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Dichlorodifluoromethane. US EPA IRIS.
http://www.epa.gov/iris/subst/0040.htm
United States Environmental Protection Agency
IRIS - Integrated Risk Information System
I.A. REFERENCE DOSE FOR CHRONIC ORAL EXPOSURE (RfD)
I.B. REFERENCE CONCENTRATION FOR CHRONIC
0040 Dichlorodifluoromethane; CASRN 75-71-8 Health assessment information on a chemical substance is included in IRIS only after a comprehensive review of chronic toxicity data by U.S. EPA health scientists from several Program Offices and the Office of Research and Development. The summaries presented in Sections I and II represent a consensus reached in the review process. Background information and explanations of the methods used to derive the values given in IRIS are provided in the Background Documents. STATUS OF DATA FOR Dichlorodifluoromethane File On-Line 01/31/1987 Category (section) Status Last Revised ----------------------------------------- -------- ------------ Oral RfD Assessment (I.A.) on-line 11/01/1995 Inhalation RfC Assessment (I.B.) no data Carcinogenicity Assessment (II.) no data
_I. CHRONIC HEALTH HAZARD ASSESSMENTS FOR NONCARCINOGENIC EFFECTS __I.A. REFERENCE DOSE FOR CHRONIC ORAL EXPOSURE (RfD) Substance Name -- Dichlorodifluoromethane CASRN -- 75-71-8 Last Revised -- 11/01/1995 The oral Reference Dose (RfD) is based on the assumption that thresholds exist for certain toxic effects such as cellular necrosis. It is expressed in units of mg/kg-day. In general, the RfD is an estimate (with uncertainty spanning perhaps an order of magnitude) of a daily exposure to the human population (including sensitive subgroups) that is likely to be without an appreciable risk of deleterious effects during a lifetime. Please refer to the Background Document for an elaboration of these concepts. RfDs can also be derived for the noncarcinogenic health effects of substances that are also carcinogens. Therefore, it is essential to refer to other sources of information concerning the carcinogenicity of this substance. If the U.S. EPA has evaluated this substance for potential human carcinogenicity, a summary of that evaluation will be contained in Section II of this file. ___I.A.1. ORAL RfD SUMMARY Critical Effect Experimental Doses* UF MF RfD -------------------- ----------------------- ----- --- --------- Reduced body weight NOAEL: 300 ppm 100 1 2E-1 (converted to mg/kg/day Rat Chronic Oral 15 mg/kg/day) Study LOAEL: 3000 ppm Sherman, 1974 (converted to 150 mg/kg/day)
*Conversion Factors: 1 ppm = 0.05 mg/kg/day (assumed rat food consumption) ___I.A.2. PRINCIPAL AND SUPPORTING STUDIES (ORAL RfD) Sherman, H. 1974. Long-term feeding studies in rats and dogs with dichlorodifluoromethane (Freon 12 Food Freezant). Haskell Laboratory for Toxicology and Industrial Medicine Report No. 24-74. Haskell Laboratory (Sherman, 1974) conducted feeding studies in which dogs and rats received 300 ppm or 3000 ppm of dichlorodifluoromethane in the diet for 2 years. Additionally, carcinogenic and three-generation reproductive studies were conducted in rats. Clinical biochemical, urine analytical, hematological or histopathological evaluations were performed. Except for decreased weight gain in rats (about 20% in females) receiving 3000 ppm (150 mg/kg/day) dichlorodifluoromethane, no other adverse effects were attributed to this compound in either rats or dogs. This study is sufficiently complete to derive an RfD for adequate protection against adverse human health effects. The high dose (3000 ppm or 150 mg/kg/day) caused decreased body weights in rats and is therefore considered a LOAEL, whereas the low dose (300 ppm or 15 mg/kg/day) in rats produced no adverse effects attributable to the oral administration of dichlorodifluoromethane, and is the NOAEL. ___I.A.3. UNCERTAINTY AND MODIFYING FACTORS (ORAL RfD) UF -- The NOEL from the 2-year rat study (15 mg/kg/day) and an uncertainty factor of 100 (10 for species extrapolation and 10 for sensitive individuals) were used to derive the RfD of 0.2 mg/kg/day, or 10 mg/day for a 70-kg human being. MF -- None ___I.A.4. ADDITIONAL COMMENTS (ORAL RfD) None. ___I.A.5. CONFIDENCE IN THE ORAL RfD Study -- High Data Base -- Medium RfD -- Medium The Haskell Laboratory study is a chronic oral study in two species, which incorporated extensive clinical and toxicologic parameters. Therefore, a high level of confidence in the study is appropriate. Confidence in the data base is medium because of the lack of teratology and reproductive data. Medium confidence in the RfD follows. ___I.A.6. EPA DOCUMENTATION AND REVIEW OF THE ORAL RfD Source Document -- U.S. EPA, 1982 This document has undergone a limited Agency review. Other EPA Documentation -- None Agency Work Group Review -- 07/08/1985, 07/22/1985 Verification Date -- 07/22/1985 ___I.A.7. EPA CONTACTS (ORAL RfD) Please contact the IRIS Hotline for all questions concerning this assessment or IRIS, in general, at (301) 345-2870 (phone), (301) 345-2876 (FAX) or Hotline.IRIS@epamail.epa.gov (internet address).
__I.B. REFERENCE CONCENTRATION FOR CHRONIC INHALATION EXPOSURE (RfC) Substance Name -- Dichlorodifluoromethane CASRN -- 75-71-8 Not available at this time.
_II. CARCINOGENICITY ASSESSMENT FOR LIFETIME EXPOSURE Substance Name -- Dichlorodifluoromethane CASRN -- 75-71-8 This substance/agent has not undergone a complete evaluation and determination under US EPA's IRIS program for evidence of human carcinogenic potential.
_VI. BIBLIOGRAPHY Substance Name -- Dichlorodifluoromethane CASRN -- 75-71-8 Last Revised -- 08/01/1990 __VI.A. ORAL RfD REFERENCES Sherman, H. 1974. Long-term feeding studies in rats and dogs with dichlorodifluoromethane (Freon 12 Food Freezant). Haskell Laboratory for Toxicology and Industrial Medicine Report No. 24-74. U.S. EPA. 1982. Errata: Halomethanes Ambient Water Quality Criteria Docu- ment for the Protection of Human Health. Prepared by the Office of Health and Environmental Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH.
__VI.B. INHALATION RfC REFERENCES None
__VI.C. CARCINOGENICITY ASSESSMENT REFERENCES None
_VII. REVISION HISTORY Substance Name -- Dichlorodifluoromethane CASRN -- 75-71-8 -------- -------- -------------------------------------------------------- Date Section Description -------- -------- -------------------------------------------------------- 03/01/1988 I.A.1. Dose conversion clarified 03/01/1988 I.A.5. Confidence levels revised 08/01/1989 I.A.2. Citation clarified 08/01/1989 VI. Bibliography on-line 08/01/1990 I.A. Text edited 08/01/1990 III.A. Health Advisory on-line 08/01/1990 IV.F.1. EPA contact changed 08/01/1990 VI.D. Health Advisory references added 01/01/1992 I.A.7. Primary contact changed 01/01/1992 IV. Regulatory actions updated 11/01/1995 I.A.7. Contact changed 04/01/1997 III.,IV., Drinking Water Health Advisories, EPA Regulatory Actions, and V. Supplementary Data were removed from IRIS on or before April 1997. IRIS users were directed to the appropriate EPA Program Offices for this information.
VIII. SYNONYMS Substance Name -- Dichlorodifluoromethane CASRN -- 75-71-8 Last Revised -- 01/31/1987 75-71-8 ALGOFRENE TYPE 2 ARCTON 6 Dichlorodifluoromethane DIFLUORODICHLOROMETHANE DWUCHLORODWUFLUOROMETAN ELECTRO-CF 12 ESKIMON 12 F 12 FC 12 FLUOROCARBON-12 FREON 12 FREON F-12 FRIGEN 12 GENETRON 12 HALON ISCEON 122 ISOTRON 12 KAISER CHEMICALS 12 LEDON 12 PROPELLANT 12 R 12 RCRA WASTE NUMBER U075 REFRIGERANT 12 UCON 12 UCON 12/HALOCARBON 12 UN 1028
Last updated: 5 May 1998
URL: http://www.epa.gov/iris/subst/0040.htm