Heavy metal pollution and evaluation of health risk of amaranth around Don Bosco wastewater treatment plant, Iringa, Tanzania

Abstract

One of the world's most significant sources of environmental pollution is heavy metals contamination of soil, water, and agricultural products. Liver cancer, kidney damage, anaemia, coma, hypertension and sporadic fever are among the illnesses that might result from consuming plants contaminated with heavy metals. This study assesses heavy metals (Cu, Mn, Cd, Cr, Ni and Pb) contamination and associated human health risks in amaranth (Amaranthus hybridus) grown near Don Bosco wastewater treatment plant in Iringa municipal, Tanzania. The study measured the concentration of heavy metals in amaranth vegetables using AAS. The level of Mn in the vegetables ranged between 67.90 and 493.44 mg/kg. The mean concentration of Mn obtained was 280.67 mg/kg, lower than the permissible levels set by FAO/WHO but above the limit as set by TBS. The Cu levels in amaranth ranged between 6.37 and 7.90 mg/kg, with a mean concentration of 7.24 mg/kg lower than the permissible limits set by FAO/WHO and TBS. The Cd levels in amaranth ranged between 0.05 and 0.35 mg/kg, and the mean concentration was 0.20 mg/kg below the permissible limit set by FAO/WHO and TBS. The calculated daily intake consumption fell in the following sequence: Mn > Cu > Cd. The hazard quotient (HQ) for Mn and Cd is 261.66 and 6.45, respectively, higher than the allowed limit (HQ < 1), and the hazard index (HI) for all samples was HI > 1, which indicates the consumption of these veggies could pose a harm to one's health. Additionally, the assessment of cancer risks revealed that Mn and Cd levels exceeded the USEPA recommended threshold of 1E-04, indicating a risk of one additional cancer case for every 10,000 individuals consuming amaranth vegetables. Thus, regularly checking for heavy metal contamination in vegetables is critical to minimize health hazards.

Keywords: Amaranth vegetables; Dail intake of metals; Health risk assessment; Heavy metals; Mchicha; Wastewater.