Level Of Toxic Metals In Consumable Aquatic Plant Ledermanniella Schlechteri From Congo River And Potential Risk Assessment Through Plant Consumption

Abstract

The accumulation of toxic metals in food consumption has been identified as a serious human health risk. Ledermanniella schlechteri (LDMSC) is a genus of Podostemaceae plant family and is well known to grow naturally on rocks of rapid waters. LDMSC is rich in nutrients and one of the most consumed aquatic vegetables in Africa. However, there are not any studies performed to assess the level of toxic metals in this aquatic plant. Consequently, the aim of this study is to assess the concentration of toxic metals in LDMSC and to evaluate the potential health risk to the consumers. Plant samples were collected in Congo River at the rapid of Kinsuka-Mimosa, in the vicinity of Kinshasa, Capital City of the Democratic Republic of the Congo (DRC). Toxic metal (Cr, Cu, Zn, As, Cd and Pb) concentrations in LDMSC were determined using Inductively Coupled Plasma Mass Spectrometry whereas Hg analysis was performed using atomic absorption spectrophotometry. Metal levels in LDMSC were compared with international regulation for human consumption set by the Food and Agriculture Organization (FAO) and World Health Organization (WHO). Metal concentrations in LDMSC varied significantly according to sampling sites. The average values (in mg kg-1) ranging from 0.44 -9.1 (Cr), 0.14-4.52 (Ni), 5.5-78.4 (Cu), 336.14-1520.91 (Zn), 0.08-0.49 (As), 0.21-0.78 (Cd), 0.44-11.81 (Pb), and 0.02-0.24 (Hg). In all sampling sites, the average concentration of Zn, As, Cd, and Hg in plant samples exceeded the FAO/WHO permissible limits for human consumption. According to FAO/WHO regulation and the calculated values of targeted risk quotient, the impact on human health is likely to occur. On other hand, according to the metal levels in LDMSC, this plant can be used as bioindicator to evaluate the state of river pollution by toxic metals.