Dichlorodifluoromethane (CASRN 75-71-8)
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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 First 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 |
*A comprehensive review of toxicological studies was completed 01/10/05 - please see section I.A.6 for more information.
_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 Rat Chronic Oral Sherman, 1974 |
NOAEL: 300 ppm LOAEL: 3000 ppm |
100
|
1
|
2E-1
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 Studies/Comments (Oral RfD)
None.
__I.A.5. Confidence in the Oral RfD
Study — High
Database — 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 database 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
A comprehensive review of toxicological studies published through 2004 was conducted. No new health effects data were identified that would be directly useful in the revision of the existing RfD for Dichlorodifluoromethane and a change in the RfD is not warranted at this time. For more information, IRIS users may contact the IRIS Hotline at hotline.iris@epa.gov or (202)566-1676.
__I.A.7. EPA Contacts (Oral RfD)
Please contact the IRIS Hotline for all questions concerning this assessment or IRIS, in general, at (202)566-1676 (phone), (202)566-1749 (FAX) or hotline.iris@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.
_III.
[reserved]
_IV. [reserved]
_V. [reserved]
_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., V. | Drinking Water Health Advisories, EPA Regulatory Actions, and Supplementary Data were removed from IRIS on or before April 1997. IRIS users were directed to the appropriate EPA Program Offices for this information. |
12/03/2002 | I.A.6. | Screening-Level Literature Review Findings message has been added. |
03/03/2005 | I.A.6. | Screening-Level Literature Review Findings message has been removed and replaced by comprehensive literature review conclusions. |
_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