Horizontal and Vertical Distribution of Heavy Metals in Farm Produce and Livestock around Lead-Contaminated Goldmine in Dareta and Abare, Zamfara State, Northern Nigeria

Table 3

Oral reference doses (RfD), highest estimated daily intake, and upper tolerable daily intakes (UL) for investigated metals.

S/N	Element	RfD (mg/kg/day) [13]	Highest estimated daily intake (mg/day)	UL (mg/day) [references]
1	Pb	0.004	0.1626	0.4 [14]; 0.5 [15, 16]
2	Cd	0.001	0.0031	1.0 [14]
3	Zn	0.300	0.0929	40 [17, 18]
4	Cr	1.5	0.0354	0.5 [19]
5	Cu	0.040	0.0412	10 [17, 18]
6	Mg	—	0.3884	350 [20, 21]
7	Ni	0.020	0.0315	7 (children 1–3 years); 40 (adults 19–70 years) [22]