Non-cancer risks and mitigation strategies of fe, mn, cu and cr in milled maize flour

Abstract

In Uganda, maize (Zea mays), is milled into flour that is used as an ingredient in many food products including baby foods. Milling is mainly done in hammer mills that are fabricated using mild steel. Mild steel is made up of iron (Fe), manganese (Mn), copper (Cu) and chromium (Cr) as the major heavy metals (HM). During milling, hammer mill parts wear out and release metal particles into the flour. Heavy metals are a risk factor for chronic illnesses such as cancer, diabetes and heart disease. The safety of maize flour with regard to HM contamination arising from milling operations in Uganda is not known. This study aimed assessed the non-cancer risk and mitigation strategies to minimize Fe, Cu, Cr and Mn exposure in maize flour. A total of fifty samples (25 maize grain and 25 maize flour) were obtained from 5 milling enterprises in Kampala city. Metal concentration was determined using Atomic Absorption Spectrophotometry (AAS). Non-cancer risks due to HM exposure were determined using the non-cancer hazard quotient (HQ) and hazard index (HI) described by the United States Environmental Protection Agency (US EPA). Multi-Criteria Decision Analysis (MCDA) using Promethee-Gaia software 1.4 Academic Edition was used to determine the best risk management option. Data was analyzed with A General Linear model using SPSS for Windows, Version 16.0 (2007), SPSS Inc, Chicago, IL, USA. Milled flour samples had significantly (p < 0.05) higher concentrations of HM than the grain. Heavy metal concentration ranged from 0.257 to 1.782, 0.016 to 0.198, 0.122 to 0.501 and not detected (ND) to 1.151 mg/kg for Fe, Cu, Cr and Mn, respectively. The HQ and HI values were less than the United States Environment Protection Agency (US EPA) management level of 1 for both children and adults. Consumers of maize flour produced in hammer mills in Kampala will not experience adverse health effects. Nevertheless, the bioaccumulation of HM in the body organs poses a danger. Therefore, the possible development of risk should be monitored on a regular basis with the view of putting in place measures to protect public health.