Table 2. Health based guidance value by Joint FAO/WHO Expert Committee on Food Additives

Heavy metals	Health based guidance value	Health based guidance value(PTWI)
Cd	PTMI 25 µg/kg b.w./month	5.83 µg/kg b.w./week
Cu	PMTDI 0.5 mg/kg b.w./day	3,500 µg/kg b.w./week
Zn	PMTDI 0.3–1 mg/kg b.w./day	2,100–7,000 µg/kg b.w./week
Hg	PTWI 4 µg/kg b.w./week	4 µg/kg b.w./week
As	PTWI 15 µg/kg b.w./week	PTWI 15 µg/kg b.w./week

Cd, cadmium; Cu, copper; Zn, zinc; Hg, mercury; As, arsenic; PTMI, provisional tolerable monthly intake; PMTDI, provisional maximum tolerable daily intake; PTWI, provisional tolerance weekly intake.