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Searches using filters for organ/system affected are limited to effects (or tumor sites) used to derive the RfD, RfC, oral slope factor, or inhalation unit risk. Other effects associated with chemicals in the IRIS database that were not used as the basis for a toxicity value are not searchable with organ/system filters. IRIS Advanced Search searches only final IRIS assessments; to look for information on draft assessments, see Quick Check: Assessments in Development. Additional information can be downloaded below by clicking on the “Export to Excel” feature.
RfC Toxicity Values
| ROW | CHEMICAL NAME | CASRN | PRINCIPAL CRITICAL EFFECT SYSTEM | PRINCIPAL CRITICAL DESCRIPTION | PRINCIPAL STUDY | STUDY CITATION | EXPERIMENTAL DOSE TYPE | POD VALUE | RFC VALUE | UNCERTAINTY FACTOR | MODIFYING FACTOR | STUDY CONFIDENCE | DATA CONFIDENCE | OVERALL CONFIDENCE | DOSE TYPE | DURATION |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Acetaldehyde | 75-07-0 | Nervous, Respiratory | Degeneration of olfactory epithelium | Short-term rat inhalation studies | Appleman et al., 1986 1982 | No Observable Adverse Effect Level | 8.7 mg/m3 | 0.009 mg/m3 | 1000 | 1 | Medium | Low | Low | Threshold | Chronic |
| 2 | Acetonitrile | 75-05-8 | Other | Mortality | Mouse subchronic/chronic inhalation studies | NTP, 1996 | No Observable Adverse Effect Level | 60.0 mg/m3 | 0.06 mg/m3 | 100 | 10 | Medium | Medium | Medium | Threshold | Chronic |
| 3 | Acrolein | 107-02-8 | Respiratory | Nasal lesions | Subchronic rat inhalation study | Feron et. al., 1978 | Lowest Observable Adverse Effect Level | 0.02 mg/m3 | 2e-05 mg/m3 | 1000 | 1 | Medium | Low/Medium | Medium | Threshold | Chronic |
| 4 | Acrylamide | 79-06-1 | Nervous | Degenerative nerve changes | Chronic rat study | Johnson et al. 1986 | Human Equivalent Concentration | 0.18 mg/m3 | 0.006 mg/m3 | 30 | 1 | Medium/High | Low/Medium | Medium | Threshold | Chronic |
| 5 | Acrylic acid | 79-10-7 | Nervous, Respiratory | Degeneration of the nasal olfactory epithelium | Mouse subchronic inhalation study | Miller et al., 1981a | Lowest Observable Adverse Effect Level | 0.33 mg/m3 | 0.001 mg/m3 | 300 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 6 | Acrylonitrile | 107-13-1 | Respiratory | Degeneration and inflammation of nasal respiratory epithelium; hyperplasia of mucous secreting cells | Rat 2-year inhalation study | Quast et al., 1980 | Lowest Observable Adverse Effect Level | 1.9 mg/m3 | 0.002 mg/m3 | 1000 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 7 | Allyl chloride | 107-05-1 | Nervous | Functional and histological peripheral neurotoxicity | Rabbit subchronic inhalation study | Lu et al., 1982 | No Observable Adverse Effect Level | 3.6 mg/m3 | 0.001 mg/m3 | 3000 | 1 | Low | Low | Low | Threshold | Chronic |
| 8 | Ammonia | 7664-41-7 | Respiratory | Decreased lung function and respiratory symptoms | Occupational epidemiology studies | Holness et al. (1989), supported by Rahman et al. (2007), Ballal et al. (1998), and Ali et al. (2001) | No Observable Adverse Effect Level | 4.9 mg/m3 | 0.5 mg/m3 | 10 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 9 | Aniline | 62-53-3 | Hematologic | Methemoglobin increase, spleen toxicity | 20-26 week inhalation rat, guinea pig and mouse study | Oberst et al., 1956 | No Observable Adverse Effect Level | 3.4 mg/m3 | 0.001 mg/m3 | 3000 | 1 | Low | Low | Low | Threshold | Chronic |
| 10 | Antimony trioxide | 1309-64-4 | Respiratory | Pulmonary toxicity, chronic interstitial inflammation | Rat 1-year inhalation toxicity study | Newton et al., 1994 | Benchmark Concentration | 0.074 mg/m3 | 0.0002 mg/m3 | 300 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 11 | Arsine | 7784-42-1 | Hematologic, Immune | Increased hemolysis, abnormal RBC morphology, and increased spleen weight | 13-week rat and mouse and 28-day hamster inhalation study | Blair et al., 1990a,b | No Observable Adverse Effect Level | 0.014 mg/m3 | 5e-05 mg/m3 | 300 | 1 | High | Medium | Medium | Threshold | Chronic |
| 12 | Benzene | 71-43-2 | Immune | Decreased lymphocyte count | Human occupational inhalation study | Rothman et. al., 1996 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 8.2 mg/m3 | 0.03 mg/m3 | 300 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 13 | Benzo[a]pyrene (BaP) | 50-32-8 | Reproductive | Reduced ovulation rate and ovary weight | Premating study in rats (14 d) | Archibong et al. (2012) | Lowest Observable Adverse Effect Level | 0.0091 mg/m3 | 3e-06 mg/m3 | 3000 | 1 | None | None | Low/Medium | Threshold | Chronic |
| 14 | Benzo[a]pyrene (BaP) | 50-32-8 | Developmental | Decreased embryo/fetal survival | Developmental toxicity study in rats (GDs 11−20) | Archibong et al. (2002) | Lowest Observable Adverse Effect Level | 0.0046 mg/m3 | 2e-06 mg/m3 | 3000 | 1 | Low/Medium | Low | Low/Medium | Threshold | Chronic |
| 15 | Beryllium and compounds | 7440-41-7 | Immune, Respiratory | Beryllium sensitization and progression to CBD | Occupational study | Kreiss et al., 1996 | Lowest Observable Adverse Effect Level | 0.0002 mg/m3 | 2e-05 mg/m3 | 10 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 16 | Bromobenzene | 108-86-1 | Hepatic | Hepatocellular cytomegaly in female B6C3F1 mice | 13-week inhalation study | NTP (1985d) | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 63.0 mg/m3 | 0.06 mg/m3 | 1000 | 1 | Medium | Low/Medium | Low/Medium | None | Chronic |
| 17 | Bromobenzene | 108-86-1 | Hepatic | Hepatocellular cytomegaly in female B6C3F1 mice | 13-week inhalation study | NTP (1985d) | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 63.0 mg/m3 | 0.2 mg/m3 | 300 | 1 | Medium | Medium | Medium | None | Subchronic |
| 18 | Bromomethane | 74-83-9 | Nervous, Respiratory | Degenerative and proliferative lesions of the olfactory epithelium of the nasal cavity | Rat 29-month inhalation study | Reuzel et al., 1987, 1991 | Lowest Observable Adverse Effect Level | 0.48 mg/m3 | 0.005 mg/m3 | 100 | 1 | Medium | High | High | Threshold | Chronic |
| 19 | 1,3-Butadiene | 106-99-0 | Reproductive | Ovarian atrophy | 2-year mouse inhalation study | NTP, 1993 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 1.98 mg/m3 | 0.002 mg/m3 | 1000 | 1 | High | High | Medium | Threshold | Chronic |
| 20 | Carbon disulfide | 75-15-0 | Nervous | Peripheral nervous system dysfunction | Occupational study | Johnson et al., 1983 | Benchmark Concentration | 19.7 mg/m3 | 0.7 mg/m3 | 30 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 21 | Carbon tetrachloride | 56-23-5 | Hepatic | Fatty changes in the liver | Chronic inhalation toxicity study in rats | Nagano et al., 2007b, JBRC, 1998 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 14.3 mg/m3 | 0.1 mg/m3 | 100 | 1 | High | Medium | Medium | Threshold | Chronic |
| 22 | Cerium Oxide and Cerium Compounds | 1306-38-3 | Respiratory | Increased incidence of alveolar epithelial hyperplasia in the lungs of male and female rats | Subchronic inhalation study | BRL, 1994 (unpublished study) | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 0.86 mg/m3 | 0.0009 mg/m3 | 1000 | 1 | Medium | Low | Low | Benchmark | Chronic |
| 23 | Chlordane (Technical) | 12789-03-6 | Hepatic | Hepatic effects | Rat subchronic inhalation study | Khasawinah et al., 1989a | No Observable Adverse Effect Level | 0.65 mg/m3 | 0.0007 mg/m3 | 1000 | 1 | Medium | Low | Low | Threshold | Chronic |
| 24 | Chlorine dioxide | 10049-04-4 | Cardiovascular, Respiratory | Vascular congestion and peribronchial edema | 60-day rat inhalation study | Paulet and Desbrousses, 1972 | Lowest Observable Adverse Effect Level | 0.64 mg/m3 | 0.0002 mg/m3 | 3000 | 1 | Low | Low | Low | Threshold | Chronic |
| 25 | 1-Chloro-1,1-difluoroethane | 75-68-3 | Other | No adverse effects | 2-year rat inhalation study | Seckar et al., 1986 | No Observable Adverse Effect Level | 14710.0 mg/m3 | 50.0 mg/m3 | 300 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 26 | 2-Chloroacetophenone | 532-27-4 | Respiratory | Squamous hyperplasia of the nasal respiratory epithelium | Chronic rat inhalation study | NTP, 1990 | Lowest Observable Adverse Effect Level | 0.03 mg/m3 | 3e-05 mg/m3 | 1000 | 1 | Medium | Low | Low | Threshold | Chronic |
| 27 | Chlorodifluoromethane | 75-45-6 | Endocrine, Urinary | Increased kidney, adrenal and pituitary weights | Chronic rat inhalation study | Tinston et al., 1981a | No Observable Adverse Effect Level | 5260.0 mg/m3 | 50.0 mg/m3 | 100 | 1 | High | Medium | Medium | Threshold | Chronic |
| 28 | Chloroprene | 126-99-8 | Immune, Nervous, Respiratory | Increase in incidence of olfactory atrophy, alveolar hyperplasia, and splenic hematopoietic proliferation in male F344/N rats, female F344/N rats, and female B6C3F1 mice, respectively | 2-year chronic inhalation study | NTP, 1998 | Benchmark Dose based on the LED10 (Lowest Effective Dose) | 2.0 mg/m3 | 0.02 mg/m3 | 100 | 1 | High | Medium/High | Medium/High | Threshold | Chronic |
| 29 | Chromium(VI) | 18540-29-9 | Respiratory | Ulcerated nasal septum in humans | None | None | Lowest Observable Adverse Effect Level | 0.0034 mg/m3 | 3e-05 mg/m3 | 100 | None | None | None | Medium | None | Chronic |
| 30 | Cumene | 98-82-8 | Endocrine, Urinary | Increased kidney weights in female rats and adrenal weights in male and female rats | Rat 13-week inhalation study | Cushman et al., 1995 | No Observable Adverse Effect Level | 435.0 mg/m3 | 0.4 mg/m3 | 1000 | 1 | High | Medium | Medium | Threshold | Chronic |
| 31 | Cyclohexane | 110-82-7 | Developmental | Reduced pup weights in the F1 and F2 generations | Rat, 2-generation reproductive/developmental toxicity study | DuPont HLR, 1997a | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 1822.0 mg/m3 | 6.0 mg/m3 | 300 | 1 | High | Low/Medium | Low/Medium | Threshold | None |
| 32 | 1,2-Dibromo-3-chloropropane (DBCP) | 96-12-8 | Reproductive | Testicular effects | 13-week subchronic rabbit inhalation study | Rao et al., 1982 | No Observable Adverse Effect Level | 0.17 mg/m3 | 0.0002 mg/m3 | 1000 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 33 | 1,2-Dibromoethane | 106-93-4 | Respiratory | Nasal inflammation | Mouse chronic inhalation study | NTP, 1982 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 2.8 mg/m3 | 0.009 mg/m3 | 300 | 1 | Medium | Medium | Medium | Benchmark | Chronic |
| 34 | 1,4-Dichlorobenzene | 106-46-7 | Hepatic | Increased liver weights in P1 males | Rat multigeneration reproductive study | Chlorobenzene Producers Assn., 1986 | No Observable Adverse Effect Level | 75.0 mg/m3 | 0.8 mg/m3 | 100 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 35 | 1,1-Dichloroethylene (1,1-DCE) | 75-35-4 | Hepatic | Liver toxicity (fatty change) | Rat chronic inhalation study | Quast et al., 1986 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 6.9 mg/m3 | 0.2 mg/m3 | 30 | 1 | High | Medium | Medium | Threshold | Chronic |
| 36 | Dichloromethane | 75-09-2 | Hepatic | Hepatic effects (hepatic vacuolation) | 2-Year rat inhalation bioassay | Nitschke et al. (1988a) | Benchmark Dose based on the LED10 (Lowest Effective Dose) | 17.2 mg/m3 | 0.6 mg/m3 | 30 | 1 | High | Medium/High | Medium/High | None | Chronic |
| 37 | 1,2-Dichloropropane | 78-87-5 | Respiratory | Hyperplasia of the nasal mucosa | Rat 13-week inhalation study | Nitschke et al., 1988 | Lowest Observable Adverse Effect Level | 1.3 mg/m3 | 0.004 mg/m3 | 300 | 1 | High | Medium | Medium | Threshold | None |
| 38 | 1,3-Dichloropropene | 542-75-6 | Respiratory | Hypertrophy/ hyperplasia of the nasal respiratory epithelium | Chronic inhalation study in B6C3F1 mice | Lomax et al., 1989 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 0.72 mg/m3 | 0.02 mg/m3 | 30 | 1 | High | High | High | Threshold | Chronic |
| 39 | Dichlorvos | 62-73-7 | Nervous | Decreased brain cholinesterase activity | Carworth Farm E strain rat chronic inhalation study | Blair et al., 1976 | No Observable Adverse Effect Level | 0.05 mg/m3 | 0.0005 mg/m3 | 100 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 40 | Diesel engine exhaust | None | Respiratory | Pulmonary inflammation and histopathology | Rat chronic inhalation study | Ishinishi et. al., (1988) | No Observable Adverse Effect Level | 0.144 mg/m3 | 0.005 mg/m3 | 30 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 41 | 1,1-Difluoroethane | 75-37-6 | Other | No adverse effects observed | 2-year inhalation study | McAlack and Schneider, 1982 | No Observable Adverse Effect Level | 12051.0 mg/m3 | 40.0 mg/m3 | 300 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 42 | N,N-Dimethylformamide | 68-12-2 | Hepatic | Digestive disturbances and minimal hepatic changes suggestive of liver abnormalities | Human occupational studies | Cirla et al., 1984; Catenacci et al., 1984 | Lowest Observable Adverse Effect Level | 7.9 mg/m3 | 0.03 mg/m3 | 300 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 43 | 1,4-Dioxane | 123-91-1 | Nervous, Respiratory | Atrophy and respiratory metaplasia of the olfactory epithelium | Chronic inhalation male rat study | Kasai et al. 2009 | Lowest Observable Adverse Effect Level | 32.2 mg/m3 | 0.03 mg/m3 | 1000 | 1 | Medium | Medium | Medium | None | Chronic |
| 44 | Epichlorohydrin | 106-89-8 | Respiratory | Changes in the nasal turbinates | Rat and mouse 90-day inhalation study | Quast et al., 1979a | No Observable Adverse Effect Level | 0.36 mg/m3 | 0.001 mg/m3 | 300 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 45 | 1,2-Epoxybutane (EBU) | 106-88-7 | Respiratory | Degenerative lesions of the nasal cavity | 2-year mouse inhalation study | NTP, 1988 | Lowest Observable Adverse Effect Level | 4.8 mg/m3 | 0.02 mg/m3 | 300 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 46 | 2-Ethoxyethanol | 110-80-5 | Hematologic, Reproductive | Decreased testis weight, seminiferous tubule degeneration and decreased hemoglobin | New Zealand White Rabbit subchronic toxicity study | Barbee et al., 1984 | No Observable Adverse Effect Level | 68.0 mg/m3 | 0.2 mg/m3 | 300 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 47 | Ethyl Tertiary Butyl Ether (ETBE) | 637-92-3 | Urinary | Increased absolute kidney weight in female rats | 2-year inhalation study in male and female F344 rats | Saito et al., 2013; JPEC, 2010b | No Observable Adverse Effect Level | 1110.0 mg/m3 | 40.0 mg/m3 | 30 | 1 | Medium | High | Medium | Threshold | Chronic |
| 48 | Ethyl chloride | 75-00-3 | Developmental, Musculoskeletal | Delayed fetal ossification | Mouse developmental inhalation study | Scortichini et al., 1986 | No Observable Adverse Effect Level | 4000.0 mg/m3 | 10.0 mg/m3 | 300 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 49 | Ethylbenzene | 100-41-4 | Developmental | Developmental toxicity | Rat and rabbit developmental inhalation studies | Andrew et al., 1981; Hardin et al., 1981 | No Observable Adverse Effect Level | 434.0 mg/m3 | 1.0 mg/m3 | 300 | 1 | Low | Low | Low | Threshold | Chronic |
| 50 | Ethylene glycol monobutyl ether (EGBE) (2-Butoxyethanol) | 111-76-2 | Hematologic | Hemosiderin deposition in the liver | Chronic (rat and mouse) inhalation study | NTP (2000) | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 16.0 mg/m3 | 1.6 mg/m3 | 10 | 1 | High | Medium/High | Medium/High | Threshold | Chronic |
| 51 | Formaldehyde | 50-00-0 | Respiratory | Decreased pulmonary function, prevalence of current asthma or degree of asthma control, and allergic conditions in children (See Note) | None | None | None | None | 0.007 mg/m3 | None | None | None | None | High | None | Chronic |
| 52 | Hexachlorocyclopentadiene (HCCPD) | 77-47-4 | Respiratory | Suppurative inflammation of the nose | Chronic inhalation study in B6C3F1 mice | NTP, 1994 | No Observable Adverse Effect Level | 0.024 mg/m3 | 0.0002 mg/m3 | 100 | 1 | High | Medium | Medium | Threshold | Chronic |
| 53 | Hexachloroethane | 67-72-1 | Nervous | Neurotoxicity (tremors and ruffled pelt) | 6-week subchronic inhalation study, male and female Sprague-Dawley rats | Weeks et al., 1979 | No Observable Adverse Effect Level | 83.0 mg/m3 | 0.03 mg/m3 | 3000 | 1 | Low | Low | Low | Threshold | Chronic |
| 54 | 1,6-Hexamethylene diisocyanate | 822-06-0 | Nervous, Respiratory | Degeneration of olfactory epithelium | Rat chronic inhalation study | Mobay, Inc., 1989 | No Observable Adverse Effect Level | 0.001 mg/m3 | 1e-05 mg/m3 | 100 | 1 | High | Medium | Medium | Threshold | Chronic |
| 55 | n-Hexane | 110-54-3 | Nervous | Peripheral neuropathy (decreased MCV at 12 weeks) | Rat subchronic inhalation study | Huang et al., 1989 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 215.0 mg/m3 | 0.7 mg/m3 | 300 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 56 | 2-Hexanone | 591-78-6 | Nervous | Motor conduction velocity of the sciatic-tibial nerve | Subchronic inhalation study in monkeys | Johnson et al., 1977 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 90.0 mg/m3 | 0.03 mg/m3 | 3000 | 1 | Medium | Low | Low | Benchmark | Chronic |
| 57 | Hydrogen Cyanide and Cyanide Salts | Various | Endocrine | Thyroid enlargement and altered iodide uptake | Epidemiology study | El Ghawabi et al., 1975 | Lowest Observable Adverse Effect Level | 2.5 mg/m3 | 0.0008 mg/m3 | 3000 | 1 | Medium | Low/Medium | Low/Medium | Threshold | Chronic |
| 58 | Hydrogen chloride | 7647-01-0 | Respiratory | Hyperplasia of nasal mucosa larynx and trachea | Rat chronic inhalation study | Sellakumar et al., 1994; Albert et al., 1982 | Lowest Observable Adverse Effect Level | 6.1 mg/m3 | 0.02 mg/m3 | 300 | 1 | Low | Low | Low | Threshold | Chronic |
| 59 | Hydrogen sulfide | 7783-06-4 | Nervous, Respiratory | Nasal lesions of the olfactory mucosa | Rat Subchronic Inhalation Study | Brenneman et. al., 2000 | No Observable Adverse Effect Level | 0.64 mg/m3 | 0.002 mg/m3 | 300 | 1 | Medium | Medium/High | Medium/High | Threshold | Chronic |
| 60 | Libby Amphibole Asbestos | 1318-09-8 | Respiratory | Localized pleural thickening | Occupational epidemiology study | Rohs et al. (2008) | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 0.026 fiber/cc | 9e-05 fiber/cc | 300 | 1 | Medium | Medium | Medium | None | Chronic |
| 61 | Manganese | 7439-96-5 | Nervous | Impairment of neurobehavioral function | Occupational exposure to manganese dioxide | Roels et al., 1992 | Lowest Observable Adverse Effect Level | 0.05 mg/m3 | 5e-05 mg/m3 | 1000 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 62 | Mercury, elemental | 7439-97-6 | Nervous | Hand tremor; increases in memory disturbances; slight subjective and objective evidence of autonomic dysfunction | Human occupational inhalation studies | Fawer et al., 1983; Piikivi and Tolonen, 1989; Piikivi and Hanninen, 1989; Piikivi, 1989; Ngim et al., 1992; Liang et al., 1993 | Lowest Observable Adverse Effect Level | 0.009 mg/m3 | 0.0003 mg/m3 | 30 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 63 | Methanol | 67-56-1 | Developmental, Nervous | Reduced brain weight in rat pups at 6 weeks of age | Male Sprague-Dawley rats, Developmental inhalation exposure through gestation and 3, 6 or 8 weeks postnatal | NEDO (1987) | Benchmark Dose based on the LED10 (Lowest Effective Dose) | 858.0 mg-hr/L | 20.0 mg/m3 | 100 | 1 | High | Medium | Medium/High | None | Chronic |
| 64 | 2-Methoxyethanol | 109-86-4 | Reproductive | Testicular effects | Subchronic inhalation studies in male New Zealand White Rabbits and Sprague-Dawley rats | Miller et al., 1983 | No Observable Adverse Effect Level | 17.0 mg/m3 | 0.02 mg/m3 | 1000 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 65 | Methyl chloride | 74-87-3 | Nervous | Cerebellar lesions | Mouse 11-day continuous inhalation study | Landry et al., 1983, 1985 | No Observable Adverse Effect Level | 94.6 mg/m3 | 0.09 mg/m3 | 1000 | 1 | High | Medium | Medium | Threshold | Chronic |
| 66 | Methyl ethyl ketone (MEK) | 78-93-3 | Developmental, Musculoskeletal | Developmental toxicity (skeletal variations) | Mouse developmental study | Schwetz et al., 1991 | Lowest Effect Concentration | 1517.0 mg/m3 | 5.0 mg/m3 | 300 | 1 | High | Medium | Medium | Threshold | Chronic |
| 67 | Methyl isobutyl ketone (MIBK) | 108-10-1 | Developmental, Musculoskeletal | Reduced fetal body weight, skeletal variations, and increased fetal death in mice, and skeletal variations in rats. | Rat and mouse developmental inhalation study | Tyl et. al., 1987 | No Observable Adverse Effect Level | 1026.0 mg/m3 | 3.0 mg/m3 | 300 | 1 | Medium | Low/Medium | Low/Medium | Threshold | Chronic |
| 68 | Methyl methacrylate | 80-62-6 | Nervous, Respiratory | Degeneration/ atrophy of olfactory epithelium (male rats) | Rat chronic inhalation study | Hazelton Laboratories 1979a Lomax, 1992 Lomax et al., 1997 | Benchmark Concentration | 7.2 mg/m3 | 0.7 mg/m3 | 10 | 1 | High | Medium/High | Medium/High | Threshold | Chronic |
| 69 | Methyl tert-butyl ether (MTBE) | 1634-04-4 | Hepatic, Ocular, Other, Urinary | Increased absolute and relative liver and kidney weights and increased severity of spontaneous renal lesions (females), increased prostration (females), and swollen periocular tissue (males and females) | Chronic rat 24-month inhalation study | Chun et al., 1992 | No Observable Adverse Effect Level | 259.0 mg/m3 | 3.0 mg/m3 | 100 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 70 | Methylene Diphenyl Diisocyanate (monomeric MDI) and polymeric MDI (PMDI) | 101-68-8 | Nervous, Respiratory | Hyperplasia of olfactory epithelium | Rat inhalation studies | Reuzel et al., 1990, 1994b | Benchmark Concentration | 0.06 mg/m3 | 0.0006 mg/m3 | 100 | 1 | High | Medium | Medium | Threshold | Chronic |
| 71 | Naphthalene | 91-20-3 | Nervous, Respiratory | Nasal effects: hyperplasia and metaplasia in respiratory and olfactory epithelium, respectively | Chronic mouse inhalation study | NTP, 1992a | Lowest Observable Adverse Effect Level | 9.3 mg/m3 | 0.003 mg/m3 | 3000 | 1 | Medium | Low/Medium | Medium | Threshold | Chronic |
| 72 | Nitrobenzene | 98-95-3 | Nervous, Respiratory | Bronchiolization of the alveoli and olfactory degeneration | Chronic mouse study | CIIT, 1993 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 0.26 mg/m3 | 0.009 mg/m3 | 30 | 1 | High | High | Medium | None | Chronic |
| 73 | 2-Nitropropane | 79-46-9 | Hepatic | Liver focal vacuolization and nodules | Rat chronic inhalation study | Griffin et al., 1980, 1981; Angus Chemical Co., 1985a, b | Lowest Observable Adverse Effect Level | 16.0 mg/m3 | 0.02 mg/m3 | 1000 | 1 | Low | Low | Low | Threshold | Chronic |
| 74 | Phosgene | 75-44-5 | Respiratory | Collagen staining indicative of fibrosis | Subchronic inhalation study in rats | Kodavanti et al., 1997 | Benchmark Dose based on the LED10 (Lowest Effective Dose) | 0.03 mg/m3 | 0.0003 mg/m3 | 100 | 1 | Medium | Medium | Medium | Benchmark | Chronic |
| 75 | Phosphine | 7803-51-2 | Other | Decreased body weight | Mouse subchronic inhalation study | Barbosa et al., 1994 | No Observable Adverse Effect Level | 0.25 mg/m3 | 0.0003 mg/m3 | 1000 | 1 | Medium | Low | Low | Threshold | Chronic |
| 76 | Phosphoric acid | 7664-38-2 | Respiratory | Bronchiolar fibrosis | 13-week rat inhalation study | Aranyi et al., 1988a | Benchmark Concentration | 3.4 mg/m3 | 0.01 mg/m3 | 300 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 77 | Propionaldehyde | 123-38-6 | Nervous, Respiratory | Atrophy of olfactory epithelium | Subchronic inhalation study in rats | Union Carbide, 1993 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 8.0 mg/m3 | 0.008 mg/m3 | 1000 | 1 | Low/Medium | Low | Low/Medium | Benchmark | Chronic |
| 78 | Propylene glycol monomethyl ether (PGME) | 107-98-2 | Nervous | Mild reversible sedation | Rat/rabbit subchronic inhalation study | Landry et al., 1983 | No Observable Adverse Effect Level | 658.0 mg/m3 | 2.0 mg/m3 | 300 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 79 | Propylene oxide | 75-56-9 | Respiratory | Nest-like infolds of the nasal respiratory epithelium | 2-year rat chronic inhalation study | Kuper et al., 1988 | Lowest Observable Adverse Effect Level | 2.9 mg/m3 | 0.03 mg/m3 | 100 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 80 | Styrene | 100-42-5 | Nervous | CNS effects | Occupational study | Mutti et al., 1984 | No Observable Adverse Effect Level | 34.0 mg/m3 | 1.0 mg/m3 | 30 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 81 | Tetrachloroethylene (Perchloroethylene) | 127-18-4 | Nervous, Ocular | (See Note) | None | None | None | None | 0.04 mg/m3 | None | None | Medium | Medium | Medium | None | Chronic |
| 82 | 1,1,1,2-Tetrafluoroethane | 811-97-2 | Reproductive | Leydig cell hyperplasia | Rat chronic inhalation study | Collins et al., 1995 | Benchmark Concentration | 8200.0 mg/m3 | 80.0 mg/m3 | 100 | 1 | High | Medium | Medium | Threshold | Chronic |
| 83 | Tetrahydrofuran | 109-99-9 | Hepatic, Nervous | Increased liver weight and centrilobular cytomegaly, CNS effects (narcosis) | Subchronic mouse study | NTP (1998) | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 246.0 mg/m3 | 2.0 mg/m3 | 100 | 1 | High | Medium/High | Medium/High | None | Chronic |
| 84 | Toluene | 108-88-3 | Nervous | Neurological effects in occupationally-exposed workers | Multiple human studies | Abbate et al., 1993, Boey et al., 1997, Cavalleri et al., 2000, Eller et al., 1999, Foo et al., 1990, Murata et al., 1993, Nakatsuka et al., 1992, Neubert et al., 2001, Vrca et al., 1995, Zavalic et al., 1998a | No Observable Adverse Effect Level | 46.0 mg/m3 | 5.0 mg/m3 | 10 | 1 | High | High | High | Threshold | Chronic |
| 85 | 2,4-/2,6-Toluene diisocyanate mixture (TDI) | 26471-62-5 | Respiratory | Chronic lung-function decline | Prospective occupational study | Diem et al., 1982 | No Observable Adverse Effect Level | 0.002 mg/m3 | 7e-05 mg/m3 | 30 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 86 | 1,1,1-Trichloroethane | 71-55-6 | Hepatic | Liver histopathologic changes | 2-Year inhalation rat study, 14-Week inhalation mouse study | Quast et al. (1988, 1984), McNutt et al. (1975) | No Observable Adverse Effect Level | 1553.0 mg/m3 | 5.0 mg/m3 | 100 | 1 | Low | Medium | Medium | None | Chronic |
| 87 | 1,1,1-Trichloroethane | 71-55-6 | Hepatic | Liver histopathologic changes | 2-Year inhalation rat study, 14-Week inhalation mouse study | Quast et al. (1988, 1984), McNutt et al. (1975) | No Observable Adverse Effect Level | 1553.0 mg/m3 | 5.0 mg/m3 | 100 | 1 | Low | Medium | Medium | None | Subchronic |
| 88 | 1,1,1-Trichloroethane | 71-55-6 | Nervous | Performance on neurobehavioral tests | Human subjects exposed for 3.5 hr | Mackay et al. (1987) | Lowest Observable Adverse Effect Level | 950.0 mg/m3 | 9.0 mg/m3 | 100 | 1 | Medium | Medium | Medium | None | None |
| 89 | 1,1,1-Trichloroethane | 71-55-6 | Nervous | Performance on neurobehavioral tests | Human subjects exposed for 3.5 hr | Mackay et al. (1987) | Lowest Observable Adverse Effect Level | 950.0 mg/m3 | 7.0 mg/m3 | 100 | 1 | Medium | Medium | Medium | None | None |
| 90 | 1,1,1-Trichloroethane | 71-55-6 | Nervous | Performance on neurobehavioral tests | Human subjects exposed for 3.5 hr | Mackay et al. (1987) | Lowest Observable Adverse Effect Level | 950.0 mg/m3 | 7.0 mg/m3 | 100 | 1 | Medium | Medium | Medium | None | None |
| 91 | 1,1,1-Trichloroethane | 71-55-6 | Nervous | Performance on neurobehavioral tests | Human subjects exposed for 3.5 hr | Mackay et al. (1987) | Lowest Observable Adverse Effect Level | 950.0 mg/m3 | 6.0 mg/m3 | 100 | 1 | Medium | Medium | Medium | None | None |
| 92 | 1,1,1-Trichloroethane | 71-55-6 | Nervous | Performance on neurobehavioral tests | Human subjects exposed for 3.5 hr | Mackay et al. (1987) | Lowest Observable Adverse Effect Level | 526.0 mg/m3 | 5.0 mg/m3 | 100 | 1 | Medium | Medium | Medium | None | None |
| 93 | Trichloroethylene | 79-01-6 | Developmental, Immune | (See Note) | None | None | None | None | 0.002 mg/m3 | None | None | High | High | High | None | Chronic |
| 94 | 1,2,3-Trichloropropane | 96-18-4 | Respiratory | peribronchial lymphoid hyperplasia in male rats | 13-week inhalation Study | Johannsen et al., 1988 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 0.9 mg/m3 | 0.0003 mg/m3 | 3000 | 1 | Low/Medium | Low | Low | Benchmark | Chronic |
| 95 | Triethylamine | 121-44-8 | Respiratory | Inflammation of the nasal passage | 28-week rat inhalation study | Lynch et al., 1990 | No Observable Adverse Effect Level | 19.5 mg/m3 | 0.007 mg/m3 | 3000 | 1 | Medium | Low | Low | Threshold | Chronic |
| 96 | 1,2,4-Trimethylbenzene | 95-63-6 | Respiratory | Inflammatory lung lesions | Korsak et al. | 2000a | No Observable Adverse Effect Level | 61.65 mg/m3 | 0.2 mg/m3 | 300 | 1 | None | None | Low/Medium | None | Chronic |
| 97 | 1,2,4-Trimethylbenzene | 95-63-6 | Developmental | Decreased fetal weight | Saillenfait et al. | 2005 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 395.16 mg/m3 | 4.0 mg/m3 | 100 | 1 | None | None | Low/Medium | Benchmark | Chronic |
| 98 | 1,2,4-Trimethylbenzene | 95-63-6 | Other | Decreased maternal weight | Saillenfait et al. | 2005 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 758.06 mg/m3 | 3.0 mg/m3 | 300 | 1 | None | None | Low/Medium | None | Chronic |
| 99 | 1,2,4-Trimethylbenzene | 95-63-6 | Nervous | Decreased pain sensitivity in male Wistar rats | Korsak and Rydzyński | 1996 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 18.15 mg/m3 | 0.2 mg/m3 | 100 | 1 | None | None | Low/Medium | Benchmark | Subchronic |
| 100 | 1,2,4-Trimethylbenzene | 95-63-6 | Nervous | Decreased pain sensitivity in male Wistar rats | Korsak and Rydzyński | 1996 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 18.15 mg/m3 | 0.06 mg/m3 | 300 | 1 | Low/Medium | Low/Medium | Low/Medium | Benchmark | Chronic |
| 101 | 1,2,3-Trimethylbenzene | 526-73-8 | Respiratory | Inflammatory lung lesions | Korsak et al. | 2000b | No Observable Adverse Effect Level | 66.56 mg/m3 | 0.2 mg/m3 | 300 | 1 | None | None | Low/Medium | None | Chronic |
| 102 | 1,2,4-Trimethylbenzene | 95-63-6 | Hematologic | Decreased clotting time | Korsak and Rydzyński | 1996 | No Observable Adverse Effect Level | 24.3 mg/m3 | 0.08 mg/m3 | 300 | 1 | None | None | Low/Medium | None | Chronic |
| 103 | 1,2,3-Trimethylbenzene | 526-73-8 | Nervous | Decreased pain sensitivity in male Wistar rats | Korsak and Rydzyński | 1996 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 18.15 mg/m3 | 0.2 mg/m3 | 100 | 1 | None | None | Low/Medium | Benchmark | Subchronic |
| 104 | 1,2,3-Trimethylbenzene | 526-73-8 | Nervous | Decreased pain sensitivity in male Wistar rats | Korsak and Rydzyński | 1996 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 18.15 mg/m3 | 0.06 mg/m3 | 300 | 1 | Low/Medium | Low/Medium | Low/Medium | Benchmark | Chronic |
| 105 | 1,3,5-Trimethylbenzene | 108-67-8 | Developmental | Decreased fetal weight | Saillenfait et al. | 2005 | No Observable Adverse Effect Level | 367.75 mg/m3 | 4.0 mg/m3 | 100 | 1 | Low/Medium | Low/Medium | Low/Medium | None | Chronic |
| 106 | 1,3,5-Trimethylbenzene | 108-67-8 | Other | Decreased maternal weight | Saillenfait et al. | 2005 | No Observable Adverse Effect Level | 124.25 mg/m3 | 0.4 mg/m3 | 300 | 1 | None | None | Low/Medium | None | Chronic |
| 107 | 1,3,5-Trimethylbenzene | 108-67-8 | Nervous | Decreased pain sensitivity in male Wistar rats | Korsak and Rydzyński | 1996 | Benchmark Dose based on the LED10 (Lowest Effective Dose) | 18.15 mg/m3 | 0.2 mg/m3 | 100 | 1 | Low/Medium | Low/Medium | Low/Medium | Threshold | Subchronic |
| 108 | 1,3,5-Trimethylbenzene | 108-67-8 | Nervous | Decreased pain sensitivity in male Wistar rats | Korsak and Rydzyński | 1996 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 18.15 mg/m3 | 0.06 mg/m3 | 300 | 1 | Low/Medium | Low/Medium | Low/Medium | Threshold | Chronic |
| 109 | 1,2,3-Trimethylbenzene | 526-73-8 | Hematologic | Decreased segmented neutrophils | Korsak et al. | 2000b | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 16.65 mg/m3 | 0.06 mg/m3 | 300 | 1 | None | None | Low/Medium | Benchmark | Chronic |
| 110 | Vinyl acetate | 108-05-4 | Nervous, Respiratory | Nasal epithelial lesions | Chronic inhalation study in rats and mice | Owen, 1988 Beems, 1988 Dreef-van der Meulen, 1988 | No Observable Adverse Effect Level | 5.0 mg/m3 | 0.2 mg/m3 | 30 | 1 | High | High | High | Threshold | Chronic |
| 111 | Vinyl bromide | 593-60-2 | Hepatic | Hypertrophy, basophilic and eosinophilic foci, in the liver | Chronic rat inhalation study | Benya et al., 1982; Busey, 1979 | Lowest Observable Adverse Effect Level | 7.7 mg/m3 | 0.003 mg/m3 | 3000 | 1 | Medium | Low | Low | Threshold | Chronic |
| 112 | Vinyl chloride | 75-01-4 | Hepatic | Liver cell polymorphism | Rat chronic feeding study | Til et al., 1983, 1991 | No Observable Adverse Effect Level | 2.5 mg/m3 | 0.1 mg/m3 | 30 | 1 | High | Medium/High | Medium | Threshold | Chronic |
| 113 | Xylenes | 1330-20-7 | Nervous | Impaired motor coordination (decreased rotarod performance) | Subchronic inhalation study in male rats | Korsak et. al., 1994 | No Observable Adverse Effect Level | 39.0 mg/m3 | 0.1 mg/m3 | 300 | 1 | Medium | Medium | Medium | Threshold | Chronic |
| 114 | tert-Butyl Alcohol (tBA) | 75-65-0 | Urinary | Increased severity of nephropathy | Route-to-route extrapolation from 2-year drinking water study | NTP 1995 | Benchmark Concentration based on the LEC10 (Lowest Effective Concentration) | 491.0 mg/m3 | 5.0 mg/m3 | 100 | 1 | High | Medium | Medium | None | Chronic |
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