contamination levels in 120 food samples collected from three distinct vending

Overview

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Key numbers

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• 38% of samples exceeded the Codex Alimentarius TVC threshold of 5 log₁₀
• cfu/g. E. coli was present in 25% of samples, with the highest incidence in
• fresh salads (45%), while Salmonella spp. appeared in 8%, predominantly in
• meat and salad items. S. aureus was detected in 30% of samples, especially in
• fried snacks and grilled meats. Pb levels exceeded permissible limits in 15% of
• urban dwellers up to 80% in some cities depend on street foods as a primary nutritional
• HACCP guided investigation of street vended salads, 98% of vendors skipped pre washing
• season from November to March, with mean annual temperatures ranging between 25 °C
• of 35%, with 95% confidence and 5% margin of error. This yielded a total of 120 food
• overall Total Viable Count (TVC) ranged from 3.1 to 7.2 log₁₀ cfu/g, with 38% of samples
• • E. coli was detected in 25% of samples, with the highest prevalence in fresh salads
• • Salmonella spp. was present in 8% of samples, exclusively in meat based and salad
• • Staphylococcus aureus was detected in 30% of samples, especially in fried snacks and
• • Bacillus cereus was found in 12% of samples, mainly in rice based dishes.
• Table 1. Microbiological quality of street vended foods in Benin City, Nigeria.
• Fresh salads 6.1 ± 0.7 3.9 ± 0.7 45% 10% 30% 10%
• categories. Lead (Pb) exceeded WHO/Codex permissible limits (0.1 mg/kg for most
• foods) in 15% of samples, particularly in grilled meat and salads sourced from roadside
• vendors. Cadmium (Cd) levels were generally below permissible limits, except in 3% of
• Table 2. Chemical contaminants in street vended foods in Benin City, Nigeria.
• Fresh salads 0.12 ± 0.03 20% 0.01 ± 0.004 0% ND 40%
• Figure 3. Mean Lead (Pb) Concentration Across Food Category
• al., 2017; Afolabi et al., 2018). The highest E. coli prevalence in fresh salads (45%) aligns
• limits in 15% of samples particularly grilled meats and roadside salads supporting earlier
• 3. Infrastructure improvements – Provide access to potable water, waste disposal

Methods (brief)

• contamination levels in 120 food samples collected from three distinct vending
• pesticide residues using Atomic Absorption Spectrophotometry (AAS) and
• Gas Chromatography–Mass Spectrometry (GC–MS). Results revealed that
• 38% of samples exceeded the Codex Alimentarius TVC threshold of 5 log₁₀
• cfu/g. E. coli was present in 25% of samples, with the highest incidence in
• meat and salad items. S. aureus was detected in 30% of samples, especially in
• samples, particularly grilled meats and roadside salads; however, Cd and
• 2025). Additionally, while isolation of pathogens from samples is common, fewer studies
• derived contaminants) in the same food samples.
• consumed crops using AAS and GC MS, underscoring the importance of validated
• preliminary mapping of the study sites. The sample size was determined using prevalence
• samples from 40 vendors (approximately 13–14 samples per location). Vendors included
• Food samples (200–250 g for solids; 200–250 mL for liquids) were collected
• aseptically using sterile gloves, forceps, and containers. Each sample was placed in sterile,
• type, food category, and date/time of collection. Samples were stored in insulated cool
• 1. Heavy metals (Pb, Cd, Hg, Cr) – Samples digested using nitric–perchloric acid and
• analyzed by Atomic Absorption Spectrophotometry (AAS); results compared to
• Chromatography–Mass Spectrometry (GC–MS) using external standards.

Implications

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Wiki pages this source may touch

• Fish — marine, non-predatory (sardines, anchovies, salmon, cod)
• teething-and-snacks
• Mercury
• Cadmium
• Lead
• Aluminum
• Chromium

Verification notes

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Update history

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