Analysis of nutrient loads, heavy metals and physicochemical properties of wastewater, wetland grass, and papaya samples: Gondar Malt factory, Ethiopia with global implication.

Robust attention was brought to researchers due to deterioration of wastewater quality of lakes and reservoirs as major global concerns by industrial release. The uncontrolled releases of effluents impose serious impacts for both aquatic and terrestrial environments. In the current study, many parameters like nutrient loads, heavy metals and physicochemical properties of wastewater, wetland grass, and papaya samples were analysed. The investigated nutrients, alkalinity, and total hardness in fresh water samples were within the allowable limits except for phosphate in fresh wastewater and alkalinity in wastewater. The detected levels of heavy metals (mg/L) in wastewater samples were:- Cd (0.386-0.905), Cr (ND-0.074), Cu (0.064-0.096), Mn (0.184-1.528), Fe (0.167-4.636), Zn (0.175-0.333), and Pb (0.044-0.892) (mg/L). The studied metals in the wastewater sample, except Cd, Fe, and Pb were lower than the allowable limit. The level of heavy metals in the grass and papaya samples ranged from Cd (37.14-147.62), Cr (ND-8.82), Cu (3.14-8.33), Mn (2.89-85.46), Fe(5.0-65.15), Zn (3.44-36.84), and Pb (ND-60.36) (mg/kg). The detected metals were below the permissible limits, except Cd, Cr, and Pb. The findings of the physicochemical characteristics in wastewater samples were computed: pH (6.61-8.54), temperatures (21.63-26.57 °C), TDS (205.9-1896 mg/L), EC (359.9-3226.67 µs/cm), BOD (12.0-732.67 mg/L), COD (3.67-1691.33 mg/L). Except for temperature and pH, all levels in the wastewater were above the recommended limit for wastewater discharge by USEPA.

Determination of proximate composition, selected essential and heavy metals in sesame seeds (Sesamum indicum L.) from the Ethiopian markets and assessment of the associated health risks.

In this study, the proximate composition, levels of essential and heavy metals; and health risk assessment were evaluated in sesame seed (Sesamum indicum L.) samples purchased randomly from local markets of three study sites in Ethiopia. A 0.15 g of dried and homogenized samples were digested using 6 mL of HNO3 (69-72%) and 3 mL of HClO4 (70%) at 120 °C for 3 h. The levels of proximate composition and essential metals in the sesame samples were determined by the Association of Official Agricultural Chemists (AOAC) and Flame Atomic Absorption Spectrometer (FAAS), respectively. The moisture content, crude fiber, ash content, fat, crude proteins and carbohydrate of sesame samples ranged between 3.15% and 5.52%, 4.21-4.40%, 3.10-4.75%, 55.75-56.9%, 22.65-23.39% and 8.34-8.80%, respectively. The accuracy of the procedure was validated by percent recovery of samples for all metals varied from 85.60% to 102.00%. The mean levels of the metals (mg/kg) were found in the range of 37.20-70.10 (Na), 315.1-338.00 (K), 209.00-216.50 (Mg), 328.00-341.30 (Ca), 12.60-12.90 (Fe), 4.90-5.00 (Cu) and 8.30-8.70 (Zn) mg/kg. The THQ values of heavy metals were found < 1, indicating that the consumption of sesame may not cause health risks to local consumers. The values of HI ranged from 1.5 × 10-3 to 1.8 × 10-3 in the study areas and may not have a possible adverse health effect on the adult population from the consumption of sesame seeds.

Levels and health risk assessment of trace metals in honey from different districts of Bench Sheko Zone, Southwest Ethiopia.

This study aimed to determine the levels and potential health risks posed by trace metals (Zn, Cu, Mn, Cd, Cr, and Pb) obtained in honey samples. The honey samples were from Sheko, Guraferda, Mizan Aman Town, Debub Bench, and Semien Bench in Bench Sheko Zone, Southern Ethiopia, and levels of trace metals were determined using atomic absorption spectroscopy (AAS). The levels of trace metals in honey samples across the provinces ranged as follows; Zn (1.78-4.02 mg/kg), Cu(1.85-2.35 mg/kg), Mn (0.75-1.25 mg/kg), Cd (0.011-0.038 mg/kg), Cr (0.25-0.55 mg/kg), respectively. The level of Pb was not detected in all honey samples. The levels of trace metals obtained were lower than the maximum permissible limit set by WHO/FAO. Limit of detection (LOD) and quantification (LOQ) were ranged from 0.00045 to 0.005 and 0.0015 to 0.016, for the tested metals, respectively. The estimated recoveries of the method were ranged from 92.66% to 103.00% showed a good agreement of accuracy. The EDI values (mg/kg) of the investigated trace metals in all honey samples were less than the maximum tolerable daily intake (MTDI). The values of the target hazard quotient (THQ) and the hazard index (HI) were less than unity. The target cancer risk (TCR) values of Cd in all honey samples showed the lowest carcinogenic risks with values ranged from 3.34E-07 to 1.27E-06. However, the TCR value of Cr in all honey samples ranged from 1.03E-05 to 2.43E-05 and was in the moderate range. The ∑ T C R value of Cd and Cr ranged from 1.15E-05 to 2.37E-05 and 1.23E-05 to 2.55E-05 for male and female adults, respectively, and were found in the moderate range. Therefore, there was no serious non-carcinogenic and carcenogenic risks to human health from exposure to trace metals through the consumption of this honey.

Analysis and health risk assessments of some trace metals in Ethiopian rice (white and red) and imported rice.

In this study, the levels of some trace metals (Cr, Cu, Mn, Pb, and Zn) in Ethiopian and imported rice samples were analysed. The rice samples were digested with a mixture of HNO3:HClO4:H2O2 (3:2:1 v/v) at a temperature of 200 °C for 2:30 h. The mean concentrations (mg/kg) of metals in Ethiopian and imported rice samples were found in the range of 4.82-17.04 for Cr, 11.30-18.30 for Cu, 6.04-9.22 for Mn; and 17.15-27.37 for Zn, within FAO/WHO limits. However, Pb was not detected in both rice samples. The Red rice contained higher levels of metals compared with the White rice. The Ethiopian rice recorded higher levels of metals than the imported ones. The estimated daily intake (mg/kg-day) was found to be at a safe level with reference to the maximum tolerable daily intake. Except for Cr, the values of the target hazard quotient (THQ) were also within the safe level in all the samples, posing no potential health risks on consuming rice. The hazard index values (HI) for the metals in Ethiopian rice except Jimma Red were slightly higher than unity, indicating the alert threshold level and potential health risks to rice consumers. Thus, the concentrations of these metals were less than the maximum limits set by FAO/WHO limits and most of THQ and HI values less than unity. Therefore, there was no serious noncarcinogenic risk to human health from exposure to metals through the consumption of these rice.