Overview
This study quantified heavy metal concentrations (As, Cd, Co, Cu, Cr, Fe, Mn, Ni, Pb, Zn) in water, sediment, muscle, gut, and bone of two fish species — Oreochromis niloticus (Nile tilapia) and the endemic and endangered Coptodon kottae — from Lake Barombi Kotto, a crater lake in Cameroon. Metal concentrations in lake water were generally low and below permissible standards; sediment concentrations ranged from 0.86 ± 0.03 mg/kg for Cd to 560.1 ± 11.15 mg/kg for Fe. In fish, the organ distribution followed bones > gut > muscle for most metals, with bioconcentration factors ranging from 1.6 (Fe) to 1,568 (Mn). Consumption of both fish species contributes less than 1.0% of the permissible tolerable daily/weekly intake (PTDI/PTWI) for most metals, but Pb has the potential to exceed permissible exposure levels under high-consumption scenarios for adults.
Key numbers
- Sediment Cd range: 0.86 ± 0.03 mg/kg (dry weight)
- Sediment Fe: 560.1 ± 11.15 mg/kg (dry weight)
- Bioconcentration factors: 1.6 (Fe) to 1,568 (Mn) in fish tissues
- Organ Cd distribution: bones > gut > muscle for both species
- All metals contributed < 1.0% of PTDI/PTWI from fish consumption at typical rates
- Pb has potential to exceed permissible levels at high-consumption scenarios (adults)
- n = 10 samples per species (20 fish total); 6 water and sediment sampling sites
- Metals not detected above LOD at routine fish consumption levels for most analytes
Methods (brief)
Fish muscle, gut, and bone dissected and analyzed separately. Wet digestion in aqua regia; metal analysis by ICP-MS or ICP-OES (method not specified for all metals). Water samples by standard methods. Total metals reported (no speciation). Health risk assessment: PTDI/PTWI approach per WHO/FAO guidelines.
Implications
Certification: Demonstrates Pb as the analyte of greatest dietary concern from freshwater lake fish even in non-industrialized African settings; organ distribution data supports bone/whole-fish products as higher-risk than muscle-only. Courses: Lacustrine fish as an understudied contamination pathway; Mn bioconcentration data notable. App: Freshwater tilapia contamination data point for sub-Saharan Africa.
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Update history
The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.
| Commit | Date | Change | Description |
|---|---|---|---|
| e317189 | 2026-08-11 | correction | 6 sections added; narrative text revised |