Total and inorganic arsenic contents in seaweeds: Absorption, accumulation, transformation and toxicity

Overview

Ma and colleagues reviewed published total arsenic and inorganic arsenic measurements in seaweeds, grouping the literature by Rhodophyta, Phaeophyta, and Chlorophyta. This is secondary evidence: it compiles prior studies and does not add new sample measurements. The values below are useful for seaweed/kelp food and algae/seaweed supplement context, but downstream occurrence pooling should trace and de-duplicate the underlying primary studies.

Key numbers

All concentration values below are reported by the review as mg kg-1 DW; no unit conversion was performed. The review states that records were collected from published studies available up to June 2017 and that the same seaweed species collected from different geographic zones was treated as a different datum.

Table 1 summary by phylum:

The abstract and Section 3 report that total arsenic (tAs) in the top 10 Phaeophyta species is over 100 mg kg-1 DW, while the top 7 Rhodophyta species range from 20 to 50 mg kg-1 DW and the top 3 Chlorophyta species range from 10 to 15 mg kg-1 DW. Section 3.2 reports that Phaeophyta inorganic arsenic (iAs) is significantly higher than Rhodophyta and Chlorophyta (P<0.05), while Rhodophyta and Chlorophyta do not differ significantly (P>0.5).

Table 2 high-tAs species:

The Table 2 footnote defines high-tAs species thresholds as above 100, 20, and 10 mg kg-1 DW for Phaeophyta, Rhodophyta, and Chlorophyta, respectively.

Table 3 high-iAs species:

The Table 3 footnote defines high-iAs species thresholds as above 50, 1, and 0.3 mg kg-1 DW for Phaeophyta, Rhodophyta, and Chlorophyta, respectively; the extracted footnote prints AsT in this sentence, but the table title and body are for inorganic arsenic.

Additional source-reported context:

• The review states that typical ocean-water arsenic is 1 to 3 µg l-1, with an average of 1.7 μg l-1.
• It states that seaweed tAs levels are approximately 1,000-50,000 times higher than ocean water, depending on species.
• It reports that most species of Rhodophyta, Phaeophyta, and Chlorophyta have tAs below 30, 100, and 20 mg kg-1 DW, respectively.
• It cites one Sargassum sinicola case near Gulf of California hydrothermal venting as above 600 mg kg-1; this is environmental context from a cited study, not a Table 1-3 occurrence summary row.
• It reports that arsenosugars make up >85% of soluble arsenic in most species, citing Rose et al. 2007 and Kalia and Khambholja 2015.

Methods (brief)

This is a peer-reviewed literature review, not a primary measurement study. The authors compiled published seaweed arsenic studies available up to June 2017, summarized total and inorganic arsenic by phylum, and listed high-tAs and high-iAs species with the methodology and cited primary reference where available. Samples of the same species from different geographic zones were treated as separate data points so that each species-zone record corresponded to one datum. Analytical methods in the compiled studies include AFS, ICP-MS, HPLC-ICP-MS, FI-HG-AAS, AAS, GS, HG-AFS, ICP-OES, and INAA.

Implications

This source supports seaweed/kelp food and algae/seaweed supplement context by identifying phylum- and species-level patterns in total arsenic and inorganic arsenic. The review’s most relevant routing signal is that Phaeophyta values, especially hijiki, Sargassum piluliferum, Laminaria spp., and several brown algae, carry much higher secondary-summary iAs than Rhodophyta or Chlorophyta. Because the paper aggregates prior literature and several underlying primary sources are separately ingested in the wiki, these values should not be pooled as independent occurrence measurements without source-level de-duplication.

Related evidence

• Seaweed/kelp foods (nori, wakame, kombu, dulse — as food products)
• Ingredient class — algae/seaweed-based
• Seaweed
• Arsenic, Total
• Arsenic, Inorganic

Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git.