Table 4.

Guidelines for the maximum permissible limit (MPL) values of selected heavy metals in agricultural soil.

Metal	FAO/WHOa mg/kg	ECbmg/kg	UScmg/kg	Franced mg/kg	Germanyd mg/kg	Austriad mg/kg	SEPA China (Grade III) mg/kg	Arab-German Coop Projectfmg/kg	Average∗ mg/kg
Pb	90–400	50–300	50–300	70–150	100	100	500	100	166.25
Cd		1–3	1.6	1–3	1.5–3	5	1	1	2.12
As	-	20	14	30	50	50	-	-	32.8
Hg	1	1	0.5	1	2	5	1.5	-	1.71

^aFood and Agriculture Organization of the United Nations and the World Health Organization [26]. ^bEuropean Council/Union [27]. ^cUnited States [28]. ^dData for France, Germany and Austria [29]. ^eState Environmental Protection Administration of China [30]. ^fArab-German Cooperation project 1997–2003 [31]. ^∗Where a range is reported, the average value was calculated from the midpoint.