Summary
Melon seeds (Citrullus lanatus), locally known as agushi in Ghana, were collected from six market locations across the Bono, Bono East, and Ahafo regions of Ghana. Mean metal concentrations were analyzed using flame atomic absorption spectrometry (Cd, Pb) and hydride generation AAS (As, Hg). All detected mean concentrations were substantially below EU 2023/915 maximum levels for oilseeds (Cd 0.50 mg/kg, lead (Pb) 0.10 mg/kg, mercury (Hg) 0.05 mg/kg). Noncarcinogenic hazard indices (HI: 0.0091 to 0.0202) were well below 1.0, confirming negligible noncarcinogenic risk under the USEPA IRIS 2025 updated reference dose for arsenic. Incremental lifetime cancer risk (ILCR) values fell within the acceptable range of 10^-6 to 10^-4.
Key numbers
| Measure | Value | Units | Matrix | Source location |
|---|---|---|---|---|
| Mean cadmium (Cd) range (across markets) | 0.0017 to 0.0086 | mg/kg | Melon seeds | Abstract, p. 1 |
| Mean arsenic (As) range | 0.0013 to 0.0027 | mg/kg | Melon seeds | Abstract, p. 1 |
| Mean lead (Pb) range | 0.00103 to 0.00108 | mg/kg | Melon seeds | Abstract, p. 1 |
| Mean mercury (Hg) range | 0.000130 to 0.000383 | mg/kg | Melon seeds | Abstract, p. 1 |
| EU ML, cadmium (Cd) (oilseeds) | 0.50 | mg/kg | Reference | p. 2 |
| EU ML, lead (Pb) (oilseeds) | 0.10 | mg/kg | Reference | p. 2 |
| EU ML, mercury (Hg) (oilseeds) | 0.05 | mg/kg | Reference | p. 2 |
| Hazard index (HI) range | 0.0091 to 0.0202 | dimensionless | Adult males and females | Abstract |
| ILCR range | 1.04 × 10^-6 to 2.81 × 10^-6 | dimensionless | All population subgroups | Abstract |
Arsenic reference dose applied: USEPA IRIS 2025 updated RfD of 6.0 × 10^-5 mg/kg/day. No oral RfD was applied for lead per USEPA IRIS and EFSA guidance (no threshold-based RfD). Three population subgroups assessed: adult males (70 kg), adult females (60 kg), and children aged 6 to 12 years (26 kg).
Methods (brief)
Six market locations sampled. Approximately 50 g of melon seeds purchased from 10 independent vendors per location and composited into one pooled composite sample per location; three analytical replicates prepared from each composite. Wet digestion with concentrated HNO3/HClO4 (4:1 v/v) on a programmable hot plate. LOD: 0.0001 mg/kg cadmium (Cd), 0.0002 mg/kg arsenic (As), 0.0001 mg/kg (Pb), 0.00005 mg/kg (Hg). CRM: NIST SRM 1515 Apple Leaves. Standard daily intake: 25 g/day (adults), 10 g/day (children, scaled by body weight ratio).
Evidence fitness
Demonstrates that melon seeds from the Bono Region Ghanaian markets contain metal levels well below EU regulatory thresholds and pose negligible estimated dietary risk under current consumption patterns. The composite sampling strategy (one composite per market) means within-market variability is not captured. The finding is relevant to oilseed dietary exposure assessment in West Africa but cannot be extrapolated to other commodity classes or processing stages.
Limitations
Six markets is a reasonable but not comprehensive sample of the Ghanaian market. Compositing suppresses variability. All metrics are point estimates without uncertainty analysis.
Related evidence
- Dietary heavy-metal exposure
- Oilseeds
- Cadmium
- metals/total-arsenic
Update history
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