Toxic and Essential Metals in Staple Foods Commonly Consumed by Students in Ekiti State, South West, Nigeria

Overview

Iyabo and colleagues measured zinc, copper, cadmium, and lead in staple foods commonly consumed by university students in Ekiti State, southwest Nigeria. The foods were grouped as cereal/cereal products, legume products, and tuber products, with concentrations reported in mg/kg. The paper reports no arsenic, mercury, chromium, or nickel data.

Key numbers

Table 1 reports heavy metal concentrations in food items in mg/kg:

Detection limits printed below Table 1:

Table 2 reports average levels in mg/kg by food group:

Additional source-reported values:

• The text states overall Table 1 ranges as Zn 0.43-39.5, Cu 0.82-17.6, cadmium (Cd) LTDL-0.50, and lead (Pb) LDTL-0.30 mg/kg.
• Highest individual-item levels were Zn 39.5 mg/kg in wheat, Cu 17.6 mg/kg in groundnut, and Cd 0.50 mg/kg in rice with beans & fish.
• The paper states lead was significantly high in yam, Amala (yam and cassava flour), Garri (fried cassava), and potato; Table 1 lists several of those foods at Pb 0.30 mg/kg.
• Recommended permissible limits printed by the source were Zn 99.0 mg/kg, Cu 40.0 mg/kg, Pb 0.30 mg/kg, and Cd 0.20 mg/kg as set by FAO/WHO (2001).
• Percentage recoveries were Zn 92.2%, Cu 94.3%, Cd 96.0%, and Pb 98.2%.

Methods (brief)

A questionnaire was administered to 200 volunteered Ekiti State University students to identify commonly consumed staple foods. The identified foods were purchased from food vendors in the research locations, categorized into cereals, legumes, and tubers, air-dried for about 2-3 days, oven-dried at 105 °C for 24 h, and pulverized. One gram of each solid staple food was digested by dry ashing. Zinc, copper, lead, and cadmium were measured by atomic absorption spectrophotometer (AAS, Perkin Elmer Model 2130), and data were compared with FAO/WHO food-standard guideline values.

Implications

This source contributes Nigeria-market occurrence evidence for Zn, Cu, Cd, and Pb in prepared staple-food forms, including rice-containing mixed meals, wheat/noodle products, legume meals, peanut/groundnut, and tuber-based foods. The values are reported as food-item concentrations in mg/kg; the paper does not give a wet/dry basis beyond the stated sample drying protocol, so downstream normalization should preserve this uncertainty. Several entries are mixed meals rather than single ingredients and should be routed by product form rather than silently assigned to one ingredient.

Related evidence

• Rice
• Wheat
• Noodles
• Beans
• Peanuts
• Root vegetables
• Potatoes
• Yam
• Melon
• Mixed Meals, Rice-Containing
• Mixed Meals, Non-Rice
• Pasta (wheat-based)
• Other grain products (oat, millet, quinoa, barley)
• Legumes and Pulses, Other
• Peanuts
• Root and Tuber Vegetables
• Zinc
• Copper
• Cadmium
• Lead

Update history

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