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Table 2 Heavy metal concentrations in P. annectens from Nyabarongo river in comparison with other global studies

From: Physicochemical quality of water and health risks associated with consumption of African lung fish (Protopterus annectens) from Nyabarongo and Nyabugogo rivers, Rwanda

Study areaMean heavy metal concentration (mg/kg)YearAuthors
FeMnCuZnCrCdPb
Nyabarongo river, Rwandaa272.8 ± 0.36 (336.0 ± 0.70)292.2 ± 0.25 (302.6 ± 1.22)8.8 ± 0.36 (6.4 ± 0.26)135.2 ± 0.15 (44.7 ± 0.20)148.0 ± 0.21 (138.2 ± 0.17)BDL (BDL)432. 0 ± 0.50 (302.4 ± 1.50)2020This study
Lower River Benue, Nigeria0.36 ± 0.02NDNDNDNDND0.09 ± 0.012018[15]
Oguta Lake, NigeriaNDND30.10ND3.750.4118.102016[16]
Nkisa river, Nigeria174.6611.814.92211.331.030.790.982014[17]
Benin city, Nigeria.NDNDNDNDND0.32F, 0.52DND2011[18]
Anambra river, Nigeria60.23 ± 0.37b0.94 ± 0.063.01 ± 0.4010.60 ± 0.080.16 ± 0.03ND0.01 ± 0.022009[19]
54.60 ± 0.20c1.00 ± 0.012.86 ± 0.3111.40 ± 0.300.17 ± 0.02ND0.01 ± 0.02
FAO/WHO limit30.01.030.040.010.00.50.5 [20]
  1. Detection limits calculated with reagent blanks were 1.50, 0.20, 0.60, 2.50, 0.50, 1.14, 1.20 and 0.37 mg/kg for Fe, Mn, Cu, Zn, Cr, Cd and Pb, respectively. Values in italics are higher than their corresponding heavy metal permissible limits in fish
  2. ND not determined, F fresh sample, D dry sample, BDL below method detection limit
  3. aResults in parentheses are for P. annectens from Kirinda bridge; b, c results in these rows were obtained in wet and dry seasons respectively