The Occupational Alliance for Risk Science (OARS) is an initiative to facilitate sharing of information with workers and occupational health and safety professionals. OARS provides a forum for information exchange about exposure guidance for chemical stressors, methods for improving occupational risk assessments, and training opportunities. The OARS serves as the home of exposure guide values, and related guideline documents, for chemical stressors. These guide values and supporting documentation related to worker and community exposure levels for chemical and physical agents and stressors are published by the OARS. OARS is managed by the Risk Science Center.
• OARS WEEL 2020 Roster has been added below Click Here.
• OARS WEEL documentation for Methoxytridecafluoroheptene isomers (MPHE).
The OARS WEEL committee has reviewed the OARS WEEL value for Methoxytridecafluoroheptene isomers (MPHE). The document is available for a 45-day public comment period. If you would like a copy of the public comment draft so as to submit comments, please send a request to Dr. Patricia McGinnis at mcginnis@tera.org. Comments are due by June 22, 2020.
• OARS WEEL documentation for 1,1,1,2,3,4,4,5,5,5-Decafluoropentane (HFC-4310mee). The OARS WEEL committee has reviewed the OARS WEEL value for 1,1,1,2,3,4,4,5,5,5-Decafluoropentane (HFC-4310mee). The document is available for a 45-day public comment period. If you would like a copy of the public comment draft so as to submit comments, please send a request to Dr. Patricia McGinnis at mcginnis@tera.org. Comments are due by June 22, 2020.
• OARS WEEL documentation. OARS WEEL documentation for 1,1,1,3,3,3-Hexamethyldisilazane (HDMZ) is posted as final.
• OARS WEEL documentation. OARS WEEL documentation for 1,1,2,2-Tetrafluoroethane (HFC-134) is posted as final.
• OARS WEEL documentation. OARS WEEL documentation for trans-1,1,1,4,4,4-Hexafluoro-2-butene (HFO-1336mzz-E) is posted as final.
• OARS WEEL documentation for 1,1,1,3,3,3-Hexamethyldisilazane (HMDZ). The OARS WEEL committee has reviewed the OARS WEEL value for 1,1,1,3,3,3-Hexamethyldisilazane (HMDZ). The document is posted here for a 45-day public comment period. Please submit comments to OARS WEEL at oarsweel@tera.org or fax to 513-488-1990 by May 20, 2018. OARS WEEL documentation for 1,1,2,2-Tetrafluoroethane (HFC-134).
• OARS WEEL documentation for 1,1,2,2-Tetrafluoroethane (HFC-134). The OARS WEEL committee has reviewed the OARS WEEL value for 1,1,2,2-Tetrafluoroethane (HFC-134). The document is posted here for a 45-day public comment period. Please submit comments to Dr. Patricia McGinnis at mcginnis@tera.org or fax to 513-488-1990 by May 17, 2018.
• OARS WEEL documentation. OARS WEEL documentation for Trifluoroiodomethane (CF3I) is posted as final.
• OARS WEEL documentation for trans-1,1,1,4,4,4-Hexafluoro-2-butene (HFO-1336mzz-E). The OARS WEEL committee has reviewed the OARS WEEL value for trans-1,1,1,4,4,4-Hexafluoro-2-butene. The document is posted here for a 45-day public comment period. Please submit comments to Dr. Patricia McGinnis at mcginnis@tera.org or fax to 513-488-1990 by April 7, 2018.
• OARS WEEL documentation for Trifluoroiodomethane (CF3I). The OARS WEEL committee has reviewed the OARS WEEL value for Trifluoroiodomethane. The document is posted here for a 45-day public comment period. Please submit comments to Dr. Patricia McGinnis at mcginnis@tera.org or fax to 513-488-1990 by March 25, 2018.
• The WEEL document for Octamethylcyclotetrasiloxane (D4) and Decamethylcyclopentasiloxane (D5) have been published in the Toxicology and Industrial Health journal. You can find the articles here: http://journals.sagepub.com/toc/tiha/33/1.
• OARS WEEL documentation. OARS WEEL documentation for HCFO-1224yd(Z) is final.
• OARS WEEL documentation. OARS WEEL documentation for Nitroguanidine (NQ) is final.
• OARS WEEL documentation. OARS WEEL documentation for Chlorosulfonic acid, p-Hydroxybenzoic acid, and Sodium Chloroacetate are final.
• OARS WEEL documentation. OARS WEEL documentation for Diisobutylene, Diethylene Glycol (DEG), Tetrachloropyridine, and Trifluoroethanol are final.
• OARS WEEL documentation for Melamine. OARS WEEL documentation for Melamine is final.
• The WEEL committee will hold their Spring meeting at the Royal Saint Charles Hotel in New Orleans on March 17 and 18, 2016 from 8:00 am to 5:00 pm. Please contact oarsweel@tera.org if you are interested in the meeting.
• OARS WEEL documentation for Butyraldehyde. The OARS WEEL value and documentation for Butyraldehyde is final.
• OARS WEEL documentati for Melamine. The OARS WEEL committee has revised the OARS WEEL values for Melamine. The documents are posted here for a 45-day public comment period. Please submit comments to Dr. Patricia McGinnis at mcginnis@tera.org or fax to 513-488-1990 by March 28, 2016.
• OARS WEEL documentation for 2-Chloropropane. The OARS WEEL value and documentation for
2-Chloropropane is final.
• OARS WEEL documentation. The OARS WEEL committee has reviewed the OARS WEEL values for Chlorosulfonic acid, p-Hydroxybenzoic acid, and Sodium Chloroacetate. The documents are posted here for a 45-day public comment period. Please submit comments to Dr. Patricia McGinnnis at mcginnis@tera.org or fax to 513-488-1990 by March 21, 2016.
• OARS WEEL documentation. The OARS WEEL committee has reviewed the OARS WEEL values for Diisobutylene, Diethylene Glycol (DEG), Tetrachloropyridine, and Trifluoroethanol. The documents are posted here for a 45-day public comment period. Please submit comments to Dr. Patricia McGinnis at mcginnis@tera.org or fax to 513-488-1990 by March 10, 2016.
NEWS ARCHIVES (pdf) Click Here
The OARS-WEEL Committee consists of volunteer experts dedicated to the science of setting occupational exposure levels. The Committee strives for a balance of toxicology and industrial hygiene professionals with a broad base of experience from industry, government, academia, and consulting services. Each member serves on the Committee solely in his/her individual capacity and not as a representative of his/her employer, organization and/or agency.
Chair: Janet Gould, PhD, DABT
Vice Chair: Ann Parker, MS
Secretary: Leslie Beyer, MS, DABT
Past Chair: Dan E. Arrieta, MS, PhD, DABT
Stacy Barnett, MS
Joel Bercu, PhD, MPH, DABT
Bill Brock, Ph.D., DABT, Fellow ATS
Courtney M. Callis, MPH, DABT
David Clapin, PhD, MPA, DABT, ERT
Patrick Coin, PhD
Michelle Deveau, MSc (A), ROH, CRSP
Doug Donahue, MS, DABT
Christine Glatt, PhD, DABT
Jessica Graham, PhD, DABT
Andrew A. “Tony” Havics, MS, CIH, PE
Sophie Jia, MD, PhD, DABT
Mark Korchinski, MSc (Tox), ERT, DABT
Emily Lent, PhD
Tom Lewandowski, PhD, DABT, ERT, ATS
Andrew Maier, PhD, CIH, DABT
Bob Nocco, MS, CIH
Patrick Owens, MS, CIH
James C. Rock, PhD, PE, CIH
Robert Roy, PhD, DABT
Karuna Sachdeva, PhD, DABT
Lawrence M. Segal, PhD, ERT
Robert Sloglund, PhD, DABT, CIH
Andrew Soiefer, PhD, DABT
Kenneth R. Still, PhD, FATS, CIH, CSP, CHMM
Henry J. Trochimowicz, ScD, DABT
Ann Tveit, PhD, DABT
Brittany Weldon, PhD
Occupational exposure limits (OELs) are developed for protection of healthy workers; they are not intended for the general public, which includes sensitive populations such as infants, the elderly, or the infirm. OELs are based on repeated daily exposures over a working lifetime. They are normally averaged over an 8-hour workday and serve to protect against acute and chronic health effects.
Click Here to download the PDF version of the table
| Substance | CAS | Source | 8-Hour TWA | Ceiling or Short-Term TWA | Last Revised |
| Acetone Cyanohydrin | 75-86-5 | AIHA | 2 ppm (skin) | 5 ppm (15 min, skin) | 1992 |
| Acetophenone | 98-86-2 | AIHA | 10 ppm | — | 2007 |
| Aldicarb | 116-06-3 | AIHA | 0.01 mg/m3 (skin) | — | 2009 |
| Allyl Isothiocyanate | 57-06-7 | AIHA | — | 1 ppm (15-min, skin, DSEN) | 1993 |
| Aminobenzoic Acid, para- | 150-13-0 | AIHA | 5 mg/m3 | — | 2001 |
| Aminotri (Methylenephosphonic Acid) | 6419-19-8 | AIHA | 10 mg/m3 | — | 2004 |
| Amyl Alcohol, n- | 71-41-0 | AIHA | 100 ppm | — | 2001 |
| Benzaldehyde | 100-52-7 | AIHA | 2 ppm | 4 ppm (15-min, DSEN) | 1998 |
| Benzenesulfonic acid, 5-chloro-2((2-Hydroxy-1-napthalenyl)-azo)-4-methyl, barium salt (2:1) | 5160-02-1 | AIHA | 1 mg/m3 | — | 2008 |
| Benzophenone | 119-61-9 | AIHA | 0.5 mg/m3 | — | 2003 |
| Benzoyl Chloride | 98-88-4 | AIHA | — | 5 ppm (ceiling, skin, DSEN) | 2008 |
| Benzyl Alcohol | 100-51-6 | AIHA | 10 ppm | — | 2008 |
| Butylcatechol, 4-tert- | 98-29-3 | AIHA | — | 2 mg/m3 (ceiling, skin, DSEN) | 2001 |
| Butyraldehyde | 123-72-8 | OARS | 25 ppm (75 mg/m3) | — | 2016 |
| Chloramphenicol | 56-75-7 | AIHA | 0.5 mg/m3 | — | 2008 |
| Chloroisopropyl)Ether, bis-(2- | 39638-92-9 | AIHA | 3 ppm | — | 2009 |
| Chloropropane, 2- | 75-29-6 | OARS | 50 ppm (161 mg/m3) | — | 2016 |
| Chlorosulfonic Acid | 7790-94-5 | OARS | — | — | 2016* |
| Chlorotrifluoroethylene | 79-38-9 | AIHA | 5 ppm | — | 2010 |
| Cumene Hydroperoxide | 80-15-9 | AIHA | 1 ppm (skin) | — | 2009 |
| Decabromodiphenyl Oxide | 1163-19-5 | AIHA | 5 mg/m3 | — | 2009 |
| Decamethylcyclopentasiloxane (D5) | 541-02-6 | OARS | 10 ppm | — | 2015 |
| Decene, 1- | 872-05-9 | AIHA | 100 ppm | — | 2000 |
| Dehydrolinalool | 29171-20-8 | AIHA | 2 ppm | — | 2007 |
| Diallylamine | 124-02-7 | AIHA | 1 ppm (skin) | — | 2009 |
| Dibromoneopentyl Glycol | 3296-90-0 | AIHA | 0.2 mg/m3 | — | 2010 |
| Dibutylamine | 111-92-2 | AIHA | — | 5 ppm (ceiling, skin) | 2003 |
| Dichlorophenol, 2,4- | 120-83-2 | AIHA | 1 ppm (skin*) | — | 2004 |
| Diethylbenzenes, mixed isomers | 25340-17-4 | AIHA | 5 ppm | — | 2005 |
| Diethylene Glycol | 111-46-6 | OARS | 10 mg/m3 | — | 2016 |
| Diethylene Glycol Monoethyl Ether | 111-90-0 | AIHA | 25 ppm | — | 1991 |
| Difluoroethane, 1,1- | 75-37-6 | AIHA | 1000 ppm | — | 2005 |
| Difluoroethane, 1-Chloro-1,1- | 75-68-3 | AIHA | 1000 ppm | — | 1994 |
| Difluoromethane | 75-10-5 | AIHA | 1000 ppm | — | 1997 |
| Diisobutylene | 25167-70-8 | OARS | 75 ppm (344 mg/m3 ) | — | 2016 |
| Dimethyl Ether | 115-10-6 | AIHA | 1000 ppm | — | 2010 |
| Dimethyl Sulfoxide | 67-68-5 | AIHA | 250 ppm | — | 2003 |
| Dimethyl Terephthalate | 120-61-6 | AIHA | 5 mg/m3 (total) | — | 2000 |
| Dimethyldichlorosilane | 75-78-5 | AIHA | — | 2 ppm (ceiling) | 2001 |
| Dimethylethylamine | 598-56-1 | AIHA | 1 ppm | 3 ppm | 2011 |
| Dimethyl-para-toluidine, n,n- | 99-97-8 | AIHA | 0.5 ppm | — | 2009 |
| Dinitroanisole, 2,4- (DNAN) | 119-27-7 | OARS | 0.1 mg/m3 (0.01 ppm) | — | 2014 |
| Dowtherm Q | 612-00-0, 68987-42-8 | AIHA | 7.8 mg/m3 | — | 2002 |
| Epoxybutane, 1,2- | 106-88-7 | AIHA | 2 ppm | — | 2003 |
| Erythromycin | 114-07-8 | AIHA | 3 mg/m3 | — | 2007 |
| Fluoroethane, 1,1-dichloro-1- | 1717-00-6 | AIHA | 500 ppm | 3000 ppm (5-min STEL) | 2008 |
| Furan | 110-00-9 | AIHA | Worker exposure by all routes should be minimalized to the fullest extent possible. | — | 1993 |
| GlycidylMethacrylate | 106-91-2 | AIHA | 0.5 ppm (skin, DSEN) | — | 2000 |
| Glyoxal | 107-22-2 | AIHA | 0.1 mg/m3 (DSEN) | — | 2000 |
| Hexadiene, 1,4- (mixed cis and trans) | 592-45-0 | AIHA | 10 ppm | — | 2009 |
| Hexafluoro-2-butene, cis-1,1,1,4,4,4- (HFO 1336mzz-Z) | 692-49-9 | OARS | 500 ppm (3350 mg/m3) | — | 2014 |
| Hexafluoro-2-butene, trans-1,1,1,4,4,4- (HFO 1336mzz-E) | 66711-86-2 | OARS | 400 ppm (2680 mg/m3) | — | 2018 |
| Hexafluoropropane, 1,1,1,3,3,3- | 690-39-1 | AIHA | 1000 ppm | — | 1998 |
| Hexamethyldisilazane (HMDZ) | 999-97-3 | OARS | 10 ppm | 50 ppm | 2018 |
| Hexamethylene Glycol | 629-11-8 | AIHA | 10 mg/m3 | — | 2011 |
| Hexanediamine, 1,6- | 124-09-4 | AIHA | 1 ppm | — | 2004 |
| Hexanediol Diacrylate | 13048-33-4 | AIHA | 1 mg/m3 (DSEN) | — | 1998 |
| Hexyl Alcohol, n- | 111-27-3 | AIHA | 40 ppm (eye irritation) | — | 2011 |
| HFE-7100 | 163702-07-6, 163702-08-7 |
AIHA | 750 ppm | — | 1999 |
| Hydroxybenzoic Acid, 4- | 99-96-7 | OARS | 5 mg/m3 | — | 2016 |
| Isobutyraldehyde | 78-84-2 | AIHA | 25 ppm | — | 2002 |
| Isocyanuric Acid | 108-80-5 | AIHA | 10 mg/m3 (total); 5 mg/m3 (respirable) |
— | 2005 |
| Isophthalic Acid | 121-91-5 | AIHA | 10 mg/m3 (total); 5 mg/m3 (respirable) |
— | 1991 |
| Isoprene | 78-79-5 | AIHA | 2 ppm | — | 2004 |
| Limonene, d- | 5989-27-5 | AIHA | 30 ppm | — | 1993 |
| Lithium Hydroxide | 1310-65-2 | AIHA | — | 1 mg/m3 (ceiling) | 1999 |
| Lithium Oxide | 12057-24-8 | AIHA | — | 1 mg/m3 (ceiling) | 1999 |
| Mancozeb | 8018-01-7 | AIHA | 1 mg/m3 (total, DSEN) | — | 2008 |
| Melamine | 108-78-1 | OARS | 3 mg/m3 | — | 2016 |
| Menthol | 1490-04-6 | OARS | 1 ppm | 3 ppm (15 min) | 2014 |
| Mercaptobenzothiazole, 2- | 149-30-4 | AIHA | 5 mg/m3 (skin, DSEN) | — | 2010 |
| Mercaptoethanol | 60-24-2 | AIHA | 0.2 ppm (skin) | — | 2002 |
| Methoxypropylamine, 3- | 5332-73-0 | AIHA | 5 ppm | 15 ppm (15 min) | 2009 |
| Methyl Ethyl Ketoxime | 96-29-7 | AIHA | 10 ppm (DSEN) | — | 1990 |
| Methyl-2-Pyrrolidone, n- | 872-50-4 | AIHA | 10 ppm (skin) | — | 2010 |
| Methyltrichlorosilane | 75-79-6 | AIHA | — | 1 ppm (ceiling) | 2001 |
| Monochloroacetic Acid | 79-11-8 | AIHA | 0.5 ppm (skin) | — | 2004 |
| Nitro-1,2,4-Triazol-5-One, 3- (NTO) | 932-64-9 | OARS | 2 mg/m3 | — | 2014 |
| Nitroguanidine, 1- (NQ) | 556-88-7 | OARS | 7 mg/m3 | — | 2016 |
| Octamethylcyclotetrasiloxane (D4) | 556-67-2 | OARS | 10 ppm | — | 2014 |
| Octanol, 1- | 111-87-5 | AIHA | 50 ppm | — | 2005 |
| Octene, 1- | 111-66-0 | AIHA | 75 ppm | — | 2000 |
| Pentaerythritol Triacrylate | 3524-68-3 | AIHA | 1 mg/m3 (DSEN) | — | 1999 |
| Pentafluoroethane, 1,1,1,2,2- | 354-33-6 | AIHA | 1000 ppm | — | 2009 |
| Pentafluoropropane, 1,1,1,3,3- | 460-73-1 | AIHA | 300 ppm | — | 2001 |
| Phosphono-1,2,4 butanetricarboxylic, 2-acid | 37971-36-1 | AIHA | 10 mg/m3 | — | 2006 |
| Picolines | 109-06-8, 108-99-6, 108-89-4 | AIHA | 2 ppm (skin) | 5 ppm (15-min, skin) | 1988 |
| Piperidine | 110-89-4 | AIHA | 1 ppm (skin) | — | 1996 |
| Polyethylene Glycols (MW > 200) | 25322-68-3 | AIHA | 10 mg/m3 | — | 2009 |
| Polypropylene Glycols | 25322-69-4 | AIHA | 10 mg/m3 | — | 1997 |
| Potassium Bromate | 7758-01-2 | AIHA | 0.1 mg/m3 | — | 2004 |
| Propargyl Bromide | 106-96-7 | AIHA | 0.1 ppm (skin) | — | 1997 |
| Propenoic Acid, isooctyl ester, 2- | 29590-42-9 | AIHA | 5 ppm | — | 2010 |
| Propionaldehyde | 123-38-6 | AIHA | 20 ppm | — | 2002 |
| Propylene Glycol | 57-55-6 | AIHA | 10 mg/m3 | — | 2004 |
| Propylene Glycol Monomethyl Ether Acetate | 108-65-6 | AIHA | 50 ppm | — | 2005 |
| Quinoline | 91-22-5 | AIHA | 0.001 ppm (skin) | — | 2006 |
| Sodium Chloroacetate | 3926-62-3 | OARS | 0.5 ppm (2.5 mg/m3 ) | — | 2016 |
| Sodium Hypochlorite | 7681-52-9 | AIHA | — | 2 mg/m3 (15 min) | 2010 |
| Tetrachloropyridine, 2,3,5,6- | 2402-79-1 | OARS | 5 mg/m3 | — | 2016 |
| Tetrachlorosilane | 10026-04-7 | AIHA | — | 1 ppm (ceiling) | 1999 |
| Tetraethylene Glycol Diacrylate | 17831-71-9 | AIHA | 1 mg/m3 (skin, DSEN) | — | 1981 |
| TetraethylenePentamine | 112-57-2 | AIHA | 5 mg/m3 (skin, DSEN) | — | 2004 |
| Tetrafluoroethane, 1,1,1,2- (HFC-134a) | 811-97-2 | AIHA | 1000 ppm | — | 2003 |
| Tetrafluoroethane, 1,1,2,2- (HFC-134) | 359-35-3 | OARS | 1000 ppm | — | 2018 |
| Tetrafluoroethane, 2-Chloro-1,1,1,2- | 2837-89-0 | AIHA | 1000 ppm | — | 2005 |
| Tetrafluoropropene, (Z)-1-Chloro-2,3,3,3- (HCFO-1224yd(Z)) | 111512-60-8 | OARS | 1000 ppm | — | 2017 |
| Tetrafluoropropene, 2,3,3,3,- (HFO-1234yf) | 754-12-1 | AIHA | 500 ppm | — | 2009 |
| Tetrafluoropropylene, 1,3,3,3- | 1645-83-6 | AIHA | 800 ppm | — | 2011 |
| Tetrahydrofurfuryl Alcohol | 97-99-4 | AIHA | 0.5 ppm (skin) | — | 1993 |
| Titanium Tetrachloride | 7550-45-0 | AIHA | 0.5 mg/m3 | — | 2009 |
| Toluene Diamine, 2,4- and mixed isomers | 95-80-7; 25376-45-8 | AIHA | 0.005 ppm (skin) | — | 2010 |
| Toluenesulfonyl Chloride, para- | 98-59-9 | AIHA | — | 5 mg/m3 (ceiling) | 2009 |
| trans-1-Chloro-3,3,3-trifluoropropylene (HCFO-1233zd(E)) | 102687-65-0 | OARS | 800 ppm | — | 2013 |
| Trichlorosilane | 10025-78-2 | AIHA | — | 0.5 ppm (ceiling) | 1998 |
| Triethoxysilane | 998-30-1 | AIHA | 0.05 ppm | — | 2000 |
| Triethylene Glycol Diacrylate | 1680-21-3 | AIHA | 1 mg/m3 (skin) | — | 1981 |
| Triethylenetetramine | 112-24-3 | AIHA | 1 ppm (skin) | — | 2009 |
| Triethylphosphate | 78-40-0 | AIHA | 7.45 mg/m3 | — | 2010 |
| Trifluoro-2,2-Dichloroethane, 1,1,1- | 306-83-2 | AIHA | 50 ppm | — | 2001 |
| Trifluoroethane, 1,1,1- | 420-46-2 | AIHA | 1000 ppm | — | 1996 |
| Trifluoroethanol, 2,2,2- | 75-89-8 | OARS | 0.3 ppm | — | 2016 |
| Trifluoroiodomethane (CF3I) | 2314-97-8 | OARS | 500 ppm | 1500 ppm | 2018 |
| Trimethoxysilane | 2487-90-3 | AIHA | 0.05 ppm | — | 2010 |
| Trimethylamine | 75-50-3 | AIHA | 1 ppm | — | 2005 |
| Trimethylchlorosilane | 75-77-4 | AIHA | — | 5 ppm (ceiling) | 2001 |
| Trimethylolpropane Triacrylate | 15625-89-5 | AIHA | 1 mg/m3 (skin) | — | 1981 |
| Trimethylolpropane Trimethacrylate | 3290-92-4 | AIHA | 1 mg/m3 (skin) | — | 1981 |
| Trisodium Phosphate | 7601-54-9 | AIHA | — | 5 mg/m3 (15 min) | 2009 |
| Urea | 57-13-6 | AIHA | 10 mg/m3 | — | 2007 |
| Vanillin | 121-33-5 | AIHA | 10 mg/m3 | — | 2009 |
| Vinylcyclohexene | 100-40-3 | AIHA | 1 ppm | — | 2009 |
| Vinyltrichlorosilane | 75-94-5 | AIHA | — | 1 ppm (ceiling) | 2002 |
*Value withdrawn
Substances Considered But Determined to Have an Inadequate Minimum Data Set:
Chlorine Monoxide
Methylene Butanedioic Acid
1,3-Pentadiene
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Phone: 513.542.7475 Fax: 513.488.1990
Email: tera@tera.org
