Hussein et al. 2023 — Pb, Cd, Hg, As, Al in freshwater and marine fish, Egypt
This primary occurrence study measured five metals (Pb, Cd, Hg, As, Al) in the edible flesh of six fish species purchased from El-Obour market, Egypt, and calculated estimated daily intake (EDI) and hazard quotient (HQ) for Egyptian consumers. All six species exceeded European Commission maximum permissible limits (MPL) for Pb and Cd in a proportion of samples; 30% of Lates niloticus samples exceeded the MPL for Hg. Despite exceedances of individual species limits, hazard index (HI) values for combined metals were below 1, suggesting no non-carcinogenic health risk at current Egyptian fish consumption rates.
Key numbers
All values reported as mean ± SD in mg/kg wet weight (edible flesh), n=20 per species:
Lead (Pb):
- Oreochromis niloticus: 0.09 ± 0.02 mg/kg (10% above EU MPL)
- Mugil cephalus: 0.11 ± 0.03 mg/kg (15% above EU MPL)
- Lates niloticus: 0.31 ± 0.04 mg/kg (75% above EU MPL; highest)
- Epinephelus tauvina: 0.17 ± 0.03 mg/kg (20% above EU MPL)
- Plectropomus leopardus: 0.06 ± 0.01 mg/kg (15% above EU MPL)
- Lethrinus nebulosus: 0.08 ± 0.01 mg/kg (25% above EU MPL)
Cadmium (Cd):
- O. niloticus: 0.04 ± 0.01 mg/kg (20% above EU MPL)
- M. cephalus: 0.08 ± 0.02 mg/kg (65% above EU MPL)
- L. niloticus: 0.13 ± 0.02 mg/kg (15% above EU MPL; highest)
- E. tauvina: 0.11 ± 0.02 mg/kg (65% above EU MPL)
- P. leopardus: 0.07 ± 0.01 mg/kg (40% above EU MPL)
- L. nebulosus: 0.03 ± 0.01 mg/kg (5% above EU MPL)
Arsenic (tAs):
- O. niloticus: 0.13 ± 0.01 mg/kg
- M. cephalus: 0.21 ± 0.02 mg/kg
- L. niloticus: 0.25 ± 0.04 mg/kg
- E. tauvina: 1.13 ± 0.06 mg/kg (highest)
- P. leopardus: 1.09 ± 0.07 mg/kg
- L. nebulosus: 1.03 ± 0.04 mg/kg
Note: arsenic is reported as total arsenic (tAs) by AAS without HPLC speciation; values for marine species are expected to contain a large proportion of organic arsenobetaine.
Mercury (tHg):
- O. niloticus: 0.07 ± 0.01 mg/kg
- M. cephalus: 0.27 ± 0.03 mg/kg
- L. niloticus: 0.42 ± 0.05 mg/kg (30% of samples above EU MPL)
- E. tauvina: 0.12 ± 0.01 mg/kg
- P. leopardus: 0.19 ± 0.03 mg/kg
- L. nebulosus: 0.13 ± 0.02 mg/kg
Aluminum (Al):
- O. niloticus: 2.62 ± 0.18 mg/kg
- M. cephalus: 2.95 ± 0.26 mg/kg
- L. niloticus: 3.35 ± 0.19 mg/kg (highest)
- E. tauvina: 2.11 ± 0.29 mg/kg
- P. leopardus: 1.53 ± 0.11 mg/kg
- L. nebulosus: 1.38 ± 0.12 mg/kg
LODs (µg/g wet weight): Pb 0.01, Cd 0.005, As 0.02, Hg 0.01, Al 0.10. CRM DORM-3 used for QA.
Methods (brief)
Graphite furnace AAS (PerkinElmer PinAAcle 900T) for Pb, Cd, Al. Cold vapor AAS for Hg. HNO3/HClO4 wet digestion. QA via DORM-3 (NRC Canada). All concentrations wet weight. Arsenic method was AAS without speciation; tAs values for marine species reflect predominantly organic arsenicals. EDI and HQ calculated per US EPA RfD values; FIR 48.57 g/day for Egyptian adults.
Implications
Certification: Pb and Cd exceedances of EU MPLs in all six Egyptian commercial fish species, despite HI<1 at current consumption rates. The iAs vs. tAs distinction is critical for interpreting As values for marine fish. Courses: Illustrates that EU regulatory exceedances can coexist with sub-threshold hazard index values when exposure is consumption-rate dependent. App: Supports species-specific and geography-specific risk differentiation for Nile/Egyptian fish sources.