Table 3.

Guidelines for the maximum permissible limit (MPL) values of selected heavy metals in sewage sludge used as agricultural fertilizer.

Heavy metal	US EPAa mg/kg	CCMEb mg/kg	EECc mg/kg	Franced mg/kg	Average∗ value mg/kg
Pb	840	600	750–1200	800	804
Cd	85	22	20–40	20	39.25
As	75	40–75	-	-	66.25
Hg	17	24	16–25	10	17.88

^aUnited States Environmental Protection Agency [23]. ^bCanadian Council of Ministers of the Environment [24]. ^cEuropean Economic Community/European Union [25]. ^dData for France [25]. ^∗Where a range is reported, the average value was calculated from the midpoint.