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Hijiki Seaweed

A specific sea vegetable used in Japanese cooking.

51Moderate burden · out of 100
Cleaner swapNori, wakame or kombu, which do not carry the same finding

How this score is built

  1. 100Start
  2. 67.8Chemical hazard 7 × 4.6−32.2
  3. 61Everyday exposure 2 × 3.4−6.8
  4. 51Persistence 4 × 2.6−10.4, then rounded to 51
  5. ModerateThe band51 sits in 40–59.

What each input rests on

The three ratings behind the score, and the studies each rests on
InputRatingEvidence
Chemical hazard7/10

  • EFSA's contaminants panel found chronic dietary inorganic arsenic linked to cancers of the skin, bladder and lung, treated it as a genotoxic carcinogen, and judged that adult exposure margins (2 to 0.4 for average consumers) raise a health concern.

    Update of the risk assessment of inorganic arsenic in food · EFSA J 2024

    DOI 10.2903/j.efsa.2024.8488 · PMID 38239496 · Abstract · read 2026-10-09

Everyday exposure2/10

  • Of 31 retail seaweed samples of five varieties, inorganic arsenic was found only in the nine hijiki samples, at 67-96 mg/kg; the other types were all below 0.3 mg/kg.

    Arsenic in seaweed--forms, concentration and dietary exposure · Food Chem Toxicol 2007

    DOI 10.1016/j.fct.2007.01.007 · PMID 17336439 · Abstract · read 2026-10-09

Persistence4/10unsourced input

Ratings are editorial. A study listed here supports the rating; it did not compute it. How the index is built

What this means for you

The chemical-hazard rating is what drives the score down. Food-safety agencies in several countries advise against eating hijiki specifically, after testing found inorganic arsenic at levels far above other edible seaweeds. This is unusual among sea vegetables — the common alternatives are not implicated.

Evidence strength: strong

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