Heavy metals concentrations (mg/kg dry weigh)					Reference
Cd	Cu	Ni	Pb	Zn	Reference
<0.03	0.06	0.08	0.05	1.51	This study
0.06	-	12.23	0.32	7.62	[9]
0.16	0.19	0.42	2.21	4.26	[10]
0.0006	-	0.06	0.01	-	[11]
0.08	0.09	0.19	-	0.04	[12]
0.001	-	-	0.01	-	[13]
0.004	0.003	0.11	0.11	0.04	[15]
0.05	1.47	-	0.19	1.36	[16]
0.06	0.15	1.76	3.20	0.06	[34]
0.54	1.13	2.43	0.62	4.06	[35]
-	0.25	-	-	0.16	[36]
0.14	0.50	-	0.76	2.05	[37]