Measurement / residue studyindependent cross-checkfull text checked★ key study I-FSH-14 in-depth review
Metals in Egyptian market sea fish (2023-2024)
Carcinogenic and non-carcinogenic health risks associated with heavy metal exposure in commonly consumed marine fish in Egypt.
Overview
Elshebrawy HA et al.. Sci Rep 2026 · PMID 42632867 · DOI 10.1038/s41598-026-67201-w
Up to a fifth of mullet, sardine and mackerel samples exceeded mercury limits; heavy eaters could exceed safe intake for mercury and lead (arsenic risk is probably overestimated).
Does the study support the specific claim? No · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Measure metals.
- How was the study done?
AAS.
- How many people, animals or samples were studied?
250 fish.
- What was actually found?
Mercury above limits in 9-20% of samples, lead in 20-58%; mercury intake from mullet slightly above the tolerable level (111%) even at average consumption.
- How large was the observed effect?
THQ > 1 for Hg, As.
- What do the results mean in everyday life?
Sea fish is not automatically clean.
- What are the study's limitations?
Total arsenic only (overestimates cancer risk); raw fish; one city; wild/farmed origin unknown; mackerel imported from Norway/Netherlands.
- What does it say about Elawady's specific claim?
Contradicts 'wild sea fish is cleanest'.
- Do the results apply to Germany and Europe?
Low.
- What can explicitly not be concluded from this study?
Health outcomes; differences between farmed and wild fish.
Scientific in-depth review
1. Full reference
- Authors
- Elshebrawy HA et al.
- Journal
- Sci Rep
- Year
- 2026
- Identifier
- PMID 42632867 DOI 10.1038/s41598-026-67201-w
- Verification
- verified – PubMed efetch 2026-10-25
- Retracted
- no
- Corrections
- none
- Extent checked
- full text
- Conflicts of interest and funding
Open access funding by the Science, Technology & Innovation Funding Authority (STDF) with the Egyptian Knowledge Bank; authors declare no competing interests.
2. Research question
Hg, As, Pb, Cd in commonly consumed marine fish in Egypt and consumer risk
3. Study design and population
- Study design
- Measurement / residue study – Retail market survey of heavy metals (AAS) in three marine fish species with deterministic health-risk assessment (EDI vs PTDI/BMDL, THQ/TTHQ, cancer risk)
- Population
Flathead grey mullet (Mugil cephalus, n=50), round sardinella (Sardinella aurita, n=100) and Atlantic mackerel (Scomber scombrus, n=100; imported frozen, mainly from Norway and the Netherlands per vendors) from six retail outlets in East Mansoura
- Country
Egypt
- Period
Aug 2023-Mar 2024
- Sample size
250 fish (10 sampling occasions; 5 randomly selected outlets per occasion)
- Inclusion and exclusion criteria
Commercially available fish; muscle analysed raw; origin (wild/farmed, fishing area) of mullet and sardine not individually documented (market supply from Mediterranean coastal governorates or imports)
4. Methods and endpoints
- Exposure / intervention
Species
- Comparator
FAO, EOS (Egypt) and FSANZ maximum permissible limits; JECFA/EFSA PTDI/BMDL; US EPA RfD and cancer slope factors
- Endpoints
Hg, As, Pb, Cd concentrations (ug/g ww); % exceeding limits; EDI for general (57.09 g/day) and high consumers (200 g/day), 70 kg body weight; THQ, TTHQ, cancer risk
- Statistical methods
Descriptive statistics and between-species comparisons; validation with CRMs (recoveries 95.5-100.6%), linearity, precision, LOD/LOQ
5. Actual results
- Results
Mean (ug/g ww) Hg/As/Pb/Cd: mullet 0.313/2.13/0.194/0.018; sardine 0.131/1.65/0.472/0.021; mackerel 0.196/0.98/0.370/0.025. Exceedance of limits (depending on standard): Hg 9-20%, As 22-56%, Pb 20-58%; Cd within limits. General population: only Hg EDI from mullet exceeded the PTDI (111%). High consumers: Hg EDI 388.7% (mullet), 162.6% (sardine), 243.5% (mackerel) of PTDI; As above BMDL for mullet (203%) and sardine (157%); Pb above for sardine (214.3%) and mackerel (167.8%). THQ for Hg and As >1; TTHQ 8.4/5.7/4.35 (general) and 29.43/19.84/15.26 (high consumers). Cancer risk for As (using total As) 1.20E-03 to 9.14E-03, above 1.0E-04; Pb and Cd within limits.
- Absolute risks
Modelled lifetime cancer risk for arsenic 1.20E-03 to 9.14E-03 based on total arsenic (authors note this may substantially overestimate risk); no observed health outcomes
- Authors' conclusion
The fish contained high heavy-metal concentrations, with many samples exceeding permissible limits for As and Pb; potential non-carcinogenic risks and arsenic cancer risk, particularly for high consumers; regular monitoring and pollution control needed. Authors acknowledge raw-tissue analysis and lack of arsenic speciation may overestimate risk.
6. Strengths
- Repeated random retail sampling over 8 months, 250 fish
- Validated AAS with CRMs
- Two consumption scenarios
7. Weaknesses
- Total arsenic used for cancer risk; authors state more than 90% of As in marine fish is organic and only 0.02-11% inorganic, so cancer risk is substantially overestimated
- Hg measured as total Hg (treated as MeHg)
- Raw muscle; cooking not considered
- One city; fish origin and wild/farmed status not documented for mullet and sardine; mackerel imported from Norway/Netherlands
- THQ/TTHQ are screening indices; summing across metals assumes additivity
- Some exceedance figures depend strongly on which standard is applied
8. Risk of bias
- Orienting tool
- No standard tool fits (exposure measurement / risk assessment); structured validity judgement
- Type of assessment
- structured assessment based on the full text by a single reviewer (no formal double review)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Single-reviewer structured judgement based on the full text; not formal (needs two independent reviewers). Arsenic risk estimates should be regarded as upper bounds.
| Domain | Judgement | Rationale |
|---|---|---|
| Sampling / representativeness | some concerns | Random outlet selection in one city; origin of fish largely unknown; mackerel imported. |
| Analytical measurement | low | AAS with CRM recoveries 95.5-100.6% and validation. |
| Risk characterisation | high | Cancer risk from total arsenic with inorganic-arsenic slope factor; authors acknowledge substantial overestimation. |
| Reporting | low | Detailed tables; limitations stated. |
Full-text review (25 October 2026): Added species sample sizes, sampling scheme, mackerel imported from Norway/Netherlands, EDI percentages vs PTDI, author-acknowledged arsenic overestimation and cooking limitation, funding (STDF/EKB) and COI; structured validity domains (overall unchanged).
9. Assessment of the statistical interpretation
Hg findings (mean 0.131-0.313 ug/g; EDI 111% of PTDI for mullet at average intake) are the most robust signal; arsenic THQ and cancer-risk values rely on total As and are likely inflated by orders of magnitude; Pb exceedances depend on the standard used.
10. Relevance to the specific claim
C-FSH-14 (wild sea fish not automatically clean).
11. Independent contrary findings
12. Transferability to Germany and Europe
Low.
13. Overall methodological judgement
Signals that commonly eaten marine fish sold in an Egyptian city (including mullet and imported mackerel) carry mercury and lead at levels of potential concern for high consumers; arsenic risks are overstated. Contradicts the notion that sea fish are automatically the 'cleanest' food, but the origin (wild vs farmed) of the mullet is not documented, so it cannot compare farmed and wild fish.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | moderate |
| Directness | direct |
| Reproducibility | unknown |
| Consistency with the overall evidence | mixed |
| Regional transferability | low |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Arsenic speciation; documented origin (wild vs farmed, fishing area); larger predatory species (grouper, tuna) named in the claim.