Environmental Systems Research

Table 1 The toxicity responses (dose response) to heavy metals as the oral reference dose (RfD) (USEPA IRIS 2011; Wongsasuluk et al. 2014)

From: Pollution evaluation, sources and risk assessment of heavy metals in hand-dug wells from Ejisu-Juaben Municipality, Ghana

Heavy metals	Oral RfD (mg/kg/day)
Cd	5.0 × 10⁻⁴
Cu	4.0 × 10⁻²
Pb	3.5 × 10⁻³
Zn	0.3
Fe	0.7
Mn	0.014

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