxide (10049-04-4) C 0.6 Respiratory system R Chlorobenzene(108-90-7) C 1,000 Alimentary system (liver); kidney; reproductive system R

Chloroform (67-66-3) A 150 Reproductive/ Developmental; respiratory system; nervous system R

C 300 Alimentary system; kidney; development R Chloropicrin (76-06-2) A 29 Respiratory system; eyes M C 0.4 [4] Respiratory system M Chromic trioxide (as chromic acid mist) C 0.002 20 Inhalation: Respiratory system Oral: Hematologic system H Chromium (hexavalent ) (18540-29-9) & soluble hexavalent chromium compounds (except chromic trioxide) C 0.2 [4] 20 Inhalation: Respiratory system Oral: Hematologic system R Copper and compounds A 100 Respiratory system H 

### http://www.oehha.ca .gov/air/allrels.html

10/27 /201 4Cresol mixtures (1319-77-3) C 600 Nervous system R Dichlorobenzene (1,4-) (106-46-7) C 800 Nervous and respiratory; alimentary systems (liver); kidney R Dichloroethylene (1,1) (75-35-4) C 70 Alimentary system (liver) GP Diesel Exhaust C 5 [3] Respiratory system R Diethanolamine (111-42-2) C 3 Respiratory and hematologic systems R Dimethylformamide (N,N-) (68-12-2) C 80 Alimentary (liver) and respiratory systems H
Dioxane (1,4-) (123-91-1) A 3,000 Respiratory system; eyes H C 3,000 Alimentary system; kidney; cardiovascular system R
Epichlorohydrin (106-89-8) A 1,300 Respiratory system; eyes H C 3 Respiratory system; eyes R Epoxybutane (1,2-) (106-88-7) C 20 Respiratory system; cardiovascular system M Ethylbenzene (100-41-4) C 2,000 Alimentary system (liver); kidney; endocrine system; development M, R Ethyl chloride(75-00-3) C 30,000 Development; alimentary system (liver) M Ethylene dibromide (106-93-4) C 0.8 Reproductive system H Ethylene dichloride(107-06-2) C 400 Alimentary system (liver) R Ethylene glycol (107-21-1) C 400 Respiratory system; kidney; development H Ethylene glycol monobutyl ether (111-76-2) A 14,000 Respiratory system; eyes H Ethylene glycol monoethyl ether (110-80-5) A 370 Reproductive/ Development R C 70 Reproductive system; hemotologic system Rb 

### http://www.oehha.ca .gov/air/allrels.html

10/27 /201 4Ethylene glycol monoethyl ether acetate (111-15-9) A 140 Reproductive/ Development; nervous system R
C 300 Development Rb Ethylene glycol monomethyl ether (109-86-4) A 93 Reproductive/ Development R C 60 Reproductive system Rb Ethylene glycol monomethyl ether acetate (110-49-6) C 90 Reproductive system Rb Ethylene oxide(75-21-8) C 30 Nervous system R Fluorides (except Hydrogen Fluoride - listed below separately) C 13 [4] 40 Inhalation: Bone and teeth; respiratory system Oral: Bone and teeth H

Formaldehyde(50-00-0) A 55 [5] Eyes (Sensory irritation) H 8 9 [5] Respiratory system H C 9 [5] Respiratory system H Glutaraldehyde (111-30-8) C 0.08 [4] Respiratory system M Hexane (n-) (110-54-3) C 7000 Nervous system H Hydrazine (302-01-2) C 0.2 Alimentary syst em (liver); endocrine system Ha Hydrogen chloride(7647-01-0) A 2,100 Respiratory system; eyes H C 9 Respiratory system H Hydrogen cyanide(74-90-8) A 340 Nervous system H C 9 Nervous system; endocrine system; cardiovascular system H Hydrogen fluoride(7664-39-3) A 240 Respiratory system; eyes H C 14 [4] 40 Inhalation: Bone and teeth; respiratory system (See “fluorides” summary) H 

### http://www.oehha.ca .gov/air/allrels.html

10/27 /201 4Oral: Bone and teeth Hydrogen selenide(7783-07-5) A 5 Respiratory system; eyes GP Hydrogen sulfide(7783-06-4) A 42 Nervous system H C 10 Respiratory system M Isophorone(78-59-1) C 2,000 Development; alimentary system (liver) R, M Isopropanol (67-63-0) A 3,200 Eyes; respiratory system H C 7,000 Kidney; development R, M Maleic anhydride (108-31-6) C 0.7 [4] Respiratory system R,Ha, Mk Manganese (7439-96-5) & manganese compounds 8 0.17 [4,5] Nervous system H C 0.09 [4,5] Nervous system H
Mercury (7439-97-6) & inorganic mercury compounds A 0.6 [5] Nervous system; development R 8 0.06 [5] Nervous system; development; kidney H C 0.03 [5] 0.16 [5] Inhalation & Oral: Nervous system; development; kidney H

Methanol (67-56-1) A 28,000 Nervous system H C 4,000 [4] Development M
Methyl bromide (74-83-9) A 3900 Nervous system ; respiratory system; Reproductive/ development H
C 5 Respiratory system; nervous system; development R
Methyl chloroform (71-55-6) A 68,000 Nervous system H C 1000 Nervous system Gb Methylene chloride(75-09-2) A 14,000 H 

### http://www.oehha.ca .gov/air/allrels.html

10/27 /201 4Cardiovascular system; Nervous system C 400 Cardiovascular system; nervous system H Methylene dianiline (4,4’-) (101-77-9) C 20 Eyes; alimentary system (liver) GP Methylene diphenyl isocyanate (101-68-8) C 0.7 [4] Respiratory system R Methyl ethyl ketone(78-93-3) A 13,000 Respiratory system; eyes H Methyl isocyanate(624-83-9) C 1 Respiratory system; reproductive system R Methyl t- butyl ether (1634-04-4) C 8,000 Kidney; eyes; alimentary system (liver) R Naphthalene(91-20-3) C 9 Respiratory system H Nickel & nickel compounds (except nickel oxide for chronic inhalation exposures) (Inhalation concentrations as μg Ni/m3: oral dose as μg Ni/kg-day) A 0.2 [5] Immune system M 8 0.06 [5] Respiratory, immune systems R C 0.014 [5] 11 [5] Inhalation:Respiratory system; hematologic system Oral:Development R

Nickel oxide (1313-99-1) (Inhalation concentration as μg Ni/m3: oral dose as μg Ni/kg-day) C 0.02 [5] 11 [5] Inhalation:Respiratory system Oral:Development M R Nitric acid (7697-37-2) A 86 Respiratory system H Nitrogen dioxide(10102-44-0) A 470 Respiratory system H Ozone(10028-15-6) A 180 Respiratory system; eyes H Perchloroethylene (127-18-4) ( syn. Tetrachloroethylene) [3] A 20,000 Nervous system; respiratory system; eyes H C 35 Kidney; alimentary system (liver) M Phenol (108-95-2) A 5,800 Respiratory system; eyes H C 200 Alimentary system; cardiovascular system; kidney; nervous system R 

### http://www.oehha.ca .gov/air/allrels.html

10/27 /201 4Phosgene(75-44-5) A 4 Respiratory system R Phosphine(7803-51-2) C 0.8 Respiratory system; alimentary system (liver); nervous system; kidney; hematologic system M
Phosphoric acid (7664-38-2) C 7 [4] Respiratory system R Polychlorinated biphenyls (PCBs) Individual congeners ev aluated using TEF methodology, relative to as 2,3,7,8-tetrachlorodibenzo-p-dioxin (see Appendix C in the TSD for Cancer Potency Factors – online at: http://oehha.ca.gov/air/hot_spots/tsd052909.html C - - Inhalation & oral : Alimentary (liver) reproductive, endocrine, respiratory, hematologic systems; development R

Phthalic anhydride (85-44-9) C 20 Respiratory system H Propylene (115-07-1) C 3,000 Respiratory system R Propylene glycol monomethyl ether (107- 98-2) C 7,000 Alimentary system (liver) R
Propylene oxide(75-56-9) A 3,100 Respiratory system; eyes; reproductive/development H C 30 Respiratory system R Selenium and selenium compounds (other than hydrogen selenide) C 20 5 Inhalation & oral: Alimentary system (liver); cardiovascular system; nervous system H

Silica(crystalline, respirable) C 3 [4] Respiratory system H Sodium hydroxide(1310-93-2) A 8 Respiratory system; eyes; skin H Styrene (100-42-5) A 21,000 Respiratory system; eyes; reproductive/development H C 900 [4] Nervous system H Sulfates A 120 Respiratory system H Sulfur dioxide (7446-09-5) A 660 Respiratory system H Sulfuric acid (7664-93-9) [ & oleum, acute only ] A 120 Respiratory system H C 1 Respiratory system Mk 

### http://www.oehha.ca .gov/air/allrels.html

10/27 /201 4Flex Your Power Web site
Energy efficiency and conservation information. Find incentives/rebates, technical assistance, retailers, product guides, case studies and more. AMBER ALERT: Save a Child
AMBER ALERT empowers law enforcement, the media and the public to combat abduction by sending out immediate information. Toluene(108-88-3) A 37,000 Respiratory, nervous systems ; eyes reproductive/development H
C 300 Nervous system; respiratory system; development R Toluene diisocyanates (2,4- & 2,6-) C 0.07 Respiratory system H Trichloroethylene(79-01-6) C 600 Nervous system; eyes H Triethylamine (121-44-8) A 2,800 Nervous system; eyes H C 200 Eyes R Vanadium pentoxide (1314-62-1) A 30 Respiratory system; eyes H Vinyl acetate(108-05-4) C 200 Respiratory system R, M Vinyl chloride (75-01-4) A 180,000 Nervous system; respiratory system; eyes H Xylenes : technical mixture (1330-20-7) and o-xylene (95-47-6), m-xylene (108-38-3) and p-xylene (106-42-3) isomers. A 22000 Nervous & respiratory systems; eyes H C 700 Nervous & respiratory systems; eyes H 

### http://www.oehha.ca .gov/air/allrels.html

10/27 /201 4OEHHA is one of six agencies under the umbrella of the California Environmental Protection Agency(Cal/EPA). Air Resources Board | Cal Recycle | Department of Pesticide Regulation | Department of Toxic Substances Control Office of Environmental Health Hazard Assessment| State Water Resources Control Board Conditions of Use/Privacy Policy Copyright © 2007 OEHHA 

### http://www.oehha.ca .gov/air/allrels.html

10/27 /201 4