Proximate analysis, levels of trace heavy metals and associated human health risk assessments of Ethiopian white sugars

In this study, white sugar samples collected from five Ethiopian sugar manufacturing plants were analyzed for their proximate composition, and trace heavy metals level (Fe, Co, Ni, Mn, Zn, Cr, Cd, and Pb). Human health risk assessments associated with heavy metals exposure from white sugar ingestion were also assessed. Proximate analysis was conducted according to AOAC methods. For heavy metals determination, the sugar samples were digested using a mixture of HNO3, HClO4 and H2O2 (4:3:1) at 250 °C for 3 h prior to FAAS analysis. The measured mean values (%) of proximate parameters including moisture, ash, fiber, protein, fat and carbohydrate were found in the range of 0.07–0.61, 2.56–4.33, 0.06–0.24, 0.78–1.49, 1.16–1.89 and 92.13–95.03, respectively. The average concentration of heavy metals found in the sugar samples were ranged as 1.366–12.502, 0.107–0.268, 0.099–0.842, 0.458–1.000, 10.140–25.480, 0.053–0.322, 0.427–0.827 and 0.074–0.528 in mg/kg for Fe, Mn, Ni, Co, Zn, Cr, Cd and Pb, respectively. All the studied metals are below FAO/WHO permissible limit except Cd and Pb in Kessem, Fincha'a and Metahara samples. The target hazard quotient (THQ) and hazard index (HI) values are <1, indicating no non-carcinogenic risks of the heavy metals to an adult population via consumption of white sugar. However, the single element incremental lifetime cancer risk (ILCR) occurrence is probable from Ni for samples obtained from Kessem sugar factory (ILCR>1.0 × 10−4). The cumulative ILCR of heavy metals (Ni, Cr, Cd and Pb) resulting from consumption of white sugar by an adult person reveal a potential adverse cancer risk (ILCR>1.0 × 10−4) for all the studied samples except for sugar samples obtained from Wonji sugar factory. Therefore, continuous monitoring of these toxic metals should be made mainly by sugar industries and responsible government regulatory bodies to avert heavy metal toxicity associated with white sugar consumption in Ethiopia.