Shaughnessy et al. 2023 - metals in wild and farmed New England sugar kelp
Shaughnessy and coauthors measured arsenic, cadmium, lead, and mercury in wild and farmed sugar kelp from New England. The paper is directly relevant to seaweed foods because it compares farmed and wild material, blade position, geography, and food-safety standards. Cadmium and total arsenic were the main regulatory-concern signals, while inorganic arsenic, lead, and mercury were lower relative to the standards discussed by the authors.
Key numbers
The paper reports that Cd and total arsenic consistently reached levels of regulatory concern in some sugar-kelp material. It also reports that iAs, Pb, and Hg did not approach regulatory-concern levels in the same way as total As and Cd. The methods section states that the authors compared dry-weight concentrations to a 7 g serving of dried sugar kelp and wet-weight concentrations to a 57 g serving of seaweed salad.
The regulatory comparison table reproduced in the paper includes the following seaweed-specific or food-supplement reference values:
| Analyte | Reference level discussed in paper |
|---|---|
| Total arsenic | 40 mg/kg in feed reference |
| Inorganic arsenic | 2 mg/kg in feed reference; 10 ug/day Prop 65 NSRL |
| Cadmium | 1 mg/kg feed reference; 3.0 mg/kg wet weight food-supplement reference |
| Lead | 10 mg/kg feed reference; 3.0 mg/kg wet weight food-supplement reference |
| Mercury | 0.1 mg/kg feed reference; 0.1 mg/kg wet weight food-supplement reference |
Methods (brief)
The study collected farmed sugar-kelp blades from commercially permitted industry collaborators and wild sugar-kelp beds in Massachusetts. Samples were compared by site and blade location. The authors used contaminant-source proximity, blade position, and food-safety standards to interpret the measured concentrations.
Implications
Certification: Strong A-tier evidence for seaweed-kelp foods and algae/seaweed-based supplements, especially for Cd and arsenic routing. The US/New England geography should remain explicit.
Courses: Useful for explaining within-blade and site-level variation in seaweed metals.
App: Supports a high-priority seaweed risk flag after synthesis, with species and region retained.
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Verification notes
The PDF text extraction surfaced narrative and regulatory comparisons but not all supplementary sample-level tables. This page preserves the routeable matrix and high-level numerical standards; audit should pull supplementary table values before benchmark-pool use.
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.
| Commit | Date | Description |
|---|---|---|
| 50ec0f0 | 2026-05-30 | ingest auto-fetched 2026-05-30 2145 batch 1: 10 source pages |