Rakib et al. 2021 — Macroalgae metals in Bangladesh

Rakib et al. measured trace elements in 10 macroalgae species from the Cox’s Bazar and Saint Martin’s Island coastal region of Bangladesh. The source is routeable for seaweed and kelp foods because several sampled species are described as edible or locally consumed, and the paper reports dry-weight and converted wet-weight concentrations for Pb, total As, and Cr.

Key numbers

• Sample frame: 10 seaweed species, each prepared in triplicate, from Cox’s Bazar and Saint Martin’s Island; sample labels covered red, brown, and green algae.
• Mean concentrations across the 10 species were reported as Pb 2.6 mg/kg dry weight and 0.39 mg/kg wet weight, total As 3.4 mg/kg dry weight and 0.50 mg/kg wet weight, and Cr 1.15 mg/kg dry weight and 0.17 mg/kg wet weight. The table label order is awkward, but the methods text says dry-weight concentrations were converted to wet-weight values using 85 percent water content, so the larger values are treated as dry weight.
• Species-level maxima highlighted in the results were Pb 10.63 mg/kg in sample B6, followed by 4.50 mg/kg in R4 and 4.24 mg/kg in B5; total As 11.89 mg/kg in B5 and 10.75 mg/kg in B6; and Cr 3.64 mg/kg in R4, 1.94 mg/kg in R3, and 1.90 mg/kg in B6.
• Method detection limits were 0.12 mg/kg for Pb, 0.02 mg/kg for As, and 0.29 mg/kg for Cr.
• The exposure calculation used a seaweed intake of 5.2 g/person/day and a 70 kg adult body weight.

Methods (brief)

Samples were rinsed, dried to constant weight at 60 degrees C, ground, pelletized, and analyzed by energy-dispersive X-ray fluorescence. The authors used NIST orchard leaf material for calibration and NIST 1570a spinach as a validation material; reported relative error was less than 10 percent for the validation elements. The paper reports elemental arsenic by EDXRF, so the arsenic value is total arsenic, not inorganic arsenic.

Implications

Certification: The source can contribute to seaweed or kelp food occurrence pools for Pb, total As, and total Cr when Bangladesh-market or South Asia coastal seaweed evidence is in scope. It should not be pooled into US-market seaweed standards without a jurisdiction crosswalk.

Courses: This is a useful case for explaining why seaweed risk differs by species, coastline, and basis, and why total arsenic cannot be read as inorganic arsenic.

App: The data support a seaweed ingredient signal for Pb, total As, and Cr with Bangladesh-specific context.

Microbiome: No direct microbiome endpoint was measured.

Wiki pages this source may touch

• seaweed
• seaweed-kelp-foods
• lead
• arsenic
• chromium

Verification notes

• The file arrived under a mineral-water/Pb wishlist filename, but the PDF is a seaweed biomonitoring and food-exposure paper; it was routed by PDF content, not filename.
• The paper’s table heading places “wet weight” before “dry weight”, but the surrounding text and conversion formula identify the larger values as dry-weight concentrations and the smaller values as wet-weight conversions. This page preserves that interpretation explicitly.
• Arsenic is routed as total arsenic because the EDXRF method does not speciate inorganic arsenic.

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.