Table 5: Risk assessment outcome manifestations due to inconsistent toxicity factor rounding.
Soil chemical |
Hypothetical exposure point concentration (mg/kg) |
Incidental soil ingestion hazards (HQs) for a hypothetical site resident1 |
||||
Mathematical RfDo |
HQ |
|
‘Rounded Up’ RSL Table RfDo |
HQ |
||
endrin
|
25 |
2.50E-04 |
1.20 |
3.00E-04 |
1.00 |
|
hexabromodiphenyl ether |
17 |
1.50E-04 |
1.36 |
2.00E-04 |
0.93 |
|
octabromodiphenyl ether |
250 |
2.51E-03 |
1.20 |
3.00E-03 |
1.00 |
|
|
||||||
Soil chemical |
Hypothetical exposure point concentration (mg/kg) |
Mathematical RfDo |
HQ |
|
‘Rounded Down’ RSL Table RfDo |
HQ |
chloroform |
1000 |
1.29E-02 |
0.93 |
1.00E-02 |
1.21
|
|
furan |
100 |
1.40E-03 |
0.86
|
1.00E-03 |
1.20 |
|
trichlorobenzene, 1,2,4- |
1000 |
1.48E-02 |
0.81 |
1.00E-02 |
1.20 |
1Computed HQs do not follow straightly from the toxicity information of the 2019 RSL Table. That RSL Table bears numerous erroneous risk-based concentrations (rbc), as in those for the incidental soil ingestion uptake route of residents and industrial workers. The erroneous values reflect standard exposure factors (e.g., adult body weight; exposure duration [in years]) adopted several years ago (USEPA 2014), not having been implemented in the rbc calculations.