Residual (pounds) = (0.5^[Year 1/HL]) + (0.5^[Year 2/HL])
+ (0.5^[Year 3/HL]) + … (0.5^[Year 70/HL])
ln 2
−
×t
N
1 2
t = N 0 × e
t
106
Toxic Chemicals
This equation yields the same results as the following equation, used to calculate
how much of a chemical will remain after time t, or residual, based on frequency,
time, and quantity due to both new releases and residual up to the point just before
time t, based on the HL of a substance:
where N t is the quantity after time t, N 0 is the quantity due to both new releases and
residual up to the point just before time t, t ½ is the HL, and t is the time.
This resulted in a residual between 1 lb, with a relatively short HL, and 70 lb, a
relatively long HL, for the TRI chemicals over the course of a 70-yr period. Since
toxicity is based on annual exposure over a 70-yr life expectancy, this residual was
then divided by 70 yrs, resulting in the chemical-specific PFs varying between 1/70
and 70/70, or 1, as presented in Table 8.1. TRI chemicals for which HL values were
not available are not included in this table.
TABLE 8.1
Persistence Factors of TRI Chemicals
Chemical
Half-Lives (yrs)
Residual
(lb)
PF
Water
Soil
Sediment
Air
Average
1-(3-Chloroallyl)-3,5,7-triaza-1 0.49
0.99
4.38
0.00
1.47
3
0.04
azoniaadamantane chloride
1,1,1,2-Tetrachloro-20.16
0.33
1.48
9.04
2.75
4
0.06
fluoroethane
1,1,1,2-Tetrachloroethane
0.16
0.33
1.48
2.41
1.10
2
0.03
1,1,1-Trichloroethane
0.16
0.33
1.48
4.66
1.66
3
0.04
1,1,2,2-Tetrachloro-10.16
0.33
1.48
3.56
1.38
3
0.04
fluoroethane
1,1,2,2-Tetrachloroethane
0.16
0.33
1.48
0.17
0.54
1
0.02
1,1,2-Trichloroethane
0.10
0.21
0.93
0.23
0.37
1
0.02
1,1-Dichloro-1-fluoroethane
0.10
0.21
0.93
7.40
2.16
4
0.05
1,1-Dimethyl hydrazine
0.04
0.08
0.38
0.00
0.13
1
0.01
1,2,3-Trichloropropane
0.10
0.21
0.93
0.13
0.34
1
0.02
1,2,4-Trichlorobenzene
0.16
0.33
1.48
0.08
0.51
1
0.02
1,2,4-Trimethylbenzene
0.10
0.21
0.93
0.00
0.31
1
0.02
1,2-Butylene oxide
0.04
0.08
0.38
0.02
0.13
1
0.01
1,2-Dibromo-3-chloropropane
0.10
0.21
0.93
0.10
0.34
1
0.02
1,2-Dibromoethane
0.04
0.08
0.38
0.17
0.17
1
0.01
1,2-Dichloro-1,1,20.10
0.21
0.93
3.56
1.20
2
0.03
trifluoroethane
1,2-Dichloro-1,1-difluoroethane 0.10
0.21
0.93
2.74
1.00
2
0.03
+ (0.5^[Year 3/HL]) + … (0.5^[Year 70/HL])
ln 2
−
×t
N
1 2
t = N 0 × e
t
106
Toxic Chemicals
This equation yields the same results as the following equation, used to calculate
how much of a chemical will remain after time t, or residual, based on frequency,
time, and quantity due to both new releases and residual up to the point just before
time t, based on the HL of a substance:
where N t is the quantity after time t, N 0 is the quantity due to both new releases and
residual up to the point just before time t, t ½ is the HL, and t is the time.
This resulted in a residual between 1 lb, with a relatively short HL, and 70 lb, a
relatively long HL, for the TRI chemicals over the course of a 70-yr period. Since
toxicity is based on annual exposure over a 70-yr life expectancy, this residual was
then divided by 70 yrs, resulting in the chemical-specific PFs varying between 1/70
and 70/70, or 1, as presented in Table 8.1. TRI chemicals for which HL values were
not available are not included in this table.
TABLE 8.1
Persistence Factors of TRI Chemicals
Chemical
Half-Lives (yrs)
Residual
(lb)
PF
Water
Soil
Sediment
Air
Average
1-(3-Chloroallyl)-3,5,7-triaza-1 0.49
0.99
4.38
0.00
1.47
3
0.04
azoniaadamantane chloride
1,1,1,2-Tetrachloro-20.16
0.33
1.48
9.04
2.75
4
0.06
fluoroethane
1,1,1,2-Tetrachloroethane
0.16
0.33
1.48
2.41
1.10
2
0.03
1,1,1-Trichloroethane
0.16
0.33
1.48
4.66
1.66
3
0.04
1,1,2,2-Tetrachloro-10.16
0.33
1.48
3.56
1.38
3
0.04
fluoroethane
1,1,2,2-Tetrachloroethane
0.16
0.33
1.48
0.17
0.54
1
0.02
1,1,2-Trichloroethane
0.10
0.21
0.93
0.23
0.37
1
0.02
1,1-Dichloro-1-fluoroethane
0.10
0.21
0.93
7.40
2.16
4
0.05
1,1-Dimethyl hydrazine
0.04
0.08
0.38
0.00
0.13
1
0.01
1,2,3-Trichloropropane
0.10
0.21
0.93
0.13
0.34
1
0.02
1,2,4-Trichlorobenzene
0.16
0.33
1.48
0.08
0.51
1
0.02
1,2,4-Trimethylbenzene
0.10
0.21
0.93
0.00
0.31
1
0.02
1,2-Butylene oxide
0.04
0.08
0.38
0.02
0.13
1
0.01
1,2-Dibromo-3-chloropropane
0.10
0.21
0.93
0.10
0.34
1
0.02
1,2-Dibromoethane
0.04
0.08
0.38
0.17
0.17
1
0.01
1,2-Dichloro-1,1,20.10
0.21
0.93
3.56
1.20
2
0.03
trifluoroethane
1,2-Dichloro-1,1-difluoroethane 0.10
0.21
0.93
2.74
1.00
2
0.03