Quantification of Heavy Metals and Pesticide Residues in Widely Consumed Nigerian Food Crops Using Atomic Absorption Spectroscopy (AAS) and Gas Chromatography (GC).

Kingsley O Omeje,Juliet Ozioko,Giacomo Sardo,Benjamin O Ezema,Nnenna C Onyishi,Charles Odilichukwu R Okpala,Finbarr Okonkwo,Waheed A Rasaq

doi:10.3390/toxins13120870

Abstract

More still needs to be learned regards the relative contamination of heavy metals and pesticide residues, particularly those found in widely consumed Nigerian food crops like cereals, vegetables, and tubers. In this current study, the heavy metals and pesticide residues detectable in widely consumed Nigerian food crops were respectively quantified using atomic absorption spectroscopy (AAS) and gas chromatography (GC). Specifically, the widely consumed Nigerian food crops included cereals (rice, millet, and maize), legume (soybean), tubers (yam and cassava), as well as leaf (fluted pumpkin, Amaranthus leaf, waterleaf, and scent leaf) and fruit vegetables (okro, cucumber, carrot, and watermelon). Results showed that the detected heavy metals included arsenic (As), cadmium (Cd), chromium (Cr), cobalt (Co), iron (Fe), lead (Pb), manganese (Mn), mercury (Hg), and nickel (Ni), whereas the pesticide residues included Aldrin, Carbofuran, g-chlordane, Chlorpyrifos, DichloroBiphenyl, Dichlorodiphenyldichloroethane (DDD), Dichlorodiphenyltrichloroethane (DDT), Dichlorvos, Endosulfan, Heptachlor, Hexachlorobenzene (HCB), Isopropylamine, Lindane, t-nonachlor, and Profenofos. Across the studied food crops, the concentrations of heavy metals and pesticides were varied, with different trends as they largely fell below the established maximum permissible limits, and with some exceptions. Our findings suggest there could be a somewhat gradual decline in the concentration of the heavy metals and pesticide residues of these studied food crops when compared to previously published reports specific to Nigeria. To help substantiate this observation and supplement existing information, further investigations are required into the concentration of these heavy metals and pesticide residues specific to these studied food crops at other parts of the country.

Highlights

For the most part, fruits and vegetables provide essential phytochemicals and other nutrients to help reduce chronic ailments like obesity, diabetes, and cancers [1]
The maximum permissible limits established by reputable international regulators, specific to the detected heavy metals in this current work are summarized in Table 1 [30,31,32,33,34,35]
We demonstrated the comparative levels of heavy metals and pesticide residues in commonly consumed cultivated food crops in Nigeria, and the combined use of atomic absorption spectroscopy (AAS) and gas chromatography (GC) has helped to actualise this

Summary

Introduction

Fruits and vegetables provide essential phytochemicals and other nutrients to help reduce chronic ailments like obesity, diabetes, and cancers [1]. Cereals and tubers comprise nutrients, such as proteins, carbohydrates, minerals, and vitamins [2] and provide economic opportunity with a view to reducing rural poverty and unemployment [3]. All the above-mentioned cultivated food crops are largely susceptible to diverse pest attacks at the cultivated/farm field, which negatively influence both the economic and nutritional aspects of product quality. Controlling pest infestations requires the application of pesticides, which help to enhance farm productivity and quality [4,5,6]. Pesticides applied to agricultural crops must adhere to all applicable regulations, which ensure the remaining post-harvest chemical residues are within the consumer permissible/safe limits [6,9]

Methods

Results

Conclusion