Identification of some arsenic species in human urine and blood after ingestion of Chinese seaweed Laminaria

Overview

Van Hulle and colleagues studied arsenic metabolites in human urine, blood, serum, and packed cells after healthy volunteers ingested Chinese supermarket Laminaria. The occurrence-relevant food matrix is the Laminaria sample itself; urine, blood, serum, packed-cell, and simulated-gastric-fluid values are retained as exposure and metabolism context. The source reports total arsenic in the seaweed and identifies DMA, MA, and DMAE as urinary metabolites, but it does not report an inorganic-arsenic concentration for the seaweed.

Key numbers

Food-matrix value:

Urine arsenic after unboiled Laminaria ingestion:

Table 3 reports arsenic concentrations in blood compartments of two volunteers as ng g-1, mean ± sd:

Simulated gastric-fluid findings:

• For boiled Laminaria incubated in simulated gastric fluid, INAA measurements showed total arsenic in each sample remained between 14.3 and 16.3 mg kg-1 As.
• In the same experiment, the amounts of arsenosugars and DMA decreased while a compound with mass 254 Da increased.
• The MRM transitions recorded were 255 -> 195 for the compound with mass 254 Da, 329 -> 97 for arsenosugar OH, 139 -> 109 for DMA, 483 -> 97 for arsenosugar PO4, and 393 -> 97 for arsenosugar SO3.
• The authors state that non-boiled Laminaria showed similar results, but the arsenosugar breakdown was slower and DMA remained stable.

Methods (brief)

The Laminaria sample was bought at a Chinese supermarket in Beijing and stored at room temperature before analysis. Volunteers ingested 20-25 g (dry mass) of algae within 30 min after the seaweed was cleaned with tap water and rinsed with deionized water; some experiments used unboiled Laminaria and one used boiled Laminaria. Total arsenic in the algae was measured by instrumental neutron activation analysis; urine total arsenic used ICP-MS, blood/serum/packed-cell arsenic used HGAFS after acid digestion, and speciation used HPLC-ICP-MS plus HPLC-ES-MS/MS structural confirmation. Simulated gastric fluid followed US Pharmacopeia composition, used pH about 1.2, and incubated seaweed at 37 °C.

Implications

This source is useful as seaweed exposure-context evidence, not as a broad occurrence survey. It anchors the ingested Laminaria at 43.2 ± 0.4 mg kg-1 total arsenic, then documents how arsenosugar-derived species appeared in urine and how blood-compartment arsenic did not show a marked rise through 7 h. Because the paper does not report inorganic arsenic in the seaweed, total arsenic from this source should not be substituted for inorganic arsenic (iAs).

Related evidence

• Seaweed/kelp foods (nori, wakame, kombu, dulse — as food products)
• Seaweed
• Arsenic, Total

Update history

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