Table 2.

Interpretation of the potential ecological risk index (PERI).

Classification	Value	New calculated values for 9 elements
low risk	RI < 150	RI < 80
moderate risk	150 RI < 300	80 RI < 160
considerable risk	300 RI < 600	160 RI < 320
high risk	>= RI 600	>= RI 320