Tolkou, Toubanaki & Kyzas 2023 — As, Cr, Cd, Pb, Hg in fish: a four-continent literature review

Tolkou, Toubanaki & Kyzas (2023) present a narrative review of arsenic, chromium, cadmium, lead, and mercury concentrations in fish muscle tissues across 4 continents (Asia, Europe, Africa, Latin America), 13 countries, and more than 50 fish species, drawing on primary studies published between 2003 and 2023. The review compiles per-species mean concentrations in mg/kg, compares them against FAO/WHO permissible limits (As 0.1; Cr 0.15; Cd 0.05; Pb 0.5/2.0; Hg 0.5 mg/kg), and reports the overall sequence of accumulation in fish as As > Cr > Pb > Cd > Hg. Asia is identified as the region with the most frequent exceedances across multiple analytes, while in Europe and Africa the principal exceedance is for arsenic, predominantly in marine fish.

Key numbers

FAO/WHO permissible reference values applied throughout the review (mg/kg, fish): As 0.1; Cr 0.15; Cd 0.05; Pb 0.5 (and 2.0 for some categories); Hg 0.5.

Asia — Dhaleshwari River, Tangail, Bangladesh (six species; Aminul Ahsan 2018): Cd 0.002–0.019, Cr 0.046–0.159, As 0.016–0.128, Pb 0.091–0.234, Hg 0.004–0.012 mg/kg across species. The species the review identifies as exceeding FAO/WHO limits are: As, Pb, and Hg in Metapenaeus tenuipes (syn. Spinulatus, shrimp; As 0.128, Pb 0.231, Hg 0.012); Cd in Amblyceps mangois (0.063); Cr in Mastacembelus armatus (0.159). The review’s body text also names As 0.061 in Puntius puntio (Puntio barb) — below the 0.1 mg/kg As limit — among the “most contaminated species” framing, though Table 2 shows shrimp As (0.128) is higher. Sequence: Pb > As > Cr > Cd > Hg.

Asia — Southern Bangladesh (Resma et al.): Cr (in drinking-water units) 0.590, 0.577, 0.623 mg/L for Oreochromis niloticus, Pangasius pangasius, Labeo rohita respectively; As 0.042 / 0.045 / 0.035 mg/kg; Cd 0.004 / 0.006 / 0.004 mg/kg. Cr units annotated by the review as *** = drinking-water 1.0 mg/L reference, distinguishing from the fish-tissue Cr standard of 0.15 mg/kg.

Asia — Buriganga River, Dhaka, Bangladesh (Real et al., on Heteropneustes fossilis): Cd 0.040, Pb 1.040, Cr 0.330 mg/kg — all above FAO/WHO limits for fish.

Asia — Bay of Bengal, Bangladesh (Mamun et al., 2022): in Coilia dussumieri, As 1.330, Cr 0.630, Cd 0.130, Pb 0.230 mg/kg; in Sardinella fimbriata, As 3.930, Cr 1.570, Cd 0.060, Pb 0.930 mg/kg.

Asia — Coastal Vietnam (Ngoc et al. 2020): in Channa argus (snake-headed fish), Cd 2.300, Cr 2.120, As 1.180, Pb 0.080 mg/kg; in Pangasianodon hypophthalmus (catfish), Cr 2.250, As 1.660, Cd 1.060, Pb 0.100 mg/kg.

Asia — Jeddah, Saudi Arabia (Aljabryn 2022): Pb 5.050 in Plectropomus pessuliferus (Roving coral grouper) and Pb 2.800 in Epinephelus summana (Summan grouper) — both substantially above FAO/WHO Pb limit. As 0.235 (P. pessuliferus), 0.220 (E. summana). Cd 0.000 (not detected) in all five species reviewed.

Asia — Tercan Dam Lake, Erzincan, Turkey (Güneş et al. 2019): Capoeta umbla (Tigris scraper) Cr 2.455, Pb 2.074, As 0.186 mg/kg — Cr and Pb well above limits. Ctenopharyngodon idella (Grass carp) As 0.774, Cr 0.049, Pb 0.455 mg/kg. Cyprinus carpio (Common carp) As 0.383, Cr 0.918, Pb 0.534 mg/kg. Luciobarbus capito (Bulatmai barbel) As 0.124, Cr 0.398, Pb 0.090 mg/kg.

Asia — Hangzhou Bay, China (Noman et al. 2022, six species): metal-by-organism sequence reported as As > Cr > Cd > Pb > Hg. Highest As 0.350 in Cynoglossus joyneri (Red tongue sole); highest Cd 0.070 in Harpadon nehereus (Bombay duck). All values within national and international guideline ranges, but children flagged as vulnerable to carcinogenic risk (CR index) from As and Cd via fish consumption.

Asia — Karachi Coast, Pakistan: in Thunnus spp., Cr 0.350, Cd 0.710, Pb 0.270 mg/kg (Cd > Cr > Pb > Hg > As order); in Rastrelliger kanagurta (Indian mackerel) Cr 0.370, Cd 0.310, Pb 0.320 mg/kg (Cr > Cd > Pb > Hg > As order).

Europe — Adriatic Sea coast, Italy (Sepe et al. 2003, six species): values for Cd, Cr, Pb only. Highest Cd 0.020 (Engraulis encrasicolus), Cr 0.083 (E. encrasicolus), Pb 0.046 (E. encrasicolus). All below FAO/WHO limits.

Europe — Andalusia, Southern Spain (Olmedo et al. 2013): As 0.561 in Sardina pilchardus, 0.427 in Mullus surmuletus (above FAO/WHO 0.1 mg/kg As limit). Pb highest at 0.117 in Sepia officinalis (cuttlefish). Hg 0.091 in Lepidorhombus boscii (Four-spotted megrim) and 0.067 in Mullus surmuletus (Striped red mullet) — both below the 0.5 mg/kg Hg limit but the highest in the European table. Cd low to nil across species.

Europe — Žitava River, Slovakia (Tóth et al. 2012, Cyprinus carpio): Cd 0.060, Pb 0.140, Hg 0.020 mg/kg.

Europe — Baltic Sea, Gdansk, Poland (Polak-Juszczak & Szlinder Richert 2021): As 0.390 (Gadus morhua callarias L., Baltic cod), 0.636 (Sprattus sprattus, European sprat), 0.460 (Clupea harengus membras, Baltic herring), 0.588 (Platichthys flesus, European flounder) — all above the 0.1 mg/kg As limit. European sprat had the highest total As content.

Africa — Gulf of Guinea, West Africa (Nyarko et al. 2023, four species): As 8.480 mg/kg and Cd 0.027 mg/kg in Penaeus notialis (Southern pink shrimp) — the highest As reported anywhere in the review. As 1.870 (Dentex angolensis), 1.560 (Sardinella maderensis), 0.820 (Sphyraena sphyraena). Hg 0.137 in Dentex angolensis, 0.063 in Sphyraena sphyraena. Pb below detection limit in all species examined.

Latin America — Bahía Blanca estuary, Argentina (La Colla et al. 2017, six species): Cr 0.450 in Cynoscion guatucupa (Stripped weakfish) and 0.250 in Odontesthes argentinensis — both above the 0.15 mg/kg Cr limit. Pb below method detection limits in all species.

Cross-continent exceedance proportions (Figure 6, percentage of studies reviewed above FAO/WHO limits): Asia — As ~57%, Cr ~35%, Cd ~24%, Pb ~24%; Europe — As ~53%; Africa — As 100% of studies; Latin America — Cr ~33%. Hg did not exceed the 0.5 mg/kg limit in any continent or case study in the review.

By water type, As exceedances were concentrated in marine fish in Europe and Africa, and slightly more so in freshwater fish in Asia. The review reports the overall accumulation sequence in fish as As > Cr > Pb > Cd > Hg.

Methods (brief)

This is a narrative literature review, not a primary measurement study. The authors compiled per-species mean concentrations from cited studies (references [5,6,9,20,28,33,34,43–56] in the paper) and tabulated them in Tables 2–5 by continent. The review does not perform independent measurement, meta-analytic pooling, or statistical inference; it presents per-study values side by side and compares each to FAO/WHO permissible limits.

The methods section of the review summarizes analytical techniques used across the cited studies: As, Cr, and Cd in most studies determined by ICP-MS, HPLC/ICP-DRC-MS (for As speciation in some), ICP-OES, graphite-furnace AAS (GFAAS), or flow-injection hydride generation (FIAS). Pb measured by electrothermal AAS (ETAAS) or AAS. Hg measured by single-purpose atomic absorption spectrometer AMA-254. Sample preparation across cited studies used hydrogen peroxide / hydrochloric acid digestion, microwave-assisted digestion, or H₂O₂ + microwave digestion; Milli-Q water for digest dilution.

Values throughout the tables are reported in mg/kg (= ppm) in fish muscle tissue, except where the review annotates Cr values from one Bangladesh study as drinking-water concentrations in mg/L (Resma et al. for Oreochromis niloticus, Pangasius pangasius, Labeo rohita; *** annotation in Table 2). The review does not separate inorganic from total arsenic, nor methylmercury from total mercury, in any tabulated value.

Reviewed coverage: 4 continents (Asia, Europe, Africa, Latin America), 13 countries (Spain, Italy, Slovakia, Poland, China, India, Pakistan, Turkey, Bangladesh, Vietnam, Saudi Arabia, Guinea, Argentina), >50 fish species. No PRISMA protocol, no search-string disclosure, no inclusion/exclusion criteria stated.

Implications

Certification: Contributes per-species occurrence data for marine and freshwater fish across four continents. Useful as an aggregated entry point into the primary literature on Cr in Tercan Dam Lake freshwater fish, As in Baltic sprat and herring, As in Gulf of Guinea shrimp, and Pb in Saudi Arabian grouper. The review highlights that the Hg limit (0.5 mg/kg) is not exceeded in any of the >50 species tabulated, while As and Cr limits are routinely exceeded in marine and freshwater fish from several geographies.

Courses: Illustrates the geographic heterogeneity of heavy-metal contamination in fish — the same species can show order-of-magnitude differences in As, Cr, or Pb depending on water body and proximity to industrial, agricultural, or geogenic sources. Demonstrates the limits of single-region literature for global occurrence claims.

App: Contextual signal that fish marketed from Asian (especially Bangladeshi and Vietnamese), Saudi Arabian, and West African waters carry elevated As and Pb risk in primary literature; European and Latin American fish show narrower exceedance profiles concentrated on As (Europe) and Cr (Latin America). The Hg signal is uniformly below the 0.5 mg/kg limit across the review.

Wiki pages this source may touch

• arsenic-total
• chromium
• cadmium
• lead
• mercury-total
• fish
• freshwater-fish
• seafood
• shellfish
• fresh-fish
• fish-freshwater
• fish-marine-non-predatory
• fish-marine-predatory

Verification notes

• Speciation: the review reports all values as totals (As, Cr, Cd, Pb, Hg) with no inorganic-vs-organic separation; this page uses tAs and tHg accordingly, and Cr (not Cr-VI) per CLAUDE.md Part 14.
• Cr units in Resma et al. (Southern Bangladesh) are flagged in the source table as *** = drinking-water values in mg/L, not fish-tissue values in mg/kg. The Key numbers section preserves that distinction explicitly.
• The Pb FAO/WHO limit footnote in the source tables shows “0.5/2.0” (the lower for general fish; 2.0 for some categories); the page preserves the source’s exact notation.
• Shrimp (Penaeus notialis, Metapenaeus tenuipes/Spinulatus) is included in some tables; this page uses shellfish as the broad-scope ingredient/matrix slug for crustacean entries rather than creating species-level slugs.
• This is a narrative review (B-tier), not a PRISMA systematic review; values are tabulated per cited primary study without pooling or meta-analysis. Treated as a literature entry point rather than as an evidence source on its own.
• Folder placement (02_Marine_Nonpredatory) is narrower than the paper’s actual scope, which spans marine non-predatory (sardine, herring, sprat, anchovy, sole, flounder), marine predatory (grouper, snakehead, barracuda, smoothhound shark, mackerel), and freshwater (carp, tilapia, catfish, scraper, rohu). Frontmatter products list all three subcategories plus the umbrella fresh-fish per the broad-scope rule.
• Audit subagent (2026-06-03) flagged the Dhaleshwari “Highest As 0.061 (Puntius puntio)” framing as inconsistent with Table 2 (Metapenaeus tenuipes shrimp As 0.128 is higher than Puntius 0.061) and with the source’s own p. 8 statement that Metapenaeus tenuipes exceeded the As, Pb, and Hg limits. Verified against source — corrected to identify the species the review attributes as limit-exceeding (shrimp for As/Pb/Hg; Amblyceps mangois for Cd; Mastacembelus armatus for Cr), while preserving the Puntius puntio 0.061 figure as the body-text reference it actually is.
• Audit subagent (2026-06-03) flagged “Asia — As >50% of studies” as a loose paraphrase of Figure 6’s ~57% bar. Tightened to “~57%” to match the figure directly.

Page history

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