Reksten et al. 2021 — Heavy metals in 24 fish species from the Bay of Bengal
This study measured tAs, Cd, tHg, and Pb in 1,111 individual fish spanning 24 commercially important species collected from the Bay of Bengal coast in Sri Lanka and Bangladesh. With the largest individual-level sample size yet reported for Bay of Bengal fish metal contamination, it provides robust species-level distributions and a complete health risk assessment including target hazard quotients (THQ), hazard index (HI), and carcinogenic risk estimates. The most notable finding is cadmium: 58% of sampled small fish (body length ≤25 cm) exceeded the EU maximum limit of 0.050 mg/kg for Cd in fish muscle, driven by species that are consumed whole rather than filleted.
Key numbers
Mean concentrations across all 24 species (wet weight, ICP-MS):
- tAs: 1.9 mg/kg w.w. (range not reported as a single overall range; species-level means varied widely)
- Cd: 0.19 mg/kg w.w. mean; 58% of small fish (≤25 cm body length) exceeded EU max of 0.050 mg/kg
- tHg: 0.06 mg/kg w.w.
- Pb: 0.01 mg/kg w.w.
EU maximum limits (for context):
- Cd in fish muscle: 0.050 mg/kg w.w. (small species may be lower; 0.10 mg/kg for larger fatty fish)
- tHg in most fish: 0.500 mg/kg w.w.
- Pb in fish muscle: 0.300 mg/kg w.w.
Sample structure: n=1,111 individual fish from 24 species; fish collected from local markets and landing sites in Sri Lanka (southern coastal region) and Bangladesh (Cox’s Bazar district); analysis by ICP-MS, wet weight basis.
Health risk assessment: THQ values for the general adult population were <1 for Pb and tHg; Cd THQ elevated for frequent consumers of small species. Carcinogenic risk from tAs was estimated using total arsenic, which overestimates iAs-specific risk since marine fish arsenic is largely organic arsenobetaine; authors acknowledge this limitation.
Methods (brief)
ICP-MS analysis; wet weight basis for all metals. Fish purchased from coastal markets and landing sites in 2018–2019. Muscle tissue (edible portion) analyzed for most species; for small whole-consumed species, analysis included viscera, which elevates Cd readings compared to muscle-only sampling. No arsenic speciation reported; tAs values include organic arsenobetaine. LOQ values species-specific; detection rates high for Cd (Cd above LOQ in most samples from small species).
Implications
Certification: Cadmium exceedance in small whole-consumed fish from Bay of Bengal is a significant finding for product categories using dried small fish, fish meal, or fish powder as ingredients. Any product incorporating whole dried anchovies, sardines, or similar small pelagic species from South/Southeast Asian fisheries warrants Cd-specific testing.
Courses: Strong case study for explaining why fish-size and consumption-format (fillet vs whole) create dramatically different Cd exposure profiles. The 58% exceedance rate for small species against EU limits is concrete and memorable.
App: tAs values not suitable for iAs risk scoring without speciation. Cd values are meaningful for product risk scoring when species and consumption format are known; whole-consumed small species carry materially higher Cd than filleted large species.
Microbiome: Not applicable.