DETERMINATION OF HEAVY METALS IN SELECTED LOCAL FRUITS

Abstract

This study investigated the concentrations of five trace elements—iron (Fe), copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd)—in five commonly consumed fruits (watermelon, pineapple, banana, orange, and pawpaw) sold in major markets and roadside vendor points within Sokoto Metropolis, Nigeria. The aim was to determine whether the levels of these metals fall within internationally accepted safety limits and to provide baseline data on the quality of fruits available to consumers in the region. Fruit samples were collected, prepared, and analyzed using wet acid digestion followed by Flame Atomic Absorption Spectroscopy (FAAS) on a Shimadzu AA6300. All analyses were carried out in triplicate with strict quality control measures, including method blanks, calibration checks, and precision verification. Results showed that essential metals (Fe, Cu, Zn) were present in all fruits at levels within safe and nutritionally acceptable limits. Pineapple recorded the highest iron concentration (29.83 mg/kg), while orange contained the highest copper (1.25 mg/kg) and zinc (2.05 mg/kg). However, all fruits exhibited lead (0.37–0.62 mg/kg) and cadmium (0.13–0.43 mg/kg) concentrations exceeding the WHO/FAO Codex Alimentarius permissible limits (Pb: 0.1 mg/kg; Cd: 0.05 mg/kg). Watermelon showed the highest cadmium concentration, whereas pawpaw recorded the highest lead levels, indicating possible environmental contamination from soil, irrigation water, agrochemicals, or atmospheric deposition from traffic. The findings highlight a significant public health concern, particularly regarding chronic exposure to toxic metals such as Pb and Cd. The results underscore the need for regular monitoring of fruits, improved agricultural practices, stricter enforcement of food safety regulations, and public awareness on safe consumption habits. This study provides essential baseline data and contributes valuable insight into heavy metal contamination patterns in fruits consumed within Sokoto State.