Suzuki 2022 - Nano-sized mercury particles in seafood

Suzuki and colleagues measured nano-sized mercury-containing particles (NP-Hg), total mercury (T-Hg), methylmercury (MeHg), and selenium in raw fish and shellfish purchased in Japan. The study reports occurrence data for seafood groups and uses Japanese consumption data to estimate dietary exposure to T-Hg, MeHg, and NP-Hg. NP-Hg is treated as a separate nanoparticulate mercury finding in this page, not as a substitute for T-Hg or MeHg.

Key numbers

Ninety samples from eight raw seafood groups were purchased in Japan between 2019 and 2020: tuna and swordfish n = 44; salmon and trout n = 10; horse mackerel and sardine n = 4; sea bream and flounder n = 2; other raw fishes n = 13; squid and octopus n = 11; shellfish n = 3; and shrimp and crab n = 3.

Table 2 reports mean consumption rates, concentrations, and estimated dietary exposure for the Japanese population age >1 year:

The results text states that mean T-Hg concentrations were highest in the tuna-swordfish group at 656 ng/g as Hg and lowest in the shellfish group at 8.75 ng/g. Mean MeHg concentrations followed the same pattern, with tuna-swordfish at 631 ng/g as Hg and shellfish at 4.05 ng/g as Hg.

For NP-Hg, the abstract reports higher particle number concentrations in tuna-swordfish than shellfish, 17.7 x 10^7 versus 1.2 x 10^6 particles/g. The results text reports mean particle mass concentration highest in tuna-swordfish at 12.0 ng/g as Hg and lowest in squid-octopus at 0.10 ng/g as Hg.

A representative tuna muscle sample in Figure 2 had T-Hg 2221 ng/g as Hg, MeHg:T-Hg ratio 91.3%, 2486 particles detected over 300-s, CPM 90.5 ng/g as Hg, and CPN 1.1 x 10^9 particles/g. Assuming detected NP-Hg were spherical HgSe, mean particle size was estimated at 29.0 nm and maximum particle size at 89.7 nm.

The abstract and discussion report mean dietary exposure estimates of NP-Hg 0.067 μg/person per day, T-Hg 5.75 μg/person per day, and MeHg 5.32 μg/person per day. The paper also reports mean dietary exposure to NP-Hg as 1.2 ng/kg body weight (BW) per day, using a 55 kg body weight.

Methods (brief)

Raw fish and shellfish samples were purchased in Japan in 2019-2020. Shellfish were homogenized with internal organs because they are usually eaten that way; all other fish samples used muscle tissue only. T-Hg was determined by thermal decomposition mercury analyzer (MA-3000; Nippon Instruments), MeHg by HPLC-ICP-MS after 10% TMAH extraction, selenium by ICP-MS after microwave-assisted digestion, and NP-Hg by spICP-MS after pancreatin/lipase enzyme extraction and ultrafiltration. The paper reports a single-particle mass LOD of 0.038-0.049 fg, equivalent to a particle-diameter LOD of 20.9-22.9 nm, and notes that NP-Hg below that size could make exposure estimates an underestimate.

Implications

This source contributes Japanese-market seafood occurrence data for T-Hg, MeHg, and nanoparticulate mercury across mixed fish and shellfish groups. The routing value is strongest for seafood mercury speciation because T-Hg and MeHg are both measured and reported separately, while NP-Hg is a distinct nanoparticle finding rather than a replacement for either mercury species. The exposure table is useful context, but downstream pooling should preserve the source units and the paper’s group-level seafood categories.

Verification notes

• PDF text extracted with pdftotext -layout; title page, methods, Figures 1-5 captions, Table 1, Table 2, discussion, and conclusion were readable.
• DOI 10.1016/j.envpol.2022.119555, raw handle MFK_presence-of-nano-sized-mercury-containing-particle, and cite-key checks found no existing source page before creation.
• Table 2 values were checked against the extracted text. Units are preserved as ng/g as Hg, μg/day as Hg, particles/g, nm, and ng/kg body weight (BW) per day; no conversion was performed.
• Speciation: the page keeps T-Hg and MeHg separate. NP-Hg is reported as nano-sized mercury-containing particles, inferred by the authors as likely HgSe under stated assumptions; it is not collapsed into T-Hg, MeHg, or inorganic mercury frontmatter.
• Brand firewall: samples were grouped by seafood type and no product brands were reported.
• Frontmatter product and ingredient slugs were checked against docs/gpt-collaboration/taxonomy-snapshot.md; no new slug was invented. There is no closed-vocabulary metal/frontmatter slug for NP-Hg or HgSe nanoparticles, so they remain documented in the body.

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.