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--- Assocunot*
EPA-450/
CANCER RISK FROM OUTDOOR EXPOSURE TO AIR TOXICS
U.S. Environmental Protection Agency Office of Air1 Quality Planning- and Standards Research Triangle Park,. North Carolina 27711
External Review Draft
September 1989
TABLE 2-6 (concluded)
UNIT RISK FACTORS USED TO COMPARE CANCER RISK
POLLUTANT
EPA CLASSIFICATION*
UNIT RISK FACTORS Uo/mSr1
REFERENCE
76. 1,1,2,2-Tetrachloroethane
77. Thiourea 78. Toxaphene
79. 1,1,2-Trichloroethane 80. Trichloroethylene 81. 2,4,6-Trichlorophenol 82. Vinyl chloride
83. Vinylidene chloride
C 82 B2 C
B2 B2 A C
5.8x10'*
5.5x10'* 3.2x10'* 1.6x10'*
1.7x10'* V 5.7x10'*
^ 4.1xl0'4
5.0x10'*
3 3 3 3 2 3 Zc 1
* For a discussion of how EPA evaluates suspect carcinogens and more information on these classifications, refer to "Guidelines for Carcinogen Risk Assessment" (51 Federal Register 33992). The EPA classifications used in this report,are:
A proven human carcinogen
B probable human carcinogen (B1 indicates limited evidence from human studies; 82 indicates sufficient evidence from animal studies but inadequate evidence from human studies)
C - possible human carcinogen
6 Based on Inhalation study. Oral study suggests a unit risk factor of 3.3xlO*3.
c Oral studies suggest a unit risk factor of 4.2xl0'5. U.S. Environmental Protection Agency, Office of Research and Development, Office of Health and Environmental Assessment. Health Effects Assessment Summary Tables First Quarter FY89. January 1989.
References
1. Integrated Risk Information System. 2. Office of Health and Environmental Assessment. 3. U.S. Environmental Protection Agency. Hazardous Waste TSOF -
Background Information for Proposed RCRA Air Emission Standards, Volume II - Appendices. Preliminary Oraft. March 1988. pp. E-8 through E-13, 4. Draft Supplemental Rule for Hazardous Waste Incinerators. Appendix B, Unit Risks for Carcinogenic Constituents. 5. IEMP-Philadelphia. Developed from EPA's Drinking Water Criteria Document. 3/2/84. 6. U.S. EPA, Office of Solid Waste. 7. Southeast Chicago Study.
2-21
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Acryl
SM&foxioi '#f5`6.9xl0"
r; BuylliEr**^ ~
3.3xl0`3 4.0x10"
3*3~$vr*tiej* Oarr^s
4.6xl0-7 2.3xl0'3
Chloroform
l.OxlO'5
j72 7'Z^jCT's Sztj-dere ciOraaiae
r.stic'" 5.1x10"
Ethylene oxide
3.6x10"
Formaldehyde
6. lxlO"4
Gasoline vapors
7.5xl0`7
Methyl chloride
1.4xl0'7
Methylene chloride
1.8xl0`7
Nickel (subsulfide)
3.3x10"
Perch!oroethylene
1.7x10"
Propylene oxide
1.2x10"
Styrene
2.9xl0`7
Trichloroethylene
4.1x10"
Vinyl chloride
2.6x10"
Vinylidene chloride
4.2xl0's
l.lxlO'3 8.3x10" 1.7xl0'3 2.4xl0'3
2.8x10" 1.8xl0'3 2.3xlO'5 :.2x:c" 2.*10" 1.0x10" 1.3xl0'5 6.6xl0'7
3.6x10" 4.7xl0`7 4.8x10" '5.8xl0`7
3.7x10"5.7xl0'7
1.7x10" 4.1x10" S.OxlO'5
X Change
+6400 +20 48 +500 +60770 -22 +130 44$
-72 +113 -12 +2,470 +161 +45 66 -97 +97 -59 *58
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