Table 2 Showing limits of selected heavy metals in drinking water, waste water, soils and vegetables as recommended by WHO, Kenya, China, USA EPA, World Bank, and India (CPCB).

From: Levels of heavy metals in wastewater and soil samples from open drainage channels in Nairobi, Kenya: community health implication

Organization /Country The variable whose standards were reviewed Recommended limits for the studied heavy metals (ppm)
Hg Cd Pb Cr (hexavalent) Tl Ni
WHO Drinking water57 0.006 0.005 0.01 0.1 NG 0.07
Waste water (effluents)16,20 0.0019 0.003 0.01 0.05 NG 0.02
Soils (for agriculture)15 –0.0810 0.003 0.1 0.1 NG 0.05
Plants (Vegetables)58 0.1 0.02 0.1–0.3 1.3 NG 10
China (Chinese Ministry of Health; and The National Standards) Drinking water26 0.0001 0.005 0.01 0.05 0.0001 0.03
Waste water (effluents)59 0.005 0.03 1.0 0.5 NG 1.0
Soils (for agriculture)60,61 0.3–1.0 0.3–0.6 80 150–300 NG 40–60
Plants (vegetables)62,63,64,65 0.01 0.05–0.2 0.1–0.3 0.5–1.0 NG 1.0
Kenya (NEMA and KEBS) Drinking Water66,67 0.02 0.01 0.05 NG NG NG
Waste water (effluents)66 0.005 0.01 0.01 0.05 NG 0.3
Public sewers66 0.05 0.5 1.0 0.05 NG 3.0
Soils (for agriculture) NG NG NG NG NG NG
Plants (Vegetables)68 0.01 0.05 0.3 NG NG NG
US EPA Drinking Water69,70 0.002 0.005 0.05 0.1 (total Cr) 0.013 0.02
aSWQS limit level71 0.00272 0.009 8.5 0.08 6.3 8.3
Water reclaimed from effluent for irrigation73 NG 0.01 5.0 0.1 NG 0.2
Waste water (effluents)74 0.00003 0.01 0.006 0.05 NG 0.2
Soils (for a garden)75 1.0 0.48 200 11 NG 72
Plants (Vegetables)76 0.015 0.2 0.377 2.377 NG NG
World Bank Waste water (effluents)78 0.01 0.1 0.1 0.5 (total Cr) NG 0.510
India CPCB Inland surface water79 0.01 2.0 0.1 0.1 NG 3.0
Public sewers79 0.01 1.0 1.0 2.0 NG 3.0
  1. aSWQS stands for Surface Water Quality Standards; The references for the recommended limits (ppm) are shown in superscript; ppm implies mg/kg or mg/L; NG stands for Not Given.