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Heavy metals and microbial contamination of palm oil produced and sold at some markets in Kogi East Area, Kogi State, Nigeria

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Overview

Enemuor and colleagues measured physicochemical quality, microbial contamination, and selected heavy metals in traditionally processed palm oil sold in three Kogi East markets in Nigeria. The routeable HMI evidence is Table 3, which reports market-level mean concentrations in ppm for cadmium, chromium, lead, arsenic, copper, and iron. Cadmium was highest in Idah market samples, while arsenic and iron were highest in Anyigba and Idah samples respectively.

Key numbers

  • Sample set: 30 palm oil samples, with ten samples purchased from ten local sellers in each of Ankpa, Anyigba, and Idah markets.
  • Product scope: crude/traditionally processed palm oil sold commercially in Kogi East, Nigeria.
  • cadmium (Cd) in palm oil, Table 3: 0.001 ppm in Anyigba, 0.010 ppm in Ankpa, and 0.460 ppm in Idah; the source lists a WHO limit of 0.050 ppm.
  • chromium (Cr) in palm oil, Table 3: less than 0.001 ppm in Ankpa and Anyigba, and 0.040 ppm in Idah; the source lists a WHO limit of 0.100 ppm.
  • lead (Pb) in palm oil, Table 3: less than 0.001 ppm in all three market groups; the source lists a WHO limit of 0.010 ppm.
  • As in palm oil, Table 3: 0.040 ppm in Ankpa, 0.290 ppm in Anyigba, and 0.190 ppm in Idah; the source lists a WHO limit of 0.010 ppm. The source reports arsenic as arsenic (As), not inorganic arsenic.
  • Cu in palm oil, Table 3: less than 0.001 ppm in Ankpa, 0.006 ppm in Anyigba, and 0.030 ppm in Idah; the source lists a WHO limit of 1.300 ppm.
  • Fe in palm oil, Table 3: 1.880 ppm in Ankpa, 4.660 ppm in Anyigba, and 7.340 ppm in Idah; the source lists a WHO limit of 1.000 ppm.

Methods (brief)

The study collected palm oil samples in sterile universal bottles from three main local markets in Kogi East and transported them to the laboratory for microbiological and heavy-metal analysis. For metals, each 5 g oil sample was digested with 20 ml of an acid mixture (650 ml concentrated HNO3, 80 ml perchloric acid, and 20 ml concentrated H2SO4), and metals were quantified by flame atomic absorption spectrometry. The methods section names lead, cadmium, iron, arsenic, and copper as the analytes, but Table 3 also reports chromium concentrations without describing a separate Cr workup.

Implications

Certification: This is direct occurrence evidence for palm oil as an edible oil and broader context for the cooking-oils-other product row. The values are market-level means in source-reported ppm, so they should be admitted as summary evidence unless sample-level values are recovered.

Courses: The paper is useful for teaching how traditional processing, open-market distribution, and local handling can create market-specific contamination signals in cooking oils.

App: Palm oil can carry a Nigeria/Kogi-specific occurrence flag for Cd, total arsenic, Cr, Pb non-detects, Cu, and Fe. The data should not be generalized globally without market stratification.

Microbiome: No direct microbiome endpoint.

Update history

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