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Table 7 Non-carcinogenic health risk assessment summary for the selected metals in the water for adults and children via ingestion and dermal routes

From: Concentrations, hydrochemistry and risk evaluation of selected heavy metals along the Jimi River and its tributaries at Obuasi a mining enclave in Ghana

 

RfDing (µg/kg/day)

RfDderm (µg/kg/day)

Adults

Children

HQing

HQderm

HQing

HQderm

As

0.3

 

0.00 to 3.42 × 10−2

–

0.00 to 1.30 × 10−1

–

Cd

0.5

0.025

0.00 to 1.81 × 10−3

0.00 to 1.72 × 10−4

0 to 6.90 × 10−3

0 to 5.06 × 10−4

Fe

700

140

2.06 × 10−4 to 5.64 × 10−3

4.88 × 10−6 to 1.34 × 1004

7.86 × 10−4 to 2.15 × 10−2

1.44 × 10−5 to 3.95 × 10−4

Ni

20

5.4

1.51 × 10−5 to 1.24 × 10−2

1.06 × 10−6 to 8.67 × 10−4

5.75 × 10−5 to 4.71 × 10−2

3.13 × 10−6 to 2.56 × 10−3

Zn

300

120

3.42 × 10−3 to 8.84 × 10−3

2.43 × 10−6 to 6.29 × 10−6

1.30 × 10−4 to 3.38 × 10−4

7.17 × 10−6 to 1.86 × 10−5

Pb

1.4

0.42

0 to 6.24 × 10−3

0.00 to 3.95 × 10−4

0 to 2.38 × 10−2

0 to 1.16 × 10−3

HIing/derm

–

–

3.64 × 10−3 to 6.03 × 10−2

8.37 × 10−6 to 1.57 × 10−3

9.74 × 10−4 to 2.30 × 10−1

2.47 × 10−6 to 4.64 × 10−3

  1. The chronic daily intake (CDI) for As, Cd, Fe, Ni, Zn and Pb for both adult and children were observed to be less than 1 (Table 8). Therefore, CDI indices for heavy metals were found in the order: Fe > Zn > As > Pb > Cd > Ni. The CR value was calculated for only As, Cd and Pb because the value of cancer slop for the other could not be assessed in the Integrated Risk Information System (IRIS, provided by USEPA database; USEPA 2005). The CR value for As, Cd and Pb for both adult and children (Table 8) were generally found to exceed the safe limit of cancer risk. Generally a CR value greater than 1 in a million (10−6) is considered significant by USEPA.