Ingestion and excretion of arsenic compounds present in edible brown algae, Hijikia fusiforme, by mice

Overview

Ichikawa and colleagues measured arsenic species in supplied hijiki before and after cooking, then administered cooked or dried hijiki to mice to study excretion and residual tissue arsenic. The occurrence-relevant data are the Table 2 concentrations in cooked and dried hijiki; urine, feces, and mouse-tissue results are exposure/metabolism context only. The source keeps inorganic arsenic distinct from total arsenic.

Key numbers

Table 2 reports concentrations as µg As/g; the table labels the matrices as cooked hijiki and dried hijiki, but the extracted text does not state a wet-weight or dry-weight basis beyond those matrix labels. No unit conversion was performed.

The source text summarizes the same Table 2 result as a large inorganic arsenic (iAs) amount in dried hijiki, with dried-hijiki iAs at 104 ± 3.2 ng As/g, cooked-hijiki total arsenic at 28 ± 2.5 ng As/g, and cooked-hijiki total iAs at 13 ± 1.0 ng As/g. This appears internally inconsistent with the Table 2 unit header (µg As/g); the source page preserves the table unit and flags the text-unit inconsistency rather than normalizing it.

Single-dose mouse excretion context from Table 3 and results text, reported as total arsenic in ng As:

The single-dose results state that 66-92% of arsenic was excreted within 3 days after administration, with 10-30% excreted in urine and 42-73% in feces.

Repeated-dose mouse-tissue context from Table 4, reported as ng As/g (mean + SD, n = 3):

The repeated-dose results state that urinary and fecal excretion for cooked hijiki were 682 ng As/day and 1255 ng As/day, respectively, on the first dosing day, and that total excretion on day 9 was 1836 ng As/day compared with 1938 ng As/day on day 1. The abstract and discussion state that only approximately 5% of the administered arsenic dose was detected as residual arsenic in mice.

Methods (brief)

Dried H. fusiforme was supplied by the Hijiki Cooperative Society Japan. The source prepared cooked hijiki by soaking dried hijiki in pure water for 30 min at room temperature and heating it in pure water for 20 min at 90 °C. Male ICR mice received a single cooked-hijiki dose of 35, 70, or 140 mg (n = 6 per dose), or repeated 70 mg doses of cooked or dried hijiki on days 1, 3, 5, 7, and 9 (n = 3).

For hijiki arsenic, 0.1 g of uniformly cooked hijiki powder was heated in 1 mL nitric acid for 1 h at 80 °C, neutralized with ammonium hydroxide, filtered through a 0.45 µm filter, and measured by ICP-MS. Arsenic speciation used HPLC/ICP-MS. Urine, feces, and tissues were analyzed by ICP-MS or HPLC/ICP-MS after source-described filtration, nitric-acid digestion, neutralization, or freeze-drying steps.

Implications

This source adds a narrow hijiki occurrence record with paired cooked and dried arsenic values and a clear iAs/total arsenic (tAs) distinction. Because most of the article is a mouse metabolism experiment, the urine, feces, and tissue numbers should be used only as exposure-context evidence and not routed as product occurrence. The source also contains an internal unit inconsistency between the Table 2 µg As/g header and one results sentence using ng As/g, so any downstream extraction should preserve the table unit and keep the inconsistency visible.

Related evidence

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