Overview
Adjei-Mensah and colleagues bought cassava, cocoyam, plantain and yam from farms beside rivers used for illegal small-scale mining at Akwatia (diamonds) and Obuasi (gold), Ghana, on five occasions between March and June 2019, and from prepared-food sellers in the two towns. Farm samples were washed and peeled, then split into unprocessed, boiled, fried and roasted portions in the laboratory. Lead, cadmium, arsenic and mercury were measured by ICP-MS after microwave digestion (manganese by flame AAS). Table 4 reports plantain results by town and processing method as means ± SD in mg/kg; the basis (fresh or dry) is not stated, and samples were milled without a described drying step.
Key numbers
- Unprocessed peeled plantain pulp: lead 1.02 ± 0.65 mg/kg (Obuasi) and 1.11 ± 0.65 mg/kg (Akwatia); total mercury 0.12 ± 0.07 and 0.13 ± 0.05 mg/kg; total arsenic 0.02 ± 0.01 mg/kg at both towns; cadmium <0.01 mg/kg (Table 4).
- Laboratory boiling and frying gave plantain lead of 0.04–0.07 mg/kg; roasting gave 0.13 ± 0.06 mg/kg (Obuasi) and 0.75 ± 0.04 mg/kg (Akwatia) (Table 4; percentage reductions in Table 6).
- Mercury fell to 0.04–0.05 mg/kg after boiling or frying of Akwatia plantain but changed little at Obuasi (0.10–0.11 mg/kg) or after roasting (0.11–0.12 mg/kg) (Table 4).
- Prepared plantain bought from market sellers is reported only pooled with other crops (Figures 1–2), not as plantain results.
Methods (brief)
Microwave digestion (HNO3/H2O2) and ICP-MS (Agilent 7700) for lead (Pb), cadmium (Cd), arsenic (As) and mercury (Hg); spike recoveries 89.6–99.8%; no certified reference material reported. The printed detection limit (“0.0000 ppb” for Cd) is not usable, and “<0.01” is not defined as an LOD or LOQ. Per-group sample counts are not stated; Table 1 gives 40 plantain samples overall.
Evidence Fitness
The paired design supports within-study comparisons of processing methods for the same farm samples. Changes are concentration changes on an unstated basis without moisture or mass balance, so they do not show how much metal was removed. The abstract calls boiling the most effective method while Section 3.6 ranks frying first; Akwatia roasted lead (0.75 ± 0.04) carries the same significance letter as Obuasi roasted (0.13 ± 0.06). The intake and hazard tables (Tables 7–8) contain values that do not follow from Table 4. Values were checked against the publisher PDF (HMI-GAP-INGEST-1 batch-01).