Effect of different boiling temperatures on heavy metal concentration of food crops sold in AWKA markets, Anambra state, Nigeria

Abstract

The presence of heavy metals in food crops poses significant public health risks due to their toxicity, bio-accumulation, and potential adverse health effects. This study investigates how boiling temperature treatments (50 and 100 °C) affect concentrations of heavy metals; lead (Pb), cadmium (Cd), arsenic (As), chromium (Cr), and mercury (Hg) in selected crops sold in Awka markets, Anambra State, Nigeria. Samples of 54 commonly consumed food crops known for metal uptake were analyzed using Atomic Absorption Spectrophotometry. Awka, a rapidly urbanizing city, faces potential contamination from traffic emissions, poor waste disposal, and possible use of polluted irrigation systems. Results reveal significant variations in heavy metal concentrations across crop types, species, and processing conditions. Chromium exhibited the highest concentrations in local rice (0.67 mg/kg), while arsenic and mercury were undetected in some samples. Millet (finger) and Oloka beans showed elevated lead and cadmium levels, respectively. Temperature treatments reduced arsenic and chromium levels but had limited effects on lead and cadmium. Although most heavy metal concentrations were within permissible limits, the persistence of certain metals in specific crops highlights potential health risks. These findings underscore the need for routine heavy metal surveillance, continuous monitoring of heavy metals in food crops and policies to mitigate contamination risks in food crops consumed in Awka and similar regions.