Summary
This study quantified cadmium, cobalt, lead, and total mercury in 71 seafood samples from four commercially important Ecuadorian species: shrimp (Protrachypene precipua), shrimp-prawn (Litopenaeus vannamei), blue marlin (Makaira nigricans), and Pacific thread herring (Opisthonema sp.), purchased from retail markets in Quito and Manta. Blue marlin had markedly elevated total mercury concentrations (mean 1117.7 µg/kg) consistent with biomagnification processes typical of apex predators. Shrimp-prawns showed the highest cadmium levels (mean 67.5 µg/kg). Lead and cobalt concentrations were below the limits of quantification in all samples. All detectable cadmium and total mercury concentrations remained below Codex Alimentarius and EU regulatory limits. Total mercury hazard quotient (HQ) for blue marlin exceeded 1.0 across all demographic groups under both mean and maximum consumption scenarios, while cadmium HQ remained below 1.0.
Key numbers
| Measure | Value | Units | Matrix | Source location |
|---|---|---|---|---|
| Mean THg, blue marlin | 1117.7 | µg/kg wet weight | Blue marlin muscle | Abstract |
| Mean cadmium (Cd), shrimp-prawn | 67.5 | µg/kg wet weight | Shrimp-prawn | Abstract |
| lead (Pb) concentration | below LOQ | — | All species | Abstract |
| Co concentration | below LOQ | — | All species | Abstract |
| THg HQ, blue marlin | greater than 1 | dimensionless | All age groups | Abstract |
| cadmium (Cd) HQ | below 1 | dimensionless | All age groups | Abstract |
| Adult body weight (19+ years) | 67.9 | kg | Ecuador population | p. 4 |
| Adult IR | 0.140 | kg per day | Ecuador Photographic Atlas | p. 4 |
| Toddler BW (less than 5 years) | 12.2 | kg | Ecuador ENSANUT | p. 4 |
| Child BW (6 to 12 years) | 27.8 | kg | Ecuador ENSANUT | p. 4 |
Methods (brief)
71 samples collected from retail markets in Quito and Manta between 2024 and 2026: 24 headless shrimps, 20 headless shrimp-prawns, 16 blue marlin muscle samples, 11 PTH samples. All samples freeze-dried. cadmium (Cd) and lead (Pb) by graphite furnace AAS. Total mercury by cold-vapor AFS (CVAFS). CRMs: DORM-5 and SPIN-1 (NRC Canada) for Cd, Pb, and mercury (Hg). Precision evaluated by duplicate digestions. Left-censored data handling: Cd (25% below LOQ) and Hg (18% below LOQ) set to half LOQ; Pb and Co: all below LOQ, no data handling (not used in EDI). Ecuadorian anthropometric and consumption data from ENSANUT.
Evidence fitness
This study is notable for identifying blue marlin as a mercury biomagnifier posing excess risk (HQ greater than 1) for Ecuadorian consumers, including children, under typical consumption scenarios. The mercury finding for blue marlin is consistent with global data on apex pelagic predators and reinforces species-specific consumption advisories. The cadmium finding in shrimp-prawn (67.5 µg/kg) is below EU MLs but documents the species-specific accumulation pattern of cadmium in demersal and filter-feeding crustaceans.
Limitations
Small sample sizes per species (11 to 24 samples). Sampling across a multi-year window (2024 to 2026) means samples are not from a single cohort or season. Lead and cobalt could not be detected in any sample, limiting analysis to mercury and cadmium.
Related evidence
- Dietary heavy-metal exposure
- Shrimp
- Fish
- metals/total-mercury
- Cadmium
Update history
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