Olmedo 2013 - Andalusia fish and shellfish metals

Olmedo and colleagues measured mercury, cadmium, lead, arsenic, and tin in fresh, canned, and frozen fish and shellfish products commonly consumed in Andalusia, Spain. The study analyzed 485 samples, reported medians with 5th and 95th percentiles in mg/kg wet weight, and performed methylmercury speciation in the high-total-mercury predatory fish subset. Arsenic was measured as total arsenic, not inorganic arsenic.

Key numbers

The study collected samples between 2009 and 2010. Table 2 reports fresh fish and shellfish medians as mg/kg wet weight:

For the highest fresh-fish mercury rows, Table 2 reports cat shark Hg 0.698 (0.153-1.406), swordfish 0.540 (0.177-1.227), tuna 0.470 (0.298-0.779), and blue shark 0.350 (0.238-0.963). For arsenic, the highest fresh medians are shrimp 0.739 (0.388-0.884), sardine 0.561 (0.169-0.959), red mullet 0.427 (0.230-0.729), cat shark 0.340 (0.183-0.450), and clam 0.307 (0.189-0.415).

Table 3 reports canned products as mg/kg wet weight:

Table 3 reports frozen products as mg/kg wet weight: codfish Hg/Cd/Pb/As 0.000/0.002/0.004/0.036; common sole 0.000/0.003/0.544/0.059; hake 0.000/0.001/0.086/0.028; prawn 0.000/0.001/0.033/0.045; shrimp 0.070/0.010/0.004/0.509; and squid 0.000/0.073/0.004/0.044.

The methylmercury speciation section states that no Hg2+ peak was detected in analyzed fish samples and, with Hg2+ LOD set at 0.5 µg/L, more than 99.9% of total mercury in fresh blue shark, cat shark, swordfish, tuna, and canned tuna was inferred to be MeHg.

Table 4 category summaries report total Hg median 0.017 across all 485 samples, with 6 samples above the applicable maximum level (1.24%). The category listed as predatory/specified fish had Hg median 0.237 and P95 0.974. Total Cd median was 0.004, with 3 samples above maximum level (0.62%). Total Pb was reported with lower/upper bounds because 346 samples were below LOD (71.34%), with 25 samples above maximum level (5.15%). Canned-food Sn had lower-bound median 0.000, upper-bound median 0.001, and no samples above the 200 mg/kg maximum level.

The risk-assessment table reports estimated weekly intakes for an average 60 kg person: Hg 63.63 µg/week, Cd 17.57 µg/week, Pb 75.95 µg/week, and Sn 15.40 µg/week. The text estimates inorganic arsenic intake at 0.42 µg/day (2.94 µg/week) by assuming 2% of fish arsenic and 3.5% of shellfish arsenic as inorganic arsenic, but the measured arsenic results themselves are total arsenic.

Methods (brief)

Fresh and frozen seafood samples were collected from the central market of Granada, and canned species were purchased from major supermarkets in Granada. About 0.7 g of edible sample was microwave digested for Hg, Cd, Pb, As, and Sn analysis. Arsenic, total mercury, cadmium, lead, and tin were determined by atomic absorption methods; MeHg speciation used HPLC-ICP-MS after tetramethylammonium hydroxide extraction. Medians and P5-P95 were used because concentrations were non-normal; lower and upper bounds were used when more than 60% of samples were below LOD.

Implications

This source contributes primary wet-weight occurrence evidence for fresh fish, canned fish, frozen fish, and shellfish rows. It is especially important for seafood mercury because it directly checked MeHg speciation in high-Hg predatory fish and found the total-Hg signal to be overwhelmingly MeHg in that subset. Total arsenic and the paper’s modeled inorganic-arsenic intake assumption must remain separate from measured inorganic arsenic data.

Verification notes

• PDF text extracted with pdftotext -layout; title page, methods, Tables 1-5, and discussion were readable. Rendered page /tmp/olmedo-page-05.png was checked to confirm Table 3 layout for canned and frozen products.
• DOI 10.1016/j.envint.2013.05.005, raw handle MFK_olmedo2013, and cite-key checks found no existing source page before creation.
• Table medians, selected P5-P95 ranges, sample count, category summaries, weekly intakes, and MeHg speciation statements were checked against extracted text and rendered table layout. Units are preserved as mg/kg wet weight, mg/kg ww, µg/L, and µg/week; no conversion was performed.
• Speciation: measured arsenic is total arsenic (tAs), not inorganic arsenic. The paper models inorganic-arsenic intake using EFSA assumptions but does not measure inorganic arsenic. Total Hg and MeHg are kept distinct; the page records the source’s direct MeHg-speciation finding for selected high-Hg predatory fish.
• Brand firewall: no sampled product brands are attached to contamination values.
• Frontmatter slugs were checked against docs/gpt-collaboration/taxonomy-snapshot.md. Cephalopod- and crustacean-specific product slugs were not available in the snapshot, so squid, octopus, prawn, and shrimp route through broad shellfish/seafood context.

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.